Highly transparent perovskite cell thin film and preparation method thereof

Abstract

The application provides a high-transparency perovskite battery thin film and a preparation method thereof, and belongs to the technical field of perovskite materials, and comprises the following steps: CNT net is deposited on the surface of a multilayer graphene thin film covered on PMMA, and then sequentially immersed in anhydrous ethanol and acetone, so that the graphene-CNT composite net is covered on the surface of a device substrate, and a substrate covered with the graphene-CNT composite net is obtained through hot pressing; in a nitrogen glove box, PbI2, FAI, CsI and MABr are added into a mixed solvent, sealed, stirred in the dark, N-(3-dimethylaminopropyl) methacrylamide is added and stirred to prepare a perovskite precursor solution; the substrate covered with the graphene-CNT composite net is preheated, the perovskite precursor solution and anhydrous chlorobenzene are sequentially dropped on the surface of the graphene-CNT composite net for spin coating, and the high-transparency perovskite battery thin film is prepared through temperature rising and cooling. The application can improve the light transmittance of the thin film and has good photoelectric conversion efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite materials, and particularly relates to a high-transparency perovskite battery thin film and a preparation method thereof. BACKGROUND

[0002] With the promotion of energy utilization rate and green energy concept, semi-transparent perovskite solar cells have gradually become a research hotspot, especially in the fields of automobiles and intelligent electronic devices, and their application potential has attracted much attention. Compared with traditional opaque photovoltaic devices, semi-transparent devices have significant advantages in terms of light transmission, and can provide good charge collection capability and photoelectric conversion efficiency while ensuring a certain degree of transparency. However, due to their transparent nature, semi-transparent perovskite solar cells will face the problem of photocurrent loss, mainly due to the contradiction between light transmission and charge collection performance. Therefore, how to ensure the visible light transmittance while improving the photoelectric conversion efficiency of the battery has become a key problem to be solved in this field.

[0003] Perovskite solar cells have become a research focus in the photovoltaic field in recent years due to their low cost, high efficiency and solution processable characteristics. However, the stability problem of halide perovskite materials is still an important factor restricting their large-scale application. Especially in Br / I perovskite materials, the migration of halide ions leads to serious photo-induced phase separation and defect formation, which in turn affects the photoelectric performance. The loss of photocurrent, the decrease of open-circuit voltage (VOC) and fill factor (FF), and other problems seriously limit the long-term stability and efficiency of perovskite solar cells. In order to solve this problem, researchers have designed various additives to adjust the crystallization process of perovskite, improve the quality of the grain, and reduce the generation of defects.

[0004] The patent application file with the publication number CN106784330A discloses a kind of translucent organic metal halide perovskite thin film solar cell and preparation method thereof, by adding vinylidene fluoride-hexafluoropropylene copolymer to organic metal halide perovskite precursor solution, promote perovskite precursor and solvent molecule form intermediate, and slow down the conversion of intermediate to perovskite in spin coating and annealing process, make perovskite layer pinhole reduce, grain size increase, grain boundary reduce, surface is more smooth and fluorescence lifetime improves, so as to realize the efficiency of semi-transparent perovskite solar cell below 150nm of photoactive layer is improved.But vinylidene fluoride-hexafluoropropylene copolymer as insulator, although can improve film formation, but will hinder the charge transport inside perovskite layer, increase series resistance, have negative influence to FF;In addition, by adding vinylidene fluoride-hexafluoropropylene copolymer in spin coating and annealing process, mainly focus on the regulation of crystallization process to improve film formation quality, but it cannot avoid the essential problem of internal defect formation due to halogen ion migration;At the same time, simply by thinning perovskite layer thickness to improve transparency, will inevitably sacrifice a part of light absorption capacity, so that the battery efficiency will not be very high.

[0005] Therefore, it is necessary to provide a high-transparency perovskite battery thin film and a preparation method thereof to solve the problems existing in the prior art. SUMMARY

[0006] Therefore, the present application provides a high-transparency perovskite battery thin film and a preparation method thereof, which can improve the light transmittance of the thin film while having good photoelectric conversion efficiency.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation method of a high-transparency perovskite battery thin film, comprising the following steps:

[0008] S1, depositing a CNT net on the surface of a multi-layer graphene thin film covered on PMMA, respectively immersing in anhydrous ethanol and acetone in sequence, obtaining a graphene-CNT composite net, immersing in deionized water, taking out with a polytetrafluoroethylene sheet, covering on the surface of a device substrate, hot pressing, cooling, peeling off the polytetrafluoroethylene sheet, and obtaining a substrate covered with a graphene-CNT composite net;

[0009] S2, in a nitrogen glove box, adding PbI2, FAI, CsI and MABr into a mixed solvent, sealing the container, stirring in the dark, adding N-(3-dimethylaminopropyl) methacrylamide and continuing to stir, filtering, and preparing a perovskite precursor solution;

[0010] S3, preheating the substrate covered with the graphene-CNT composite net, dropping the perovskite precursor solution and anhydrous chlorobenzene on the surface of the graphene-CNT composite net in sequence for spin coating, heating, and cooling to room temperature, and preparing a high-transparency perovskite battery thin film.

[0011] The graphene-CNT composite network is prepared by interweaving the sheet structure of graphene and the fiber structure of carbon nanotubes (CNT) to form a porous network, which is embedded in a high-transparency perovskite film. Graphene has excellent planar conductivity, and CNT provides high-conductivity channels. The combination of the two forms a three-dimensional high-conductivity network to provide efficient electron / hole transport channels, so that electrons / holes can move quickly along the graphene-CNT composite network, shorten the charge transport path, reduce the recombination loss of carriers in the film, and improve the open-circuit voltage (Voc) and fill factor (FF). The porous network in the graphene-CNT composite network has a micropore / nanopore structure, which can allow light to directly pass through the composite skeleton, optimize the overall film transmittance without reducing the thickness of the perovskite film, and further ensure that the overall photoelectric conversion efficiency does not decrease. In addition, the graphene-CNT composite network forms a strong skeleton by interweaving graphene and CNT, and the stress is dispersed by the porous network structure, so that the film can still maintain good integrity under external force.

[0012] The present application introduces a bifunctional N-(3-dimethylaminopropyl) methacrylamide (DPM) into the perovskite precursor solution, which suppresses ion migration and phase separation while improving the overall photoelectric conversion efficiency and long-term stability. The DPM monomer contains multiple functional groups, among which the C=C bond can be polymerized to form a polymer chain (PDPM) located at the perovskite grain boundary during the thermal annealing process of the perovskite film. PDPM forms a polymer barrier with covalent and non-covalent bonds, which suppresses the migration of halide ions in the perovskite layer, thereby reducing the performance degradation caused by ion migration. In addition, the amide group of PDPM coordinates with PbI2 in the perovskite component to form a strong interaction, promoting the ordered growth of perovskite crystals, passivating grain boundaries and surface defects, and further reducing the path of ion migration to avoid non-radiative recombination loss. Furthermore, DPM forms a strong hydrogen bonding interaction with MA + , inhibits the deprotonation of MA + , stabilizes MA in the cation form in the precursor, avoids the condensation reaction between MA and FA + , reduces the formation of impurities, and also improves the storage stability of the precursor.

[0013] The polymer chain of DPM forms a composite structure with the perovskite layer, enhancing the overall toughness of the film. The synergistic effect of the graphene-CNT composite network and the polymer network effectively improves the mechanical stress resistance of the film, avoiding the generation of cracks. The combination of the two enhances the uniformity and crystallinity of the final film, reduces the defect density, and further improves the overall photoelectric conversion efficiency.

[0014] Optionally, the multi-layer graphene film covered on PMMA is prepared by dropping a 5% poly(methyl methacrylate) solution onto the Cu-based graphene surface, spin-coating at a speed of 1000 rpm for 20 s, baking on a hot plate at 150-180 ℃ for 2-5 min, immersing in a copper etching solution with a molar concentration of 0.5-2 mol / L for 30-60 min, rinsing with deionized water for 3-5 times, obtaining the graphene film covered on PMMA, immersing in deionized water, taking out the graphene film covered on PMMA with another Cu-based graphene, blowing dry the surface moisture, heating at 80-100 ℃ for 5-10 min, immersing in the copper etching solution with a molar concentration of 0.5-2 mol / L for 30-60 min, rinsing with deionized water for 3-5 times, and obtaining the multi-layer graphene film covered on PMMA.

[0015] The multi-layer graphene film covered on PMMA is prepared by using a wet transfer combined with a lamination technology in the application, and the PMMA film spin-coated on the Cu-based graphene forms a firm, continuous and flexible support layer after solidification, which effectively avoids tearing and wrinkling of the graphene film in subsequent operations; the heating step can evaporate the residual moisture, and at the same time, the π-π interaction between the two layers of graphene is enhanced by heat induction, so that the two layers of graphene are tightly combined to form a more stable structure.

[0016] Optionally, the Cu-based graphene is obtained by placing a copper foil substrate into a tube furnace, keeping an argon atmosphere, heating the furnace to 1030 ℃, introducing hydrogen gas for 20 min, keeping the temperature and hydrogen flow rate unchanged, introducing methane gas at a pressure of 9 Torr for 10 min, closing the methane gas, keeping the hydrogen and argon atmosphere, rapidly cooling to below 500 ℃, and when the temperature drops to 200 ℃, closing the hydrogen and only keeping the argon gas flow, and cooling to room temperature.

[0017] Optionally, the flow rate of the argon gas is 100 sccm, the flow rate of the hydrogen gas is 50 sccm, and the flow rate of the methane gas is 7 sccm.

[0018] Optionally, the CNT net is obtained by grabbing a bundle of carbon nanotubes at the edge of a carbon nanotube array with a clamp, starting a precision manipulator, and horizontally stretching at a speed of 1-5 mm / s.

[0019] The carbon nanotube array is obtained by placing a SiO2 / Si substrate with deposited FeCl2 catalyst into a tube furnace, keeping an argon atmosphere with a flow rate of 100 sccm, heating the furnace to 800 ℃, introducing acetylene gas with a flow rate of 10 sccm at a pressure of 9 Torr for 15 min, closing the acetylene gas, keeping the argon atmosphere, and cooling to room temperature.

[0020] In the process of chemical vapor deposition growth of carbon nanotubes (CNT), adjacent carbon nanotubes are attracted and supported by van der Waals force, and self-organize to form a highly ordered and densely arranged carbon nanotube array; when a bundle of CNT is horizontally stretched, the outermost CNT is pulled out, and due to the strong van der Waals force with the adjacent CNT, the adjacent CNT is also pulled out, the pulled-out CNT bundle automatically expands, opens, overlaps with each other in the air, and forms a semi-transparent net-shaped film, that is, a CNT net.

[0021] Optionally, in the step S1, the CNT net is directly deposited on the surface of the multilayer graphene film covered on the PMMA by using a dry spinning device, the CNT net is deposited twice by cross-stacking, immersed in anhydrous ethanol for 15-30 min, taken out, dried at room temperature, immersed in acetone for 2-5 h, and a graphene-CNT composite net is obtained, the graphene-CNT composite net is covered on the surface of a device substrate, and the graphene-CNT composite net is placed in a hot press at a pressure of 0.1 MPa and kept at 60-80 DEG C for 10 min, and then cooled to room temperature, and the polytetrafluoroethylene sheet is peeled off to obtain a substrate covered with the graphene-CNT composite net.

[0022] The graphene-CNT composite net formed by cross-stacking twice is more dense, and the isotropy of in-plane conductivity is ensured; and the CNT network becomes dense and firm by using the low surface tension of anhydrous ethanol, and the graphene-CNT composite network is further closely attached to the lower graphene, so that the mechanical strength of the graphene-CNT composite network is significantly enhanced.

[0023] Optionally, in the step S2, MACl is further added when PbI2, FAI, CsI and MABr are added, and urea is further added when N-(3-dimethylaminopropyl) methacrylamide is added.

[0024] Urea and MACl are further added to cooperatively regulate crystallization and further perform defect passivation, MACl acts as a crystallization regulator, can form an intermediate phase (PbCl2) by a volatile template effect, delays the crystallization rate of perovskite in the initial stage of crystallization, and the delay effect helps to form larger grains, further reduces the number of grain boundaries and defects; meanwhile, the C=O and -NH2 functional groups in the urea molecule can strongly coordinate with uncoordinated Pb 2+ ions, passivate deep level defects, and affect the ion concentration and nucleation rate in the solution, promote grain growth, increase the grain size, and reduce the number of grain boundaries to reduce the defect density of the grain boundaries. 2+

[0025] ​Optionally, in step S2, 2.7-3 parts of PbI2 are added into the mixed solvent in a nitrogen glove box, mixed uniformly, then 0.8-1 parts of FAI, 0.1-0.15 parts of CsI, 0.02-0.03 parts of MABr, and 0.07-0.1 parts of MACl are added, the container is sealed, placed on a magnetic stirrer, stirred at a speed of 500-700 rpm in the dark for 10-15 h until a clear, transparent light yellow solution is obtained, 0.015-0.02 parts of urea and 0.001-0.0015 parts of N-(3-dimethylaminopropyl) methacrylamide are added for continuous stirring in the dark for 4-5 h, the solution is sucked using a syringe, filtered, and a perovskite precursor solution is prepared; the mixed solvent is DMSO and DMF, and the volume ratio of DMSO to DMF is 1:4.

[0026] Preferably, the filter used for filtering is an organic needle filter with a pore size of 0.22 μm.

[0027] Optionally, in step S3, the substrate covered with the graphene-CNT composite net is preheated on a hot stage at 100℃ for 1 min, 80-100 parts by volume of the perovskite precursor solution is added dropwise on the surface of the graphene-CNT composite net, spin-coated at a speed of 500-1000 rpm for 10 s, then spin-coated at a speed of 4000 rpm for 15-20 s, 120-150 parts by volume of anhydrous chlorobenzene is added dropwise, spin-coated at a speed of 4000 rpm for 10-20 s, kept at 100℃ for 10-15 min, heated to 150-160℃ for 10-12 min, and naturally cooled to room temperature, thereby preparing a high-transmittance perovskite battery thin film.

[0028] The application further provides a high-transmittance perovskite battery thin film.

[0029] The high-transmittance perovskite battery thin film prepared by the above method and proportion can achieve good light transmittance while avoiding the migration of halogen ions in the thin film, and improve the overall photoelectric conversion efficiency.

[0030] The above technical solution of the application at least has the following beneficial effects:

[0031] 1. The graphene-CNT composite net is prepared, which combines the planar conductivity of graphene and the high-conductivity channel of CNT to form a three-dimensional high-conductivity network. This composite structure can effectively improve the transmission efficiency of electrons / holes, reduce the loss of carrier recombination, thereby improving the open-circuit voltage (Voc) and the fill factor (FF). The microporous / nanoporous structure of the composite net optimizes the light transmittance of the thin film while ensuring the photoelectric conversion efficiency. In addition, the graphene-CNT composite net provides a strong and tough skeleton, which can effectively disperse stress and maintain the integrity of the thin film.

[0032] 2、The application introduces a bifunctional group DPM in the perovskite precursor solution, and a polymer chain (PDPM) is formed by thermal annealing, which effectively suppresses ion migration and phase separation, and improves efficiency and long-term stability. PDPM forms a polymer barrier at the grain boundary through covalent and non-covalent bonds, reduces battery performance decline, promotes crystal ordered growth and passivates grain boundary defects. At the same time, DPM forms hydrogen bonds with MA + , stabilizes the cation form, avoids impurity formation, and improves the storage stability of the precursor.

[0033] 3、The synergistic effect of graphene-CNT composite network and DPM polymer network effectively improves the mechanical stress resistance of the thin film and avoids the generation of cracks. The finally prepared high-transparency perovskite battery thin film has significantly improved uniformity, crystallinity, photoelectric conversion efficiency and stability. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The scanning electron microscope image of the high-transparency perovskite battery thin film prepared in the present application comparative example 1;

[0035] Figure 2 The scanning electron microscope image of the high-transparency perovskite battery thin film prepared in the present application example 1;

[0036] Figure 3 The photoluminescence spectrum of the high-transparency perovskite battery thin film prepared in the present application example 1 and comparative example 2. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described below in combination with the embodiments of the present application. The described embodiments are part of the embodiments of the present application, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present application belong to the scope of protection of the present application.

[0038] Preparation:

[0039] Put the copper foil substrate into the tube furnace, keep the argon atmosphere (100 sccm), heat the furnace temperature to 1030℃, then introduce hydrogen gas (50 sccm) for 20 min, keep the temperature and hydrogen flow unchanged, introduce methane gas (7 sccm) at a pressure of 9Torr, grow for 10 min, then turn off the methane gas, keep the hydrogen and argon atmosphere, quickly cool to below 500℃, when the temperature drops to 200℃, turn off the hydrogen, only keep the argon gas flow, cool to room temperature to get Cu-based graphene.

[0040] The SiO2 / Si substrate with deposited FeCl2 catalyst was placed in a tube furnace, under argon atmosphere (100 sccm), the furnace temperature was raised to 800℃, then acetylene gas (10 sccm) was introduced, and the growth was carried out for 15 min under a pressure of 9 Torr, the acetylene gas was turned off, and the argon atmosphere was maintained until the furnace was cooled to room temperature to obtain the carbon nanotube array.

[0041] Example 1

[0042] A 0.7 mL solution of polymethyl methacrylate with a mass concentration of 5% was dropped onto the surface of the Cu-based graphene, and spin-coated at a speed of 1000 rpm for 20 s, then baked on a hot plate at 150℃ for 5 min, immersed in a 300 mL ammonium persulfate solution with a molar concentration of 2 mol / L for 30 min, then washed with deionized water for 5 times, to obtain a graphene film covered on PMMA, immersed in deionized water, and then the graphene film covered on PMMA was lifted by another piece of Cu-based graphene, the surface moisture was blown dry by an air gun, heated on a hot plate at 100℃ for 8 min, immersed in a 2 mol / L ammonium persulfate solution for 30 min again, and then washed with deionized water for 5 times, to obtain a multilayer graphene film covered on PMMA, immersed in deionized water, and then lifted out by a glass sheet for standby.

[0043] A bundle of carbon nanotubes was grabbed at the edge of the carbon nanotube array by a clamp, and a precision manipulator was started to horizontally stretch at a speed of 1 mm / s to form a CNT net, the dry spinning device was used to directly deposit the stretched CNT net on the surface of the multilayer graphene film covered on PMMA, and the CNT net was deposited by cross-stacking for 2 times, then immersed in anhydrous ethanol for 30 min, taken out, and dried at room temperature, immersed in acetone for 4 h, to obtain a graphene-CNT composite net, immersed in deionized water, and then lifted by a polytetrafluoroethylene sheet, the graphene-CNT composite net was covered on the surface of a device substrate, placed in a hot press, and kept at 80℃ for 10 min under a pressure of 0.1 MPa, then cooled to room temperature, and the polytetrafluoroethylene sheet was peeled off, to obtain a substrate covered with graphene-CNT composite net.

[0044] In a nitrogen glove box, 2.8 g of PbI2 was added into 5 mL of mixed solvent (DMSO and DMF with a volume ratio of 1:4) and mixed uniformly, then 0.9 g of FAI, 0.11 g of CsI, 0.02 g of MABr, and 0.1 g of MACl were added, the container was sealed, placed on a magnetic stirrer, and stirred at a speed of 700 rpm for 15 h in the dark, 15 mg of urea and 1.5 mg of N-(3-dimethylaminopropyl) methacrylamide (DPM) were added for continued stirring in the dark for 5 h, the solution was sucked by a syringe and filtered through a 0.22 μm organic needle filter, to prepare a perovskite precursor solution.

[0045] After the substrate covered with graphene-CNT composite net was preheated on a hot plate at 100℃ for 1 min, 100 μL of perovskite precursor solution was added dropwise on the surface of graphene-CNT composite net, and then spin-coated at 1000 rpm for 10 s, followed by spin-coating at 4000 rpm for 20 s. 150 μL of anhydrous chlorobenzene was added dropwise, and then spin-coated at 4000 rpm for 20 s. After being kept at 100℃ for 15 min and then heated to 150℃ for 12 min, the sample was naturally cooled to room temperature to obtain a high-transparency perovskite battery film.

[0046] Example 2

[0047] After 0.5 mL of a 5% poly(methyl methacrylate) solution was added dropwise to the surface of Cu-based graphene and spin-coated at 1000 rpm for 20 s, the sample was baked on a hot plate at 150℃ for 2 min. After being immersed in 300 mL of a 0.5 mol / L iron chloride solution for 30 min and then washed with deionized water for 3 times, a graphene film covered with PMMA was obtained. The graphene film was immersed in deionized water, and then a piece of Cu-based graphene was used to fish out the graphene film covered with PMMA. After the surface moisture was blown dry with an air gun, the sample was heated on a hot plate at 80℃ for 5 min. After being immersed in a 0.5 mol / L iron chloride solution for 30 min and then washed with deionized water for 3 times, a multilayer graphene film covered with PMMA was obtained. The graphene film was immersed in deionized water and then fished out with a glass sheet for standby use.

[0048] At the edge of the carbon nanotube array, a bundle of carbon nanotubes was grabbed with a clamp, and a precision manipulator was started to horizontally stretch at a speed of 5 mm / s to form a CNT net. The stretched CNT net was directly deposited on the surface of the multilayer graphene film covered with PMMA by using a dry spinning device. After the CNT net was deposited twice by the cross-stacking method, the sample was immersed in anhydrous ethanol for 15 min, taken out, and then dried at room temperature. After being immersed in acetone for 2 h, a graphene-CNT composite net was obtained. After the graphene-CNT composite net was covered on the surface of a device substrate and then placed in a hot press at a pressure of 0.1 MPa and a temperature of 60℃ for 10 min, the sample was cooled to room temperature. After the polytetrafluoroethylene sheet was peeled off, a substrate covered with graphene-CNT composite net was obtained.

[0049] In a nitrogen glove box, 2.7 g of PbI2 was added to 5 mL of mixed solvent (DMSO and DMF in a volume ratio of 1:4) and mixed uniformly, then 0.8 g of FAI, 0.1 g of CsI, 0.02 g of MABr, and 0.07 g of MACl were added. The container was sealed and placed on a magnetic stirrer for 10 h at a speed of 500 rpm in the dark. Then 20 mg of urea and 1 mg of N-(3-dimethylaminopropyl) methacrylamide (DPM) were added and the stirring was continued for 4 h in the dark. The solution was drawn up using a syringe and filtered through a 0.22 μm organic needle filter to obtain a perovskite precursor solution.

[0050] After preheating the substrate covered with the graphene-CNT composite net on a hot plate at 100°C for 1 min, 80 μL of perovskite precursor solution was added dropwise onto the surface of the graphene-CNT composite net. After spin coating at 500 rpm for 10 s, spin coating was performed at 4000 rpm for 15 s. Then 120 μL of anhydrous chlorobenzene was added dropwise, and spin coating was performed at 4000 rpm for 10 s. The temperature was maintained at 100°C for 10 min, then increased to 150°C for 10 min, and then naturally cooled to room temperature to obtain a high-transparency perovskite battery thin film.

[0051] Example 3

[0052] After 1 mL of a 5% by mass solution of polymethyl methacrylate was added dropwise to the surface of the Cu-based graphene and spin coated at a speed of 1000 rpm for 20 s, the graphene was baked on a hot plate at 180°C for 5 min. The graphene was immersed in a 300 mL solution of iron chloride with a molar concentration of 2 mol / L for 60 min, then washed with deionized water 4 times to obtain a graphene film covered with PMMA. The graphene film was immersed in deionized water and then lifted out of the water using another piece of Cu-based graphene. After the surface moisture was blown dry with an air gun, the graphene was heated on a hot plate at 100°C for 10 min. The graphene was again immersed in a 300 mL solution of iron chloride with a molar concentration of 2 mol / L for 60 min, then washed with deionized water 4 times to obtain a multilayer graphene film covered with PMMA. The graphene film was immersed in deionized water and then lifted out of the water using a glass sheet for later use.

[0053] A bundle of carbon nanotubes is grabbed by a clamp at the edge of the carbon nanotube array, a precision manipulator is started to horizontally stretch at a speed of 2 mm / s to form a CNT network, a dry spinning device is used to directly deposit the stretched CNT network onto the surface of the multilayer graphene film covered on PMMA, after depositing the CNT network twice by the cross-stacking method, the sample is immersed in anhydrous ethanol for 20 min, taken out and dried at room temperature, immersed in acetone for 5 h to obtain a graphene-CNT composite network, immersed in deionized water, and then taken out by a polytetrafluoroethylene sheet, and the graphene-CNT composite network is covered on the surface of a device substrate, and then placed in a hot press at a pressure of 0.1 MPa and a temperature of 70℃ for 10 min, cooled to room temperature, and then the polytetrafluoroethylene sheet is peeled off to obtain a substrate covered with a graphene-CNT composite network.

[0054] In a nitrogen glove box, 3 g of PbI2 is added to 5 mL of mixed solvent (DMSO and DMF in a volume ratio of 1:4) and mixed uniformly, then 1 g of FAI, 0.15 g of CsI, 0.03 g of MABr, and 0.1 g of MACl are added, the container is sealed, placed on a magnetic stirrer, and stirred at a speed of 700 rpm in the dark for 15 h, then 15 mg of urea and 1.2 mg of N-(3-dimethylaminopropyl) methacrylamide (DPM) are added and continue to stir in the dark for 5 h, the solution is sucked using a syringe and filtered through a 0.22 μm organic needle filter to prepare a perovskite precursor solution.

[0055] The substrate covered with the graphene-CNT composite network is preheated on a hot stage at 100℃ for 1 min, then 100 μL of perovskite precursor solution is added dropwise on the surface of the graphene-CNT composite network, spin-coated at 1000 rpm for 10 s, then spin-coated at 4000 rpm for 20 s, 150 μL of anhydrous chlorobenzene is added dropwise, spin-coated at 4000 rpm for 20 s, then kept at 100℃ for 15 min, heated to 160℃ for 12 min, and naturally cooled to room temperature to prepare a high-transmittance perovskite battery film.

[0056] Example 4

[0057] 0.6 mL of a 5% by mass polymethyl methacrylate solution was added dropwise to the surface of Cu-based graphene, and spin-coated at a speed of 1000 rpm for 20 s, and then baked on a hot plate at 160°C for 4 min. After being immersed in 300 mL of a 1 mol / L ammonium persulfate solution for 50 min, the graphene film coated on the PMMA was rinsed with deionized water four times, immersed in deionized water, and then the graphene film coated on the PMMA was fished up with another piece of Cu-based graphene. After the surface moisture was blown dry with an air gun, the graphene film coated on the PMMA was heated on a hot plate at 90°C for 8 min, and then immersed in a 4 mol / L ammonium persulfate solution for 50 min. After being rinsed with deionized water four times, a multilayer graphene film coated on the PMMA was obtained, immersed in deionized water, and then fished out with a glass sheet for standby use.

[0058] At the edge of the carbon nanotube array, a bundle of carbon nanotubes was grabbed with a clamp, and a precision manipulator was started to stretch horizontally at a speed of 3 mm / s to form a CNT web. The dry spinning device was used to directly deposit the stretched CNT web onto the surface of the multilayer graphene film coated on the PMMA. After the CNT web was deposited twice in a cross-stacking manner, the graphene-CNT composite web was obtained by immersing in anhydrous ethanol for 18 min, taking out, and air-drying at room temperature, and then immersing in acetone for 3.5 h. After being immersed in deionized water and fished up with a polytetrafluoroethylene sheet, the graphene-CNT composite web was covered on the surface of a device substrate, and then placed in a hot press. After being kept at 75°C for 10 min under a pressure of 0.1 MPa, the graphene-CNT composite web was cooled to room temperature, and then the polytetrafluoroethylene sheet was peeled off to obtain a substrate covered with the graphene-CNT composite web.

[0059] In a nitrogen glove box, 2.9 g of PbI2 was added into 5 mL of a mixed solvent (DMSO and DMF in a volume ratio of 1:4) and mixed uniformly. Then, 0.9 g of FAI, 0.14 g of CsI, 0.025 g of MABr, and 0.09 g of MACl were added. The container was sealed and placed on a magnetic stirrer for stirring at a speed of 600 rpm for 12 h in the dark. Then, 17 mg of urea and 1.3 mg of N-(3-dimethylaminopropyl) methacrylamide (DPM) were added for further stirring in the dark for 4.5 h. The solution was drawn by a syringe and filtered through a 0.22 μm organic needle filter to prepare a perovskite precursor solution.

[0060] The substrate covered with graphene-CNT composite net was preheated on a hot plate at 100℃ for 1 min, then 90 μL of perovskite precursor solution was added on the surface of graphene-CNT composite net, and was spin-coated at 800 rpm for 10 s, then was spin-coated at 4000 rpm for 17 s, 130 μL of anhydrous chlorobenzene was added, and was spin-coated at 4000 rpm for 18 s, and was kept at 100℃ for 12 min, and was heated to 155℃ for 11 min, and was naturally cooled to room temperature, to obtain a high-transparency perovskite battery film.

[0061] Example 5

[0062] 0.7 mL of 5% poly(methyl methacrylate) solution was added to the Cu-based graphene surface, and was spin-coated at 1000 rpm for 20 s, and was baked on a hot plate at 170℃ for 2 min, and was immersed in 300 mL of 1 mol / L iron chloride solution for 40 min, and was washed with deionized water for 4 times, to obtain a graphene film covered on PMMA, and was immersed in deionized water, and was taken out with another piece of Cu-based graphene to cover the graphene film on PMMA, and was blown dry with an air gun, and was heated on a hot plate at 80℃ for 6 min, and was immersed in 1 mol / L iron chloride solution for 30 min, and was washed with deionized water for 3 times, to obtain a multilayer graphene film covered on PMMA, and was immersed in deionized water, and was taken out with a glass sheet for standby.

[0063] A bundle of carbon nanotubes was grabbed with a clamp at the edge of the carbon nanotube array, and a precision manipulator was started to horizontally stretch at a speed of 4 mm / s, to form a CNT net, and a dry spinning device was used to directly deposit the stretched CNT net on the surface of the multilayer graphene film covered on PMMA, and the CNT net was deposited by cross-stacking for 2 times, and was immersed in anhydrous ethanol for 20 min, and was taken out and dried at room temperature, and was immersed in acetone for 3 h, to obtain a graphene-CNT composite net, and was immersed in deionized water, and was taken out with a polytetrafluoroethylene sheet, and the graphene-CNT composite net was covered on the surface of a device substrate, and was placed in a hot press, and was kept at 70℃ for 10 min at a pressure of 0.1 MPa, and was cooled to room temperature, and the polytetrafluoroethylene sheet was peeled off, to obtain a substrate covered with graphene-CNT composite net.

[0064] In a nitrogen glove box, 2.7 g of PbI2 was added into 5 mL of mixed solvent (DMSO and DMF in a volume ratio of 1:4) and mixed uniformly, then 1 g of FAI, 0.1 g of CsI, 0.022 g of MABr, and 0.1 g of MACl were added, the container was sealed and placed on a magnetic stirrer, and stirred at a speed of 500 rpm in the dark for 10 h, then 15 mg of urea and 1.5 mg of N-(3-dimethylaminopropyl) methacrylamide (DPM) were added and continued to stir in the dark for 4 h, the solution was sucked using a syringe and filtered through a 0.22 μm organic needle filter to obtain a perovskite precursor solution.

[0065] After preheating the substrate covered with the graphene-CNT composite net on a hot stage at 100℃ for 1 min, 95 μL of perovskite precursor solution was added dropwise on the surface of the graphene-CNT composite net, and then spin-coated at 600 rpm for 10 s, followed by spin-coating at 4000 rpm for 15 s, 130 μL of anhydrous chlorobenzene was added dropwise, and then spin-coated at 4000 rpm for 15 s, and then kept at 100℃ for 12 min, and then heated to 160℃ for 12 min, and then naturally cooled to room temperature to obtain a high-transparency perovskite battery thin film.

[0066] The present application also carries out comparative examples and related tests.

[0067] Comparative Example 1

[0068] Compared with Example 1, the only difference is that N-(3-dimethylaminopropyl) methacrylamide is not added, and the other preparation methods and components are completely consistent, and finally a high-transparency perovskite battery thin film is obtained.

[0069] Comparative Example 2

[0070] Compared with Example 1, the only difference is that the graphene-CNT composite net is not prepared, and the other preparation methods and components are completely consistent, and finally a high-transparency perovskite battery thin film is obtained.

[0071] Comparative Example 3

[0072] Compared with Example 1, the difference is only that the multilayer graphene is prepared instead of graphene-CNT composite net, namely: 0.7 mL of 5% polymethyl methacrylate solution is dropped onto the surface of Cu-based graphene, and after spin coating at a speed of 1000 rpm for 20 s, baking on a hot plate at 150℃ for 5 min, immersing in 300 mL of 2 mol / L ammonium persulfate solution for 30 min, and then washing with deionized water for 5 times, a graphene film covered on PMMA is obtained, and then the graphene film is immersed in deionized water, and another piece of Cu-based graphene is used to lift the graphene film covered on PMMA, and after the surface moisture is blown dry with an air gun, the graphene film is heated on a hot plate at 100℃ for 8 min, and then immersed in 2 mol / L ammonium persulfate solution for 30 min, and then washed with deionized water for 5 times, a multilayer graphene film covered on PMMA is obtained, and then the multilayer graphene is immersed in deionized water and lifted with a piece of polytetrafluoroethylene, and then the multilayer graphene is covered on the surface of a device substrate, and then placed in a hot press, and then kept at 80℃ for 10 min under a pressure of 0.1 MPa, and then cooled to room temperature, and then the polytetrafluoroethylene is peeled off, and then a substrate covered with multilayer graphene is obtained; other preparation methods and components are completely consistent, and finally a high-transparency perovskite battery film is prepared.

[0073] Performance test

[0074] The high-transparency perovskite battery films prepared in Examples 1-5 and Comparative Examples 1-3 are subjected to performance test analysis, and the specific test analysis is as follows:

[0075] (1) The morphology of the film is analyzed by using an energy field emission scanning electron microscope (model JSM-7610F), and the scanning electron microscope image of the high-transparency perovskite battery film prepared in Comparative Example 1 is shown in Figure 1 , and the scanning electron microscope image of the high-transparency perovskite battery film prepared in Example 1 is shown in Figure 2 ;

[0076] (2) The photoluminescence characteristics of the high-transparency perovskite battery films prepared in Examples 1-5 and Comparative Examples 1-3 on the glass substrate are measured by using a Hitachi F-4600 spectrophotometer, and the photoluminescence spectrum is shown in Figure 3 ;

[0077] (3) The current-voltage (J-V) characteristics of the battery samples prepared by using the high-transparency perovskite battery films in Examples 1-5 and Comparative Examples 1-3 are tested by using an AM 1.5G standard solar simulator (light intensity 100 mW / cm 2 , model PT-SUN2S) and a test source table (model Keithley 2400), and the light illumination area is set to 0.051 cm 2During testing, the scan range was -0.2V to 1.2V, and the scan step size was 0.025V / s. The specific open-circuit voltage (V...) oc (V), short-circuit current density (J) sc mA / cm 2 The test results for fill factor (FF, %) and photoelectric conversion efficiency (PCE, %) are shown in Table 1.

[0078] (4) Electrochemical impedance spectroscopy

[0079] Electrochemical impedance spectroscopy (EIS) and charge transfer resistance (Rct, Ω·cm) were performed on the high-transmittance perovskite solar cell films prepared in Examples 1-5 and Comparative Examples 1-3 using an electrochemical workstation (model CHI760E) at a bias voltage of 0.8V. 2 The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] As shown in Table 1, the photoelectric conversion efficiency of the battery samples prepared using the high-transparency perovskite solar cell films of Examples 1-5 can all reach over 20%. The photoelectric conversion efficiency of Example 1 can reach 22.5%, where the open-circuit voltage V... oc 1.21V, short-circuit current density J sc 22.8 mA / cm 2 The fill factor was 81.5%, which was significantly better than that of comparative examples 1-3.

[0083] Based on the data in Table 1 and Figures 1-2 Analysis shows that, due to the absence of N-(3-dimethylaminopropyl)methacrylamide in Comparative Example 1, [the following is unclear and likely incomplete: "from..."] Figure 1 The scanning electron microscope (SEM) images clearly show that its planar morphology exhibits uneven grain structure, numerous fine particles, cracks at grain boundaries, poor flatness, and many pinholes. Figure 2 As shown in the scanning electron microscope image of Example 1, the addition of N-(3-dimethylaminopropyl)methacrylamide (DPM) resulted in a larger and more uniform grain size and a smoother surface in the final high-transmittance perovskite solar cell film. Furthermore, compared to Comparative Example 1, the addition of DPM in Example 1 significantly suppressed ion migration, leading to increased VT... oc Significantly improved. In Comparative Example 2, the charge transfer resistance increased significantly due to the absence of the graphene-CNT composite network, which also meant that its overall charge transport capability decreased significantly; in Comparative Example 3, the absence of the CNT network also resulted in a certain decrease in charge transport capability.

[0084] In addition, according to Figure 3As can be seen from the photoluminescence spectrum diagram shown in the middle, the addition of the graphene-CNT composite network in Example 1 shows higher fluorescence emission intensity, far exceeding Comparative Example 2. The increase in fluorescence intensity also indirectly indicates that the graphene-CNT composite network can have high light transmittance, so that the prepared high-transparency perovskite battery thin film has low carrier recombination rate, that is, the proportion of non-radiative recombination of photo-generated carriers in the thin film is reduced, the PL intensity is high, and energy loss can be effectively reduced

[0085] In summary, the graphene-CNT composite network in the high-transparency perovskite battery thin film prepared in Examples 1-5 of the present application improves the light transmittance by constructing a three-dimensional network, effectively converts incident visible light into electrical energy, improves the overall photoelectric conversion efficiency of the device, reduces the charge transfer resistance and improves the fill factor; and the DPM further passivates the grain boundary, cooperates with the graphene-CNT composite network to realize low recombination and high Voc, so that the overall photoelectric conversion efficiency of the device is better.

[0086] The above is the preferred embodiment of the present application, and those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a high-transparency perovskite battery thin film, characterized in that, It comprises the following steps: S1, the CNT network is deposited on the surface of the multilayer graphene film covered on PMMA, and then sequentially immersed in anhydrous ethanol and acetone, respectively, to obtain a graphene-CNT composite network immersed in deionized water, and then taken out with a polytetrafluoroethylene sheet to cover the surface of the device substrate, hot-pressed, cooled, and the polytetrafluoroethylene sheet is peeled off to obtain a substrate covered with a graphene-CNT composite network; S2, in a nitrogen glove box, PbI2, FAI, CsI, and MABr are added to a mixed solvent, sealed, stirred in the dark, N-(3-dimethylaminopropyl) methacrylamide is added and continues to be stirred, filtered, and a perovskite precursor solution is prepared; S3, the substrate covered with the graphene-CNT composite network is preheated, then the perovskite precursor solution and anhydrous chlorobenzene are sequentially added to the surface of the graphene-CNT composite network for spin coating, and then heated and cooled to room temperature to obtain a high-transparency perovskite battery film.

2. The method of claim 1, wherein the method is characterized by: The multilayer graphene film covered on PMMA is prepared by adding a 5% poly(methyl methacrylate) solution to the surface of Cu-based graphene, spin coating at a speed of 1000 rpm for 20 s, baking on a hot plate at 150-180℃ for 2-5 min, immersing in a copper etching solution with a molar concentration of 0.5-2 mol / L for 30-60 min, rinsing with deionized water for 3-5 times, immersing in deionized water again, taking out the graphene film covered on PMMA with another Cu-based graphene, blowing dry the surface moisture, heating at 80-100℃ for 5-10 min, immersing in the copper etching solution with a molar concentration of 0.5-2 mol / L for 30-60 min, and rinsing with deionized water for 3-5 times to obtain a multilayer graphene film covered on PMMA.

3. The method of claim 2, wherein the method further comprises the step of: The Cu-based graphene is prepared by placing a copper foil substrate in a tube furnace, maintaining an argon atmosphere, heating the furnace to 1030℃, introducing hydrogen for 20 min, maintaining the temperature and hydrogen flow, introducing methane gas at a pressure of 9 Torr for 10 min, turning off the methane gas, maintaining the hydrogen and argon atmosphere, rapidly cooling to below 500℃, turning off the hydrogen and only maintaining the argon gas flow when the temperature drops to 200℃, and cooling to room temperature. ​ 4. The method of claim 3, wherein the method further comprises the step of: The flow rate of argon is 100 sccm, the flow rate of hydrogen is 50 sccm, and the flow rate of methane gas is 7 sccm. ​ 5. The method of claim 1, wherein the method further comprises the step of: The CNT network is obtained by grabbing a bundle of carbon nanotubes at the edge of a carbon nanotube array with a clamp, starting a precision manipulator, and horizontally stretching at a speed of 1-5 mm / s. ​ The carbon nanotube array is prepared by placing a SiO2 / Si substrate with deposited FeCl2 catalyst in a tube furnace, maintaining an argon atmosphere with a flow rate of 100 sccm, heating the furnace to 800℃, introducing acetylene gas with a flow rate of 10 sccm at a pressure of 9 Torr for 15 min, turning off the acetylene gas, maintaining the argon atmosphere, and cooling to room temperature.

6. The method of claim 1, wherein the method further comprises the step of: In the step S1, the CNT network is directly deposited onto the surface of the multi-layer graphene film coated on the PMMA using a dry spinning device, the CNT network is deposited twice by cross-stacking, immersed in anhydrous ethanol for 15-30 min, taken out and dried at room temperature, immersed in acetone for 2-5 h to obtain a graphene-CNT composite network, immersed in deionized water, and the graphene-CNT composite network is covered on the surface of a device substrate and placed in a hot press at a pressure of 0.1 MPa for 10 min at 60-80℃, cooled to room temperature, and the polytetrafluoroethylene sheet is peeled off to obtain a substrate covered with a graphene-CNT composite network. ​ 7. The method of claim 1, wherein the method further comprises the step of: In the step S2, MACl is added when PbI2, FAI, CsI and MABr are added, and urea is added when N-(3-dimethylaminopropyl) methacrylamide is added. ​ 8. The method of claim 7, wherein the method further comprises the step of: In the step S2, in the nitrogen glove box, 2.7-3 parts of PbI2 are added into a mixed solvent and mixed uniformly, then 0.8-1 parts of FAI, 0.1-0.15 parts of CsI, 0.02-0.03 parts of MABr and 0.07-0.1 parts of MACl are added, sealed, stirred at a speed of 500-700 rpm in the dark for 10-15 h, 0.015-0.02 parts of urea and 0.001-0.0015 parts of N-(3-dimethylaminopropyl) methacrylamide are added and continue to stir in the dark for 4-5 h, the solution is sucked using a syringe, filtered, and a perovskite precursor solution is prepared; the mixed solvent is DMSO and DMF, and the volume ratio of DMSO to DMF is 1:

4. ​ 9. The method of claim 1, wherein the method further comprises the step of: In the step S3, the substrate covered with the graphene-CNT composite network is preheated on a hot stage at 100℃ for 1 min, 80-100 parts by volume of the perovskite precursor solution is added dropwise onto the surface of the graphene-CNT composite network, spin-coated at a speed of 500-1000 rpm for 10 s, then spin-coated at a speed of 4000 rpm for 15-20 s, 120-150 parts by volume of anhydrous chlorobenzene is added dropwise, spin-coated at a speed of 4000 rpm for 10-20 s, kept at 100℃ for 10-15 min, heated to 150-160℃ for 10-12 min, and naturally cooled to room temperature to obtain a high-transparency perovskite battery film. ​ 10. A high transparent perovskite cell thin film, characterized in that, The preparation method is prepared by using any one of claims 1-9.

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