Perovskite thin film, perovskite solar cell and preparation method

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a perovskite thin film, a perovskite solar cell and a preparation method thereof. The perovskite thin film is prepared by adopting a two-step method, and the method sequentially comprises the steps of preparing an inorganic frame layer, treating the inorganic frame layer by a solvent, applying organic salt to the inorganic frame layer and the like. On the premise of not damaging the inorganic frame layer, the reaction between the inorganic frame layer and the organic salt is effectively improved, the quality of the finally prepared perovskite thin film is improved, and the application range is wide.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaics, and specifically relates to perovskite thin films, perovskite solar cells, and preparation methods thereof. Background Art

[0002] Organic-inorganic metal halide perovskite solar cells have excellent optoelectronic properties and potential low-cost manufacturing characteristics, and are a highly promising type of solar cell. In addition, the bandgap of perovskite materials can be adjusted, and a tandem solar cell can be formed by stacking the perovskite material itself or other photovoltaic materials, thereby obtaining a higher photoelectric conversion efficiency.

[0003] At present, there are two commonly used methods for preparing the perovskite layer, namely the one-step method and the two-step method. In the one-step method, the raw materials are directly dissolved in a solution, and a film is directly formed in one step by methods such as spin coating, slot die coating, and blade coating. In the two-step method, the raw materials are divided into two types. First, an inorganic salt mainly composed of lead iodide is deposited on a substrate to form an inorganic framework layer, and then an organic salt mainly composed of methylammonium iodide or formamidinium iodide is deposited on the surface of the inorganic framework layer, and then the perovskite layer is obtained through the reaction between the two.

[0004] The thin film prepared by the one-step method generally has high film performance, but can only produce a thin film with a flat surface, which is more friendly for single-junction perovskite solar cells. However, when applied to the tandem of perovskite and crystalline silicon, if the texture of the silicon bottom cell is large, the perovskite cannot conformally grow on the texture of the crystalline silicon. In the two-step method, the deposition in the first step can be to dissolve the inorganic salt in a solution and prepare it on the substrate surface, or to deposit the inorganic salt thin film on the substrate surface by evaporation, and the deposition of the organic salt in the second step can also be deposited by evaporation or solution methods. Therefore, this method can prepare a tandem cell in which the perovskite conformally grows on the texture of the crystalline silicon. In addition, an environmentally friendly solvent can be used in the second step of this method, but the perovskite thin film prepared by this method generally has lower quality than that prepared by the one-step method.

[0005] In the existing two-step method, when the inorganic framework layer is prepared by a solution method, a conformally growing thin film cannot be prepared; when the inorganic framework layer is prepared by an evaporation method, although a conformally growing thin film can be obtained, the quality of the finally prepared thin film is poor. Therefore, improving the performance of the perovskite thin film prepared by the two-step method is of great significance for the application of the two-step method. Summary of the Invention

[0006] To solve the problems existing in the prior art, after the inorganic framework layer is prepared in the present invention, the inorganic framework layer is treated with a solvent, so that the originally relatively dense structure of the inorganic framework layer is destroyed by the solvent, which is beneficial to the reaction between the organic salt and the inorganic framework layer to generate a high-quality perovskite thin film. Specifically, the present invention provides a method for preparing a perovskite thin film, and the method includes:

[0007] (1) Prepare an inorganic framework layer;

[0008] (2) Coat a solvent on the surface of the inorganic framework layer, and then anneal to obtain a modified inorganic framework layer;

[0009] (3) Apply an organic salt to the modified inorganic framework layer, and then anneal to obtain the perovskite thin film.

[0010] In one or more embodiments, the solvent in step (2) is a first solvent.

[0011] In one or more embodiments, the solvent in step (2) comprises a first solvent and a second solvent with a volume ratio of 1000:1 - 10:1.

[0012] In one or more embodiments, the first solvent is one or more selected from alcohol solvents and non - alcohol organic solvents in which lead iodide is poorly soluble or insoluble.

[0013] In one or more embodiments, the second solvent is a solvent in which lead iodide is readily soluble or slightly soluble.

[0014] In one or more embodiments, the alcohol solvent is one or more selected from isopropyl alcohol, n - butyl alcohol, and ethanol.

[0015] In one or more embodiments, the non - alcohol organic solvents in which lead iodide is poorly soluble or insoluble are one or more selected from acetone, tetrahydrofuran, ether, ethyl acetate, and toluene.

[0016] In one or more embodiments, the second solvent is one or more selected from N,N - dimethylformamide, dimethyl sulfoxide, 1,3 - dimethyl - 3,4,5,6 - tetrahydro - 2 - pyrimidinone (DMPU), N - methylpyrrolidone, dimethylacetamide, γ - butyrolactone (GBL), acetonitrile, tetramethylsilane, propylene carbonate, ethylene carbonate, and water.

[0017] In one or more embodiments, in step (1), the inorganic framework layer is prepared by a solution coating method or an evaporation deposition method.

[0018] In one or more embodiments, in step (3), the organic salt is applied to the modified inorganic framework layer by a solution coating method or an evaporation deposition method.

[0019] In one or more embodiments, in step (1), the thickness of the inorganic framework layer is 100 - 1000 nm.

[0020] In one or more embodiments, in step (1), a solution containing an inorganic salt is coated on a substrate to obtain the inorganic framework layer.

[0021] In one or more embodiments, in step (1), the inorganic salts are evaporated so that the inorganic salts are deposited on the substrate to obtain the inorganic framework layer.

[0022] In one or more embodiments, in step (1), when preparing the inorganic framework layer, an annealing process is adopted, the annealing temperature is 50 - 200 °C, and the annealing time is 1 - 100 min.

[0023] In one or more embodiments, in step (1), the inorganic framework layer comprises an inorganic salt with the molecular formula BX2, where the B ion is one or more selected from lead ions, tin ions, copper ions, zinc ions, gallium ions, and calcium ions, and the X ion is selected from F - , I - , Br - , Cl - and SCN - and one or more of the above.

[0024] In one or more embodiments, in step (2), the solvent is coated on the surface of the inorganic framework layer so that the solvent completely covers the surface of the inorganic framework layer.

[0025] In one or more embodiments, in step (2), the coating method is one or more of spin coating, blade coating, slot die coating, or inkjet printing.

[0026] In one or more embodiments, in step (2), the annealing is one-step annealing or multi-step annealing.

[0027] In one or more embodiments, in step (2), the annealing method is one or more of hot plate annealing, infrared annealing, or vacuum annealing.

[0028] In one or more embodiments, in step (2), the annealing temperature is 90 - 200 °C, and the annealing time is 1 - 100 min.

[0029] In one or more embodiments, in step (3), a solution containing an organic salt is coated on the modified inorganic framework layer, thereby applying the organic salt into the modified inorganic framework layer.

[0030] In one or more embodiments, in step (3), the organic salt is evaporated so that the organic salt is deposited on the modified inorganic framework layer, thereby applying the organic salt into the modified inorganic framework layer.

[0031] In one or more embodiments, in step (3), the annealing is one-step annealing or multi-step annealing.

[0032] In one or more embodiments, in step (3), the annealing method is one or more of hot plate annealing, infrared annealing, or vacuum annealing.

[0033] In one or more embodiments, in step (3), the annealing temperature is 50 - 180 °C, and the annealing time is 1 - 100 min.

[0034] In one or more embodiments, in step (3), the molecular formula of the organic salt is AX, the A ion is one or more selected from methylammonium ion, formamidinium ion, cesium ion, and rubidium ion, and the X ion is one or more selected from F - 、I - 、Br - 、Cl - and SCN - and one or more of them.

[0035] In one or more embodiments, in step (3), the perovskite film comprises a perovskite structure substance with the chemical formula ABX3, the A ion is one or more selected from methylammonium ion, formamidinium ion, cesium ion, and rubidium ion, the B ion is one or more selected from lead ion, tin ion, copper ion, zinc ion, gallium ion, and calcium ion, and the X ion is one or more selected from F - 、I - 、Br - 、Cl - and SCN - and one or more of them.

[0036] In one or more embodiments, in step (3), the thickness of the perovskite film is 100 - 1500 nm.

[0037] Another aspect of the present invention provides a perovskite film prepared by using the method described in any one of the embodiments of the present invention.

[0038] Another aspect of the present invention further provides a perovskite solar cell comprising the perovskite film described in any one of the embodiments of the present invention.

[0039] In one or more embodiments, the perovskite solar cell is a single - junction perovskite cell, a crystalline silicon - perovskite tandem cell, a perovskite - perovskite tandem cell, a perovskite - copper indium gallium selenide tandem cell, a perovskite - gallium arsenide tandem cell, an organic - perovskite tandem cell, a flexible perovskite cell, or a flexible tandem cell containing perovskite.

[0040] The technical solution of the present invention provides a new implementation means for preparing high-quality perovskite thin films by a two-step method, which can improve the quality of the finally prepared perovskite thin films without damaging the inorganic framework layer; its application scope is also relatively wide, and it can not only be applied in the two-step preparation of non-conformal growth, but also play a role in the conformal growth thin films prepared by the two-step method, with strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagrams of the structures of normal perovskite solar cells in some embodiments.

[0042] Figure 2 Schematic diagrams of the structures of inverted perovskite solar cells in some embodiments.

[0043] Figure 3 Schematic diagrams of the structures of perovskite / crystalline silicon tandem solar cells in some embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] To enable those skilled in the art to understand the features and effects of the present invention, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0045] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0046] As used herein, the terms "comprising", "including", "containing" and similar terms encompass the meanings of "consisting essentially of" and "consisting of". For example, when it is disclosed herein that "A comprises B and C", it should be considered that "A consists essentially of B and C" and "A consists of B and C" have been disclosed herein.

[0047] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0048] In this article, unless otherwise specified, the percentage refers to the mass percentage and the ratio refers to the mass ratio.

[0049] In this text, when describing embodiments or examples, it should be understood that it is not used to limit the present invention to these embodiments or examples. On the contrary, all alternatives, improvements, and equivalents of the methods and materials described in the present invention can be covered within the scope defined by the claims.

[0050] In this text, for the sake of brevity of description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered to be within the scope described in this specification.

[0051] In the present invention, the evaporation method (also known as the evaporation deposition method) refers to heating at a high temperature to evaporate the raw material, and then depositing it on the surface of the substrate.

[0052] In the present invention, the solvent method (also known as the solution coating method) refers to dissolving the raw material in a solvent, and then depositing it on the surface of the substrate.

[0053] The present invention provides a method for preparing a perovskite thin film to improve the device performance. The preparation method of the present invention includes:

[0054] (1) Prepare an inorganic framework layer;

[0055] (2) Coat the solvent on the surface of the inorganic framework layer, and then anneal to obtain a modified inorganic framework layer;

[0056] (3) Apply an organic salt to the modified inorganic framework layer, and then anneal to obtain the perovskite thin film.

[0057] After the inorganic framework layer is prepared, the method of the present invention uses a solvent to treat the inorganic framework layer, so that the originally relatively dense structure of the inorganic framework layer is destroyed by the solvent, which is beneficial to the reaction of the organic salt with the inorganic framework layer to generate perovskite, and is beneficial to the formation of a high-quality perovskite thin film.

[0058] In step (1), the thickness of the inorganic framework layer is 100 - 1000 nm, such as 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm.

[0059] In step (1), when preparing the inorganic framework layer, the annealing process can be increased to improve the repeatability of the device.

[0060] In step (1), the annealing temperature is 50 - 200 °C, such as 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C; the annealing time is 1 - 100 min, such as 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min, 48 min, 50 min, 52 min, 54 min, 56 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min, 82 min, 84 min, 86 min, 88 min, 90 min, 92 min, 94 min, 96 min, 98 min.

[0061] In step (2), the solvent is coated on the surface of the inorganic framework layer such that the solvent completely covers the surface of the inorganic framework layer. For cost considerations, the amount of the solvent relative to the inorganic framework layer is just enough to cover the inorganic framework layer.

[0062] The solvent in step (2) can be a first solvent, or include a first solvent and a second solvent. In some embodiments, the solvent in step (2) consists of a first solvent and a second solvent.

[0063] The first solvent is one or more selected from alcohol solvents and non - alcohol organic solvents in which lead iodide is poorly soluble or insoluble. The alcohol solvents are preferably isopropyl alcohol, n - butyl alcohol or ethanol. Examples of non - alcohol organic solvents in which lead iodide is poorly soluble or insoluble include acetone, tetrahydrofuran, diethyl ether, ethyl acetate and toluene.

[0064] The second solvent is a solvent in which lead iodide is highly soluble or slightly soluble. Examples of solvents in which lead iodide is highly soluble or slightly soluble include N,N - dimethylformamide, dimethyl sulfoxide, 1,3 - dimethyl - 3,4,5,6 - tetrahydro - 2 - pyrimidinone (DMPU), N - methylpyrrolidone, dimethylacetamide, γ - butyrolactone (GBL), acetonitrile, tetramethylsilane, propylene carbonate, ethylene carbonate and water.

[0065] In step (2), the volume ratio of the first solvent to the second solvent is preferably 1000:1 - 10:1, such as 900:1, 800:1, 700:1, 600:1, 500:1, 400:1, 300:1, 200:1, 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1.

[0066] The present invention discovers that treating the inorganic framework layer with the aforementioned first solvent or a mixed solvent formed by mixing the aforementioned first solvent and the second solvent in a specific ratio can effectively loosen the originally relatively dense structure of the inorganic framework layer, which is beneficial to the reaction of the organic salt with the inorganic framework layer to generate a high-quality perovskite film and is beneficial to improving the performance of the photovoltaic device.

[0067] In step (2), the annealing temperature is 90 - 200 °C, such as 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, 170 °C, 175 °C, 180 °C, 185 °C, 190 °C, 195 °C; the annealing time is 1 - 100 min, such as 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min, 48 min, 50 min, 52 min, 54 min, 56 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min, 82 min, 84 min, 86 min, 88 min, 90 min, 92 min, 94 min, 96 min, 98 min.

[0068] In step (3), the annealing temperature is 50 - 180°C, such as 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C; the annealing time is 1 - 100 min, such as 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min, 48 min, 50 min, 52 min, 54 min, 56 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, 72 min, 74 min, 76 min, 78 min, 80 min, 82 min, 84 min, 86 min, 88 min, 90 min, 92 min, 94 min, 96 min, 98 min.

[0069] The thickness of the perovskite thin film is 100 - 1500 nm, such as 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm.

[0070] In the present invention, the annealing process is one-step annealing or multi-step annealing, preferably two-step annealing. The specific annealing method can be one or more of hot plate annealing, infrared annealing or vacuum annealing.

[0071] The inorganic framework layer of the present invention refers to a compound mainly composed of inorganic salts of divalent cations and monovalent anions, and other inorganic salts or organic salts are allowed to be included, such as CsBr, CsI, FAI or BAI (n-butylamine hydroiodide), etc. can be included.

[0072] The organic salt of the present invention refers to a compound mainly composed of monovalent organic cations and monovalent anions, and other organic salts or a small amount of inorganic salts can also be included, such as BAI, PDADI (1,3-diaminopropane dihydroiodide) or RbCl, etc. can be included.

[0073] In the present invention, the chemical formula of the perovskite structure substance is ABX3; the A ion can be selected from methylammonium ion (MA + ) and formamidinium ion (FA +) one or more of acetamidine ions, cesium ions, and rubidium ions; B ions can be one or more selected from lead ions, tin ions, copper ions, zinc ions, gallium ions, and calcium ions; X ions can be selected from F - , I - , Br - , Cl - , BF4 - , and SCN - one or more of them.

[0074] The perovskite solar cells of the present invention are generally divided into normal and inverted perovskite solar cells according to the positions of the hole transport layer and the electron transport layer, and their schematic structures are respectively as Figure 1 and Figure 2 shown, where HTL represents the hole transport layer and ETL represents the electron transport layer. Specifically, the perovskite solar cells of the present invention can be normal single-junction perovskite solar cells, inverted single-junction perovskite solar cells, normal tandem perovskite solar cells, or inverted tandem perovskite solar cells. In some embodiments, the perovskite solar cells of the present invention are perovskite crystalline silicon tandem solar cells, and their schematic structure is as Figure 3 shown.

[0075] In the present invention, the normal single-junction perovskite solar cell can sequentially include a conductive substrate, an electron transport layer, a perovskite thin film, a hole transport layer, and a back electrode. In the present invention, the inverted single-junction perovskite solar cell can sequentially include a conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, and a back electrode. In the present invention, the normal tandem perovskite solar cell can sequentially include a bottom electrode, a bottom cell, a tunneling layer, a normal perovskite top cell, and a top electrode, and the positive top cell can sequentially include an electron transport layer, a perovskite thin film, and a hole transport layer. In the present invention, the inverted tandem perovskite solar cell can sequentially include a bottom electrode, a bottom cell, a tunneling layer, an inverted perovskite top cell, and a top electrode, and the inverted top cell can sequentially include a hole transport layer, a perovskite thin film, and an electron transport layer.

[0076] In the present invention, the conductive substrate can be a flexible substrate or a rigid steel core, and the rigid substrate can be selected from indium tin oxide (ITO) transparent conductive glass, fluorine-doped tin oxide (FTO) transparent conductive glass, tungsten-doped indium oxide (IWO) transparent conductive glass, and aluminum-doped zinc oxide (AZO) transparent conductive glass.

[0077] In the present invention, the hole transport layer can be a self-assembled molecule (SAM) and / or NiOx; the self-assembled molecule is selected from one or more of [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACZ), (2-(9H-carbazol-9-yl)ethyl)phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), [4-(9H-carbazol-9-yl)butyl]phosphonic acid, and [4-(7H-dibenzocarbazol-7-yl)butyl]phosphoric acid.

[0078] The method for preparing a normal single-junction perovskite solar cell in the present invention includes:

[0079] (1) Depositing an electron transport layer on the surface of a conductive substrate;

[0080] (2) Depositing a perovskite thin film on the surface of the electron transport layer;

[0081] (3) Depositing a hole transport layer on the surface of the perovskite thin film;

[0082] (4) Depositing a back electrode on the surface of the hole transport layer to obtain a normal single-junction perovskite solar cell.

[0083] The method for preparing a tandem single-junction perovskite solar cell in the present invention includes:

[0084] (1) Depositing a hole transport layer on the surface of a conductive substrate;

[0085] (2) Depositing a perovskite thin film on the surface of the hole transport layer;

[0086] (3) Depositing an electron transport layer on the surface of the perovskite thin film;

[0087] (4) Depositing a back electrode on the surface of the electron transport layer to obtain a tandem single-junction perovskite solar cell.

[0088] The method for preparing a normal tandem perovskite solar cell in the present invention includes:

[0089] (1) Depositing a bottom electrode and a tunneling layer on both sides of the bottom cell respectively;

[0090] (2) Depositing an electron transport layer on the surface of the tunneling layer;

[0091] (3) Depositing a perovskite thin film on the surface of the electron transport layer;

[0092] (4) Depositing a hole transport layer on the surface of the perovskite thin film;

[0093] (5) Depositing a top electrode on the surface of the hole transport layer to obtain a normal tandem perovskite solar cell.

[0094] The method for preparing a tandem perovskite solar cell of the present invention includes:

[0095] (1) Depositing a bottom electrode and a tunneling layer on both sides of the bottom cell respectively;

[0096] (2) Depositing a hole transport layer on the surface of the tunneling layer;

[0097] (3) Depositing a perovskite thin film on the surface of the hole transport layer;

[0098] (4) Depositing an electron transport layer on the surface of the perovskite thin film;

[0099] (5) Depositing a top electrode on the surface of the electron transport layer to obtain a tandem perovskite solar cell.

[0100] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the embodiments are conventional methods, reagents and materials in the art unless otherwise specified. The starting compounds in the embodiments can be obtained through commercial channels.

[0101] Example 1

[0102] As Figure 2 shown, a wide-bandgap perovskite solar cell is prepared in the order of a conductive substrate, a hole transport layer, self-assembled monolayers (SAMs), a perovskite light-absorbing layer, an electron transport layer and a back electrode. The specific steps are as follows:

[0103] (1) Pretreatment of the conductive substrate: Provide ITO conductive glass with a size of 2.5 cm * 2.5 cm. After cleaning and drying, it is cleaned in an ultraviolet ozone cleaner for 20 min to obtain a clean conductive substrate;

[0104] (2) Preparation of the hole transport layer: SAMs are deposited on the substrate by spin coating in a nitrogen glove box: 140 μL of an ethanol solution of [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz) at 0.5 mg / mL is covered on the substrate for 30 s, spin-coated at a speed of 4000 r.p.m. for 10 s, then annealed at 100 °C for 10 min, subsequently washed once with ethanol, and annealed at 100 °C for 5 min to obtain a hole transport layer with a thickness of 1 nm;

[0105] (3) Preparation of the perovskite layer:

[0106] Select 150 μL of a DMF:DMSO = 97:3 (v / v) mixed solution containing 1.3 mol / L of PbI2 and 0.13 mol / L of CsBr (the molar ratio of PbI2 to CsBr is 10:1). In a glove box, use a spin coater to drop the above mixed solution onto the hole transport layer, spin at a speed of 3000 r.p.m. for 30 s, and then anneal at 120 °C for 10 min to obtain an inorganic framework layer;

[0107] Subsequently, treat the inorganic framework layer with 200 μL of a mixed solvent (isopropyl alcohol (IPA): dimethyl sulfoxide (DMSO) = 97:3). In a glove box, use a spin coater to drop the above mixed solvent onto the inorganic framework layer, and then quickly spin coat at a speed of 4000 r.p.m. for 30 s, and then anneal at 100 °C for 5 min;

[0108] Prepare an organic salt layer on the substrate by the solution method and react to form a perovskite active layer: Select an IPA solution containing 60 mg / mL of FAI, 50 mg / mL of FABr, and 7 mg / mL of MACl. After dropping 300 μL of the above IPA solution onto the inorganic framework layer, quickly spin coat at a speed of 4000 r.p.m. for 30 s, and then anneal at 90 °C for 5 min. Subsequently, take it out of the glove box and anneal at 150 °C for 20 min in air with a humidity of 20 - 40% RH to obtain a perovskite light-absorbing layer with a thickness of 600 nm;

[0109] Take 80 μL of an IPA solution of 0.5 mg / mL of 1,3 - propanediamine hydroiodide and drop it on the surface of the perovskite light-absorbing layer. Spin coat at a speed of 4000 r.p.m. for 30 s in a nitrogen glove box, and then anneal on a hot plate at 100 °C for 2 min to obtain a perovskite passivation layer with a thickness of 2 nm;

[0110] The perovskite light-absorbing layer and the perovskite passivation layer together form the perovskite layer;

[0111] (4) Prepare the electron transport layer: Sequentially evaporate a C60 layer with a thickness of 30 nm and a BCP layer with a thickness of 6 nm on the perovskite passivation layer by thermal evaporation. The C60 layer and the BCP layer together form an electron transport layer with a thickness of 36 nm;

[0112] (5) Prepare the back electrode: Evaporate Ag with a thickness of 200 nm on the electron transport layer by thermal evaporation to obtain the back electrode, and obtain a perovskite solar cell module. The effective area of a single cell is 0.07 cm 2 。

[0113] Example 2

[0114] This example prepares a solar cell module similar to that of Example 1, but the differences are as follows:

[0115] When preparing the perovskite layer by a two-step method in step (3):

[0116] The inorganic framework layer is prepared by evaporation: Lead iodide and cesium bromide (the rate ratio is The overall film thickness is 280 nm) are deposited by vacuum thermal evaporation. After deposition, annealing is carried out at 150 °C for 2 min in a nitrogen atmosphere;

[0117] The organic salt layer is prepared as follows: Select 300 μL of an IPA solution containing 0.28 mol / L of methyl ether hydroiodide, 0.28 mol / L of methyl ether hydrobromide, 0.07 mol / L of methylammonium thiocyanate, and 0.07 mol / L of methylammonium hydrochloride. After dropping this IPA solution on the inorganic framework layer, it is rapidly spin-coated at a speed of 4000 r.p.m. for 30 s, then annealed at 90 °C for 3 min, and then taken out of the glove box and annealed at 150 °C for 20 min in air with a humidity of 20 - 40% RH to obtain a perovskite light-absorbing layer with a thickness of 420 nm.

[0118] Example 3

[0119] In this example, a solar cell module similar to that in Example 1 is prepared, but the differences are as follows:

[0120] When preparing the perovskite layer by a two-step method in step (3):

[0121] The inorganic framework layer is prepared by evaporation: Lead iodide, cesium bromide, and lead chloride (the rate ratio is The overall film thickness is 290 nm) are deposited by vacuum thermal evaporation. After deposition, annealing is carried out at 150 °C for 2 min in a nitrogen atmosphere;

[0122] The organic salt layer is prepared by evaporation: The organic salt FAI is evaporated by vacuum thermal evaporation, and an organic salt layer with a thickness of 160 nm is deposited on the inorganic framework layer. After deposition, first anneal at 150 °C for 10 min in a nitrogen atmosphere, and then anneal at 150 °C for 20 min in air with a humidity of 30 - 50% RH to obtain a perovskite light-absorbing layer with a thickness of 440 nm.

[0123] Example 4

[0124] As Figure 3 shown, a tandem perovskite / crystalline silicon solar cell is prepared in the order of the bottom cell, hole transport layer, perovskite light-absorbing layer, electron transport layer, and back electrode. The specific steps are as follows:

[0125] (1) Prepare the bottom cell:

[0126] Select an n-type silicon wafer with a grain size less than 1 μm and a thickness of 300 μm. Using the plasma-enhanced chemical vapor deposition (PECVD) process, deposit intrinsic amorphous silicon layers (a-Si:H(i)) on both sides of the silicon wafer;

[0127] Using the PECVD process, deposit an a-Si:H(p) layer on the surface of the intrinsic amorphous silicon layer on the back side of the silicon wafer to obtain a hole transport layer with a thickness of 20 nm;

[0128] Using the PECVD process, deposit an a-Si:H(n) layer on the surface of the intrinsic amorphous silicon layer on the front side of the silicon wafer to obtain an electron transport layer with a thickness of 25 nm;

[0129] Furthermore, obtain a bottom cell with a total thickness of 300 μm;

[0130] (2) Prepare the back electrode: Use magnetron sputtering to deposit indium tin oxide (ITO) on the surface of the hole transport layer of the bottom cell to obtain a transparent electrode layer with a thickness of 8 nm; then use thermal evaporation to deposit silver on the surface of the transparent electrode layer to obtain a silver grid line electrode with a thickness of 400 nm. The transparent electrode layer and the silver grid line electrode together form the back electrode;

[0131] (3) Prepare the hole transport layer: Dissolve [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACZ) in ethanol to prepare a MeO-4PACZ solution with a concentration of 0.5 mg / mL. Take 140 μL of the MeO-4PACZ solution and drop it on the surface of the electron transport layer of the bottom cell, then spin-coat it at a speed of 4000 rpm for 10 s, and after the spin-coating is completed, transfer it to a heating plate at 100 °C and anneal it for 10 min, and then anneal it on a heating plate at 100 °C for 5 min to obtain a hole transport layer with a thickness of 1 nm;

[0132] (4) Prepare the perovskite layer: First deposit lead iodide and cesium bromide (the rate ratio is The overall film thickness is 530 nm) by vacuum thermal evaporation. After the deposition is completed, anneal it in a nitrogen atmosphere at 150 °C for 2 min;

[0133] Subsequently, use 200 μL of a mixed solvent (IPA:DMSO = 97:3) to treat the inorganic framework layer. In a glove box, use a spin coater to drop the mixed solution on the inorganic framework layer, and then quickly spin-coat it at a speed of 4000 r.p.m for 30 s, and then anneal it at 100 °C for 5 min;

[0134] Select an IPA solution containing 0.35 mol / L methyl ether hydroiodide, 0.35 mol / L methyl ether hydrobromide, 0.09 mol / L methylammonium thiocyanate, and 0.09 mol / L methylammonium hydrochloride. After dropping 300 μL of the above IPA solution onto the inorganic framework layer, spin-coat it rapidly at a speed of 4000 r.p.m. for 60 s, then anneal it at 90 °C for 3 min. Subsequently, take it out of the glove box and anneal it at 150 °C for 20 min in air with a humidity of 20 - 40% RH to obtain a perovskite light-absorbing layer with a thickness of 800 nm;

[0135] Take 80 μL of an IPA solution of 0.5 mg / mL 1,3-propanediamine hydroiodide and drop it on the surface of the perovskite light-absorbing layer. Spin-coat it at a speed of 4000 r.p.m. for 30 s in a nitrogen glove box, and then anneal it on a hot plate at 100 °C for 2 min to obtain a perovskite passivation layer with a thickness of 2 nm;

[0136] The perovskite light-absorbing layer and the perovskite passivation layer together form the perovskite layer;

[0137] (5) Prepare the electron transport layer: Evaporate graphene (C60) on the perovskite passivation layer by thermal evaporation to obtain an electron transport layer with a thickness of 12 nm;

[0138] (6) Prepare the buffer layer: Deposit tin dioxide (SnO2) on the surface of the electron transport layer by atomic layer deposition (ALD) to obtain a buffer layer with a thickness of 15 nm;

[0139] (7) Prepare the top electrode: Deposit IZO on the surface of the buffer layer by magnetron sputtering to obtain a transparent conductive layer with a thickness of 50 nm; Deposit MgF2 on the surface of the transparent electrode layer by thermal evaporation to obtain a full-area MgF2 antireflection layer with a thickness of 100 nm; Deposit silver on the top by thermal evaporation to obtain a silver grid line electrode with a thickness of 400 nm; The transparent conductive layer, the antireflection layer, and the silver electrode together form the top electrode, and at the same time, a reverse perovskite crystalline silicon tandem solar cell is obtained.

[0140] Example 5

[0141] This example prepares a solar cell module similar to that in Example 4, but the differences are as follows:

[0142] When preparing the perovskite layer by the two-step method in step (4):

[0143] The inorganic framework layer is prepared by evaporation: First deposit lead iodide, cesium bromide, and lead chloride (the rate ratio is The overall film thickness is 460 nm) by vacuum thermal evaporation. After the deposition is completed, anneal it at 150 °C for 2 min in a nitrogen atmosphere;

[0144] The organic salt layer is prepared by the evaporation method: The organic salt FAI is evaporated by the vacuum thermal evaporation method, and an organic salt layer with a thickness of 260 nm is deposited on the inorganic framework layer. After the deposition is completed, it is first annealed at 150 °C for 10 min in a nitrogen atmosphere, and then annealed at 150 °C for 20 min in air with 30 - 50% RH to obtain a perovskite light-absorbing layer with a thickness of 690 nm.

[0145] Example 6

[0146] A solar cell module similar to that in Example 1 is prepared in this example, but the differences are as follows:

[0147] When preparing the perovskite layer in step (3):

[0148] The inorganic framework layer is treated with 200 μL of a mixed solvent (n-butanol: N-methylpyrrolidone = 95:5). In the glove box, using a spin coater, the above mixed solvent is dropped on the inorganic framework layer, and then quickly spin-coated at a speed of 4000 r.p.m. for 30 s, and then annealed at 100 °C for 5 min.

[0149] Example 7

[0150] A solar cell module similar to that in Example 1 is prepared in this example, but the differences are as follows:

[0151] When preparing the perovskite layer in step (3):

[0152] The inorganic framework layer is treated with 200 μL of isopropanol. In the glove box, using a spin coater, the above isopropanol is dropped on the inorganic framework layer, and then quickly spin-coated at a speed of 4000 r.p.m. for 30 s, and then annealed at 100 °C for 5 min.

[0153] Example 8

[0154] A solar cell module similar to that in Example 4 is prepared in this example, but the differences are as follows:

[0155] When preparing the perovskite layer in step (4):

[0156] The inorganic framework layer is treated with 200 μL of a mixed solvent (IPA: DMF = 98:2). In the glove box, using a spin coater, the above mixed solvent is dropped on the inorganic framework layer, and then quickly spin-coated at a speed of 4000 r.p.m. for 30 s, and then annealed at 100 °C for 5 min.

[0157] Comparative Example 1

[0158] Other conditions of this comparative example are the same as those of Example 1, except that when preparing the perovskite layer, the inorganic framework layer is not treated with a mixed solution of IPA:DMSO = 97:3, and the organic salt layer is directly introduced to react to produce the perovskite layer.

[0159] Comparative Example 2

[0160] Other conditions of this comparative example are the same as those of Example 2, except that when preparing the perovskite layer, the inorganic framework layer is not treated with a mixed solution of IPA:DMSO = 97:3, and the organic salt layer is directly introduced to react to produce the perovskite layer.

[0161] Comparative Example 3

[0162] Other conditions of this comparative example are the same as those of Example 3, except that when preparing the perovskite layer, the inorganic framework layer is not treated with a mixed solution of IPA:DMSO = 97:3, and the organic salt layer is directly introduced to react to produce the perovskite layer.

[0163] Comparative Example 4

[0164] Other conditions of this comparative example are the same as those of Example 4, except that when preparing the perovskite layer, the inorganic framework layer is not treated with a mixed solution of IPA:DMSO = 97:3, and the organic salt layer is directly introduced to react to produce the perovskite layer.

[0165] Comparative Example 5

[0166] Other conditions of this comparative example are the same as those of Example 5, except that when preparing the perovskite layer, the inorganic framework layer is not treated with a mixed solution of IPA:DMSO = 97:3, and the organic salt layer is directly introduced to react to produce the perovskite layer.

[0167] Test Example

[0168] At 25 °C, under the standard solar spectrum of AM 1.5G and a light intensity of 100 mW / cm 2 ², using a solar simulator, the voltage range was set to -0.05 - 2 V, and the performance (open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency) of the solar cell modules in Examples 1 - 8 and Comparative Examples 1 - 5 was measured. The specific results are shown in Table 1.

[0169] (1) Open-circuit voltage (Voc): The voltage value corresponding to zero current.

[0170] (2) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current magnitude per unit cell surface area is the short-circuit current density.

[0171] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the battery to the product of the open-circuit voltage and the short-circuit current, calculated as (Pmax / Voc*Isc), where the maximum power point is the point at which the battery output power reaches its maximum value.

[0172] (4) Photovoltaic conversion efficiency (PCE): The photovoltaic conversion efficiency refers to the ratio of the maximum output power to the incident light power (Pin), calculated as (Pmax / Pin)*100%.

[0173] Table 1: Photovoltaic performance test results of the solar cell modules of Examples 1-8 and Comparative Examples 1-5

[0174]

[0175] From the experimental results in Table 1, it can be seen that the solar cell modules prepared by the method of the present invention (introducing a solvent treatment step in the two-step method) have better cell performance compared to the solar cell modules prepared without solvent treatment, indicating that the preparation method of the present invention can effectively improve cell performance such as the open-circuit voltage, fill factor, and photovoltaic conversion efficiency of the cell.

Claims

1. A method for preparing a perovskite film, characterized in that: The method comprises: (1) preparing an inorganic framework layer; (2) coating a solvent onto the surface of the inorganic framework layer, and then annealing to obtain a modified inorganic framework layer; (3) applying an organic salt to the modified inorganic framework layer, followed by annealing to obtain the perovskite film.

2. The method according to claim 1, characterized in that The solvent in step (2) is the first solvent, or the solvent in step (2) includes the first solvent and the second solvent in a volume ratio of 1000:1-10:1; The first solvent is one or more selected from alcohol solvents and non-alcohol organic solvents in which lead iodide is poorly soluble or insoluble; The second solvent is a solvent in which lead iodide is easily soluble or slightly soluble.

3. The method according to claim 2, characterized in that The alcohol solvent is one or more selected from isopropanol, n-butanol and ethanol; The non-alcohol organic solvent in which lead iodide is poorly soluble or insoluble is one or more selected from acetone, tetrahydrofuran, ether, ethyl acetate and toluene; The second solvent is one or more selected from N,N-dimethylformamide, dimethyl sulfoxide, 1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidone, N-methylpyrrolidone, dimethylacetamide, γ-butyrolactone, acetonitrile, tetramethylsilane, propylene carbonate, ethylene carbonate and water.

4. The method according to claim 1, characterized in that In step (1), the inorganic framework layer is prepared by solution coating or evaporation deposition; in step (3), the organic salt is applied to the modified inorganic framework layer by solution coating or evaporation deposition.

5. The method according to claim 1, characterized in that Step (1) has one or more of the following characteristics: The thickness of the inorganic framework layer is 100-1000nm; Applying a solution containing an inorganic salt onto a substrate, and optionally annealing the solution to obtain the inorganic framework layer; Alternatively, the inorganic salt is evaporated to deposit the inorganic salt on the substrate, and optionally annealed to obtain the inorganic framework layer; In the annealing process for preparing the inorganic framework layer, the annealing temperature is 50-200° C. and the annealing time is 1-100 min. The inorganic framework layer comprises an inorganic salt with a molecular formula of BX2, wherein the B ions are selected from one or more of lead ions, tin ions, copper ions, zinc ions, gallium ions and calcium ions, and the X ions are selected from F-, I - Br - , Cl - and SCN - One or more of .

6. The method according to claim 1, characterized in that Step (2) has one or more of the following characteristics: Applying a solvent to the surface of the inorganic framework layer so that the solvent completely covers the surface of the inorganic framework layer; The coating method is one or more of spin coating, blade coating, slit coating or inkjet printing; Annealing is one-step annealing or multi-step annealing; The annealing method is one or more of heating table annealing, infrared annealing or vacuum annealing; The annealing temperature is 90-200° C., and the annealing time is 1-100 min.

7. The method according to claim 1, characterized in that Step (3) has one or more of the following characteristics: Applying a solution containing an organic salt onto the modified inorganic framework layer, thereby applying the organic salt into the modified inorganic framework layer; or evaporating the organic salt and depositing the organic salt onto the modified inorganic framework layer, thereby applying the organic salt into the modified inorganic framework layer; Annealing is one-step annealing or multi-step annealing; The annealing method is one or more of heating table annealing, infrared annealing or vacuum annealing; The annealing temperature is 50-180°C, and the annealing time is 1-100min; The molecular formula of the organic salt is AX, the A ion is one or more selected from methylamine ion, formamidine ion, cesium ion and rubidium ion, and the X ion is one or more selected from F - ,I - Br - , Cl - and SCN - One or more of; The perovskite film comprises a perovskite structure material with a chemical formula of ABX3, wherein the A ions are one or more selected from methylamine ions, formamidine ions, cesium ions and rubidium ions, the B ions are one or more selected from lead ions, tin ions, copper ions, zinc ions, gallium ions and calcium ions, and the X ions are one or more selected from F - ,I - Br - , Cl - and SCN - One or more of; The thickness of the perovskite film is 100-1500nm.

8. A perovskite film prepared by the method according to any one of claims 1 to 7.

9. A perovskite solar cell comprising the perovskite thin film according to claim 8.

10. The perovskite solar cell according to claim 9, characterized in that: The perovskite solar cell is a single-junction perovskite cell, a crystalline silicon-perovskite tandem cell, a perovskite-perovskite tandem cell, a perovskite-copper indium gallium selenide tandem cell, a perovskite-gallium arsenide tandem cell, an organic-perovskite tandem cell, a flexible perovskite cell or a flexible tandem cell containing perovskite.

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