Guanidinooxalic acid additive modified perovskite thin film and preparation method and application thereof

Abstract

The invention discloses a guanidino oxalic acid additive modified perovskite thin film and a preparation method and application thereof. The perovskite thin film comprises a guanidino oxalic acid additive. The chemical and physical microenvironment of the perovskite thin film is regulated and controlled through guanidino oxalic acid molecules, guanidino functional groups are tightly combined with a perovskite inorganic framework through hydrogen bonds, carboxyl functional groups are coordinated with inorganic metal in the perovskite thin film through electrostatic interaction, the interaction between a solvent and a perovskite material is effectively weakened through the combined action of the guanidino functional groups and the inorganic metal, and the perovskite thin film is prepared. Delta-alpha phase conversion in the initial growth process of perovskite is promoted, and residues of a high-boiling-point solvent in the perovskite thin film are reduced; meanwhile, vacancy defects caused by volatilization of organic components in the perovskite annealing process can also be repaired, so that the perovskite thin film with high crystallinity and low defect density is realized, and the photoelectric conversion efficiency and the stability of the perovskite solar cell are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cells, and specifically relates to a perovskite film modified by a guanidino oxalic acid additive, a preparation method thereof, and an application thereof; more specifically, relates to a perovskite film modified by a guanidino oxalic acid additive, a preparation method thereof, and an application thereof in a perovskite solar cell. Background Art

[0002] In recent years, halide perovskite solar cells have made rapid progress due to their light weight, high weak light response efficiency and solution processing. They have achieved 26.95% (0.0583cm 2 ) and 22.46% (715.1cm 2 ) certified photoelectric conversion efficiency. However, the uncontrollable δ-α phase transition dynamics and volatile component loss of the perovskite film during the annealing process will lead to various types of impurities and defects in perovskite solar cells, such as δ-phase perovskite, Pb 0 , gap or vacancy defects, etc.; at the same time, when the area of ​​the perovskite device is enlarged, the decrease in film uniformity will lead to current mismatch and voltage load imbalance. These problems become the main obstacles to the module's photoelectric conversion efficiency and repeatability, and will further affect the device's operating stability.

[0003] At present, by replacing solvents with strong coordination or introducing additives, the perovskite crystallization kinetics can be regulated, the solvent evaporation rate can be accelerated, and the passivation uniformity can be improved. However, on the one hand, the solvent replacement strategy fails to solve the problem of film defects; on the other hand, the passivation additives are bonded to the perovskite material through a single hydrogen bond, ionic bond or π-π interaction, and cannot achieve a long-lasting and stable passivation ability, resulting in device efficiency and stability issues becoming a bottleneck for its commercial application. Summary of the invention

[0004] In order to improve the existing technical problems, the present invention provides a perovskite film modified by a guanidino oxalic acid additive and a perovskite solar cell prepared by using the same. The film uses a guanidino oxalic acid additive to adjust the components of a perovskite precursor solution to form a perovskite film modified by a guanidino oxalic acid additive. The guanidino oxalic acid molecules form hydrogen bonds and electrostatic bonding with the perovskite material through amino and carboxylate functional groups, promoting the δ-α phase conversion of the initial growth dynamics of the perovskite; at the same time, the strong interaction between the two can weaken the interaction between the solvent and the perovskite material and reduce the solvent residue; in addition, the guanidino oxalic acid molecules have a strong adsorption effect on the perovskite material, which can reduce the defects caused by the volatilization of organic components during the annealing process, effectively stabilize the perovskite components, and further form a perovskite film with a smooth surface, high crystallinity, and low defect state density.

[0005] The embodiment adopted in the present invention is:

[0006] A perovskite film comprising a guanidino oxalic acid additive.

[0007] According to an embodiment of the present invention, the perovskite film further comprises ABX 3 Perovskite materials composed of a perovskite lattice, where A is CH 3 NH 3 + (MA), HC(NH 2 ) 2 + (FA), Cs + and Rb + One or more of the following; B is Pb 2+ Sn 2+ At least one of - Br - , Cl - At least one of .

[0008] According to an embodiment of the present invention, the guanidino oxalic acid molecule forms hydrogen bonds and electrostatic bonding with the perovskite material through the amino and carboxylate functional groups.

[0009] According to an embodiment of the present invention, guanidino oxalic acid molecules have a strong adsorption effect on the perovskite material.

[0010] According to an embodiment of the present invention, the perovskite film is prepared by mixing a perovskite precursor solution and a guanidino oxalic acid additive.

[0011] According to an embodiment of the present invention, the preparation of the perovskite precursor solution adopts a technique known in the art. For example, the preparation method of the perovskite precursor solution is:

[0012] The A-containing halide and the B-containing halide are mixed in an organic solvent to obtain the perovskite precursor solution.

[0013] According to an embodiment of the present invention, the A-containing halide includes one or more of FAX, MAX, RbX and CsX, such as FAI (formamidine hydroiodide), MACl (methylamine hydrochloride), RbCl or CsCl.

[0014] According to an embodiment of the present invention, the B-containing halide comprises PbX 2 SnX 2 At least one of, for example, PbI 2 SnI 2 .

[0015] According to an embodiment of the present invention, the organic solvent is selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetonitrile (ACN) and 2-methoxyethanol (2-Me).

[0016] Preferably, the concentration of the perovskite precursor solution is 1.0-2.0M, for example, 1.8M.

[0017] According to an embodiment of the present invention, the mixing temperature is 25-70°C, preferably 35-50°C; the mixing time is 1-8h, preferably 3-6h.

[0018] According to an embodiment of the present invention, the molar content of the guanidine oxalic acid additive is 0.30-0.75 mol% of the perovskite precursor solution, for example, 0.30 mol%, 0.40 mol%, 0.45 mol%, 0.50 mol%, 0.60 mol%, 0.70 mol% or 0.75 mol%.

[0019] According to an embodiment of the present invention, the thickness of the perovskite film is 300-1000 nm, preferably 400-800 nm, and more preferably 400-600 nm.

[0020] According to an embodiment of the present invention, the preparation method of the guanidino oxalic acid additive comprises the following steps:

[0021] The additive is obtained by mixing guanidine acetate and oxalic acid in an organic solvent.

[0022] According to an embodiment of the present invention, the molar ratio of guanidine acetate to oxalic acid is 1-5:1, preferably 1-3:1, for example 2:1.

[0023] Preferably, in the preparation of the guanidino oxalic acid additive, the mixing temperature is, for example, room temperature; and the mixing time is 1-8 hours, preferably 2-6 hours.

[0024] Preferably, the organic solvent is ethanol. The content of the organic solvent is not particularly limited in the present invention, as long as it can dissolve the raw materials.

[0025] Preferably, the preparation of the guanidino oxalic acid additive further includes post-treatment of the prepared product such as solvent removal, washing, and drying.

[0026] Specifically, the preparation method of the guanidino oxalic acid additive is:

[0027] Guanidine acetate and oxalic acid were dissolved in ethanol, stirred at room temperature for 4 hours, and the solvent was distilled off. The obtained product was washed with anhydrous ethanol and then dried in a vacuum oven at 50° C. for 10 hours to obtain the additive.

[0028] The present invention also provides a method for preparing the above-mentioned perovskite film, the method comprising:

[0029] (1) preparing a perovskite precursor solution;

[0030] (2) mixing the perovskite precursor solution with the guanidino oxalic acid additive to obtain a mixed solution;

[0031] (3) Placing the mixed solution on a substrate and subjecting it to annealing treatment to obtain the perovskite film.

[0032] According to an embodiment of the present invention, the step of treating the substrate is further included before step (1): the substrate is ultrasonically cleaned in water, acetone, ethanol and isopropanol for 20 minutes respectively, and then placed in a UV ozone machine for treatment for 30 minutes.

[0033] According to an embodiment of the present invention, in step (2), the guanidine oxalic acid additive can be first dissolved in an organic solvent, and the organic solvent is one of DMF, DMSO, NMP, 2-Me, ethanol, chlorobenzene and methanol, preferably DMSO; the concentration of the additive is 0.30-0.75 mol% of the concentration of the perovskite precursor solution, preferably 0.30 mol%, 0.40 mol%, 0.45 mol%, 0.50 mol%, 0.60 mol%, 0.70 mol% or 0.75 mol%.

[0034] According to an embodiment of the present invention, in step (2), the concentration of the mixed solution is 1.0-2.0M, for example, 1.1-1.8M.

[0035] According to an embodiment of the present invention, in step (3), the substrate includes but is not limited to a silicon wafer, a quartz wafer, a glass wafer, a high molecular polymer substrate (PET), an indium tin oxide conductive glass (ITO), a fluorine-doped tin oxide conductive glass (FTO), a graphene substrate, a mica sheet, and a metal substrate.

[0036] According to an embodiment of the present invention, in step (3), placing the mixed solution on a substrate to form a perovskite film comprises the following steps: placing the mixed solution on a substrate by spin coating, scraping or slit coating, and annealing to form a perovskite film, for example, spin coating the mixed solution on a substrate, and annealing to form a perovskite film.

[0037] According to an embodiment of the present invention, in step (3), the annealing temperature is 100-150°C, and more preferably, the annealing temperature is 120-130°C.

[0038] According to an embodiment of the present invention, in step (3), the annealing time is 15-80 min, and more preferably, the annealing time is 40-60 min.

[0039] The present invention also provides an application of the perovskite film in the photovoltaic field.

[0040] Preferably, the perovskite film is used in a perovskite solar cell.

[0041] A perovskite solar cell comprises the perovskite film.

[0042] According to an embodiment of the present invention, the structure of the solar cell is sequentially a conductive substrate, an electron transport layer, the above perovskite film, a passivation layer, a hole transport layer and a metal electrode.

[0043] According to an embodiment of the present invention, the conductive substrate is one or more of FTO, ITO, and PET.

[0044] According to an embodiment of the present invention, the electron transport layer is an n-type inorganic or organic semiconductor material.

[0045] Preferably, the electron transport layer is an n-type inorganic semiconductor material selected from SnO 2 、TiO 2 , mesoporous TiO 2 / TiO 2 、TiO 2 / SnO 2 At least one of; Preferably, the electron transport layer is SnO 2 or TiO 2 One of the above, for example SnO 2 .

[0046] According to an embodiment of the present invention, the thickness of the electron transport layer is 10-120 nm, preferably the thickness of the electron transport layer is 30-100 nm, and further preferably, the thickness of the electron transport layer is 50-80 nm.

[0047] According to an embodiment of the present invention, the passivation layer is at least one of PEAI, HABr, OAI, MeO-PEAI or i-BABr.

[0048] According to an embodiment of the present invention, the hole transport layer comprises a hole transport material, for example, a p-type inorganic or organic semiconductor material.

[0049] Preferably, the hole transport material is Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), P3HT (polymer of 3-hexylthiophene), CuSCN or NiO x At least one of; preferably, the hole transport layer is one of Spiro-OMeTAD, PTAA or P3HT, for example, Spiro-OMeTAD.

[0050] According to an embodiment of the present invention, the hole transport layer further comprises an additive, and preferably the additive is at least one of tert-butylpyridine (tBP), Li salt (LiTFSI) and Co salt (FK209).

[0051] According to an embodiment of the present invention, the metal electrode is one of ITO, Ag, Au, Cu or C.

[0052] According to an embodiment of the present invention, the thickness of the metal electrode is 30-200 nm, preferably the thickness of the metal electrode is 50-150 nm, and further preferably, the thickness of the metal electrode is 80-100 nm.

[0053] The present invention also provides a method for preparing the above-mentioned perovskite solar cell, the method comprising:

[0054] An electron transport layer, the perovskite film, a passivation layer, a hole transport layer and a metal electrode are sequentially deposited on a conductive substrate.

[0055] According to an embodiment of the present invention, the method for preparing a solar cell comprises the following steps:

[0056] (S1) preparing a perovskite precursor solution, and mixing the perovskite precursor solution with a guanidino oxalic acid additive to obtain a mixed solution;

[0057] (S2) preparing an electron transport layer on a conductive substrate and performing annealing;

[0058] (S3) coating the mixed solution on the electron transport layer and heating and annealing to form the perovskite film;

[0059] (S4) preparing a passivation layer on the perovskite film;

[0060] (S5) preparing a hole transport layer on the passivation layer;

[0061] (S6) Depositing a metal electrode onto the hole transport layer to obtain a perovskite solar cell.

[0062] According to an embodiment of the present invention, in step (S2), the conductive substrate is FTO or ITO. Preferably, before preparing the electron transport layer on the conductive substrate, the conductive substrate can also be pretreated, specifically, the conductive substrate is ultrasonically cleaned for 20 minutes with a cleaning solution, water, acetone, ethanol and isopropanol, respectively, and after drying the solvent, it is treated with an ultraviolet ozone machine for 30 minutes or plasma for 10 minutes to increase the hydrophilicity of the conductive substrate.

[0063] According to an embodiment of the present invention, in step (S2), the electron transport layer preparation method includes spin coating, sol-gel method or chemical bath deposition method; preferably, the preparation method is spin coating.

[0064] According to an embodiment of the present invention, in step (S2), the annealing temperature is 130-190° C., preferably 150-180° C.; the annealing time is 10-60 min, preferably 20-40 min; and the annealing is performed in an environment with a humidity of about 30%.

[0065] According to an embodiment of the present invention, in step (S3), the preparation method of the perovskite film is selected from one of spin coating, blade coating or slit coating.

[0066] According to an embodiment of the present invention, in step (S4), the method for depositing a passivation layer on the perovskite film is: mixing a passivation agent with an organic solvent, and coating the obtained mixture on the perovskite film to obtain the passivation layer.

[0067] Preferably, the passivation agent is selected from at least one of PEAI, HABr, OAI, MeO-PEAI or i-BABr. Preferably, the coating method is one of spin coating, blade coating or slit coating. Preferably, the concentration of the passivation agent in the organic solvent is 1-4 mg / mL; preferably, the organic solvent is selected from at least one of isopropanol, chlorobenzene, chloroform, DMF, DMSO, etc.

[0068] According to an embodiment of the present invention, in step (S4), the hole transport layer can be prepared by a method known in the art, for example, the hole transport layer can be prepared by a method selected from spin coating, blade coating, slit coating or evaporation.

[0069] According to an embodiment of the present invention, in step (S6), the electrode is prepared by a method selected from evaporation, scraping or sputtering.

[0070] Preferably, in step (S2), a P1 track is provided on the conductive substrate, for example, the P1 track is formed by laser scribing.

[0071] Preferably, after step (S5), a P2 track is provided on the hole transport layer, for example, by laser scribing.

[0072] Preferably, after step (S6), a P3 track is provided on the electrode, for example, by laser scribing to form the P3 track; preferably, a P4 track is further scribed by laser,

[0073] The present invention also provides a perovskite photovoltaic module, which includes the above-mentioned perovskite solar cell.

[0074] According to an embodiment of the present invention, the photovoltaic module includes a plurality of the above-mentioned perovskite solar cells, and the plurality of the perovskite solar cells are connected in series.

[0075] For example, the module also includes connecting a plurality of the perovskite solar cells in series by laser scribing P1, P2, P3, and P4 to obtain the perovskite photovoltaic module.

[0076] The present invention also provides a method for preparing the above-mentioned perovskite photovoltaic module, comprising the following steps: assembling the perovskite solar cells to form the perovskite photovoltaic module.

[0077] Beneficial effects of the present invention

[0078] The invention provides a perovskite film, which comprises a guanidino oxalic acid additive. The guanidino oxalic acid molecules form hydrogen bonds and electrostatic bonding with the perovskite material through amino and carboxylate functional groups, thereby promoting the δ-α phase conversion of the initial growth dynamics of the perovskite. Meanwhile, the strong interaction between the two can weaken the interaction between the solvent and the perovskite material, thereby reducing the solvent residue. In addition, the guanidino oxalic acid molecules have a strong adsorption effect on the perovskite material, thereby reducing the defects caused by the volatilization of organic components during the annealing process, effectively stabilizing the perovskite components, and further forming a perovskite film with a smooth surface, high crystallinity, and low defect state density.

[0079] The present invention provides a method for preparing a perovskite film, which uses guanidino oxalic acid molecules as additives to prepare a perovskite precursor solution, and prepares a high-quality perovskite film by regulating the crystallization kinetics of the perovskite intermediate phase, in-situ repairing defects caused by component volatilization, and reducing high-boiling point solvent residues. This modification method is easy to operate, has good repeatability, and is suitable for large-scale industrial production.

[0080] The perovskite film of the present invention effectively improves the photoelectric conversion efficiency and stability of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is an in-situ GIWAXS comparison diagram of the unmodified perovskite film of Comparative Example 1 and the perovskite film modified with guanidino oxalic acid molecules in Example 1;

[0082] Figure 2This is a comparison diagram of in-situ fluorescence test of the unmodified perovskite film in comparative example 1 and the perovskite film modified with guanidino oxalic acid molecules in example 1;

[0083] Figure 3 This is a comparison chart of the residual solvent (DMSO) content of the unmodified perovskite film of Comparative Example 1 and the perovskite film modified with guanidino oxalic acid molecules in Example 1 at different annealing times;

[0084] Figure 4 Pseudo-color images (80-240K) and Arrhenius fitting results of the temperature-dependent fluorescence spectra of the unmodified perovskite film of Comparative Example 1 and the perovskite film modified with guanidino oxalic acid molecules in Example 1 at different temperatures (80-240K);

[0085] Figure 5 This is a comparison chart of the photoelectric conversion efficiency of a solar cell prepared from an unmodified perovskite film in Comparative Example 1 and a solar cell prepared from a perovskite film modified with guanidino oxalic acid molecules in Example 1;

[0086] Figure 6 This is a comparison chart of the photoelectric conversion efficiency of a photovoltaic module prepared from an unmodified perovskite film in Comparative Example 2 and a photovoltaic module prepared from a perovskite film modified with guanidino oxalic acid molecules in Example 8;

[0087] Figure 7 This is a stability test comparison chart of the solar cell prepared with the unmodified perovskite film in Comparative Example 1 and the solar cell prepared with the perovskite film modified with the guanidino oxalic acid molecules in Example 1. DETAILED DESCRIPTION

[0088] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0089] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0090] Preparation Example 1

[0091] 0.04 mol of guanidine acetate and 0.02 mol of oxalic acid were dissolved in 40 mL of ethanol, stirred at room temperature for 4 h, and the solvent was distilled off. The obtained product was washed with anhydrous ethanol and then dried in a vacuum oven at 50° C. for 10 h to obtain a guanidine oxalic acid additive.

[0092] Example 1

[0093] The preparation method of perovskite solar cells is:

[0094] (1) Preparation of perovskite precursor solution and mixed solution: weigh FAI and PbI with a molar ratio of 1:1:0.35. 2 , MACl, dissolved in DMF / DMSO mixed solvent, and heated to 40 ℃ under N 2 The mixture was stirred in an atmosphere for 4 hours to completely dissolve the mixture, and the obtained perovskite precursor solution was mixed with the guanidino oxalic acid additive in Preparation Example 1 to obtain a 1.8 M mixed solution, wherein the concentration of the guanidino oxalic acid additive was 0.60 mol% of the concentration of the precursor solution.

[0095] (2) Pretreatment of FTO conductive glass: The FTO conductive substrate was ultrasonically cleaned in cleaning solution, deionized water, acetone, ethanol and isopropanol for 20 minutes in sequence, and then the solvent was removed with nitrogen gas. The substrate was placed in a UV ozone machine for 30 minutes and set aside.

[0096] (3) Preparation of electron transport layer: SnO 2 The colloid (15 wt%) was diluted to 2.67 wt% with deionized water and spin-coated onto the FTO substrate at a speed of 3000 rpm / s, followed by annealing at 150 °C for 30 min in an atmosphere with a humidity of ∼30% to obtain FTO / SnO 2 Base.

[0097] (4) Preparation of perovskite film: The prepared mixed solution containing perovskite precursor solution and additives is deposited on FTO / SnO by spin coating. 2 The spin coating speed was 5000 rpm / s, and the intermediate phase perovskite film was heated at 120 °C for 60 min to obtain the cubic phase FAPbI 3 Perovskite film, the annealed perovskite film is cooled to room temperature for use.

[0098] (5) Preparation of passivation layer: A 2 mg / mL i-BABr isopropanol solution was prepared and deposited on the perovskite film by spin coating. The rotation speed was controlled at 5000 rpm / s and the spin coating time was 30 s to form a passivation layer.

[0099] (6) Preparation of hole transport layer: A hole transport layer solution (90 mg Spiro-OMeTAD, 35.5 μL tBP, 23 μL LiTFSI, 15 μL FK209 dissolved in 1 mL chlorobenzene) was deposited onto the surface of the above film by spin coating. The rotation speed was controlled at 5000 rpm / s and the spin coating time was 30 s to form a hole transport layer.

[0100] (7) Preparation of metal electrodes: Electrodes with a thickness of 80-100 nm were deposited by thermal evaporation.

[0101] Among them, steps (2) and (3) are carried out in air, and the rest are completed in a glove box.

[0102] Example 2

[0103] The difference between Example 2 and Example 1 is that the concentration of the guanidine oxalic acid additive in step (1) is 0.30 mol % of the concentration of the precursor solution.

[0104] Example 3

[0105] The difference between Example 3 and Example 1 is that the concentration of the guanidine oxalic acid additive in step (1) is 0.45 mol % of the concentration of the precursor solution.

[0106] Example 4

[0107] The difference between Example 4 and Example 1 is that the concentration of the guanidine oxalic acid additive in step (1) is 0.75 mol % of the concentration of the precursor solution.

[0108] Example 5

[0109] The difference between Example 5 and Example 1 is that in step (1), CsI, FAI, and PbI in a molar ratio of 0.05:0.95:1:0.35 are weighed. 2 , MACl prepare perovskite precursor solution.

[0110] Example 6

[0111] (1) Preparation of perovskite precursor solution and mixed solution: Weigh CsI, FAI, PbI with a molar ratio of 0.05:0.95:1:0.35. 2 , MACl, dissolved in DMF / DMSO mixed solvent, and heated to 40 ℃ under N 2 The mixture was stirred in an atmosphere for 4 hours to completely dissolve the mixture, and the obtained perovskite precursor solution was mixed with the guanidino oxalic acid additive in Preparation Example 1 to obtain a 1.1 M mixed solution, wherein the concentration of the guanidino oxalic acid additive was 0.60 mol% of the concentration of the precursor solution.

[0112] (2) FTO conductive glass pretreatment: The FTO conductive glass was etched using a laser to form a P1 path; the etched glass substrate was ultrasonically cleaned in a cleaning solution, deionized water, acetone, ethanol, and isopropanol for 20 min, and then the solvent was removed with nitrogen. The substrate was placed in a UV ozone machine for 30 min and set aside.

[0113] (3) Preparation of electron transport layer: SnO 2 The colloid (15 wt%) was diluted to 2.67 wt% with deionized water and spin-coated onto the FTO substrate at a speed of 3000 rpm / s, followed by annealing at 150 °C for 30 min in an atmosphere with a humidity of ∼30% to obtain FTO / SnO 2Base.

[0114] (4) Preparation of perovskite film: The prepared mixed solution is deposited on FTO / SnO by blade coating. 2 On the substrate, the scraping speed is 5mm s -1 The slit width was 150 μm, and then the film was placed in a 10 Pa environment for 60 s to assist the evaporation of the high boiling point solvent. The obtained intermediate phase perovskite film was heated at 130 ° C for 20 min to obtain the cubic phase FAPbI 3 Perovskite film, the annealed perovskite film is cooled to room temperature for use.

[0115] (5) Preparation of passivation layer: A 2 mg / mL i-BABr isopropanol solution was prepared and deposited on the perovskite film by spin coating. The rotation speed was controlled at 5000 rpm / s and the spin coating time was 30 s to form a passivation layer.

[0116] (6) Preparation of hole transport layer: A hole transport layer solution (90 mg Spiro-OMeTAD, 35.5 μL tBP, 23 μL LiTFSI, 15 μL FK209 dissolved in 1 mL chlorobenzene) was deposited onto the surface of the above film by spin coating. The rotation speed was controlled to 5000 rpm / s and the spin coating time was 30 s to form a hole transport layer. Subsequently, a P2 track was scribed using a laser.

[0117] (7) Preparation of metal electrodes: 80-100 nm thick electrodes were deposited by thermal evaporation, followed by laser scribing of P3 and P4 tracks;

[0118] Among them, steps (1) and (7) are completed in a glove box, and the remaining layers are carried out in air.

[0119] Example 7

[0120] (1) Preparation of perovskite precursor solution and mixed solution: Weigh CsI, FAI, PbI with a molar ratio of 0.05:0.95:1:0.35. 2 , MACl, dissolved in DMF / NMP mixed solvent, 2 The mixture was stirred in an atmosphere for 4 hours to completely dissolve the mixture, and the obtained perovskite precursor solution was mixed with the guanidino oxalic acid additive in Preparation Example 1 to obtain a 1.1 M mixed solution, wherein the concentration of the guanidino oxalic acid additive was 0.60 mol% of the concentration of the precursor solution.

[0121] (2) FTO conductive glass pretreatment: The FTO conductive glass was etched using a laser to form a P1 path; the etched glass substrate was ultrasonically cleaned in a cleaning solution, deionized water, acetone, ethanol, and isopropanol for 20 min, and then the solvent was removed with nitrogen. The substrate was placed in a UV ozone machine for 30 min and set aside.

[0122] (3) Preparation of electron transport layer: SnO 2 The colloid (15 wt%) was diluted to 2.67 wt% with deionized water and spin-coated onto the FTO substrate at a speed of 3000 rpm / s, followed by annealing at 150 °C for 30 min in an atmosphere with a humidity of ∼30% to obtain FTO / SnO 2 Base.

[0123] (4) Preparation of perovskite thin film layer: The prepared mixed solution is deposited on FTO / SnO by doctor blade coating. 2 On the substrate, the scraping speed is 8mm s -1 , the slit width is 100 μm, and then the film is placed in a 10 Pa environment for 60 s to assist the evaporation of the high boiling point solvent. The obtained intermediate phase perovskite film is heated at 130 ° C for 30 min to obtain the cubic phase FAPbI 3 Perovskite film, the annealed perovskite film is cooled to room temperature for use.

[0124] (5) Preparation of passivation layer: A 2 mg / mL i-BABr isopropanol solution was prepared and deposited on the perovskite film by spin coating. The rotation speed was controlled at 5000 rpm / s and the spin coating time was 30 s to form a passivation layer.

[0125] (6) Preparation of hole transport layer: A hole transport layer solution (90 mg Spiro-OMeTAD, 35.5 μL tBP, 23 μL LiTFSI, 15 μL FK209 dissolved in 1 mL chlorobenzene) was deposited onto the surface of the above film by spin coating. The rotation speed was controlled to 5000 rpm / s and the spin coating time was 30 s to form a hole transport layer. Subsequently, a P2 track was scribed using a laser.

[0126] (7) Preparation of metal electrodes: 80-100 nm thick electrodes were deposited by thermal evaporation, followed by laser scribing of P3 and P4 tracks;

[0127] Among them, steps (1) and (7) are completed in a glove box, and the remaining layers are carried out in air.

[0128] Example 8

[0129] (1) Preparation of perovskite precursor solution and mixed solution: Weigh CsI, FAI, PbI with a molar ratio of 0.05:0.95:1:0.35. 2 , MACl, dissolved in 2-Me / DMSO mixed solvent, and heated to 40 ℃ under N 2 The mixture was stirred in an atmosphere for 4 hours to completely dissolve the mixture, and the obtained perovskite precursor solution was mixed with the guanidino oxalic acid additive in Preparation Example 1 to obtain a 1 M mixed solution, wherein the concentration of the guanidino oxalic acid additive was 0.60% of the concentration of the precursor solution.

[0130] (2) FTO conductive glass pretreatment: The FTO conductive glass was etched using a laser to form a P1 path; the etched glass substrate was ultrasonically cleaned in a cleaning solution, deionized water, acetone, ethanol, and isopropanol for 20 min, and then the solvent was removed with nitrogen. The substrate was placed in a UV ozone machine for 30 min and set aside.

[0131] (3) Preparation of electron transport layer: SnO 2 The colloid (15 wt%) was diluted to 2.67 wt% with deionized water and spin-coated onto the FTO substrate at a speed of 3000 rpm / s, followed by annealing at 150 °C for 30 min in an atmosphere with a humidity of ∼30% to obtain FTO / SnO 2 Base.

[0132] (4) Preparation of perovskite film: The prepared mixed solution is deposited on FTO / SnO by blade coating. 2 On the substrate, the scraping speed is 20mm s -1 , the slit width is 300 μm, and the intermediate phase perovskite film is heated at 130 °C for 20 min to obtain the cubic phase FAPbI 3 Perovskite film, the annealed perovskite film is cooled to room temperature for use.

[0133] (5) Preparation of passivation layer: A 2 mg / mL i-BABr isopropanol solution was prepared and deposited on the perovskite film by spin coating. The rotation speed was controlled at 5000 rpm / s and the spin coating time was 30 s to form a passivation layer.

[0134] (6) Preparation of hole transport layer: A hole transport layer solution (90 mg Spiro-OMeTAD, 35.5 μL tBP, 23 μL LiTFSI, 15 μL FK209 dissolved in 1 mL chlorobenzene) was deposited onto the surface of the above film by spin coating. The rotation speed was controlled to 5000 rpm / s and the spin coating time was 30 s to form a hole transport layer. Subsequently, a P2 track was scribed using a laser.

[0135] (7) Preparation of metal electrodes: 80-100 nm thick electrodes were deposited by thermal evaporation, followed by laser scribing of P3 and P4 tracks;

[0136] Among them, steps (1) and (7) are completed in a glove box, and the remaining layers are carried out in air.

[0137] Comparative Example 1

[0138] Compared with Example 1, this comparative example does not include the step of additive modification in step (1), and the remaining preparation steps and material selection are the same as those in Example 1 to obtain a blank perovskite film, which is then used to prepare a perovskite solar cell.

[0139] Comparative Example 2

[0140] Compared with Example 8, this comparative example does not include the step of modifying the additive in step (1), and the remaining preparation steps and material selection are the same as those in Example 8 to obtain a blank perovskite film, which is then used to prepare a perovskite photovoltaic module.

[0141] Test Example 1

[0142] The mesophase perovskite films of Example 1 and Comparative Example 1 were subjected to in-situ grazing incidence wide-angle X-ray scattering (GIWAXS) tests using a 1W1A diffuse scattering experimental station. The test results are shown in FIG. Figure 1 shown. Figure 1 In the table, Control represents Comparative Example 1, Target represents Example 1, see Figure 1 It can be seen that after annealing for 17s, the intermediate phase perovskite film prepared in Example 1 transforms from the δ phase to the α-cubic phase perovskite, while the phase transformation occurs in Comparative Example 1 at 26s, indicating that the perovskite film prepared in Example 1 is conducive to the faster formation of cubic phase perovskite. 3 The nucleation growth kinetics are related to the solvent evaporation rate and the phase transition pathway. The perovskite film formed by direct crystallization (ie, Example 1) has better crystal quality and photophysical properties than the film formed through an intermediate.

[0143] Test Example 2

[0144] The in-situ fluorescence detection of the mesophase perovskite films prepared in Example 1 and Comparative Example 1 was performed using a femtosecond ultrafast fluorescence spectrometer. The test results are as follows: Figure 2 As shown, Figure 2 The left, middle and right figures respectively represent the change of the fluorescence signal of the unmodified perovskite film in Comparative Example 1 and the perovskite film modified with guanidino oxalic acid molecules in Example 1 with annealing time and the change of the fluorescence signal at 780 nm with annealing time. Figure 2 In the table, Control represents Comparative Example 1, Target represents Example 1, see Figure 2It can be seen that the fluorescence intensity of the perovskite films prepared in Example 1 and Comparative Example 1 continued to increase in the first stage, indicating that the perovskite continued to crystallize; the film of Example 1 had a stronger fluorescence (PL) intensity, indicating that the perovskite film modified by the additive of the present invention had a larger grain size; then in the second stage, as the solvent evaporated from the bulk phase, the perovskite surface dissolved, and the PL intensity decreased significantly, among which the PL intensity of the perovskite film of Example 1 decreased less, indicating that the perovskite film modified by the additive of the present invention had fewer defects; the PL intensity reduction phenomenon of the film of Comparative Example 1 and the film of Example 1 lasted for about 14s and 8s, respectively, and the PL intensity increased rapidly after 19s and 13s, indicating its continued crystallization process in the annealed state (third stage).

[0145] Test Example 3

[0146] The residual DMSO content of the mesophase perovskite films prepared in Example 1 and Comparative Example 1 at different annealing times was tested using a Bruker 600 Hz nuclear magnetic resonance spectrometer. The test results are shown in FIG. Figure 3 As shown, Figure 3 The left, middle and right figures respectively represent the unmodified mesophase perovskite film in comparative example 1 and the mesophase perovskite film modified with guanidino oxalic acid molecules in example 1 under different annealing times of DMSO and FA. + of 1 H-NMR signal and DMSO and FA + The relationship between the content ratio and time. Figure 3 In the table, Control represents Comparative Example 1, Target represents Example 1, see Figure 3 It can be seen that the residual solvent content of the film prepared in Example 1 is lower than that of the film prepared in Comparative Example 1 in the same period of time; and compared with Comparative Example 1, the solvent evaporation speed of Example 1 is faster.

[0147] Test Example 4

[0148] The fluorescence spectra of the perovskite films prepared in Example 1 and Comparative Example 1 at different temperatures (80-240 K) were collected using the FLS980 transient fluorescence spectrum, and the exciton binding energy (E b ), the test results are as follows Figure 4 As shown, Figure 4 The left, middle and right figures respectively represent the pseudo-color images (80-240K) and Arrhenius fitting results of the temperature-dependent fluorescence spectra of the unmodified perovskite film in Comparative Example 1 and the perovskite film modified with guanidino oxalic acid molecules in Example 1 at different temperatures (80-240K). Figure 4 In the example, Control represents Comparative Example 1, Target represents Example 1, and Figure 4As shown, the perovskite film E prepared in Example 1 b It is lower than the perovskite film prepared in Comparative Example 1, indicating that non-radiative recombination is suppressed, which is more conducive to carrier extraction.

[0149] Test Example 5

[0150] The photoelectric performance of the solar cells prepared in Example 1 and Comparative Example 1 and the photovoltaic modules prepared in Example 8 and Comparative Example 2 were tested using a Keithley 2400 source meter and a solar simulator. -2 ) illumination conditions. A standard Si battery was used for calibration before the JV test. All test operations were performed in air. The forward and reverse sweep rate of the device was 0.1 V s -1 .

[0151] See also Figure 5 As shown in the figure, the photoelectric conversion efficiency of the solar cell prepared by the perovskite film modified by the additive in Example 1 is 25.33%, which is higher than that of the solar cell prepared by the perovskite film without the additive (23.83%, Comparative Example 1); at the same time, the device open circuit voltage (V OC ) increased from 1.165V to 1.182V, and the fill factor FF increased from 80.04% to 82.79%. It can be seen that the guanidine oxalic acid molecules used in the present invention can effectively improve the photoelectric conversion efficiency of solar cells.

[0152] See also Figure 6 As shown in the figure, the photovoltaic module prepared by using the additive-modified perovskite film in Example 8 has a photoelectric conversion efficiency of 20.48%, which is higher than the photovoltaic module prepared by using the perovskite film without the additive (18.57%, Comparative Example 2); at the same time, the module V OC The voltage increased from 17.08V to 17.72V, and the fill factor FF increased from 67.23% to 71.55%. It can be seen that the guanidine oxalic acid molecules used in the present invention can effectively improve the photoelectric conversion efficiency of the module.

[0153] Test Example 6

[0154] The stability of the solar cells prepared in Example 1 and Comparative Example 1 was tested using a Keithley 2400 source meter and a solar simulator. The storage conditions of the devices were humidity ~35±5% and temperature 25°C. Figure 7 As shown, the modified device still maintains more than 93% stability after 1000 hours, while the unmodified perovskite device decays faster, indicating that the solar cell prepared by the perovskite film modified by the additive of the present invention has excellent stability.

[0155] The above is an exemplary description of the embodiments of the present invention. However, the protection scope of the present invention is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A perovskite film, characterized in that: The perovskite film includes a guanidino oxalic acid additive.

2. The perovskite film according to claim 1, characterized in that The perovskite film also includes a perovskite material having a perovskite lattice composed of ABX3, wherein A is CH3NH3 + 、HC(NH2)2 + , Cs + and Rb + One or more of the following; B is Pb 2+ Sn 2+ At least one of - Br - , Cl - At least one of .

3. The perovskite film according to claim 2, characterized in that: The perovskite film is prepared by mixing a perovskite precursor solution and a guanidino oxalic acid additive; Preferably, the molar content of the guanidino oxalic acid additive is 0.30-0.75% of the perovskite precursor solution; Preferably, the preparation method of the guanidino oxalic acid additive comprises the following steps: The additive is obtained by mixing guanidine acetate and oxalic acid in an organic solvent.

4. The method for preparing a perovskite thin film according to any one of claims 1 to 3, characterized in that: The method comprises: (1) preparing a perovskite precursor solution; (2) mixing the perovskite precursor solution with the guanidino oxalic acid additive to obtain a mixed solution; (3) Placing the mixed solution on a substrate and subjecting it to annealing treatment to obtain the perovskite film.

5. The method according to claim 4, characterized in that In step (3), the annealing temperature is 100-150° C. and the annealing time is 15-80 min.

6. Application of the perovskite film according to any one of claims 1 to 3 in the photovoltaic field.

7. A perovskite solar cell comprising the perovskite film according to any one of claims 1 to 3; Preferably, the structure of the solar cell is a conductive substrate, an electron transport layer, the perovskite film according to any one of claims 1 to 3, a passivation layer, a hole transport layer and a metal electrode in sequence.

8. The method for preparing a perovskite solar cell according to claim 7, characterized in that: The method is: An electron transport layer, the perovskite film, a passivation layer, a hole transport layer and a metal electrode are sequentially deposited on a conductive substrate. Preferably, the method for preparing the solar cell comprises the following steps: (S1) preparing a perovskite precursor solution, and mixing the perovskite precursor liquid solution with a guanidino oxalic acid additive to obtain a mixed solution; (S2) preparing an electron transport layer on a conductive substrate and performing annealing; (S3) coating the mixed solution on the electron transport layer and heating and annealing to form the perovskite film; (S4) preparing a passivation layer on the perovskite film; (S5) preparing a hole transport layer on the passivation layer; (S6) Depositing a metal electrode onto the hole transport layer to obtain a perovskite solar cell.

9. A perovskite photovoltaic module, characterized in that: The perovskite photovoltaic module comprises the perovskite solar cell according to claim 7.

10. The method for preparing the perovskite photovoltaic module according to claim 9, characterized in that: The method comprises the following steps: assembling the perovskite solar cells to form a perovskite photovoltaic module.

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