Perovskite precursor solution for preparing flexible photovoltaic module and application thereof

Abstract

The invention discloses a perovskite precursor solution for preparing a flexible photovoltaic module and application thereof, and belongs to the technical field of solar cells. The technical problems to be solved are that a perovskite precursor prepared from a perovskite precursor solution cannot be arranged in order, so that a grain boundary has defects, and a prepared perovskite film cannot be industrially produced in air and is poor in stability. The key point of the technical scheme is that a perovskite precursor solution prepared by adopting a specific solvent combination and proportion and a perovskite material is moderate in volatilization rate, uniform film formation is facilitated, and the coffee ring effect or pinhole defect caused by rapid drying is avoided. The controllable crystallization rate provides enough time to enable the perovskite precursor to be arranged in order, and the grain boundary defect is reduced, so that the performance of the subsequently prepared flexible photovoltaic module is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a perovskite precursor solution for preparing flexible photovoltaic modules and its application. Background Technology

[0002] For understanding the technical content of this invention: With the rapid development of the Internet of Things (IoT), smart homes, and wearable devices, indoor low-light photovoltaics (IPV) has emerged as a new direction in the renewable energy field. This technology utilizes indoor light sources (LEDs, fluorescent lamps, etc., 100-1000 lux) to power low-power electronic devices, offering advantages such as battery-free operation, self-powered operation, and sustainability. Due to its unique band structure and stability, it shows great potential in the field of indoor photovoltaics (IPV). Indoor low-light photovoltaics can be deposited at temperatures below 150°C, making them suitable for PET / PEN flexible substrates and meeting the needs of wearable electronics and smart homes. With collaborative innovation in materials, processes, and applications, indoor photovoltaics is expected to usher in a "battery-free electronics era" and become an important component of the green energy revolution.

[0003] Perovskite has been widely studied recently as a promising absorber layer material for solar cells due to its low cost and high efficiency. The advantages of perovskite materials include: (1) organic-inorganic hybrid perovskite is a direct bandgap semiconductor material with an ideal bandgap width (-1.55 eV), exhibiting excellent absorption capabilities throughout the visible light range; (2) perovskite materials have high carrier mobility and long diffusion distance; (3) they simultaneously possess the ability to absorb photons and transport electrons and holes; (4) they can be prepared at low temperatures and are easy to form films, which is beneficial for the fabrication of flexible devices. However, because perovskite materials are sensitive to water and oxygen molecules and are easily degraded under environmental conditions, this hinders the commercialization of perovskite solar cells. Therefore, solving the long-term stability problem of perovskite solar cells has become a prerequisite for their commercialization.

[0004] Currently, the main strategy for improving the stability of perovskite materials is to replace some of the iodide ions in the perovskite composition with bromide ions. However, this indoor low-light photovoltaic system still faces key challenges such as halogen phase separation, solvent residue, and poor crystal quality when fabricated on a large scale in air, which severely restricts its commercialization process. Uneven Br / I distribution: Under indoor low light, the concentration of photogenerated carriers is low, and halogen ions migrate more easily, forming an inactive phase, leading to performance degradation. Under illumination, iodide and bromide ions in the perovskite aggregate and undergo phase separation. Phase separation leads to the formation of bromine-enriched and iodine-enriched regions, which become major traps for carriers, severely reducing the efficiency and phase stability of indoor photovoltaics. In addition, defects on the perovskite surface also cause severe non-radiative recombination of carriers, further reducing the efficiency of wide-bandgap perovskite solar cells under indoor conditions.

[0005] Previously, a mixed solvent of DMF and DMSO was mainly used as the solvent for perovskite precursor solutions. However, using this mixed solvent presents unique technical challenges, primarily stemming from issues such as Br / I ratio control, solvent residue, and phase separation. In low-light formulations, conventional DMSO exhibits strong hygroscopicity and a slow solvent evaporation rate. Prolonging the exposure of DMSO to moisture intensifies the hydration reaction, rapidly adsorbing water and forming a DMSO-H2O complex. This disrupts the coordination equilibrium between DMSO and PbI2, interferes with the exchange of FAI (formamidinium iodide) and PbI2 molecules, leading to disordered crystallization and the formation of impurity phases.

[0006] Currently, DMSO has been found to be a solvent for perovskite precursor solutions, but the stability of the prepared perovskite activated layer is not high. Therefore, the solvent was changed when preparing perovskite precursor solutions, and a mixture of multiple solvents was used for preparation.

[0007] Relevant patent documents retrieved: This document, published in China (CN105405973A) on March 16, 2016, discloses a mesoscopic solar cell based on perovskite-based light-absorbing materials. It includes a glass substrate, a transparent conductive layer, a hole-blocking layer, an electron transport layer, and a back electrode. The perovskite precursor solution uses two or more of the following solvents as a mixed solvent: N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), isopropanol (IPA), acetonitrile (ACN), butanone, acetic acid, acetic anhydride, and NEP (1-ethyl-2-pyrrolidone). The cell prepared using this method exhibits improved charge transport performance, resulting in significantly increased photoelectric conversion efficiency and improved long-term light-induced stability. However, it does not mention the improvement in the cell's photovoltaic performance.

[0008] This document, published in China (CN119486564A) on February 18, 2025, discloses a perovskite precursor solution, a perovskite solar cell, and a method for its preparation. The perovskite precursor solution comprises an organic solvent and additives, specifically a mixed solvent prepared from DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), GBL (γ-butyrolactone), and NMP (N-methyl-2-pyrrolidone), which is intended to improve the performance of subsequently fabricated devices. However, the perovskite precursor solution prepared using this method exhibits poor performance in subsequent solar cell fabrication, such as a low open-circuit current and low photoelectric conversion efficiency.

[0009] In solving the above problems or overcoming the above defects, the present invention encountered the following difficulties and obstacles: Therefore, it is urgent to improve the phase stability of perovskite materials and reduce the impact of surface defects on cell performance, thereby improving the efficiency of perovskite indoor photovoltaics. Summary of the Invention

[0010] The purpose of this invention is to provide: A perovskite precursor solution for preparing flexible photovoltaic modules and its application, as well as related technologies, are disclosed to solve technical problems such as the inability of perovskite precursors prepared from the perovskite precursor solution to arrange in an orderly manner, resulting in defects at grain boundaries, and the inability of the prepared perovskite thin film to be industrially produced in air and its poor stability, or a combination thereof.

[0011] Terminology Explanation: Unless otherwise defined, all technical terms in this document have the same meanings as commonly understood by one of ordinary skill in the art to which the subject matter of the claims pertains. Unless otherwise stated, all patents, patent inventions, and publications cited in this document are incorporated herein by reference in their entirety. If multiple definitions exist for terms in this document, the definitions in this chapter shall prevail.

[0012] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0013] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0014] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0015] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the weights mentioned in the embodiments of this application can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0016] Unless otherwise stated, conventional methods within the scope of the art, such as photovoltaic performance testing and scanning electron microscopy, shall be used.

[0017] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0018] The terms “optional / arbitrary” or “optionally / arbitrarily” mean that the event or situation described below may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0019] The term "perovskite precursor solution" as used in this article refers to a homogeneous solution formed by dissolving a perovskite material precursor in a solvent and adding a modifier, used to form a perovskite thin film on a substrate through a coating process. Essentially, it disperses the chemical components of perovskite in molecular or ionic form in a solvent, providing a "pre-formulation" for subsequent thin film crystallization.

[0020] As used herein, the term "slot coating" refers to a coating technique for applying solutions, slurries, or extruded films onto a flat substrate. This process involves dissolving or suspending the desired coating material in a precursor solution or slurry and delivering it to the substrate surface through a slot die. Controlled delivery of the coating liquid allows for the continuous production of wide coating materials on the substrate. By controlling the solution deposition rate and the relative velocity between the solution and the substrate, thin material coatings ranging from 10 nanometers to 100 micrometers in thickness can be obtained.

[0021] The term "VCD" used in this article refers to Vacuum Flash Drying, which is one of the key core equipment urgently needed for the industrialization of perovskite batteries. It can produce high-quality perovskite thin films by precisely controlling the evaporation rate and deposition thickness of perovskite materials.

[0022] The term "magnetron sputtering" as used in this article refers to a sputtering deposition method that uses a magnetic field to confine the movement of electrons near a target surface. In the magnetron sputtering process, two planar electrodes are placed in a vacuum chamber: the target material serves as the cathode, and the substrate as the anode. A permanent magnet is placed on the cathode side to form a ring-shaped magnetic field. After a small amount of argon gas is introduced, a DC high-voltage electric field is applied to induce a glow discharge in the gas. Argon positive ions bombard the cathode target, causing it to sputter. The sputtered neutral target atoms or molecules are deposited on the substrate to form a thin film.

[0023] The term "PET / ITO / NiOx / Me-4PACz" used in this article refers to: PET, polyethylene terephthalate, a common polymer material; ITO, indium tin oxide, a transparent conductive oxide; NiOx, nickel oxide, which can be used as a hole transport layer material in perovskite solar cells; and Me-4PACz, a self-assembling molecule, such as 2-(3,6-dimethoxy-9H-carbazole-9-yl)ethylphosphonic acid, which can form a strong coupling with NiOx to construct an integrated hole transport layer. PET / ITO / NiOx / Me-4PACz likely refers to a multilayer structure composed of these materials, commonly used in the fabrication of perovskite solar cells.

[0024] The term "substrate" as used in this article refers to the base material that serves as a support or starting layer during the material preparation or device manufacturing process. Other materials are usually deposited, grown, or coated on the substrate, such as glass and silicon wafers.

[0025] The term "conductive substrate" as used in this article refers to a substrate material with high electrical conductivity, such as doped silicon substrates and gallium arsenide substrates. Its conductivity is improved through specific doping processes, and it is often used in applications with high electrical performance requirements, such as semiconductor devices and solar cells.

[0026] The term "hole transport layer" used in this article refers to the layer located between the active layer and the anode, which promotes hole transport while suppressing reverse flow between holes and the cathode. It is one of the key components affecting the performance of solar cells. Commonly used hole transport layer materials include conductive polymers such as PEDOT:PSS.

[0027] The term "crystallization rate" used in this article refers to the speed at which the material crystallization process proceeds. It is expressed as the reciprocal of the time required for the crystallization process to proceed to the halfway point and is determined by the nucleation rate and the grain growth rate.

[0028] The term “film uniformity” as used in this article refers to the consistency of the properties of a film across the entire substrate. The most common measurement method is thickness uniformity, but it also includes the uniformity of other properties such as refractive index, density, or chemical composition.

[0029] The term "self-assembled monolayer" as used in this article refers to molecular assemblies that spontaneously form on a surface through adsorption of organic molecules. These molecules are organized into more or less ordered regions. Self-assembled monolayers typically consist of head groups, molecular chains, and terminal groups with specific functions. The head groups have a strong affinity for the substrate, which can anchor the molecules to the substrate.

[0030] The term "perovskite active layer" used in this article refers to the key functional layer in a perovskite solar cell that absorbs photons and generates electron-hole pairs. It is usually composed of materials with a perovskite structure, such as ABX3 type (A is an organic cation, B is a metal cation, and X is a halogen element) perovskite materials, and its performance directly affects the photoelectric conversion efficiency of the cell.

[0031] The term "electron transport layer" as used in this article refers to a layer of material located between the perovskite active layer and the cathode in a solar cell. Its main function is to collect and transport electrons generated in the perovskite active layer, while preventing holes from transporting to the cathode, so as to achieve effective separation and transport of electrons and holes and improve the photoelectric performance of the cell.

[0032] The term "metal top electrode" as used in this article refers to an important component of a solar cell, usually located at the top of the cell structure. It is generally made of a metal material with good conductivity and stability, such as silver or aluminum. Its function is to collect the current generated in the cell and lead the current out for external power supply.

[0033] The term "photovoltaic performance" used in this article refers to the ability and related characteristics of a solar cell to convert solar energy into electrical energy. It mainly includes parameters such as photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor. These parameters reflect the power generation capacity and performance of solar cells under different light conditions.

[0034] In a first aspect, the present invention provides: a perovskite precursor solution for preparing flexible photovoltaic modules, comprising a perovskite material and a solvent, wherein the perovskite material comprises cesium iodide (CsI), formamidinium iodide (FAI), lead bromide (PbBr2), and lead iodide (PbI2); the solvent is a mixture of a first solvent and a second solvent, wherein the first solvent is N,N-dimethylformamide (DMF), and the second solvent is selected from one or more of N-methylpyrrolidone (NMP), 1-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), tetrahydrofuran (THF), isopropanol (IPA), acetonitrile (ACN), and 2-methoxyethanol (2-ME); The volume ratio of the first solvent to the second solvent is 7-9:1-3; the additive is a mixture of potassium thiocyanate and rubidium thiocyanate; the concentration of the perovskite material in the perovskite precursor solution is 1M.

[0035] As a preferred embodiment, the volume ratio of the first solvent and the second solvent is selected from any value or range between 7-9:1-3; Preferably, the volume ratio of the first solvent and the second solvent is selected from any value or range between 7-9:1-3, specifically from: 7:1, 7:2, 7:3, 8:1, 8:2, 8:3, 8.4:1.6, 9:1, 9:2, 9:3 or any two of them; More preferably, the volume ratio of the first solvent and the second solvent is selected from any value or range between 7-9:1-3, specifically from: 7:3, 8:1, 8:2, 8.4:1.6, 9:1, 9:2 or any two of them; More preferably, the volume ratio of the first solvent and the second solvent is selected from any value or range between 7-9:1-3, specifically from: 7:3, 8:1, 8:2, 8.4:1.6, 9:1 or any two of them; More preferably, the volume ratio of the first solvent and the second solvent is selected from any value or range between 7-9:1-3, specifically from: 7:3, 8.4:1.6, 9:1 or any two of them; More preferably, the volume ratio of the first solvent to the second solvent is 8.4:1.6.

[0036] Preferably, the concentration of the perovskite material in the perovskite precursor solution is 1M.

[0037] Preferably, the additives are 2% potassium thiocyanate and 2% rubidium thiocyanate by weight percentage.

[0038] Preferably, the second solvent is at least two of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, and γ-butyrolactone.

[0039] In a preferred embodiment, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-190:10-190; Preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-150:10-150; More preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:10, 10:20, 10:30, 10:40, 10:80, 10:100, 10:130, 10:150, 10:10, 10:20, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20. 100:30, 100:40, 100:60, 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of these. More preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 60:10, 60:30, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20, 100:30, 100:40, 100 :60, 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of these. More preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 62.5:37.5, 60:40, 100:40, 100:60, 100:80, 140:120, 150:10, 150:20, 180:100, 187.5:112.5, 190:100 or any range between two of them; More preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:150, 62.5:37.5, 100:60, 150:10, 187.5:112.5 or any range between two of them; More preferably, the second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio of 100:60.

[0040] In a preferred embodiment, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone with a volume ratio selected from any value or range between 10-190:10-190; Preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150; More preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:10, 10:20, 10:30, 10:40, 10:80, 10:100, 10:130, 10:150, 10:10, 10:20, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20, 100 30, 100:40, 100:60, 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of these. More preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 60:10, 60:30, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20, 100:30, 100:40, 100:60. 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of these. More preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 62.5:37.5, 60:40, 100:40, 100:60, 100:80, 140:120, 150:10, 150:20, 180:100, 187.5:112.5, 190:100 or any range between two of them; More preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:150, 62.5:37.5, 100:60, 150:10, 187.5:112.5 or any range between two of them; More preferably, the second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 100:60.

[0041] In a preferred embodiment, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-190:10-190. Preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150; More preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:10, 10:20, 10:30, 10:40, 10:80, 10:100, 10:130, 10:150, 10:10, 10:20, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20, 1 00:30, 100:40, 100:60, 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of these. More preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 60:10, 60:30, 62.5:37.5, 60:40, 60:80, 60:100, 60:130, 60:150, 100:10, 100:20, 100:30, 100:40, 100:6 0, 100:80, 100:100, 100:130, 120:10, 100:20, 150:30, 100:40, 118:110, 130:120, 140:10, 140:50, 140:80, 140:100, 140:120, 150:10, 150:20, 180:60, 180:80, 180:100, 187.5:112.5, 190:100, or a range between any two of them; More preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:130, 10:150, 62.5:37.5, 60:40, 100:40, 100:60, 100:80, 140:120, 150:10, 150:20, 180:100, 187.5:112.5, 190:100 or any range between two of them; More preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 10-150:10-150, specifically selected from: 10:150, 62.5:37.5, 100:60, 150:10, 187.5:112.5 or any range between two of them; More preferably, the second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 100:60.

[0042] Secondly, the present invention provides the application of the above-mentioned perovskite precursor solution in the preparation of flexible indoor photovoltaic modules.

[0043] Thirdly, the present invention provides: a flexible indoor photovoltaic module, the module comprising the perovskite active layer, substrate, conductive substrate, hole transport layer, self-assembled monolayer, electron transport layer and metal top electrode prepared above.

[0044] Fourthly, the present invention provides a method for preparing the above-mentioned flexible indoor photovoltaic module, comprising the following steps: (1) Preparation of perovskite precursor solution: Dissolve perovskite material and additives in solvent, filter after preparation; (2) Preparation of perovskite active layer: The perovskite precursor solution prepared in step (1) is coated on the self-assembled monolayer film by slit coating method, and the perovskite active layer film is obtained after annealing.

[0045] As a preferred embodiment, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone with a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5; Preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone, and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:0.1:1.9, 7:1:0.1, 7:1:1, 7:0.5:1, 7:1.5:1, 7:1.875:1.125, 8:0.1: 0.5, 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1, 9:1:1.5, 9:1.5:1, 9:1.5:1.5, 9:1.9:1.9 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8.4:0.1:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8.4:0.1:1.5, 8.4:1:0.6, 8.4:1.5:0.1, 9:0.625:0.375 or any two of them; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio of 8.4:1:0.6.

[0046] As a preferred embodiment, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5; Preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone, and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:0.1:1.9, 7:1:0.1, 7:1:1, 7:0.5:1, 7:1.5:1, 7:1.875:1.125, 8:0.1:0.5 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1, 9:1:1.5, 9:1.5:1, 9:1.5:1.5, 9:1.9:1.9, or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any range between two of them; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8.4:0.1:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8.4:0.1:1.5, 8.4:1:0.6, 8.4:1.5:0.1, 9:0.625:0.375 or any two of them; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 8.4:1:0.6.

[0047] As a preferred embodiment, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5; Preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone, and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:0.1:1.9, 7:1:0.1, 7:1:1, 7:0.5:1, 7:1.5:1, 7:1.875:1.125, 8:0.1:0. 5, 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1, 9:1:1.5, 9:1.5:1, 9:1.5:1.5, 9:1.9:1.9 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8:0.1:1, 8.4:0.1:1.5, 8.4:0.5:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.875:1.125, 8:0.1:0.5, 8.4:0.1:1.5, 8.4:1:0.5, 8.4:1:0.6, 8.4:1:1, 8.4:1:1.5, 8.4:1.5:0.1, 9:0.625:0.375, 9:1:1 or any two of these ranges; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio selected from any value or range between 7-9:0.1-1.9:0.1-1.5, specifically selected from: 7:1.9:0.1, 8:1.4:0.6, 9:0.1:1.9 or any two of them; More preferably, the solvent in step (1) is a mixture of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 8.4:1:0.6.

[0048] Preferably, the annealing in step (2) is a two-step annealing method, wherein the first step is low-temperature pre-annealing and the second step is high-temperature annealing.

[0049] Preferably, the low-temperature pre-annealing is carried out in an infrared light wave furnace.

[0050] Preferably, the low-temperature pre-annealing temperature is 100°C and the time is 10 minutes.

[0051] Preferably, the high-temperature annealing is performed on a hot bench.

[0052] Preferably, the high-temperature annealing temperature is 150°C and the time is 20 minutes.

[0053] As the optimal implementation method, the preparation method includes the following steps: (1) Preparation of perovskite precursor solution: Dissolve perovskite material and additives in a solvent, wherein the solvent is a mixed solution of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a mass ratio of 8:1.4:0.6. After preparation, filter and set aside. (2) Preparation of perovskite active layer: Slit coating step (1) The perovskite precursor solution prepared is used to prepare a wide-bandgap perovskite active layer. The specific parameters are set as follows: coating speed 12mm / s, gap height 150um, liquid injection speed 28μL / s, VCD: 10s to 10Pa, 10Pa pressure held for 40s; immediately transfer to infrared light wave furnace for low-temperature pre-annealing. The first stage of pre-annealing temperature is 100℃ and the pre-annealing time is 10min. In the second stage, the perovskite film is placed face down on the heating plate to ensure that the distance between the film and the heating plate is 5cm; then high-temperature annealing is performed at 150℃ for 20min to obtain the perovskite active layer film.

[0054] Based on further solutions to the technical problems of the present invention, or simultaneous solutions to multiple technical problems, the preferred solution in the technical solution provided in the first aspect of the present invention includes: The first preferred solution is a perovskite precursor solution for preparing flexible photovoltaic modules. This solution not only solves the technical problem of "the perovskite precursor not being able to arrange itself in an orderly manner, resulting in defects at grain boundaries," but also further solves the technical problem of "not being able to be industrially produced in air."

[0055] Embodiments 1-15 of this invention at least support the protection scope of claim 1.

[0056] Regarding claim 1: the type of the second solvent and the volume ratio of the first solvent and the second solvent. The technical feature “the second solvent is selected from one or more of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol” is summarized from the common feature “type of second solvent” by the corresponding technical feature in the foregoing explanation and / or Examples 1-15, which states that the second solvent is one or more combinations of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol. Therefore, those skilled in the art can reasonably presume that the technical feature "the second solvent is selected from one or more of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol", its subordinate concepts and their substantially equivalent technical means, and technical means that can replace "the second solvent is selected from one or more of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol" based on existing technology and conventional technical means and common knowledge, should all fall within the protection scope of claim 1. For example, if other technical features remain unchanged, replacing "the second solvent is selected from one or more of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol" with a combination of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, and 2-methoxyethanol, etc., still falls within the protection scope of claim 1 of this invention.

[0057] The technical feature "the volume ratio of the first solvent to the second solvent is 1-9:1-3" is derived from the corresponding technical features in the foregoing explanation and / or Examples 1-15, such as the volume ratio of the first solvent to the second solvent being 8.4:1.6, 9:1, 7:3, etc., summarized by the common feature "the combination and proportion of solvents". Therefore, those skilled in the art can reasonably infer that the technical feature "the volume ratio of the first solvent to the second solvent is 1-9:1-3", its subordinate concepts and their substantially equivalent technical means, and technical means that can replace "the volume ratio of the first solvent to the second solvent is 1-9:1-3" based on the existing level of technology and conventional technical means and common knowledge, should all fall within the protection scope of claim 1. For example, replacing "the volume ratio of the first solvent to the second solvent is 1-9:1-3" with a volume ratio of 1:1.5, etc., while keeping other technical features unchanged, still falls within the protection scope of claim 1 of this invention.

[0058] In this invention, embodiments 1-3 and 10-11 at least support the protection scope of claim 3.

[0059] Regarding claim 3: the second solvent combination and its proportions The technical feature “the second solvent combination and its ratio is 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” is summarized from the common feature “the combination and ratio of solvents” in the foregoing explanation and / or Examples 1-3 and Examples 10-11, where the second solvent combination and its ratio is 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 100:60, 62.5:37.5, 187.5:112.5, 10:150, 150:10, etc. Therefore, those skilled in the art can reasonably presume that the technical feature “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190”, its subordinate concepts and their essentially equivalent technical means, and technical means that can replace “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” based on existing technical levels and conventional technical means and common knowledge should all fall within the protection scope of claim 3. For example, if other technical features remain unchanged, replacing “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” with the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10:10, 60:150, etc., still falls within the protection scope of claim 3 of this invention.

[0060] In this invention, embodiments 4-6 and 12-13 at least support the protection scope of claim 5.

[0061] Regarding claim 5: the second solvent combination and its proportions The technical feature “the second solvent combination and its ratio is N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” is summarized from the common feature “the combination and ratio of solvents” in the foregoing explanation and / or the corresponding technical features in Examples 4-6 and Examples 12-13, such as N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 100:60, 62.5:37.5, 187.5:112.5, 10:150, 150:10, etc. Therefore, those skilled in the art can reasonably infer that the technical feature “the second solvent combination and its ratio of N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190”, its subordinate concepts and their essentially equivalent technical means, and technical means that can replace “the second solvent combination and its ratio of N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” within the scope of conventional technical means and common knowledge based on the existing technical level, should all fall within the protection scope of claim 5. For example, if other technical features remain unchanged, replacing “the second solvent combination and its ratio of N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” with the second solvent combination and its ratio of N-methylpyrrolidone and γ-butyrolactone with a volume ratio of 10:10, 60:150, etc., still falls within the protection scope of claim 5 of this invention.

[0062] Embodiments 7-9 and 14-15 of this invention at least support the protection scope of claim 7.

[0063] Regarding claim 7: the second solvent combination and its proportions The technical feature “the second solvent combination and its ratio is 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 10-190:10-190” is summarized from the common feature “the combination and ratio of solvents” in the foregoing explanation and / or the corresponding technical features in Examples 7-9 and Examples 14-15, such as the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 100:60, 62.5:37.5, 187.5:112.5, 10:150, 150:10, etc. Therefore, those skilled in the art can reasonably infer that the technical feature “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 10-190:10-190”, its subordinate concepts and their essentially equivalent technical means, and technical means that can replace “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 10-190:10-190” based on existing technical levels and conventional technical means and common knowledge should all fall within the protection scope of claim 7. For example, if other technical features remain unchanged, replacing “the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 10-190:10-190” with the second solvent combination and its ratio of 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 10:10, 60:150, etc., still falls within the protection scope of claim 7 of this invention.

[0064] Embodiments 1-3 and 10-11 of this invention at least support the protection scope of claim 13.

[0065] Regarding claim 13, which relates to: solvent combination and its proportions The technical feature “solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5” is summarized from the common feature “solvent combination and its ratio” in the foregoing explanation and / or Examples 1-3 and Examples 10-11, which are N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in volume ratios of 8.4:1:0.6, 9:0.625:0.375, 7:1.875:1.125, 8.4:0.1:1.5, 8.4:1.5:0.1, etc. Therefore, based on reasonable presumption, those skilled in the art can determine that the technical feature "the solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5", its subordinate concepts, and its essentially equivalent technical means can be replaced by "the solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9" within the scope of conventional technical means and common knowledge based on the existing level of technology. All technical means of “0.1-1.5” should fall within the protection scope of claim 13. For example, if other technical features remain unchanged, replacing “solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 7-9:0.1-1.9:0.1-1.5” with solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone and its volume ratio of 9:1.9:0.1, etc., still falls within the protection scope of claim 13 of this invention.

[0066] Embodiments 4-6 and 12-13 of this invention at least support the protection scope of claim 15.

[0067] Regarding the solvent combination and its proportions as described in claim 15: The technical feature “solvent combination and its ratio of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5” is summarized from the common feature “solvent combination and its ratio” in the foregoing explanation and / or the corresponding technical features in Examples 4-6 and Examples 12-13, such as N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in volume ratios of 8.4:1:0.6, 9:0.625:0.375, 7:1.875:1.125, 8.4:0.1:1.5, 8.4:1.5:0.1. Therefore, based on reasonable presumption, those skilled in the art can determine that the technical feature "the solvent combination and its ratio of N,N-dimethylformamide, N-methylpyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5", its subordinate concepts, and its essentially equivalent technical means can be replaced by "the solvent combination and its ratio of N,N-dimethylformamide, N-methylpyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5" within the scope of conventional technical means and common knowledge based on the existing level of technology. All technical means described in ".1-1.5" should fall within the protection scope of claim 15. For example, if other technical features remain unchanged, replacing "solvent combination and its ratio of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone and its volume ratio of 7-9:0.1-1.9:0.1-1.5" with "solvent combination and its ratio of N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone and its volume ratio of 7:1.9:0.1" still falls within the protection scope of claim 15 of this invention.

[0068] Embodiments 7-9 and 14-15 of this invention at least support the protection scope of claim 7.

[0069] Regarding claim 17: solvent combination and its proportions The technical feature “solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5” is summarized from the common feature “solvent combination and its ratio” in the foregoing explanation and / or the corresponding technical features in Examples 7-9 and Examples 14-15, such as N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone in volume ratios of 8.4:1:0.6, 9:0.625:0.375, 7:1.875:1.125, 8.4:0.1:1.5, 8.4:1.5:0.1. Therefore, those skilled in the art can reasonably presume that the technical feature solvent combination and its ratio are N,N-dimethylformamide, 1-ethyl-2-pyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0.1-1.5”, its subordinate concepts, and its substantially equivalent technical means. Based on the existing level of technology and within conventional technical means and common knowledge, alternative solvent combinations and their ratios are also N,N-dimethylformamide, 1-ethyl-2-pyrrolidone, and γ-butyrolactone in a volume ratio of 7-9:0.1-1.9:0”. All technical means described in ".1-1.5" should fall within the protection scope of claim 17. For example, if other technical features remain unchanged, replacing the solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 7-9:0.1-1.9:0.1-1.5" with the solvent combination and its ratio of N,N-dimethylformamide, 1-ethyl-2-pyrrolidone and γ-butyrolactone with a volume ratio of 7:1.9:0.1, etc., still falls within the protection scope of claim 17 of this invention.

[0070] The beneficial effects of this invention are as follows: The present invention has at least the following beneficial effects: 1. DMF, NMP, and NEP have high boiling points, which results in a moderate solvent evaporation rate, which is conducive to uniform film formation and avoids coffee ring effect or pinhole defects caused by rapid drying. 2. Ternary solvent systems offer a controllable crystallization rate, providing sufficient time for the perovskite precursor to align in an orderly manner, thus reducing grain boundary defects. The Lewis basicity of these solvents, containing C=O or NC=O groups, allows them to react with Pb. 2+ It forms a stable solvated intermediate, slows down the crystallization rate, and improves the uniformity of the film.

[0071] 3. In outdoor environments, even in the presence of trace amounts of moisture, the solvent still preferentially reacts with Pb. 2+ Coordination reduces hydrolysis side reactions.

[0072] 4. By mixing multiple solvents, the reliability and repeatability of outdoor processing can be further improved, promoting the large-scale production of perovskite indoor photovoltaics. Attached Figure Description

[0073] Figure 1 To prepare a large-area flexible indoor photovoltaic perovskite solar cell module structure using Application Example 1. Detailed Implementation The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0074] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means.

[0075] Table 1

[0076] Examples 1-3: Preparation of Perovskite Precursor Solutions Table 2 Composition and content of perovskite precursor solution

[0077] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0078] Examples 4-6: Preparation of Perovskite Precursor Solutions Table 3 Composition and content of perovskite precursor solution

[0079] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0080] Examples 7-9: Preparation of Perovskite Precursor Solutions Table 4 Composition and content of perovskite precursor solution

[0081] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0082] Examples 10-11: Preparation of Perovskite Precursor Solutions Table 5 Composition and content of perovskite precursor solution

[0083] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0084] Examples 12-13: Preparation of Perovskite Precursor Solutions Table 6 Composition and content of perovskite precursor solution

[0085] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0086] Examples 14-15: Preparation of Perovskite Precursor Solutions Table 7 Composition and content of perovskite precursor solution

[0087] A weak-light perovskite precursor solution composed of CsI, FAI, PbI2, and PbBr2 was dissolved in a mixed solvent of DMF, NEP, and NMP. The prepared precursor solution was filtered and then used for later use.

[0088] Comparative Example 1 The perovskite precursor solution composition differs from that of Example 1, specifically: Table 8 Composition and content of perovskite precursor solution

[0089] The remaining steps are the same as in Example 1.

[0090] Comparative Example 2 The perovskite precursor solution differs from Example 1 in its composition and content, specifically: Table 9 Composition and content of perovskite precursor solution

[0091] The remaining steps are the same as in Example 1.

[0092] Comparative Examples 3-4 The difference from Example 1 is that the solvent ratio and content in the perovskite precursor solution are different, specifically: Table 10 Composition and content of perovskite precursor solution

[0093] The remaining steps are the same as in Example 1.

[0094] Comparative Examples 5-6 The difference from Example 4 is that the solvent ratio and content in the perovskite precursor solution are different, specifically: Table 11 Composition and content of perovskite precursor solution

[0095] The remaining steps are the same as in Example 4.

[0096] Comparative Examples 7-8 The difference from Example 7 is the solvent ratio and content in the perovskite precursor solvent composition, specifically: Table 12 Composition and content of perovskite precursor solution

[0097] The remaining steps are the same as in Example 7.

[0098] Application Example 1: Fabrication of Flexible Perovskite Solar Cells (1) Substrate preparation: P1 etching was performed on a flexible ITO substrate using a red nanosecond laser to separate multiple sub-cells from the bottom, resulting in PET; (2) Preparation of conductive substrate: After P1 is scratched in PET / ITO, the conductive substrate is obtained by spray cleaning → brush cleaning → ultrasonic cleaning → two-fluid cleaning → spray cleaning → air knife drying. (3) Preparation of NiOx hole transport layer by magnetron sputtering: The cleaned flexible substrate was placed in a magnetron sputtering device with a sputtering power of 2000W, an argon flow rate of 400sccm, an oxygen flow rate of 2sccm, and sputtered at room temperature for 3 cycles to obtain a 20nm thick NiOx hole transport layer. (4) Preparation of self-assembled monolayer: The self-assembled monolayer is a Me-4PACz solution with a concentration of 0.5 mg / mL and ethanol as the solvent. The Me-4PACz solution is deposited on the NiOx transport layer by slit coating at a coating speed of 5 mm / s, a liquid injection speed of 8 μL / s, and a gap of 100 μm. The self-assembled monolayer film is obtained by annealing at 100 °C for 10 min. (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 1. The specific parameters were set as follows: coating speed 12 mm / s, gap height 150 μm, injection speed 28 μL / s, VCD: 10s to 10 Pa, 10 Pa holding pressure for 40s; immediately transferred to infrared light wave furnace for low-temperature pre-annealing. The first stage of pre-annealing temperature was 100℃ and the pre-annealing time was 10 min. In the second stage, the perovskite film was placed face down on the heating plate, ensuring that the distance between the film and the heating plate was 5 cm; then high-temperature annealing was performed at 150℃ for 20 min to obtain the perovskite active layer film. (6) Preparation of electron transport layer: deposition of C 60 A 15nm C layer was deposited on the surface of the perovskite active layer using a thermal evaporation method. 60 (fullbody); (7) Preparation of hole transport layer: 25 nm SnOx was deposited on the C60 surface by ALD in-situ atomic deposition; (8) Preparation of metal electrodes (8.1) P2 etching: P2 etching is performed using a green picosecond laser to remove the electron transport layer, perovskite active layer, self-assembled monolayer and hole transport layer in the P2 region, which serves as the interconnection region between the metal top electrode and the flexible ITO bottom electrode. (8.2) Copper electrode deposition: A 150 nm copper electrode was deposited on the SnOx surface after P2 was drawn by thermal evaporation. (8.3) P3 etching: P3 etching is performed using a green picosecond laser to cut off the P3 metal region and separate multiple sub-cells from the top to obtain a flexible perovskite solar cell module.

[0099] Application Example 2: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with perovskite precursor solution prepared in Example 2. The remaining steps were the same as in Application Example 1.

[0100] Application Example 3: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 3. The remaining steps were the same as in Application Example 1.

[0101] Application Example 4: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 4. The remaining steps were the same as in Application Example 1.

[0102] Application Example 5: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 5. The remaining steps were the same as in Application Example 1.

[0103] Application Example 6: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 6. The remaining steps were the same as in Application Example 1.

[0104] Application Example 7: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating the perovskite precursor solution prepared in Example 7. The remaining steps were the same as in Application Example 1.

[0105] Application Example 8: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating the perovskite precursor solution prepared in Example 8. The remaining steps were the same as in Application Example 1.

[0106] Application Example 9: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating the perovskite precursor solution prepared in Example 9. The remaining steps were the same as in Application Example 1.

[0107] Application Example 10: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 10. The remaining steps were the same as in Application Example 1.

[0108] Application Example 11: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Example 11. The remaining steps are the same as in Application Example 1.

[0109] Application Example 12: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 12. The remaining steps were the same as in Application Example 1.

[0110] Application Example 13: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 13. The remaining steps were the same as in Application Example 1.

[0111] Application Example 14: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 14. The remaining steps were the same as in Application Example 1.

[0112] Application Example 15: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Example 15. The remaining steps are the same as in Application Example 1.

[0113] Comparative Example 1: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with the perovskite precursor solution prepared in Comparative Example 1. The remaining steps are the same as in Application Example 1.

[0114] Comparative Example 2: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 2. The remaining steps are the same as in Application Example 1.

[0115] Comparative Example 3: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 3. The remaining steps are the same as in Application Example 1.

[0116] Comparative Example 4: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 4. The remaining steps are the same as in Application Example 1.

[0117] Comparative Example 5: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 5. The remaining steps are the same as in Application Example 1.

[0118] Comparative Example 6: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 6. The remaining steps are the same as in Application Example 1.

[0119] Comparative Example 7: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 7. The remaining steps are the same as in Application Example 1.

[0120] Comparative Example 8: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer is prepared by slit coating with perovskite precursor solution prepared in Comparative Example 8. The remaining steps are the same as in Application Example 1.

[0121] Comparative Example 9: Fabrication of Flexible Perovskite Solar Cells The perovskite active layer preparation differs from that in Application Example 1, specifically as follows: (5) Preparation of perovskite active layer: Wide-bandgap perovskite active layer was prepared by slit coating with the perovskite precursor solution prepared in Example 1. The specific parameters were set as follows: coating speed 12 mm / s, gap height 150 μm, injection speed 28 μL / s, VCD: 10 s to 10 Pa, 10 Pa holding pressure for 40 s; immediately transferred to tunnel furnace for low-temperature pre-annealing. The first stage of pre-annealing temperature was 100 °C and the pre-annealing time was 10 min. In the second stage, the perovskite film was placed face down on the heating plate, ensuring that the distance between the film and the heating plate was 5 cm; then high-temperature annealing was performed at 150 °C for 20 min to obtain the perovskite active layer film. The remaining steps were the same as in Application Example 1.

[0122] Test Example 1: Photovoltaic Performance Testing of Flexible Perovskite Solar Cells 1. Testing method: The size of the prepared component is 10 × 10 cm. 2 The aperture area is 88.47 cm². 2 , structure as Figure 1 As shown in Table 13, the device's performance was tested by simulating low indoor light illumination under LED conditions of 3000K and 200 lux. The measured performance parameters included photoelectric conversion efficiency (Eff), open-circuit voltage (Voc), short-circuit current (Isc), and fill factor (FF). The obtained photovoltaic performance parameters are shown in Table 13.

[0123] 2. Test Results According to the test results in Table 13 below, compared with Comparative Example 9, the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the flexible perovskite solar cells prepared by Examples 1-15 were all improved. The infrared light wave furnace pre-annealing process can effectively improve the cell performance. This proves that there is a synergistic effect between the specific solvent system and the annealing process, which can significantly improve the photovoltaic performance of flexible perovskite solar cells.

[0124] Compared to Comparative Examples 1-9, the performance of flexible perovskite solar cells prepared in Application Examples 1-15 was significantly improved. Compared to Comparative Examples 1-2, the open-circuit voltage, fill factor, and photoelectric conversion efficiency of the flexible perovskite solar cells prepared in Application Examples 1-15 were all effectively improved. This indicates that the selection of a specific solvent system has a significant impact on the performance of flexible perovskite solar cells. The specific solvent system composed of DMF, NEP, and NMP has a moderate evaporation rate, which is beneficial for uniform film formation and avoids the coffee ring effect or pinhole defects caused by rapid drying. This allows the perovskite active layer to have a controllable crystallization rate, thus providing sufficient time for the perovskite precursor to align in an orderly manner and reducing grain boundary defects.

[0125] Compared to Comparative Examples 3-8, the photoelectric conversion efficiency of flexible perovskite solar cells prepared in Application Examples 1-15 is higher than 34%. An unexpected finding was that the volume ratio of the first and second solvents in the perovskite precursor solvent system may have a significant impact on the photoelectric conversion efficiency of the prepared flexible perovskite solar cells.

[0126] In summary, this invention, through the synergistic effect of specific solvent combinations and ratios and annealing processes, combined with specific additives, prepares a perovskite activation layer for use in the subsequent fabrication of flexible perovskite solar cells. This effectively improves the photovoltaic performance of flexible perovskite solar cells in indoor low-light environments and has significant application value.

[0127] Table 13 Photovoltaic Performance Test Results of Flexible Perovskite Solar Cells

[0128] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A perovskite precursor solution for preparing flexible photovoltaic modules, characterized in that, The invention comprises perovskite material, solvent, and additives. The solvent is a mixture of a first solvent and a second solvent. The first solvent is N,N-dimethylformamide. The second solvent is selected from one or more of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, γ-butyrolactone, tetrahydrofuran, acetonitrile, and 2-methoxyethanol. The volume ratio of the first solvent to the second solvent is 7-9:1-3. The additive is a mixture of potassium thiocyanate and rubidium thiocyanate; The concentration of the perovskite material in the perovskite precursor solution is 1M.

2. The perovskite precursor solution according to claim 1, characterized in that, The perovskite materials mentioned include cesium iodide, formamidinium iodide, lead bromide, and lead iodide; The second solvent is at least two of N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, and γ-butyrolactone.

3. The perovskite precursor solution according to claim 2, characterized in that, The second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio of 10-190:10-190.

4. The perovskite precursor solution according to claim 3, characterized in that, The second solvent is a mixture of N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio of 10-190:10-150.

5. The perovskite precursor solution according to claim 2, characterized in that, The second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 10-190:10-190.

6. The perovskite precursor solution according to claim 5, characterized in that, The second solvent is a mixture of N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 10-190:10-150.

7. The perovskite precursor solution according to claim 2, characterized in that, The second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 10-190:10-190.

8. The perovskite precursor solution according to claim 7, characterized in that, The second solvent is a mixture of 1-ethyl-2-pyrrolidone and γ-butyrolactone in a volume ratio of 10-190:10-150.

9. The perovskite precursor solution according to claim 1, characterized in that, The additives, by weight percentage, are 2% potassium thiocyanate and 2% rubidium thiocyanate.

10. The use of the perovskite precursor solution according to any one of claims 1-9 in the preparation of flexible indoor photovoltaic modules.

11. A flexible indoor photovoltaic module, characterized in that, The flexible indoor photovoltaic module comprises a perovskite active layer, a substrate, a conductive substrate, a hole transport layer, a self-assembled monolayer, an electron transport layer, and a metal top electrode, prepared from the perovskite precursor solution described in any one of claims 1-9.

12. The method for preparing the flexible indoor photovoltaic module according to claim 11, characterized in that, The preparation of the perovskite active layer includes the following steps: (1) Preparation of perovskite precursor solution: Dissolve perovskite material and additives in solvent, filter, and set aside; (2) Preparation of perovskite active layer: The perovskite precursor solution prepared in step (1) is coated on the self-assembled monolayer film by slit coating method, and the perovskite active layer film is obtained after annealing.

13. The preparation method according to claim 12, characterized in that, The solvent used in step (1) has a volume ratio of 7-9: 0.1-1.9: 0.1-1.5% of a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone.

14. The preparation method according to claim 13, characterized in that, The solvent in step (1) is a mixture of N,N-dimethylformamide, N-methylpyrrolidone and 1-ethyl-2-pyrrolidone in a volume ratio of 8.4:1:0.

6.

15. The preparation method according to claim 12, characterized in that, The solvent used in step (1) has a volume ratio of 7-9: 0.1-1.9: 0.1-1.5 N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone.

16. The preparation method according to claim 15, characterized in that, The solvent in step (1) is N,N-dimethylformamide, N-methylpyrrolidone and γ-butyrolactone in a volume ratio of 8.4:1:0.

6.

17. The preparation method according to claim 12, characterized in that, The solvent used in step (1) has a volume ratio of 7-9: 0.1-1.9: 0.1-1.5% of a mixture of N,N-dimethylformamide, γ-butyrolactone and 1-ethyl-2-pyrrolidone.

18. The preparation method according to claim 17, characterized in that, The solvent in step (1) is a mixture of N,N-dimethylformamide, γ-butyrolactone and 1-ethyl-2-pyrrolidone in a volume ratio of 8.4:1:0.

6.

19. The preparation method according to claim 12, characterized in that, The annealing described in step (2) is a two-step annealing method. The first step is low-temperature pre-annealing, and the second step is high-temperature annealing.

20. The preparation method according to claim 19, characterized in that, The low-temperature pre-annealing is carried out in an infrared light wave furnace.

21. The preparation method according to claim 19, characterized in that, The high-temperature annealing is carried out on a hot bench.

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