Perovskite thin film and preparation method and application thereof

Abstract

The invention provides a perovskite thin film and a preparation method and application thereof. The preparation method comprises the following steps: providing a perovskite precursor solution; coating the perovskite precursor solution on a substrate to form a perovskite wet film; carrying out annealing treatment on the perovskite wet film to obtain a perovskite thin film; in the annealing treatment process, auxiliary airflow and an auxiliary electric field are applied at the same time, the flowing direction of the auxiliary airflow is parallel to the plane where the perovskite wet film is located, and the direction of the auxiliary electric field is perpendicular to the plane where the perovskite wet film is located. By introducing a multi-physical field coupling environment formed by the auxiliary airflow and the auxiliary electric field, the dynamic effect of the airflow and the electrostatic guiding effect of the electric field are synchronously exerted in the annealing process, and the nucleation and growth processes of the perovskite thin film are collaboratively optimized; according to the coupling technology, the crystallization orientation degree and the grain orderliness of the perovskite film can be improved, disordered migration of ions is inhibited, the defect density of the film is reduced, and the uniformity and the stability of the perovskite film are improved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, specifically relating to a perovskite thin film, its preparation method, and its application. Background Technology

[0002] Perovskite thin films, due to their excellent photoelectric properties, have shown broad application prospects in photovoltaics, photodetectors, and light-emitting diodes. Particularly in the photovoltaic field, perovskite solar cells have become a research hotspot in recent years due to their high photoelectric conversion efficiency and low-cost fabrication. According to literature reports, the certified efficiency of perovskite solar cells exceeds 27%. Furthermore, flexible perovskite solar cells have also attracted widespread attention due to their potential applications in wearable devices and photovoltaic buildings. However, the fabrication of perovskite thin films on flexible substrates faces challenges such as uniformity and stability, which directly affect device performance. The performance of perovskite thin films depends not only on their chemical composition but also on their crystallinity. For example, the defect density and grain boundary distribution in the film significantly affect charge transport efficiency and device stability. Therefore, optimizing the crystallization process of perovskite thin films is crucial for improving device performance.

[0003] While traditional perovskite thin film crystallization methods have driven the development of related fields to some extent, they still have many limitations in practical applications. Firstly, although traditional thermal annealing can effectively promote crystal growth, the lack of precise control over ion migration behavior often leads to a high defect density within the film, especially under prolonged high-temperature annealing conditions, resulting in uncoordinated Pb... 2+ The formation of Pb clusters significantly reduces the stability of the film. Secondly, while solution methods offer good process operability, their ability to control film uniformity is limited, especially when deposited on flexible substrates, where localized stress concentration and defect aggregation are prone to occur. Furthermore, traditional methods are inadequate in improving film orientation; for example, thermal annealing struggles to achieve highly preferred orientation crystallization, while solution methods are constrained by the non-uniformity of solvent evaporation rates. These shortcomings not only limit the application performance of perovskite films in photovoltaics and optoelectronic devices but also highlight the urgent need to develop novel synergistic control methods.

[0004] Therefore, how to synergistically control crystallization orientation, reduce defect density, and improve film uniformity during the preparation of perovskite thin films is a technical challenge that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a perovskite thin film, its preparation method, and its applications. This invention introduces a multi-physics coupling environment consisting of an auxiliary airflow and an auxiliary electric field, thereby simultaneously leveraging the kinetic effects of the airflow and the electrostatic guiding effect of the electric field during the annealing process to synergistically optimize the nucleation and growth process of the perovskite thin film. This coupling technology not only enables synergistic control of the perovskite thin film crystallization process, improving the crystal orientation and grain order of the perovskite film, but also effectively suppresses disordered ion migration, reduces the defect density of the film, and thus improves the uniformity and stability of the perovskite thin film. Based on the above-mentioned multi-physics coupling technology, the prepared perovskite thin film exhibits significant advantages in terms of crystal orientation, defect density, and uniformity, laying the foundation for the large-scale production of high-performance perovskite devices.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a perovskite thin film, the method comprising the following steps: Provide perovskite precursor solutions.

[0007] The perovskite precursor solution is coated onto a substrate to form a perovskite wet film.

[0008] The perovskite wet film is annealed to obtain the perovskite thin film.

[0009] During the annealing process, an auxiliary airflow and an auxiliary electric field are applied simultaneously. The flow direction of the auxiliary airflow is parallel to the plane of the perovskite wet film, and the direction of the auxiliary electric field is perpendicular to the plane of the perovskite wet film.

[0010] This invention introduces a multi-physics coupling environment consisting of an auxiliary airflow and an auxiliary electric field, thereby simultaneously leveraging the kinetic effects of the airflow and the electrostatic guiding effect of the electric field during the annealing process to synergistically optimize the nucleation and growth process of perovskite thin films. This coupling technology not only enables synergistic control of the crystallization process of perovskite thin films, improving their crystal orientation and grain order, but also effectively suppresses disordered ion migration, reduces defect density, and thus improves the uniformity and stability of the perovskite thin films. Based on the above multi-physics coupling technology, the prepared perovskite thin films exhibit significant advantages in terms of crystal orientation, defect density, and uniformity, laying the foundation for the large-scale production of high-performance perovskite devices.

[0011] In this invention, the auxiliary airflow effectively guides solute transport and promotes uniform nucleation. Its flow direction is parallel to the plane of the perovskite wet film, ensuring uniform airflow coverage across the entire film surface and improving film coverage and crystal orientation. The auxiliary electric field, perpendicular to the plane of the perovskite wet film, can regulate the migration behavior of divalent cations and halide ions in the perovskite wet film, further optimizing the grain growth direction and rate.

[0012] Preferably, the auxiliary airflow flows parallel to the upper surface of the perovskite wet film in a laminar flow manner.

[0013] Preferably, the auxiliary gas flow includes any one of nitrogen, argon, or dry air.

[0014] Preferably, the flow rate of the auxiliary airflow is 10-15 cm / s, for example, it can be 10 cm / s, 11 cm / s, 12 cm / s, 13 cm / s, 14 cm / s or 15 cm / s, etc., and the relative humidity is less than or equal to 20%RH, for example, it can be 20%RH, 15%RH, 12%RH, 10%RH or 5%RH, etc.

[0015] Preferably, the temperature of the auxiliary airflow is 20-25°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C or 25°C.

[0016] Preferably, the positive electrode of the auxiliary electric field is located on one side of the upper surface of the perovskite wet film, and the negative electrode is located on one side of the lower surface of the perovskite wet film.

[0017] Preferably, the vertical distance between the positive and negative poles of the auxiliary electric field is 1-5cm, for example, it can be 1cm, 2cm, 3cm, 4cm or 5cm, etc.

[0018] Preferably, the vertical distance between the positive and negative electrodes of the auxiliary electric field and the perovskite wet film is 1-3 cm, for example, it can be 1 cm, 2 cm or 3 cm.

[0019] Preferably, the electric field strength of the auxiliary electric field is 1-5V / μm, for example, it can be 1V / μm, 2V / μm, 3V / μm, 4V / μm or 5V / μm.

[0020] Preferably, the auxiliary electric field is a direct current electric field.

[0021] Preferably, the perovskite thin film has the general chemical formula ABX3, wherein A includes any one or a combination of at least two of formamidinium ions, methylamine ions, or cesium ions, B includes lead ions and / or tin ions, and X includes any one or a combination of at least two of chloride ions, bromide ions, or iodide ions.

[0022] Preferably, the annealing temperature is 100-150℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, and the annealing time is 5-15min, for example, 5min, 10min or 15min.

[0023] Preferably, the preparation method includes the following steps: (1) Prepare a perovskite precursor solution with a concentration of 1.1-1.7 mol / L (e.g., 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L or 1.7 mol / L, etc.).

[0024] The perovskite precursor solution was spin-coated onto a substrate, and an anti-solvent was added dropwise during the spin-coating process to obtain a perovskite wet film.

[0025] The spin coating method is either a one-step spin coating or a two-step spin coating; the antisolvent includes ethyl acetate.

[0026] (2) The perovskite wet film is transferred to the heating stage in the sealed annealing chamber, and an auxiliary airflow with a flow rate of 10-15 cm / s, a relative humidity of less than or equal to 20%RH and a temperature of 20-25℃ and an auxiliary electric field with an electric field strength of 1-5 V / μm is provided. The film is then annealed at 100-150℃ for 5-15 minutes to obtain the perovskite thin film.

[0027] The heating platform has airflow channels on both sides, allowing the auxiliary airflow to flow parallel to the upper surface of the perovskite wet film in a laminar flow manner. A positive electrode plate and a negative electrode plate are respectively arranged on the upper and lower sides of the heating platform to generate an auxiliary electric field perpendicular to the plane of the perovskite wet film. The vertical distance between the positive and negative electrode plates is 1-5 cm. The vertical distance between the positive and negative electrode plates and the perovskite wet film is independently 1-3 cm. The positive and negative electrode plates are each made of any one of stainless steel, gold-plated sheet, or copper-plated sheet.

[0028] It should be noted that the material selection for the electrode plate must take into account both conductivity and chemical stability.

[0029] In a second aspect, the present invention provides a perovskite thin film, which is prepared by the preparation method described in the first aspect.

[0030] Thirdly, the present invention provides a single-junction perovskite solar cell, the single-junction perovskite solar cell comprising a conductive substrate, a first charge transport layer, a perovskite thin film as described in the second aspect, a second charge transport layer, and an electrode stacked together.

[0031] The charges transported by the first charge transport layer and the second charge transport layer are of opposite electrical properties.

[0032] Preferably, the conductive substrate is a rigid substrate or a flexible substrate.

[0033] Preferably, the thickness of the perovskite film is 400-700 nm, for example, it can be 400 nm, 500 nm, 600 nm or 700 nm.

[0034] Preferably, an interface passivation layer is further disposed between the perovskite thin film and the second charge transport layer. The material of the interface passivation layer includes any one or a combination of at least two of phenylethylamine iodide, monoiodopiperazine, or dimethylammonium iodide. The thickness of the interface passivation layer is 1-3 nm, for example, it can be 1 nm, 2 nm, or 3 nm.

[0035] Fourthly, the present invention provides a perovskite / crystalline silicon tandem solar cell, wherein the perovskite / crystalline silicon tandem solar cell includes a crystalline silicon bottom cell and a perovskite top cell stacked together, and the crystalline silicon bottom cell and the perovskite top cell are connected by a tunnel junction.

[0036] The perovskite top cell includes the perovskite thin film as described in the second aspect.

[0037] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0038] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a multi-physics coupling environment consisting of an auxiliary airflow and an auxiliary electric field, thereby simultaneously leveraging the kinetic effects of the airflow and the electrostatic guiding effect of the electric field during the annealing process to synergistically optimize the nucleation and growth process of perovskite thin films. This coupling technology not only enables synergistic control of the crystallization process of perovskite thin films, improving their crystal orientation and grain order, but also effectively suppresses disordered ion migration, reduces defect density, and thus improves the uniformity and stability of the perovskite thin films. Based on the above multi-physics coupling technology, the prepared perovskite thin films exhibit significant advantages in terms of crystal orientation, defect density, and uniformity, laying the foundation for the large-scale production of high-performance perovskite devices. Attached Figure Description

[0039] Figure 1 This is a comparison chart of the stability of single-junction perovskite solar cells provided in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0040] 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 in any way.

[0041] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] In one specific embodiment, the present invention provides a method for preparing a perovskite thin film, the method comprising the following steps: Provide perovskite precursor solutions.

[0044] The perovskite precursor solution is coated onto a substrate to form a perovskite wet film.

[0045] The perovskite wet film is annealed to obtain the perovskite thin film.

[0046] During the annealing process, an auxiliary airflow and an auxiliary electric field are applied simultaneously. The flow direction of the auxiliary airflow is parallel to the plane of the perovskite wet film, and the direction of the auxiliary electric field is perpendicular to the plane of the perovskite wet film.

[0047] This invention introduces a multi-physics coupling environment consisting of an auxiliary airflow and an auxiliary electric field, thereby simultaneously leveraging the kinetic effects of the airflow and the electrostatic guiding effect of the electric field during the annealing process to synergistically optimize the nucleation and growth process of perovskite thin films. This coupling technology not only enables synergistic control of the crystallization process of perovskite thin films, improving their crystal orientation and grain order, but also effectively suppresses disordered ion migration, reduces defect density, and thus improves the uniformity and stability of the perovskite thin films. Based on the above multi-physics coupling technology, the prepared perovskite thin films exhibit significant advantages in terms of crystal orientation, defect density, and uniformity, laying the foundation for the large-scale production of high-performance perovskite devices.

[0048] In this invention, the auxiliary airflow effectively guides solute transport and promotes uniform nucleation. Its flow direction is parallel to the plane of the perovskite wet film, ensuring uniform airflow coverage across the entire film surface and improving film coverage and crystal orientation. The auxiliary electric field, perpendicular to the plane of the perovskite wet film, can regulate the migration behavior of divalent cations and halide ions in the perovskite wet film, further optimizing the grain growth direction and rate.

[0049] Furthermore, the auxiliary airflow flows parallel to the upper surface of the perovskite wet film in a laminar flow manner.

[0050] In this invention, laminar flow facilitates the formation of a stable and uniform gas / solid interface on the surface of the perovskite wet film, ensuring the uniformity of solvent evaporation and solute transport, thereby effectively suppressing uneven nucleation or defect aggregation that may be caused by local turbulence. This stable airflow environment can promote the orderly arrangement of precursors, guide crystal growth along the preferred orientation, and reduce stress and pinholes on the film surface caused by airflow disturbance, ultimately improving the compactness, coverage, and crystal quality of the film.

[0051] Furthermore, the auxiliary gas flow includes any one of nitrogen, argon, or dry air.

[0052] Furthermore, the flow rate of the auxiliary airflow is 10-15 cm / s, for example, it can be 10 cm / s, 11 cm / s, 12 cm / s, 13 cm / s, 14 cm / s or 15 cm / s, etc., and the relative humidity is less than or equal to 20%RH, for example, it can be 20%RH, 15%RH, 12%RH, 10%RH or 5%RH, etc.

[0053] In this invention, a suitable flow rate is conducive to achieving an efficient mass transfer process. While ensuring uniform solvent evaporation, it avoids surface disturbance or temperature gradient caused by excessive airflow. At the same time, with a suitable relative humidity, the purity and stability of the film can be further improved.

[0054] Preferably, the temperature of the auxiliary airflow is 20-25°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C or 25°C.

[0055] In this invention, limiting the temperature of the auxiliary airflow to a suitable range can synergize the effects of the airflow and the electric field, which can not only avoid non-uniform nucleation caused by drastic temperature fluctuations, but also promote the complete fusion and orderly arrangement of grains, thereby optimizing the crystallinity and structural density of the thin film.

[0056] Furthermore, the positive electrode of the auxiliary electric field is located on one side of the upper surface of the perovskite wet film, and the negative electrode is located on one side of the lower surface of the perovskite wet film.

[0057] Furthermore, the vertical distance between the positive and negative poles of the auxiliary electric field is 1-5cm, for example, it can be 1cm, 2cm, 3cm, 4cm or 5cm, etc.

[0058] In this invention, setting the vertical distance between the positive and negative electrodes of the auxiliary electric field ensures that the auxiliary electric field acts uniformly and stably on the perovskite wet film, while avoiding the risks that may arise from excessively close distance between the electrodes. Furthermore, this distance range, combined with the parallel design of the auxiliary airflow, allows the directional guiding effect of the electric field on crystal growth and the uniform control of solvent evaporation by the airflow to work synergistically, jointly promoting the orderly growth of perovskite grains and the densification of the thin film.

[0059] It should be noted that "vertical distance" refers to the shortest distance between the positive and negative electrodes.

[0060] Furthermore, the vertical distance between the positive and negative electrodes of the auxiliary electric field and the perovskite wet film is independently 1-3 cm, for example, it can be 1 cm, 2 cm or 3 cm, etc.

[0061] This invention controls the positive and negative electrodes of the auxiliary electric field to maintain a certain vertical distance from the perovskite wet film. This ensures that the auxiliary electric field acts uniformly and stably on the perovskite wet film while avoiding potential risks caused by excessively close distances between the electrodes. Furthermore, this distance range, combined with the parallel design of the auxiliary airflow, allows the directional guiding effect of the electric field on crystal growth and the uniform control of solvent evaporation by the airflow to work synergistically, jointly promoting the orderly growth of perovskite grains and the densification of the thin film.

[0062] Furthermore, the electric field strength of the auxiliary electric field is 1-5V / μm, for example, it can be 1V / μm, 2V / μm, 3V / μm, 4V / μm or 5V / μm, etc.

[0063] In this invention, a suitable electric field strength can effectively regulate the migration behavior of ions in perovskite films, thereby optimizing the grain growth direction and reducing the defect density.

[0064] Furthermore, the auxiliary electric field is a DC electric field.

[0065] Furthermore, the perovskite thin film has the general chemical formula ABX3, wherein A includes any one or a combination of at least two of formamidinium ions, methylamine ions, or cesium ions, B includes lead ions and / or tin ions, and X includes any one or a combination of at least two of chloride ions, bromide ions, or iodide ions.

[0066] Furthermore, the annealing temperature is 100-150℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, and the annealing time is 5-15min, for example, 5min, 10min or 15min.

[0067] Furthermore, the preparation method includes the following steps: (1) Prepare a perovskite precursor solution with a concentration of 1.1-1.7 mol / L (e.g., 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L or 1.7 mol / L, etc.).

[0068] The perovskite precursor solution was spin-coated onto a substrate, and an anti-solvent was added dropwise during the spin-coating process to obtain a perovskite wet film.

[0069] The spin coating method is either a one-step spin coating or a two-step spin coating; the antisolvent includes ethyl acetate.

[0070] (2) The perovskite wet film is transferred to the heating stage in the sealed annealing chamber, and an auxiliary airflow with a flow rate of 10-15 cm / s, a relative humidity of less than or equal to 20%RH and a temperature of 20-25℃ and an auxiliary electric field with an electric field strength of 1-5 V / μm is provided. The film is then annealed at 100-150℃ for 5-15 minutes to obtain the perovskite thin film.

[0071] The heating platform has airflow channels on both sides, allowing the auxiliary airflow to flow parallel to the upper surface of the perovskite wet film in a laminar flow manner. A positive electrode plate and a negative electrode plate are respectively arranged on the upper and lower sides of the heating platform to generate an auxiliary electric field perpendicular to the plane of the perovskite wet film. The vertical distance between the positive and negative electrode plates is 1-5 cm. The vertical distance between the positive and negative electrode plates and the perovskite wet film is independently 1-3 cm. The positive and negative electrode plates are each made of any one of stainless steel, gold-plated sheet, or copper-plated sheet.

[0072] It should be noted that the dimensions of the airflow channel can be adjusted and optimized according to experimental requirements, while the length is determined based on the overall dimensions of the annealing chamber. Furthermore, the inner wall of the airflow channel can be optimized to reduce airflow turbulence and thus improve the stability of the airflow direction.

[0073] It should be noted that the material selection for the electrode plate must take into account both conductivity and chemical stability.

[0074] It should be noted that the surface of the electrode plate can be polished to reduce the occurrence of partial discharge, thereby improving the uniformity of the electric field.

[0075] In another specific embodiment, the present invention provides a perovskite thin film, which is prepared by the preparation method described above.

[0076] In another specific embodiment, the present invention provides a single-junction perovskite solar cell, the single-junction perovskite solar cell comprising a conductive substrate, a first charge transport layer, a perovskite thin film as described above, a second charge transport layer, and electrodes stacked together.

[0077] The charges transported by the first charge transport layer and the second charge transport layer are of opposite electrical properties.

[0078] Furthermore, the conductive substrate can be a rigid substrate or a flexible substrate. For example, a rigid substrate may be ITO (indium tin oxide) conductive glass or FTO (fluorine-doped tin oxide) conductive glass, and a flexible substrate may be PEN (polyethylene naphthalate) substrate or PET (polyethylene terephthalate) substrate.

[0079] Furthermore, the first charge transport layer is a hole transport layer, and the second charge transport layer is an electron transport layer.

[0080] Furthermore, the hole transport layer includes a MeO-4PACz (4-(3,6-dimethoxy-9H-carbazole-9-yl)butyric acid) layer, etc.

[0081] Furthermore, the thickness of the hole transport layer is 1-5nm, for example, 1nm, 2nm, 3nm, 4nm or 5nm.

[0082] Furthermore, the electron transport layer includes C 60 layer.

[0083] Furthermore, the thickness of the electron transport layer is 10-30 nm, for example, it can be 10 nm, 15 nm, 20 nm, 25 nm or 30 nm.

[0084] Furthermore, the thickness of the perovskite film is 400-700 nm, for example, it can be 400 nm, 500 nm, 600 nm or 700 nm.

[0085] Furthermore, an interface passivation layer is provided between the perovskite thin film and the second charge transport layer. The material of the interface passivation layer includes any one or a combination of at least two of phenylethyl iodide, monoiodopiperazine, or dimethylammonium iodide. The thickness of the interface passivation layer is 1-3 nm, for example, it can be 1 nm, 2 nm, or 3 nm.

[0086] Furthermore, a hole-blocking layer is provided between the electron transport layer and the electrode.

[0087] Furthermore, the hole-blocking layer includes a tin oxide layer.

[0088] Furthermore, the electrode includes any one of an Ag electrode, an Au electrode, or a Cu electrode.

[0089] Furthermore, the thickness of the electrode is 80-120nm, for example, it can be 80nm, 90nm, 100nm, 110nm or 120nm, etc.

[0090] In another specific embodiment, the present invention provides a perovskite / crystalline silicon tandem solar cell, the perovskite / crystalline silicon tandem solar cell comprising a crystalline silicon bottom cell and a perovskite top cell stacked together, the crystalline silicon bottom cell and the perovskite top cell being connected by a tunnel junction.

[0091] The perovskite top cell includes a perovskite thin film as described above.

[0092] It should be noted that this invention does not limit the type, structure, or fabrication process of crystalline silicon bottom cells. For example, a crystalline silicon bottom cell may be an N-type crystalline silicon bottom cell. The fabrication method of an N-type crystalline silicon bottom cell includes: 1) texturing an N-type monocrystalline silicon wafer to obtain an N-type silicon wafer with a double-sided textured surface; 2) depositing intrinsic hydrogenated amorphous silicon layers on the front and back sides of the N-type silicon wafer to obtain a front passivation layer and a back passivation layer; 3) depositing a P-type hydrogenated amorphous silicon doped layer on the surface of the front passivation layer and an N-type hydrogenated amorphous silicon doped layer on the surface of the back passivation layer, thereby possessing a symmetrical bifacial cell structure.

[0093] Furthermore, the tunnel junction includes an IZO layer (indium zinc oxide).

[0094] Furthermore, the thickness of the tunnel junction is 5-15 nm, for example, it can be 5 nm, 10 nm or 15 nm.

[0095] Example 1 This embodiment provides a method for preparing a perovskite thin film, the method comprising the following steps: (1) Prepare a solution of (CH(NH2)2PbI3) with a concentration of 1.4 mol / L. 0.83 Cs 0.17 Pb(I 0.82 Br 0.18 The precursor solution (band gap of 1.68 eV) was prepared by solvent consisting of DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) in a volume ratio of 4:1.

[0096] The perovskite precursor solution was spin-coated onto a substrate. First, the spin-coating was performed at a speed of 1000 rpm for 40 seconds, and then at a speed of 3000 rpm for 20 seconds. 200 μL of ethyl acetate was added dropwise within the last 10 seconds of spin-coating to obtain a perovskite wet film.

[0097] (2) The perovskite wet film is transferred to the heating stage in the sealed annealing chamber, and an auxiliary airflow with a flow rate of 13 cm / s, a relative humidity of 20%RH and a temperature of 25°C and an auxiliary electric field with an electric field strength of 3V / μm are provided. The film is then annealed at 100°C for 10 min to obtain the perovskite thin film.

[0098] The heating platform has airflow channels on both sides to allow the auxiliary airflow to flow parallel to the upper surface of the perovskite wet film in a laminar flow manner; the auxiliary airflow is nitrogen; the auxiliary electric field is a DC electric field; positive and negative plates (connected to the positive and negative terminals of the power supply) are respectively arranged on the upper and lower sides of the heating platform to generate the auxiliary electric field perpendicular to the plane of the perovskite wet film; the vertical distance between the positive and negative plates is 4 cm; the vertical distance between the positive and negative plates and the perovskite wet film is 2 cm each; the positive and negative plates are made of stainless steel.

[0099] This embodiment also provides a single-junction perovskite solar cell, which includes a stacked ITO conductive glass, a hole transport layer, a perovskite thin film as described above, an interface passivation layer, an electron transport layer, a hole blocking layer, and an Ag electrode.

[0100] The hole transport layer is a MeO-4PACz layer with a thickness of 3 nm; the perovskite film has a thickness of 500 nm and the chemical formula is (CH(NH2)2PbI3). 0.83 Cs 0.17 Pb(I 0.82 Br 0.18 3; the material of the interface passivation layer is monoiodopiperazine, and the thickness is 2nm; the electron transport layer is C 60The layer has a thickness of 15 nm; the hole blocking layer is a tin oxide layer with a thickness of 10 nm; the Ag electrode has a thickness of 120 nm.

[0101] This embodiment also provides a method for fabricating the above-mentioned single-junction perovskite solar cell, including the following steps: (a) Provide ITO conductive glass and ultrasonically clean it with detergent, deionized water, acetone and anhydrous ethanol respectively. The ultrasonic cleaning time is 15 min for each. After cleaning, dry it.

[0102] (b) A MeO-4PACz solution with a concentration of 1 mg / mL (ethanol as solvent) was spin-coated onto the ITO conductive glass at a speed of 3000 rpm for 30 s, and then annealed at 100 °C for 10 min to obtain a hole transport layer.

[0103] (c) Using the preparation method described above, a perovskite thin film with a thickness of 500 nm is prepared on the hole transport layer.

[0104] (d) The interface passivation solution with a concentration of 0.3 mg / mL was spin-coated onto the perovskite film at a speed of 5000 rpm for 30 s, and then annealed at 100 °C for 10 min to obtain the interface passivation layer.

[0105] (e) Using a thermal evaporation method, C layers with a thickness of 15 nm are sequentially deposited on the interface passivation layer. 60 The structure consists of a 10nm thick tin oxide layer and a 120nm thick Ag electrode.

[0106] Example 2 The difference between this embodiment and Embodiment 1 is that the vertical distance between the positive electrode plate and the negative electrode plate is 1 cm.

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

[0108] Example 3 The difference between this embodiment and Embodiment 1 is that the vertical distance between the positive electrode plate and the negative electrode plate is 5cm.

[0109] The remaining preparation methods and parameters are consistent with those in Example 1.

[0110] Example 4 The difference between this embodiment and Embodiment 1 is that the flow rate of the auxiliary airflow is 10 cm / s.

[0111] The remaining preparation methods and parameters are consistent with those in Example 1.

[0112] Example 5 The difference between this embodiment and Embodiment 1 is that the flow rate of the auxiliary airflow is 15 cm / s.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Example 6 The difference between this embodiment and Embodiment 1 is that the electric field strength of the auxiliary electric field is 1V / μm.

[0115] The remaining preparation methods and parameters are consistent with those in Example 1.

[0116] Example 7 The difference between this embodiment and Embodiment 1 is that the electric field strength of the auxiliary electric field is 5V / μm.

[0117] The remaining preparation methods and parameters are consistent with those in Example 1.

[0118] Example 8 The difference between this embodiment and Embodiment 1 is that this embodiment provides a perovskite / crystalline silicon tandem solar cell. The perovskite / crystalline silicon tandem solar cell includes a crystalline silicon bottom cell and a perovskite top cell stacked together. The crystalline silicon bottom cell and the perovskite top cell are connected by a tunnel junction, which is an IZO layer with a thickness of 10 nm.

[0119] The fabrication method of the perovskite / crystalline silicon tandem solar cell includes: (i) A 150 μm thick N-type single crystal silicon is sequentially pre-cleaned with ozone and deionized water, post-cleaned with a mixture of ozone and hydrofluoric acid, and finally cleaned and etched with a mixture of hydrofluoric acid and nitric acid to form an N-type crystal silicon wafer with double-sided textured surface.

[0120] (ii) Using the PECVD method, an intrinsic hydrogenated amorphous silicon passivation layer with a thickness of 2 nm is deposited on both the front and back sides of an N-type crystalline silicon wafer to form a front passivation layer on the front side of the N-type crystalline silicon wafer and a back passivation layer on the back side of the N-type crystalline silicon wafer. Then, a P-type hydrogenated amorphous silicon doped layer with a thickness of 9 nm and an N-type hydrogenated amorphous silicon doped layer with a thickness of 6 nm are deposited on the front and back sides respectively, thus forming a symmetrical bifacial cell structure.

[0121] (iii) A 10 nm thick IZO layer is deposited on the N-type hydrogenated amorphous silicon doped layer as a tunnel junction.

[0122] (iv) Using the preparation method described in Example 1, a hole transport layer, a perovskite thin film, an interface passivation layer, an electron transport layer, and a hole blocking layer are sequentially prepared on the tunnel junction.

[0123] (v) Using PVD, an IZO layer with a thickness of 40 nm is deposited on the hole blocking layer, and an ITO layer with a thickness of 100 nm is prepared on the P-type hydrogenated amorphous silicon doped layer.

[0124] (vi) Using screen printing, Ag gate lines with a thickness of 180 nm are screen printed on the ITO layer and then sintered and cured.

[0125] A 1 μm thick Ag layer and a 90 nm thick MgF2 layer were sequentially deposited on the IZO layer described in step (v) using a thermal evaporation method.

[0126] The remaining preparation methods and parameters are consistent with those in Example 1.

[0127] Example 9 The difference between this embodiment and Embodiment 1 is that the flow rate of the auxiliary airflow is 8 cm / s.

[0128] The remaining preparation methods and parameters are consistent with those in Example 1.

[0129] Example 10 The difference between this embodiment and Embodiment 1 is that the flow rate of the auxiliary airflow is 18 cm / s.

[0130] The remaining preparation methods and parameters are consistent with those in Example 1.

[0131] Example 11 The difference between this embodiment and Embodiment 1 is that the temperature of the auxiliary airflow is 15°C.

[0132] The remaining preparation methods and parameters are consistent with those in Example 1.

[0133] Example 12 The difference between this embodiment and Embodiment 1 is that the temperature of the auxiliary airflow is 30°C.

[0134] The remaining preparation methods and parameters are consistent with those in Example 1.

[0135] Example 13 The difference between this embodiment and Embodiment 1 is that the vertical distance between the positive and negative poles of the auxiliary electric field is 0.5 cm.

[0136] The remaining preparation methods and parameters are consistent with those in Example 1.

[0137] Example 14 The difference between this embodiment and Embodiment 1 is that the vertical distance between the positive and negative poles of the auxiliary electric field is 6 cm.

[0138] The remaining preparation methods and parameters are consistent with those in Example 1.

[0139] Example 15 The difference between this embodiment and Embodiment 1 is that the electric field strength of the auxiliary electric field is 0.5V / μm.

[0140] The remaining preparation methods and parameters are consistent with those in Example 1.

[0141] Example 16 The difference between this embodiment and Embodiment 1 is that the electric field strength of the auxiliary electric field is 5.5V / μm.

[0142] The remaining preparation methods and parameters are consistent with those in Example 1.

[0143] Comparative Example 1 The difference between this comparative example and Example 1 is that no auxiliary airflow and auxiliary electric field are set during the annealing process described in step (2).

[0144] The remaining preparation methods and parameters are consistent with those in Example 1.

[0145] Stability tests were conducted on the single-junction tackifier solar cells provided in Example 1 and Comparative Example 1. The test conditions included a temperature of 25°C, a relative humidity of 0%, and a time of 1000 hours. The test results are as follows: Figure 1 As shown in the figure, after 1000 hours of continuous illumination, the photoelectric conversion efficiency of the single-junction tack crystal solar cell provided in Example 1 can still be maintained at more than 92% of the initial efficiency, while the photoelectric conversion efficiency of the single-junction tack crystal solar cell provided in Comparative Example 1 is only maintained at about 70% of the initial efficiency.

[0146] Comparative Example 2 The difference between this comparative example and Example 1 is that no auxiliary airflow is set during the annealing process described in step (2).

[0147] The remaining preparation methods and parameters are consistent with those in Example 1.

[0148] Comparative Example 3 The difference between this comparative example and Example 1 is that no auxiliary electric field is set during the annealing process described in step (2).

[0149] The remaining preparation methods and parameters are consistent with those in Example 1.

[0150] Performance testing The photoelectric performance of the single-junction tackey cell or perovskite / crystalline silicon tandem cell provided in the above embodiments and comparative examples was tested under the following conditions: AM1.5, 1000 W / m 2 , 25±2℃.

[0151] The test results are shown in Table 1.

[0152] Table 1 analyze: As shown in Table 1, this invention introduces a multi-physics coupling environment consisting of an auxiliary airflow and an auxiliary electric field, thereby simultaneously leveraging the dynamic effects of the airflow and the electrostatic guiding effect of the electric field during the annealing process to synergistically optimize the nucleation and growth process of the perovskite thin film. This coupling technology not only enables synergistic control of the crystallization process of the perovskite thin film, improving its crystal orientation and grain order, but also effectively suppresses disordered ion migration, reduces the defect density of the film, and thus improves the uniformity and stability of the perovskite thin film. Based on the above multi-physics coupling technology, the prepared perovskite thin film exhibits significant advantages in terms of crystal orientation, defect density, and uniformity. The photoelectric conversion efficiency of the single-junction perovskite solar cell prepared based on this technology can reach 22.73%, and the photoelectric conversion efficiency of the perovskite / crystalline silicon tandem cell can be improved to 32.96%.

[0153] As can be seen from the comparison between Example 1 and Examples 9-10, if the flow rate of the auxiliary airflow is too low, the solvent in the perovskite cannot be removed in time, and perovskite crystal pores are easily formed; if the flow rate of the auxiliary airflow is too high, the perovskite solvent is removed too quickly, resulting in perovskite grains that are too small.

[0154] As can be seen from the comparison between Example 1 and Examples 11-12, if the temperature of the auxiliary gas flow is too low, the solvent in the perovskite cannot be removed in time, which easily leads to the formation of perovskite crystal pores; if the temperature of the auxiliary gas flow is too high, the perovskite solvent is removed too quickly, resulting in perovskite grains that are too small.

[0155] As can be seen from the comparison between Example 1 and Examples 13-14, if the vertical distance between the positive and negative electrodes of the auxiliary electric field is too short, the electric field strength will be too large, which will disrupt the dynamic equilibrium of perovskite crystallization. An excessively strong vertical electric field will accumulate a large amount of charge on the surface of the film, which will directly damage the surface morphology of the film, forming pinholes or pits, resulting in a decrease in the density of the film. If the vertical distance between the positive and negative electrodes of the auxiliary electric field is too long, the electric field strength will be too small, which is insufficient to overcome the disorder of ion thermal motion (Brownian motion) and the resistance of the solvation layer. Ions will not be able to arrange themselves in an orderly manner in the direction of the electric field. At this time, crystal growth reverts to the traditional random growth mode, and it is impossible to obtain grains with high orientation, and thus it is impossible to effectively suppress the disordered migration of ions.

[0156] A comparison of Examples 1 and 15-16 shows that if the electric field strength of the auxiliary electric field is too small, it is insufficient to overcome the disorder of ion thermal motion (Brownian motion) and the resistance of the solvation layer, and the ions will not be able to arrange themselves in an orderly manner along the electric field direction. At this time, crystal growth reverts to the traditional random growth mode, and it is impossible to obtain grains with high orientation, thus failing to effectively suppress the disordered migration of ions. If the electric field strength of the auxiliary electric field is too large, it will disrupt the perovskite crystallization kinetic equilibrium. An excessively strong vertical electric field will accumulate a large amount of charge on the film surface, which will directly damage the surface morphology of the film, forming pinholes or pits, leading to a decrease in the film's density.

[0157] As can be seen from the comparison between Example 1 and Comparative Example 1, if the perovskite wet film is annealed directly without any auxiliary means, the ability to control the crystallization of perovskite is weak, and the perovskite grains are too small or too many pinholes are generated.

[0158] As can be seen from the comparison between Example 1 and Comparative Examples 2-3, if only an auxiliary electric field is used, solvent evaporation is hindered and perovskite crystallization kinetics become unbalanced; if only an auxiliary airflow is used, it is difficult to control the orientation of perovskite crystallization.

[0159] It should be noted that the present invention is illustrated through 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, additions 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 thin film, characterized in that, The preparation method includes the following steps: Provide perovskite precursor solutions; The perovskite precursor solution is coated onto a substrate to form a perovskite wet film. The perovskite wet film is annealed to obtain the perovskite thin film; During the annealing process, an auxiliary airflow and an auxiliary electric field are applied simultaneously. The flow direction of the auxiliary airflow is parallel to the plane of the perovskite wet film, and the direction of the auxiliary electric field is perpendicular to the plane of the perovskite wet film.

2. The preparation method according to claim 1, characterized in that, The auxiliary airflow flows parallel to the upper surface of the perovskite wet film in a laminar flow manner; And / or, the auxiliary gas flow includes any one of nitrogen, argon, or dry air; And / or, the flow rate of the auxiliary airflow is 10-15 cm / s, and the relative humidity is less than or equal to 20% RH; And / or, the temperature of the auxiliary airflow is 20-25°C.

3. The preparation method according to claim 1 or 2, characterized in that, The positive electrode of the auxiliary electric field is located on one side of the upper surface of the perovskite wet film, and the negative electrode is located on one side of the lower surface of the perovskite wet film. The vertical distance between the positive and negative poles of the auxiliary electric field is 1-5 cm; The vertical distance between the positive and negative electrodes of the auxiliary electric field and the perovskite wet film is 1-3 cm each.

4. The preparation method according to any one of claims 1-3, characterized in that, The electric field strength of the auxiliary electric field is 1-5V / μm; And / or, the auxiliary electric field is a DC electric field.

5. The preparation method according to any one of claims 1-4, characterized in that, The chemical formula of the perovskite thin film is ABX3, wherein A includes any one or at least two of the formamidinium ion, methylamine ion or cesium ion neutralization, B includes lead ion and / or tin ion, and X includes any one or at least two of the chloride ion, bromide ion or iodide ion. And / or, the annealing temperature is 100-150℃, and the annealing time is 5-15 min.

6. The preparation method according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Prepare a perovskite precursor solution with a concentration of 1.1-1.7 mol / L; The perovskite precursor solution was spin-coated onto a substrate, and an anti-solvent was added dropwise during the spin-coating process to obtain a perovskite wet film. The spin coating method is either a one-step spin coating or a two-step spin coating; the antisolvent includes ethyl acetate; (2) The perovskite wet film is transferred to the heating stage in the closed annealing chamber, and an auxiliary airflow with a flow rate of 10-15 cm / s, a relative humidity of less than or equal to 20%RH and a temperature of 20-25℃ and an auxiliary electric field with an electric field strength of 1-5 V / μm is provided. The film is then annealed at 100-150℃ for 5-15 min to obtain a perovskite thin film. The heating platform has airflow channels on both sides, allowing the auxiliary airflow to flow parallel to the upper surface of the perovskite wet film in a laminar flow manner. A positive electrode plate and a negative electrode plate are respectively arranged on the upper and lower sides of the heating platform to generate an auxiliary electric field perpendicular to the plane of the perovskite wet film. The vertical distance between the positive and negative electrode plates is 1-5 cm. The vertical distance between the positive and negative electrode plates and the perovskite wet film is independently 1-3 cm. The positive and negative electrode plates are each made of any one of stainless steel, gold-plated sheet, or copper-plated sheet.

7. A perovskite thin film, characterized in that, The perovskite thin film is prepared by the preparation method according to any one of claims 1-6.

8. A single-junction perovskite solar cell, characterized in that, The single-junction perovskite solar cell includes a conductive substrate, a first charge transport layer, a perovskite thin film as described in claim 7, a second charge transport layer, and an electrode stacked together. The charges transported by the first charge transport layer and the second charge transport layer are of opposite electrical properties.

9. The single-junction perovskite solar cell according to claim 8, characterized in that, The conductive substrate is a rigid substrate or a flexible substrate; And / or, the thickness of the perovskite film is 400-700 nm; And / or, an interface passivation layer is further disposed between the perovskite thin film and the second charge transport layer, wherein the material of the interface passivation layer includes any one or a combination of at least two of phenylethylamine iodide, monoiodopiperazine or dimethylammonium iodide; and the thickness of the interface passivation layer is 1-3 nm.

10. A perovskite / crystalline silicon tandem solar cell, characterized in that, The perovskite / crystalline silicon tandem solar cell includes a crystalline silicon bottom cell and a perovskite top cell stacked together, and the crystalline silicon bottom cell and the perovskite top cell are connected by a tunnel junction. The perovskite top cell includes the perovskite thin film as described in claim 7.

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