Functional motif sequence perovskite thin film, preparation method thereof and solar cell device

Abstract

This invention discloses a functional modular ordered perovskite thin film, its preparation method, and a solar cell device. The invention constructs a functional modular ordered perovskite thin film by orderly alternating stacking of two-dimensional and three-dimensional perovskite units. Two-dimensional perovskite unit layers are inserted between two three-dimensional perovskite unit layers. Through the ordered functional units, the two-dimensional perovskite units can confine halide ions within the limited space of the three-dimensional perovskite layers. With the increase in the number of two-dimensional perovskite barrier unit layers, the cyclic migration of halide ions inside the three-dimensional perovskite layer under day-night alternation gradually decreases, thereby enhancing the operational stability of the perovskite solar cell and alleviating device fatigue behavior. Through the orderly stacking of two-dimensional / three-dimensional perovskites and the optimization and matching of the unit structure, it is expected to fundamentally solve many stability problems caused by ion migration.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic new materials technology, and in particular to a functional modular perovskite thin film, its preparation method, and a solar cell device. Background Technology

[0002] With societal development, the demand for energy is increasing, making the development of clean and renewable energy technologies a key approach to solving future energy crises. Solar cells, as a renewable energy technology, have long been highly valued by countries worldwide. However, crystalline silicon-based solar cells have limited their large-scale application due to complex processes, high costs, unclean production processes, high energy consumption, and bulky products. With the emergence of organic-inorganic hybrid perovskite, a new material, photovoltaic technology has gained new vitality. Since its introduction in 2009, its photoelectric conversion efficiency has increased from 3.8% to 25.7%, comparable to monocrystalline silicon cells and surpassing photovoltaic cell technologies such as cadmium telluride and copper indium gallium selenide. However, the current stability of perovskite solar cells is insufficient to support their industrialization.

[0003] The main factors affecting the stability of perovskite solar cells include water and oxygen permeation from the environment, and ion migration and escape within the perovskite. The first two factors can be addressed through effective encapsulation. However, the latter, the random movement driven by external forces such as heat, light, and bias voltage, is an internal factor contributing to the instability of lead halide perovskite materials and cannot be resolved through external encapsulation. Two-dimensional perovskite materials, due to their internal organic long-chain structure, can significantly improve their hydrophobicity and heat resistance. Furthermore, the migration rate of halide ions within two-dimensional perovskites is much lower than that of three-dimensional perovskites. Therefore, two-dimensional perovskites are also an effective way to address perovskite stability. However, the two-dimensional structure also results in stronger dielectric confinement, higher exciton binding energy, a wider band gap, and limited carrier mobility, leading to a photoelectric conversion efficiency far lower than that of three-dimensional perovskite-based solar cell devices. To seek a balance between cell device efficiency and stability, a method of introducing a two-dimensional perovskite layer onto the surface of a three-dimensional perovskite to improve the stability of the perovskite photoactive layer has been proposed and extensively studied. The results show that in this structure, the two-dimensional perovskite can trap halide ions from the three-dimensional perovskite on its surface, preventing them from escaping the photoactive layer and entering other active layers. Therefore, the stability of perovskite solar cells based on this three-dimensional / two-dimensional layered structure is significantly improved under continuous illumination or dark storage conditions.

[0004] However, this three-dimensional / two-dimensional structure can only contain halide ions on the surface of the three-dimensional perovskite layer, and cannot eliminate the migration of halide ions inside the three-dimensional perovskite. Studies have shown that in perovskite solar cells, the accumulation of charge or charged ions at the interface between the perovskite photoactive layer and the charge transport layer exacerbates the fatigue degradation of perovskite solar cells. Fatigue is a unique phenomenon in perovskite solar cells, distinguishing them from other solar cell technologies. During the day-night cycle, the initial efficiency is very low at the start of each illumination period, gradually increasing to the initial efficiency with increasing illumination duration, but the rate of increase decreases with the number of cycles. Research results indicate that during the day-night cycle, halide ions inside the perovskite migrate towards the positive electrode under illumination driven by the built-in electric field, and migrate to the negative electrode under darkness. After prolonged day-night cycles, the repeated migration of halide ions cannot return to their original positions due to the obstruction of grain boundaries and various defects, resulting in a large number of halide vacancies. This is the root cause of the fatigue phenomenon. Fatigue degradation significantly reduces the output power of perovskite solar cells. Currently, there is little reporting on this issue, and no effective solutions exist to address fatigue problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a functional modular perovskite thin film, its preparation method and solar cell device, thereby solving the technical problem of ion migration in perovskite thin films leading to day and night cycle light fatigue in solar cells in the prior art.

[0006] A first aspect of the present invention provides a method for preparing a functional modular perovskite thin film, comprising the following steps:

[0007] The first perovskite unit layer is formed;

[0008] A second perovskite cell layer is formed on the surface of the first perovskite cell layer to obtain a two-dimensional / three-dimensional functional perovskite thin film.

[0009] The first perovskite element layer and the second perovskite element layer are stacked on the surface of the above two-dimensional / three-dimensional functional perovskite thin film to obtain a multilayer functional element ordered perovskite thin film in which the two-dimensional perovskite element layer and the three-dimensional perovskite element layer are stacked in an orderly alternating manner.

[0010] In the above-mentioned multilayer functional modular perovskite thin film, the number of two-dimensional perovskite modular layers and the number of three-dimensional perovskite modular layers are ≥2, respectively.

[0011] A second aspect of the present invention provides a functional modular ordered perovskite thin film, which is obtained by the preparation method of the functional modular ordered perovskite thin film provided in the first aspect of the present invention.

[0012] A third aspect of the present invention provides a functional modular perovskite solar cell device, comprising a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode stacked sequentially. The perovskite light-absorbing layer is the functional modular perovskite thin film provided in the second aspect of the present invention, and the surface of the two-dimensional perovskite modular layer of the functional modular perovskite thin film is in contact with the hole transport layer to suppress halide ion migration.

[0013] Compared with the prior art, the beneficial effects of the present invention include:

[0014] This invention constructs a functionally ordered perovskite thin film by orderly alternating stacking of two-dimensional (2D) and three-dimensional (3D) perovskite units. Two-dimensional perovskite unit layers are inserted between two 3D perovskite unit layers. Through the ordered functional units, the 2D perovskite units confine halide ions within the limited space of the 3D perovskite layers. With the increase in the number of 2D perovskite barrier unit layers, the cyclic migration of halide ions within the 3D perovskite layer gradually decreases under day-night alternation, thereby enhancing the operational stability of the perovskite solar cell and mitigating device fatigue behavior. Through the orderly stacking of 2D / 3D perovskites and the optimization and matching of the unit structures, it is expected to fundamentally solve many stability problems caused by ion migration. Furthermore, this invention addresses the problem of polar solvent erosion of the perovskite thin film by alternating solution methods and chemical vapor deposition, achieving the ordered deposition of multilayer perovskite units. Attached Figure Description

[0015] Figure 1 A model diagram of a bilayer functional modular perovskite solar cell;

[0016] Figure 2 The image shows a cross-sectional SEM image of the three-dimensional perovskite solar cell prepared in Example 1.

[0017] Figure 3 SEM cross-sectional images of the monolayer two-dimensional / three-dimensional functional modular perovskite solar cells prepared in Example 2;

[0018] Figure 4 SEM cross-sectional view of the bilayer two-dimensional / three-dimensional functional modular perovskite solar cell prepared in Example 3;

[0019] Figure 5 The image shows the SEM cross-section of the three-layer two-dimensional / three-dimensional functional modular perovskite solar cell prepared in Example 4.

[0020] Figure 6 The JV (current-voltage) test curves are for the perovskite solar cells prepared in Examples 1-4.

[0021] Figure 7The stability test curves for the perovskite solar cell prepared in Example 1 are shown.

[0022] Figure 8 The stability test curves for the perovskite solar cell prepared in Example 2 are shown.

[0023] Figure 9 The stability test curves for the perovskite solar cell prepared in Example 3 are shown.

[0024] Figure 10 The light-dark cycle test curve of the perovskite solar cell prepared in Example 1;

[0025] Figure 11 The light-dark cycle test curve of the perovskite solar cell prepared in Example 2;

[0026] Figure 12 The light-dark cycle test curve of the perovskite solar cell prepared in Example 3;

[0027] Figure 13 The light-dark cycle test curve of the perovskite solar cell prepared in Example 4;

[0028] Figure 14 The light-dark cycle test curves are for the perovskite solar cell prepared in Example 5. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Please see Figure 1 The first aspect of the present invention provides a method for preparing a functional modular perovskite thin film, comprising the following steps:

[0031] S1, forming the first perovskite unit layer;

[0032] S2. A second perovskite cell layer is formed on the surface of the first perovskite cell layer to obtain a two-dimensional / three-dimensional functional perovskite thin film.

[0033] S3. A first perovskite element layer and a second perovskite element layer are stacked on the surface of the above two-dimensional / three-dimensional functional perovskite thin film to obtain a multilayer functional element ordered perovskite thin film in which two-dimensional perovskite element layers and three-dimensional perovskite element layers are stacked in an orderly alternating manner.

[0034] In this invention, if the first perovskite cell layer is a three-dimensional perovskite cell layer, then the second perovskite cell layer is a two-dimensional perovskite cell layer; if the first perovskite cell layer is a two-dimensional perovskite cell layer, then the second perovskite cell layer is a three-dimensional perovskite cell layer. This invention does not impose any restrictions on this.

[0035] This invention involves the orderly insertion of two-dimensional perovskite building blocks into the spaces between three-dimensional perovskites, dividing the three-dimensional perovskite into thin layers separated by two-dimensional perovskites. This confines ion migration within these thin layers. When the perovskite solar cell is subjected to day-night cycles, halide ions can only move within a relatively small space, ensuring they return to their original positions at night and preventing the creation of halogen vacancies. Furthermore, this strategy also prevents the accumulation of large numbers of charged ions at the cell interface. This structural design targeting the perovskite itself not only effectively improves device interface stability but also addresses the intrinsic instability of perovskite at its source, effectively mitigating fatigue in perovskite solar cells and enabling the fabrication of stable and efficient perovskite solar cell devices suitable for commercial applications.

[0036] In this invention, the number of two-dimensional perovskite element layers and three-dimensional perovskite element layers in the above-mentioned multilayer functional modular perovskite thin film is ≥2, for example, it can be 2 layers, 3 layers, 4 layers, etc., preferably 2 layers.

[0037] This invention does not limit the thickness of the two-dimensional and three-dimensional perovskite modular layers, and those skilled in the art can choose according to the actual situation. However, those skilled in the art should understand that an excessively high proportion of the thickness of the two-dimensional perovskite modular layer will reduce the photoelectric conversion efficiency, and an excessively high proportion of the thickness of the three-dimensional perovskite modular layer will reduce stability and fatigue resistance. In some preferred embodiments of this invention, the thickness of a single-layer two-dimensional perovskite modular layer is 10–50 nm.

[0038] In this invention, the components of the three-dimensional perovskite unit include, but are not limited to, MAPbI3, FAPbI3, and FA. 1-x MA x PbI 3- y Br y FA 1-x MA x PbI 3-y Br y Cs x FA 1-x PbI 3-y Br y Cs z FA 1-x MA x PbI 3-y Br y、Rb z Cs x FA 1-x PbI 3-y Br y And so on, where x, y = 0 to 1, z = 0 to 0.2.

[0039] In this invention, the raw materials for forming the two-dimensional perovskite basic layer include, but are not limited to, octylammonium bromide, octylammonium iodide, phenylethylammonium bromide, phenylethylammonium iodide, phenylbutylammonium iodide, propylammonium iodide, butylammonium iodide, isobutylammonium iodide, tert-butylammonium iodide, tert-butylammonium iodide, tert-butylammonium bromide, dodecylammonium iodide, cyclopropylammonium, 2-chloroethylammonium iodide, ethylenediamine dihydroiodate, 2-(methylthio)chloroethylammonium, 5-aminovalerate hydroiodate, pentafluorophenylethylammonium iodide, p-tert-butylphenylethylammonium iodide, 1-naphthylmethylammonium iodide, tetra-n-propylammonium iodide, guanidine hydroiodate, guanidine hydrobromide, etc., and the solvents are chloroform, isopropanol, etc.

[0040] In some specific embodiments of the present invention, the first perovskite unit layer is a three-dimensional perovskite unit layer. This first three-dimensional perovskite unit layer can be prepared using a solution method or a non-solution method (i.e., a dry method), and the present invention does not limit this. All other three-dimensional perovskite unit layers besides the first three-dimensional perovskite unit layer must be prepared using a non-solution method to avoid the erosion of the perovskite film by polar solvents. Further, the solution method includes, but is not limited to, spin coating, blade coating, spray coating, slot coating, etc., while the non-solution method includes, but is not limited to, chemical vapor deposition, vacuum evaporation, etc.

[0041] In some more specific embodiments of the present invention, the first perovskite modular layer is a three-dimensional perovskite modular layer, which is prepared by spin coating. The steps are as follows: first, spin coating at 1000-1500 rpm for 10-15 seconds, then spin coating at a high speed of 5000-6000 rpm for 30-50 seconds; at the 20th-25th second of high speed, add 120-150 μL of ethyl acetate as an anti-solvent; after spin coating, heat and anneal at 100-150°C for 30-60 minutes. During this process, the precursor concentration is 0.3-1.5 M, more preferably 0.6-1.2 M, and the solvent is at least one selected from N-formyldimethylamine, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and 1-methyl-2-pyrrolidone (NMP).

[0042] In other specific embodiments of the present invention, the second perovskite modular layer is a three-dimensional perovskite modular layer. All three-dimensional perovskite modular layers must be prepared using a non-solution method to avoid the corrosion of the perovskite film by polar solvents. Furthermore, the non-solution method includes, but is not limited to, chemical vapor deposition and vacuum evaporation.

[0043] In some preferred embodiments of the present invention, the three-dimensional perovskite modular layer is prepared by chemical vapor deposition with a pre-introduced transition phase, as follows:

[0044] Cesium halide and lead halide are deposited sequentially on a substrate; wherein the thickness of cesium halide is 10-20 nm and the thickness of lead halide is 100-200 nm.

[0045] A formamidinium halide solution was uniformly sprayed onto a glass cover plate, which was then placed over a thin film containing deposited cesium halide and lead halide. The film was then reacted in a high-temperature reactor using formamidinium halide vapor to form three-dimensional perovskite units. The concentration of the formamidinium halide solution was 0.2–0.7 M, the solvent was at least one of ethanol or isopropanol, and the volume was 10–30 mL. A nitrogen spray gun was used for spraying, with a nitrogen pressure of 0.3–0.8 MPa, and the area of ​​the glass cover plate was 130–160 cm². 2 The distance between the glass cover and the deposited cesium halide and lead halide films is 40–90 μm; the temperature of the high-temperature reactor is 140–160 °C, the reaction time is 10–20 min, and the pressure in the furnace chamber is maintained at 50–70 Pa.

[0046] In this invention, the two-dimensional perovskite matrix layer can be prepared using solution-based or non-solution-based methods, and this invention does not limit the method. Further, solution-based methods include, but are not limited to, spin coating, blade coating, spray coating, and slot coating, while non-solution-based methods include, but are not limited to, chemical vapor deposition and vacuum evaporation.

[0047] In some specific embodiments of the present invention, a two-dimensional perovskite basic layer is prepared by spin coating, and the steps are as follows: the precursor concentration is 5-30 mM; dynamic spin coating is performed with a spin coater speed of 4000-6000 rpm for 20-30 s; and finally, annealing is carried out at 100-120℃ for 5-10 min.

[0048] The inventors discovered that when using conventional solution methods to prepare such multilayered 3D / 2D stacked structures, the solvent used for the second 3D perovskite modular layer corrodes the underlying film. This is because conventional solution methods inevitably require the use of polar solvents such as N-formyldimethylamine, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and 1-methyl-2-pyrrolidone (NMP), which completely dissolve the first 2D / 3D functional modular perovskite film. Therefore, only dry preparation processes can avoid the use of polar solvents. Chemical vapor deposition (CVD) is a mature film-forming process that does not use any polar solvents during preparation, thus holding promise for preparing the upper 2D / 3D functional modular perovskite film. Furthermore, the perovskite growth rate in CVD is limited by the ion exchange rate at the reaction zone / organic atmosphere interface and the ion migration rate within the inorganic components. Therefore, the perovskite films prepared by this method usually contain supersaturated phases and some incompletely reacted inorganic components, which seriously affects the crystal quality of the film. To solve this problem, this invention introduces a transition phase during the construction of the upper three-dimensional perovskite unit layer by chemical vapor deposition to accelerate the migration and exchange rate of ions in the film, thus protecting the lower unit layer while obtaining a high-quality, uniform film.

[0049] A second aspect of the present invention provides a functional modular ordered perovskite thin film, which is obtained by the preparation method of the functional modular ordered perovskite thin film provided in the first aspect of the present invention.

[0050] A third aspect of the present invention provides a functional modular perovskite solar cell device, comprising a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode stacked sequentially. The perovskite light-absorbing layer is the functional modular perovskite thin film provided in the second aspect of the present invention, and the surface of the two-dimensional perovskite modular layer of the functional modular perovskite thin film is in contact with the hole transport layer to suppress halide ion migration.

[0051] In some specific embodiments of the present invention, the substrate is indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO).

[0052] In some specific embodiments of the present invention, the electron transport layer includes any one or more of titanium dioxide, tin dioxide, zinc oxide, and fullerene derivatives (PCBM).

[0053] In some specific embodiments of the present invention, the hole transport layer comprises any one or more of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), nickel oxide, copper oxide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), 3-hexyl-substituted polythiophene (P3HT).

[0054] In some specific embodiments of the present invention, the effective active area of ​​the functional modular perovskite solar cell under illumination is 0.148 cm². 2 .

[0055] In some embodiments of the present invention, the electrode is a gold electrode.

[0056] To avoid redundancy, in the following embodiments of the present invention, except for Spiro-OMeTAD from Youxuan Technology and hydrochloric acid from Sinopharm, all other pharmaceutical brands are Sigma-Aldrich; the perovskite solar cells were tested using a Keithley 2400, with the light source being a solar simulator (Oriel) equipped with a xenon lamp, and the incident light intensity was calibrated to 100 mW / cm² using a standard silicon cell. 2 (AM1.5).

[0057] Example 1

[0058] Step 1: Place the FTO conductive glass (sheet resistance: 10Ωsq) -1 The ultrasonic cleaner is then sequentially cleaned with deionized water, detergent (Hellmanex detergent), and anhydrous ethanol in an ultrasonic oscillator, and then dried with an air gun before use.

[0059] Step 2: Add 1.096g of stannous chloride dihydrate, 100μL of mercaptoacetic acid, 5g of urea and 5mL of concentrated hydrochloric acid to 400mL of deionized water in sequence, stir well to obtain mixed mother liquor A.

[0060] Step 3: Place the FTO glass cleaned in Step 1 into a UV cleaner for ozone oxidation for 15 minutes; dilute mother liquor A with deionized water at a volume ratio of 1:5 to obtain solution B (concentration of 12mM); immerse the FTO glass in solution B and heat at 90℃ for 3 hours to obtain a dense SnO2 layer.

[0061] Step 4: Prepare a 1.5M three-dimensional perovskite precursor solution with FA as the component. 0.98 MA 0.02 PbI 2.85 Br 0.15A mixed solvent of DMF and DMSO (v:v = 8:1) was used to spread the perovskite precursor solution onto the FTO / SnO2 substrate obtained in step 3. Spin coating was performed in segments: low speed 1000 rpm for 10 s, high speed 5000 rpm for 30 s, and 120 μL of ethyl acetate antisolvent was added dropwise at the 20th second of high speed. After spin coating, the film was annealed at 100 °C for 60 min to obtain a perovskite film with a thickness of about 600 nm.

[0062] Step 5: Preparation of hole transport layer solution: Dissolve 70 mg Spiro-OMeTAD powder, 25 μL tert-butylpyridine, 20 μL lithium bis(trifluoromethylsulfonyl)imide (500 mg / mL acetonitrile solution), and 15 μL tris[4-tert-butyl-2-(1H-pyrazol-1-yl)pyridine]cobalt-tris(1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide salt (300 mg / mL acetonitrile solution) in 1 mL chlorobenzene solution in sequence, stir well, and obtain Spiro-OMeTAD solution.

[0063] Step 6: Spin-coat the Spiro-OMeTAD solution onto the surface of the perovskite film obtained in Step 4, and spin-coat at 3000 rpm for 20 s to obtain the hole transport layer.

[0064] Step 7: Attach a photomask to the surface of the hole transport layer to achieve a perovskite photoactive area of ​​0.148 cm². 2 Then, 100nm of gold is deposited as the counter electrode.

[0065] Example 2

[0066] The only difference between Example 2 and Example 1 is the preparation process of the perovskite thin film, as detailed below:

[0067] Step 41: Prepare a 1.5M three-dimensional perovskite precursor solution with the following composition: FA 0.98 MA 0.02 PbI 2.85 Br 0.15 A mixed solvent of DMF and DMSO (v:v = 8:1) was used to spread the above perovskite precursor solution on the surface of the FTO / SnO2 substrate obtained in step 3. The perovskite was spin-coated in segments, running at a low speed of 1000 rpm for 10 s and a high speed of 5000 rpm for 30 s. At the 20th second of the high speed, 120 μL of ethyl acetate antisolvent was added dropwise. After spin-coating, the perovskite was annealed at 100 °C for 60 min to obtain a three-dimensional perovskite matrix layer with a thickness of about 600 nm.

[0068] Step 42: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto the three-dimensional perovskite matrix layer at a speed of 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a two-dimensional / three-dimensional perovskite film with a thickness of approximately 600 nm.

[0069] Example 3

[0070] The only difference between Example 3 and Example 1 is the preparation process of the perovskite thin film, as detailed below:

[0071] Step 41: Prepare a 0.9 M three-dimensional perovskite precursor solution with the following composition: FA 0.98 MA 0.02 PbI 2.85 Br 0.15 A mixed solvent of DMF and DMSO (v:v = 8:1) was used to spread the above perovskite precursor solution on the surface of the FTO / SnO2 substrate obtained in step 3. The perovskite was spin-coated in segments, running at a low speed of 1000 rpm for 10 s and a high speed of 5000 rpm for 30 s. At the 20th second of the high speed spin-coating, 120 μL of ethyl acetate antisolvent was added dropwise. After spin-coating, the perovskite was annealed at 100 °C for 60 min to obtain a three-dimensional perovskite matrix layer with a thickness of about 300 nm.

[0072] Step 42: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto the three-dimensional perovskite matrix layer at a speed of 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a two-dimensional / three-dimensional perovskite film with a thickness of approximately 300 nm.

[0073] Step 43: 20 nm CsBr and 200 nm PbI2 are sequentially deposited on two-dimensional / three-dimensional perovskite films using a dual-source co-evaporation method at a deposition rate of [missing information]. Vacuum degree is 8×10 -6 Pa; Dissolve 0.8 g FAI and 0.2 g FACl in 20 mL of ethanol, and spray the solution onto an area of ​​144 cm². 2 On a glass cover plate, the glass cover plate was placed on the CsBr / PbI2 film with a distance of 50 μm between them. Then, it was placed in a high-temperature reactor at 150℃. After the vacuum was evacuated to 50 Pa, the reaction was carried out for 10 min to obtain a three-dimensional / two-dimensional / three-dimensional perovskite film with a thickness of about 600 nm.

[0074] Step 44: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto a 3D / 2D / 3D perovskite film at 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a 2D / 3D / 2D / 3D perovskite film with a thickness of approximately 600 nm.

[0075] Example 4

[0076] The only difference between Example 4 and Example 1 is the preparation process of the perovskite thin film, as detailed below:

[0077] Step 41: Prepare a 0.7M three-dimensional perovskite precursor solution with the following composition: FA 0.98 MA 0.02 PbI 2.85 Br 0.15 A mixed solvent of DMF and DMSO (v:v = 8:1) was used to spread the above perovskite precursor solution on the surface of the FTO / SnO2 substrate obtained in step 3. The perovskite was spin-coated in segments, running at a low speed of 1000 rpm for 10 s and a high speed of 5000 rpm for 30 s. At the 20th second of the high speed, 120 μL of ethyl acetate antisolvent was added dropwise. After spin-coating, the perovskite was annealed at 100 °C for 60 min to obtain a three-dimensional perovskite unit layer with a thickness of about 200 nm.

[0078] Step 42: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto the three-dimensional perovskite matrix layer at a speed of 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a two-dimensional / three-dimensional matrix perovskite film with a thickness of approximately 200 nm.

[0079] Step 43: 13 nm CsBr and 130 nm PbI2 were sequentially deposited on two-dimensional / three-dimensional perovskite films using a dual-source co-evaporation method at a deposition rate of [missing information]. Vacuum degree is 8×10 -6 Pa; Dissolve 0.8 g FAI and 0.2 g FACl in 20 mL of ethanol, and spray the solution onto an area of ​​144 cm². 2 On a glass cover plate, the glass cover plate is placed on the CsBr / PbI2 film with a distance of 50μm between them. Then, it is placed in a high-temperature reactor at 150℃. After the vacuum is evacuated to 50Pa, the reaction is carried out for 10min to obtain a three-dimensional / two-dimensional / three-dimensional perovskite film with a thickness of about 400nm.

[0080] Step 44: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto a three-dimensional / two-dimensional / three-dimensional perovskite film at 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a two-dimensional / three-dimensional / two-dimensional / three-dimensional basic perovskite film with a thickness of approximately 400 nm.

[0081] Step 45: Again, using the dual-source co-evaporation method, deposit 13 nm CsBr and 130 nm PbI2 sequentially on the 2D / 3D / 2D / 3D perovskite thin films, at a deposition rate of [missing information]. Vacuum degree is 8×10 -6 Pa; Dissolve 0.8 g FAI and 0.2 g FACl in 20 mL of ethanol, and spray the solution onto an area of ​​144 cm². 2 On a glass cover plate, the glass cover plate is placed on the CsBr / PbI2 film with a distance of 50μm between them. Then, it is placed in a high-temperature reactor at 150℃. After the vacuum is evacuated to 50Pa, the reaction is carried out for 10min to obtain a three-dimensional / two-dimensional / three-dimensional / two-dimensional / three-dimensional perovskite film with a thickness of about 600nm.

[0082] Step 46: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto a 3D / 2D / 3D / 2D / 3D perovskite film at 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a 2D / 3D / 2D / 3D / 2D / 3D elementary perovskite film with a thickness of approximately 600 nm.

[0083] Example 5

[0084] The only difference between Example 5 and Example 1 is the preparation process of the perovskite thin film, as detailed below:

[0085] Step 41: 35 nm CsBr and 350 nm PbI2 were sequentially deposited on an FTO / SnO2 substrate using a dual-source co-evaporation method at a deposition rate of [missing information]. Vacuum degree is 8×10 -6 Pa; Dissolve 0.8 g FAI and 0.2 g FACl in 20 mL of ethanol, and spray the solution onto an area of ​​144 cm². 2 On a glass cover plate, the glass cover plate was placed on the CsBr / PbI2 film with a distance of 50 μm between them. Then, it was placed in a high-temperature reactor at 150℃. After the vacuum was reduced to 50 Pa, the reaction was carried out for 10 min to obtain a three-dimensional perovskite film with a thickness of about 600 nm.

[0086] Step 42: Prepare a 10 mM octylammonium bromide solution in chloroform; spin-coat the octylammonium bromide solution onto a three-dimensional perovskite film at 5000 rpm for 30 s, and then anneal at 100 °C for 5 min to obtain a two-dimensional / three-dimensional elementary perovskite film with a thickness of approximately 600 nm.

[0087] Please see Figure 2 , Figure 2 This is a SEM cross-sectional image of the three-dimensional perovskite solar cell prepared in Example 1. (The image is obtained through...) Figure 2 It can be seen that the perovskite grains penetrate directly through the entire perovskite photoactive layer.

[0088] Please see Figure 3 , Figure 3This is a SEM cross-sectional image of the monolayer two-dimensional / three-dimensional functional modular perovskite solar cell prepared in Example 2. Figure 3 It can be seen that the monolayer two-dimensional / three-dimensional functional modular perovskite films have larger grain sizes, which is attributed to the passivation effect of octylammonium bromide on the three-dimensional perovskite films.

[0089] Please see Figure 4 , Figure 4 This is a SEM cross-sectional image of the bilayer two-dimensional / three-dimensional functional modular perovskite solar cell prepared in Example 3. Figure 4 It can be seen that there is a clear boundary between the two three-dimensional perovskite unit layers, and the boundary is a two-dimensional perovskite unit layer barrier layer.

[0090] Please see Figure 5 , Figure 5 The image shows a SEM cross-section of the three-layer two-dimensional / three-dimensional functional modular perovskite solar cell prepared in Example 4. Compared to other examples, the perovskite film in this example has relatively small grains.

[0091] Please see Figure 6 , Figure 6 The JV test curves are for the perovskite solar cells prepared in Examples 1-4. (The text abruptly ends here.) Figure 6 It can be seen that the solar cell fabricated from the single-layer two-dimensional / three-dimensional functional modular perovskite thin film prepared in Example 2 has the best photoelectric conversion efficiency (20.9%), which is related to the passivation of the three-dimensional perovskite surface. The efficiency of the bilayer two-dimensional / three-dimensional functional modular perovskite cell prepared in Example 3 is 20.6%, which is not much different from the efficiency of the three-dimensional perovskite cell prepared in Example 1 (20.2%). In contrast, the efficiency of the three-layer two-dimensional / three-dimensional functional modular perovskite device is much lower than that of the other devices, with an efficiency of only 18.5%.

[0092] Please see Figures 7-9 , Figures 7-9 The stability test curves for the perovskite solar cells prepared in Examples 1-3 are shown respectively. Figures 7-9 It can be seen that after 200 hours of stability testing, the initial efficiency values ​​of the three-dimensional perovskite solar cells and the monolayer two-dimensional / three-dimensional functional modular perovskite solar cells prepared in Examples 1 and 2 decreased by 20% and 17%, respectively, after 200 hours. Figures 7-8 Perovskite solar cells fabricated using bilayer ordered modular units exhibit excellent operational stability, maintaining an efficiency of over 90% of their initial value. Figure 9 ).

[0093] Please see Figures 10-14 , Figures 10-14 The light-dark cycle test curves are for the perovskite solar cells prepared in Examples 1-5. (The text abruptly ends here.) Figures 10-14 It can be seen that the perovskite solar cells prepared in Examples 1, 2 and 5 exhibit significant fatigue after 200 hours of light-dark cycling, while the perovskite solar cells prepared in Examples 3 and 4 using multilayer ordered modular units exhibit negligible fatigue behavior. This fully demonstrates that constructing modular ordered perovskite structures can not only enhance the operational stability of perovskite devices, but also effectively alleviate the fatigue behavior of solar cells under light-dark cycling, which is of great significance for promoting the commercialization of perovskite solar cells.

[0094] In summary, this invention successfully constructed a multilayered two-dimensional / three-dimensional functional modular perovskite thin film by alternating solution methods and chemical vapor deposition. Two-dimensional perovskite modular layers are inserted between three-dimensional perovskite layers, effectively passivating the surface of the three-dimensional perovskite and reducing surface defects. Simultaneously, the two-dimensional perovskite modular layers confine halide ions within a specific three-dimensional perovskite space, and the movable space is further reduced with the increase in the number of two-dimensional perovskite modular layers. Compared with traditional three-dimensional and two-dimensional / three-dimensional perovskite solar cells, the multilayer modular perovskite solar cell exhibits good stability under standard sunlight irradiation. Furthermore, after prolonged light-dark cycling, three-dimensional and two-dimensional / three-dimensional perovskite solar cells exhibit significant fatigue behavior, while the multilayered two-dimensional / three-dimensional modular perovskite solar cell shows no fatigue phenomenon.

[0095] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a functional modular perovskite thin film, characterized in that, Includes the following steps: The first perovskite unit layer is formed; A second perovskite cell layer is formed on the surface of the first perovskite cell layer to obtain a two-dimensional / three-dimensional functional perovskite thin film. The first perovskite element layer and the second perovskite element layer are stacked on the surface of the two-dimensional / three-dimensional functional element perovskite film to obtain a multilayer functional element ordered perovskite film in which the two-dimensional perovskite element layer and the three-dimensional perovskite element layer are stacked in an orderly alternating manner. The number of two-dimensional perovskite primitive layers and the number of three-dimensional perovskite primitive layers in the multilayer functional modular perovskite thin film are ≥2, respectively.

2. The method for preparing a functional modular perovskite thin film according to claim 1, characterized in that, The components of the three-dimensional perovskite unit include MAPbI3, FAPbI3, and FA. 1-x MA x PbI 3-y Br y FA 1-x MA x PbI 3-y Br y Cs x FA 1-x PbI 3-y Br y Cs z FA 1-x MA x PbI 3-y Br y 、Rb z Cs x FA 1-x PbI 3-y Br y Any one or more of the following, where x, y = 0~1, z = 0~0.2; The raw materials forming the two-dimensional perovskite basic layer include any one or more of the following: octylammonium bromide, octylammonium iodide, phenylethylammonium bromide, phenylethylammonium iodide, phenylbutylammonium iodide, propylammonium iodide, butylammonium iodide, isobutylammonium iodide, tert-butylammonium iodide, tert-butylammonium iodide, tert-butylammonium bromide, dodecylammonium iodide, cyclopropylammonium, 2-chloroethylammonium iodide, ethylenediamine dihydroiodate, 2-(methylthio)chloroethylammonium, 5-aminovalerate hydroiodate, pentafluorophenylethylammonium iodide, p-tert-butylphenylethylammonium iodide, 1-naphthylmethylammonium iodide, tetra-n-propylammonium iodide, guanidine hydroiodate, and guanidine hydrobromide.

3. The method for preparing a functional modular perovskite thin film according to claim 1, characterized in that, The first perovskite element layer is a three-dimensional perovskite element layer. The first three-dimensional perovskite element layer is prepared by a solution method or a non-solution method. All other three-dimensional perovskite element layers except the first three-dimensional perovskite element layer are prepared by a non-solution method.

4. The method for preparing a functional modular perovskite thin film according to claim 3, characterized in that, The first perovskite modular layer is a three-dimensional perovskite modular layer. The first three-dimensional perovskite modular layer is prepared by spin coating, and the steps are as follows: First, rotate at 1000-1500 rpm for 10-15 s, then rotate at a high speed of 5000-6000 rpm for 30-50 s; add 120-150 μL of antisolvent dropwise at the 20th-25th s of high speed. After spin coating, heat and anneal at 100-150 ℃ for 30-60 min; wherein, the precursor concentration is 0.3-1.5 M, and the solvent is at least one of N-formyldimethylamine, dimethylformamide, dimethyl sulfoxide, and 1-methyl-2-pyrrolidone; the antisolvent is ethyl acetate.

5. The method for preparing a functional modular perovskite thin film according to claim 1, characterized in that, The second perovskite modular layer is a three-dimensional perovskite modular layer, and all three-dimensional perovskite modular layers are prepared by a non-solution method.

6. The method for preparing a functional modular perovskite thin film according to claim 1, characterized in that, The three-dimensional perovskite modular layer was prepared by chemical vapor deposition with a pre-introduced transition phase, and the steps are as follows: Cesium halide and lead halide are deposited sequentially on the substrate; wherein the thickness of cesium halide is 10~20 nm and the thickness of lead halide is 100~200 nm. A formamidinium halide solution was uniformly sprayed onto a glass cover plate, which was then placed over a thin film containing deposited cesium halide and lead halide. The film was then reacted in a high-temperature reactor using formamidinium halide vapor to form three-dimensional perovskite units. The concentration of the formamidinium halide solution was 0.2–0.7 M, the solvent was at least one of ethanol or isopropanol, and the volume was 10–30 mL. A nitrogen spray gun was used for spraying, with a nitrogen pressure of 0.3–0.8 MPa, and the area of ​​the glass cover plate was 130–160 cm². 2 The distance between the glass cover and the deposited cesium halide and lead halide films is 40-90 μm; the temperature of the high-temperature reactor is 140-160 °C, the reaction time is 10-20 min, and the pressure in the furnace chamber is maintained at 50-70 Pa.

7. The method for preparing a functional modular perovskite thin film according to claim 1, characterized in that, The two-dimensional perovskite modular layer was prepared by spin coating, and the steps are as follows: The precursor concentration was 5-30 mM; dynamic spin coating was performed with a spin coater speed of 4000-6000 rpm for 20-30 s, followed by annealing at 100-120 ℃ for 5-10 min.

8. A functional modular perovskite thin film, characterized in that, The functional modular perovskite thin film is obtained by the preparation method of the functional modular perovskite thin film according to any one of claims 1 to 7.

9. A functional modular perovskite solar cell device, characterized in that, The material comprises a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode, which are stacked sequentially. The perovskite light-absorbing layer is the functional modular perovskite thin film as described in claim 8, and the surface of the two-dimensional perovskite modular layer of the functional modular perovskite thin film is in contact with the hole transport layer.

10. The functional modular perovskite solar cell device according to claim 9, characterized in that, The substrate is indium-doped tin oxide or fluorine-doped tin oxide; the electron transport layer includes any one or more of titanium dioxide, tin dioxide, zinc oxide, and fullerene derivatives; the hole transport layer includes any one or more of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, nickel oxide, copper oxide, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine, and 3-hexyl-substituted polythiophene].

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