Perovskite passivation layer and perovskite solar cell thereof

Abstract

The invention provides a perovskite passivation layer and a perovskite solar cell thereof. The perovskite active layer is arranged on the substrate, the perovskite passivation layer is arranged on the surface of the perovskite active layer, the material of the perovskite passivation layer contains 2-R-4, 5-dicyanoimidazole lithium, and R is halogenated C1-4 alkyl. The perovskite passivation layer can stabilize the perovskite structure in the solar cell, inhibit ion migration and facilitate transmission of carriers on an interface.

Description

Technical Field

[0001] The present invention relates to the field of perovskite solar cells, and in particular to a perovskite passivation layer and a perovskite solar cell thereof. Background Art

[0002] Perovskite solar cells have received great attention in the past decade due to their excellent photovoltaic performance. Their current photoelectric conversion efficiency exceeds 26%, making perovskite solar cells one of the most promising thin-film photovoltaic technologies. However, perovskite solar cells still have problems such as ion migration, non-radiative recombination, and easy decomposition and instability of the perovskite body.

[0003] King Abdullah University of Science and Technology added p-aminobenzoic acid to the perovskite solution, which binds to the uncoordinated Pb via -NH2 (amino) and -COOH (carboxyl) groups. 2+ (Lead ions) undergo Lewis acid-base reaction to form compounds, stabilize the octahedral structure, inhibit ion migration, slow down the crystallization rate, increase the grain size, and promote the formation of a uniform perovskite film with fewer defects.

[0004] Wuhan University used mixed cations of iodomethane and propylenediamine iodine to post-treat the perovskite surface, which promoted the stress release of the perovskite surface and alleviated the problem of degradation caused by the low iodine vacancy formation energy.

[0005] At present, most of the existing technologies passivate metal cations or halide anions separately to achieve the purpose of inhibiting ion migration and stabilizing the structure, but cannot effectively passivate metal cations and halide anions at the same time. Summary of the invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention provides a perovskite passivation layer and a perovskite solar cell thereof. The perovskite passivation layer of the present invention can stabilize the perovskite structure, inhibit ion migration, and also has a positive effect on the stability of the device.

[0007] The first aspect of the present invention provides a perovskite passivation layer, which is arranged on the surface of the perovskite active layer. The material of the perovskite passivation layer contains 2-R-4,5-dicyanoimidazole lithium, wherein R is a halogenated C1-4 alkyl.

[0008] In one or more embodiments, the halogen in the haloC1-4alkyl is one or more of F, Cl, Br and I.

[0009] In one or more embodiments, the halogenated C1-4 alkyl group is a C1-4 alkyl group substituted with 1 to 10 or 1 to 5 halogens.

[0010] In one or more embodiments, the lithium 2-R-4,5-dicyanoimidazole is lithium 2-trifluoromethyl-4,5-dicyanoimidazole.

[0011] In one or more embodiments, the surface density of the perovskite passivation layer is 0.0001-0.015 mg / cm 2 .

[0012] In one or more embodiments, the perovskite passivation layer has a thickness of 2-5 nm.

[0013] In one or more embodiments, the thickness of the perovskite active layer is 400-800 nm or 500-600 nm.

[0014] In one or more embodiments, the active material of the perovskite active layer contains an ABX3 compound, wherein A is a monovalent cation, such as a mixture of one or several monovalent cations selected from cesium, rubidium, methylamine, and methylamidine; B is a divalent cation, such as a mixture of one or several divalent cations selected from lead, copper, zinc, gallium, tin, and calcium; and X is a monovalent anion, such as a mixture of one or several monovalent anions selected from iodine, bromine, chlorine, fluorine, and thiocyanate.

[0015] A second aspect of the present invention provides a method for preparing a perovskite passivation layer as described in any embodiment of the present invention, the method comprising the following steps:

[0016] The passivation layer solution is coated on the surface of the perovskite active layer, and after annealing, the perovskite passivation layer is obtained, wherein the passivation layer solution contains a solvent and 2-R-4,5-dicyanoimidazole lithium, and R is a halogenated C1-4 alkyl.

[0017] In one or more embodiments, the lithium 2-R-4,5-dicyanoimidazole is lithium 2-trifluoromethyl-4,5-dicyanoimidazole.

[0018] In one or more embodiments, the coating method includes one or more processes selected from the group consisting of spin coating, blade coating, evaporation, printing, spray coating, spray pyrolysis, and slot coating.

[0019] In one or more embodiments, the solvent is selected from one or more of isopropanol, ethanol, and methanol.

[0020] In one or more embodiments, in the passivation layer solution, the mass concentration of 2-R-4,5-dicyanoimidazole lithium is 0.1 mg / ml-20 mg / ml, and R is a halogenated C1-4 alkyl group.

[0021] In one or more embodiments, the thickness of the perovskite active layer is 400-800 nm or 500-600 nm.

[0022] In one or more embodiments, the surface density of the perovskite passivation layer is 0.0001-0.015 mg / cm 2 .

[0023] In one or more embodiments, the perovskite passivation layer has a thickness of 2-5 nm.

[0024] The third aspect of the present invention provides a method for preparing a perovskite solar cell, which includes the step of preparing a perovskite passivation layer on the surface of a perovskite active layer by using the method described in any embodiment of the present invention, and before preparing the perovskite passivation layer, the step of sequentially arranging a conductive oxide layer, a hole transport layer, and a perovskite active layer on a transparent glass, and after preparing the perovskite passivation layer, the step of sequentially arranging an electron transport layer, a blocking layer, and an electrode on the surface of the perovskite passivation layer.

[0025] A fourth aspect of the present invention provides a perovskite solar cell, which is prepared by the method for preparing a perovskite solar cell as described in any embodiment of the present invention, or the perovskite solar cell includes transparent glass, a conductive oxide layer, an electron transport layer, a perovskite active layer, a perovskite passivation layer as described in any embodiment of the present invention, an electron transport layer, a hole transport layer, and an electrode arranged in sequence from bottom to top.

[0026] In one or more embodiments, the thickness of the perovskite active layer is 400-800 nm or 500-600 nm.

[0027] In one or more embodiments, the perovskite passivation layer has a thickness of 2-5 nm.

[0028] In one or more embodiments, the electron transport layer has a thickness of 10-30 nm.

[0029] In one or more embodiments, the perovskite solar cell is a single-junction perovskite solar cell or a tandem perovskite solar cell; the tandem perovskite solar cell preferably includes a two-terminal tandem cell, a three-terminal tandem cell, and a four-terminal tandem cell.

[0030] A fourth aspect of the present invention provides a use of a perovskite passivation layer as described in any embodiment herein in stabilizing a perovskite structure.

[0031] A fifth aspect of the present invention provides a use of a perovskite passivation layer as described in any embodiment herein in the preparation of a perovskite solar cell.

[0032] The sixth aspect of the present invention provides the use of 2-R-4,5-dicyanoimidazole lithium in stabilizing the perovskite structure or preparing a perovskite solar cell with improved stability, wherein R is a halogenated C1-4 alkyl. Preferably, the 2-R-4,5-dicyanoimidazole lithium is 2-trifluoromethyl-4,5-dicyanoimidazole lithium.

[0033] In one or more embodiments, the perovskite solar cell is as described in any of the embodiments herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the device structure of the perovskite solar cell prepared in Example 1. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in this article. Unless otherwise specified, all technical and scientific terms used in this article are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definitions in this article shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0037] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0038] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0039] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0040] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0041] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this document.

[0042] The inventors have found that the use of 2-haloalkyl-4,5-dicyanoimidazole lithium for interface passivation treatment on perovskite to form a passivation layer can stabilize the perovskite structure, inhibit ion migration, and facilitate carrier transmission at the interface. This is because the negatively charged imidazole group in 2-haloalkyl-4,5-dicyanoimidazole lithium can react with the lead ions (Pb 2+ ) form Lewis acid-base adducts, thereby reducing the surface defect density, while the Li + It can better enter the perovskite lattice and passivate the undercoordinated halide ions on the surface and grain boundaries through ionic interactions, stabilize the perovskite structure, and inhibit ion migration. In addition, due to its high thermal and chemical stability, this substance also has a positive effect on device stability.

[0043] Therefore, the present invention provides a perovskite passivation layer, which is arranged on the surface of the perovskite active layer. The material of the passivation layer contains 2-R-4,5-dicyanoimidazole lithium, wherein R is a halogenated C1-4 alkyl.

[0044] In the present invention, the structural formula of 2-R-4,5-dicyanoimidazole lithium is shown in the following formula I.

[0045]

[0046] In some embodiments, the halogen in the haloC1-4alkyl group may be one or more of F, Cl, Br and I.

[0047] In some embodiments, the halogenated C1-4 alkyl group may be a C1-4 alkyl group substituted with 1 to 10 or 1 to 5 halogens.

[0048] In some embodiments, the 2-R-4,5-dicyanoimidazole lithium is 2-trifluoromethyl-4,5-dicyanoimidazole lithium (LiTDI), and its structural formula is shown in Formula II below.

[0049]

[0050] In some embodiments, the surface density of the passivation layer is 0.0001-0.015 mg / cm 2 or 0.0006-0.0064mg / cm 2 .

[0051] In the present invention, the thickness of the passivation layer may be 2-5 nm.

[0052] In the present invention, the active material of the perovskite active layer contains an ABX3 compound, A is a monovalent cation, for example, a mixture of one or several monovalent cations selected from cesium, rubidium, methylamine, and methylamidine; B is a divalent cation, for example, a mixture of one or several divalent cations selected from lead, copper, zinc, gallium, tin, and calcium; and X is a monovalent anion, for example, a mixture of one or several monovalent anions selected from iodine, bromine, chlorine, fluorine, and thiocyanate.

[0053] The present invention also provides a method for preparing a perovskite passivation layer, which comprises the following steps: coating a passivation layer solution on the surface of a perovskite active layer, and annealing to obtain the perovskite passivation layer, wherein the passivation layer solution contains 2-R-4,5-dicyanoimidazole lithium and a solvent, the mass concentration of 2-R-4,5-dicyanoimidazole lithium is 0.1 mg / ml-20 mg / ml, and R is a halogenated C1-4 alkyl.

[0054] In some embodiments, 2-R-4,5-dicyanoimidazole lithium is mixed with a solvent to obtain a passivation layer solution. The type of solvent is not particularly limited and can be selected from organic solvents commonly used in the art, such as one or more selected from isopropanol, ethanol, and methanol.

[0055] In some embodiments, the mass concentration of 2-R-4,5-dicyanoimidazole lithium in the passivation layer solution is 0.1 mg / ml, 0.5 mg / ml, 0.8 mg / ml, 1 mg / ml, 8 mg / ml, 20 mg / ml or within the range formed by any two of the foregoing values.

[0056] In some embodiments, the thickness of the perovskite active layer is 400-800 nm or 500-600 nm, for example, 450 nm, 500 nm, 550 nm, 600 nm, 700 nm, 800 nm, or within a range consisting of any two of the foregoing values.

[0057] In the present invention, in some embodiments, a passivation layer solution is coated on the surface of a perovskite active layer (also referred to as a perovskite film) using a slit coating process. The coating thickness of the passivation layer solution on the surface of the perovskite active layer can be adjusted according to the target thickness of the passivation layer. In the slit coating process, the coating rate can be 15-20 mm / s. The injection rate can be 10-14 ul / s. The coating interval can be 65-75 μm.

[0058] In some embodiments of the present invention, the passivation layer solution is coated on the surface of the perovskite active layer by a spin coating process. The passivation layer solution is dynamically spin coated (but not limited to such a preparation method) on the perovskite active layer. During spin coating, the rotation speed can be 4000-6000 rpm / s, and the acceleration is 3000-5000 r / s 2 , the time is 15 to 30 seconds.

[0059] In some embodiments of the present invention, the passivation layer solution is coated on the surface of the perovskite active layer by a scraping process. The perovskite film is scraped at a scraper speed of 8-12 mm / s, a scraper interval of 95-105 um, and a time of 15-25 s.

[0060] In the present invention, the coating method may also include one or more processes of evaporation, printing, spraying, and spray pyrolysis. The parameters of these processes may be adjusted according to the target thickness of the passivation layer.

[0061] After coating, annealing is performed. The purpose of annealing is to remove the solvent. The annealing temperature is 100-150°C, such as 100-110°C. An exemplary annealing time may be 10-30 minutes. It may be placed on a hot plate, such as 100-110°C, for annealing for 4-8 minutes. After annealing, a perovskite passivation layer is obtained.

[0062] In some embodiments, the surface density of the passivation layer is 0.0001-0.015 mg / cm 2 , for example, 0.0001 mg / cm 2 , 0.0003mg / cm 2 , 0.005mg / cm 2 , 0.0006mg / cm 2 , 0.0007mg / cm 2 , 0.001mg / cm 2 , 0.005mg / cm 2 , 0.008mg / cm 2 , 0.014mg / cm 2 Or within the range formed by any two of the aforementioned values.

[0063] Perovskite solar cells

[0064] The present invention also provides a perovskite solar cell, which comprises a perovskite active layer and a perovskite passivation layer as described herein disposed on the surface of the perovskite active layer.

[0065] The present invention also provides a method for preparing a perovskite solar cell, which includes the steps of sequentially arranging a conductive oxide layer, an electron transport layer, a perovskite active layer, the perovskite passivation layer described herein, an electron transport layer, a hole transport layer and an electrode on a transparent glass from bottom to top, wherein the perovskite passivation layer described herein can be arranged by adopting the steps of preparing the perovskite passivation layer described herein.

[0066] Therefore, the perovskite solar cell of the present invention may include transparent glass, a conductive oxide layer, a hole transport layer, a perovskite active layer, a perovskite passivation layer described herein, an electron transport layer, a hole transport layer and an electrode arranged in sequence from bottom to top.

[0067] In some embodiments, the thickness of the perovskite active layer is 400-800 nm.

[0068] In some embodiments, the perovskite passivation layer has a thickness of 2-5 nm.

[0069] In some embodiments, the electron transport layer has a thickness of 10-30 nm.

[0070] In the present invention, the material of the conductive oxide layer includes at least one of FTO, ITO, and IZO. The preparation of the conductive oxide layer is not particularly limited, and a conventional method for preparing a conductive oxide layer in the art can be used, such as a magnetron sputtering process. The process parameters can be adjusted according to the target thickness of the conductive oxide layer.

[0071] In the present invention, the material of the hole transport layer includes but is not limited to NiOx, SAM (self-assembled monolayer material), etc. The preparation of the hole transport layer is not particularly limited, and the conventional method for preparing the hole transport layer in the art can be used, such as a magnetron sputtering process. The process parameters can be adjusted according to the target thickness of the hole transport layer.

[0072] In the present invention, the material of the perovskite active layer is as described above. The preparation of the perovskite active layer is not particularly limited, and the conventional method for preparing the perovskite active layer in the art can be adopted, for example, including the method of spin coating, scraping or slit coating. In some embodiments, the perovskite precursor solution is coated on the surface of the hole transport layer to obtain the perovskite active layer. The components of the perovskite precursor solution may include one or more of FAI, CsI, PbI2, CsBr, CsCl, KI, KBr, KCl, RbI, RbBr, RbCl, MAI, MABr, MACl, FABr, and FACl. In some embodiments, the components of the perovskite precursor solution include FAI, CsI, PbI2 and MACl. The mass ratio of FAI, CsI, PbI2 and MACl is preferably (150-160): (20-30): (500-510): (5-9). The concentration of the perovskite precursor solution is preferably 0.8-1.2M. In some embodiments, the perovskite precursor solution is coated on the surface of the hole transport layer in a slit coating process to obtain a perovskite active layer. The coating rate may be 25-35 mm / s. The injection rate may be 25-40 ul / s. The coating interval may be 75-85 μm. After annealing after coating, the perovskite active layer may be obtained.

[0073] In the present invention, the material of the electron transport layer includes but is not limited to C60, tin oxide, zinc oxide, titanium oxide, etc. The preparation of the electron transport layer is not particularly limited, and the conventional method for preparing the electron transport layer in the art can be used, such as a thermal evaporation process. The process parameters can be adjusted according to the target thickness of the electron transport layer.

[0074] In the present invention, the material of the barrier layer includes but is not limited to BCP, etc. The preparation of the barrier layer is not particularly limited, and the conventional method for preparing the barrier layer in the art, such as thermal evaporation, can be used. The process parameters can be adjusted according to the target thickness of the barrier layer.

[0075] The electrode includes at least one of gold, silver, copper, aluminum and carbon.

[0076] In some embodiments, the perovskite solar cell is a single-junction perovskite solar cell or a tandem perovskite solar cell. Tandem perovskite solar cells exemplarily include two-terminal tandem cells, three-terminal tandem cells, and four-terminal tandem cells.

[0077] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples can all be purchased through commercial routes.

[0078] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

[0079] Example 1: A method for preparing a perovskite battery

[0080] (1) Provide transparent glass with a thickness of 3 mm;

[0081] (2) FTO was prepared on transparent glass by magnetron sputtering with a thickness of 200 nm;

[0082] (3) NiOx was prepared by magnetron sputtering with a thickness of 20 nm;

[0083] (4) FAI, CsI, PbI2, MACl (mass ratio of 155:26:508:7) were dissolved in a mixed solvent of DMF, NMP, and ACN to obtain a 1.1 M perovskite precursor solution, and perovskite was prepared as an active layer by slit coating. The slit coating process had a coating rate of 30 mm / s, a liquid injection rate of 30 ul / s, and a gap value of 80 um. Subsequently, the solution was pre-annealed at 100 °C for 2 min and annealed at 120 °C for 20 min. The thickness was about 550 nm.

[0084] (5) LiTDI was dissolved in IPA to obtain a solution with a concentration of 0.5 mg / ml, and a perovskite passivation layer was prepared by slit coating, wherein the slit coating process had a coating rate of 17 mm / s, a liquid injection rate of 13 ul / s, a gap value of 70 um, and annealing at 100°C for 5 min, wherein the surface density of the passivation layer was 0.0003 mg / cm 2 ;Thickness is 3nm;

[0085] (6) Thermal evaporation of C60, thickness 25 nm;

[0086] (7) BCP was prepared by thermal evaporation with a thickness of 5 nm;

[0087] (8) Cu was prepared by thermal evaporation with a thickness of 90 nm.

[0088] The schematic diagram of the device structure of the prepared perovskite solar cell is shown in Figure 1 shown.

[0089] Example 2

[0090] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 0.1 mg / ml and the surface density was 0.0001 mg / cm 2 .

[0091] Example 3

[0092] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 0.8 mg / ml and the surface density was 0.0006 mg / cm 2 .

[0093] Example 4

[0094] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 1 mg / ml and the surface density was 0.0007 mg / cm 2 .

[0095] Example 5

[0096] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 8 mg / ml and the surface density was 0.005 mg / cm 2 .

[0097] Example 6

[0098] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 20 mg / ml and the surface density was 0.014 mg / cm 2 .

[0099] Example 7

[0100] The solar cell was prepared according to the method of Example 1, except that the process of LiTDI in step 5 was as follows: 90ul LiTDI solution was taken and the perovskite film was dynamically spin-coated at a rotation speed of 4000r / s and an acceleration of 4000r / s. 2 , time is 20s. After spin coating, place it on a hot stage and anneal at 100℃ for 5min.

[0101] Example 8

[0102] The solar cell was prepared according to the method of Example 1, except that the process of LiTDI in step 5 was as follows: 5ul LiTDI solution was taken and scraped on the perovskite film, the scraper speed was 10mm / s, the gap value was 100um, the time was 20s, and after the scraping was completed, it was placed on a hot stage for annealing at 100℃ for 5min. Among them, the surface density of the passivation layer was 0.0064mg / cm 2 .

[0103] Comparative Example 1

[0104] A solar cell was prepared according to the method of Example 1, except that the concentration of LiTDI in step 5 was 50 mg / ml. The surface density of the passivation layer obtained was 0.035 mg / cm2 .

[0105] The perovskite solar cells prepared in Examples 1-8 and Comparative Example 1 were subjected to photoelectric testing, the test light intensity was AM1.5G standard light intensity, the test temperature was 25±1° C., and the results were shown in Table 1 below:

[0106] Table 1. Photoelectric test results

[0107]

Claims

1. A perovskite passivation layer, characterized in that: The perovskite passivation layer is arranged on the surface of the perovskite active layer, and the material of the perovskite passivation layer contains 2-R-4,5-dicyanoimidazole lithium, wherein R is a halogenated C1-4 alkyl group.

2. The perovskite passivation layer according to claim 1, characterized in that The perovskite passivation layer satisfies one or more of the following characteristics: The halogen in the halogenated C1-4 alkyl group is one or more of F, Cl, Br and I; Halogenated C1-4 alkyl is C1-4 alkyl substituted with 1 to 10 or 1 to 5 halogens; The surface density of the perovskite passivation layer is 0.0001-0.015 mg / cm 2 .

3. The perovskite passivation layer according to claim 1 or 2, characterized in that 2-R-4,5-dicyanoimidazole lithium is 2-trifluoromethyl-4,5-dicyanoimidazole lithium.

4. A method for preparing a perovskite passivation layer according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: The passivation layer solution is coated on the surface of the perovskite active layer, and after annealing, the perovskite passivation layer is obtained; wherein the passivation layer solution contains a solvent and 2-R-4,5-dicyanoimidazole lithium, and R is a halogenated C1-4 alkyl.

5. The method according to claim 4, characterized in that: The coating method includes one or more processes of spin coating, blade coating, evaporation, printing, spray coating, spray pyrolysis, and slit coating; In the passivation layer solution, the mass concentration of 2-R-4,5-dicyanoimidazole lithium is 0.1 mg / ml-20 mg / ml, and R is a halogenated C1-4 alkyl group; The solvent is selected from one or more of isopropanol, ethanol and methanol.

6. A method for preparing a perovskite solar cell, characterized in that: The method comprises the steps of preparing a perovskite passivation layer on the surface of a perovskite active layer by the method as claimed in claim 4 or 5, and before preparing the perovskite passivation layer, sequentially arranging a conductive oxide layer, a hole transport layer, and a perovskite active layer on a transparent glass, and after preparing the perovskite passivation layer, sequentially arranging an electron transport layer, a blocking layer, and an electrode on the surface of the perovskite passivation layer.

7. A perovskite solar cell, characterized in that: It is prepared by the method for preparing a perovskite solar cell according to claim 6.

8. The perovskite solar cell according to claim 7, characterized in that: The thickness of the perovskite active layer is 400-800nm; The thickness of the perovskite passivation layer is 2-5 nm; The thickness of the electron transport layer is 10-30 nm; The perovskite solar cell is a single-junction perovskite solar cell or a stacked perovskite solar cell.

9. Use of the perovskite passivation layer according to any one of claims 1 to 3 in stabilizing a perovskite structure or preparing a perovskite solar cell.

10. Use of 2-R-4,5-dicyanoimidazole lithium for stabilizing perovskite structures or preparing perovskite solar cells with improved stability, wherein: R is a halogenated C1-4 alkyl group.

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