Perovskite solar cell and preparation method thereof

Abstract

The invention discloses a perovskite solar cell and a preparation method thereof.The perovskite solar cell comprises a substrate, a first charge transport layer, a perovskite absorption layer, a second charge transport layer and a first electrode which are sequentially arranged in a stacked mode, the first charge transport layer comprises a first film layer and a second film layer which are arranged in a stacked mode, the second film layer is located on the layer, away from the substrate, of the first film layer, the first film layer comprises an N-type semiconductor material, the second film layer comprises a self-assembly monomolecular material and an additive, and the first charge transport layer and the second charge transport layer are made of different semiconductor materials. The problems of low efficiency and long-term stability of a large-size perovskite solar cell in the prior art are solved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a perovskite solar cell and a method for preparing the same. Background Art

[0002] The current density of perovskite / silicon tandem solar cells depends on the minimum current of the top cell and the bottom cell. Usually, the thickness of the functional film layer (such as the electron transport layer, the hole transport layer, the tunneling layer, the transparent conductive layer, etc.) will produce a large parasitic absorption, affecting the current density of the top and bottom cells. Therefore, while ensuring that the main performance of the battery is not affected, the thickness of the functional film layer is kept as thin as possible. At present, many perovskite / silicon tandem solar cells only choose to use a self-assembled monolayer (SelfAssembled Monolayer, referred to as SAM) layer as a hole outgoing layer (such as 2PACz, Me-4PACz, etc.), which can greatly improve the current density of the bottom cell. However, SAM materials usually have hydroxyl functional groups, and their weak acidity will corrode the ITO of the lower tunneling layer, resulting in serious composite loss of the battery interface and poor long-term stability.

[0003] In addition, since the SAM material is deposited in a way that it forms an anchor with the underlying oxide layer, this bonding method will not fully cover the substrate, and the deposition quality of the SAM layer will affect the deposition quality of the upper perovskite layer. There are many defects between the SAM layer and the perovskite layer, resulting in serious interface composite losses and affecting device performance. Summary of the invention

[0004] The present application provides a perovskite solar cell and a preparation method thereof to solve the problems of low efficiency and long-term stability of large-size perovskite solar cells in the related art.

[0005] According to one aspect of the present application, a perovskite solar cell is provided, comprising a substrate, a first charge transport layer, a perovskite absorption layer, a second charge transport layer and a first electrode which are sequentially stacked, wherein the first charge transport layer comprises a first film layer and a second film layer which are stacked, the second film layer is located at a layer of the first film layer away from the substrate, the first film layer comprises an N-type semiconductor material, the second film layer comprises a self-assembled monomolecular material and an additive, and the first charge transport layer and the second charge transport layer have different semiconductor materials.

[0006] Optionally, a thickness of the second film layer in a stacking direction is less than or equal to a thickness of the first film layer in the stacking direction, wherein the stacking direction is a direction from the substrate to the first electrode.

[0007] Optionally, the thickness of the first film layer in the stacking direction is 1-10 nm.

[0008] Optionally, the N-type semiconductor material includes one or more materials selected from zinc oxide, titanium oxide, gallium nitride, tin oxide, indium gallium zinc oxide, fluorine-doped tin oxide, and fluorine-doped indium oxide.

[0009] Optionally, the first film layer is the N-type semiconductor material, and the first charge transport layer is an electron transport layer.

[0010] Optionally, the additive includes an amino functional group and a methylsilane functional group.

[0011] Optionally, the perovskite absorption layer includes a third film layer and a fourth film layer stacked on top of each other. The fourth film layer is located on the side of the third film layer away from the second film layer. The material of the third film layer includes a two-dimensional perovskite material, and the material of the fourth film layer includes a three-dimensional perovskite material. Among them, the two-dimensional perovskite material is formed by the reaction of the amino functional group with the three-dimensional perovskite material.

[0012] According to another aspect of the present application, a method for preparing a perovskite solar cell is provided, including: providing a substrate; sequentially forming a stacked first film layer, a second film layer, a perovskite absorption layer, a second charge transport layer, and a first electrode on the substrate. Among them, the first film layer and the second film layer constitute the first charge transport layer. The second film layer is located on the layer of the first film layer away from the substrate. The first film layer includes an N-type semiconductor material, and the second film layer includes a self-assembled monolayer material.

[0013] Optionally, the process for forming the first film layer includes one or more of physical vapor deposition, atomic layer deposition, and evaporation coating processes. The thickness of the first film layer is 1 to 10 nm. The process for forming the second film layer includes one of coating process, doctor blade coating process, spraying process, inkjet process, and inline machine deposition process. The second film layer includes a self-assembled monolayer material.

[0014] Optionally, the step of forming the perovskite absorption layer includes: generating a three-dimensional perovskite material layer on the second film layer to form a fourth film layer. The second film layer includes a self-assembled monolayer material and an additive. The additive reacts with the three-dimensional perovskite material layer to generate a two-dimensional perovskite layer to form a third film layer. The third film layer and the fourth film layer constitute the perovskite absorption layer.

[0015] Applying the technical solution of the present application, a perovskite solar cell is provided. In this perovskite solar cell, the first film layer in the first charge transport layer comprises an N-type semiconductor material. Then, the first charge transport layer is used for electron transport and matches the substrate as the electron transport layer (ETL) of the perovskite cell to facilitate the transfer of electrons from the perovskite absorption layer to the substrate. Moreover, the second film layer comprises self-assembled monolayer materials and additives, which can increase the current density of the substrate. At the same time, the first film layer can passivate the interfacial defects between the perovskite absorption layer and the second film layer, reduce non-radiative recombination, improve the charge collection efficiency, and extend the lifespan of the cell. In addition, since the first film layer is located between the substrate and the second film layer, it can also act as a protective layer to prevent the corrosive chemicals in the second film layer from directly contacting the substrate material, avoid interfacial corrosion, and enhance the long-term stability of the cell, thereby solving the problems of low efficiency and long-term stability of large-size perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0017] Figure 1 is a schematic cross-sectional structure diagram of a single-junction perovskite solar cell according to an embodiment of this application;

[0018] Figure 2 is a schematic cross-sectional structure diagram of a tandem perovskite solar cell according to an embodiment of this application;

[0019] Figure 3 is a flowchart of a preparation method of a perovskite solar cell according to an embodiment of this application.

[0020] Among them, the above-mentioned drawings include the following reference numerals:

[0021] 10. Substrate; 111. Bottom TCO film layer; 112. First hydrogenated amorphous silicon layer; 1131. First intrinsic hydrogenated amorphous silicon layer; 1132. Second intrinsic hydrogenated amorphous silicon layer; 114. Monocrystalline silicon layer; 115. Second hydrogenated amorphous silicon layer; 116. Second electrode; 20. First charge transport layer; 21. First film layer; 22. Second film layer; 30. Perovskite absorption layer; 31. Third film layer; 32. Fourth film layer; 40. Second charge transport layer; 50. First electrode; 60. Bottom electrode; 70. Tunneling layer; 80. Buffer layer; 90. Transparent conductive layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs.

[0023] It should be noted that the terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of the present application described herein. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0025] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element can be directly on the other element or there can also be intervening elements. Also, in the description and claims, when an element is described as "connected" to another element, the element can be "directly connected" to the other element or "connected" to the other element through a third element.

[0026] As introduced in the background art, SAM materials in the prior art usually have hydroxyl-functional groups, and their weak acidity will corrode the ITO of the underlying tunneling layer, resulting in serious interfacial recombination losses in the battery, poor long-term stability, and there are many defects between the SAM layer and the perovskite layer, causing serious interfacial recombination losses and affecting device performance. To solve the above problems, the present application provides a perovskite solar cell and a preparation method thereof.

[0027] According to one aspect of the present application, there is provided a perovskite solar cell, as Figures 1 to 2As shown, it includes a substrate 10, a first charge transport layer 20, a perovskite absorption layer 30, a second charge transport layer 40 and a first electrode 50 which are stacked in sequence, wherein the first charge transport layer 20 includes a first film layer 21 and a second film layer 22 which are stacked, the second film layer 22 is located at a layer of the first film layer 21 away from the substrate 10, the first film layer 21 includes an N-type semiconductor material or a P-type semiconductor material, the second film layer 22 includes a self-assembled monomolecular material and an additive, and the first charge transport layer 20 and the second charge transport layer 40 have different semiconductor materials. In the perovskite solar cell, the first film layer in the first charge transport layer includes an N-type semiconductor material, and the first charge transport layer is used for electron transport, and is matched with the substrate as the electron transport layer (ETL) of the perovskite cell to promote the transfer of electrons from the perovskite absorption layer to the substrate. In addition, the second film layer includes self-assembled monomolecular materials and additives, which can increase the current density of the substrate. At the same time, the first film layer can passivate the interface defects between the perovskite absorption layer and the second film layer, reduce non-radiative recombination, improve the charge collection efficiency, and extend the life of the battery. In addition, since the first film layer is located between the substrate and the second film layer, it can also serve as a protective layer to prevent the corrosive chemicals in the second film layer from directly contacting the substrate material, avoiding interface corrosion, and improving the long-term stability of the battery, thereby solving the problem of low efficiency and long-term stability of large-size perovskite solar cells.

[0028] In some optional embodiments, the first film layer includes a p-type semiconductor material. When the first film layer is a p-type semiconductor material, the first film layer is used as a hole transport layer (HTL) to match the p-type layer in the substrate to optimize the transport of holes from the perovskite layer to the silicon bottom cell.

[0029] In some optional embodiments, the perovskite solar cell is as follows Figure 1 The perovskite single-cell solar cell shown, wherein the substrate 10 may include a glass substrate, specifically, the perovskite solar cell may include FTO conductive glass, ITO conductive glass, AZO conductive glass and a conductive flexible substrate. A bottom electrode 60 is provided between the substrate 10 and the first charge transport layer 20. The preparation process of the perovskite single-cell solar cell is mature, and large-area preparation can be achieved, and it has high stability.

[0030] Specifically, the material of the bottom electrode includes but is not limited to one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide-doped indium (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO) and zinc-doped tin oxide (ZTO). The bottom electrode can transfer electrons through the electron transport layer to generate current.

[0031] In some other alternative embodiments, the perovskite solar cell in the present application is a perovskite tandem solar cell structure, wherein the substrate is a solar bottom cell, and the solar bottom cell includes an intrinsic thin-film heterojunction (HJT) bottom cell, i.e., a solar crystalline silicon bottom cell, a tunnel oxide passivated contact (Topcon) bottom cell, an interdigitated back contact (IBC) bottom cell, and an ABC bottom cell.

[0032] Exemplarily, as Figure 2 shown, the substrate 10 in the perovskite solar cell can be an HJT bottom cell, and the HJT bottom cell can include: a bottom TCO film layer 111, and a first hydrogenated amorphous silicon layer 112, a first intrinsic hydrogenated amorphous silicon layer 1131, a single-crystalline silicon layer 114, a second intrinsic hydrogenated amorphous silicon layer 1132, and a second hydrogenated amorphous silicon layer 115 that are sequentially stacked and formed on the first surface of the bottom TCO film layer 111 along a direction perpendicular to the first surface. The surface of the second hydrogenated amorphous silicon layer 115 facing away from the bottom TCO film layer 111 is the front surface of the bottom cell, i.e., the front surface of the substrate 10. The solar bottom cell may further include a second electrode 116 formed on the back surface of the bottom TCO film layer 111.

[0033] In the above example, as Figure 2 shown, a tunneling layer 70 is required for electrical connection between the crystalline silicon bottom cell and the perovskite cell. The material of the tunneling layer 70 includes, but is not limited to, one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide doped (In2O3:H), aluminum-doped zinc oxide (AZO), indium zirconium oxide (IZrO), and zinc-doped tin oxide (ZTO), which can effectively recombine electrons and holes with minimal resistance loss and ensure high optical transparency in the long-wavelength band.

[0034] In some alternative embodiments, as Figures 1 to 2 shown, a buffer layer 80 and a transparent conductive layer 90 are further included between the second charge transport layer 40 and the first electrode 50. The function of the buffer layer 80 is to reduce the problems of charge accumulation and interface energy level mismatch caused by the interface effect between the second charge transport layer and the perovskite absorption layer, and improve the efficiency of the solar cell. The transparent conductive layer 90 has good electrical conductivity and transparency, can effectively transfer electrons and allow light to penetrate into the perovskite layer, and at the same time plays a role in protecting the perovskite layer to prevent it from being eroded or damaged by the external environment.

[0035] Among them, the material of the passivation layer has the same semiconductor material as the second charge transport layer, and the material of the conductive layer includes but is not limited to one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO), and zinc-doped tin oxide (ZTO).

[0036] In some alternative embodiments, such as Figures 1 to 2 shown, the thickness H2 of the second film layer 22 in the stacking direction A is less than or equal to the thickness H1 of the first film layer 21 in the stacking direction A, where the stacking direction A is the direction from the substrate 10 to the first electrode 50.

[0037] Specifically, the self-assembled monolayers of the second film layer form stable chemical bonds with the surface of the first film layer. The second film layer has a relatively thin thickness. The self-assembled monolayers can not only form chemical anchoring with other film layers to improve the contact between the upper and lower layer materials, but also effectively passivate surface defects, reduce non-radiative recombination at the interface, increase the carrier lifetime, and thus improve the charge transport efficiency and the open-circuit voltage and fill factor of the battery. Since the self-assembled monolayers have very little absorption of incident light, the relatively thin second film layer can reduce the loss of light in the battery and improve the light utilization rate and the photoelectric conversion efficiency of the battery. Moreover, the material of the second film layer is expensive and the preparation is complex, and the preparation of the relatively thin second film layer is more economical and convenient for large-scale production.

[0038] Among them, the thickness of the second film layer is 1-2 nm, which is not limited in this application.

[0039] In some alternative embodiments, the thickness of the first film layer in the stacking direction is 1-10 nm.

[0040] Specifically, the thickness of the first film layer is 1-10 nm, which has a relatively small thickness and helps to maximize the utilization of light energy and improve the photoelectric conversion efficiency of the battery. Since the top and the substrate of the perovskite solar cell need to share the same spectrum to capture the photon energy to the greatest extent, the ultra-thin first film layer has high light transmittance, which can enable the incident light to effectively penetrate into the substrate and further improve the photoelectric conversion efficiency of the battery. Moreover, the ultra-thin first film layer has the passivation effect at the interface and can serve as a chemical barrier to reduce the defects between the second film layer and the substrate, reduce non-radiative recombination, increase the carrier lifetime, and can also adjust the energy band structure, optimize the charge transport, reduce the energy level barrier, and promote the efficient separation and transport of charges. At the same time, within the above thickness range, in the preparation process, the first film layer can be deposited by methods such as PVD, ALD, evaporation, etc. These processes can prepare large-area uniform thin films and are suitable for the industrial preparation of large-size batteries. At the same time, these processes can control the thickness and quality of the oxide layer to ensure its compatibility with the functions of other film layers.

[0041] In some alternative embodiments, the N-type semiconductor material includes one or more materials selected from zinc oxide, titanium oxide, gallium nitride, tin oxide, indium gallium zinc oxide, fluorine-doped tin oxide, and fluorine-doped indium oxide.

[0042] Specifically, among N-type semiconductor materials, zinc oxide (ZnO) has a wide bandgap and high electron mobility, titanium oxide (TiO2) has a high dielectric constant and good stability, gallium nitride (GaN) has high electron mobility and chemical stability, tin oxide (SnO2) has good electron transport properties and transparency, indium gallium zinc oxide (IGZO) has high mobility and transparency. By doping fluorine into SnO2 to obtain fluorine-doped tin oxide (FTO), or doping fluorine into indium oxide to obtain fluorine-doped indium oxide (ITO), the conductivity and stability of the material can be further improved.

[0043] In some other alternative embodiments, the P-type semiconductor material includes one or more materials selected from nickel oxide, copper oxide, lead dioxide, polymer materials, metal halides, molybdenum sulfide, and cadmium selenide.

[0044] Specifically, nickel oxide (NiO), copper oxides (CuO, Cu2O), lead dioxide (PbO2), molybdenum sulfide (MoS2), copper oxide (CuO x ), cadmium selenide (CdSe) are all P-type semiconductor materials and can be used as hole transport layers in perovskite solar cells. Moreover, polymer materials such as poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and poly(triphenylamine methacrylate) (PTAA) and other polymer materials are also P-type hole transport materials. And metal halides such as lead halide perovskite, due to their good hole transport ability and transparency, can also be used as P-type semiconductor materials in perovskite solar cells.

[0045] Furthermore, when the above-mentioned ultra-thin oxide layer serves as the first film layer, the material selection should have N-type semiconductor characteristics, such as ZnO, TiO2, SnO2, etc. mentioned above. These materials can effectively reduce parasitic absorption while protecting the underlying ITO tunneling layer from contact with corrosive substances in the SAM layer, thereby improving the current density and long-term stability of the battery; the material selection should have P-type semiconductor materials. According to factors such as the energy band matching of the materials, the reduction of interface recombination loss, and the preparation process, parasitic absorption can be reduced. At the same time, through the synergistic effect of specific SAM materials and additives, the hole transport efficiency and the long-term stability of the battery can be further improved.

[0046] In some alternative embodiments, when the first film layer is an N-type semiconductor material, the first charge transport layer is an electron transport layer; when the first film layer is a P-type semiconductor material, the first charge transport layer is a hole transport layer.

[0047] Specifically, the first N-type film layer can serve as an electron transport layer. The second film layer has electron transport ability, and the first charge transport layer composed of the first film layer and the second film layer is an electron transport layer. The combination of the first film layer and the second film layer can reduce the interface defects between the perovskite absorption layer and the substrate. The first N-type film layer can passivate these defects and reduce non-radiative recombination, while the second film layer can further optimize the chemical bonding at the interface to form a more stable electron transport channel. The second film layer has electron transport ability, can adjust the energy band structure, and form a synergistic effect with the first N-type film layer to reduce the energy level barrier between the perovskite layer and the electron transport layer. Combining the low parasitic absorption of the ultra-thin first N-type film layer and the electron transport ability of the second film layer can improve the overall performance of the solar cell, including increasing the current density, voltage, and fill factor of the cell, thereby increasing the efficiency and stability of the cell.

[0048] In some alternative embodiments, the second film layer further includes additives, and the additives include amino functional groups and methylsilane functional groups.

[0049] Specifically, the additives in the second film layer require organic molecules with amino functional groups at one end and methylsilane functional groups at the other end. During the deposition process of the SAM solution, the phosphate groups in the SAM will form anchoring chemical bonds with the underlying oxide. The amino functional groups can interact with the phosphate groups in the SAM layer through hydrogen bonds and thus be fixed around the SAM layer. When the top-layer perovskite is prepared, the hydrogen bond between the additive and the SAM is broken. At this time, the methylsilane in the additive forms a covalent bond with the oxide of the underlying first film layer, increasing the modification effect on the oxide of the first film layer. This chemical modification can adjust the energy band structure, improve the interfacial properties between the perovskite absorption layer and the SAM layer, and between the SAM layer and the oxide layer, optimize charge transport, reduce the energy level barrier, and increase the separation and migration efficiency of charges. Moreover, the methylsilyl group can form more stable chemical bonds with the oxide layer of the first film layer, preventing the possible corrosive chemical groups in the SAM material from directly contacting the oxide layer (such as ITO), protecting the interface from chemical corrosion, and thus improving the chemical stability and long-term reliability of the device. In addition, such additives can enhance the charge transport ability of the second film layer, whether it is electrons or holes, and reduce the interface recombination loss.

[0050] In some alternative embodiments, as Figures 1 to 2 shown, the perovskite absorption layer 30 includes a third film layer 31 and a fourth film layer 32 arranged in a stacked manner. The fourth film layer 32 is located on the side of the third film layer 31 away from the second film layer 22. The material of the third film layer 31 includes a two-dimensional perovskite material, and the material of the fourth film layer 32 includes a three-dimensional perovskite material, wherein the two-dimensional perovskite material is formed by the reaction of amino functional groups with the three-dimensional perovskite material.

[0051] Specifically, the amino functional groups in the additive can react with the inorganic components in the perovskite layer to form a 2D perovskite structure. This 2D perovskite structure, namely the third film layer, can act as an interfacial passivation layer located between the three-dimensional perovskite layer and the second film layer. It can effectively passivate the defects on the surface and in the bulk of the material, reduce the non-radiative recombination rate, thereby increasing the carrier lifetime and the photoelectric conversion efficiency of the battery. 2D perovskites generally have better chemical and thermal stability than 3D perovskites. The layered structures of 2D perovskites and 3D perovskites can block the erosion of environmental factors such as moisture and oxygen on the perovskite layer, extending the service life and stability of the device. Among them, the 2D perovskite layer can act as a barrier to reduce the migration of ions in the perovskite material, especially ions such as lead (Pb) and methylammonium (MA), which helps to maintain the structural integrity and stability of the perovskite thin film and prevent performance degradation caused by ion migration.

[0052] According to another aspect of the present application, a method for preparing a perovskite solar cell is provided, as Figure 3 shown, including:

[0053] Step S201: Provide a substrate;

[0054] Step S202: Sequentially form a stacked first film layer, a second film layer, a perovskite absorption layer, a second charge transport layer, and a first electrode on the substrate. Among them, the first film layer and the second film layer constitute the first charge transport layer. The second film layer is located on the layer of the first film layer facing away from the substrate. The first film layer includes an N-type semiconductor material, and the second film layer includes a self-assembled monolayer material and an additive. The first charge transport layer and the second charge transport layer have different semiconductor materials.

[0055] Using the above method for preparing a perovskite solar cell of the present application, a first charge transport layer including a first film layer and a second film layer is formed on the substrate. The first film layer in the first charge transport layer can include an N-type semiconductor material or a P-type semiconductor material. When the first film layer is N-type, it is used for electron transport and can match the n-type layer in the substrate as the electron transport layer (ETL) of the perovskite battery to facilitate the transfer of electrons from the perovskite layer to the silicon bottom cell. Moreover, the second film layer includes a self-assembled monolayer material, which can increase the current density of the substrate. At the same time, the first film layer can passivate the interfacial defects between the perovskite and the second film layer, reduce non-radiative recombination, improve the charge collection efficiency, and extend the life of the battery. The first film layer can also act as a protective layer to prevent the corrosive chemical substances in the second film layer from directly contacting the substrate material, avoid interfacial corrosion, and enhance the long-term stability of the battery. In addition, by preparing appropriate oxide materials through processes such as PVD, ALD, and evaporation coating, the energy level barrier at the interface can be effectively reduced, further enhancing the charge transport efficiency. At the same time, large-area uniform thin films can be prepared, which is suitable for the industrial preparation of large-size batteries.

[0056] Exemplary embodiments of the method for preparing a perovskite solar cell provided according to the present application will be described in more detail below with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many different forms and should be construed as being limited only to the embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concept of these exemplary embodiments to those of ordinary skill in the art.

[0057] First, step S201 is performed: providing a substrate.

[0058] Exemplarily, the substrate may include a glass substrate. Specifically, the glass substrate may include FTO conductive glass, ITO conductive glass, AZO conductive glass, and a conductive flexible substrate. Another exemplarily, the substrate may also include a solar crystalline silicon substrate of an HTJ bottom cell. Specifically, the silicon substrate includes: a bottom TCO film layer and a first hydrogenated amorphous silicon layer, a first intrinsic hydrogenated amorphous silicon layer, a single crystal silicon layer, a second intrinsic hydrogenated amorphous silicon layer, and a second hydrogenated amorphous silicon layer that are sequentially stacked and formed on a first surface of the bottom TCO film layer perpendicular to the first surface. The surface of the second hydrogenated amorphous silicon layer facing away from the bottom TCO film layer is the bottom cell, that is, the front surface of the substrate. The solar bottom cell may also include a second electrode formed on the back surface of the bottom TCO film layer.

[0059] In a perovskite tandem solar cell structure, a tunneling layer is formed on the crystalline silicon substrate. The material of the tunneling layer includes but is not limited to one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide doped (In2O3:H), aluminum-doped zinc oxide (AZO), zirconium-doped indium oxide (IZrO), and zinc-doped tin oxide (ZTO), which effectively recombines electrons and holes with minimal resistance loss and ensures high optical transparency in the long wavelength band.

[0060] In other embodiments, the substrate may also include a Topcon bottom cell, an IBC bottom cell, and an ABC bottom cell. The preparation methods of the above bottom cells are the same as those in the prior art and will not be elaborated in this application one by one.

[0061] After providing the substrate, step S202 is performed: sequentially forming a stacked first film layer, a second film layer, a perovskite absorption layer, a second charge transport layer, and a first electrode on the substrate. Among them, the first film layer includes an N-type semiconductor material. In other embodiments, the first film layer may also include a P-type semiconductor material, and the second film layer includes a self-assembled monolayer material.

[0062] Specifically, the above step S202 may include the following steps:

[0063] First, perform step S2021: form a first film layer on a substrate, where the first film layer includes an N-type semiconductor material or a P-type semiconductor material.

[0064] Specifically, the above N-type semiconductor materials include one or more of zinc oxide, titanium oxide, gallium nitride, tin oxide, indium gallium zinc oxide, fluorine-doped tin oxide, and fluorine-doped indium oxide; the P-type semiconductor materials include one or more of nickel oxide, copper oxide, lead dioxide, polymer materials, metal halides, molybdenum sulfide, and cadmium selenide.

[0065] In some alternative embodiments, the process for forming the first film layer includes one or more of physical vapor deposition, atomic layer deposition, and evaporation coating processes, which can effectively reduce the energy level barrier at the interface, further enhance the charge transport efficiency, and at the same time, can prepare a large-area uniform thin film, suitable for the compatibility of the large-scale preparation process of large-size batteries, and facilitate industrial production.

[0066] Among them, the thickness of the first film layer is 1 to 10 nm, and the specific thickness is not limited in this application.

[0067] Then, perform step S2022: form a second film layer on the first film layer, and the second film layer includes self-assembled monolayer materials.

[0068] Specifically, if the first film layer is an N-type semiconductor material and the second film layer has the ability to transport electrons, then the first charge transport layer is an electron transport layer; if the first film layer is a P-type semiconductor material and the second film layer has the ability to transport holes, the first charge transport layer is a hole transport layer. The thickness of the second film layer is 1 to 2 nm, and the thickness of the second film layer is less than that of the first film layer, which helps to reduce costs and facilitate large-scale production while improving the photoelectric efficiency of the solar cell.

[0069] In some alternative embodiments, the material of the second film layer further includes additives, where the additives include amino functional groups and methylsilane functional groups.

[0070] Specifically, the process for forming the second film layer includes one of coating process, doctor blade coating process, spraying process, inkjet process, and chain machine deposition process. During the deposition of the SAM solution, the phosphate group in the SAM will form an anchoring chemical bond with the underlying oxide, and at the same time, form a hydrogen bond with the amino group in the additive, fixing the additive around the SAM layer. When the top-layer perovskite is prepared, the hydrogen bond between the additive and the SAM is broken, and the methylsilane in the additive forms a covalent bond with the underlying oxide, increasing the modification effect on the oxide.

[0071] Then, perform step S2023: form a perovskite absorption layer on the second film layer.

[0072] Specifically, the steps of forming the perovskite absorption layer include: First, a three-dimensional perovskite material layer is formed on the second film layer to form a fourth film layer, and the second film layer includes a self-assembled monolayer material and an additive; Then, the additive reacts with the three-dimensional perovskite material layer to generate a two-dimensional perovskite layer to form a third film layer, and the amino functional group reacts with the three-dimensional perovskite material to generate the perovskite absorption layer.

[0073] Then, step S2024 is performed: a second charge transport layer is formed on the perovskite absorption layer.

[0074] Specifically, the material of the second charge transport layer has a different semiconductor material from that of the first charge transport layer. For example, if the material of the first film layer is an N-type semiconductor material, that is, the first charge transport layer is an electron transport layer, then the material of the second charge transport layer is a P-type semiconductor material, and the second charge transport layer is a hole transport layer; if the material of the first film layer is a P-type semiconductor material, that is, the first charge transport layer is a hole transport layer, then the material of the second charge transport layer is an N-type semiconductor material, and the second charge transport layer is an electron transport layer.

[0075] Among them, the processes for forming the second charge transport layer include but are not limited to process methods such as PVD, ALD, evaporation, etc., and the present application does not make specific limitations.

[0076] In some alternative embodiments, after step S2024, step S2025 is further included: a buffer layer is formed on the second charge transport layer.

[0077] Specifically, a buffer layer is formed on the electron transport layer by a deposition process. The material of the buffer layer 80 has the same semiconductor material as that of the second charge transport layer to adjust the energy levels between the top cell and the bottom cell, reduce the energy loss and recombination loss at the interface, and can also passivate the surface defects of the second charge transport layer, reduce non-radiative recombination, and improve the carrier lifetime and cell efficiency.

[0078] In some alternative embodiments, after step S2025, step S2026 is further included: a transparent conductive layer is formed on the buffer layer.

[0079] Specifically, the processes for forming the buffer layer and the second charge transport layer include but are not limited to physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). Among them, physical vapor deposition (PVD) includes but is not limited to magnetron sputtering process, reactive sputtering process, DC sputtering process, AC sputtering process, vacuum coating process, arc evaporation process, and chemical vapor deposition (CVD) includes but is not limited to plasma-enhanced chemical vapor deposition (PECVD), metal-organic chemical vapor deposition (MOCVD), laser-induced chemical vapor deposition (LCVD). Those skilled in the art can make reasonable selections according to actual needs, and the present application does not make specific limitations.

[0080] Among them, the materials of the transparent conductive layer include, but are not limited to, one or more of indium zinc oxide (IZO), indium tin oxide (ITO), indium hydroxide doped (In2O3:H), aluminum-doped zinc oxide (AZO), indium zirconium oxide (IZrO), and zinc-doped tin oxide (ZTO), so as to effectively transfer electrons and allow light to penetrate into the perovskite layer, while playing a role in protecting the perovskite layer from being eroded or damaged by the external environment.

[0081] Then, step S2027 is carried out: forming a first electrode on the transparent conductive layer.

[0082] Specifically, the materials of the first electrode include, but are not limited to, a combination of one or more of Au, Ag, Cu, and Al, and this application does not make specific limitations. The process for forming the first electrode includes, but is not limited to, screen printing, thermal evaporation, and magnetron sputtering processes.

[0083] Hereinafter, the perovskite solar cell and its preparation method provided by this application will be further described in conjunction with examples and comparative examples.

[0084] Example 1

[0085] This example provides a preparation method of a perovskite solar cell, including:

[0086] Step S11: Providing a substrate, the substrate is a crystalline silicon bottom cell, and has an ITO tunneling layer on one side of the substrate;

[0087] Step S12: Cleaning the substrate, and forming a tin oxide layer on the ITO tunneling layer by using a reactive plasma deposition (RPD) process to form a first film layer, and the thickness of the first film layer is 5 nm;

[0088] Step S13: Depositing and forming a PFATs layer containing an additive 1,3-bis(diphenylphosphino)propane (DPPP) on the first film layer by using a coating process to form a second film layer, and the thickness of the second film layer is 2 nm, wherein the additive 1,3-bis(diphenylphosphino)propane (DPPP) does not include amino functional groups and methylsilane functional groups;

[0089] Step S14: Depositing a three-dimensional perovskite material layer on the second film layer by using a slot coating process to form a perovskite absorption layer, and the thickness of the perovskite absorption layer is 600 nm;

[0090] Step S15: Forming a nickel oxide layer on the perovskite absorption layer by using a physical vapor deposition (PVD) process to form a second charge transport layer, and the thickness of the second charge transport layer is 20 nm;

[0091] Step S16: Deposit an IZO layer on the buffer layer by PVD process to form a transparent conductive layer, and the thickness of the transparent conductive layer is 30 nm;

[0092] Step S17: Form an Ag layer on the transparent conductive layer by screen printing deposition process to form the first electrode.

[0093] Example 2

[0094] This example provides a preparation method of a perovskite solar cell, and the difference from Example 1 is:

[0095] Step S13: Deposit a PFATs layer containing the additive p - hydroxybenzylamine on the first film layer by coating process to form a second film layer, the thickness of the second film layer is 2 nm, and the additive p - hydroxybenzylamine includes an amino functional group and a methylsilane functional group;

[0096] Step S14: Deposit a three - dimensional perovskite material layer on the second film layer by slot - die coating process to form a fourth film layer. Among them, the amino functional group in the additive p - hydroxybenzylamine reacts with the three - dimensional perovskite material to generate a two - dimensional perovskite material layer to form a third film layer, and the third film layer and the fourth film layer constitute the perovskite absorption layer.

[0097] Example 3

[0098] This example provides a preparation method of a perovskite solar cell, and the difference from Example 2 is:

[0099] Step S12: Clean the substrate, and form a tin oxide layer on the ITO tunneling layer by reactive plasma deposition (RPD) process to form a first film layer, and the thickness of the first film layer is 20 nm.

[0100] Example 4

[0101] This example provides a preparation method of a perovskite solar cell, and the difference from Example 2 is:

[0102] Step S12: Clean the substrate, and form a tin oxide layer on the ITO tunneling layer by reactive plasma deposition (RPD) process to form a first film layer, and the thickness of the first film layer is 1 nm.

[0103] Example 5

[0104] This example provides a preparation method of a perovskite solar cell, and the difference from Example 2 is:

[0105] Step S12: Clean the substrate, and form a tin oxide layer on the ITO tunneling layer by reactive plasma deposition (RPD) process to form a first film layer, and the thickness of the first film layer is 10 nm.

[0106] Example 6

[0107] This example provides a method for preparing a perovskite solar cell, which is different from Example 2 in that:

[0108] Step S13: Deposit a PFATs layer containing the additive p - hydroxybenzylamine on the first film layer by a coating process to form a second film layer with a thickness of 15 nm. The additive includes an amino functional group and a methylsilane functional group.

[0109] Example 7

[0110] This example provides a method for preparing a perovskite solar cell, including:

[0111] Step S21: Provide a substrate, which is a crystalline silicon bottom cell, and has an ITO tunneling layer on one side of the substrate;

[0112] Step S22: Clean the substrate and form a nickel oxide layer on the ITO tunneling layer by physical vapor deposition to form a first film layer with a thickness of 5 nm;

[0113] Step S23: Deposit a 2PACz layer containing an additive on the first film layer by a coating process to form a second film layer with a thickness of 2 nm. The additive includes an amino functional group and a methylsilane functional group;

[0114] Step S24: Deposit a three - dimensional perovskite material layer on the first film layer by a slot - die coating process to form a fourth film layer. Among them, the amino functional group in the additive reacts with the three - dimensional perovskite material to generate a two - dimensional perovskite material layer, thereby forming a third film layer. The third film layer and the fourth film layer constitute a perovskite absorption layer with a thickness of 600 nm;

[0115] Step S25: Form a C 60 , to form a second charge transport layer with a thickness of 20 nm;

[0116] Step S26: Form a tin oxide layer on the second charge transport layer by ALD to form a buffer layer with a thickness of 20 nm;

[0117] Step S27: Deposit an IZO layer on the buffer layer by PVD to form a transparent conductive layer with a thickness of 30 nm;

[0118] Step S28: Form an Ag layer on the transparent conductive layer by screen - printing deposition to form a first electrode.

[0119] Comparative Example 1

[0120] This comparative example provides a method for preparing a perovskite solar cell, which is different from Example 2 in that:

[0121] Step S13: A PFATs layer is deposited on the first film layer by a coating process to form a second film layer with a thickness of 2 nm;

[0122] Step S14: A three-dimensional perovskite material layer is deposited on the second film layer by a vapor deposition process to form a perovskite absorption layer with a thickness of 600 nm.

[0123] Comparative Example 2

[0124] This comparative example provides a method for preparing a perovskite solar cell, which is different from Example 7 in that:

[0125] Step S22: The substrate is cleaned, and a nickel oxide layer is formed on the ITO tunneling layer by a physical vapor deposition process to form a first film layer with a thickness of 5 nm;

[0126] Step S23: A 2PACz layer is deposited on the first film layer by a coating process to form a second film layer with a thickness of 2 nm;

[0127] Step S24: A three-dimensional perovskite material layer is deposited on the second film layer by a vapor deposition process to form a perovskite absorption layer with a thickness of 600 nm.

[0128] The perovskite solar cells provided in the examples and comparative examples are respectively irradiated with a spectral distribution of AM1.5G and a light intensity of 1000 mW / cm 2 of an AAA solar simulator as the light source. All devices are not encapsulated, and the optoelectronic properties of the solar cells are measured in an atmospheric environment. Among them, the effective area of the device is 1.0 cm 2 . The J-V curve is obtained by measuring with a Keithly2400 digital source meter, and then the optoelectronic property test parameters are obtained. The results are shown in Table 1.

[0129] Table 1

[0130] Voc (V) <![CDATA[Jsc (mA / cm 2 )]]> FF (%) Eff (%) Example 1 1.90 19.22 78.17 28.55 Example 2 1.94 19.80 81.33 31.24 Example 3 1.93 19.18 79.88 29.00 Example 4 1.94 19.87 80.46 31.02 Example 5 1.92 20.05 80.12 30.84 Example 6 1.93 19.63 80.42 30.47 Example 7 1.97 19.20 80.85 30.58 Comparative Example 1 1.89 19.26 77.46 28.20 Comparative Example 2 1.94 19.23 79.24 29.64

[0131] As can be seen from the results in Table 1, compared with Comparative Example 1, in Examples 1 to 6, since the second film layer in the N-type charge transport layer includes an additive, the open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, and conversion efficiency EFF are all significantly improved, indicating that including an additive in the second film layer of the N-type charge transport layer can improve the photoelectric conversion efficiency of the solar cell; compared with Comparative Example 2, in Example 7, since the self-assembled monolayer in the P-type charge transport layer includes an additive, the open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, and conversion efficiency EFF are all improved, indicating that including an additive in the self-assembled monolayer of the P-type charge transport layer can also improve the photoelectric conversion efficiency of the solar cell.

[0132] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the element.

[0133] The above are only the embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A perovskite solar cell, characterized in that: It includes a substrate, a first charge transport layer, a perovskite absorption layer, a second charge transport layer and a first electrode which are stacked in sequence, wherein the first charge transport layer includes a first film layer and a second film layer which are stacked, the second film layer is located at a layer of the first film layer away from the substrate, the first film layer includes an N-type semiconductor material, the second film layer includes a self-assembled monomolecular material and an additive, and the first charge transport layer and the second charge transport layer have different semiconductor materials.

2. The perovskite solar cell according to claim 1, characterized in that The thickness of the second film layer in a stacking direction is less than or equal to the thickness of the first film layer in the stacking direction, wherein the stacking direction is a direction from the substrate to the first electrode.

3. The perovskite solar cell according to claim 1, characterized in that The thickness of the first film layer in the stacking direction is 1-10 nm.

4. The perovskite solar cell according to claim 1, characterized in that: The N-type semiconductor material includes one or more materials selected from the group consisting of zinc oxide, titanium oxide, gallium nitride, tin oxide, indium gallium zinc oxide, fluorine-doped tin oxide, and fluorine-doped indium oxide.

5. The perovskite solar cell according to claim 1, characterized in that: The first film layer is the N-type semiconductor material, and the first charge transport layer is an electron transport layer.

6. The perovskite solar cell according to any one of claims 1 to 5, characterized in that: The additive includes an amino functional group and a methylsilane functional group.

7. The perovskite solar cell according to claim 6, characterized in that: The perovskite absorption includes a third film layer and a fourth film layer which are stacked, the fourth film layer is located on the side of the third film layer away from the second film layer, the material of the third film layer includes a two-dimensional perovskite material, and the material of the fourth film layer includes a three-dimensional perovskite material, wherein the two-dimensional perovskite material is generated by the reaction of the amino functional group and the three-dimensional perovskite material.

8. A method for preparing a perovskite solar cell, characterized in that: include: providing a substrate; A first film layer, a second film layer, a perovskite absorption layer, a second charge transport layer and a first electrode are sequentially formed on the substrate, wherein the first film layer and the second film layer constitute the first charge transport layer, the second film layer is located at a layer of the first film layer away from the substrate, the first film layer includes an N-type semiconductor material, the second film layer includes a self-assembled monomolecular material and an additive, and the first charge transport layer and the second charge transport layer have different semiconductor materials.

9. The preparation method according to claim 8, characterized in that: The process for forming the first film layer includes one or more of physical vapor deposition, atomic layer deposition and evaporation processes, and the thickness of the first film layer is 1 to 10 nm; the process for forming the second film layer includes one of a coating process, a scraping process, a spraying process, an inkjet process and a chain machine deposition process, and the second film layer includes a self-assembled monomolecular material.

10. The preparation method according to claim 8, characterized in that: The steps of forming the perovskite absorption layer include: Generating a three-dimensional perovskite material layer on the second film layer to form a fourth film layer, wherein the second film layer includes a self-assembled monomolecular material and an additive; The additive reacts with the three-dimensional perovskite material layer to generate a two-dimensional perovskite layer to form a third film layer, and the third film layer and the fourth film layer constitute the perovskite absorption layer.

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