Perovskite layer and method for producing and using same

Abstract

The application provides a perovskite layer and a preparation method and application thereof, and the preparation method comprises the following steps: (1) preparing a peroviskite seed crystal passivation layer on a substrate; (2) epitaxially growing a single-crystal peroviskite light-absorbing layer on the peroviskite seed crystal passivation layer; and (3) preparing a peroviskite seed crystal modification layer on the single-crystal peroviskite light-absorbing layer to obtain the peroviskite layer. Through optimization of the preparation process of the peroviskite layer, the peroviskite layer with low defects and high crystallinity is obtained under the dual effects of the bottom peroviskite seed crystal passivation layer and the surface modification of the top peroviskite seed crystal solution, and the photovoltaic performance and stability of the device are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, specifically relating to a perovskite layer, its preparation method, and its application. Background Technology

[0002] Over the past few decades, tens of thousands of scientists have dedicated themselves to advancing perovskite solar cell technology, and by last year its photoelectric conversion efficiency had reached 25.7%. Due to its overwhelming advantages, such as the ability to be prepared using liquid precursors, strong light absorption, high carrier mobility and long carrier diffusion length, and the ability to be fabricated into flexible wearable devices, perovskite solar cells are considered the most promising third-generation solar cells.

[0003] However, the efficiency of perovskite devices gradually decreases over time when placed at room temperature, which greatly restricts their industrial manufacturing. This is mainly due to the presence of numerous obvious grain boundaries, crystal dislocations, and inconsistent growth orientations in the perovskite light-absorbing layer, making it extremely susceptible to damage from moisture, temperature, and oxygen, resulting in irreversible degradation.

[0004] Currently, perovskite thin film fabrication technologies can be broadly categorized into two types: one-step and two-step methods. The one-step method involves directly spin-coating or blade-coating a precursor solution onto a substrate, followed by annealing to obtain the perovskite thin film. However, during this process, the perovskite layer often fails to completely cover the substrate, and the rapid annealing reaction can cause uneven film formation, resulting in voids and large grain boundaries, leading to poor film quality and low efficiency in the fabricated battery modules. The two-step method involves first depositing a lead iodide layer on the substrate, followed by an organic cation layer, which reacts to form the perovskite thin film. However, the solvent diffusion rate is difficult to control during film formation, and the environmental conditions are highly demanding. Perovskite thin films prepared using either one-step or two-step methods are typically low-crystallinity polycrystalline films with small grain sizes and numerous grain boundaries, voids, and surface defects. Non-radiative recombination occurs, causing the open-circuit voltage and fill factor of the fabricated devices to be lower than expected, limiting the improvement of power conversion efficiency. Furthermore, ion migration is prone to occur in real-world operating environments, leading to reduced device stability and rapid device failure.

[0005] Therefore, how to prepare a perovskite thin film with low defects and high crystallinity to improve the photovoltaic performance and stability of the device is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite layer, its preparation method, and its applications. By optimizing the perovskite layer preparation process, and through the dual effects of a bottom perovskite seed passivation layer and a top perovskite seed solution surface modification, the present invention achieves a perovskite layer with low defects and high crystallinity, effectively improving the photovoltaic performance and stability of the device.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a perovskite layer, the method comprising the following steps:

[0009] (1) Prepare a perovskite seed passivation layer on the substrate;

[0010] (2) A single-crystal perovskite light-absorbing layer is epitaxially grown on the perovskite seed passivation layer;

[0011] (3) A perovskite seed crystal modification layer is prepared on the single-crystal perovskite light-absorbing layer to obtain the perovskite layer.

[0012] This invention promotes the epitaxial growth of subsequent single-crystal perovskite light-absorbing layers through a perovskite seed passivation layer. Simultaneously, a perovskite seed solution is used to modify the surface of the single-crystal perovskite light-absorbing layer, reducing surface defects and defect density, and effectively enhancing the carrier mobility of the perovskite light-absorbing layer. Therefore, under the dual effect of the bottom perovskite seed passivation layer and the top perovskite seed solution surface modification, a perovskite layer with low defects and high crystallinity is obtained, effectively improving the photovoltaic performance and stability of the device.

[0013] As a preferred embodiment of the present invention, the perovskite seed passivation layer, the single-crystal perovskite light-absorbing layer, and the perovskite seed modification layer have the same chemical composition.

[0014] In this invention, a perovskite seed passivation layer with the same chemical composition as the single-crystal perovskite light-absorbing layer is uniformly distributed on the substrate, which can form multiple induced growth sites, thereby promoting the rapid epitaxial growth of the subsequent perovskite light-absorbing layer and generating a single-crystal perovskite thin film with a large grain size.

[0015] In this invention, a perovskite seed crystal solution with the same chemical composition as the single-crystal perovskite light-absorbing layer can reduce surface defects on the interface of the light-absorbing layer caused by incomplete evaporation of organic components and solvents. The seed crystal solution dissolves and regenerates the single-crystal perovskite light-absorbing layer.

[0016] The present invention does not specifically limit the substrate, but for example, it may be conductive glass, hole transport layer or electron transport layer, etc.

[0017] Preferably, the perovskite seed passivation layer, the single-crystal perovskite light-absorbing layer, and the perovskite seed solution have the general chemical formula ABX3.

[0018] Those skilled in the art will understand that A is a monovalent cation, such as MA. + FA + 、Rb + or Cs + Any one or at least two of the following; wherein B is a divalent cation, for example, Pb 2+ and / or Sn 2+ X is a halide ion, for example, it can be Cl-. - ,Br - Or I - Any one or at least two of them.

[0019] As a preferred technical solution of the present invention, the specific steps for preparing the perovskite seed crystal passivation layer in step (1) include:

[0020] Perovskite single crystals were deposited on the surface of the substrate using a vacuum evaporation method to obtain a perovskite seed passivation layer.

[0021] This invention does not specifically limit the preparation method of perovskite single crystals. For example, it may be prepared by heating and cooling crystallization, anti-solvent assisted crystallization, or crucible thermal evaporation.

[0022] Preferably, the deposition method is multi-step deposition, which includes primary deposition and secondary deposition.

[0023] Preferably, the rate of the primary deposition is less than the rate of the secondary deposition.

[0024] In this invention, a perovskite seed passivation layer is prepared by multi-step deposition. A lower primary deposition rate can build a loose framework to reduce the internal stress of the film, while a higher secondary deposition rate can improve the purity of the film. The two work together to improve the quality of the film.

[0025] As a preferred technical solution of the present invention, the evaporation source current during the first deposition is 70-95A, for example, it can be 70A, 75A, 80A, 85A, 90A or 95A, etc.

[0026] Preferably, the evaporation rate of the perovskite single crystal during the first deposition is: For example, it could be or wait.

[0027] Preferably, the evaporation source current during the secondary deposition is 100-120A, for example, it can be 100A, 105A, 110A, 115A or 120A.

[0028] Preferably, the evaporation rate of the perovskite single crystal during the secondary deposition is: For example, it could be or wait.

[0029] Preferably, the thickness of the perovskite seed passivation layer in step (1) is 3-25 nm, for example, it can be 3 nm, 5 nm, 7 nm, 9 nm, 11 nm, 13 nm, 15 nm, 17 nm, 19 nm, 21 nm, 23 nm or 25 nm.

[0030] In this invention, if the thickness of the perovskite seed passivation layer is too thin, the framework of the seed passivation layer will be too loose and the inter-grain spacing will be too large, resulting in a slow growth rate of the perovskite light-absorbing layer film. If the thickness of the perovskite seed passivation layer is too thick, excessive stacking is likely to occur, resulting in smaller grain size and more grain boundary defects in the subsequently prepared perovskite light-absorbing layer.

[0031] As a preferred technical solution of the present invention, the epitaxial growth method in step (2) includes the following steps:

[0032] The perovskite precursor solution is coated onto the perovskite seed passivation layer, and after annealing, the single-crystal perovskite light-absorbing layer is obtained.

[0033] In this invention, the method of coating the perovskite precursor solution is not specifically limited. For example, it can be spin coating, blade coating, screen printing, or slot coating.

[0034] As a preferred technical solution of the present invention, the annealing method is step annealing, which includes primary annealing and secondary annealing.

[0035] Preferably, the temperature of the first annealing is 30-75℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃ or 75℃, etc.

[0036] Preferably, the annealing time is 5-10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0037] Preferably, the temperature of the secondary annealing is 100-200℃, for example, it can be 100℃, 120min, 140min, 160min, 180min or 200min.

[0038] Preferably, the secondary annealing time is 30-50 minutes, for example, it can be 30 minutes, 35 minutes, 40 minutes, 45 minutes or 50 minutes.

[0039] As a preferred technical solution of the present invention, the preparation method of the perovskite seed crystal modification layer in step (3) includes the solution method.

[0040] This invention uses a solution method to prepare a perovskite seed crystal modification layer. Its mechanism is to first dissolve the surface defects of the perovskite light-absorbing layer, and then passivate and regenerate the defects on the perovskite surface.

[0041] Preferably, the specific steps for preparing the perovskite seed crystal modification layer by solution method include:

[0042] The perovskite seed crystal solution is coated onto the surface of the single-crystal perovskite light-absorbing layer, and the perovskite seed crystal modification layer is obtained after thermal annealing.

[0043] Preferably, the concentration of the perovskite seed crystal solution is 0.5-2 mg / mL, for example, it can be 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL or 2 mg / mL, etc.

[0044] In this invention, if the concentration of the perovskite seed crystal solution is too low, the seed crystals cannot form a discrete distribution to completely cover the surface of the perovskite light-absorbing layer, and the passivation effect of surface resolution and regeneration of the perovskite light-absorbing layer cannot be achieved; if the concentration of the perovskite seed crystal solution is too high, a large number of seed crystals will overlap, and after the solvent evaporates, more small grains and polygrain boundaries and other defects will easily form on the surface, reducing the film quality.

[0045] Preferably, the solvent of the perovskite seed crystal solution includes any one of octylammonium iodide solution, dodecylammonium iodide solution, or butylammonium iodide solution.

[0046] The present invention does not limit the concentration of octylammonium iodide solution, dodecylammonium iodide solution or butylammonium iodide solution, for example, it can be 1 wt%.

[0047] Preferably, the temperature of the heat annealing is 120-150℃, for example, it can be 120℃, 125℃, 130℃, 135℃, 140℃, 145℃ or 150℃.

[0048] In this invention, if the heat annealing temperature is too low, the film crystallization will be poor, the grain size will be small, and the light absorption capacity will be weakened; if the heat annealing temperature is too high, the grain size will be too large, and the perovskite layer may decompose.

[0049] Preferably, the heat annealing time is 5-10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0050] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0051] (1) Grind ABX3 single crystal into crystal powder with a diameter of less than 1 mm and place it in a vacuum device. Then, use vacuum evaporation method to deposit the crystal powder stepwise on the surface of the substrate to obtain a perovskite seed passivation layer with a thickness of 3-25 nm.

[0052] Among them, the vacuum degree of the vacuum equipment is less than 7.0×10. -4 Pa, multi-step deposition includes primary and secondary deposition. The evaporation source current during primary deposition is 70-95 A, and the evaporation rate is... The evaporation source current during secondary deposition is 100-120A, and the evaporation rate is...

[0053] (2) The ABX3 precursor solution is coated on the perovskite seed passivation layer, and then annealed at 30-75℃ for 5-10 min, and annealed at 100-200℃ for 30-50 min to obtain the single crystal perovskite light-absorbing layer.

[0054] (3) Coat the surface of the single crystal perovskite light-absorbing layer with ABX3 seed crystal solution with a concentration of 0.5-2 mg / mL, perform surface modification, and then perform hot annealing at 120-150℃ for 5-10 min to obtain the perovskite layer.

[0055] In a second aspect, the present invention provides a perovskite layer, which is prepared by the preparation method described in the first aspect.

[0056] Thirdly, the present invention provides a solar cell comprising a perovskite layer as described in the second aspect.

[0057] In this invention, the solar cell is not limited. For example, it can be a perovskite solar cell, which can be a conventional perovskite solar cell or an inverted perovskite solar cell. The perovskite solar cell includes conductive glass, a transport layer, a perovskite layer and an electrode. The electrode can be a metal electrode, which can be prepared by magnetron sputtering or vacuum evaporation, or it can be a carbon electrode.

[0058] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] This invention promotes the epitaxial growth of subsequent single-crystal perovskite light-absorbing layers through a perovskite seed passivation layer. Simultaneously, a perovskite seed solution is used to modify the surface of the single-crystal perovskite light-absorbing layer, reducing surface defects and defect density, and effectively enhancing the carrier mobility of the perovskite light-absorbing layer. Therefore, under the dual effect of the bottom perovskite seed passivation layer and the top perovskite seed solution surface modification, a perovskite layer with low defects and high crystallinity is obtained, effectively improving the photovoltaic performance and stability of the device. Attached Figure Description

[0061] Figure 1 This is a comparison chart showing the stability of perovskite solar cells prepared in Application Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0063] Example 1

[0064] This embodiment provides a method for preparing a perovskite layer, the method comprising the following steps:

[0065] (1) Preparation of Cs by antisolvent-assisted crystallization 0.15 FA 0.85 PbI3 single crystal, and the Cs 0.15 FA 0.85 PbI3 single crystals are ground into crystalline powder with a diameter of 0.5 mm;

[0066] (2) Place the substrate in a vacuum evaporation apparatus and evacuate to a vacuum level of 6.0 × 10⁻⁶. -4 Pa, adjust the evaporation source current to 85A, so that the evaporation rate of the crystal powder is The evaporation thickness was 10 nm, and then the evaporation source current was adjusted to 110 A, with an evaporation rate of [missing value]. The evaporation thickness was 5 nm, and a perovskite seed passivation layer with a thickness of 15 nm was finally obtained on the substrate.

[0067] (3) Using spin coating, Cs 0.15 FA 0.85PbI3 precursor solution was spin-coated onto the perovskite seed passivation layer, and then annealed once at 55°C for 10 min and twice at 150°C for 40 min to obtain a single crystal perovskite light-absorbing layer.

[0068] (4) Using spin coating, Cs at a concentration of 0.8 mg / mL was applied. 0.15 FA 0.85 A PbI3 seed crystal solution (with 1 wt% octylammonium iodide solution as solvent) was spin-coated onto the surface of the single-crystal perovskite light-absorbing layer for surface modification, and then subjected to thermal annealing at 120°C for 5 min to obtain the perovskite layer.

[0069] Example 2

[0070] This embodiment provides a method for preparing a perovskite layer, the method comprising the following steps:

[0071] (1) Preparation of Cs by antisolvent-assisted crystallization 0.15 FA 0.85 PbI3 single crystal, and the Cs 0.15 FA 0.85 PbI3 single crystals are ground into crystalline powder with a diameter of 0.5 mm;

[0072] (2) Place the substrate in a vacuum evaporation apparatus and evacuate to a vacuum level of 6.0 × 10⁻⁶. -4 Pa, adjust the evaporation source current to 75A, so that the evaporation rate of the crystal powder is The evaporation thickness was 1 nm, and then the evaporation source current was adjusted to 100 A, with an evaporation rate of [missing value]. The evaporation thickness was 4 nm, and a perovskite seed passivation layer with a thickness of 5 nm was finally obtained on the substrate.

[0073] (3) Using spin coating, Cs 0.15 FA 0.85 PbI3 precursor solution was spin-coated onto the perovskite seed passivation layer, and then annealed once at 30°C for 10 min and twice at 100°C for 50 min to obtain a single crystal perovskite light-absorbing layer.

[0074] (4) Using spin coating, Cs at a concentration of 0.5 mg / mL was applied. 0.15 FA 0.85 A PbI3 seed crystal solution (with 1 wt% octylammonium iodide solution as solvent) was spin-coated onto the surface of the single-crystal perovskite light-absorbing layer for surface modification, and then subjected to thermal annealing at 135°C for 7 min to obtain the perovskite layer.

[0075] Example 3

[0076] This embodiment provides a method for preparing a perovskite layer, the method comprising the following steps:

[0077] (1) Preparation of Cs by antisolvent-assisted crystallization 0.15 FA 0.85 PbI3 single crystal, and the Cs 0.15 FA 0.85 PbI3 single crystals are ground into crystalline powder with a diameter of 0.5 mm;

[0078] (2) Place the substrate in a vacuum evaporation apparatus and evacuate to a vacuum level of 6.0 × 10⁻⁶. -4 Pa, adjust the evaporation source current to 95A, so that the evaporation rate of the crystal powder is The evaporation thickness was 15 nm, and then the evaporation source current was adjusted to 120 A, with an evaporation rate of [missing value]. The evaporation thickness was 10 nm, and a perovskite seed passivation layer with a thickness of 25 nm was finally obtained on the substrate.

[0079] (3) Using spin coating, Cs 0.15 FA 0.85 PbI3 precursor solution was spin-coated onto the perovskite seed passivation layer, and then annealed once at 75°C for 5 min and twice at 200°C for 30 min to obtain a single crystal perovskite light-absorbing layer.

[0080] (4) Using spin coating, Cs at a concentration of 2 mg / mL was applied. 0.15 FA 0.85 A PbI3 seed crystal solution (with 1 wt% octyl ammonium iodide solution as solvent) was spin-coated onto the surface of the single-crystal perovskite light-absorbing layer for surface modification, and then subjected to thermal annealing at 150°C for 5 min to obtain the perovskite layer.

[0081] Example 4

[0082] The difference between this embodiment and embodiment 1 is that the thickness of the perovskite seed passivation layer is 2nm by adjusting the vacuum evaporation time in step (2).

[0083] The remaining preparation methods and parameters are consistent with those in Example 1.

[0084] Example 5

[0085] The difference between this embodiment and embodiment 1 is that the thickness of the perovskite seed passivation layer is 30 nm by adjusting the vacuum evaporation time in step (2).

[0086] The remaining preparation methods and parameters are consistent with those in Example 1.

[0087] Example 6

[0088] The difference between this embodiment and embodiment 1 is that step (4) involves Cs. 0.15 FA0.85 The concentration of the PbI3 seed crystal solution was 0.3 mg / mL.

[0089] The remaining preparation methods and parameters are consistent with those in Example 1.

[0090] Example 7

[0091] The difference between this embodiment and embodiment 1 is that step (4) involves Cs. 0.15 FA 0.85 The concentration of the PbI3 seed crystal solution was 2.5 mg / mL.

[0092] The remaining preparation methods and parameters are consistent with those in Example 1.

[0093] Example 8

[0094] The difference between this embodiment and embodiment 1 is that the temperature of the heat annealing in step (4) is 100°C.

[0095] The remaining preparation methods and parameters are consistent with those in Example 1.

[0096] Example 9

[0097] The difference between this embodiment and embodiment 1 is that the temperature of the heat annealing in step (4) is 200°C.

[0098] The remaining preparation methods and parameters are consistent with those in Example 1.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 1 is that only step (3) is performed, that is, Cs is directly spin-coated onto the substrate. 0.15 FA 0.85 PbI3 precursor solution was used to obtain perovskite layer.

[0101] The remaining preparation methods and parameters are consistent with those in Example 1.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 1 is that steps (1) and (2) are not performed, that is, the perovskite seed passivation layer is not prepared.

[0104] The remaining preparation methods and parameters are consistent with those in Example 1.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 1 is that step (4) is not performed, that is, the surface of the formed single-crystal perovskite light-absorbing layer is not modified.

[0107] The remaining preparation methods and parameters are consistent with those in Example 1.

[0108] Application Example 1

[0109] This application example provides a method for fabricating a perovskite solar cell, the method comprising the following steps:

[0110] (1) Clean the FTO conductive glass and treat it with ultraviolet light for 20 min. Then, use magnetron sputtering to prepare a nickel oxide layer with a thickness of 15 nm on the surface of the FTO conductive glass as a hole transport layer.

[0111] (2) A perovskite layer is formed on the hole transport layer using the perovskite layer preparation method provided in Example 1;

[0112] (3) Using a vacuum evaporation method, C layers with a thickness of 20 nm were sequentially deposited on the perovskite layer. 60 Together with the 5nm BCP, it serves as an electron transport layer;

[0113] (4) A copper electrode with a thickness of 70 nm is deposited on the surface of the electron transport layer using a vacuum evaporation method to form an effective area of ​​1 cm². 2 The perovskite solar cell.

[0114] Application Example 2-9

[0115] The difference between Application Examples 2-9 and Application Example 1 is that the method for preparing the perovskite layer in step (2) is provided by Examples 2-9.

[0116] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0117] Application Comparative Examples 1-3

[0118] The difference between Comparative Examples 1-3 and Application Example 1 is that the method for preparing the perovskite layer in step (2) is provided by Comparative Examples 1-3.

[0119] The remaining preparation methods and parameters are consistent with those in Application Example 1.

[0120] Figure 1 A comparison graph of the stability of perovskite solar cells prepared in Application Example 1 and Comparative Example 1 is shown. As can be seen from the graph, under high temperature test conditions, the perovskite solar cell prepared in this invention has better high temperature stability than the perovskite solar cell prepared in Comparative Example 1. This shows that bottom epitaxial growth and top seed crystal solution passivation are beneficial to improving the stability of the device.

[0121] Performance testing

[0122] The perovskite solar cells prepared in Application Examples 1-9 and Comparative Examples 1-3 were subjected to photovoltaic performance and stability tests.

[0123] Photovoltaic performance testing conditions: AM1.5, 1000W / m 2 25±2℃;

[0124] Stability testing conditions: Monitoring the change in device efficiency of perovskite solar cells over time in a nitrogen environment at 85°C.

[0125] The test results are shown in Tables 1 and 2.

[0126] Table 1

[0127]

[0128]

[0129] Table 2

[0130]

[0131]

[0132] analyze:

[0133] As shown in Tables 1 and 2, by optimizing the preparation process of the perovskite layer, this invention obtains a perovskite layer with low defects and high crystallinity under the dual effects of the bottom perovskite seed passivation layer and the top perovskite seed solution surface modification, which effectively improves the device efficiency and stability.

[0134] A comparison of the data results from Application Example 1 and Application Examples 4-5 shows that if the thickness of the perovskite seed passivation layer is too thin, the ability to epitaxially grow the perovskite layer will be weakened, resulting in poor device efficiency; if the thickness of the perovskite seed passivation layer is too thick, more grain boundary defects will be generated, resulting in reduced stability during device aging.

[0135] A comparison of the data results from Application Example 1 and Application Examples 6-7 shows that if the concentration of the seed crystal solution is too low, the remelting and regeneration modification effect on the surface of the light-absorbing layer will be weakened, resulting in a decrease in the aging stability of the battery; if the concentration of the seed crystal solution is too high, polygrain boundaries and small grains will be formed after the solvent evaporates, resulting in poor thermal stability of the device.

[0136] A comparison of the data results from Application Example 1 and Application Examples 8-9 shows that if the heat annealing temperature is too low, the grain size will be small and the light absorption capacity will be weakened, resulting in low device efficiency of the battery; if the heat annealing temperature is too high, the perovskite layer will decompose, resulting in poor thermal stability of the battery.

[0137] A comparison of the data results from Application Example 1 and Comparative Application Example 1 shows that if Cs is directly spin-coated onto the hole transport layer... 0.15 FA0.85 When a PbI3 precursor solution is used to obtain a perovskite layer, the light-absorbing layer has many volumetric and surface defects, resulting in poor device efficiency and thermal stability.

[0138] A comparison of the data results from Application Example 1 and Application Comparative Example 2 shows that if the perovskite seed passivation layer is not prepared, it is not conducive to the formation of large-size single-crystal perovskite films with few grain boundary defects, resulting in poor device efficiency and thermal stability.

[0139] A comparison of the data results from Application Example 1 and Application Comparative Example 3 shows that if the surface of the formed single-crystal perovskite light-absorbing layer is not modified, it will be difficult to reduce the surface defects at the interface of the light-absorbing layer, resulting in poor device efficiency and thermal stability.

[0140] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a perovskite layer, characterized in that, The preparation method includes the following steps: (1) Prepare a perovskite seed passivation layer on the substrate; The specific steps for preparing the perovskite seed passivation layer in step (1) include: Perovskite single crystals were deposited on the surface of the substrate using a vacuum evaporation method to obtain a perovskite seed passivation layer. (2) A single-crystal perovskite light-absorbing layer is epitaxially grown on the perovskite seed passivation layer; The epitaxial growth method described in step (2) includes the following steps: The perovskite precursor solution was coated onto the perovskite seed passivation layer, and the single-crystal perovskite light-absorbing layer was obtained after annealing. (3) A perovskite seed crystal modification layer is prepared on the single-crystal perovskite light-absorbing layer to obtain the perovskite layer; The preparation method of the perovskite seed crystal modification layer in step (3) includes a solution method, and the specific steps of the solution method for preparing the perovskite seed crystal modification layer include: The perovskite seed crystal solution is coated onto the surface of the single-crystal perovskite light-absorbing layer, and the perovskite seed crystal modification layer is obtained after thermal annealing.

2. The preparation method according to claim 1, characterized in that, The perovskite seed passivation layer, the single-crystal perovskite light-absorbing layer, and the perovskite seed modification layer have the same chemical composition.

3. The preparation method according to claim 1, characterized in that, The deposition method is multi-step deposition, which includes primary deposition and secondary deposition.

4. The preparation method according to claim 1, characterized in that, The thickness of the perovskite seed passivation layer in step (1) is 3-25 nm.

5. The preparation method according to claim 1, characterized in that, The annealing method is step annealing, which includes primary annealing and secondary annealing.

6. The preparation method according to claim 5, characterized in that, The temperature for the first annealing is 30-75℃.

7. The preparation method according to claim 5, characterized in that, The annealing time for one annealing cycle is 5-10 minutes.

8. The preparation method according to claim 5, characterized in that, The temperature for the secondary annealing is 100-200℃.

9. The preparation method according to claim 5, characterized in that, The secondary annealing time is 30-50 minutes.

10. The preparation method according to claim 1, characterized in that, The concentration of the perovskite seed crystal solution is 0.5-2 mg / mL.

11. The preparation method according to claim 1, characterized in that, The solvent for the perovskite seed crystal solution includes any one of octylammonium iodide solution, dodecylammonium iodide solution, or butylammonium iodide solution.

12. The preparation method according to claim 1, characterized in that, The temperature for heat annealing is 120-150℃.

13. The preparation method according to any one of claims 1-12, characterized in that, The heat annealing time is 5-10 minutes.

14. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Grind ABX3 single crystal into crystal powder with a diameter of less than 1 mm and place it in a vacuum device. Then, use vacuum evaporation method to deposit the crystal powder stepwise on the surface of the substrate to obtain a perovskite seed passivation layer with a thickness of 3-25 nm. Among them, the vacuum degree of the vacuum equipment is less than 7.0×10. -4 Pa, multi-step deposition includes primary deposition and secondary deposition. The evaporation source current during primary deposition is 70-95A and the evaporation rate is 0.1-0.15Å / s. The evaporation source current during secondary deposition is 100-120A and the evaporation rate is 0.3-0.35Å / s. (2) The ABX3 precursor solution is coated on the perovskite seed passivation layer, and then annealed at 30-75℃ for 5-10 min, and annealed at 100-200℃ for 30-50 min to obtain the single crystal perovskite light-absorbing layer. (3) Coat the surface of the single crystal perovskite light-absorbing layer with ABX3 seed crystal solution with a concentration of 0.5-2 mg / mL, perform surface modification, and then perform hot annealing at 120-150℃ for 5-10 min to obtain the perovskite layer.

15. A perovskite layer, characterized in that, The perovskite layer is prepared using the preparation method described in any one of claims 1-14.

16. A solar cell, characterized in that, The solar cell includes the perovskite layer as described in claim 15.

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