Flexible perovskite solar cell based on oleylamine chlorine passivator and preparation method thereof

Abstract

The application discloses a flexible perovskite solar cell based on an oleylamine chlorine passivation agent and a preparation method thereof, and relates to the technical field of solar cells. The solar cell comprises, from bottom to top, a flexible substrate, an electron transport layer, a perovskite light absorption layer, an oleylamine chlorine interface passivation layer, a hole transport layer and a gold electrode layer. In the preparation, after the perovskite light absorption layer is formed, an oleylamine chlorine solution is coated on the surface of the perovskite light absorption layer by using a low-temperature solution spin coating method, and the passivation layer is obtained through heating and drying. The chloride ions in the oleylamine chlorine molecules directly passivate uncoordinated defects on the surface of the perovskite, inhibit non-radiative recombination and optimize energy level matching. Meanwhile, the long-chain alkyl groups in the molecules construct a hydrophobic barrier layer to block the environmental water and oxygen erosion. Through simple interface engineering modification, the application improves the photoelectric conversion efficiency and environmental stability of the device, and the process is matched with the flexible substrate, which is beneficial to large-scale production.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and in particular to flexible perovskite solar cells based on oleylamine chloride passivating agent and their preparation methods. Background Technology

[0002] Currently, the new energy vehicle industry is developing rapidly. Vehicle-mounted photovoltaic technology, as a means of supplementary power supply and reducing vehicle energy consumption, has attracted attention in the technological field. Flexible perovskite solar cells possess the advantages of high photoelectric conversion efficiency and simple fabrication process. This device also has the physical property of being flexible. This characteristic allows it to adapt to complex installation scenarios such as curved car body surfaces and roofs. Flexible perovskite solar cells have application potential in the field of vehicle power supply.

[0003] Conventional flexible solar cells rely on a multilayer thin-film structure for photoelectric conversion. External light penetrates a flexible transparent substrate and an electron transport layer. The light then strikes the perovskite light-absorbing layer. The perovskite material absorbs photon energy, generating photogenerated electrons and holes. Adjacent electron and hole transport layers extract these two types of charge carriers, respectively. Under the influence of a built-in electric field, the charge carriers migrate directionally to both sides. Finally, the metal electrodes at the bottom and top collect the migrated charges, forming a current in the external circuit.

[0004] After crystallization, perovskite thin films often retain uncoordinated lead ions and halogen vacancies on the surface and at grain boundaries. These intrinsic defects lead to nonradiative recombination of charge carriers. Mechanical vibrations and temperature fluctuations from vehicle operation exacerbate ion migration within the film, resulting in a decline in the device's photoelectric performance. Simultaneously, energy level mismatch exists between the unmodified perovskite layer and the hole transport layer. Interface barriers hinder charge extraction, and energy losses at the interface limit the improvement of the device's photoelectric conversion efficiency. Furthermore, automotive applications face long-term outdoor exposure. External moisture easily penetrates downwards from the interlayer interface, altering the perovskite's crystal structure. The combination of moisture penetration and long-term mechanical vibration causes phase separation and interlayer delamination, shortening the device's lifespan.

[0005] Therefore, the present invention provides a flexible perovskite solar cell based on oleamine chloride passivating agent and its preparation method, so as to overcome the shortcomings of the prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a flexible perovskite solar cell based on oleamine chloride passivating agent and its preparation method, aiming to solve the problems of limited photoelectric conversion efficiency due to interface defects and poor stability due to susceptibility to environmental moisture erosion in existing flexible perovskite solar cells.

[0007] This invention provides the following solution:

[0008] In a first aspect, the present invention provides a flexible perovskite solar cell based on oleylamine chloride passivating agent, employing the following technical solution:

[0009] A flexible perovskite solar cell based on oleamine chloride passivator comprises, from bottom to top, a polyethylene naphthalate-indium tin oxide flexible substrate, an electron transport layer, a perovskite light absorption layer, an oleamine chloride interface passivation layer, a hole transport layer, and a gold electrode layer; the thickness of the electron transport layer is 20–30 nm; the thickness of the oleamine chloride interface passivation layer is 5–20 nm; the thickness of the hole transport layer is 150–220 nm; and the thickness of the gold electrode layer is 65–85 nm.

[0010] By employing the above technical solution, the ammonium ions in the oleamine chloride interface passivation layer can interact with uncoordinated halide ions on the perovskite surface. Chloride ions fill the vacancies of uncoordinated lead ions on the perovskite surface, passivating surface defects through interfacial chemical reactions and suppressing non-radiative recombination. The long-chain alkyl groups of oleamine chloride possess hydrophobic properties, constructing a physical barrier layer between the perovskite light absorption layer and hole transport layer, preventing the intrusion of environmental moisture and inhibiting the outward migration of ions from within the perovskite. Combined with the set thickness parameters of each layer, efficient carrier extraction and transport are achieved, reducing interfacial series resistance. Therefore, the photoelectric conversion efficiency and environmental stability of the battery are improved.

[0011] Preferably, the electron transport layer is a tin dioxide layer.

[0012] By adopting the above technical solution, tin dioxide has high electron mobility and good light transmittance, and is matched with low-temperature preparation process, compatible with flexible polyester substrate, and can realize rapid electron extraction and block hole reverse injection.

[0013] Preferably, the hole transport layer is composed of 2,2',7,7'-tetratetra(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene, tributyl phosphate, and lithium bis(trifluoromethanesulfonyl)imide.

[0014] By adopting the above technical solution, lithium bis(trifluoromethanesulfonyl)imide is used as a dopant to improve the conductivity of the main material system, and tributyl phosphate prevents dopant aggregation and adjusts the film morphology. The three work synergistically to construct an energy level-matched hole transport channel and improve hole collection efficiency.

[0015] Secondly, the present invention provides a method for preparing a flexible perovskite solar cell based on an oleamine chloride passivating agent, employing the following technical solution:

[0016] The method for fabricating flexible perovskite solar cells based on oleylamine chloride passivating agent includes the following steps:

[0017] The surface of a flexible substrate made of polyethylene naphthalate-indium tin oxide (ITO) is pretreated, followed by deposition of a tin dioxide electron transport layer precursor solution and annealing to obtain a tin dioxide electron transport layer. A perovskite lead precursor solution and a perovskite organic cation solution are then spin-coated onto the tin dioxide electron transport layer in stages, followed by sequential annealing to obtain a perovskite light absorption layer. An oleamine chloride solution is spin-coated onto the cooled perovskite light absorption layer, and after heating and drying, an oleamine chloride interface passivation layer is obtained. A hole transport layer solution is spin-coated onto the oleamine chloride interface passivation layer to obtain a hole transport layer. Elemental gold is deposited on the surface of the hole transport layer by vacuum evaporation to obtain a gold electrode layer.

[0018] By adopting the above technical solution, the overall preparation process employs a combination of low-temperature solution spin coating and vacuum evaporation. The specific principle and reaction process are as follows: annealing is performed on the flexible substrate to generate a dense tin dioxide film as an electron transport channel; a two-step spin coating method is used to form a perovskite light-absorbing layer, where the lead precursor reacts stepwise with organic cations to control the crystal growth rate; an oleamine chloride solution is spin-coated onto the perovskite film surface, where oleamine chloride molecules are positioned and distributed at the perovskite grain boundaries and surface during the heating stage, and ammonium groups and chloride ions chemically bond with uncoordinated bonds on the perovskite surface, causing long aliphatic chains to extend outwards to form a hydrophobic interface layer; finally, a hole transport layer and a metal electrode are deposited. This method allows the process flow to match the temperature tolerance limitations of the flexible polyester substrate.

[0019] Preferably, in the step of obtaining the tin dioxide electron transport layer, the pretreatment process is as follows: sequentially cleaning with deionized water, ethanol, and isopropanol for 10-20 minutes each, drying with nitrogen, and then performing ultraviolet ozone treatment for 5-15 minutes; the annealing temperature is 90-150°C, and the time is 30-60 minutes.

[0020] By adopting the above technical solution, multi-stage solvent cleaning combined with ultraviolet ozone treatment removes organic pollutants from the surface of the flexible substrate and increases surface hydroxyl groups, improving the wettability of the precursor solution; specific low-temperature annealing conditions allow tin dioxide colloid to be fully dehydrated and cross-linked to form a film, avoiding thermal deformation of the flexible substrate.

[0021] Preferably, the perovskite lead precursor solution is prepared by dissolving 680-700 mg of lead iodide in a mixed solvent consisting of 900-1000 μL of dimethylformamide, 15-25 μL of dimethyl sulfoxide, and 45-55 μL of cesium iodide-dimethyl sulfoxide at a concentration of 1.2-1.4 mol / L, stirring until fully dissolved, and then filtering. The perovskite organic cation solution is prepared by dissolving 85-95 mg of formamidinium iodide, 4-8 mg of methylamine bromide, and 7-11 mg of methylamine chloride in 0.8-1.2 mL of isopropanol, stirring until fully dissolved, and then filtering.

[0022] By adopting the above technical solution, cesium iodide is introduced to regulate the perovskite lattice tolerance factor, and dimethyl sulfoxide forms an intermediate complex with lead iodide to slow down the crystallization rate, thus providing a precursor basis for subsequent high-quality thin film growth.

[0023] Preferably, the specific process for obtaining the perovskite light-absorbing layer is as follows: after treating the substrate with the deposited tin dioxide electron transport layer with ultraviolet ozone, the perovskite lead precursor solution is spin-coated at a speed of 2500-3500 rpm for 20-40 seconds, and then annealed on a hot stage at 65-75°C for 0.5-2 minutes to form a lead iodide film; then, the perovskite organic cation solution is spin-coated on the lead iodide film at a speed of 2500-3500 rpm for 20-40 seconds, and then annealed on a hot stage at 120-140°C for 0.5-2 minutes, and then transferred to an environment with a relative humidity of 30%-40%, and annealed at 120-140°C for 10-20 minutes.

[0024] By adopting the above technical solution, in the two-step spin coating process, the lead iodide bottom layer and the mixed organic cation top layer undergo intercalation reaction and phase transformation annealing under specific temperature and humidity conditions, reducing pinholes inside the film and obtaining a pure phase dense perovskite film.

[0025] Preferably, in the step of obtaining the oleamine chloride interface passivation layer, the oleamine chloride solution is prepared by dissolving oleamine chloride powder in isopropanol, and the concentration of oleamine chloride in isopropanol is 1-4 mg / mL.

[0026] By adopting the above technical solution, isopropanol is used as an orthogonal solvent to avoid dissolving and damaging the underlying perovskite film, and the set solution concentration range ensures that oleoamine chloride provides sufficient passivation molecules.

[0027] Preferably, in the step of obtaining the oleamine-chlorine interface passivation layer, the spin coating speed of the oleamine-chlorine solution is 3500-4500 rpm, and the spin coating time is 25-35 s; the heating temperature after spin coating is 90-110℃, and the heating time is 3-8 min.

[0028] By adopting the above technical solution, the spin coating parameters are controlled to form a molecular layer of appropriate thickness on the surface of the oleamine chloride, preventing the thickness from being too large to form an insulating barrier that hinders the transport of charge carriers or the thickness from being too small to completely cover the surface defect sites; the annealing process promotes the occurrence of interfacial chemical reactions and solvent evaporation.

[0029] Preferably, the hole transport layer solution is prepared by the following method: 500-540 mg of lithium bis(trifluoromethanesulfonyl)imide is dispersed in 0.8-1.2 mL of acetonitrile to prepare a mixed solution; 72-72.3 mg of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene is added to 0.8-1.2 mL of chlorobenzene, and 15-20 μL of the mixed solution and 25-32 μL of tributyl phosphate are added, and the mixture is stirred until it is completely dispersed and uniform.

[0030] By adopting the above technical solution, the mass and volume ratio of the main and auxiliary materials are limited, so that the additives are uniformly dispersed in the matrix of the main material and reach a specific degree of oxidation doping, thus maintaining the hydrodynamic stability of the solution during the spin coating process.

[0031] The above solution achieves the following beneficial technical effects:

[0032] This invention incorporates an oleamine-chloride interface passivation layer between the perovskite light-absorbing layer and the hole transport layer. The chloride and amino groups in the oleamine-chloride molecule chemically adsorb and bond with uncoordinated lead and iodide ions on the perovskite crystal surface. This specific material layer directly passivates non-radiative recombination defects on the perovskite surface, optimizes energy level matching between adjacent layers, promotes charge extraction and transport at the interface, reduces carrier recombination losses, and improves the open-circuit voltage, short-circuit current density, and overall photoelectric conversion efficiency of the flexible solar cell.

[0033] The oleamine-chlorine interface passivation layer used in this invention has a unique molecular orientation arrangement, with its inherent hydrophobic long-chain alkyl groups forming a physical barrier layer at the interface. This barrier layer, situated above the light-absorbing layer, effectively prevents moisture and oxygen from the external environment from penetrating downwards and eroding the perovskite film, while simultaneously inhibiting the outward migration and degradation of internal ions. This material-level barrier mechanism reduces film degradation caused by environmental factors, improving the environmental stability and actual operating life of the device.

[0034] The method provided by this invention achieves interface modification through a simple solution spin-coating post-treatment process. The use of orthogonal solvents to prepare the oil-amine-chlorine solution avoids secondary dissolution and damage to the underlying crystallized perovskite film during film formation. This interface treatment and the corresponding drying process are both performed at low temperatures, fully compatibility with the thermodynamic limitations of the flexible polyester substrate, and without significantly increasing the complexity of the overall fabrication process. This provides a technical solution for the large-scale production of efficient and stable flexible perovskite photovoltaic devices. Attached Figure Description

[0035] Figure 1 This is a scanning electron microscope image of the flexible perovskite thin film prepared in Example 2 of the present invention;

[0036] Figure 2 A scanning electron microscope image of the flexible perovskite thin film prepared in Comparative Example 1 of the present invention;

[0037] Figure 3 The X-ray photoelectron spectra of the flexible perovskite films prepared in Example 2 and Comparative Example 1 of the present invention are compared; wherein, (a) is the high-resolution spectrum of Pb 4f and (b) is the spectrum of I 3d orbitals.

[0038] Figure 4 The graph shows a comparison of the current density-voltage curves of the flexible perovskite solar cells prepared in Example 2 and Comparative Example 1 of the present invention; wherein, (a) is the test curve of Comparative Example 1 and (b) is the test curve of Example 2.

[0039] Figure 5 The graphs show the long-term operational stability test curves of the flexible perovskite solar cells prepared in Example 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0042] The flexible substrate is made of polyethylene naphthalate-indium tin oxide (PEN-ITO) with a sheet resistance of 15Ω / sq, a light transmittance of ≥80%, and a thickness of 125μm.

[0043] Tin dioxide (SnO2) colloidal dispersion with a solute mass fraction of 15 wt% and pure water as the dispersion medium.

[0044] Lead iodide (PbI2), CAS number 10101-63-0, purity 99.99%, battery grade.

[0045] Formamidinium iodide (FAI), CAS No. 879643-71-7, purity 99.5%, battery grade.

[0046] Methylamine bromide (MABr), CAS number 6876-37-5, purity 99.5%, battery grade.

[0047] Methylamine chloride (MACl), CAS number 593-51-1, purity 99.5%, battery grade.

[0048] Cesium iodide (CsI), CAS number 7789-17-5, purity 99.99%, battery grade.

[0049] Oleamine chloride (OAmCl), CAS number 71010-32-1, purity 99%, specification battery grade.

[0050] 2,2',7,7'-Tetra(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene (Spiro-OMeTAD), CAS No. 207739-72-8, purity 99.5%, battery grade.

[0051] Tributyl phosphate (TBP), CAS number 126-73-8, purity 99%, specification analytical grade.

[0052] Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), CAS No. 90076-65-6, purity 99.5%, battery grade.

[0053] Elemental gold (Au), CAS number 7440-57-5, purity 99.999%, specification is high purity vapor deposition grade.

[0054] The main experimental instruments and their specific models involved in the following examples and comparative examples are as follows: UV ozone cleaner (model UVO-Cleaner-42), spin coater (model KW-4A), high-purity nitrogen glove box (model Super-1220), and high vacuum evaporation coating machine (model Vnano-500).

[0055] Preparation Examples 1-4:

[0056] Preparation Example 1:

[0057] This preparation example provides a method for preparing a tin dioxide electron transport layer precursor solution, including the following steps:

[0058] Preparation of solution 1-A: Measure 1 mL of 15 wt% tin dioxide colloidal dispersion, add 4 mL of deionized water to dilute and stir evenly.

[0059] Preparation of solution 1-B: Measure 1 mL of 15 wt% tin dioxide colloidal dispersion, add 5.5 mL of deionized water to dilute and stir evenly.

[0060] Preparation of solution 1-C: Measure 1 mL of 15 wt% tin dioxide colloidal dispersion, add 7 mL of deionized water to dilute and stir evenly.

[0061] Preparation Example 2:

[0062] This preparation example provides a method for preparing a perovskite lead precursor solution, including the following steps:

[0063] Preparation of solution 2-A: 680 mg of lead iodide was dissolved in a mixed solvent consisting of 900 μL of dimethylformamide, 15 μL of dimethyl sulfoxide and 45 μL of cesium iodide-dimethyl sulfoxide with a concentration of 1.2 mol / L. After stirring for 10 h until fully dissolved, the solution was filtered through a 0.22 μm filter membrane.

[0064] Preparation of solution 2-B: 691.5 mg of lead iodide was dissolved in a mixed solvent consisting of 950 μL of dimethylformamide, 20 μL of dimethyl sulfoxide and 50 μL of cesium iodide-dimethyl sulfoxide with a concentration of 1.3 mol / L. After stirring for 10 h until fully dissolved, the solution was filtered to obtain the solution.

[0065] Preparation of solution 2-C: Dissolve 700 mg lead iodide in a mixed solvent consisting of 1000 μL dimethylformamide, 25 μL dimethyl sulfoxide and 55 μL cesium iodide-dimethyl sulfoxide at a concentration of 1.4 mol / L. Stir for 10 h until fully dissolved and then filter to obtain the solution.

[0066] Preparation Example 3:

[0067] This preparation example provides a method for preparing a perovskite organic cation solution, including the following steps:

[0068] Solution 3-A was prepared by dissolving 85 mg formamidin iodide, 4 mg methyl bromide and 7 mg methyl chloride in 0.8 mL isopropanol, stirring for 10 h until fully dissolved, and then filtering.

[0069] Solution 3-B was prepared by dissolving 90 mg formamidin iodide, 6 mg methyl bromide and 9 mg methyl chloride in 1.0 mL isopropanol, stirring for 10 h until fully dissolved, and then filtering.

[0070] Preparation of solution 3-C: Dissolve 95 mg formamidin iodide, 8 mg methyl bromide and 11 mg methyl chloride in 1.2 mL isopropanol, stir for 10 h until fully dissolved and then filter to obtain the solution.

[0071] Preparation Example 4:

[0072] This preparation example provides a method for preparing a hole transport layer solution, including the following steps:

[0073] Preparation of solution 4-A: Disperse 500 mg of lithium bis(trifluoromethanesulfonyl)imide in 0.8 mL of acetonitrile to prepare a mixed solution; add 72 mg of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene to 0.8 mL of chlorobenzene, and add 15 μL of the mixed solution and 25 μL of tributyl phosphate, and stir until completely dispersed.

[0074] Preparation of solution 4-B: 520 mg of lithium bis(trifluoromethanesulfonyl)imide was dispersed in 1.0 mL of acetonitrile to prepare a mixed solution; 72.1 mg of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene was added to 1.0 mL of chlorobenzene, along with 17.5 μL of the mixed solution and 28.8 μL of tributyl phosphate, and the mixture was stirred until completely dispersed.

[0075] Preparation of solution 4-C: 540 mg of lithium bis(trifluoromethanesulfonyl)imide was dispersed in 1.2 mL of acetonitrile to prepare a mixed solution; 72.3 mg of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene was added to 1.2 mL of chlorobenzene, along with 20 μL of the mixed solution and 32 μL of tributyl phosphate, and stirred until completely dispersed.

[0076] Examples 1-3:

[0077] Example 1:

[0078] This embodiment provides a flexible perovskite solar cell based on oleamine chloride passivating agent and its preparation method, using a 1 mg / mL oleamine chloride interface passivation layer, including the following steps:

[0079] Pretreatment of the substrate: Cut the polyethylene naphthalate-indium tin oxide flexible substrate into 25mm×25mm pieces, clean it sequentially with deionized water, ethanol and isopropanol for 10min each, dry it with nitrogen and then treat it with ultraviolet ozone for 5min.

[0080] Preparation of tin dioxide electron transport layer: Using solution 1-A from Preparation Example 1, it was deposited on the substrate surface to form a tin dioxide electron transport layer precursor solution, and annealed at 90°C for 30 min to obtain a tin dioxide electron transport layer with a thickness of 20 nm.

[0081] Preparation of perovskite light-absorbing layer: After treating the substrate with the deposited tin dioxide electron transport layer with ultraviolet ozone, solution 2-A from Preparation Example 2 was first spin-coated at 2500 rpm for 20 s, and then annealed on a hot stage at 65°C for 0.5 min to form a lead iodide film; then solution 3-A from Preparation Example 3 was spin-coated on the lead iodide film at 2500 rpm for 20 s, and annealed on a hot stage at 120°C for 0.5 min, and then transferred to an environment with a relative humidity of 30% and annealed at 120°C for 10 min to obtain the perovskite light-absorbing layer.

[0082] Preparation of oleamine chloride interface passivation layer: oleamine chloride powder was dissolved in isopropanol to prepare an oleamine chloride solution with a concentration of 1 mg / mL; the oleamine chloride solution was spin-coated onto the cooled perovskite light absorption layer at a spin speed of 3500 rpm for 25 s; after spin-coating, the layer was heated and dried at 90℃ for 3 min to obtain an oleamine chloride interface passivation layer with a thickness of 5 nm. This layer is used to construct chemical bonds between the perovskite light absorption layer and the hole transport layer to form a hydrophobic barrier layer, thereby passivating interface defects and improving the environmental stability of the device.

[0083] Preparation of hole transport layer: Solution 4-A from Preparation Example 4 was spin-coated onto the surface of the passivation layer at the oil-amine-chlorine interface to obtain a hole transport layer with a thickness of 150 nm.

[0084] Preparation of metal electrode layer: Elemental gold is deposited on the surface of the hole transport layer by vacuum evaporation to obtain a gold electrode layer with a thickness of 65 nm, thus obtaining a flexible perovskite solar cell based on oleamine chloride passivator.

[0085] Example 2:

[0086] This embodiment provides a flexible perovskite solar cell based on oleamine chloride passivating agent and its preparation method, using a 2.5 mg / mL oleamine chloride interface passivation layer, including the following steps:

[0087] Pretreatment of the substrate: Cut the polyethylene naphthalate-indium tin oxide flexible substrate into 25mm×25mm pieces, clean it sequentially with deionized water, ethanol and isopropanol for 15min each, dry it with nitrogen and then treat it with ultraviolet ozone for 10min.

[0088] Preparation of tin dioxide electron transport layer: Solution 1-B from Preparation Example 1 was used to deposit it on the substrate surface to form a tin dioxide electron transport layer precursor solution, and then annealed at 130°C for 40 min to obtain a tin dioxide electron transport layer with a thickness of 25 nm.

[0089] Preparation of perovskite light-absorbing layer: After treating the substrate with the deposited tin dioxide electron transport layer with ultraviolet ozone, the solution 2-B from Preparation Example 2 was first spin-coated at 3000 rpm for 30 s, and then annealed on a hot stage at 70°C for 1 min to form a lead iodide film; then, the solution 3-B from Preparation Example 3 was spin-coated on the lead iodide film at 3000 rpm for 30 s, and then annealed on a hot stage at 130°C for 1 min. Subsequently, it was transferred to an environment with a relative humidity of 35% and annealed at 130°C for 15 min to obtain the perovskite light-absorbing layer.

[0090] Preparation of the oleamine chloride interface passivation layer: oleamine chloride powder was dissolved in isopropanol to prepare an oleamine chloride solution with a concentration of 2.5 mg / mL; the oleamine chloride solution was spin-coated onto the cooled perovskite light absorption layer at a spin speed of 4000 rpm for 30 s; after spin-coating, the layer was heated and dried at 100℃ for 5 min to obtain an oleamine chloride interface passivation layer with a thickness of 12 nm. This layer is used to construct chemical bonds between the perovskite light absorption layer and the hole transport layer to form a hydrophobic barrier layer, thereby passivating interface defects and improving the environmental stability of the device.

[0091] Preparation of hole transport layer: Solution 4-B from Preparation Example 4 was spin-coated onto the surface of the passivation layer at the oil-amine-chlorine interface to obtain a hole transport layer with a thickness of 185 nm.

[0092] Preparation of metal electrode layer: Elemental gold is deposited on the surface of the hole transport layer by vacuum evaporation to obtain a gold electrode layer with a thickness of 75 nm, thus obtaining a flexible perovskite solar cell based on oleamine chloride passivator.

[0093] Example 3:

[0094] This embodiment provides a flexible perovskite solar cell based on oleamine chloride passivating agent and its preparation method, using a 4 mg / mL oleamine chloride interface passivation layer, including the following steps:

[0095] Pretreatment of the substrate: Cut the polyethylene naphthalate-indium tin oxide flexible substrate into 25mm×25mm pieces, clean it sequentially with deionized water, ethanol and isopropanol for 20min each, dry it with nitrogen and then treat it with ultraviolet ozone for 15min.

[0096] Preparation of tin dioxide electron transport layer: Solution 1-C from Preparation Example 1 was used to deposit it on the substrate surface to form a tin dioxide electron transport layer precursor solution, and then annealed at 150°C for 60 min to obtain a tin dioxide electron transport layer with a thickness of 30 nm.

[0097] Preparation of perovskite light-absorbing layer: After treating the substrate with the deposited tin dioxide electron transport layer with ultraviolet ozone, the solution 2-C from Preparation Example 2 was first spin-coated at 3500 rpm for 40 s, and then annealed on a hot stage at 75°C for 2 min to form a lead iodide film; then the solution 3-C from Preparation Example 3 was spin-coated on the lead iodide film at 3500 rpm for 40 s, and annealed on a hot stage at 140°C for 2 min, and then transferred to an environment with a relative humidity of 40% and annealed at 140°C for 20 min to obtain the perovskite light-absorbing layer.

[0098] Preparation of the oleamine chloride interface passivation layer: oleamine chloride powder was dissolved in isopropanol to prepare an oleamine chloride solution with a concentration of 4 mg / mL; the oleamine chloride solution was spin-coated onto the cooled perovskite light absorption layer at a spin speed of 4500 rpm for 35 s; after spin-coating, the layer was heated and dried at 110℃ for 8 min to obtain an oleamine chloride interface passivation layer with a thickness of 20 nm. This layer is used to construct chemical bonds between the perovskite light absorption layer and the hole transport layer to form a hydrophobic barrier layer, thereby passivating interface defects and improving the environmental stability of the device.

[0099] Preparation of hole transport layer: Solution 4-C from Preparation Example 4 was spin-coated onto the surface of the passivation layer at the oil-amine-chlorine interface to obtain a hole transport layer with a thickness of 220 nm.

[0100] Preparation of metal electrode layer: Elemental gold is deposited on the surface of the hole transport layer by vacuum evaporation to obtain a gold electrode layer with a thickness of 85 nm, thus obtaining a flexible perovskite solar cell based on oleamine chloride passivator.

[0101] Comparative Example 1:

[0102] Compared with Example 2, the difference is that the preparation step of the oil-amine-chlorine interface passivation layer is completely omitted. After the perovskite light absorption layer is prepared and cooled, the Spiro-OMeTAD hole transport layer solution is directly spin-coated on the surface of the perovskite light absorption layer to prepare the hole transport layer. The remaining steps, parameters and processes are exactly the same as in Example 2.

[0103] Test Examples 1-4:

[0104] Test Example 1: Surface Morphology and Grain Boundary Analysis of Perovskite Thin Films

[0105] Test steps:

[0106] The flexible perovskite film sample containing the oleamine-chlorine interface passivation layer prepared in Example 2 and the standard sample without the passivation layer prepared in Comparative Example 1 were cut to obtain a size suitable for scanning electron microscopy testing.

[0107] The sample is fixed to the sample stage using conductive adhesive and then sputtered with gold to enhance its conductivity.

[0108] The sample was placed in the vacuum chamber of a scanning electron microscope (SEM), and the surface microstructure images of the perovskite film were observed and acquired by adjusting the accelerating voltage and magnification.

[0109] By comparing the SEM images of Example 2 and Comparative Example 1, the distribution of oleamine chloride at perovskite grain boundaries and surfaces and its influence on film continuity were analyzed.

[0110] Test data: such as Figure 1 and Figure 2 As shown.

[0111] in conclusion:

[0112] according to Figure 1 and Figure 2 Comparison of scanning electron microscopy (SEM) results shows that the perovskite film of Comparative Example 1, which was not treated with oleamine chloride, exhibits more obvious grain boundaries and a certain degree of roughness on the film surface. In contrast, the surface morphology of the sample of Example 2, after passivation treatment with 2.5 mg / mL oleamine chloride, changed significantly. SEM images show that oleamine chloride molecules effectively adhered to and covered the perovskite grain boundaries and grain surfaces, making the film more compact overall.

[0113] From a mechanistic perspective, the amino group (−NH2) in the oleamine chloride molecule reacts with the chloride ion (Cl... - It can interact with uncoordinated Pb on the perovskite surface and at grain boundaries. 2+ and I - Strong chemical interactions occur at defect sites such as vacancies, forming a stable passivation layer. This adhesion behavior significantly passivates physical and chemical defects on the perovskite film surface caused by lattice discontinuities or ion vacancies, reducing pinholes and microcracks at the interface. Combined with experimental data analysis, this improved microstructure significantly reduces the interfacial contact resistance between the perovskite and hole transport layers, effectively suppressing nonradiative recombination of charge carriers at the interface, thus providing a solid structural foundation for improving hole extraction and transport efficiency. Therefore, the introduction of oleylamine chloride additives not only optimizes the microstructure of the film but also lays the physical foundation for improving the optoelectronic performance of subsequent devices.

[0114] Test Example 2: Analysis of Interfacial Multiple Chemical Bonding Networks and Element Binding Energy

[0115] Test steps:

[0116] The flexible perovskite film sample containing the oleamine chloride interface passivation layer prepared in Example 2 and the control sample without the passivation layer prepared in Comparative Example 1 were cut into sizes of 10 mm × 10 mm.

[0117] The sample to be tested is fixed on the test platform and moved into the ultra-high vacuum analysis chamber of the X-ray photoelectron spectrometer, so that the working pressure reaches 10. -7 Below Pa.

[0118] A monochromatic aluminum target (Al Kα) was used as the X-ray source to perform narrow-scan tests on the Pb 4f orbital and I 3d orbital on the sample surface.

[0119] The obtained energy spectrum data were charged and corrected based on the 1s orbital binding energy of contaminated carbon (284.8 eV), and peak fitting and energy level position recording were performed using data processing software.

[0120] Test data: such as Figure 3 As shown.

[0121] in conclusion:

[0122] according to Figure 3 As can be seen in the figure, Binding Energy represents the binding energy in eV; Intensity represents the photoelectron signal intensity in au; Control represents the Comparative Example 1 sample without a passivation layer; and OAmCl represents the Example 2 sample with a 2.5 mg / mL oleoamine chloride interface passivation layer.

[0123] according to Figure 3 (a) The high-resolution Pb 4f spectrum shows that in the unmodified Comparative Example 1 sample, the Pb 4f orbital exhibits a characteristic double peak, with corresponding binding energies of 138.22 eV (Pb 4f). 7 / 2 (orbital) and 143.12 eV (Pb 4f) 5 / 2 (Orbit). After modification with oleylamine chloride, the Pb 4f of the sample in Example 2 7 / 2 and Pb 4f 5 / 2 The peak positions shifted positively by 0.26 eV (towards 138.48 eV) and 0.2 eV (towards 143.32 eV), respectively. The increase in binding energy indicates that Cl in the oleamine chloride molecule... - Ions and uncoordinated Pb on the perovskite surface 2+ The ions chemically bonded, forming a stable Pb-Cl bond. Due to the high electronegativity of the Cl atom, the outer electron density of the bonded Pb atom decreases, leading to a stronger binding force on the inner electrons due to the nuclear charge, thus causing the binding energy to shift towards higher energies. This microscopically confirms that oleylamine chloride can effectively passivate lead-related defects on the surface of perovskite thin films.

[0124] according to Figure 3 (b) Energy spectrum analysis of the I 3d orbital shows that the I 3d orbital of the Comparative Example 1 sample is at 629.38 eV (I 3d 3 / 2(orbit) and 618.96eV (I 3d) 5 / 2 The sample exhibits a characteristic double peak at the Iorbital. After the introduction of oleylamine chloride modification, these two main peaks in the Example 2 sample shifted positively to 629.58 eV and 619.14 eV, respectively. This positive shift in binding energy is attributed to the interaction between the positively charged amino (-NH2) groups in the oleylamine chloride molecule and the Iorbital on the perovskite surface. - Hydrogen bonds (NH...I) are formed between the ions. The formation of hydrogen bonds reduces the electron density around the I ion, which in turn increases the binding energy of the inner-shell electrons.

[0125] In summary, the simultaneous positive shift of the characteristic peak binding energies of Pb and I elements demonstrates, at the atomic scale, that oleamide chloride binds to perovskite surfaces via Cl. - The -NH2 groups construct a multi-active-site chemical bonding network. This strong interfacial interaction can not only effectively passivate anionic and cation defects on the perovskite surface and reduce the defect state density through a two-site bonding mechanism, but also reduce the carrier transport barrier and suppress interfacial nonradiative recombination by reconstructing the interfacial electronic structure, thereby improving the photoelectric conversion efficiency of flexible perovskite solar cells.

[0126] Test Example 3: Evaluation of Device Photoelectric Conversion Performance and I-V Characteristics

[0127] Test steps:

[0128] The flexible perovskite solar cell samples of Example 2 and Comparative Example 1 were fixed on the fixture of the test platform to ensure that the gold electrode layer of the device maintained good electrical contact with the test probe.

[0129] Turn on the solar simulator and preheat it. Use a standard silicon reference cell to calibrate the output intensity of the light source. Set the test light source conditions to the AM 1.5G standard solar spectrum and the radiation intensity to 100 mW / cm². 2 .

[0130] At room temperature, a digital source meter is used to scan the current-voltage characteristics of a device exposed to light, and the corresponding data of current density and voltage are recorded.

[0131] During the testing process, the same device was tested using both forward and reverse scanning modes to extract photovoltaic parameters and evaluate the device's current-voltage hysteresis.

[0132] Test data: such as Figure 4 As shown in Table 1.

[0133] Table 1. Photovoltaic performance parameters of flexible perovskite solar cells in Comparative Example 1 and Example 2

[0134] sample Scan direction Voc(V) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) PCE (%) Comparative Example 1 positive 1.12 21.14 72.73 17.22 Comparative Example 1 Reverse 1.12 21.15 71.97 17.05 Example 2 positive 1.14 22.43 80.40 20.56 Example 2 Reverse 1.14 22.40 77.42 19.77

[0135] in conclusion:

[0136] according to Figure 4 As can be seen, in the figure, the horizontal axis Voc represents the open-circuit voltage, and the vertical axis Jsc represents the short-circuit current density; in the legend, forward represents forward scanning and reverse represents reverse scanning. Figure 4 (a) shows the current density-voltage curve of the Comparative Example 1 sample without a passivation layer. Figure 4 (b) shows the current density-voltage curves of the sample from Example 2 treated with oleamine chloride as an interface passivation layer.

[0137] According to the data in Table 1, all photoelectric conversion performance parameters of Example 2 are superior to those of Comparative Example 1. The device in Comparative Example 1 has a photoelectric conversion efficiency (PCE) of 17.22% under forward scanning, an open-circuit voltage (Voc) of 1.12V, and a short-circuit current density (Jsc) of 21.14mA / cm². 2 The fill factor (FF) was 72.73%. After the introduction of oleamine chloride modification, the PCE of the device in Example 2 increased to 20.56% under forward scan, Voc increased to 1.14V, and Jsc increased to 22.43 mA / cm². 2 The FF (Fast Forward) improved to 80.40%. The reverse scan data also showed a corresponding performance improvement.

[0138] The improvement in various parameters mechanistically demonstrates the role of the oleamine chloride passivation layer in improving the overall device performance. The increase in Voc is attributed to the chemisorption and multiple bonding of oleamine chloride molecules on the perovskite surface, and the presence of Cl in its structure. - The amino group (-NH2) reacts with uncoordinated Pb. 2+ and I - This process passivates both cation and anion defects on the perovskite surface. The interface modification reduces the defect state density, effectively suppressing defect-induced interfacial nonradiative recombination, thereby reducing voltage drop in the open-circuit state.

[0139] Meanwhile, the improvements in Jsc and FF reflect the enhancement of the overall film quality and interfacial charge transport dynamics. The introduction of the oleamine chloride layer optimizes the energy level arrangement between the perovskite layer and the hole transport layer, reducing the energy barrier for carrier transport across the interface. This reconstructed interfacial electronic structure facilitates the efficient separation and extraction of photogenerated holes, reduces charge accumulation at the interface, and thus improves the current density and fill factor. (Comparison) Figure 4 (a) and Figure 4(b) The overlap between the forward and reverse scan curves shows that, while Example 2 significantly improved efficiency, the current density-voltage curve did not exhibit a significant hysteresis effect. This indicates that the introduction of oleamine chloride hindered ion migration in the interface region, thus consolidating the stability of the perovskite lattice structure. The comprehensive test results demonstrate that oleamine chloride effectively improved the photoelectric conversion efficiency of flexible perovskite solar cells through a synergistic mechanism of interface defect passivation and energy level structure optimization.

[0140] Test Example 4: Long-term operational stability test of unpackaged devices

[0141] Test steps:

[0142] The unencapsulated flexible perovskite solar cells prepared in Example 2 and Comparative Example 1 were placed in an air environment with room temperature and relative humidity of 40% and aged under dark conditions.

[0143] According to the set time nodes, the device was placed under an AM 1.5 G standard simulated solar light source, and its photoelectric conversion efficiency at the corresponding time was tested and recorded.

[0144] The test was continuously tracked for 1000 hours. The photoelectric conversion efficiency data collected at each time point was divided by the initial efficiency of the device, normalized, and a long-term working stability curve was plotted.

[0145] Test data: such as Figure 5 As shown.

[0146] in conclusion:

[0147] according to Figure 5The stability test results of the flexible perovskite solar cells show that the normalized power conversion efficiency (PCE) of the two sets of devices exhibits different degrees of degradation over time. After 1000 hours of aging in an air environment, the PCE of the Comparative Example 1 device without an interface passivation layer drops sharply, eventually remaining at only 50% of its initial value. In contrast, the device of Example 2, which incorporates oleamine chloride as an interface passivation layer, shows a smoother efficiency degradation curve, maintaining 85% of its initial efficiency after 1000 hours. The mechanism behind this difference in durability lies in the presence of hydrophobic long-chain alkyl groups in the oleamine chloride molecule. After spin-coating and heating to form a film, these groups self-assemble on the surface of the perovskite film to form a dense hydrophobic barrier layer. This hydrophobic network effectively resists the penetration and erosion of water vapor and oxygen into the internal perovskite lattice in the test environment, reducing the risk of irreversible phase transition degradation induced by environmental moisture. Meanwhile, the oleamine-chlorine interface layer restricts ion migration behavior on the surface and at grain boundaries of the perovskite material, reducing interface delamination and contact deterioration during long-term storage. The combination of physical moisture barrier and chemical defect passivation maintains the phase stability of the perovskite film itself and the structural stability of the interface with the hole transport layer, thereby reducing the environmental degradation rate of the device's photoelectric performance and extending the device's operating life.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Flexible perovskite solar cell based on an oil amine chloro-passivator, characterized in that, From bottom to top, it includes a flexible substrate of polyethylene naphthalate-indium tin oxide, an electron transport layer, a perovskite light absorption layer, an oleamine-chlorine interface passivation layer, a hole transport layer, and a gold electrode layer. The thickness of the electron transport layer is 20–30 nm; The thickness of the passivation layer at the oleamine-chlorine interface is 5–20 nm. The thickness of the hole transport layer is 150–220 nm; The thickness of the gold electrode layer is 65–85 nm.

2. The flexible perovskite solar cell based on an oil amine chlorinated agent according to claim 1, characterized in that, The electron transport layer is a tin dioxide layer.

3. The flexible perovskite solar cell based on oleamine chloride passivating agent according to claim 1 or 2, characterized in that, The hole transport layer is composed of 2,2',7,7'-tetratetra(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene, tributyl phosphate, and lithium bis(trifluoromethanesulfonyl)imide.

4. A method for fabricating flexible perovskite solar cells based on oleylamine chloride passivating agent, characterized in that, The method for preparing a flexible perovskite solar cell based on oleamine chloride passivator according to any one of claims 1-3 comprises the following steps: The surface of a flexible substrate made of polyethylene naphthalate-indium tin oxide was pretreated, followed by deposition of a tin dioxide electron transport layer precursor solution and annealing to obtain a tin dioxide electron transport layer. A perovskite lead precursor solution and a perovskite organic cation solution were spin-coated onto the tin dioxide electron transport layer in steps and then annealed sequentially to obtain a perovskite light absorption layer. An oil-amine-chloride solution was spin-coated onto the surface of the cooled perovskite light-absorbing layer, and then heated and dried to obtain an oil-amine-chloride interface passivation layer. A hole transport layer solution is spin-coated onto the surface of the passivation layer at the oil-amine-chlorine interface to obtain a hole transport layer; Elemental gold is deposited on the surface of the hole transport layer by vacuum evaporation to obtain a gold electrode layer, thus obtaining the flexible perovskite solar cell based on oleamine chloride passivator.

5. The method for preparing a flexible perovskite solar cell based on an oleamine chloride passivating agent according to claim 4, characterized in that, In the step of obtaining the tin dioxide electron transport layer, the pretreatment process is as follows: Clean with deionized water, ethanol and isopropanol for 10-20 minutes each, dry with nitrogen and then treat with ultraviolet ozone for 5-15 minutes. The annealing temperature is 90–150°C, and the time is 30–60 min.

6. The method for preparing a flexible perovskite solar cell based on oleamine chloride passivating agent according to claim 4, characterized in that, The preparation process of the perovskite lead precursor solution is as follows: 680–700 mg of lead iodide was dissolved in a mixed solvent consisting of 900–1000 μL of dimethylformamide, 15–25 μL of dimethyl sulfoxide, and 45–55 μL of cesium iodide-dimethyl sulfoxide at a concentration of 1.2–1.4 mol / L. The solution was stirred until fully dissolved and then filtered to obtain the product. The preparation process of the perovskite organic cation solution is as follows: The solution is prepared by dissolving 85–95 mg of formamidin iodide, 4–8 mg of methylamine bromide, and 7–11 mg of methylamine chloride in 0.8–1.2 mL of isopropanol, stirring until fully dissolved, and then filtering.

7. The method for preparing a flexible perovskite solar cell based on oleamine chloride passivating agent according to claim 4, characterized in that, The specific process for obtaining the perovskite light-absorbing layer is as follows: After the substrate with the deposited tin dioxide electron transport layer is subjected to ultraviolet ozone treatment, the perovskite lead precursor solution is first spin-coated at a speed of 2500-3500 rpm for 20-40 s, and then annealed on a hot stage at 65-75°C for 0.5-2 min to form a lead iodide film. The perovskite organic cation solution is then spin-coated onto the lead iodide film at a speed of 2500–3500 rpm for 20–40 s, and annealed on a hot plate at 120–140 °C for 0.5–2 min. Subsequently, it is transferred to an environment with a relative humidity of 30%–40% and annealed at 120–140 °C for 10–20 min.

8. The method for preparing a flexible perovskite solar cell based on oleamine chloride passivating agent according to claim 4, characterized in that, In the step of obtaining the oleamine chloride interface passivation layer, the oleamine chloride solution is prepared by dissolving oleamine chloride powder in isopropanol, and the concentration of oleamine chloride in isopropanol is 1-4 mg / mL.

9. The method for preparing a flexible perovskite solar cell based on oleamine chloride passivating agent according to claim 8, characterized in that, In the step of obtaining the oleamine-chlorine interface passivation layer, the spin coating speed of the oleamine-chlorine solution is 3500-4500 rpm, and the spin coating time is 25-35 s; The heating temperature after spin coating is 90-110℃, and the heating time is 3-8 minutes.

10. The method for preparing a flexible perovskite solar cell based on an oleamine chloride passivating agent according to claim 4, characterized in that, The hole transport layer solution is prepared by the following method: Prepare a mixed solution by dispersing 500–540 mg of lithium bis(trifluoromethanesulfonyl)imide in 0.8–1.2 mL of acetonitrile; Add 72–72.3 mg of 2,2',7,7'-tetratetra(N,N-di-p-methoxyphenylamine)-9,9'-spirodifluorene to 0.8–1.2 mL of chlorobenzene, and add 15–20 μL of the mixture and 25–32 μL of tributyl phosphate. Stir until completely dispersed.

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