Fluorine-substituted benzimidazolyl aniline compound as well as synthesis method and application thereof

Abstract

The invention relates to the technical field of organic photoelectric materials and photovoltaic devices, in particular to a fluorine-substituted benzimidazolyl aniline compound and a synthesis method and application thereof. The structural general formula of the compounds is as shown in a formula I in the specification. The compound is introduced into a perovskite precursor solution as an additive and is used for preparing a perovskite thin film and a trans-perovskite solar cell. According to the compound provided by the invention, synergistic passivation of multi-site defects such as uncoordinated Pb < 2 + > and iodine vacancies is realized through aniline amino and benzimidazole ring N atoms in molecules, and non-radiative recombination is remarkably reduced; the strong electronegativity of fluorine atoms can enhance the electrostatic interaction between molecules and a perovskite Pb-I skeleton, meanwhile, a large conjugated system promotes pi-pi accumulation, and experimental results show that the photoelectric conversion efficiency of a champion device based on the additive can reach 23.3%; .

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials and photovoltaic devices, specifically to a fluorinated benzimidazole aniline compound, and also to a method for preparing the compound and its application as an additive in perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs) have become a core research direction in next-generation photovoltaic technology due to their outstanding advantages such as high photoelectric conversion efficiency, low manufacturing cost, and excellent solution processability. To date, the laboratory photoelectric conversion efficiency (PCE) of perovskite solar cells has exceeded 26%, approaching the efficiency level of traditional crystalline silicon cells, demonstrating enormous commercial potential. However, the structural instability of perovskite materials themselves and the non-radiative recombination caused by numerous defects within the device remain the core bottlenecks restricting their large-scale industrial application.

[0003] During the fabrication of perovskite light-absorbing layers (such as formamidinium lead iodide and cesium formamidinium lead iodide), numerous defects are easily generated due to inhomogeneous crystallization kinetics and incomplete lattice coordination. These defects mainly include uncoordinated Pb²⁺, iodine vacancies (Vᵢ⁻), and cation vacancies in the bulk phase, as well as dangling bond defects at grain boundaries and surfaces. These defects significantly accelerate the nonradiative recombination of photogenerated electron-hole pairs, reduce carrier lifetime, and consequently lead to lower open-circuit voltage (Voc) and fill factor (FF) of the device. At the same time, defect sites are also weak points for moisture erosion and ion migration. Under actual working environments such as light, humidity, and high temperature, they can easily induce phase separation, hydrolysis, and thermal decomposition of perovskite materials, leading to rapid degradation of device efficiency.

[0004] To address the aforementioned issues, additive engineering has been widely adopted as a simple and efficient modification strategy. By introducing specific functionalized small organic molecule additives into the perovskite precursor solution, precise passivation of defects can be achieved, while simultaneously regulating the perovskite crystallization process, thereby improving the film crystallization quality and environmental stability. Among these, aniline compounds, due to the ability of their amino groups (-NH2) to form stable coordination bonds with uncoordinated Pb²⁺, have become an important class of perovskite defect passivation additives.

[0005] In the prior art, reported aniline additives include 2,4-dichloroaniline, triphenylamine derivatives, and cyano-substituted anilines. For example, Chinese patent CN114864325A discloses 2,4-dichloroaniline as a perovskite precursor additive, which passivates Pb²⁺ defects through amino coordination and enhances the interaction between chlorine atoms and the perovskite framework; Chinese patent CN115312783A discloses a cyano-containing triphenylamine derivative, which utilizes the strong electron-withdrawing properties of cyano groups to improve passivation efficiency. However, existing aniline additives still have significant shortcomings: First, they have limited functional groups, which can only passivate single types of defects and cannot comprehensively repair defects at multiple sites such as bulk, grain boundaries, and surfaces. Second, the interaction between the molecules and the perovskite lattice is weak, making them prone to desorption during long-term device operation, leading to a decrease in passivation effect. Third, their hydrophobicity is generally insufficient, making it difficult to effectively resist the corrosion of perovskite materials by humid environments. Fourth, some compounds have unreasonable conjugated structures, resulting in poor energy level matching with perovskite and affecting charge transport efficiency.

[0006] Benzimidazole heterocyclic compounds possess stable fused-ring conjugated structures, strong intramolecular electron transfer capabilities, and excellent hydrophobicity. The nitrogen atom in the imidazole ring of these molecules provides additional coordination sites. Fluorine atoms, due to their strong electronegativity and high hydrophobicity, not only further enhance the defect passivation ability of the molecule but also significantly improve the compound's moisture resistance and thermal stability. Introducing fluorine atoms into the molecular skeleton of benzimidazole-based aniline compounds to construct fluorinated benzimidazole-based aniline compounds (with the substituents limited to hydrogen or fluorine, and at least one being fluorine) imparts multiple synergistic effects to the molecule: "amino group + imidazole ring nitrogen atom + fluorine atom." This allows for multi-site defect passivation through the amino group and the imidazole ring nitrogen atom, while the strong electronegativity of the fluorine atom enhances the interaction with the perovskite lattice and improves hydrophobicity. Currently, there are no reports on the use of this type of fluorinated compound as an additive for perovskite solar cells. Therefore, developing novel fluorinated benzimidazole aniline compounds that combine high efficiency passivation and high stability is of great significance for improving the efficiency and stability of perovskite solar cells. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing aniline-based perovskite additives, such as single passivation sites, weak lattice bonding, insufficient hydrophobicity, and poor stability. This invention provides a fluorinated benzimidazole-based aniline compound (R1-R4 are hydrogen or fluorine, and at least one is fluorine). This compound has a unique structure of "aniline amino-benzimidazole fused ring-fluorine substituent," which simultaneously achieves synergistic passivation of multiple defect sites and high stability protection. Furthermore, this invention provides a method for preparing this compound and its application in perovskite solar cells, achieving a simultaneous improvement in the photoelectric conversion efficiency and long-term stability of perovskite solar cells.

[0008] The specific technical solution provided by this invention is as follows: In a first aspect, the present invention provides a fluorinated benzimidazole aniline compound having the general structural formula shown in Formula I: ; R1, R2, R3, and R4 are independently selected from hydrogen atoms or fluorine atoms, and at least one of R1, R2, R3, and R4 is a fluorine atom.

[0009] The carbon atom at position 2 of the benzimidazole ring is connected to the para position of the aniline benzene ring via a C-C single bond; the benzene ring portion of the benzimidazole ring has 0 to 4 substituents R1, R2, R3, R4, each of which is independently selected from -H or -F; and at least one of R1, R2, R3, R4 is -F; the nitrogen atom at position 1 of the benzimidazole ring has an -NH- structure.

[0010] This compound achieves targeting of uncoordinated Pb through the aniline amino group and the nitrogen atom of the benzimidazole ring in the molecule. 2+ Synergistic passivation of defects at multiple sites, such as iodine vacancies, significantly reduces nonradiative recombination; the strong electronegativity of fluorine atoms can enhance the electrostatic interaction between the molecule and the perovskite Pb-I framework, while the large conjugated system promotes π-π stacking.

[0011] Preferably, the fluorinated benzimidazolyl aniline compound has any of the following structures: .

[0012] The synthesis process of the fluorinated benzimidazole aniline compounds of the present invention is characterized by mild reaction conditions and simple steps, specifically including the following steps: Using the compounds shown in Formula 1 and Formula 2 as raw materials, the compounds were dissolved in N,N-dimethylformamide at room temperature and subjected to a cyclization reaction in the presence of a catalyst to obtain the compound shown in Formula 3. Using the compounds shown in Formula 3 and Formula 4 as raw materials, a substitution reaction was carried out under the action of a catalyst to obtain the compound shown in Formula 5; Using the compound shown in Formula 5 as a raw material, a reduction reaction was carried out to obtain the benzimidazole aniline compound shown in Formula 6; The synthetic route is as follows: ; R1, R2, R3, and R4 are independently selected from hydrogen atoms or fluorine atoms, and at least one of R1, R2, R3, and R4 is a fluorine atom.

[0013] Preferably, the molar ratio of the compound shown in Formula 1 to the compound shown in Formula 2 is 1:10~25, and the molar ratio of the compound shown in Formula 3 to the compound shown in Formula 4 is 1:2~10.

[0014] Preferably, the cyclization reaction is carried out under nitrogen protection at 80-110°C for 2-8 hours; The substitution reaction was carried out under nitrogen protection at 120-180°C for 15-20 h. The reduction reaction was carried out under nitrogen protection at 60-90°C for 3-5 hours.

[0015] In a third aspect, the present invention provides the application of fluorinated benzimidazole aniline compounds in perovskite solar cells.

[0016] The fluorine-substituted benzimidazole aniline compounds of the present invention are introduced as additives into the perovskite precursor solution, which are compatible with various perovskite solar cell structures such as inverted solar cells. The specific application steps are as follows: (1) Preparation of perovskite precursor solution: FA was prepared by dissolving 228.4 mg FAI, 18.2 mg CsI, and 645.4 mg PbI2 in a mixed solvent solution (v / v, DMF:DMSO = 4:1). 0.95 Cs 0.05 The PbI3 perovskite solution was prepared by shaking N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1 for 3 hours at room temperature. Before spin coating, the solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane to obtain the perovskite precursor mixture.

[0017] (2) Preparation of additive-doped precursor solution: The basic precursor solution cooled to room temperature was transferred to a nitrogen glove box, and the Pb content in the perovskite precursor was adjusted accordingly. 2+ Add 0.5-3% molar amount of the fluorinated benzimidazole aniline compound powder of the present invention, shake for 15 minutes to ensure complete dissolution of the compound, and obtain an additive-doped perovskite precursor solution. (3) Preparation of perovskite thin films: Substrate pretreatment: A clean conductive substrate was treated with a UV ozone cleaner for 15 minutes to remove surface organic impurities. NiO was then prepared. xThe hole transport layer was dissolved in high-purity H2O at a concentration of 2.5–20 mg / mL, sonicated for 5 minutes, and then spin-coated for 20 seconds at 3000 rpm with a 0.22 μm hydrophilic filter (PES) through water. After annealing at 100–150 °C for 10 minutes, the hole transport layer was prepared by mixing Me-4PACz with anhydrous ethanol to obtain a hole transport layer solution with a concentration of 0.5 mg / mL. 100 μL of the coating solution was pipetted onto the bottom electrode and spin-coated at 3000 rpm for 30 seconds. After spin-coating, the solution was annealed on a hot plate at 100 °C for 10 minutes and then allowed to cool naturally to obtain the hole transport layer.

[0018] Spin-coating film formation: The additive-doped perovskite precursor solution is uniformly drop-coated onto the pretreated substrate surface using a two-step spin-coating process: first, spin-coating at 1000~2000 rpm for 10 seconds (ensuring uniform coverage of the substrate), and then spin-coating at 3000~5000 rpm for 30 seconds; 8 seconds before the end of spin-coating, 100~200 μL of chlorobenzene is dropped onto the edge of the substrate as an anti-solvent to promote rapid crystallization of the perovskite; Annealing treatment: The spin-coated substrate is immediately placed on a hot stage at 100~130℃ for annealing for 10~20 minutes, and then naturally cooled to room temperature to obtain a dense, pinhole-free, highly crystalline perovskite film. (4) Assembly of perovskite solar cells: Inverse battery assembly (ITO / NiO) x / Perovskite / Electron Transport Layer / Electrode): An electron transport layer (C60 and BCP) is deposited on the surface of the perovskite thin film; then an Ag electrode (100~120 nm thick) is deposited. Device encapsulation: The prepared battery device is encapsulated with UV-curable adhesive to avoid external moisture and oxygen corrosion, resulting in the finished perovskite solar cell.

[0019] Preferably, based on the Pb content in the perovskite precursor 2+ Add 1-2% of the fluorinated benzimidazole aniline compound powder by molar amount.

[0020] In a fourth aspect, the present invention provides a perovskite thin film prepared according to the steps described above, specifically: Prepare perovskite precursor solution; The fluorinated benzimidazole aniline compound was added to the precursor solution to obtain a doped perovskite precursor solution. The doped precursor solution was spin-coated onto the surface of a conductive substrate and annealed at 100-130°C for 10-20 minutes to obtain a perovskite thin film.

[0021] Preferably, the perovskite precursor solution is prepared by dissolving the perovskite raw material in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 to form a solution with a concentration of 1.2~1.5 mol / L. The amount of the fluorinated benzimidazole aniline compound added is 0.5-3% of the molar amount of Pb²⁺ in the perovskite precursor; The spin coating process is as follows: first spin coating at 1000~2000 rpm for 5~10 seconds, then spin coating at 3000~5000 rpm for 20~30 seconds; The heat treatment is performed at a temperature of 100~130℃ for 10~20 minutes.

[0022] In a fifth aspect, the present invention provides a perovskite solar cell comprising the surface of the perovskite thin film.

[0023] Preferably, the perovskite solar cell has an inverted structure, comprising, in sequence, an ITO / FTO conductive glass, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, and an electrode.

[0024] The fluorinated benzimidazole aniline compounds provided by this invention significantly improve the performance of perovskite solar cells through a triple synergistic effect of "multi-site defect passivation - strong lattice bonding - fluorine-enhanced hydrophobic protection". The specific mechanism is as follows: 1. Precise passivation at multiple sites: The aniline amino (-NH2) N atom in the compound molecule has strong electron-donating properties, and its lone pair electrons can interact with uncoordinated Pb atoms in the perovskite lattice. 2+ Forming stable coordination bonds effectively eliminates Pb 2+ Dangling bond defects; simultaneously, the two N atoms on the benzimidazole ring, due to their high electronegativity, can fill iodine vacancies in the perovskite lattice through electrostatic adsorption (Vᵢ). - The presence of cation and anion defects allows for the simultaneous passivation of cation and anion defects, significantly reducing non-radiative recombination centers. 2. Fluorine enhances lattice bonding: The strong electronegativity of fluorine atoms can bond with Pb in the perovskite lattice. 2+ The compound exhibits additional electrostatic attraction, while the "benzimidazole fused ring-aniline benzene ring" structure forms a large π-conjugated system, creating a strong π-π stacking interaction with the Pb-I octahedral framework of the perovskite. This dual effect significantly enhances the bonding strength between the molecule and the perovskite lattice, inhibiting desorption during long-term device operation. Furthermore, the introduction of fluorine atoms can regulate perovskite crystallization kinetics, promoting perovskite grain growth (increasing grain size from hundreds of nanometers to over 2 μm), reducing grain boundaries, and minimizing grain boundary recombination losses. Secondary ion mass spectrometry analysis confirms that the iodine ion diffusion coefficient is reduced to 8 × 10⁻⁶. -15 cm 2Below / s, it effectively suppresses ion migration; 3. High-efficiency hydrophobic protection and improved stability: Fluorine atoms have extremely strong hydrophobicity, and the compound molecules can form a dense "fluorine-based protective layer" on the surface of the perovskite film, which significantly reduces the water vapor intrusion rate (the water contact angle is increased from 75° to over 115°). At the same time, the strong interaction between fluorine atoms and the perovskite lattice can further improve the thermal stability of perovskite, inhibit the transformation of α-FAPbI3 to the non-photovoltaic active δ phase at high temperatures, and fluorine atoms can also inhibit the hydrolysis reaction of perovskite materials, extending the service life of devices.

[0025] Compared with the prior art, the fluorinated benzimidazole aniline compounds of the present invention and their applications have the following significant advantages: 4. More efficient and comprehensive passivation function: Breaking through the limitations of existing single-function additives, it achieves passivation of uncoordinated Pb through the multiple synergistic effects of "amino + imidazole ring N atom + fluorine atom". 2+ Simultaneous and efficient passivation of multiple defects such as iodine vacancies and cation vacancies can increase the defect state density of perovskite thin films from 1×10⁻⁶. 15 cm -3 Reduced to 3×10 13 cm -3 The non-radiative recombination loss is reduced by more than 90% below; 5. Efficiency Breakthrough: The perovskite solar cell based on the compound of this invention can achieve a photoelectric conversion efficiency (PCE) of over 23%, with the champion device reaching a PCE of 23.3% (open-circuit voltage V). OC 1.13 V, short-circuit current density J SC 25.91 mA / cm², fill factor FF 79.43%); 6. Simple preparation process and low cost: The preparation of the compound only requires two basic chemical raw materials, fluorinated o-phenylenediamine and fluorinated p-aminobenzoic acid, which can be completed through a one-step condensation reaction without the need for complex functional group modification or expensive catalysts; the product purification only requires recrystallization, which is easy to scale up production, and the raw material cost is less than 80,000 yuan / ton. 7. Good industrial compatibility: The compound is easily soluble in commonly used solvents for perovskite precursors, and the addition amount is small (0.5-5%), which will not destroy the perovskite lattice structure; its doping and thin film preparation process is fully compatible with existing industrial technologies such as solution spin coating and annealing, without the need for large-scale modification of the production line, and can be directly used for performance upgrades of existing perovskite battery production lines. 5. High structural tunability: By controlling the fluorine substitution sites and substitution amounts (monofluorine, difluorine), the solubility, energy level structure and hydrophobicity of compounds can be flexibly controlled, adapting to the modification needs of perovskites with different components (formamidinyl, cesiumyl, mixed cationic groups), and has a wide range of applications. Attached Figure Description

[0026] Figure 1 : Schematic diagram of the inverse perovskite solar cell structure based on the compound of this invention; Figure 2 Comparison of JV characteristic curves of inverted perovskite solar cells in Examples 1 and 3 and Comparative Examples 1 and 2.

[0027] Figure 3 Mass spectrum of compound 1.

[0028] Figure 4 : Mass spectrum of compound 2.

[0029] Figure 5 : Mass spectrum of compound 3.

[0030] Figure 6 Mass spectrum of compound 4.

[0031] Figure 7 Mass spectrum of compound 5.

[0032] Figure 8 Mass spectrum of compound 6.

[0033] Figure 9 Mass spectrum of compound 7.

[0034] Figure 10 : Mass spectrum of compound 8. Detailed Implementation

[0035] The present invention will be further described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0036] Example 1 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 4-fluoro-1H-benzimidazole (2 g, 14.69 mmol), 4-nitroiodobenzene (7.32 g, 29.38 mmol), palladium acetate (0.16 g, 0.73 mmol), and cuprous iodide (5.60 g, 29.38 mmol) were placed in a reaction flask, purged with nitrogen, and 15 ml of N,N-dimethylformamide was injected into the flask using a syringe. The reaction mixture was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, the mixture was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the product was separated by column chromatography. The product yield was 67.74% (2.56 g). The synthetic route is as follows: Synthesis of S2, Compound 1: Intermediate 1 (2 g, 7.78 mmol) was dissolved in 10 mL of ethanol solution. Iron powder (1.74 g, 31.12 mmol) and 2 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 58.29% (1.03 g). The synthetic route is as follows:

[0037] .

[0038] The mass spectrometry results of compound 1 are as follows: Figure 3 As shown.

[0039] Example 2 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 5-fluoro-1H-benzo[D]imidazole (2 g, 14.69 mmol), 4-nitroiodobenzene (7.32 g, 29.38 mmol), palladium acetate (0.16 g, 0.73 mmol), and cuprous iodide (5.60 g, 29.38 mmol) were placed in a reaction flask, purged with nitrogen, and 15 ml of N,N-dimethylformamide was injected into the flask using a syringe. The reaction solution was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, the reaction solution was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the reaction product was separated by column chromatography. The product yield was 77% (2.91 g). The synthetic route is as follows: Synthesis of S2, Compound 2: Intermediate 1 (2 g, 7.78 mmol) was dissolved in 10 mL of ethanol solution, and iron powder (1.74 g, 31.12 mmol) and 2 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 69.05% (1.22 g). The synthetic route is as follows:

[0040] The mass spectrometry results of compound 2 are as follows: Figure 4 As shown.

[0041] Example 3 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 6,7-Difluoro-1H-benzo[d]imidazole (2 g, 12.98 mmol), 4-nitroiodobenzene (6.46 g, 25.95 mmol), palladium acetate (0.15 g, 0.65 mmol), and cuprous iodide (4.94 g, 25.96 mmol) were placed in a reaction flask, purged with nitrogen, and 15 ml of N,N-dimethylformamide was injected into the flask using a syringe. The reaction mixture was reacted at 120 °C for 20 h under nitrogen protection. The reaction was then stopped, cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred for 0.5 h under open conditions, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the product was separated by column chromatography. The product yield was 75.88% (2.71 g). The synthetic route is as follows: Synthesis of S2 and Compound 3: Intermediate 1 (2 g, 7.27 mmol) was dissolved in 10 mL of ethanol solution, and iron powder (1.62 g, 29.08 mmol) and 2 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 90 °C for 3 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 71.26% (1.27 g). The synthetic route is as follows:

[0042] The mass spectrometry results of compound 3 are as follows: Figure 5 As shown.

[0043] Example 4 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 4,6-Difluoro-1H-benzo[d]imidazole (1 g, 6.49 mmol), 4-nitroiodobenzene (3.23 g, 12.98 mmol), palladium acetate (0.08 g, 0.33 mmol), and cuprous iodide (2.47 g, 14.22 mmol) were placed in a reaction flask, purged with nitrogen, and 10 ml of N,N-dimethylformamide was injected into the flask using a syringe. The reaction mixture was reacted at 180 °C for 15 h under nitrogen protection. The reaction was then stopped, cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the product was separated by column chromatography. The product yield was 59.36% (1.06 g). The synthetic route is as follows: Synthesis of S2 and Compound 4: Intermediate 1 (1 g, 3.63 mmol) was dissolved in 10 mL of ethanol solution, and iron powder (0.81 g, 14.54 mmol) and 1 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 72.95% (0.65 g). The synthetic route is as follows:

[0044] The mass spectrometry results of compound 4 are as follows Figure 6 As shown.

[0045] It should be noted that 4-fluoro-1H-benzimidazole, 5-fluoro-1H-benzi[D]imidazole, 6,7-difluoro-1H-benzi[d]imidazole, and 4,6-difluoro-1H-benzi[d]imidazole in Examples 1 to 4 are all readily available for purchase, therefore their preparation methods are not described in detail in the above examples.

[0046] Example 5 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 3,6-Difluoro-1,2-diaminobenzene (2 g, 13.88 mmol) was dissolved in 10 mL of formic acid and refluxed at 100 °C for 4 h. The reaction solution was concentrated under vacuum, and the concentrated mixture was poured into 30 mL of water. A 10% sodium hydroxide solution was added dropwise to neutralize the system, and the pH was adjusted to 7. The precipitate was collected by filtration, dried, and recrystallized using a water-acetonitrile mixed solvent (volume ratio 1:1) to obtain the product. The product yield was 72.47% (1.55 g). The synthetic route is as follows: Synthesis of S2, Intermediate 2: Intermediate 1 (1.5 g, 9.73 mmol), 4-nitroiodobenzene (4.85 g, 19.47 mmol), palladium acetate (0.12 g, 0.50 mmol), and cuprous iodide (3.71 g, 21.33 mmol) were placed in a reaction flask, and the atmosphere was purged with nitrogen. 15 ml of N,N-dimethylformamide was injected into the reaction flask using a syringe. The reaction mixture was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, and the mixture was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The product was then separated by column chromatography, with a yield of 48.16% (1.29 g). The synthetic route is as follows: Synthesis of S2 and Compound 5: Intermediate 2 (1 g, 3.63 mmol) was dissolved in 10 mL of ethanol solution, and iron powder (0.81 g, 14.54 mmol) and 1 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 75.19% (0.67 g). The synthetic route is as follows:

[0047] The mass spectrometry results of compound 5 are as follows: Figure 7 As shown.

[0048] Example 6 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 3,4,5-trifluoro-1,2-diaminobenzene (5 g, 30.84 mmol) was dissolved in 12 ml formic acid and refluxed at 100 °C for 4 h. The reaction solution was concentrated under vacuum, and the concentrated mixture was poured into 50 ml of water. 10% sodium hydroxide solution was added dropwise to neutralize the system and adjust the pH to 7. The precipitate was collected by filtration, dried, and recrystallized using a water-acetonitrile mixed solvent (volume ratio 1:1) to obtain the product. The product yield was 76.86% (4.08 g). The synthetic route is as follows: Synthesis of S2, Intermediate 2: Intermediate 1 (3 g, 17.43 mmol), 4-nitroiodobenzene (8.68 g, 34.86 mmol), palladium acetate (0.2 g, 0.87 mmol), and cuprous iodide (6.64 g, 34.86 mmol) were placed in a reaction flask, and the atmosphere was purged with nitrogen. 15 ml of N,N-dimethylformamide was injected into the reaction flask using a syringe. The reaction solution was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, and the reaction solution was cooled to room temperature. Ethyl acetate was added for dilution, and the solution was poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred under open conditions for 0.5 h, and then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The reaction product was then separated by column chromatography. The product yield was 72.98% (3.73 g). The synthetic route is as follows: Synthesis of S3, Compound 6: Intermediate 2 (3 g, 10.23 mmol) was dissolved in 15 mL of ethanol solution, and iron powder (2.29 g, 40.92 mmol) and 3 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 63.86% (1.72 g). The synthetic route is as follows:

[0049] The mass spectrometry results of compound 6 are as follows: Figure 8 As shown.

[0050] Example 7 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 3,4,6-trifluoro-1,2-diaminobenzene (5 g, 30.84 mmol) was dissolved in 30 mL of formic acid and refluxed at 80 °C for 8 h. The reaction solution was concentrated under vacuum, and the concentrated mixture was poured into 50 mL of water. A 10% sodium hydroxide solution was added dropwise to neutralize the system, and the pH was adjusted to 7. The precipitate was collected by filtration, dried, and recrystallized using a water-acetonitrile mixed solvent (volume ratio 1:1) to obtain the product. The product yield was 68.01% (3.61 g). The synthetic route is as follows: Synthesis of S2, Intermediate 2: Intermediate 1 (3 g, 17.43 mmol), 4-nitroiodobenzene (8.68 g, 34.86 mmol), palladium acetate (0.2 g, 0.87 mmol), and cuprous iodide (6.64 g, 34.86 mmol) were placed in a reaction flask, and the atmosphere was purged with nitrogen. 15 ml of N,N-dimethylformamide was injected into the reaction flask using a syringe. The reaction mixture was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, and the mixture was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The product was then separated by column chromatography, with a yield of 64.94% (3.19 g). The synthetic route is as follows: Synthesis of S3, Compound 7: Intermediate 2 (3 g, 10.23 mmol) was dissolved in 15 mL of ethanol solution, and iron powder (2.29 g, 40.92 mmol) and 3 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 72.03% (1.94 g). The synthetic route is as follows:

[0051] The mass spectrometry results of compound 7 are as follows: Figure 9As shown.

[0052] Example 8 A fluorinated benzimidazolyl aniline compound, the molecular structural formula of which is: The preparation method of the above compound includes the following steps: Synthesis of S1, Intermediate 1: 3,4,5,6-Tetrafluorophenyl-1,2-diamine (2 g, 11.10 mmol) was dissolved in 5 ml formic acid and refluxed at 110 °C for 2 h. The reaction solution was concentrated under vacuum, and the concentrated mixture was poured into 50 ml of water. A 10% sodium hydroxide solution was added dropwise to neutralize the system, and the pH was adjusted to 7. The precipitate was collected by filtration, dried, and recrystallized using a water-acetonitrile mixed solvent (volume ratio 1:1) to obtain the product. The product yield was 72.00% (1.52 g). The synthetic route is as follows: Synthesis of S2, Intermediate 2: Intermediate 1 (1.5 g, 7.89 mmol), 4-nitroiodobenzene (19.65 g, 78.9 mmol), palladium acetate (0.09 g, 0.39 mmol), and cuprous iodide (3.00 g, 15.78 mmol) were placed in a reaction flask, and the atmosphere was purged with nitrogen. 5 ml of N,N-dimethylformamide was injected into the reaction flask using a syringe. The reaction mixture was reacted at 140 °C for 16 h under nitrogen protection. The reaction was then stopped, and the mixture was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium chloride aqueous solution. The resulting mixture was stirred in an open container for 0.5 h, then extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The product was then separated by column chromatography, with a yield of 68.42% (1.68 g). The synthetic route is as follows: Synthesis of S3, Compound 8: Intermediate 2 (1.5 g, 10.23 mmol) was dissolved in 15 mL of ethanol solution, and iron powder (2.29 g, 40.92 mmol) and 1.5 mL of hydrochloric acid solution were added. Under nitrogen protection, the mixture was heated to reflux at 60 °C for 5 h, and then the reaction was stopped. The mixture was cooled to room temperature, and the resulting suspension was diluted with ethyl acetate. Sodium hydroxide solution was then added dropwise until the system became alkaline. The organic and aqueous phases were separated. The aqueous phase was extracted twice with ethyl acetate. All organic phases were combined and washed with saturated brine. The combined organic phases were dried over anhydrous sodium sulfate. The dried organic phase was filtered, and the filtrate was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain the product with a yield of 58.28% (0.79 g). The synthetic route is as follows:

[0053] The mass spectrometry results of compound 8 are as follows: Figure 10 As shown.

[0054] Since compounds with the expected effects of the present invention were prepared in Examples 1 to 8, the effects of the compounds prepared in Examples 2 and 8 will be described below.

[0055] Application Example 1 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline S1. Prepare FA by dissolving 228.4 mg FAI, 18.2 mg CsI, and 645.4 mg PbI2 in a mixed solvent solution (v / v, DMF: DMSO = 4:1). 0.95 Cs 0.05 PbI3 perovskite solution; S2. After cooling the basic precursor solution to room temperature, transfer it to a nitrogen glove box, add 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline (0.014 mmol, 0.0034 g, which is 1% of the molar amount of Pb²⁺) prepared in Example 2, and shake for 15 minutes (power 120 W) to obtain the additive-doped perovskite precursor solution; S3, Take ITO / NiO x After the substrate (2 cm × 2 cm) was cleaned with UV ozone for 15 minutes, 50 μL of the above precursor solution was dropped onto the substrate surface and a two-step spin coating process was adopted: spin coating at 1500 rpm for 8 seconds, spin coating at 4000 rpm for 25 seconds, and 150 μL of chlorobenzene was dropped 5 seconds before the end of spin coating. S4. Immediately after spin coating, the substrate is placed on a hot table at 120°C for annealing for 15 minutes. After cooling, a perovskite film is obtained, which serves as the perovskite light-absorbing layer.

[0056] S5. Dissolve phenylethylamine iodide (PEAI) in isopropanol to prepare a passivation solution with a concentration of 1 mg / mL. Spin-coat the solution onto the substrate surface at 3000 rpm for 30 seconds, and immediately place it on a heating stage to anneal at 100°C for 10 minutes to form an interface passivation layer on the surface of the perovskite light-absorbing layer.

[0057] Application Example 2 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S2, which is as follows: After cooling the basic precursor solution to room temperature, it was transferred to a nitrogen glove box, and 0.42 mmol (0.0102 g) of 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline (Pb) prepared in Example 2 was added. 2+ Additive-doped perovskite precursor solution was obtained by shaking for 15 minutes (120 W power) with 3% molar amount of the solution.

[0058] Application Example 3 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S2, which is as follows: After cooling the basic precursor solution to room temperature, it was transferred to a nitrogen glove box, and 0.007 mmol (0.0017 g) of 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline (Pb) prepared in Example 2 was added. 2+ Additive-doped perovskite precursor solution was obtained by shaking for 15 minutes (120 W power) with 0.5% molar amount of the solution.

[0059] Application Example 4 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S3, which is as follows: Take ITO / NiO x After the substrate (2 cm × 2 cm) was cleaned with UV ozone for 15 minutes, 50 μL of the above precursor solution was dropped onto the substrate surface using a two-step spin coating process: spin coating at 1000 rpm for 10 seconds, spin coating at 3000 rpm for 30 seconds, and 150 μL of chlorobenzene was added 5 seconds before the end of spin coating.

[0060] Application Example 5 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S3, which is as follows: Take ITO / NiO x After the substrate (2 cm × 2 cm) was cleaned with UV ozone for 15 minutes, 50 μL of the above precursor solution was dropped onto the substrate surface using a two-step spin coating process: spin coating at 2000 rpm for 5 seconds, spin coating at 5000 rpm for 20 seconds, and 150 μL of chlorobenzene was dropped 5 seconds before the end of spin coating.

[0061] Application Example 6 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S4, which is as follows: Immediately after spin coating, the substrate is placed on a 100°C hot plate for annealing for 20 minutes.

[0062] Application Example 7 Preparation of perovskite precursor solutions and thin film fabrication based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline The only difference from Application Example 1 is step S4, which is as follows: Immediately after spin coating, the substrate is placed on a 130°C hot plate for annealing for 10 minutes.

[0063] Since the perovskite thin films with the expected effects of the present invention were all prepared in Application Examples 1 to 7, the following description of the preparation and effects of the inverted perovskite solar cell will only take the perovskite thin film prepared in Application Example 1 as an example.

[0064] Application Example 8 Assembly and performance testing of trans-perovskite solar cells based on 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline S1. On the surface of the perovskite thin film prepared in Application Example 1, under a vacuum of 5 × 10⁻⁶... -4 C60 25nm and BCP 6nm were deposited at Pa at a deposition rate of 0.1 nm / s. S2, at a vacuum degree of 5×10 -4 An Ag electrode (110 nm thick) was deposited at Pa at a deposition rate of 0.1 nm / s and an electrode area of ​​0.09 cm². S3. Encapsulate the device with UV-curable adhesive to obtain an inverted perovskite solar cell, the structural schematic of which is shown in the figure below. Figure 1 As shown.

[0065] Performance testing: The JV curve of the device was measured using a Keithley 2400 source meter under AM 1.5G simulated sunlight (100 mW / cm²) at a scan rate of 0.1 V / s.

[0066] The results showed: PCE 23.3%, V OC 1.13V, J s c 25.91mA / cm 2 FF 0.79; Application Example 9 Assembly and performance testing of inverted perovskite solar cells based on 4-(5-fluoro-1H-benzo[d]imidazol-2-yl)-2-fluoroaniline Except for S2, the remaining processes are the same as in Application Example 1. The compound prepared in Example 8 is used as the perovskite additive material. The compound prepared in Example 8 is mixed with the perovskite precursor solution to obtain a coating solution with an additive concentration of 0.8 mg / mL. The initial PCE of the device is 23.13% (V). OC 1.14V, J SC 25.36 mA / cm 2 ,FF 0.79).

[0067] Comparative Example 1 Inverse perovskite solar cells without additives Except for the absence of the addition of the fluorinated benzimidazole aniline compound of the present invention to the perovskite precursor solution, the preparation steps were exactly the same as in Application Example 1; the initial PCE of the device was 21.96% (V). OC 1.05 V, J SC 25.95mA / cm 2 ,FF0.75).

[0068] Comparative Example 2 Trans-perovskite solar cells using non-fluorinated benzimidazolylaniline to replace the compounds of this invention The 4-(5,6-difluoro-1H-benzo[d]imidazol-2-yl)aniline in Application Example 1 was replaced with 4-(1H-benzo[d]imidazol-2-yl)aniline (fluorine-free substitution), and the remaining preparation steps were exactly the same as in Application Example 1; the initial PCE of the device was 22.71% (V). OC 1.13 V, J SC 26.24 mA / cm², FF 0.77).

[0069] The performance test results of the batteries used in Examples 8 and 9 and Comparative Examples 1 and 2 are shown in Table 1.

[0070] Table 1 Performance of the perovskite solar cell of the present invention As can be seen from the comparison of application examples 8 and 9 with comparative examples 1 and 2, the fluorinated benzimidazole aniline compounds of the present invention, as additives for trans-perovskite solar cells, have significantly better performance than devices without additives, those modified with traditional 2,4-dichloroaniline, and those modified with non-fluorinated benzimidazole aniline. They can achieve a simultaneous and significant improvement in photoelectric conversion efficiency and environmental stability, and have obvious comprehensive performance advantages.

Claims

1. A fluorinated benzimidazolyl aniline compound, characterized in that, Its general structural formula is shown in Formula I: ； R1, R2, R3, and R4 are independently selected from hydrogen atoms or fluorine atoms, and at least one of R1, R2, R3, and R4 is a fluorine atom.

2. The fluorinated benzimidazole aniline compound according to claim 1, characterized in that, The fluorinated benzimidazole aniline compounds have any of the following structures: 。 3. A method for synthesizing the fluorinated benzimidazole aniline compound of claim 1, characterized in that, Includes the following steps: Using the compounds shown in Formula 1 and Formula 2 as raw materials, a cyclization reaction was carried out in the presence of a catalyst to obtain the compound shown in Formula 3; Using the compounds shown in Formula 3 and Formula 4 as raw materials, a substitution reaction was carried out under the action of a catalyst to obtain the compound shown in Formula 5. Using the compound shown in Formula 5 as a starting material, a reduction reaction was carried out to obtain the benzimidazole aniline compound shown in Formula 6; The synthetic route is as follows: ； R1, R2, R3, and R4 are independently selected from hydrogen atoms or fluorine atoms, and at least one of R1, R2, R3, and R4 is a fluorine atom.

4. The synthesis method according to claim 3, characterized in that, The molar ratio of the compound shown in Formula 1 to the compound shown in Formula 2 is 1:10~25, and the molar ratio of the compound shown in Formula 3 to the compound shown in Formula 4 is 1:2~10.

5. The synthesis method according to claim 3, characterized in that, The cyclization reaction was carried out under nitrogen protection at 80-110°C for 2-8 hours. The substitution reaction was carried out under nitrogen protection at 120-180°C for 15-20 h. The reduction reaction was carried out under nitrogen protection at 60-90°C for 3-5 hours.

6. The application of a fluorinated benzimidazole aniline compound as described in claim 1 or 2 in a trans-perovskite solar cell, characterized in that, The fluorinated benzimidazole aniline compounds are introduced as additives into the perovskite precursor solution for the preparation of perovskite thin films and inverted perovskite solar cells.

7. A perovskite thin film, characterized in that, It is prepared according to the following steps: Prepare perovskite precursor solution; Add the fluorinated benzimidazole aniline compound of claim 1 or 2 to the precursor solution to obtain a doped perovskite precursor solution; The doped precursor solution was spin-coated onto the surface of a conductive substrate, and then heat-treated to obtain a perovskite thin film.

8. The perovskite thin film according to claim 7, characterized in that, The perovskite precursor solution is prepared by dissolving the perovskite raw material in a mixed solvent of DMF and DMSO at a volume ratio of 4:1 to form a solution with a concentration of 1.2~1.5 mol / L. The amount of the fluorinated benzimidazole aniline compound added is 0.5-3% of the molar amount of Pb²⁺ in the perovskite precursor; The spin coating process is as follows: first spin coating at 1000~2000 rpm for 5~10 seconds, then spin coating at 3000~5000 rpm for 20~30 seconds; The heat treatment is performed at a temperature of 100-130°C for 10-20 minutes.

9. A perovskite solar cell, characterized in that, Includes the perovskite thin film as described in claim 7 or 8.

10. The perovskite solar cell according to claim 9, characterized in that, The perovskite solar cell has an inverted structure and includes, in sequence, an ITO / FTO conductive glass, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, and an electrode.

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