Method for passivating perovskite, perovskite and preparation process of perovskite

Abstract

The invention relates to the technical field of photoelectric materials, and discloses a method for passivating perovskite, the perovskite and a preparation process of the perovskite, and the method comprises the following steps: S1, adding a passivating agent into a perovskite precursor solution to form a passivation precursor solution; s2, coating the passivation precursor solution on the surface of a substrate through a spin-coating process, and dropwise adding an anti-solvent in the spin-coating process to promote crystallization of perovskite crystal grains; s3, carrying out annealing treatment on the perovskite crystal grains to form a preliminarily passivated perovskite thin film; s4, coating the surface of the passivated perovskite thin film with a passivated material layer; and S5, further depositing a protective layer on the surface of the passivation material layer. A multifunctional passivating agent and a two-dimensional passivating material are introduced to the surface of the perovskite crystal, so that the defect state density of the surface and the grain boundary is reduced, and non-radiative recombination is effectively inhibited. According to the method, the service life and mobility of carriers are improved, and the photoelectric property of the thin film is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic materials, and in particular to a method for passivating perovskite, perovskite and a preparation process of perovskite. Background Art

[0002] Perovskite materials have become a research hotspot in the field of optoelectronic devices such as photovoltaic cells, light-emitting diodes (LEDs) and photodetectors due to their excellent optoelectronic properties, such as high light absorption coefficient, high carrier mobility and low non-radiative recombination loss. Typical perovskite materials have an ABX3 crystal structure, where A is a cation (such as methylammonium, formamidine or cesium cation), B is a metal cation (such as lead ion or tin ion), and X is a halide anion (such as iodide ion or bromide ion). With their superior performance, perovskite devices show great potential in terms of photoelectric conversion efficiency and preparation cost. However, the application of perovskite materials still faces the following key technical issues.

[0003] First, there are a large number of defect states on the surface and grain boundaries of perovskite films. These defect states form non-radiative recombination centers, which greatly limit the lifetime and migration efficiency of carriers, resulting in the inability to fully exert the performance of optoelectronic devices. In addition, these defects can also induce ion migration and interfacial charge recombination, thus affecting the long-term stability of the device. Although traditional passivation technology can repair some defects to a certain extent by introducing passivators, it can usually only act on a single type of defect (such as Pb 2+ Empty or I - Vacancies), and its ability to repair complex defects on the surface and grain boundaries is limited.

[0004] Secondly, perovskite materials are highly sensitive to environmental factors (such as moisture, oxygen, and thermal environment) and are prone to degradation under high humidity, strong light, or high temperature conditions. In particular, moisture and oxygen will quickly corrode perovskite films, destroy their crystal structure, and cause rapid degradation of optoelectronic performance. Traditional protection strategies (such as coating the surface with a single hydrophobic material) are usually difficult to solve the problems of chemical defect repair and environmental stability improvement at the same time, and devices still face the risk of performance degradation during long-term use.

[0005] To this end, those skilled in the art provide a method for passivating perovskite, perovskite and a process for preparing perovskite to solve the problems raised in the above background technology. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for passivating perovskite, perovskite and a process for preparing perovskite, which solve the problems of reduced photoelectric performance and short service life caused by surface and interface defects and insufficient environmental stability in existing perovskite materials.

[0007] To achieve the above objectives, the present invention is implemented by the following technical solutions: A method for passivating perovskite, comprising the following steps:

[0008] S1. adding a passivating agent to a perovskite precursor solution to form a passivating precursor solution;

[0009] S2, coating the passivation precursor solution on the substrate surface by spin coating, and adding anti-solvent during the spin coating process to promote the crystallization of perovskite grains;

[0010] S3, annealing the perovskite grains to form a preliminarily passivated perovskite film;

[0011] S4, coating a passivation material layer on the surface of the passivated perovskite film;

[0012] S5. Further depositing a protective layer on the surface of the passivation material layer.

[0013] Preferably, the passivating agent in step S1 is a multifunctional organic molecule passivating agent, and the multifunctional organic molecule passivating agent has at least one functional group that binds to the surface defects of the perovskite, and the functional group is a carboxyl group, an amino group or a halogen group.

[0014] Preferably, the passivation material layer in step S4 is a two-dimensional passivation material, and the two-dimensional passivation material includes but is not limited to Ruddlesden-Popper type perovskite or graphene oxide.

[0015] Preferably, the thickness of the protective layer in step S5 is 5 nm-20 nm.

[0016] A passivated perovskite comprises a perovskite crystal, a passivator layer is distributed outside the perovskite crystal, and a protective layer is coated outside the passivator layer.

[0017] Preferably, the perovskite crystal has an ABX3 structure, wherein:

[0018] A is methylammonium, formamidine or cesium cation;

[0019] B is a lead ion or a tin ion;

[0020] X is an iodide ion or a bromide ion.

[0021] Preferably, the passivator layer comprises a multifunctional organic molecule passivator and a two-dimensional passivation material.

[0022] A preparation process of passivated perovskite, comprising the following steps:

[0023] A. Clean and surface treat the substrate by sequentially cleaning with deionized water, ethanol and isopropanol, and treating with ultraviolet ozone to enhance the hydrophilicity and cleanliness of the substrate surface;

[0024] B. mixing a perovskite precursor solution with a passivating agent to form a passivating precursor solution, and coating the passivating precursor solution on a substrate surface by a spin coating process, adding an anti-solvent during the spin coating process to promote thin film crystallization, and annealing the thin film after the spin coating is completed to form a perovskite thin film;

[0025] C. Coat a two-dimensional passivation material on the surface of the perovskite film, followed by a protective layer.

[0026] Preferably, the time of ultraviolet ozone treatment in step A is 10 min to 30 min; the spin coating speed in step B is 2000 rpm-5000 rpm, and the spin coating time is 20S to 40S; the amount of antisolvent added in step B is 10 μL-50 μL; the annealing temperature in step B is 80°C-120°C, and the annealing time is 10min-30min.

[0027] Preferably, the cationic component of the perovskite precursor solution in step B is a combination of methylammonium, formamidine and cesium ions.

[0028] The present invention provides a method for passivating perovskite, perovskite and a process for preparing perovskite, which have the following beneficial effects:

[0029] 1. The present invention reduces the defect state density on the surface and at the grain boundary by introducing a multifunctional passivator and a two-dimensional passivation material on the surface of the perovskite crystal, effectively suppressing non-radiative recombination. This method improves the lifetime and mobility of carriers and optimizes the photoelectric properties of the film.

[0030] 2. The present invention adopts a dual protection strategy of two-dimensional passivation material and protective layer, which effectively blocks the corrosion of moisture, oxygen and thermal environment on the perovskite film. The two-dimensional passivation material repairs the chemical defects by forming a highly stable interface layer, while the protective layer greatly improves the anti-degradation performance of the perovskite material in a humid and hot environment through the role of a physical barrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a step diagram of the passivation perovskite method of the present invention;

[0032] Figure 2 It is a schematic diagram of the preparation process steps of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] Please refer to the attached Figure 1 , an embodiment of the present invention provides a method for passivating perovskite, comprising the following steps:

[0036] S1. Add a passivating agent to a perovskite precursor solution to form a passivating precursor solution; in step S1, the passivating agent is a multifunctional organic molecule passivating agent, and the multifunctional organic molecule passivating agent has at least one functional group that binds to the surface defects of the perovskite, and the functional group is a carboxyl group, an amino group or a halogen group.

[0037] Specifically, in step S1, the preparation of the perovskite precursor solution can be prepared by mixing a cationic precursor and a metal halide precursor in a molar ratio, wherein the cationic precursor can be methylammonium iodide (MAI), formamidine iodide (FAI) or cesium iodide (CsI), and the metal halide precursor can be lead iodide (PbI2) or tin iodide (SnI2). The precursor is dissolved in an organic solvent, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), to form a uniform precursor solution. In order to improve the crystallization quality and optoelectronic properties of the perovskite film, it is necessary to introduce a multifunctional organic molecular passivator into the precursor solution to achieve effective passivation of the film surface and interface defects.

[0038] The selection of multifunctional organic molecular passivators should be combined with their compatibility with the chemical properties of the perovskite surface. Molecules with carboxyl groups (-COOH), amino groups (-NH2) or halogen groups (such as -F, -Cl) are preferred. These functional groups can react with metal cations (such as Pb 2+ ) or halide vacancies (such as I - The carboxyl and amino groups can form stable chemical bonds with Pb through coordination. 2+ Combined with, fill surface defects, reduce non-radiative recombination centers, and thus improve carrier lifetime; while halogen groups can combine with halide vacancies (such as I - vacancies) to further enhance the surface stability and charge transfer efficiency of the perovskite film. For example, a commonly used passivating agent can be glycine, whose carboxyl and amino groups are respectively 2+ and I - Vacancy binding; another option is fluorine-containing organic ammonium salts, which coordinate with metal cations through the high electronegativity of the fluorine group.

[0039] In actual operation, the passivator can be added to the precursor solution at a certain molar ratio (for example, 1%-5% of the molar concentration of PbI2) and evenly dispersed by stirring (the temperature can be controlled at 50°C to 70°C). During the stirring process, it should be ensured that the passivator and the precursor are fully mixed so that they can simultaneously participate in the growth and passivation of the crystals in the subsequent preparation of the perovskite film. In addition, the multifunctional organic molecular passivator can not only passivate surface defects, but also play an interface modification role at the grain boundary, optimize the morphology and density of the film, reduce porosity and leakage current, and further improve the photoelectric conversion performance of the film.

[0040] In the process of introducing the passivator, special attention should be paid to the uniformity of its concentration and distribution to avoid non-uniform coverage or phase separation caused by excessive passivator. In the film formation process, the multifunctional organic molecular passivator can form a dense molecular passivation layer on the surface of the perovskite crystal through molecular self-assembly. This layer can not only effectively repair surface defects, but also play a certain protective role, preventing the intrusion of moisture and oxygen, thereby enhancing the wet-heat stability of the perovskite material.

[0041] S2, coating the passivation precursor solution on the substrate surface by spin coating, and adding anti-solvent during the spin coating process to promote the crystallization of perovskite grains;

[0042] Specifically, in step S2, the coating of the passivation precursor solution is carried out by a spin coating process, the purpose of which is to evenly coat the precursor solution on the substrate surface and achieve precise control of the film thickness and uniformity by controlling the spin coating parameters. The substrate can be a transparent conductive substrate, such as ITO glass or FTO glass, and should undergo a strict cleaning procedure before use, including ultrasonic cleaning with deionized water, ethanol, isopropanol and ultraviolet ozone treatment to ensure surface cleanliness and hydrophilicity, thereby improving the adhesion and uniformity of the perovskite film.

[0043] During the spin coating process, a two-step spin coating method can be used to achieve uniform film formation. The first step of low-speed spin coating (such as 1000rpm to 2000rpm, 10 seconds to 20 seconds) is used to spread the passivation precursor solution to form an initial covering layer on the substrate surface; the second step of high-speed spin coating (such as 3000rpm to 5000rpm, 20 seconds to 40 seconds) is used to evenly stretch the film, adjust the thickness, and remove excess solvent. The selection of spin coating parameters such as speed and time needs to be optimized in combination with the viscosity of the perovskite precursor solution, solvent volatility, and target film thickness.

[0044] In the high-speed spin coating stage, in order to promote the rapid crystallization of perovskite grains, antisolvents need to be added during the spin coating process. Antisolvents are usually liquids that are not miscible with the components in the perovskite precursor solution but can quickly extract solvents, such as chlorobenzene, toluene or ether. The role of the antisolvent is to accelerate the precipitation and crystallization of inorganic salts and organic cationic components in the precursor by changing the solubility equilibrium of the solution, thereby increasing the grain size and film density. The amount of antisolvent added is generally controlled between 10μL and 50μL, and is adjusted according to the film area and spin coating conditions. When adding the antisolvent, ensure that the operation is uniform and synchronized with the spin coating process to avoid local crystallization or uneven coverage.

[0045] After spin coating, the film usually needs to be immediately thermally annealed to further promote crystal growth. The annealing temperature is controlled at 80°C to 120°C for 10 to 30 minutes (the specific annealing conditions will be detailed in the subsequent steps). During the annealing process, the perovskite grains are further densified through molecular rearrangement and growth, and the surface passivation molecules simultaneously bind to the crystal surface and interface defects to complete the dynamic passivation process.

[0046] S3, annealing the perovskite grains to form a preliminarily passivated perovskite film;

[0047] Specifically, in step S3, annealing is a key process step for perovskite grain growth, and its purpose is to drive the further rearrangement and crystallization of perovskite crystals through thermal energy, optimize the grain morphology, improve the density of the film, and promote the combination of passivation molecules with perovskite surface defects. Through annealing, the grain boundaries and surface defects can be significantly reduced, and the initial passivation process is completed, laying the foundation for subsequent passivation enhancement and protective layer deposition.

[0048] The temperature range of the annealing treatment is usually controlled between 80°C and 120°C, and the specific temperature is selected according to the components in the perovskite precursor solution and the thermal stability of the substrate material. Too low an annealing temperature may lead to insufficient crystal growth, small grain size, and insufficient film density; while too high an annealing temperature may cause perovskite decomposition, especially in systems containing organic components (such as methylammonium or formamidine). Therefore, in mixed perovskite structures (such as FA-Cs or FA-MA-Cs perovskites), 100°C is usually selected as the typical value of the annealing temperature to achieve a balance between crystal growth and material stability.

[0049] The annealing time is generally controlled between 10 minutes and 30 minutes, and the specific time needs to be optimized according to the film thickness and spin coating conditions. A shorter annealing time may lead to insufficient crystal growth, while an excessively long annealing time may cause excessive grain size or loss of passivation molecules at the grain boundary, affecting the passivation effect.

[0050] During the annealing process, the solvent in the perovskite film gradually evaporates, and the unreacted components in the precursor rearrange and react to form perovskite crystals. The input of thermal energy promotes the diffusion and equilibrium distribution of ions in the crystal, reducing lattice defects and chemical inhomogeneities at grain boundaries. At the same time, the multifunctional organic molecular passivator introduced earlier interacts with defects on the perovskite surface and grain boundaries (such as Pb 2+ Vacancy and I - vacancies) to further reduce the defect state density.

[0051] To avoid environmental disturbances during annealing (such as film degradation caused by humidity or oxygen), annealing can be performed under inert gas protection (such as nitrogen or argon) or in a closed environment with low humidity. In addition, the substrate should be heated evenly on a hot plate to avoid thermal stress cracks on the film surface or uneven crystal growth caused by local heating.

[0052] After annealing, the formed perovskite film usually has high density and large grain size, and the interface quality between grains is significantly improved. The combination of passivation molecules and the crystal surface further enhances the chemical stability and photoelectric properties of the perovskite film. This preliminary passivation film can be directly used in subsequent passivation enhancement steps or the deposition of a protective layer to further optimize device performance and environmental tolerance. By optimizing the annealing process, the light absorption capacity, carrier transport efficiency and charge separation performance of the film can be significantly improved, providing a high-quality material basis for high-efficiency photovoltaic or photoelectric devices.

[0053] S4, coating a passivation material layer on the surface of the passivated perovskite film; in step S4, the passivation material layer is a two-dimensional passivation material, and the two-dimensional passivation material includes but is not limited to Ruddlesden-Popper type perovskite or graphene oxide.

[0054] Specifically, in step S4, the coating of the passivation material layer is intended to further repair the residual defects on the surface and interface of the perovskite film, optimize the interfacial chemical properties of the film, and provide a uniform functional layer for the deposition of the subsequent protective layer. Two-dimensional passivation materials have significant advantages in improving the performance of perovskite films due to their unique layered structure, high surface coverage, and excellent interface compatibility with perovskite crystals.

[0055] The two-dimensional passivation material can be a Ruddlesden-Popper type perovskite (such as BA2PbI4, BA is a phenylethylamine cation) or graphene oxide (GO), or other layered materials (such as black phosphorus or MXene). Ruddlesden-Popper type perovskite has good compatibility with three-dimensional perovskite crystals through its organic-inorganic layered structure. Its organic part can form a flexible molecular layer on the surface of the perovskite film, combine with the ionic defects on the surface of the perovskite, and repair the surface Pb 2+ and I - vacancies, while its inorganic part can enhance the stability of the film interface. Graphene oxide can effectively fill the chemical defects on the surface of perovskite due to its rich surface oxygen-containing functional groups (such as hydroxyl, epoxy and carboxyl) and provide a uniform protective layer on the surface of the film.

[0056] The coating of the two-dimensional passivation material can be carried out by a solution processing process, such as spin coating or dip coating. First, the two-dimensional material is dissolved or dispersed in a solvent to form a stable coating solution. For example, Ruddlesden-Popper perovskite can be dissolved in a polar organic solvent (such as N,N-dimethylformamide, DMF); graphene oxide can be dispersed in isopropanol or water and ultrasonically treated to form a uniform dispersion. The solution concentration is generally controlled at 0.01M to 0.1M (for Ruddlesden-Popper perovskite) or 0.1wt% to 1wt% (for graphene oxide) to ensure uniform coverage during the coating process.

[0057] In the specific coating process, the two-dimensional passivation material solution can be dripped or dipped on the surface of the perovskite film, and then evenly covered by spin coating (speed range of 3000rpm to 5000rpm, time of 20 seconds to 40 seconds). In order to enhance the bonding between the two-dimensional material and the perovskite film, after coating, a short annealing (annealing time of 5 minutes to 10 minutes) can be performed at a low temperature (such as 80°C to 100°C) to drive off residual solvents and promote the formation of a dense passivation layer of the two-dimensional material on the perovskite surface.

[0058] The role of two-dimensional passivation materials is not limited to filling surface chemical defects. Their layered structure can also block the intrusion of water and oxygen into perovskites, significantly improving the environmental tolerance and stability of the film. In addition, due to the excellent optical transparency of two-dimensional passivation materials (such as the wide bandgap characteristics of Ruddlesden-Popper perovskites or the high transmittance of graphene oxide), the coated passivation material layer will not significantly affect the light absorption of the film. For photovoltaic devices, the two-dimensional passivation layer can also reduce the work function of the film surface, making charge transfer more efficient, thereby improving the fill factor and conversion efficiency of the device.

[0059] S5. A protective layer is further deposited on the surface of the passivation material layer. The thickness of the protective layer in step S5 is 5 nm to 20 nm.

[0060] Specifically, in step S5, the purpose of depositing the protective layer is to form a physical barrier on the surface of the passivation material layer, thereby further enhancing the perovskite film's ability to resist environmental erosion (such as moisture and heat resistance and oxidation resistance), while improving the mechanical stability of the device. The selection of the protective layer needs to take into account the compatibility of optical transparency, electrical properties, and processing technology to ensure that while providing a protective function, it does not affect the photoelectric performance of the perovskite film.

[0061] The material of the protective layer can be a hydrophobic organic material, an inorganic oxide or a combination thereof. The hydrophobic organic material is usually a long-chain alkyl ammonium salt, polyvinylidene fluoride (PVDF) or other polymer materials with excellent hydrophobic properties; the inorganic oxide can be aluminum oxide, silicon oxide (SiO2) or zinc oxide (ZnO), which can provide long-term protection for the perovskite film due to its high density and excellent chemical stability.

[0062] The deposition methods of the protective layer include spin coating, dip coating, atomic layer deposition (ALD) or solution chemical deposition (SCD), etc., and the selection of the specific process depends on the material properties and application requirements. For hydrophobic organic materials, the solution spin coating method is often used: the material is dissolved in an appropriate solvent (such as isopropyl alcohol or dimethylformamide), and evenly coated on the surface of the passivation material layer by spin coating (spin coating speed is 3000rpm to 5000rpm, time is 20 seconds to 40 seconds), forming a protective layer with a thickness of 5nm to 20nm. For inorganic oxide materials, atomic layer deposition (ALD) technology is preferably used to grow a dense film on the surface of the passivation material layer with atomic-level precision to ensure the uniformity of film thickness and high coverage.

[0063] During the deposition of the protective layer, the thickness needs to be strictly controlled between 5nm and 20nm. If the thickness of the protective layer is less than 5nm, it may not be able to completely cover the surface of the passivation material layer, resulting in a decrease in the protective effect; while a thickness exceeding 20nm may cause optical loss, thereby reducing the light absorption efficiency and charge transfer performance of the perovskite film. Whether it is spin coating or ALD technology, it is necessary to ensure that the protective layer covers the surface of the passivation material layer uniformly to avoid local missing or excessive accumulation.

[0064] After deposition, the protective layer usually works without further treatment, but for certain organic materials (such as polymers containing double bond groups), the mechanical and chemical stability of the protective layer can be enhanced by UV crosslinking or thermal annealing (temperature of 80°C to 100°C, time of 5 minutes to 10 minutes). In addition, the surface roughness of the protective layer should be as low as possible to reduce the light scattering loss inside the device and provide good substrate conditions for the subsequent superposition of functional layers (such as electrode materials).

[0065] Embodiment 2:

[0066] An embodiment of the present invention provides a passivated perovskite, including a perovskite crystal, a passivator layer distributed outside the perovskite crystal, and a protective layer coated outside the passivator layer.

[0067] Perovskite crystals have an ABX3 structure, where:

[0068] A is methylammonium, formamidine or cesium cation;

[0069] B is a lead ion or a tin ion;

[0070] X is an iodide ion or a bromide ion.

[0071] The passivation agent layer includes a multifunctional organic molecular passivation agent and a two-dimensional passivation material.

[0072] Specifically, perovskite crystal is the core material of the present invention, which has a classic ABX3 crystal structure, wherein:

[0073] A-site cation: It can be methylammonium, formamidine or cesium cation. The cation is located in the cube center of the perovskite lattice and determines the size and chemical stability of the crystal.

[0074] B-site metal cation: can be lead ion (Pb 2+ ) or tin ions (Sn 2+ ), metal cations are located at the corners of the lattice and are the main determinants of the optical and electrical properties of the crystal;

[0075] X-position halide anion: can be iodide ion (I - ) or bromide ion (Br - ), the halides are located at the corners of the lattice and are responsible for the electronic structure and band gap regulation of the crystal.

[0076] The present invention introduces a passivator layer outside the perovskite crystal to repair the chemical defects on the surface and interface, reduce non-radiative recombination centers, and improve the stability and photoelectric performance of the film. The passivator layer includes the following two main components:

[0077] Multifunctional organic molecule passivator:

[0078] Multifunctional organic molecular passivators interact with metal cations (such as Pb) on the surface of perovskite crystals through their functional groups (such as carboxyl, amino or halogen groups). 2+ or Sn 2+ ) or halide vacancies (such as I - vacancies) to repair surface defects.

[0079] In a specific implementation, glycine, fluorine-containing organic ammonium salts or organic molecules with long-chain alkyl groups can be selected. These molecules can provide certain hydrophobic protection while being passivating.

[0080] 2D passivation materials:

[0081] The two-dimensional passivation material forms a functional protective layer on the crystal surface through its layered structure and high chemical stability, while further filling surface defects and reducing the interfacial charge load.

[0082] Two-dimensional materials may include Ruddlesden-Popper type perovskites or graphene oxide, which can not only effectively passivate but also enhance the environmental stability of the material.

[0083] A protective layer is coated on the outside of the passivator layer, which serves to provide a further physical barrier for the perovskite, preventing the intrusion of moisture and oxygen from the environment, while improving the mechanical strength and long-term stability of the film.

[0084] Protective layer material:

[0085] The protective layer may be made of hydrophobic organic materials (such as long-chain alkyl ammonium salts, polyvinylidene fluoride) or inorganic oxides (such as aluminum oxide, silicon oxide).

[0086] Inorganic oxide protective layers provide excellent protection through their compactness, while organic materials are known for their flexibility and low cost.

[0087] Thickness of protective layer:

[0088] In order to strike a balance between the protective effect and the optical performance, the thickness of the protective layer is controlled in the range of 5nm to 20nm. A protective layer that is too thin may not completely cover the passivator layer, while a protective layer that is too thick may affect the light absorption efficiency.

[0089] Deposition method:

[0090] For the organic protective layer, a spin coating process can be used for coating;

[0091] For the inorganic oxide protective layer, atomic layer deposition (ALD) technology can be used to ensure high density and uniformity of the protective layer.

[0092] Through the synergistic effect of the passivation layer and the protective layer, the performance of the perovskite crystal is significantly optimized. Specifically:

[0093] The passivator layer effectively repairs the chemical defects on the perovskite surface and reduces the charge recombination of surface and interface states;

[0094] The 2D passivation material provides additional functional protection while optimizing the interface properties between the crystal and the electrode;

[0095] The protective layer provides strong resistance to moisture, heat and oxidation, greatly improving the long-term stability of the perovskite material.

[0096] The above design ensures that the passivated perovskite material can be widely used in optoelectronic devices such as photovoltaic cells, light-emitting diodes and photodetectors.

[0097] Embodiment 3:

[0098] Please refer to the attached Figure 2 The present invention provides a process for preparing a passivated perovskite, comprising the following steps:

[0099] A. Clean and surface treat the substrate by sequentially cleaning with deionized water, ethanol and isopropanol, and then treat with ultraviolet ozone to enhance the hydrophilicity and cleanliness of the substrate surface; the ultraviolet ozone treatment time is 10 minutes to 30 minutes.

[0100] Specifically, the specific operation process is as follows: Substrate selection: The substrate can be a transparent conductive substrate (such as FTO glass or ITO glass) or other commonly used substrates for optoelectronic devices. The substrate surface needs to have good conductivity and light transmittance to meet the performance requirements of optoelectronic devices.

[0101] Cleaning steps: Use ultrasonic cleaning method to clean the substrate with deionized water, ethanol and isopropanol in sequence to remove particles, grease and organic pollutants. The specific cleaning process is as follows:

[0102] Ultrasonic cleaning with deionized water: Immerse the substrate in an ultrasonic bath for 5 to 10 minutes to remove inorganic particles and dissolved contaminants;

[0103] Ethanol ultrasonic cleaning: Replace the cleaning solution with ethanol and clean for 5 to 10 minutes to remove grease and some organic matter;

[0104] Isopropyl alcohol ultrasonic cleaning: Replace the cleaning solution with isopropyl alcohol and clean for 5 to 10 minutes to further remove organic residues on the substrate surface and ensure that the substrate surface dries quickly after cleaning.

[0105] After each cleaning, blow dry the substrate surface with clean nitrogen to avoid water stains or cleaning solution residues.

[0106] UV-ozone treatment: The cleaned substrate is placed in a UV-ozone cleaning machine for UV-ozone treatment for 10 to 30 minutes. UV-ozone treatment uses ozone generated by UV light to react with organic pollutants on the surface, oxidizing the organic residues into carbon dioxide and water, while forming a thin hydrophilic oxide layer on the surface of the substrate.

[0107] Mechanism of action: When ultraviolet light irradiates the surface of the substrate, it can destroy the molecular bonds of residual organic matter;

[0108] The strong oxidizing property of ozone further oxidizes and removes residual pollutants, enhancing the cleanliness of the substrate surface;

[0109] The oxide layer formed on the substrate surface can improve the adhesion of the film and provide an optimized interface for the subsequent film formation process.

[0110] Storage and preparation: The treated substrate should be used immediately in the subsequent film preparation process to avoid environmental contamination or the surface being affected by moisture again. If storage is required, the substrate should be placed in a clean, dry environment or protected with dry nitrogen.

[0111] B. Mix the perovskite precursor solution with the passivating agent to form a passivating precursor solution, and apply the passivating precursor solution to the substrate surface by spin coating. During the spin coating process, add anti-solvent to promote film crystallization. After the spin coating is completed, anneal the film to form a perovskite film. The spin coating speed is 2000rpm-5000rpm, and the spin coating time is 20S to 40S. The amount of anti-solvent added is 10μL-50μL. In step B, the annealing temperature is 80℃-120℃, and the annealing time is 10min-30min.

[0112] The cationic components of the perovskite precursor solution are a combination of methylammonium, formamidine and cesium ions.

[0113] Specifically, through the specific operation of this step, high uniformity and high-quality film formation of the perovskite film can be achieved:

[0114] The perovskite precursor solution is combined with the passivator to ensure that the film is passivated synchronously during the crystal growth process, repairing the crystal surface and interface defects;

[0115] The spin coating process achieves uniform distribution and thickness control of the film through precise speed and time control;

[0116] Antisolvent droplet addition accelerates the crystallization and growth of grains, forming a dense film structure;

[0117] Annealing treatment optimizes the crystal arrangement and chemical properties, improving the optoelectronic properties and long-term stability of the film.

[0118] C. Coat a two-dimensional passivation material on the surface of the perovskite film, followed by a protective layer.

[0119] Specifically, by coating the two-dimensional passivation material and the protective layer, this step achieves dual optimization of the performance and stability of the perovskite film:

[0120] The two-dimensional passivation material effectively fills the chemical defects on the perovskite surface, reduces the number of non-radiative recombination centers, and improves the optoelectronic properties of the film;

[0121] The protective layer significantly improves the perovskite film's resistance to moisture, heat and oxidation through its physical barrier function, ensuring long-term operational reliability.

[0122] The overall film structure has excellent optical transparency, low defect state density and environmental tolerance, and is suitable for high-performance optoelectronic devices.

[0123] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for passivating perovskite, characterized in that: The following steps are involved: S1. adding a passivating agent to a perovskite precursor solution to form a passivating precursor solution; S2, coating the passivation precursor solution on the substrate surface by spin coating, and adding anti-solvent during the spin coating process to promote the crystallization of perovskite grains; S3, annealing the perovskite grains to form a preliminarily passivated perovskite film; S4, coating a passivation material layer on the surface of the passivated perovskite film; S5. Further depositing a protective layer on the surface of the passivation material layer.

2. A method for passivating perovskite according to claim 1, characterized in that: In the step S1, the passivating agent is a multifunctional organic molecule passivating agent, and the multifunctional organic molecule passivating agent has at least one functional group that binds to the surface defects of the perovskite, and the functional group is a carboxyl group, an amino group or a halogen group.

3. A method for passivating perovskite according to claim 1, characterized in that: In the step S4, the passivation material layer is a two-dimensional passivation material, and the two-dimensional passivation material includes but is not limited to Ruddlesden-Popper type perovskite or graphene oxide.

4. A method for passivating perovskite according to claim 1, characterized in that: The thickness of the protective layer in step S5 is 5nm-20nm.

5. A passivated perovskite, a method for passivating perovskite according to any one of claims 1 to 4, characterized in that: The invention comprises a perovskite crystal, a passivator layer is distributed outside the perovskite crystal, and a protective layer is coated outside the passivator layer.

6. A passivated perovskite according to claim 5, characterized in that: The perovskite crystal has an ABX3 structure, wherein: A is methylammonium, formamidine or cesium cation; B is a lead ion or a tin ion; X is an iodide ion or a bromide ion.

7. A passivated perovskite according to claim 5, characterized in that: The passivation agent layer comprises a multifunctional organic molecular passivation agent and a two-dimensional passivation material.

8. A process for preparing a passivated perovskite, according to a passivated perovskite according to any one of claims 5 to 7, characterized in that: The following steps are involved: A. Clean and surface treat the substrate by sequentially cleaning with deionized water, ethanol and isopropanol, and treating with ultraviolet ozone to enhance the hydrophilicity and cleanliness of the substrate surface; B. mixing a perovskite precursor solution with a passivating agent to form a passivating precursor solution, and coating the passivating precursor solution on a substrate surface by a spin coating process, adding an anti-solvent during the spin coating process to promote thin film crystallization, and annealing the thin film after the spin coating is completed to form a perovskite thin film; C. Coat a two-dimensional passivation material on the surface of the perovskite film, followed by a protective layer.

9. A process for preparing a passivated perovskite according to claim 8, characterized in that: The time of ultraviolet ozone treatment in step A is 10 min to 30 min; the spin coating speed in step B is 2000 rpm-5000 rpm, and the spin coating time is 20S to 40S; the amount of anti-solvent added in step B is 10 μL-50 μL; the annealing temperature in step B is 80°C-120°C, and the annealing time is 10min-30min.

10. The process for preparing a passivated perovskite according to claim 8, characterized in that: The cationic component of the perovskite precursor solution in step B is a combination of methylammonium, formamidine and cesium ions.

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