A passivation agent for passivating a perovskite thin film layer, a preparation method and application thereof

Abstract

The present application relates to the technical fields of photoelectric material and perovskite solar cell, and particularly relates to a passivation agent for passivating perovskite thin film layer, a preparation method and application. The structural general formula of the passivation agent for passivating perovskite thin film layer is: wherein X is selected from halogen atoms or CH3. The passivation agent for passivating perovskite thin film layer can be a high-efficiency passivation agent for perovskite thin film, can precisely passivate defects in the perovskite thin film, optimize the interface energy level arrangement, improve the carrier transport efficiency, and significantly enhance the thermal stability and wet stability of the perovskite solar cell device. Different from the conventional para-substitution or long-chain connection type carbazole derivatives, the passivation structure of unilateral substitution and single phenolic hydroxyl group is adopted in the present application, and the problems existing in the prior art are solved, thereby providing a new technical path for defect passivation of perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials and perovskite solar cell technology, specifically to a passivating agent for passivating perovskite thin film layers, its preparation method, and its application. Background Technology

[0002] Perovskite solar cells, with their excellent photoelectric conversion performance and low-cost solution processing characteristics, have become a research hotspot for next-generation photovoltaic technology. Currently, the photoelectric conversion efficiency (PCE) of small-area devices in the laboratory has exceeded 26%, demonstrating broad prospects for industrialization. However, during the solution preparation process of perovskite thin films, a large number of lattice defects easily appear, mainly including uncoordinated Pb. 2+ Cation defects, halide ions (I - ,Br - Vacancy defects and dangling bond defects at grain boundaries are problematic. These defects exacerbate nonradiative recombination of charge carriers, hinder interfacial charge transport, and exacerbate ion migration, thus limiting the improvement of photoelectric conversion efficiency. At the same time, defect sites easily become channels for water and oxygen erosion, leading to the degradation of perovskite films and significantly reducing the long-term stability of devices. This is the core bottleneck currently facing the industrialization process of perovskite solar cells.

[0003] To address the aforementioned shortcomings, existing technologies have developed various passivating agents for the modification of perovskite films, which can be mainly categorized as follows: (1) Ammonium salt passivating agents (such as PEAI and FAI): passivation is achieved by combining ammonium ions with halogen vacancies. However, these passivating agents are prone to introducing ionic impurities and have poor hydrophobicity, making them unable to effectively block water and oxygen erosion, resulting in limited improvement in long-term stability; (2) Pyridine and imidazole derivatives: passivation is achieved by coordinating uncoordinated Pb with nitrogen atoms. 2+ However, these molecules have insufficient conjugation and weak carrier transport ability, and most of them are single-function passivators, which cannot solve the problems of defect passivation and interface energy level matching at the same time; (3) Phenolic small molecule passivators: through hydroxyl groups and Pb 2+ Coordination achieves passivation, but the molecular structure is simple, the hydrophobicity is poor, the thermal stability is insufficient, and it is easy to desorb from the perovskite surface, and the passivation effect lasts for a short time; (4) Carbazole derivatives: Carbazole groups have good conjugation, hydrophobicity and thermal stability, and have been used in the hole transport layer of perovskite batteries. However, most of the currently disclosed carbazole molecules are para-substituted structures, which have problems such as easy molecular aggregation, poor interface compatibility and single passivation site. They cannot achieve precise passivation of defects and it is difficult to achieve a synergistic improvement in efficiency and stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a passivating agent for perovskite thin films, its preparation method, and its application. The passivating agent for perovskite thin films of this invention has a carbazole-phenol backbone, with a single-sided substituent (methyl, fluorine, chlorine, or bromine) and a single phenolic hydroxyl group on the benzene ring. It exhibits excellent conjugation, hydrophobicity, and thermal stability, and its molecular energy level is highly matched to the perovskite active layer, enabling simultaneous carrier transport and defect passivation. When applied to perovskite solar cells, it utilizes a synergistic passivation mechanism of single-sided substitution and a single phenolic hydroxyl group, specifically, the phenolic hydroxyl group targets and coordinates uncoordinated Pb. 2+ The steric hindrance effect inhibits molecular aggregation and optimizes interface stacking, effectively solving the problems of existing passivating agents such as single function, insufficient hydrophobicity, energy level mismatch, complex synthesis, and easy aggregation and poor interface compatibility of carbazole derivatives. It achieves precise passivation of dual defects of anions and cations, significantly suppresses nonradiative recombination of charge carriers, and improves the photoelectric conversion efficiency, fill factor and long-term thermal and humid stability of the device.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to provide a passivating agent for perovskite thin films, the general structural formula of which is: , where X is selected from halogen atoms or CH3.

[0006] Preferably, X is selected from F, Cl, Br or CH3.

[0007] Preferably, the passivating agent for the perovskite thin film layer is selected from... , , or .

[0008] A second objective of this invention is to provide a method for preparing the passivating agent for the above-mentioned passivated perovskite thin film layer, comprising the following steps: S1. Using 2-methoxy-3-X-phenyl halide and carbazole as raw materials, in an organic solvent, under the action of alkali, copper catalyst (cuprous iodide) and 1,10-phenanthroline ligand, 2-methoxy-3-X-phenyl halide and carbazole undergo a coupling reaction. During the reaction, 1,10-phenanthroline coordinates with Cu(I) to form a stable complex, effectively preventing the disproportionation and deactivation of Cu(I). Under the action of alkali, the nitrogen-hydrogen bond of carbazole is broken to generate nitrogen anion, which then reacts with the Cu(I) activated 2-methoxy-3-X-phenyl halide through oxidative addition and coordination to form an organocopper(III) intermediate. This organocopper(III) intermediate undergoes reductive elimination to realize the construction of CN bond, releases N-(2-methoxy-3-X-phenyl)carbazole intermediate and regenerates the Cu(I) active species, completing the catalytic cycle; wherein X is selected from methyl, fluorine, chlorine or bromine.

[0009] S2. Using the intermediate as a raw material, the intermediate is subjected to an ether bond cleavage reaction with boron tribromide. During the reaction, boron tribromide, as a strong Lewis acid, forms a complex by coordinating its boron atom with the lone pair electrons of the methoxy ether oxygen, which polarizes and activates the ether bond. Subsequently, the bromide ion attacks the methyl carbon, resulting in bimolecular nucleophilic substitution and removal of the methoxy group. After the reaction is completed, water is added for quenching to obtain a passivating agent for passivating perovskite thin film layers.

[0010] Its synthetic route is as follows: .

[0011] Preferably, the molar ratio of 2-methoxy-3-X-phenyl halide to carbazole is 1.05~1.3:1; wherein, an appropriate excess of 2-methoxy-3-X-phenyl halide ensures that carbazole reacts fully, improves conversion and yield, and because its solubility is better than that of carbazole, it is easy to remove effectively in subsequent extraction or column chromatography purification processes, avoiding the adverse effects of excessive raw material residue on product purity.

[0012] Preferably, the molar ratio of the intermediate to boron tribromide is 1:0.5~1. Since boron tribromide has strong hygroscopicity in air, at least 0.5 times the molar amount of boron tribromide should be added to the reaction system to ensure that the demethylation reaction proceeds fully. However, the amount of boron tribromide should not be too much, because it will release a lot of heat during the post-treatment quenching process. An excessively high proportion will significantly increase the danger of the quenching operation. Therefore, it is advisable to control it within 1 molar amount.

[0013] Preferably, the coupling reaction conditions are: stirring at 120℃~160℃ for 8h~18h.

[0014] Preferably, the substitution reaction conditions are: stirring at 15℃~20℃ for 2h~2.5h.

[0015] The third objective of this invention is to provide a perovskite solar cell, wherein the perovskite solar cell is composed of a conductive substrate, a hole transport layer, a perovskite light absorption layer, a passivation layer, an electron transport layer, a buffer layer, and a metal electrode stacked sequentially from bottom to top; wherein the passivation layer is made using the passivating agent of the above-mentioned passivation perovskite thin film layer.

[0016] Preferably, the thickness of the passivation layer is 15nm to 20nm, which is the conventional thickness of the passivation layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a novel passivating agent for perovskite thin films with a carbazole-phenol backbone, the general structural formula of which is: The passivating agent of the present invention for the perovskite thin film layer is a highly efficient passivating agent for perovskite thin films, which can accurately passivate defects in perovskite thin films, optimize the interface energy level arrangement, improve carrier transport efficiency, and significantly enhance the thermal and humidity stability of perovskite solar cell devices.

[0018] Unlike conventional para-substituted or long-chain linked carbazole derivatives, this invention employs a passivation structure synergistically combining a single-sided substitution (halogen atom or methyl group) and a single phenolic hydroxyl group. By controlling molecular stacking behavior through steric hindrance and combining the electronic properties of different substituents, multi-dimensional defect passivation is achieved, thereby significantly suppressing non-radiative recombination of charge carriers and extending carrier lifetime. This provides a new technical path for defect passivation in perovskite solar cells. Specifically, the phenolic hydroxyl group targets and anchors uncoordinated Pb on the perovskite surface through strong coordination. 2+ Defects, achieving Pb 2+ Precise passivation of single-site defects; when X is a halogen atom (F, Cl, Br), the unilateral halogen substituents assist in filling halide ion vacancies by virtue of their electronegativity and steric hindrance effect, and work together with the phenolic hydroxyl group to achieve synergistic passivation of both anion and cation defects; when X is CH3, the methyl substituents mainly suppress the π-π stacking and molecular aggregation of the carbazole ring through steric hindrance effect, thus optimizing the interfacial stacking morphology.

[0019] Furthermore, the molecular energy levels of the passivating agent in the passivated perovskite thin film layer of the present invention are highly matched with those of the perovskite active layer, which can significantly reduce the interfacial charge transport barrier, thereby effectively improving the open-circuit voltage, short-circuit current density and fill factor of the device, and obtaining better device output performance.

[0020] 2. This invention also provides a method for preparing a passivating agent for perovskite thin films. Using 2-methoxy-3-X-phenyl halide and carbazole as raw materials, in the presence of an organic solvent and under the action of a base, catalyst, and ligand, the 2-methoxy-3-X-phenyl halide and carbazole undergo a coupling reaction to obtain an intermediate. Using the intermediate as a raw material, the intermediate undergoes a substitution reaction with boron tribromide to obtain the passivating agent for perovskite thin films. The preparation method of this invention is simple, low-cost, and operates under mild reaction conditions. It also yields a high intermediate yield and has a low risk of halogen residue, making it easy to scale up for production. Compared to existing carbazole-based passivating agents, which require multiple protection / deprotection reactions, resulting in complex processes, higher costs, excessive halogen residue in some derivatives, and poor film-forming properties, the preparation method of this invention significantly reduces the difficulty and cost of preparation, making it more suitable for industrial applications.

[0021] By replacing the halogen substituents or fine-tuning the substituent groups on the carbazole ring, a series of stable derivatives with excellent passivation effects can be obtained. These derivatives can be flexibly selected based on cost control, environmental requirements, and device performance needs, balancing high efficiency, economy, and environmental friendliness. These compounds are suitable for various conventional perovskite solar cell device systems, with a wide range of applications. They fill the technological gap in existing carbazole-based single-sided halogen-substituted passivators and contribute to the industrialization of perovskite solar cells.

[0022] 3. Using the passivating agent of the perovskite thin film layer of the present invention as the passivation material, it is applied to the fabrication of a perovskite solar cell. The structure of the perovskite solar cell, from bottom to top, consists of: a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, a buffer layer, and a metal electrode. The passivation layer is formed by dissolving the passivating agent of the perovskite thin film layer in isopropanol followed by spin coating and annealing; or the passivating agent of the perovskite thin film layer is doped as an additive into the perovskite precursor solution, and bulk passivation of the perovskite thin film is achieved by blending and spin coating.

[0023] The passivation material interacts with uncoordinated Pb on the perovskite surface via phenolic hydroxyl groups. 2+ The strong coordination effect of the halogen and the auxiliary filling of halide ion vacancies by the unilateral halogen substituents achieve precise passivation of the dual defects of anions and cations, significantly suppressing nonradiative recombination of charge carriers and extending the carrier lifetime. At the same time, its molecular energy level is highly matched with the perovskite active layer, which can effectively reduce the interfacial charge transport barrier, optimize the interfacial energy level arrangement, and thus improve the open-circuit voltage, short-circuit current density and fill factor of the device. Attached Figure Description

[0024] Figure 1 The current-voltage curves are for the perovskite thin film layers with passivating agents applied in Examples 1 to 4 and for perovskite solar cells without passivating layers. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods.

[0027] In existing technologies, perovskite thin film passivators mainly include ammonium salts, pyridine and imidazole derivatives, phenolic small molecules, and carbazole derivatives, but all have significant shortcomings. Ammonium salt passivators easily introduce ionic impurities and have poor hydrophobicity, making them unable to effectively block water and oxygen corrosion; pyridine and imidazole derivatives have insufficient conjugation and weak charge carrier transport capabilities, and are mostly single-function passivators; phenolic small molecules have poor hydrophobicity and insufficient thermal stability, making them prone to desorption from the perovskite surface; carbazole derivatives are mostly para-substituted structures, which have problems such as easy molecular aggregation, poor interfacial compatibility, and limited passivation sites.

[0028] To address the problems existing in the prior art, the present invention provides a passivating agent for passivating perovskite thin films, the general structural formula of which is: Wherein, X is selected from halogen atoms or CH3. This invention is a novel organic passivating agent with a "carbazole-phenol" main structure. It solves the technical bottlenecks of high defect density, poor interfacial contact, and weak environmental stability of perovskite thin films by precisely passivating defects with a single phenolic hydroxyl group, optimizing carrier transport and hydrophobic properties with a carbazole conjugated skeleton, and providing steric hindrance and auxiliary passivation with a single-sided halogen substituent.

[0029] In addressing the problems of existing technologies, such as the easy introduction of ionic impurities and poor hydrophobicity of ammonium salt passivators, which cannot effectively block water and oxygen erosion, and the poor hydrophobicity, insufficient thermal stability, and easy desorption from perovskite surfaces of phenolic small molecules, this invention constructs a carbazole-phenol main structure. By utilizing the hydrophobicity and rigid planar structure of the carbazole conjugated skeleton, a dense and stable hydrophobic barrier is formed on the perovskite surface, effectively blocking water and oxygen erosion. At the same time, by leveraging the excellent thermal stability of the carbazole skeleton and the intermolecular π-π stacking effect, the bonding force between the passivation layer and the perovskite surface is significantly enhanced, avoiding molecular thermal desorption, thereby synergistically improving the long-term thermal and wet stability of the device.

[0030] To address the problems of insufficient conjugation, weak carrier transport capacity, and mostly single-function passivation of pyridine and imidazole derivatives in existing technologies, as well as the easy aggregation, poor interfacial compatibility, and single passivation site of carbazole derivatives, this invention achieves synergistic optimization of multiple functions by constructing a carbazole-phenol master structure and introducing a single-sided substituent (halogen atom or methyl group): On the one hand, the carbazole conjugated skeleton is used to enhance molecular conjugation and hydrophobicity, constructing an efficient carrier transport channel; on the other hand, the uncoordinated Pb is targeted and coordinated by a single phenolic hydroxyl group. 2+ Halogen atoms assist in filling halide ion vacancies, achieving synergistic passivation of both cation and anion defects and interfacial energy level regulation, breaking through the limitations of traditional single-function passivation. On the other hand, by leveraging the steric hindrance effect of unilateral halogen substituents or methyl groups, molecular aggregation is effectively suppressed and interfacial stacking is optimized, significantly improving interfacial compatibility. Thus, the problems of weak carrier transport, single passivation site, and molecular aggregation are solved simultaneously.

[0031] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will provide a detailed description in conjunction with specific embodiments: Example 1 A method for preparing a passivating agent for passivating perovskite thin films includes the following steps: Synthesis of S1 and Intermediate 1: Carbazole (13 g, 77.75 mmol), 1-bromo-2-methoxy-3-methylbenzene (20.32 g, 101.1 mmol), potassium carbonate (21.49 g, 155.49 mmol), cuprous iodide (0.74 g, 3.89 mmol), 1,10-phenanthroline (1.40 g, 7.77 mmol), and 156 mL of NMP were added to a reaction flask. After purging with nitrogen, the mixture was heated to 160 °C and reacted for 18 h. After the reaction was completed, the insoluble copper salt was filtered through a diatomaceous earth funnel. The filtrate was collected and successively washed with NMP by hot water at 60 °C, extracted with ethyl acetate, and the organic phase was washed multiple times with water. The mixture was separated, dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The reaction product was then separated by column chromatography to obtain Intermediate 1 with a yield of 58.5% (13.07 g). The synthetic route is as follows: .

[0032] Synthesis of S2 and Compound 1: Intermediate 1 (12 g, 41.76 mmol) and 120 mL of dichloromethane were added to a reaction flask. The mixture was magnetically stirred, and the temperature was maintained at 15 °C. Boron tribromide (8.37 g, 33.41 mmol) was added dropwise. After the addition was complete, a TLC reaction was carried out at 20 °C for 2 h. After the TLC reaction was completed, 200 mL of dichloromethane was added to the reaction flask, and the reaction solution was poured into 600 mL of water under stirring. The mixture was stirred thoroughly, and the aqueous phase was discarded. The solvent was concentrated under reduced pressure, and the reaction was then separated by column chromatography to obtain the passivating agent for perovskite thin films. Its structural formula is [insert structural formula here]. The yield was 67.1% (7.66 g), and the synthetic route was as follows: .

[0033] Example 2 A method for preparing a passivating agent for passivating perovskite thin films includes the following steps: Synthesis of S1 and Intermediate 2: Carbazole (14 g, 83.73 mmol), 2-bromo-6-fluoroanisole (20.60 g, 100.47 mmol), potassium carbonate (23.14 g, 167.45 mmol), cuprous iodide (0.80 g, 4.19 mmol), 1,10-phenanthroline (1.51 g, 8.37 mmol), and 168 mL of DMF were added to a reaction flask. After purging with nitrogen, the mixture was heated to 120 °C and reacted for 10 h. After the reaction was completed, the insoluble copper salt was filtered through a diatomaceous earth funnel. The filtrate was collected and successively washed with water, DMF, and extracted with ethyl acetate. The organic phase was washed multiple times with water and separated. The product was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the reaction product was separated by column chromatography to obtain Intermediate 2 with a yield of 64.3% (15.68 g). The synthetic route is as follows: .

[0034] Synthesis of S2 and Compound 2: Intermediate 2 (12 g, 41.19 mmol) and 120 mL of dichloromethane were added to a reaction flask. The mixture was magnetically stirred, and the temperature was controlled at 15 °C. Boron tribromide (8.26 g, 32.95 mmol) was added dropwise. After the addition was complete, a TLC reaction was carried out at 20 °C for 2 h. After the TLC reaction was completed, 200 mL of dichloromethane was added to the reaction flask, and the reaction solution was poured into 600 mL of water under stirring. The mixture was stirred thoroughly, and the aqueous phase was discarded. The solvent was concentrated under reduced pressure, and the reaction was then separated by column chromatography to obtain the passivating agent for perovskite thin films. Its structural formula is as follows: The yield was 78.4% (8.96 g), and the synthetic route was as follows: .

[0035] Example 3 A method for preparing a passivating agent for passivating perovskite thin films includes the following steps: Synthesis of S1 and Intermediate 3: Carbazole (10 g, 59.8 mmol), 1-bromo-3-chloro-2-methoxybenzene (15.89 g, 71.77 mmol), potassium carbonate (16.53 g, 119.61 mmol), cuprous iodide (0.57 g, 2.99 mmol), 1,10-phenanthroline (1.08 g, 5.98 mmol), and 120 mL of DMF were added to a reaction flask. After purging with nitrogen, the mixture was heated to 120 °C and reacted for 18 h. After the reaction was completed, the insoluble copper salt was filtered through a diatomaceous earth funnel, the filtrate was collected, DMF was washed with water, and the mixture was extracted with ethyl acetate. The organic phase was washed several times with water and separated. The solution was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the reaction product was separated by column chromatography to obtain Intermediate 3 with a yield of 82.2% (15.13 g). The synthetic route is as follows: .

[0036] Synthesis of S2 and Compound 3: Intermediate 3 (11 g, 35.74 mmol) and 110 mL of dichloromethane were added to a reaction flask. The mixture was magnetically stirred and cooled to 15 °C. Boron tribromide (7.16 g, 28.59 mmol) was added dropwise at this temperature. After the addition was complete, a TLC reaction was carried out at 20 °C for 2 h. After the TLC reaction, 200 mL of dichloromethane was added to the reaction flask, and the reaction solution was poured into 500 mL of water under stirring. The mixture was stirred thoroughly, and the aqueous phase was discarded. The solvent was concentrated under reduced pressure, and the reaction was then separated by column chromatography to obtain the passivating agent for perovskite thin films. Its structural formula is [insert structural formula here]. The yield was 79.6% (8.36 g), and the synthetic route was as follows: .

[0037] Example 4 A method for preparing a passivating agent for passivating perovskite thin films includes the following steps: Synthesis of S1 and Intermediate 4: Carbazole (10 g, 59.80 mmol), 1-bromo-3-iodo-2-methoxybenzene (19.65 g, 62.79 mmol), potassium carbonate (16.53 g, 119.61 mmol), cuprous iodide (1.14 g, 11.96 mmol), 1,10-phenanthroline (2.16 g, 11.96 mmol), and 120 mL of DMF were added to a reaction flask. The atmosphere was purged with nitrogen, and the mixture was heated to 120 °C for 8 h. After the reaction was completed, the insoluble copper salt was filtered through a diatomaceous earth funnel. The filtrate was collected, washed successively with water and DMF, extracted with ethyl acetate, and the organic phase was washed repeatedly with water. The mixture was then separated, dried over anhydrous sodium sulfate, and the solvent was concentrated under reduced pressure. The reaction product was then separated by column chromatography to obtain Intermediate 4, with a yield of 56.8% (11.96 g). The synthetic route is as follows: .

[0038] Synthesis of S2 and Compound 4: Intermediate 4 (11 g, 31.23 mmol) and 110 mL of dichloromethane were added to a reaction flask. The mixture was magnetically stirred and cooled to 15 °C. Boron tribromide (6.26 g, 24.98 mmol) was added dropwise at this temperature. After the addition was complete, the reaction was carried out at 20 °C for 2 h. The reaction was then stopped by TLC. 200 mL of dichloromethane was added directly, followed by slow pouring of the reaction solution into 600 mL of water under stirring. After thorough stirring, the aqueous phase was discarded, and the solvent was concentrated under reduced pressure. The reaction product was then separated by column chromatography to obtain the passivating agent for perovskite thin films. Its structural formula is [insert structural formula here]. The yield was 72.8% (7.69 g), and the synthetic route was as follows: .

[0039] application: Perovskite solar cells were fabricated using azole-phenol compounds obtained in Examples 1-4 as passivation materials. The structure of the perovskite solar cell, from bottom to top, consists of: FTO, hole transport layer, perovskite layer, passivation layer, electron transport layer, buffer layer, and metal electrode, and includes the following steps:

[0040] FTO pretreatment: A 2.2 mm thick FTO substrate was ultrasonically cleaned sequentially with deionized water, ethanol, and acetone for 15 min each. It was then dried in a forced-air drying oven at 100°C for 15 min to obtain a dried FTO substrate. The dried FTO substrate was then placed in a UV ozone generator and treated at 30W for 25 min. Through the dual effects of UV degradation and ozone oxidation, residual organic matter on the surface was further removed, while simultaneously increasing the hydrophilicity and surface energy of the FTO substrate. After treatment, the substrate was quickly transferred to a nitrogen glove box to obtain a pretreated substrate for later use.

[0041] Preparation of the hole transport layer: [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl] (Me-4PACz, purity ≥99%) powder was mixed with ultra-dry ethanol in a certain proportion and stirred at room temperature for 30 min to obtain a hole transport solution (Me-4PACz solution) with a concentration of 1 mmol / L. 40 μL of filtered Me-4PACz solution was uniformly dropped onto the surface of the pretreated substrate. The spin coating parameters were set as follows: spin speed 4000 rpm, spin coating time 30 s, and acceleration 2000 rpm / s. The spin coating program was started to allow the Me-4PACz solution to spread uniformly and form a thin film. After spin coating, the pretreated substrate was immediately transferred to a hot stage in a glove box and annealed at 100 °C for 10 min in a nitrogen atmosphere to form a hole transport layer on the pretreated substrate, resulting in a substrate with a Me-4PACz hole transport layer. The thickness of the hole transport layer was 30 nm.

[0042] Preparation of the perovskite light-absorbing layer: PbI₂ (lead iodide, purity 99.99%), MABr (methylamine bromide, purity 99.5%), PbBr₂ (purity 99.99%), FAI (formamidinium iodide, purity 99.5%), and CsI (cesium iodide, purity 99.99%) were dissolved in a mixed solvent of DMF:DMSO (DMF:DMSO = 4:1) and magnetically stirred at room temperature for 4 hours to form a perovskite light-absorbing layer with the chemical formula CsI. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95A perovskite precursor solution of 3 was prepared. The substrate with the Me-4PACz hole transport layer was fixed on a spin coater, and 50 μL of the perovskite precursor solution was added. A two-stage spin coating program was used: the first stage was 500 rpm for 5 seconds; the second stage was 4000 rpm for 30 seconds. At 15 seconds into the second stage of spin coating, 100 μL of chlorobenzene antisolvent was rapidly added using a pipette. After spin coating, the substrate with the Me-4PACz hole transport layer was immediately transferred to a hot stage inside a glove box and annealed at 120°C for 30 minutes under a nitrogen atmosphere to form a perovskite layer on the hole transport layer, resulting in a substrate with a perovskite layer thickness of 650 nm.

[0043] Preparation of the passivation layer: The azole-phenol compound powder was mixed with isopropanol in a certain proportion and stirred at room temperature for 30 min to obtain a passivation solution with a concentration of 1 mmol / L. 30 μL of the filtered passivation solution was uniformly dropped onto the surface of the perovskite layer. The spin coating parameters were set as follows: spin speed 5000 rpm, spin coating time 20 s, and acceleration 2000 rpm / s. The spin coating program was started to make the passivation solution spread evenly and form a thin film. After spin coating, the substrate with the perovskite layer was immediately transferred to the hot stage in the glove box and annealed at 100 °C for 5 min under a nitrogen atmosphere to form a passivation layer on the perovskite layer, resulting in a substrate with a passivation layer thickness of 20 nm.

[0044] Fabrication of electron transport layer and buffer layer: The substrate with passivation layer was transferred to a thermal evaporation coating apparatus, the chamber was closed and the vacuum pump was started, and the chamber vacuum was evacuated to below 5 × 10⁻⁶. -4 Pa. With C 60 The powder was used as the evaporation source, and the evaporation rate was controlled at 0.1 nm / s. When C... 60 When the layer thickness reaches 30 nm, evaporation is stopped; then the BCP evaporation source is switched to, the evaporation rate is controlled at 0.05 nm / s, and the deposition thickness is 5 nm.

[0045] Fabrication of metal electrodes: A layer of silver (Ag) with a thickness of 100 nm is deposited on the electron transport layer to obtain a perovskite solar cell.

[0046] To compare with this invention and verify the effect of carbazole-phenol passivating agents on improving the photoelectric conversion efficiency and stability of perovskite solar cells, this invention also provides a method for preparing perovskite solar cells, namely, without designing a passivation layer when preparing perovskite solar cells.

[0047] The performance of the above perovskite solar cells was tested, and the results are shown in Table 1.

[0048] Table 1 shows the performance data of the azole-phenol compounds used in Examples 1-4 and the perovskite solar cells without passivation layers. No passivation layer 1.14 23.37 78.28 20.94 Example 1 1.15 23.97 77.69 21.48 Example 2 1.15 23.78 79.27 21.64 Example 3 1.15 23.43 81.29 21.82 Example 4 1.14 23.92 79.28 21.65 Combining Table 1 and Figure 1 It was found that, through specific molecular structure design, the passivating agent of the passivated perovskite thin film layer of this invention, when used as a passivation material, can significantly improve the photoelectric conversion efficiency of perovskite solar cells. Its core advantage stems from the synergistic passivation effect of the unilateral halogen substituent and the carbazole-phenol backbone: the phenolic hydroxyl group precisely anchors the uncoordinated Pb on the perovskite surface through strong coordination. 2+ The carbazole conjugated skeleton provides an excellent hydrophobic barrier and carrier transport channel, while the single-sided halogen substituents (F, Cl, Br) inhibit molecular aggregation and optimize interface stacking through steric hindrance. At the same time, the electronegativity of halogen atoms and vacancy defects are used to form auxiliary coordination, achieving precise passivation of both cation and anion defects.

[0049] Among the halogen substituents, the chlorinated derivative (Example 3) exhibited the best overall performance (PCE of 21.82% and fill factor of 81.29%), which is attributed to the moderate atomic radius and electronegativity of the chlorine atom—providing both adequate steric hindrance to optimize molecular orientation and interfacial contact, and sufficient coordination ability to assist in passivating halogen vacancies, while avoiding the interfacial dipole mismatch problem that may be caused by the excessive electronegativity of the fluorine atom; the brominated derivative (Example 4), due to its larger atomic radius and enhanced steric hindrance, although its passivation effect was slightly inferior to that of the chlorinated derivative, was still significantly better than the device without a passivation layer; the fluorinated derivative (Example 2), although having the strongest electronegativity, had a smaller atomic size that resulted in insufficient steric hindrance effect, easy molecular aggregation, and relatively weak interfacial adaptability, with performance between that of the chlorinated and brominated derivatives.

[0050] From an industrialization perspective, chlorinated derivatives offer both performance advantages and economical synthesis: starting from 1-bromo-3-chloro-2-methoxybenzene, they can be efficiently prepared in two steps via Ullmann coupling and demethylation, with low raw material costs (the market price of chlorinated aromatics is significantly lower than that of bromo / iodinated derivatives), mild reaction conditions (120°C), and an intermediate yield as high as 82.2%, while avoiding the halogen residue risk that may exist in bromo / iodinated derivatives. In contrast, although bromo derivatives have inferior performance, they require expensive iodinated raw materials (1-bromo-3-iodo-2-methoxybenzene), resulting in higher synthesis costs and lower yields (56.8%). Fluorinated raw materials (2-bromo-6-fluoroanisole) are moderately priced, but their performance is inferior to that of chlorinated derivatives. Methyl-substituted derivatives (Example 1) are simple to synthesize, but lack halogen-assisted passivation sites, have a low filling factor (77.69%), and have the worst overall performance.

[0051] In summary, the passivating agent for chlorinated perovskite thin films of the present invention achieves the best balance between passivation effect, synthesis efficiency, cost control and environmental friendliness, and has the greatest potential for large-scale application.

[0052] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A passivating agent for perovskite thin film layers, characterized in that, The general structural formula of the passivating agent for the passivating perovskite thin film layer is: , where X is selected from halogen atoms or -CH3.

2. The passivating agent for passivating perovskite thin films according to claim 1, characterized in that, X is selected from F, Cl, Br or -CH3.

3. The passivating agent for passivating perovskite thin films according to claim 1, characterized in that, The passivating agent for the passivated perovskite thin film layer is selected from... , , or .

4. A method for preparing a passivating agent for a perovskite thin film layer as described in claim 1, characterized in that, Includes the following steps: Using 2-methoxy-3-X-phenyl halide and carbazole as raw materials, in the presence of an organic solvent and under the action of a base, catalyst and ligand, 2-methoxy-3-X-phenyl halide and carbazole undergo a coupling reaction to obtain an intermediate; wherein X is selected from methyl, fluorine, chlorine or bromine. Using an intermediate as a raw material, the intermediate is subjected to a substitution reaction with boron tribromide to obtain a passivating agent for passivating perovskite thin films.

5. The preparation method according to claim 4, characterized in that, The molar ratio of 2-methoxy-3-X-phenyl halide to carbazole is 1.05~1.3:

1.

6. The preparation method according to claim 4, characterized in that, The molar ratio of the intermediate to boron tribromide is 1:0.5~1.

7. The preparation method according to claim 4, characterized in that, The conditions for the coupling reaction are: stirring at 120℃~160℃ for 8h~18h.

8. The preparation method according to claim 4, characterized in that, The conditions for the substitution reaction are: stirring at 15℃~20℃ for 2h~2.5h.

9. A perovskite solar cell, characterized in that, The perovskite solar cell is composed of a conductive substrate, a hole transport layer, a perovskite light absorption layer, a passivation layer, an electron transport layer, a buffer layer, and a metal electrode stacked sequentially from bottom to top. The passivation layer is prepared using the passivating agent for the perovskite thin film layer as described in claim 1.

10. The perovskite solar cell according to claim 9, characterized in that, The thickness of the passivation layer is 15nm~20nm.

Images