A ferroelectric material modified perovskite solar cell and a preparation method thereof

Abstract

The application discloses a ferroelectric material modified perovskite solar cell and a preparation method thereof. The ferroelectric material modified perovskite solar cell is composed of a transparent conductive substrate, an electron transport layer, a perovskite active layer and a carbon electrode which are sequentially stacked. The active layer is prepared from a perovskite material doped with a ferroelectric material (C6H5CH2NH3)2CsPb2Br7. The doping concentration of the ferroelectric material is 0.01-0.05 mol%. The spontaneous polarization characteristics of (C6H5CH2NH3)2CsPb2Br are used to enhance the built-in electric field in the device, inhibit non-radiative recombination, significantly improve the photoelectric conversion efficiency and stability of the cell, and the process is simple and the cost is controllable. The technical bottleneck of poor stability, weak built-in electric field and poor material adaptability of the existing carbon-based perovskite solar cell is solved, and the application can be widely used in the fields of photovoltaic power generation, portable electronic device power supply and building photovoltaic integration.

Description

Technical Field

[0001] This invention relates to the field of novel photovoltaic materials and device fabrication technology, specifically to a ferroelectric material modified perovskite solar cell and its fabrication method. Background Technology

[0002] Since their initial report by Miyasaka's group in 2009, organic-inorganic halide perovskite solar cells (PSCs) have rapidly emerged as a research hotspot in next-generation photovoltaic technology, attracting widespread attention from the global scientific and industrial communities due to their excellent photoelectric performance, low fabrication cost, simple solution processing technology, and good flexibility. After more than a decade of rapid development, the certified photoelectric conversion efficiency (PCE) of perovskite solar cells has steadily climbed from the initial 3.8% to 27.3%, gradually approaching that of commercially viable silicon-based solar cells, demonstrating extremely broad industrialization prospects.

[0003] Among the many types of perovskite solar cells, carbon-based perovskite solar cells (C-PSCs) have become a key technological path for promoting the large-scale application of perovskite solar cells due to their unique structural and cost advantages. Traditional perovskite solar cells typically use precious metals such as gold and silver as electrode materials, and require the addition of expensive hole transport layers (such as Spiro-OMeTAD). This not only significantly increases the manufacturing cost of the device and limits its large-scale production, but also results in poor long-term stability of the device due to the susceptibility of precious metal electrodes to oxidation and the susceptibility of the hole transport layer to water absorption and degradation, making it difficult to meet the requirements of practical applications. Carbon-based perovskite solar cells use inexpensive, stable, and widely available carbon materials (such as carbon paste, graphene, and carbon nanotubes) to replace traditional precious metal electrodes. At the same time, there is no need to add an additional hole transport layer, forming a simplified structure of "carbon electrode - perovskite active layer - electron transport layer - conductive substrate". This also significantly simplifies the fabrication process. More importantly, carbon materials have excellent anti-oxidation and anti-moisture properties, which can effectively improve the long-term stability of the device and solve the core pain points of traditional perovskite solar cells: "high cost and poor stability".

[0004] Despite the numerous advantages mentioned above, carbon-based perovskite solar cells still face several pressing technical bottlenecks in practical applications. These bottlenecks severely limit further improvements in photoelectric conversion efficiency and the advancement of industrialization. Specifically, the main problems are as follows: First, device stability still needs further improvement. Although the introduction of carbon electrodes improves device stability, the perovskite active layer is in direct contact with the carbon electrodes and water and oxygen in the external environment. The ionic properties of the perovskite material itself make it prone to decomposition and degradation, forming impurity phases such as PbI2, which leads to rapid degradation of device performance. In existing technologies, unencapsulated carbon-based perovskite solar cells stored at 18–28°C and 45%–65% RH for 1000 days... After h, the photoelectric conversion efficiency retention rate is usually less than 70%, far below the 85% or more required for practical applications; secondly, the improvement of photoelectric conversion efficiency is limited. During the preparation of the perovskite active layer, a large number of defects (such as vacancy defects, interstitial defects, interface defects, etc.) are easily generated. These defects become centers for carrier recombination, leading to severe non-radiative recombination losses. Simultaneously, the built-in electric field of the device is weak, resulting in insufficient carrier separation and transport power, and electrons and holes easily recombine. This causes the photoelectric conversion efficiency of existing unmodified carbon-based perovskite solar cells to generally be below 18%, a significant gap from the theoretical efficiency (approximately 33%); thirdly, the compatibility of modification materials is poor. Most additives used for modifying perovskite solar cells in existing technologies (such as organic amine salts, metal oxides, quantum dots, etc.) can only be used in single perovskite systems (such as lead formamidinium). The modification effects of ferroelectric materials are limited in iodine-based and cesium-lead-bromine-based systems, and most additives lack a clear mechanism of action, failing to fundamentally solve the problems of carrier recombination and excessive defects in the active layer. Fourth, ferroelectric modification technology is imperfect. Ferroelectric materials, due to their spontaneous polarization characteristics, can build additional built-in electric fields inside devices, effectively promoting carrier separation and transport, suppressing non-radiative recombination, and passivating defects in the perovskite active layer. They are ideal modification materials for optimizing the performance of perovskite solar cells. However, in current research, there is a lack of clear standards for the selection of ferroelectric materials, and most traditional ferroelectric materials are used. These materials have poor compatibility with the perovskite active layer, easily destroy the perovskite phase structure, and have limited modification effects, resulting in insufficient innovation and practicality of ferroelectric modification technology, and failing to fully utilize the modification advantages of ferroelectric materials.

[0005] To address the aforementioned technical bottlenecks, various improvement methods have been attempted in existing technologies, but all have limitations and cannot fundamentally solve the problem. For example, while additive / solvent engineering can regulate crystallization kinetics and improve film quality, it cannot solve the energy level mismatch problem at the perovskite / carbon electrode interface, and nonradiative recombination remains severe. Surface / interface defect passivation can reduce some defects, but the process is complex and costly, and it cannot enhance the built-in electric field of the device, resulting in insufficient carrier separation momentum. Introducing a hole transport layer or modifying the carbon electrode can optimize the energy level arrangement and reduce electrode resistance, but it often increases process complexity and cost, and it is difficult to simultaneously suppress carrier recombination, enhance the built-in electric field, and improve long-term stability. Summary of the Invention

[0006] To overcome the aforementioned shortcomings and deficiencies of the prior art, the present invention aims to provide a ferroelectric modified perovskite solar cell. This cell uses BzCPB (full name (C6H5CH2NH3)2CsPb2Br7), which possesses distinct ferroelectric properties, as a modifier. This addresses the problems of poor stability, low photoelectric conversion efficiency, insufficient compatibility of modified materials, and imperfect ferroelectric modification technology in existing carbon-based perovskite solar cells. The invention achieves simultaneous improvement in device efficiency and stability, while reducing manufacturing costs and simplifying the manufacturing process.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] This invention provides a ferroelectric material modified perovskite solar cell, which is composed of a transparent conductive substrate, an electron transport layer, a perovskite active layer and a carbon electrode arranged sequentially.

[0009] The active layer is prepared from a perovskite material doped with ferroelectric material BzCPB; the doping concentration of BzCPB in the active layer is 0.01-0.05 mol%; the perovskite material is a cesium formamidinium lead halide-based perovskite material, wherein the halogen is selected from at least one of bromine and iodine, and its general chemical formula is FA. x Cs (1-x) PbI y Br (3-y) , where 0≤x≤1, 0≤y≤3.

[0010] In some embodiments of the present invention, the transparent conductive substrate is FTO or ITO, preferably FTO.

[0011] In some embodiments of the present invention, the perovskite material is preferably a cesium formamidinium lead halide-based perovskite material, and more preferably FA. 0.83 Cs 0.17 PbI3 and FAPbBr3.

[0012] In some embodiments of the present invention, the electron transport layer is SnO2, TiO2, or ZnO, preferably SnO2.

[0013] In some embodiments of the present invention, the thickness of the active layer is 200-1000 nm; the thickness of the carbon electrode is 5-30 μm.

[0014] The present invention also provides a method for preparing the ferroelectric material modified perovskite solar cell, comprising the following steps:

[0015] Preparation of ferroelectric material BzCPB: Lead source, benzylamine source, cesium source and bromine source were weighed according to stoichiometric ratio and mixed. The mixture was heated and stirred until dissolved, cooled and crystallized to obtain ferroelectric material BzCPB.

[0016] Clean the transparent conductive substrate;

[0017] Prepare a SnO2 electron transport layer on a transparent conductive substrate;

[0018] Ferroelectric material BzCPB was added to the perovskite precursor solution, stirred evenly, and then spin-coated onto the surface of the SnO2 electron transport layer. After annealing, a ferroelectric material-doped perovskite active layer was formed.

[0019] Carbon paste was coated onto the active layer and then annealed and cured to obtain a ferroelectric material modified perovskite solar cell.

[0020] In some embodiments of the present invention, the benzylamine source is a benzylamine solution with a purity of 99%, the cesium source is cesium carbonate, and the bromine source is hydrobromic acid; when preparing the ferroelectric material BzCPB, the heating temperature is 75-85℃, the stirring time is 25-35 min, the cooling rate is 4-5℃ / h, and the material is cooled to room temperature for crystallization.

[0021] In some embodiments of the present invention, the cleaning of the transparent conductive substrate specifically involves: using glass cleaner, deionized water, and acetone as cleaning media in sequence, ultrasonically cleaning and drying the transparent conductive substrate to complete the cleaning process.

[0022] In some embodiments of the present invention, when the cesium formamidinium lead halide-based perovskite material is FA 0.83 Cs 0.17 For PbI3, the spin coating process for the active layer is as follows: spin coating at a speed of 4000-6000 rpm / s for 40-60 s; the annealing process parameters for the active layer are as follows: annealing at 100-150℃ for 10-15 min.

[0023] When the cesium carbamate lead halide-based perovskite material is FAPbBr3, the spin coating process of the active layer is as follows: spin coating at a speed of 4000-6000 rpm / s for 40-60 s, and adding the anti-solvent ethyl acetate dropwise during the middle and later stages of spin coating; the annealing process parameters of the active layer are as follows: annealing at 100-150℃ for 30-40 min.

[0024] In some embodiments of the present invention, the preparation of the SnO2 electron transport layer specifically involves: treating the cleaned transparent conductive substrate with ultraviolet ozone, reacting the transparent conductive substrate with a SnCl2 precursor solution diluted six times at a constant temperature, and then cleaning and annealing to obtain the SnO2 electron transport layer.

[0025] The present invention also provides applications of the ferroelectric material modified perovskite solar cells described above, for use in the fields of photovoltaic power generation, power supply for portable electronic devices, and building-integrated photovoltaics.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The present invention uses BzCPB, which has obvious ferroelectric properties, as a modifier. It can build an additional built-in electric field inside the device, effectively promote the separation and transport of charge carriers, suppress non-radiative recombination loss, and at the same time form hydrogen bonds with the perovskite active layer, passivate the defects of the perovskite active layer, reduce the charge carrier recombination centers, thereby simultaneously improving the photoelectric conversion efficiency and long-term stability of the battery, solving the core pain points of low efficiency and poor stability of existing carbon-based perovskite solar cells.

[0028] (2) The BzCPB and cesium formamidinium lead halide-based perovskite system used in this invention have good compatibility and adaptability, and the modification effect is stable. There is no need to adjust the modifying material for different perovskite systems, which broadens the scope of application of this invention and makes it more practical. At the same time, the entire preparation process is simple and convenient to operate, without the need for complex preparation equipment, and the preparation cost is controllable, making it suitable for large-scale industrial production.

[0029] (3) The battery prepared by the present invention adopts an all-solid-state layered structure, which does not require the addition of a hole transport layer, simplifies the device structure, further reduces the preparation cost, and at the same time, there is no additional interface layer between the carbon electrode and the perovskite active layer, which reduces interface defects and carrier recombination loss, improves the stability and photoelectric performance of the battery, and broadens its application scenarios.

[0030] (4) The battery of the present invention has excellent photoelectric performance, good long-term stability and low manufacturing cost, and can be widely used in the fields of photovoltaic power generation, power supply for portable electronic devices and building-integrated photovoltaics. In practical applications, the battery can be used as a standalone power supply unit to provide stable power to small electronic devices, or it can be combined to form a photovoltaic module for large-scale photovoltaic power generation, thus broadening the application scenarios of carbon-based perovskite solar cells and having broad prospects for industrial application. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a ferroelectric material modified perovskite solar cell according to an embodiment of the present invention; wherein 1 is a transparent conductive substrate, 2 is an electron transport layer, 3 is a perovskite active layer and 4 is a carbon electrode.

[0032] Figure 2 This is a schematic diagram illustrating the working principle of a ferroelectric material-modified perovskite solar cell according to an embodiment of the present invention.

[0033] Figure 3 The images show the infrared spectra of the perovskite (PVK), BzCPB ferroelectric material, and BzCPB-doped perovskite composite system prepared in Example 1 of this invention; where B, C, and D are magnified views of A.

[0034] Figure 4 The diagram shows the ferroelectric properties of the BzCPB ferroelectric material of this invention; where A is the ferroelectric hysteresis loop (PE) at 346 K and B is the corresponding current-electric field (IE) curve.

[0035] Figure 5 This is a comparison chart of the JV curves of the devices prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention.

[0036] Figure 6 This is a comparison chart showing the efficiency retention of the devices prepared in Example 1 and Comparative Example 3 after being stored at room temperature and humidity for 2000 hours.

[0037] Figure 7 This is a comparison chart of the JV curves of the FAPbBr3 system battery prepared in Example 2 of the present invention and the device prepared in Comparative Example 4. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that "FA" in this invention refers to asamidine ions (CH(NH2)2). + “Cs” refers to cesium ion, “Pb” to lead ion, “I” to iodide ion, “Br” to bromide ion, and “Cl” to chloride ion; “BzCPB” refers to benzylamine cesium lead bromide compound (C6H5CH2NH3)2CsPb2Br7; “IBA” refers to isobutylamine, “EA” to ethylamine, and “Cl-PMA” to 4-chlorobenzylamine; “PCE” refers to photoelectric conversion efficiency; “J” refers to the photoelectric conversion efficiency. SC "V" refers to short-circuit current density; OC "FF" refers to open-circuit voltage; "RH" refers to fill factor; all raw materials are commercially available conventional products that can be purchased directly. Unless otherwise specified, the preparation processes are conventional laboratory operation processes that can be achieved without additional optimization.

[0040] This invention discloses a ferroelectric material-modified perovskite solar cell and its preparation method. The core of this invention lies in selecting BzCPB, which exhibits excellent compatibility with the perovskite system and clearly defined ferroelectric properties, as a modifier. Through a rationally designed preparation process, uniform doping of BzCPB in the perovskite active layer is achieved, constructing a simplified all-solid-state layered structure and simultaneously improving the photoelectric conversion efficiency and long-term stability of the cell. This invention designs and synthesizes two structurally similar ferroelectric materials, and constructs a complete comparative verification system using a blank control device and the controlled variable method. This accurately verifies the unique advantages of BzCPB in perovskite cell modification, effectively eliminating interference from other factors besides the ferroelectric effect, such as organic cation structure, functional groups, and synthesis process. This fully demonstrates the technical innovation and practical application value of this invention, significantly enhancing the persuasiveness of the technical solution. The invention will be further described in detail below through specific embodiments.

[0041] like Figure 1 As shown, the ferroelectric material modified perovskite solar cell of the present invention is composed of a transparent conductive substrate 1, an electron transport layer 2, a perovskite active layer 3 and a carbon electrode 4 arranged sequentially.

[0042] The active layer is made of perovskite material doped with ferroelectric material BzCPB; the doping concentration of ferroelectric material BzCPB in the active layer is 0.01-0.05 mol%; the perovskite material is cesium formamidinium lead halide-based perovskite material.

[0043] The ferroelectric material-modified perovskite solar cell of this invention lacks a hole transport layer. The ferroelectric modification of BzCPB can compensate for the shortcomings in carrier extraction and improve the hole transport efficiency to the carbon electrode by enhancing the built-in electric field. Ferroelectric material (BzCPB) is doped at a low concentration (0.01-0.05 mol%) inside the perovskite active layer to form a single-doped active layer. The built-in electric field generated by the spontaneous polarization of BzCPB inside the perovskite active layer penetrates the entire active layer, accelerating carrier transport from the source.

[0044] The working principle of the ferroelectric material modified perovskite solar cell of the present invention is as follows: Figure 2 As shown, through 3D cesium formamidinium lead halide perovskite (general formula FA) x Cs (1-x) PbI y Br (3-y) The introduction of the ferroelectric material BzCPB enables dimensional control of the transformation from 3D perovskite to 2D / 3D hybrid perovskite structures. BzCPB possesses spontaneous polarization properties, allowing the construction of a stable built-in electric field within the perovskite active layer. Under illumination, this built-in electric field effectively drives photogenerated electrons (electrons). - ) and holes (h + The directional separation and transport of charge carriers can suppress nonradiative recombination, thereby improving the photoelectric conversion efficiency and long-term stability of carbon-based perovskite solar cells.

[0045] Example 1

[0046] This embodiment prepares FA 0.83 Cs 0.17 The specific steps for modifying perovskite solar cells with PbI3 ferroelectric materials are as follows:

[0047] (1) Preparation of ferroelectric material BzCPB

[0048] Accurately weigh 5 mmol lead acetate trihydrate (Pb(CH3COO)2·3H2O), 6.54 mmol benzylamine solution with a purity of 99%, and 2.46 mmol cesium carbonate (Cs2CO3), place them in a reaction flask, add 40 mL of 43% hydrobromic acid (HBr), place the reaction flask in an oil bath at 80°C, turn on the stirrer, and stir continuously for 30 min until all raw materials are completely dissolved and a homogeneous and transparent reaction system is formed. Subsequently, the oil bath heating device was turned off, and the cooling rate was controlled at 5℃ / h to slowly cool down to room temperature. At this time, a large number of white crystals appeared in the reaction system. The crystals were filtered using a vacuum filtration device and washed three times with isopropanol to remove residual impurities and unreacted raw materials on the crystal surface. The washed crystals were then dried in a vacuum drying oven at 60℃ for 4 h to obtain white powdered BzCPB ferroelectric material. The yield was 86.2%, and it was found to be a non-centrosymmetric Cmc21 space group at 300 K. The ferroelectric polarization value at 346 K was 1.3 μC / cm², and the Curie temperature was 158℃. The ferroelectric properties were clearly defined, and it can be used for the subsequent modification and preparation of perovskite solar cells.

[0049] (2) Cleaning treatment of FTO conductive glass:

[0050] FTO conductive glass was cut into 1.5 cm × 2 cm pieces and sequentially placed in cleaning tanks containing glass cleaner, deionized water, and acetone for ultrasonic cleaning. Each ultrasonic cleaning step lasted 20-45 minutes at a power of 80-100 W. The ultrasonic vibration thoroughly removed oil, dust, and residual contaminants from the surface of the FTO conductive glass. After each ultrasonic cleaning step, the FTO conductive glass was removed, and the surface moisture was dried with nitrogen gas. Then, it was placed in a forced-air drying oven at 60-90℃ for 1-10 hours. After drying, it was removed and placed in a desiccator for later use.

[0051] (3) Preparation of SnO2 electron transport layer:

[0052] The dried FTO conductive glass from step (2) is placed in an ultraviolet ozone cleaner for 20-50 minutes of ultraviolet ozone treatment to improve the hydrophilicity and surface energy of the FTO conductive glass surface and enhance its bonding with the subsequent SnO2 electron transport layer.

[0053] Meanwhile, prepare the SnCl2 precursor solution: In 50 mL of deionized water, add 0.625 g of urea, 0.1375 g of stannous chloride dihydrate (SnCl2·2H2O), 625 μL of concentrated hydrochloric acid (37% by mass) and 12.5 μL of mercaptoacetic acid in sequence. Turn on the stirrer and stir for 10-30 min until all raw materials are completely dissolved to form a uniform and transparent SnCl2 precursor solution. Then dilute the SnCl2 precursor solution 6 times with ultrapure water, stir evenly and set aside.

[0054] FTO conductive glass treated with UV ozone was immersed in a diluted SnCl2 precursor solution and placed in a constant temperature water bath at 60-90 °C for 1.5-2.5 h. After the reaction was completed, the FTO conductive glass was removed and ultrasonically cleaned sequentially with deionized water and isopropanol for 5 min to remove residual precursor solution. It was then dried and annealed at 180 °C for 1 h, followed by natural cooling to room temperature. A uniform and dense SnO2 electron transport layer was finally prepared on the surface of the FTO conductive glass. Before spin-coating the perovskite layer, it was again placed in a UV ozone cleaner for 20-50 min of UV ozone treatment.

[0055] (4) FA 0.83 Cs 0.17 Preparation of PbI3 perovskite precursor solution:

[0056] Accurately weigh FAI (formamidinium iodide), CsI (cesium iodide), PbI2 (lead iodide), and PbCl2 (lead chloride) according to stoichiometric ratios, wherein the molar ratio of FAI to CsI is 0.83:0.17, and the molar ratio of lead chloride to lead iodide is 1:10. Place the above perovskite raw materials into a beaker, add a mixed solvent of NMP (N-methylpyrrolidone) and DMF (N,N-dimethylformamide) (NMP (molar ratio of PbI2 to NMP:1)), and stir for 1-48 h until all raw materials are completely dissolved to prepare FA with a concentration of 1.8-2.3 M. 0.83 Cs 0.17 PbI3 perovskite precursor solution.

[0057] Subsequently, the BzCPB prepared in step (1) was added to the perovskite precursor solution at a concentration of 0.01-0.05 mol% (calculated based on the total amount of material in the perovskite active layer), and stirring was continued for 0.5-1 h to ensure that the BzCPB was completely and uniformly dispersed, thus obtaining BzCPB-doped FA. 0.83 Cs 0.17 The PbI3 perovskite precursor solution was placed in a desiccator for later use.

[0058] (5) Preparation of perovskite active layer doped with ferroelectric materials:

[0059] Take out the FTO conductive glass with the SnO2 electron transport layer prepared in step (3), place it on a spin coater, and then apply the BzCPB-doped FA prepared in step (4). 0.83 Cs 0.17 The PbI3 perovskite precursor solution was uniformly drop-coated onto the surface of the SnO2 electron transport layer. The spin coating parameters were set as follows: spin speed of 4000-6000 rpm / s and spin coating time of 40-60 s. The spin coater was then turned on to complete the spin coating operation.

[0060] After spin coating, the FTO conductive glass is quickly placed on a hot plate at 150°C for annealing for 10-15 minutes. The annealing process removes the solvent from the film and promotes the growth and crystallization of perovskite crystals. After annealing, the film is naturally cooled to room temperature, forming a dense and well-crystallized ferroelectric material-doped perovskite active layer on the surface of the SnO2 electron transport layer.

[0061] (6) Carbon electrode preparation and battery assembly:

[0062] On the surface of the perovskite active layer prepared in step (5), an effective working area of ​​0.071 cm² is defined using a mask template. Then, carbon paste with a purity of 99.9% is uniformly coated onto the defined effective working area. The coating thickness is controlled to be 5-30 μm. After coating, it is placed on a hot plate at 120℃ for annealing for 10-15 min to allow the carbon paste to fully solidify and form a stable carbon electrode with good conductivity.

[0063] After annealing and curing, allow it to cool naturally to room temperature. Slowly remove the residue-free tape, taking care not to damage the perovskite active layer and carbon electrode, ultimately obtaining FA. 0.83 Cs 0.17 PbI3 system ferroelectric material modified perovskite solar cells.

[0064] Example 2

[0065] This embodiment describes the preparation of FAPbBr3 system ferroelectric material modified perovskite solar cells, and the specific steps are as follows:

[0066] (1) Preparation of ferroelectric material BzCPB: The process is completely consistent with step (1) in Example 1, and BzCPB ferroelectric material is obtained (yield 86.2%, ferroelectric properties are clear). BzCPB is used for subsequent modification and preparation of perovskite solar cells.

[0067] (2) Cleaning treatment of FTO conductive glass: consistent with step (2) in Example 1.

[0068] (3) Preparation of SnO2 electron transport layer: consistent with step (3) of Example 1.

[0069] (4) Preparation of FAPbBr3 perovskite precursor solution:

[0070] Accurately weigh FABr (formamidinium bromide), PbBr2 (lead bromide), and MACl (methylammonium chloride) according to stoichiometric ratios, wherein the molar ratio of FABr to PbBr2 is 1:1, and the amount of MACl added is 5% of the molar amount of FABr. Place the above perovskite raw materials into a beaker, add a mixed solvent of γ-valerolactone, DMF, and DMSO (dimethyl sulfoxide) (the volume ratio of γ-valerolactone:DMF:DMSO is 5:3:2), stir evenly, and then place in a water bath at 40-60℃ and stir for 15-30 min until all raw materials are completely dissolved to prepare a 2.0-2.3 M FAPbBr3 perovskite precursor solution.

[0071] Subsequently, the BzCPB prepared in step (1) was added to the above perovskite precursor solution at a concentration of 0.01-0.05 mol% (calculated based on the total amount of material in the perovskite active layer), and the mixture was stirred for 0.5-1 h to ensure that the BzCPB was completely and uniformly dispersed, thus obtaining the BzCPB-doped FAPbBr3 perovskite precursor solution, which was then placed in a desiccator for later use.

[0072] (5) Preparation of perovskite active layer doped with ferroelectric materials:

[0073] Take out the FTO conductive glass with SnO2 electron transport layer prepared in step (3), place it on a spin coater, and uniformly drop the BzCPB-doped FAPbBr3 perovskite precursor solution prepared in step (4) onto the surface of the SnO2 electron transport layer. Set the spin coating parameters: rotation speed of 4000-6000 rpm / s, spin coating time of 40-60 s. Turn on the spin coater, and quickly drop the antisolvent ethyl acetate in the middle and late stages of spin coating to complete the spin coating operation.

[0074] After spin coating, the FTO conductive glass is quickly placed on a hot plate at 150°C for annealing for 30-40 minutes. The annealing process removes the solvent and anti-solvent from the film, promoting the growth and crystallization of perovskite crystals. After annealing, the film is naturally cooled to room temperature, forming a dense and well-crystallized ferroelectric material-doped perovskite active layer on the surface of the SnO2 electron transport layer.

[0075] Carbon electrode preparation and battery assembly: Completely consistent with step (6) in Example 1, defining the effective working area as 0.071 cm². 2 After applying carbon paste and annealing for curing, FAPbBr3 system ferroelectric material modified perovskite solar cells are obtained.

[0076] Comparative Example 1

[0077] The preparation method of the perovskite solar cell described in this comparative example is completely consistent with that of Example 1, except for step (1) ferroelectric material preparation and step (4) dopant material replacement. The specific steps and process parameters are as follows:

[0078] (1) Preparation of ferroelectric comparative material (IBA)2(EA)Pb2Br7: Accurately weigh 12 mmol lead acetate trihydrate, 36 mmol ethylamine (EA), and 12 mmol isobutylamine (IBA), place them in a reaction flask, add 50 mL of 40% hydrobromic acid (HBr), heat and stir continuously until the yellow precipitate is completely dissolved to form a colorless and clear reaction system; keep the reaction system at 55℃, and slowly cool it down to 40℃ at a cooling rate of 0.5℃ / day to crystallize. After filtration and washing with isopropanol 3 times, the obtained crystals are placed in a vacuum drying oven at 60℃ and dried for 4 h to obtain (IBA)2(EA)Pb2Br7 ferroelectric material with clear ferroelectric properties for later use.

[0079] (2) Cleaning treatment of FTO conductive glass: Same as step (2) in Example 1.

[0080] (3) Preparation of SnO2 electron transport layer: consistent with step (3) of Example 1.

[0081] (4) Preparation of perovskite precursor solution: Except for replacing the doping material with (IBA)2(EA)Pb2Br7 prepared in step (1) and keeping the doping concentration unchanged, the other raw material ratios and preparation processes are the same as in step (4) of Example 1, and the corresponding doped perovskite precursor solution is obtained.

[0082] (5) Preparation of ferroelectric material doped perovskite active layer: consistent with step (5) of Example 1.

[0083] (6) Carbon electrode preparation and battery assembly: consistent with step (6) of Example 1, the target modified perovskite solar cell was finally prepared, and its photoelectric conversion efficiency (PCE) was tested to be 17.71%.

[0084] Comparative Example 2

[0085] The preparation method of the perovskite solar cell described in this comparative example is completely consistent with that of Example 1, except for step (1) ferroelectric material preparation and step (4) dopant material replacement. The specific steps and process parameters are as follows:

[0086] (1) Preparation of ferroelectric comparative material (Cl-PMA)2CsPb2Br7: Accurately weigh 2 mmol of lead acetate trihydrate and place it in a reaction flask. Slowly add 10 mL of 43% hydrobromic acid (HBr) and heat and stir until the raw material is completely dissolved. Then slowly add 1 mmol of cesium carbonate and 2 mmol of 4-chlorobenzylamine (Cl-PMA) solution to the solution and continue heating and stirring until the pale yellow precipitate is completely dissolved to form a clear reaction system. Place the container containing the solution in a 60℃ oven and slowly cool it at a rate of 1℃ / day to crystallize. After filtration and washing with isopropanol 3 times, the crystals are dried in a 60℃ vacuum drying oven for 4 h to obtain (Cl-PMA)2CsPb2Br7 ferroelectric material with clear ferroelectric properties for later use.

[0087] (2) Cleaning treatment of FTO conductive glass: Same as step (2) in Example 1.

[0088] (3) Preparation of SnO2 electron transport layer: consistent with step (3) of Example 1.

[0089] (4) Preparation of perovskite precursor solution: Except that the doping material is replaced with (Cl-PMA)2CsPb2Br7 prepared in step (1) and the doping concentration remains unchanged, the other raw material ratios and preparation processes are the same as in step (4) of Example 1, and the corresponding doped perovskite precursor solution is obtained.

[0090] (5) Preparation of ferroelectric material doped perovskite active layer: consistent with step (5) of Example 1.

[0091] (6) Carbon electrode preparation and battery assembly: consistent with step (6) of Example 1, the target modified perovskite solar cell was finally prepared, and its photoelectric conversion efficiency (PCE) was tested to be 18.67%.

[0092] Comparative Example 3

[0093] For FA 0.83 Cs 0.17 Based on Example 1, the PbI3 system was prepared without adding any modifying materials (neither BzCPB nor the two ferroelectric contrast materials). The remaining preparation steps were completely consistent with Example 1, yielding unmodified FA. 0.83 Cs 0.17 PbI3 system perovskite solar cells.

[0094] Comparative Example 4

[0095] For the FAPbBr3 system, based on Example 4, without adding BzCPB modifying material, the remaining preparation steps are completely consistent with Example 4, and an unmodified FAPbBr3 system perovskite solar cell is prepared.

[0096] Note: All blank control devices and reference devices were prepared in the same experimental environment as the corresponding examples to ensure consistent experimental conditions and reduce the interference of environmental factors on the experimental results. The effective working area of ​​all devices was 0.071 cm², consistent with Examples 1, 2, 1, 2, and 3.

[0097] Performance testing methods:

[0098] The devices of Examples 1-2 and Comparative Examples 1-4 were subjected to photoelectric performance tests and long-term stability tests, respectively, under the following specific test conditions:

[0099] (1) Photovoltaic performance test: A solar simulator (AM 1.5G, irradiance 100 mW / cm²) was used. 2 Under ambient temperature and pressure, the photoelectric conversion efficiency (PCE) and open-circuit voltage (V) of each device were tested. OC ), short-circuit current density (J SC ) and fill factor (FF).

[0100] (2) Long-term stability test: All devices were placed in an environment with a temperature of 18 to 28°C and a relative humidity of 45% to 65% RH without any packaging treatment and stored continuously for 2000 h. The efficiency retention rate was calculated (efficiency retention rate = PCE after storage / initial PCE × 100%) and the stability differences of different devices were compared.

[0101] Test results:

[0102] Figure 3 The infrared absorption spectra of the BzCPB ferroelectric material, perovskite (PVK), and BzCPB-doped perovskite composite system (sample with a BzCPB doping concentration of 0.03 mol%) prepared in Example 1 are shown. As can be seen from the figure, the infrared spectrum in the 600–800 cm⁻¹ range... -1 In this region, no obvious absorption peak was observed in the perovskite film. However, after the introduction of BzCPB, two new characteristic peaks appeared in this region, located at approximately 770.34 cm⁻¹. -1 and 718.12cm -1These two peaks can be attributed to the out-of-plane bending vibration of the C–H group on the benzene ring, and their peak positions are consistent with the characteristic absorption peaks of monosubstituted benzene. This proves that the benzylammonium cation in BzCPB has been successfully introduced into the perovskite film. Compared with the characteristic absorption peaks of monosubstituted benzene in pure BzCPB, these two new characteristic peaks are shifted to lower wavenumbers, indicating that there is a strong interfacial interaction between BzCPB and the perovskite inorganic framework.

[0103] Figure 4 The diagram shows the ferroelectric properties of the BzCPB ferroelectric material of this invention; where A is the ferroelectric hysteresis loop (PE) at 346 K, and B is the corresponding current-electric field (IE) curve. At 346 K, BzCPB exhibits a typical ferroelectric hysteresis loop, with a saturation polarization of 1.3 μC / cm² and a Curie temperature of 158 °C, further confirming that BzCPB possesses excellent ferroelectric properties. At 300 K, BzCPB belongs to the non-centrosymmetric Cmc21 space group, enabling it to construct an additional built-in electric field within the device and exert its ferroelectric modification effect.

[0104] Figure 5 The FA prepared in Example 1 is shown. 0.83 Cs 0.17 A comparison of the JV curves of the PbI3 ferroelectric modified battery (sample with BzCPB doping concentration of 0.03 mol%) with those of Comparative Example 1, Comparative Example 2, and blank control device (Comparative Example 3) clearly shows that the battery device modified with BzCPB in this invention has a significantly higher photoelectric conversion efficiency than the devices in Comparative Example 1, Comparative Example 2, and Comparative Example 3. This fully demonstrates the advantages of BzCPB ferroelectric modification and its ability to effectively improve the photoelectric conversion efficiency of the battery.

[0105] Figure 6 The efficiency retention of the battery device prepared in Example 1 (sample with a BzCPB doping concentration of 0.03 mol%) and two comparative devices after storage for 2000 h at a temperature of 18–28 °C and a relative humidity of 45%–65% RH is shown. The efficiency retention of the BzCPB-modified battery device of the present invention is significantly higher than that of the comparative devices, indicating that the introduction of BzCPB can effectively improve the stability of the perovskite active layer, reduce its decomposition and degradation, thereby improving the long-term stability of the battery and meeting the needs of practical applications.

[0106] Figure 7 The JV curves of the ferroelectric modified battery (sample with BzCPB doping concentration of 0.03 mol%) prepared in Example 2 and the blank control device (Comparative Example 4) are shown for comparison. Figure 7As can be seen, consistent with the results of Example 1, the PCE (7.15%) of the FAPbBr3 system battery modified with BzCPB is significantly higher than that of the comparative device modified with non-ferroelectric materials, proving that BzCPB can exert excellent ferroelectric modification effect in different perovskite systems and has good adaptability.

[0107] Comparative experimental results and analysis:

[0108] (1) Comparison of photoelectric performance results

[0109] As can be seen from Figures 5 and 7, whether it is FA 0.83 Cs 0.17 Whether using the PbI3 or FAPbBr3 system, devices modified with BzCPB ferroelectric material exhibit significantly higher photoelectric conversion efficiencies than the corresponding unmodified blank control devices; among them, FA... 0.83 Cs 0.17 In the PbI3 system, the photoelectric conversion efficiency of the BzCPB modified device is significantly higher than that of the reference devices in Comparative Examples 1, 2, and 3.

[0110] In specific analysis, FA 0.83 Cs 0.17 In the PbI3 system, the modified device achieved a PCE of 20.33%, a 30.57% improvement compared to the unmodified device (15.57%). In the FAPbBr3 system, the modified device achieved a PCE of 7.15%, a 20.3% improvement compared to the unmodified device (5.70%). This difference is mainly due to the ferroelectric properties of BzCPB: BzCPB has spontaneous polarization characteristics, which can build an additional built-in electric field inside the perovskite active layer, effectively promoting the separation of electrons and holes and reducing carrier recombination losses. At the same time, BzCPB forms hydrogen bonds with the perovskite active layer, which can passivate defects in the perovskite active layer and further reduce non-radiative recombination losses, thereby improving the photoelectric conversion efficiency of the device.

[0111] As shown in Figure 5, for FA 0.83 Cs 0.17The comparison results of the PbI3 system show that both ferroelectric comparative materials used in Comparative Examples 1 and 2 possess clear spontaneous polarization characteristics. Therefore, the photoelectric conversion efficiency of their modified devices is higher than that of the unmodified blank control device, showing an overall performance gradient of blank control device < (IBA)2(EA)Pb2Br7 modified device < (Cl-PMA)2CsPb2Br7 modified device < BzCPB modified device. Although the two ferroelectric comparative materials have similar two-dimensional perovskite chemical structures to BzCPB, due to the difference in the structure of organic amine cations, their bandgap matching, interface compatibility, and polarization field adaptability with the perovskite host system are inferior to those of BzCPB. They cannot construct an effective built-in electric field of the same strength as BzCPB, and their passivation ability for perovskite grain boundaries and surface defects is also significantly different. Therefore, their modification effect is significantly lower than that of the BzCPB modified device. The above results fully demonstrate that the ferroelectric properties of BzCPB, which are highly compatible with the perovskite system, are the core factor for achieving a significant improvement in the performance of perovskite solar cells, rather than simply the doping effect of organic amine groups or the ordinary ferroelectric effect.

[0112] (2) Results of long-term stability comparison

[0113] As shown in Figure 6, FA 0.83 Cs 0.17 In the PbI3 system, the long-term stability of the BzCPB-modified device was significantly higher than that of the reference devices modified with the two ferroelectric materials. After storage at room temperature and humidity for 2000 h, the FA... 0.83 Cs 0.17 The efficiency retention rate of the BzCPB-modified device in the PbI3 system can reach 91.2%, while the efficiency retention rate of the corresponding blank control device is only 71.8%.

[0114] Comparative experimental conclusions:

[0115] The comparative experiments above show that BzCPB ferroelectric materials are effective against both perovskite systems (FA). 0.83 Cs 0.17 Both PbI3 and FAPbBr3 exhibit excellent modification effects, enhancing the photoelectric conversion efficiency and long-term stability of perovskite solar cells. Among them, FA... 0.83 Cs 0.17 The comparative experiments on the PbI3 system fully demonstrate that its core modification advantage stems from the ferroelectric properties of BzCPB that are highly compatible with the perovskite system, rather than simple organic amine group doping or ordinary ferroelectric effect; the comparative experiments on the FAPbBr3 system further verify the universal modification effect of BzCPB in different perovskite systems.

[0116] While the two ferroelectric materials used in the comparison possess ferroelectric properties and similar chemical structures, their compatibility with the perovskite substrate is insufficient, preventing them from achieving equivalent improvements in device performance. Therefore, this invention employs BzCPB ferroelectric material as a modifier, effectively addressing the core pain points of low efficiency and poor stability in existing carbon-based perovskite solar cells, highlighting the innovation and practicality of this invention.

[0117] Furthermore, comparative experiments have demonstrated that the preparation process of this invention is simple and controllable, with good repeatability. Modified devices of both perovskite systems can achieve stable performance improvements, exhibit good adaptability, and are suitable for large-scale industrial production.

[0118] The cesium formamidinium lead halide-based perovskite materials in the above embodiments can also be other chemical formulas, such as FA. x Cs (1-x) PbI y Br (3-y) Other cesium formamidinium lead halide-based perovskite materials with different component ratios (0≤x≤1, 0≤y≤3); the electron transport layer can also be TiO2 or ZnO, both of which can achieve the purpose of this invention.

[0119] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A ferroelectric material-modified perovskite solar cell, characterized in that, It consists of a transparent conductive substrate, an electron transport layer, a perovskite active layer and a carbon electrode arranged sequentially. The active layer is prepared from a perovskite material doped with ferroelectric material (C6H5CH2NH3)2CsPb2Br7; the doping concentration of the ferroelectric material (C6H5CH2NH3)2CsPb2Br7 in the active layer is 0.01-0.05 mol%; the perovskite material is a cesium formamidinium lead halide-based perovskite material, wherein the halogen is selected from at least one of bromine and iodine, and its general chemical formula is FA. x Cs (1-x) PbI y Br (3-y) , where 0≤x≤1, 0≤y≤3.

2. The ferroelectric material-modified perovskite solar cell according to claim 1, characterized in that, The transparent conductive substrate is FTO or ITO.

3. The ferroelectric material-modified perovskite solar cell according to claim 1, characterized in that, The cesium carbamate lead halide-based perovskite material is described above. 0.83 Cs 0.17 PbI3 or FAPbBr3.

4. The ferroelectric material modified perovskite solar cell according to claim 1, characterized in that, The electron transport layer is SnO2, TiO2, or ZnO.

5. The ferroelectric material modified perovskite solar cell according to claim 1, characterized in that, The thickness of the active layer is 200-1000 nm; the thickness of the carbon electrode is 5-30 μm.

6. The method for preparing the ferroelectric material-modified perovskite solar cell according to any one of claims 1 to 5, characterized in that, Includes the following steps: Preparation of ferroelectric material (C6H5CH2NH3)2CsPb2Br7: Lead source, benzylamine source, cesium source and bromine source were weighed according to stoichiometric ratio and mixed. The mixture was heated and stirred until dissolved, cooled and crystallized to obtain ferroelectric material (C6H5CH2NH3)2CsPb2Br7. Clean the transparent conductive substrate; Prepare a SnO2 electron transport layer on a transparent conductive substrate; Ferroelectric material (C6H5CH2NH3)2CsPb2Br7 was added to the perovskite precursor solution, stirred evenly, and then spin-coated onto the surface of the SnO2 electron transport layer. After annealing, a ferroelectric material-doped perovskite active layer was formed. Carbon paste was coated onto the active layer and then annealed and cured to obtain a ferroelectric material modified perovskite solar cell.

7. The preparation method according to claim 6, characterized in that, The benzylamine source is a 99% pure benzylamine solution, the cesium source is cesium carbonate, and the bromine source is hydrobromic acid. When preparing the ferroelectric material (C6H5CH2NH3)2CsPb2Br7, the heating temperature is 75-85℃, the stirring time is 25-35 min, the cooling rate is 4-5℃ / h, and crystallization occurs when the temperature is lowered to room temperature.

8. The preparation method according to claim 6, characterized in that, The cleaning of the transparent conductive substrate specifically involves sequentially using glass cleaner, deionized water, and acetone as cleaning media, followed by ultrasonic cleaning and drying to complete the cleaning process.

9. The preparation method according to claim 6, characterized in that, When the cesium carbamate lead halide-based perovskite material is FA 0.83 Cs 0.17 For PbI3, the spin coating process for the active layer is as follows: spin coating at a speed of 4000-6000 rpm / s for 40-60 s; the annealing process parameters for the active layer are as follows: annealing at 100-150℃ for 10-15 min. When the cesium carbamate lead halide-based perovskite material is FAPbBr3, the spin coating process of the active layer is as follows: spin coating at a speed of 4000-6000 rpm / s for 40-60 s, and adding the anti-solvent ethyl acetate dropwise during the middle and later stages of spin coating; the annealing process parameters of the active layer are as follows: annealing at 100-150℃ for 30-40 min.

10. The application of the ferroelectric material modified perovskite solar cell according to any one of claims 1 to 5, characterized in that, It is used in the fields of photovoltaic power generation, power supply for portable electronic devices, and building-integrated photovoltaics.

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