Perovskite cell preparation method based on monofluorophenethyl bromide, cell and application

Abstract

The invention relates to a preparation method of a perovskite cell based on monofluorophenethyl bromide, the cell and application. The preparation method sequentially comprises the following steps: cleaning and pretreating ITO (Indium Tin Oxide) conductive glass; preparing a self-assembled monomolecular layer on the ITO conductive glass; preparing a perovskite light absorption layer on the self-assembled monomolecular layer; preparing a PI passivation layer on the perovskite light absorption layer; preparing a C60 electron transport layer on the PI passivation layer; preparing a SnO2 hole blocking layer on the C60 electron transport layer; and preparing an Ag metal electrode on the SnO2 hole barrier layer.

Description

Technical Field

[0001] This invention relates to the field of perovskite battery technology, and in particular to a method for preparing a perovskite battery based on monofluorophenylethyl bromide, the battery itself, and its applications. Background Technology

[0002] Perovskite solar cells (PSCs), as a next-generation photovoltaic technology, have attracted widespread attention from academia and industry in recent years due to their high photoelectric conversion efficiency, low-cost solution processing characteristics, and flexible fabrication capabilities. Since their first report in 2009, their certified efficiency has increased from 3.8% to over 27%, representing a significant breakthrough in the photovoltaic field. Perovskite materials typically have an ABX3 crystal structure, where A is an organic or inorganic cation (such as formamidinium ion FA). + methylamine ion MA + Cesium ions (Cs) + B is a divalent metal ion (such as Pb). 2+ Sn 2+ X is a halide anion (such as I). - ,Br - Cl - This unique crystal structure endows the material with excellent optoelectronic properties, including a high absorption coefficient, a long carrier diffusion length, and a tunable band gap.

[0003] However, perovskite solar cells still face three major challenges in their commercial application: efficiency loss, insufficient stability, and the difficulty of large-area fabrication. These challenges are essentially closely related to the defects of perovskite materials and devices: (1) Bulk and interface defects: Perovskite films are prone to various defects during solution processing, such as halogen vacancies, dangling bonds at metal sites, and lattice dislocations. These defects are mainly distributed at perovskite grain boundaries, surfaces, and interfaces with transport layers, becoming non-radiative recombination centers that significantly reduce the device open-circuit voltage (Voc) and fill factor (FF), thereby limiting the final efficiency. More importantly, these defects can also become channels for moisture and oxygen permeation and induce ion migration, leading to material degradation and performance decline.

[0004] (2) Stability issues: Perovskite materials are extremely sensitive to environmental factors (such as moisture, oxygen, heat, and light). Especially under high temperature, high humidity, or continuous light exposure, the perovskite structure is prone to phase separation, decomposition, and phase transformation. For example, the black phase α-CsPbI₂Br perovskite transforms into the non-photoactive yellow phase at room temperature. Although organic-inorganic hybrid perovskites are more efficient, their organic components (such as MA)... + FA + It has poor thermal stability and is prone to volatilization and decomposition at high temperatures.

[0005] (3) Large-area preparation problem: High efficiency in the laboratory is usually based on spin coating technology to prepare small areas (usually <0.1cm) under the inert atmosphere of a glove box. 2 While cells can be obtained through this process, when shifting to large-area modular fabrication, problems arise such as uneven film coverage, inconsistent crystal orientation, and a sharp increase in defect density. These problems are exacerbated, especially during fabrication in air, where variations in humidity and temperature further aggravate them, resulting in large-area modules having significantly lower efficiency than small cells, and exhibiting poor performance uniformity and repeatability.

[0006] The following is a brief description of approximate solutions in the prior art: Phenylethyl ammonium salts are among the most representative organic ammonium salts used for perovskite surface passivation, with phenylethyl ammonium iodide (PEAI) and phenylethyl ammonium bromide (PEABr) being the most extensively studied. These molecules typically consist of aromatic and ammonium groups, and their working mechanism mainly involves two aspects: (1) Surface passivation mechanism: Ammonium ions (-NH3) + ) through uncoordinated lead ions (Pb) on the perovskite surface 2+ The interaction between halogen vacancies and other halogen sites effectively passivates surface defects and reduces nonradiative recombination.

[0007] (2) Formation of low-dimensional perovskites: Due to the large size of phenylethylammonium ions, they cannot enter the interior of the three-dimensional perovskite lattice, but instead form a two-dimensional (2D) or quasi-two-dimensional perovskite capping layer on the surface. This structure can act as a physical barrier, inhibiting ion migration and blocking the intrusion of moisture and oxygen.

[0008] In summary, the shortcomings of the existing technical solutions can be briefly described as follows: While non-fluorinated PEAI or PEABr molecules offer some passivation, their passivation capabilities are relatively limited, primarily relying on the interactions of the ammonium groups. The limited hydrophobicity of the benzene ring and the lack of strong interaction sites with other components on the perovskite surface result in insufficient passivation of certain types of defects (such as halogen vacancies). Furthermore, energy level matching issues between the two-dimensional and three-dimensional phases can sometimes hinder charge transport, leading to a loss of fill factor.

[0009] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a perovskite battery preparation method, battery and application based on monofluorophenylethyl bromide, so as to make it more industrially valuable. Summary of the Invention

[0010] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a perovskite battery based on monofluorophenylethyl bromide, the battery itself, and its applications.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: One of the objectives of this invention is: A method for preparing perovskite solar cells based on monofluorophenylethyl bromide includes the following steps: Step 1: Cleaning and pretreatment of ITO conductive glass; Step 2: Prepare a self-assembled monolayer on ITO conductive glass; Step 3: Prepare a perovskite light-absorbing layer on a self-assembled monolayer; Step 4: Prepare a PI passivation layer on the perovskite light-absorbing layer; Step 5: Prepare C on the PI passivation layer 60 Electron transport layer; Step 6, in C 60 A SnO2 hole-blocking layer is prepared on the electron transport layer; Step 7: Prepare Ag metal electrodes on the SnO2 hole-blocking layer; The preparation of the perovskite light-absorbing layer in step S3 includes the following steps: Step S31: Add the monofluorophenylethyl bromide positional isomer as a dopant to the perovskite precursor solution. The monofluorophenylethyl bromide positional isomer is selected from at least one of 2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, and 4-fluorophenylethyl bromide. The doping concentration of the dopant in the perovskite precursor solution is 0.5~5 mol%. Step S32: The doped perovskite precursor solution is deposited on the substrate by spin coating to form a perovskite light-absorbing layer.

[0012] As a further improvement of the present invention, in step S31, the monofluorophenylethyl bromide positional isomer is 4-fluorophenylethyl bromide, and its doping concentration in the perovskite precursor solution is 2~3 mol.

[0013] As a further improvement of the present invention, step S32 includes the following steps in sequence: Step S321: Deposit the perovskite precursor solution using spin coating. The spin coating parameters are: rotation speed 4500~5500 rpm, acceleration 800~1200 rpm / s, and spin coating time 35~45 seconds. Step S322: 15-25 seconds after the spin coating begins, add 250-350 μL of chlorobenzene as an anti-solvent; Step S323: After spin coating, anneal the film at 95~105℃ for 18~22 minutes to form a perovskite light-absorbing layer.

[0014] As a further improvement of the present invention, in step 2, an ethanol solution of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid with a concentration of 0.4~0.6 mg / mL is used; spin coating is performed for 28~32 seconds at a rotation speed of 2500~3500 rpm and an acceleration of 2500~3500 rpm / s; after spin coating, the mixture is annealed at 80~120℃ for 8~12 minutes to form a self-assembled monolayer.

[0015] As a further improvement of the present invention, in step 4, an isopropanol solution of PI with a concentration of 0.3~0.5 mg / mL is used; the sample is spin-coated for 28~32 seconds at a rotation speed of 4500~5500 rpm and an acceleration of 800~1200 rpm / s; after spin-coating, the sample is annealed at 80~120℃ for 8~12 minutes to form a PI passivation layer.

[0016] As a further improvement of the present invention, in step 5, the vacuum degree is lower than 2.0 × 10⁻⁶. -3 Under the condition of Pa, at an evaporation rate of 0.1 Å / s, C with a thickness of 15~25 nm was deposited. 60 film.

[0017] As a further improvement of the present invention, in step 6, the cavity temperature is set to 80°C, and a tin source is sequentially introduced for 8-12 seconds, purged for 4-8 seconds, a water source is introduced for 8-12 seconds, and purged for 6-8 seconds, which constitutes one cycle. A total of 60-100 cycles are performed to form a SnO2 thin film with a thickness of 15-25 nm.

[0018] As a further improvement of the present invention, in step 7, a mask is used at a vacuum level below 6.0 × 10⁻⁶. -4 Step-rate evaporation under Pa conditions: Within the thickness range of 0–5 nm, the evaporation rate was controlled at 0.1 Å / s; Within the thickness range of 5–20 nm, the evaporation rate was controlled at 0.3 Å / s; Within the thickness range of 20–50 nm, the evaporation rate was controlled at 0.5 Å / s; Within a thickness range of 50–100 nm, the evaporation rate was controlled at 0.8 Å / s; The final Ag electrode has a thickness of 80~120nm.

[0019] The second objective of this invention is: A perovskite battery based on monofluorophenylethyl bromide is prepared by any of the methods described above.

[0020] The third objective of this invention: The application of a monofluorophenylethyl bromide positional isomer as a dopant in a perovskite precursor solution for the fabrication of perovskite solar cells, wherein the monofluorophenylethyl bromide positional isomer is selected from at least one of 2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide and 4-fluorophenylethyl bromide.

[0021] By means of the above-described solution, the present invention has at least the following advantages: This invention proposes a novel solution using monofluorophenylethyl bromide positional isomers (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, and 4-fluorophenylethyl bromide) as perovskite precursor dopants. The aim is to explore and utilize the differences in electronic and spatial effects resulting from the positional effects of fluorine atoms by introducing a single fluorine atom into the phenylethyl bromide molecule and systematically controlling its substitution position. Specifically: (1) Precise molecular design: Para-substitution (i.e. 4-fluorophenylethyl bromide) is the optimal choice because it can maximize the electronic effect to enhance passivation ability and has no steric hindrance problem.

[0022] (2) Synergistic passivation and protection: The strong electronegativity of fluorine atoms enhances the interaction with perovskite components (such as F…Pb, F…HN), while the excellent hydrophobicity of CF bonds is used to construct a superhydrophobic protective layer.

[0023] (3) Balancing performance and cost: Using simple and inexpensive monofluorinated molecules to achieve a balance between high performance and industrialization potential.

[0024] This invention solves the problems of blind design of passivating agents, difficulty in balancing efficiency and stability, and high cost of high-performance passivating agents in the prior art, and provides an efficient, stable and economical dopant option for the industrialization of perovskite solar cells.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following are preferred embodiments of the present invention described in detail with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic flowchart of a method for preparing a perovskite solar cell based on monofluorophenylethyl bromide according to the present invention. Figure 2This is a water contact angle test diagram of the perovskite thin films of the control group and the experimental group (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide and 4-fluorophenylethyl bromide) in the fourth embodiment of the present invention; Figure 3 This represents the highest photovoltaic performance of the perovskite single-junction devices in the control and experimental groups (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, and 4-fluorophenylethyl bromide) in the fourth embodiment of the present invention. JV Line graph. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] First embodiment of the present invention: This embodiment provides a method for preparing perovskite solar cells based on monofluorophenylethyl bromide, which aims to solve at least the following problems: First, it addresses the problem that existing dopant molecules are designed blindly and cannot accurately and synergistically passivate perovskite defects, resulting in significant losses in device open-circuit voltage and fill factor, making it difficult to further improve efficiency.

[0031] Second, it addresses the problem that the existing protective layers formed by doping and passivating agents are not hydrophobic and chemically stable enough to effectively resist the intrusion of moisture and oxygen and inhibit ion migration, thus leading to poor environmental and operational stability of perovskite solar cells.

[0032] Third, it addresses the problem that high-performance dopants and passivators often come with high costs and complex processes, which are not conducive to industrial applications.

[0033] like Figure 1 The present embodiment of a perovskite solar cell preparation method based on monofluorophenylethyl bromide includes the following steps in sequence: Step 1: Cleaning and pretreatment of ITO conductive glass.

[0034] The innovation of this step lies not in the cleaning itself, but in setting an "ultra-clean" substrate starting point for the subsequent preparation of high-quality self-assembled molecular (SAM) layers and perovskite layers. Its stringent standard of "two-cycle ultrasonic cleaning" (deionized water, anhydrous ethanol, repeated) ensures that there are no residual contaminants or ions on the substrate surface. This directly affects the regularity of the SAM layer and the nucleation density of the perovskite layer, representing a fundamental but crucial pretreatment innovation for achieving high-performance reproducibility.

[0035] Step 2: Prepare a self-assembled monolayer on ITO conductive glass.

[0036] In step 2, an ethanol solution of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid with a concentration of 0.4~0.6 mg / mL is used; spin coating is performed for 28~32 seconds at a rotation speed of 2500~3500 rpm and an acceleration of 2500~3500 rpm / s; after spin coating, the mixture is annealed at 80~120℃ for 8~12 minutes to form a self-assembled monolayer.

[0037] A self-assembled monolayer (SAM) was formed using a 4PADCB ethanol solution of a specific concentration (0.4–0.6 mg / mL) and specific spin-coating and annealing parameters. The innovation of this step lies in the fact that this SAM layer not only effectively extracts holes, but its specific molecular structure and surface energy also exhibit "molecular interface compatibility" with the subsequent perovskite precursor doped with 4-fluorophenylethyl bromide. This provides a template for the preferential orientation growth of perovskite crystals, a prerequisite for obtaining large-grained, low-defect perovskite films.

[0038] Step 3: Prepare a perovskite light-absorbing layer on a self-assembled monolayer.

[0039] The preparation of the perovskite light-absorbing layer in step S3 includes the following steps: Step S31: Add the monofluorophenylethyl bromide positional isomer as a dopant to the perovskite precursor solution. The monofluorophenylethyl bromide positional isomer is selected from at least one of 2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, and 4-fluorophenylethyl bromide. The doping concentration of the dopant in the perovskite precursor solution is 0.5~5 mol%. Step S32: The doped perovskite precursor solution is deposited on the substrate by spin coating to form a perovskite light-absorbing layer.

[0040] In step S31, the monofluorophenylethyl bromide positional isomer is 4-fluorophenylethyl bromide, and its doping concentration in the perovskite precursor solution is 2-3 mol.

[0041] Step S32 includes the following steps in sequence: Step S321: Deposit the perovskite precursor solution using spin coating. The spin coating parameters are: rotation speed 4500~5500 rpm, acceleration 800~1200 rpm / s, and spin coating time 35~45 seconds. Step S322: 15-25 seconds after the spin coating begins, add 250-350 μL of chlorobenzene as an anti-solvent; Step S323: After spin coating, anneal the film at 95~105℃ for 18~22 minutes to form a perovskite light-absorbing layer.

[0042] In step 3 above, the key point is: Molecular selection innovation: Abandoning traditional PEAI, PEABr or complex polyfluoro / trifluoromethyl molecules, we creatively select the positional isomers of monofluorophenylethyl bromide, and for the first time clearly define 4-fluorophenylethyl bromide (para-substituted) as the optimal choice.

[0043] Innovative application method: It is used as a precursor dopant (bulk phase doping) rather than a traditional post-treatment surface passivator. This means that the molecules intervene in the early stages of crystal growth, simultaneously regulating the crystallization process and passivating bulk phase and grain boundary defects.

[0044] Parameter synergistic innovation: The optimal doping concentration window (1.0~3.0 mol%, preferably 2.0 mol%) was determined. This concentration can maximize defect passivation and grain boundary control without destroying the three-dimensional perovskite main lattice.

[0045] Innovative process timing: The introduction of dopant is combined with a highly optimized spin-coating-antisolvent process (300 μchlorobenzene is added dropwise at 18-22 seconds). The addition of 4-fluorophenylethyl bromide alters the colloidal properties and crystallization kinetics of the precursor solution, making this antisolvent timing the most critical trigger point for obtaining bright, dense, pinhole-free films.

[0046] Step 4: Prepare a PI passivation layer on the perovskite light-absorbing layer.

[0047] In step 4, an isopropanol solution of PI with a concentration of 0.3~0.5 mg / mL is used; spin-coating is performed for 28~32 seconds at a rotation speed of 4500~5500 rpm and an acceleration of 800~1200 rpm / s; after spin-coating, the sample is annealed at 80~120℃ for 8~12 minutes to form a PI passivation layer.

[0048] On top of the innovative doped perovskite layer, post-passivation is performed using a specific concentration (0.4 mg / mL) of PI (perylene diimide) isopropanol solution. The innovation of this step lies in the fact that it is not an isolated passivation layer, but rather constitutes a "dual passivation strategy" with the bulk / grain boundary passivation already achieved in step S3. PI molecules can further passivate surface defects that were not fully covered in step S3, and their energy level matching with the optimized perovskite surface underneath is better, thereby minimizing interfacial recombination.

[0049] Step 5: Prepare C on the PI passivation layer 60 Electron transport layer.

[0050] In step 5, when the vacuum level is below 2.0 × 10⁻⁶ -3 Under the condition of Pa, at an evaporation rate of 0.1 Å / s, C with a thickness of 15~25 nm was deposited. 60 film.

[0051] Step 6, in C 60 A SnO2 hole-blocking layer was prepared on the electron transport layer.

[0052] In step 6, the cavity temperature is set to 80°C. A tin source is introduced for 8-12 seconds, then purged for 4-8 seconds, followed by a water source for 8-12 seconds and then purged for 6-8 seconds, which constitutes one cycle. A total of 60-100 cycles are performed to form a SnO2 thin film with a thickness of 15-25 nm.

[0053] In steps 5 and 6 above, in the inverted structure, thermal evaporation C is sequentially applied. 60 Together with atomic layer deposition (ALD) SnO2, it forms a highly efficient and stable "double insurance" structure for electron extraction and hole blocking.

[0054] Hot vapor deposition C 60 It can be applied to organic PI layers without damage.

[0055] SnO2 films grown using ALD technology are extremely dense and pinhole-free, perfectly blocking holes and preventing diffusion from metal electrodes.

[0056] This combination, together with the underlying perovskite light-absorbing layer (with improved energy levels after S3 optimization), creates an electron transport path with a smoother energy level gradient and fewer defects.

[0057] Step 7: Prepare Ag metal electrode on SnO2 hole blocking layer.

[0058] In step 7, a mask is used at a vacuum level below 6.0 × 10⁻⁶. -4 Step-rate evaporation under Pa conditions: Within the thickness range of 0–5 nm, the evaporation rate was controlled at 0.1 Å / s; Within the thickness range of 5–20 nm, the evaporation rate was controlled at 0.3 Å / s; Within the thickness range of 20–50 nm, the evaporation rate was controlled at 0.5 Å / s; Within a thickness range of 50–100 nm, the evaporation rate was controlled at 0.8 Å / s; The final Ag electrode has a thickness of 80~120nm.

[0059] An Ag electrode of a specific thickness (100 nm) was deposited using a step-rate evaporation (gradually increasing from 0.1 Å / s to 0.8 Å / s). The innovation of this method lies in the fact that the initial low rate helps to form a continuous and flat Ag core, while the subsequent high rate improves efficiency and ensures high conductivity and adhesion of the electrode, avoiding film cracking or poor contact caused by excessive internal stress, and ultimately ensuring the ohmic contact stability of the device under long-term operation.

[0060] A brief description of the synergistic effect in the above steps in this embodiment: 1. The order of substrate preparation, hole injection layer, and photoactive layer cannot be changed (steps 1 to 3). Technical rationale: Clean ITO (step 1) is required before a high-quality, ordered SAM hole injection layer can be formed on it (step 2). This SAM layer is the physical and energy level basis for the subsequent directional growth of perovskite (step 3) and efficient hole extraction. If the order is reversed (e.g., perovskite is prepared first), the SAM layer will fail to form, and the hole extraction efficiency will drop sharply.

[0061] Synergistic Creativity: The ultra-clean ITO substrate ensures the formation of a well-ordered SAM layer, which in turn synergizes with the 4-fluorophenylethyl bromide-doped perovskite precursor to guide the formation of a perovskite light-absorbing layer with excellent crystallinity and low defect density. These three interconnected steps lay the foundation for high-performance devices.

[0062] 2. The order of the photoactive layer, interface modification layer, and charge management layer cannot be changed (steps 3 to 6). Technical rationale: The PI passivation layer (step 4) must be directly fabricated on top of the perovskite light-absorbing layer (step 3) to effectively passivate residual defects on its surface. Electron transport layer (C 60 Step 5) must be prepared on top of the passivation layer, rather than in direct contact with the perovskite, to avoid PI and C in some cases. 60 The energy level mismatch problem, while PI can also protect the perovskite at C 60 To prevent damage during the vapor deposition process. The SnO2 hole-blocking layer (step 6) must be kept at C 60 Above this, electron extraction is completed and holes are blocked.

[0063] Synergistic Creativity: The perovskite optimized by bulk doping in step 3 exhibits more stable surface properties. Combined with the PI surface passivation in step 4, it achieves comprehensive defect management across the entire process from bulk phase to grain boundaries to the surface. This "dual passivation" structure, in conjunction with the "electron extraction-hole blocking" dual-insurance structure in steps 5 / 6, minimizes interfacial nonradiative recombination, thereby achieving a high open-circuit voltage (Voc) and a high fill factor (FF).

[0064] 3. Core Step: Step 3 serves as a "pivotal link between the preceding and following steps". Step 3 (preparation of the doped perovskite layer) is the creative embodiment and performance amplifier of this scheme.

[0065] Continuing from above: It relies on the good growth template provided in step 2.

[0066] The high-quality, low-defect, energy-optimized perovskite films it produces maximize the efficiency of the subsequent passivation layer in step 4 and the charge management layer in steps 5 / 6.

[0067] In summary, this embodiment aims to provide a series of doping and passivating agent molecules (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, 4-fluorophenylethyl bromide), and to identify the para-substitution structure (4-fluorophenylethyl bromide) as the optimal choice, so as to achieve a synergistic improvement in the efficiency and stability of perovskite solar cells. At the same time, it provides clear theoretical guidance for their molecular design and meets the cost requirements for future large-scale production.

[0068] The second embodiment of the present invention: This embodiment describes a perovskite battery based on monofluorophenylethyl bromide, which is prepared by any of the methods described above.

[0069] The third embodiment of the present invention: This embodiment describes the application of a monofluorophenylethyl bromide positional isomer as a dopant in a perovskite precursor solution for the fabrication of perovskite solar cells. The monofluorophenylethyl bromide positional isomer is selected from at least one of 2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, and 4-fluorophenylethyl bromide.

[0070] Fourth embodiment of the present invention: This embodiment of a perovskite solar cell preparation method based on monofluorophenylethyl bromide includes the following steps in sequence: (1) Cleaning of ITO conductive glass Take a number of pre-etched pieces, each measuring 2.5 x 2.5 cm, as needed. 2For ITO conductive glass, gently rub both sides of the glass several times with a lint-free cloth soaked in glass cleaning solution, then rinse thoroughly with deionized water. Place the conductive glass on a glass cleaning rack and put it in a beaker of appropriate size. Add deionized water to cover the glass sample, wrap the mouth of the beaker with clean aluminum foil, and place it in an ultrasonic cleaner for 15 minutes. After that, replace it with anhydrous ethanol and ultrasonically clean for 15 minutes. Repeat the above ultrasonic steps once. Use a dry air gun to blow the ITO glass evenly until it is dry before use.

[0071] (2) Preparation of self-assembled monolayers (SAM layers) Preparation of 4PADCB solution: Weigh a certain amount of 4PADCB solid powder into a weighing bottle in a nitrogen glove box, dissolve it in a certain amount of anhydrous ethanol using a pipette, and stir on a stirrer for about 1 hour to form a 0.5 mg / mL 4PADCB solution. Use a UV cleaner to irradiate the sample treated in step (1) with UV light for 15 min and transfer it to a nitrogen glove box. Use a spin coater to vacuum adsorb the glass, and use a pipette to drop 90 μL of 4PADCB solution onto the ITO conductive surface. The spin coater speed is 3000 rpm, the acceleration is 3000 rpm / s, and the spin coat time is 30 s. Start the spin coater to perform the spin coat operation. After the spin coat is completed, use tweezers to pick up the glass slide and place it on the heating stage for annealing. The annealing temperature is 100℃ and the annealing time is 10 min to form a self-assembled monolayer. (3) Preparation of perovskite light-absorbing layer Preparation of the control group perovskite precursor solution: Weigh a certain amount of PbI2, PbBr2, FAI, MACl, PbCl2 and CsI solid powders into a weighing bottle in a nitrogen glove box. Dissolve them in a certain amount of DMF and DMSO solvent (VDMF:VDMSO=8:2) using a pipette. Shake the solution on a shaker for more than 3 hours. Then filter the solution using a 0.22μm PTFE filter to form a 1.4M control group perovskite solution for later use.

[0072] Preparation of perovskite precursor solution for experimental group: Unlike the control group, 0.5~5 mol% of 4-fluorophenylethyl bromide (or 2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide) was added to the perovskite precursor solution of the experimental group, and the doped perovskite solution was thoroughly shaken and mixed to form the perovskite solution of the experimental group.

[0073] The perovskite layer was prepared in a nitrogen glove box. The sample treated in step (2) was vacuum adsorbed using a spin coater, and 100 μL of perovskite precursor solution was dropped onto the self-assembled layer using a pipette. Spin coating was performed with parameters of 5000 rpm spin speed, 1000 rpm / s acceleration, and 40 s spin coating time. The spin coater was started for spin coating operation. At the 20th second of spin coating, 300 μL of chlorobenzene anti-solvent was flushed down. After spin coating, the sample was picked up with tweezers and placed on a heating stage for annealing. The annealing temperature was 100℃ and the annealing time was 20 min to form a perovskite light-absorbing layer.

[0074] (4) Preparation of passivation layer Preparation of PI passivation solution: Weigh a certain amount of PI solid powder into a weighing bottle in a nitrogen glove box, dissolve it in a certain amount of isopropanol solvent using a pipette, and stir on a stirrer for more than 6 hours to form a PI passivating agent solution with a concentration of 0.4 mg / mL. Use a spin coater to vacuum adsorb the sample treated in step (3), and use a pipette to drop 60 μL of PI passivation solution onto the perovskite film. The spin coating speed is 5000 rpm, the acceleration is 1000 rpm / s, and the spin coating time is 30 s. Start the spin coater to perform the spin coating operation. After the spin coating is completed, use tweezers to pick up the glass slide and place it on the heating stage for annealing. The annealing temperature is 100℃ and the annealing time is 10 min to form a passivation layer.

[0075] (5) Fabrication of electron transport layer The sample completed in step (4) is then used to prepare C using a vapor deposition device. 60 Electron transport layer, when the vacuum level of the device cavity drops to 2.0 × 10⁻⁶. -3 Below Pa, evaporation was carried out at a rate of 0.1 Å / s for 20 nm, then stopped, to obtain C. 60 Electron transport layer.

[0076] (6) Preparation of hole blocking layer After step (5) is completed, SnO2 hole blocking layer is prepared using an atomic layer deposition device. The chamber temperature is set to 80°C. The tin source is passed through for 10s, then purged for 6s, the water source is passed through for 10s, and then purged for 8s. Each of the above passing and purging steps is counted as one cycle. After a total of 80 cycles, the formation of a 20nm thick tin dioxide hole blocking layer is stopped.

[0077] (7) Preparation of metal electrodes Based on step (6), use a scraper to remove approximately 3-4 mm of film from both ends of the sample, exposing approximately 3 mm of the bottom ITO layer, which will serve as the deposition electrode area. Place the prepared sample on a custom-patterned mask and put it into the deposition chamber. Evaporate the air to reduce the vacuum level to 6.0 × 10⁻⁶. -4Evaporation begins below Pa. The evaporation process employs a staged rate evaporation method: the rate is controlled at approximately 0.1 Å / s in the 0~5 nm range, approximately 0.3 Å / s in the 5~20 nm range, approximately 0.5 Å / s in the 20 nm~50 nm range, and approximately 0.8 Å / s in the 50~100 nm range, forming an Ag electrode with a thickness of 100 nm.

[0078] After completing all the above steps, the single-junction wide-bandgap perovskite solar cell is fabricated, with a device structure of ITO / / SAM / PVK / PI / C. 60 / SnO2 / Ag can be used for performance testing.

[0079] The core of this embodiment lies in the first-time discovery and application of the decisive influence of fluorine atom substitution position on the behavior and passivation mechanism of neutral phenethyl bromide molecules in perovskites, thereby achieving precise and efficient passivation of perovskite defects and improved stability. These three isomers, due to the different positions of their fluorine atoms, exhibit significant differences in electronic and steric effects, resulting in drastically different properties.

[0080] like Figure 2 The water contact angle test diagrams of the perovskite films of the control group and experimental group (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide and 4-fluorophenylethyl bromide) in this embodiment are shown. The larger the water droplet angle, the better the hydrophobicity of the film, which can bring good long-term stability.

[0081] 4-Fluorophenylethyl bromide (para position) is the best performing of the three due to its perfect electronic effect and irreplaceable synergistic passivation ability. 2-Fluorophenylethyl bromide (ortho position) is the worst performing control due to severe steric hindrance. 3-Fluorophenylethyl bromide (meta position) has performance in between.

[0082] like Figure 3 The highest photovoltaic performance of the perovskite single-junction devices in the control group and experimental group (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide and 4-fluorophenylethyl bromide) shown in this embodiment is illustrated. JV Line graph.

[0083] Table 1 shows the average photovoltaic performance of perovskite single-junction devices in the control group and experimental group (2-fluorophenylethyl bromide, 3-fluorophenylethyl bromide, 3-fluorophenylethyl bromide) in this embodiment (12 devices each): Table 1 shows the average photovoltaic performance parameters of the control group and the three experimental groups, including open-circuit voltage ( ). V OC ), short-circuit current density ( J SC ), fill factor (FF) and photoelectric conversion efficiency (PCE).

[0084] 1. Performance ranking (based on reverse scan PCE) Rank 1: 4-Fluorophenylethyl bromide (23.00%) 2nd place: 3-Fluorophenylethyl bromide (21.51%) 3rd Place: Control Group (20.84%) 4th place: 2-Fluorophenylethyl bromide (18.31%) 2. Comparison and analysis of various parameters 1) Open circuit voltage ( V OC ) 4-Fluorophenylethyl bromide (1.24 V) > 3-Fluorophenylethyl bromide (1.23 V) > Control group (1.21 V) > 2-Fluorophenylethyl bromide (1.18 V) Analysis: VOC directly reflects the degree of nonradiative recombination in a device. 4-Fluorophenylethyl bromide exhibits the highest VOC, demonstrating its superior defect passivation effect and ability to most effectively suppress charge recombination. The VOC of 2-fluorophenylethyl bromide is even lower than the control group, indicating that its steric hindrance may have introduced new defects or hindered effective passivation.

[0085] 2) Short-circuit current density ( J SC ) 4-Fluorophenylethyl bromide (21.97 mA / cm) 2 )>3-Fluorophenylethyl bromide (21.22 mA / cm 2 > Control group (21.11mA / cm) 2 )>2-Fluorophenylethyl bromide (20.63 mA / cm) 2 ) Analysis: JSC is related to the charge generation and collection efficiency of the device. The 4-fluorophenylethyl bromide group has the highest JSC, indicating that the perovskite thin film prepared by it is of better quality and has fewer defects, and may have improved charge transport, enabling more photogenerated carriers to be effectively collected.

[0086] 3) Fill factor (FF) 4-Fluorophenylethyl bromide (84.44%) > 3-Fluorophenylethyl bromide (82.43%) > Control group (81.65%) > 2-Fluorophenylethyl bromide (75.23%) Analysis: FF measures the series and parallel resistance of a device. 4-Fluorophenylethyl bromide achieves the highest FF, indicating the lowest series resistance and smoothest charge transport. This is attributed to its excellent thin film quality, optimized energy level alignment, and minimal interfacial recombination. The FF of 2-fluorophenylethyl bromide drops sharply, likely due to its large steric hindrance severely hindering charge transport across grain boundaries, leading to a significant increase in series resistance.

[0087] 4) Photoelectric conversion efficiency (PCE) 4-Fluorophenylethyl bromide improved the average efficiency from 20.84% ​​in the control group to 23.00%, with an absolute efficiency increase of up to 2.16%, which is a very significant improvement.

[0088] 3-Fluorophenylethyl bromide also provides some improvement, but the effect is far less than that of para-substitution.

[0089] 2-Fluorophenylethyl bromide had a negative impact on performance, with efficiency lower than the control group.

[0090] 3. Hysteresis Analysis of Forward and Reverse Scans All devices exhibited higher reverse scanning efficiencies than forward scanning efficiencies, a common phenomenon in perovskite solar cells. However, it is noteworthy that the difference between the forward and reverse scanning data for the 4-fluorophenylethyl bromide group was relatively small (22.22% vs 23.00%), indicating that ion migration within the device was somewhat suppressed, potentially resulting in better stability.

[0091] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0092] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite cell based on monofluorophenethyl bromide, characterized in that, Comprise the following steps in sequence: Step 1, cleaning and pretreatment of ITO conductive glass; Step 2, preparing a self-assembled monolayer on the ITO conductive glass; Step 3, preparing a perovskite light-absorbing layer on the self-assembled monolayer; Step 4, preparing a PI passivation layer on the perovskite light-absorbing layer; Step 5, preparing C on the PI passivation layer 60 electron transport layer Step 6, preparing a SnO2 hole blocking layer on the C 60 an electron transport layer, and a SnO2 hole blocking layer. Step 7, preparing an Ag metal electrode on the SnO2 hole-blocking layer; In step S3, the preparation of the perovskite light-absorbing layer comprises the following steps in sequence: Step S31, adding a monofluorophenethyl bromine positional isomer as a dopant to a perovskite precursor solution, the monofluorophenethyl bromine positional isomer being selected from at least one of 2-fluorophenethyl bromine, 3-fluorophenethyl bromine and 4-fluorophenethyl bromine, and the doping concentration of the dopant in the perovskite precursor solution being 0.5-5 mol%; Step S32, depositing the doped perovskite precursor solution on a substrate by a spin coating method to form a perovskite light-absorbing layer.

2. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, In the step S31, the monofluorophenethyl bromine positional isomer is 4-fluorophenethyl bromine, and the doping concentration thereof in the perovskite precursor solution is 2-3 mol%.

3. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, The step S32 comprises the following steps in sequence: Step S321, depositing the perovskite precursor solution by a spin coating method, and the spin coating parameters being: rotation speed 4500-5500 rpm, acceleration 800-1200 rpm / s, and spin coating time 35-45 seconds; Step S322, at 15-25 seconds after the start of spin coating, dropping 250-350 μL of chlorobenzene as an anti-solvent; Step S323, after the end of spin coating, annealing the film at 95-105°C for 18-22 minutes to form a perovskite light-absorbing layer.

4. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, In the step 2, an ethanol solution of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid with a concentration of 0.4-0.6 mg / mL is used; the rotation speed is 2500-3500 rpm, the acceleration is 2500-3500 rpm / s, and the spin coating time is 28-32 seconds; and after the end of spin coating, annealing at 80-120°C for 8-12 minutes to form a self-assembled monolayer.

5. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, In the step 4, an isopropanol solution of PI with a concentration of 0.3-0.5 mg / mL is used; the rotation speed is 4500-5500 rpm, the acceleration is 800-1200 rpm / s, and the spin coating time is 28-32 seconds; and after the end of spin coating, annealing the sample at 80-120°C for 8-12 minutes to form a PI passivation layer.

6. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, In the step 5, the C thin film with the thickness of 15-25 nm is deposited at the evaporation rate of 0.1 Å / s under the condition that the vacuum degree is less than 2.0 x 10 -3 Pa. 60 thin film.

7. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized in that, In the step 6, the cavity temperature is set to 80°C, tin source is introduced for 8-12 seconds, purged for 4-8 seconds, water source is introduced for 8-12 seconds, and purged for 6-8 seconds for one cycle, a total of 60-100 cycles are performed to form a SnO2 film with a thickness of 15-25 nm.

8. A monofluorophenethyl bromide-based perovskite cell preparation method according to claim 1, characterized by, In the step 7, the step rate evaporation is performed using a mask plate under the condition that the vacuum degree is less than 6.0 x 10 -4 Pa: In the thickness interval of 0-5 nm, the evaporation rate is controlled at 0.1 Å / s; In the thickness interval of 5-20 nm, the evaporation rate is controlled at 0.3 Å / s; In the thickness interval of 20-50 nm, the evaporation rate is controlled at 0.5 Å / s; In the thickness interval of 50-100 nm, the evaporation rate is controlled at 0.8 Å / s; Finally, an Ag electrode with a thickness of 80-120 nm is formed.

9. A perovskite cell based on mono-fluorophenethyl bromide, characterized in that, Prepared by the process of any one of claims 1-8.

10. Use of a monofluorophenethyl bromide regioisomer as a dopant in a perovskite precursor solution, characterized in that, For use in the preparation of perovskite solar cells, the monofluorophenethyl bromide regioisomers are selected from at least one of 2-fluorophenethyl bromide, 3-fluorophenethyl bromide, and 4-fluorophenethyl bromide.

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