Phosphonic acid-anchored hexa-perylenophthalocyanine self-assembled monolayer and preparation method and application thereof

Abstract

This invention relates to the field of perovskite solar cell technology, specifically to a phosphate-anchored hexabenzo[a]methyl ether self-assembled monomolecule material, its preparation method, and its applications. The self-assembled monomolecule material uses hexabenzo[a]methyl ether as its core framework, wherein x groups are -(L)m-PO3H2, y groups are -H or functional substituents, x+y=6, where x is an integer from 1 to 6, and y is an integer from 0 to 5; L represents a linking group selected from C1 to C2. 12 The material comprises one or more of the following: straight-chain or branched alkylene groups, C2-C8 alkenyl groups, C2-C8 ynylene groups, phenylene groups, and biphenylene groups; m represents the length of the linking group, which is an integer from 0 to 6. When m=0, it indicates that the phosphate group is directly linked to the hexabenzo[a]oxon]core backbone. This invention develops a novel self-assembled single-molecule material that combines a super-large π-conjugated rigid backbone, multi-toothed anchoring function, super-strong intermolecular π-π interaction, and interface passivation function. This material has significant scientific and industrial value for realizing efficient and stable perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and more particularly to a phosphate-anchored hexabenzoclavyl self-assembled monomolecule material, its preparation method, and its application. Background Technology

[0002] In recent years, phosphate-based self-assembled monolayer materials have gradually replaced traditional hole transport materials as the preferred hole-selective layer material for inverted perovskite solar cells due to their molecular-level precision, ultrathin film formation capability, and excellent energy level matching characteristics. These materials use phosphate groups as anchoring groups and achieve self-assembly by forming chemical bonds with transparent conductive oxide substrates such as ITO or FTO. Simultaneously, they utilize the hole transport characteristics of the conjugated framework to achieve efficient charge extraction. The advantages of self-assembled monolayer materials are mainly reflected in: (1) simple synthesis and extremely low dosage, which helps reduce costs; (2) chemical bonding with the substrate, resulting in high stability; (3) thin films can be prepared by methods such as immersion, which facilitates high-throughput, low-cost manufacturing; and (4) ultrathin film thickness helps reduce series resistance and improve battery efficiency.

[0003] However, existing self-assembled monolayer materials such as carbazole and triphenylamine still have the following technical drawbacks:

[0004] First, the weak intermolecular π-π interactions result in insufficient molecular packing during self-assembly, leading to inadequate film uniformity and coverage. The uncontrolled self-assembly state and uneven molecular-scale distribution of self-assembled monolayers on the substrate result in poor surface wettability to perovskite precursor solutions, easily leading to numerous micropores and suboptimal crystallization at the buried interface. Studies have shown that self-assembled monolayers tend to aggregate on the substrate and may be desorbed by strongly polar solvents, causing a decline in perovskite film quality.

[0005] Second, the conjugation extension of rigid frameworks is limited, and charge transport capabilities need further improvement. Existing materials have relatively simple conjugated frameworks and low carrier mobility, making it difficult to meet the requirements of high-efficiency devices for hole extraction and transport capabilities.

[0006] Third, the passivation capability at the interface with the perovskite layer is insufficient. Existing self-assembled monolayer materials lack sufficient chemical coordination sites at the interface with the perovskite layer, making it difficult to adequately passivate the uncoordinated Pb at the perovskite subsurface interface. 2+ The defects lead to severe nonradiative recombination losses at the interface, limiting further improvements in the device's open-circuit voltage and fill factor.

[0007] Fourth, insufficient long-term operational stability. Phosphate-based self-assembled monolayers are mainly anchored to the ITO surface via hydrogen bonds, and are prone to dissociation under photothermal synergy, leading to molecular desorption and migration into the perovskite layer, causing perovskite degradation and device performance decline. Under full-spectrum illumination at 85℃, the I3 content in perovskite films containing conventional phosphate-based self-assembled monolayers... - The concentration is 73 times higher than that of films without self-assembled monolayers. Traditional monophosphate anchoring groups are prone to desorption from the substrate surface during long-term operation, and the lack of sufficiently strong π-π stacking reinforcement between molecules leads to the decay of interfacial adhesion over time, thus limiting device lifetime.

[0008] To address the aforementioned issues, researchers have attempted improvements through methods such as introducing methoxy electron-donating groups, extending alkyl chains, and employing co-adsorption strategies. For instance, self-assembled monolayers with phosphonic acid groups, through conjugation extension and anchoring strategies, possess unique spatially twisted structures that endow the self-assembled monolayers with excellent film-forming properties and surface wettability. The extended conjugation range and ordered molecular arrangement enhance interfacial charge extraction and transport capabilities. However, these improvements have not fundamentally solved the problems of insufficient rigidity of the conjugated framework, inadequate intermolecular π-π packing, and low intrinsic hole mobility in existing self-assembled monolayer materials.

[0009] Hexabenzo[a]methyl ether is a polycyclic aromatic hydrocarbon molecule composed of 42 carbon atoms with high symmetry (D6h symmetry group). With a diameter of approximately 1.4 nm, it is a typical graphene fragment, consisting entirely of sp²-hybridized six-membered carbon rings and is a planar molecule. Hexabenzo[a]methyl ether possesses an ultra-large π-conjugated plane, extremely high carrier mobility, and excellent self-assembly properties. It can self-assemble into long-range ordered columnar structures in solution or solid phase, exhibiting very high charge mobility. Simultaneously, the strong π-π interactions between hexabenzo[a]methyl ether molecules can form close-packed structures, which is beneficial for forming highly ordered self-assembled monolayers, but also leads to extremely low solubility in common solvents, significantly limiting its application in solution-based material preparation. To date, there are no reports of using hexabenzo[a]methyl ether as a large π-conjugated rigid core to construct phosphate-based self-assembled monolayers for use in perovskite solar cell hole transport layers. Notably, hexabenzo[a]methyl ether not only possesses an ultra-large π-conjugated plane but also exhibits unique physical properties in its electronic behavior. For example, the intrinsic hole mobility of columnar self-assemblies of hexabenzo[a]coronavirus can reach 10. -3 cm 2 ·V -1 ·s -1 The magnitude (existing reports indicate that hexabenzo[a]cor derivatives can achieve hole mobility of 0.4–1.5 × 10⁻⁶ in columnar phases) is significant. -3 cm 2 ·V -1 ·s -1It exhibits an extremely narrow localized Gaussian distribution (depth of only about 10±3 meV). How to integrate these outstanding physical properties of hexabenzo[a]cor with phosphate-based self-assembly technology is a technological gap that has never been touched in this field of research.

[0010] Therefore, developing a novel self-assembled single-molecule material that combines an ultra-large π-conjugated rigid framework, ultra-strong intermolecular π-π interactions, and interface passivation functions is of great scientific significance and industrial value for realizing efficient and stable perovskite solar cells. Summary of the Invention

[0011] In view of this, the purpose of this invention is to propose a phosphate-anchored hexabenzokeratyl self-assembled monolayer material, its preparation method, and its applications, to solve the problems of weak π-π interactions, low intrinsic hole mobility, and poor long-term stability in existing self-assembled monolayer materials. This invention can achieve multi-site interface passivation, and simultaneously, it innovatively endows the hole transport layer with room-temperature non-dispersive hole transport properties.

[0012] To achieve the above objectives, this invention provides a phosphate-anchored hexabenzo[a]colony-based self-assembled monomolecule material, wherein the self-assembled monomolecule material uses hexabenzo[a]colony as its core framework and has the following structural formula:

[0013]

[0014] Among them, R1-R6 have x groups that are -(L)m-PO3H2 and y groups that are -H or functional substituents, x+y=6, where x is an integer from 1 to 6 and y is an integer from 0 to 5;

[0015] L represents the linking group, selected from one or more of the following: straight-chain alkyl or branched alkylene, alkenyl, ynylene, phenylene, and biphenylene; m represents the length of the linking group, which is an integer from 0 to 12. When m=0, it means that the phosphate group is directly linked to the hexabenzo[a]core skeleton.

[0016] The functional substituent is selected from at least one of the following groups: C1~C 18 Straight-chain or branched alkyl groups, C1~C 18 alkoxy groups, C1~C 18 alkylthio groups, C1~C 18 Alkylamino, halogen (F, Cl, Br, I) groups, cyano, hydroxyl, trifluoromethyl, nitro, and oxygen- or sulfur-containing heteroatomic groups containing lone pairs of electrons.

[0017] The chemical structure of the hexabenzo[a]core is a disk-shaped planar large π-conjugated structure consisting of seven fused benzene rings, including a central benzene ring and six peripheral benzene rings, forming a perfect hexagonal planar structure with D6h symmetry.

[0018] Preferably, the L linker group is selected from C1~C1. 12 One or more of the following: straight-chain or branched alkylene, C2-C8 alkenyl, C2-C8 ynylene, phenylene, and biphenylene.

[0019] Preferably, the functional substituent is selected from C6~C6. 12 Alkyl groups, C6~C 12 The alkyl chain consists of one of the following: an alkoxy group, a fluorine atom, a methoxy group (—OCH3), or a methylthio group (—SCH3). The introduction of the alkyl chain can improve the solubility of hexabenzo[a]corona] in conventional organic solvents, solving the problem of its intrinsically low solubility. Simultaneously, the steric hindrance effect of the alkyl chain can regulate the self-assembly orientation of the molecule on the substrate. The oxygen or sulfur atom in the methoxy and methylthio groups contains lone pairs of electrons, which can interact with uncoordinated Pb atoms in perovskites. 2+ Forming coordinate bonds effectively passivates interface defects.

[0020] More preferably, the functional substituent is a fluorine atom. Fluorine atoms have strong electronegativity, and their introduction can reduce the HOMO / LUMO energy levels of the hexabenzo[a]core, adjust the energy level matching, and at the same time, the hydrophobic properties of fluorine atoms can enhance the hydrophobicity of the self-assembled monolayer, inhibit the erosion of the perovskite layer by water, and improve the stability of the device.

[0021] Preferably, the L linking group is selected from C2-C6 alkylene groups (such as ethylene, propyleneene, butylene) or phenylene groups.

[0022] In some preferred embodiments of the present invention, when x = 2, 3, 4, 5, or 6, the material is a polyphosphonic acid-type self-assembled monolayer material. The multidentate phosphate anchoring group forms multiple covalent bonding sites with the substrate surface through multiple phosphate groups, significantly enhancing the binding strength with the substrate and effectively suppressing the desorption problem of the phosphate-based self-assembled monolayer under photothermal stress. The hexabenzo[a]corona] core framework is connected to 2 to 6 phosphate groups through edge benzene ring positions, forming a hexabenzo[a]corona-polyphosphonic acid structure. The unique disk-shaped large π-conjugated planar structure of hexabenzo[a]corona can simultaneously accommodate the connection of multiple phosphate anchoring groups, forming a multidentate anchoring effect.

[0023] In some preferred embodiments of the present invention, the hexabenzo[a]cobalamin large π-conjugated molecule functionalized phosphate-based self-assembled monomolecule material has one or more of the following representative structures (HBC is the hexabenzo[a]cobalamin core framework):

[0024] Representative Structure 1: Monophosphonic acid-type hexabenzo[a]kJ self-assembled single-molecule material

[0025] Structural formula: HBC-(L) m-PO3H2 (n=1, i.e., a phosphate anchoring group is attached to the hexabenzo[a]core).

[0026] Representative Structure 2: Bisphosphonic acid-type hexabenzo[a]kJ self-assembled single-molecule material

[0027] Structural formula: HBC-[((L) m -PO3H2]2 (n=2, that is, the hexabenzo[a]core is connected to two phosphate anchoring groups, and the two phosphate groups can be located at the relative edge positions of the hexabenzo[a]core).

[0028] Representative Structure 3: Triphosphonic acid-type hexabenzo[a]methyl ether self-assembled monomolecule material

[0029] Structural formula: HBC-[((L) m -PO3H2]3 (n=3, that is, the hexabenzo[a]core is connected to three phosphate anchoring groups, and the three phosphate groups can be located at alternating edge positions of the hexabenzo[a]core).

[0030] Representative Structure 4: Hexaphosphonic acid-type hexabenzo[a]kJ self-assembled single-molecule material

[0031] Structural formula: HBC-[((L) m -PO3H2]6 (n=6, meaning that all six peripheral benzene ring positions of the hexabenzo[a]core are connected to phosphate anchoring groups, forming a hexadentate fully anchored structure).

[0032] The structural formula is as follows:

[0033]

[0034] In some preferred embodiments of the present invention, when the phosphate group is connected to the hexabenzo[a]core via the linking group L, the introduction of the linking group L can effectively increase the spatial degree of freedom of the phosphate group, allowing it to extend more fully to the substrate surface and achieve effective chemical bonding.

[0035] The present invention also provides a method for preparing the phosphate-anchored hexabenzoclaw-based self-assembled monomolecule material, wherein the preparation method adopts method A or method B; considering the problem of the low intrinsic solubility of hexabenzoclaw, the present invention designs a synthetic strategy of introducing soluble groups stepwise and constructing the target molecule step by step.

[0036] Method A includes the following steps: synthesis of hexabenzo[a]core → functionalization of edge groups → introduction of linking groups → phosphonate esterification → deesterification and hydrolysis;

[0037] Method B includes the following steps: hexabenzocormide precursor method → ​​edge functionalization → cyclization reaction → phosphonate esterification → deesterification and hydrolysis.

[0038] The hexabenzo[a]core skeleton is synthesized by any of the following methods:

[0039] Method A:

[0040] (1) Diels-Alder cycloaddition method: using dibenzothrone as raw material, hexabenzothrone is obtained by reductive cyclization reaction with zinc / zinc chloride;

[0041] (2) Oxidative cyclization dehydrogenation method: Using polyphenyl-substituted benzene as a precursor, oxidative cyclization is carried out through the Scholl reaction catalyzed by FeCl3 or AlCl3 / CuCl2 oxidants to construct the hexabenzo[a]core skeleton;

[0042] (3) Precursor cyclization method: Using 2-bromobenzoyl chloride as raw material, hexabenzoyl chloride and its derivatives are synthesized through Friedel-Crafts acylation and borylation steps.

[0043] The edge functionalization is performed by dissolving the obtained hexabenzo[a]corona] core framework in a solvent and then performing edge functionalization using any of the following methods:

[0044] (a) Halogenation reaction: A halogen atom is introduced into the benzene ring position at the edge of the hexabenzo[a] ...

[0045] (b) Alkylation reaction: Introducing alkyl chains or alkyl chains containing functional groups at the edge benzene ring position of hexabenzo[a]col to improve the solubility of hexabenzo[a]col;

[0046] (c) Direct functionalization: hydroxyl and carboxyl active functional groups are introduced into the edge of hexabenzo[a] through electrophilic substitution reaction.

[0047] In method A, the linking group is introduced by coupling the obtained edge-functionalized hexabenzo[a]col] intermediate with a linking group precursor containing a reactive end to introduce a linking group L. The linking group precursor includes, but is not limited to, haloalkylphosphonates, haloarylphosphonates, alkenylphosphonates, alkynylphosphonates, etc.

[0048] When m≥1, the linking group L can be introduced in any of the following ways:

[0049] (a) Alkylation reaction: The marginally halogenated hexabenzo[a]col] is reacted with diethyl halogenated alkylphosphonate under alkaline conditions (such as K2CO3, Cs2CO3) to directly introduce alkyl linkage chains and phosphonate groups;

[0050] (b) Suzuki coupling reaction: The marginally halogenated hexabenzo[a]corona] is Suzuki coupled with the boronic acid ester-substituted aryl phosphonate (catalyzed by Pd(PPh3)4 or Pd(dppf)Cl2, with Na2CO3 or K3PO4 as the base and toluene / water or DMF as the solvent), introducing an aryl linker chain;

[0051] (c) Sonogashira coupling reaction: The marginally halogenated hexabenzo[a]corona] is coupled with an alkyne phosphonate via Sonogashira coupling (Pd(PPh3)2Cl2 / CuI catalysis, triethylamine or diisopropylamine as base, THF or DMF as solvent) to introduce an alkyne linker chain.

[0052] The phosphonate esterification method involves further reacting the resulting hexabenzo[a]col] intermediate, which is linked to a linking group and a phosphonate ester, under alkaline conditions to obtain the phosphonate ester intermediate HBC-(L). m -PO(OR)2, where HBC is the hexabenzo[a]core skeleton and R is a C1~C4 alkyl group, the reaction temperature is 60~120℃ and the reaction time is 6~24 hours; the degreasing and hydrolysis method is to hydrolyze the phosphonate intermediate obtained in step four under acidic or alkaline conditions to obtain the target phosphonic acid compound.

[0053] The deesterification reaction can be carried out in any of the following ways:

[0054] (a) Acid hydrolysis: Dissolve the phosphonate intermediate in a suitable solvent (such as dichloromethane or 1,4-dioxane), add hydrochloric acid or trimethylbromosilane (TMSBr), react at room temperature to reflux temperature for 4 to 12 hours, and then add water or alcohol solvent to precipitate the product;

[0055] (b) Alkaline hydrolysis: Dissolve the phosphonate intermediate in an alcohol solvent (such as ethanol), add an aqueous solution of sodium hydroxide or potassium hydroxide, heat under reflux for 6 to 24 hours, adjust the pH to acidic with hydrochloric acid after the reaction, and extract, concentrate and purify to obtain the target product.

[0056] More preferably, the trimethylbromosilane (TMSBr) method is used for deesterification. This method is mild, complete, and has few side reactions, and is particularly suitable for the acid / base sensitive hexabenzo[a]cosyl π-conjugated skeleton.

[0057] Optional optimized synthetic route – precursor cyclization followed by functionalization

[0058] Method B:

[0059] Step 1: Synthesis of hexabenzo[a]coronavirus precursor

[0060] Synthesize hexabenzo[a]cor precursors (such as polyphenyl-substituted benzenes, stilbene derivatives, etc.) using any of the following methods:

[0061] (1) Hexaphenylbenzene (HPB) method: Hexaphenylbenzene is synthesized from acetophenone through aldol condensation, Diels-Alder cycloaddition and other reactions;

[0062] (2) Suzuki coupling method: using 1,2,4,5-tetrabromobenzene and phenylboronic acid as raw materials, a Suzuki coupling reaction is carried out under palladium catalysis to obtain pentaphenylbenzene or hexaphenylbenzene derivatives;

[0063] (3) Stille coupling method: Tributylphenyltin is used to perform Stille cross coupling with halobenzene to construct a polyphenyl substituted benzene skeleton.

[0064] Step 2: Marginal Functionalization

[0065] The obtained hexabenzo[a]corona] precursor (such as hexaphenylbenzene) is dissolved in a solvent, and edge functionalization is performed by any of the following methods:

[0066] (a) Halogenation reaction: Halogen atoms (Br, I) are introduced into the benzene ring position at the edge of the precursor to obtain a halogenated precursor, which serves as the reaction site for subsequent coupling reactions;

[0067] (b) Alkylation reaction: Introducing alkyl chains or alkyl chains containing functional groups at the edge of the benzene ring of the precursor to improve the solubility of the intermediate;

[0068] (c) Direct functionalization: introducing active functional groups such as hydroxyl and carboxyl groups at the edge of the precursor through electrophilic substitution reaction.

[0069] Step 3: Cyclization reaction

[0070] The precursor with marginally functionalized groups was subjected to oxidative cyclization and dehydrogenation (Scholl reaction) to construct a hexabenzo[a]corona] core framework. The specific method is as follows:

[0071] The precursor was dissolved in dichloromethane, nitromethane or dichloroethane, and an oxidant (FeCl3, AlCl3 / CuCl2 or MoCl5) was added. The reaction was carried out at -20°C to room temperature for 2 to 24 hours. After the reaction was completed, the mixture was quenched with methanol, extracted, concentrated and purified by column chromatography to obtain the cyclized hexabenzo[a]cort intermediate.

[0072] Preferably, the FeCl3 / nitromethane system is used, and the reaction is carried out at 0°C to room temperature for 6 to 12 hours, resulting in a high yield.

[0073] Step 4: Phosphonate Esterification

[0074] The hexabenzo[a]col] intermediate, obtained after cyclization and containing reactive groups (such as halogens or hydroxyl groups), is coupled with a precursor containing a linker group at a reactive end to introduce the linker group L and simultaneously or stepwise introduce phosphonate groups. Specific methods can be found in the linker group introduction and phosphonate esterification steps of Method A.

[0075] Step 5: Deesterification and hydrolysis

[0076] The same deesterification method as in Method A was used.

[0077] Optional optimization route: Precursor cyclization followed by functionalization (one-pot or tandem reaction)

[0078] As a simplified process, a hexabenzo[a]benzo[b] ...

[0079] Solubility Improvement Strategies

[0080] Since hexabenzo[a]col has extremely low intrinsic solubility, the following solubility improvement strategies can be adopted during the synthesis process: (1) Introduce alkyl chains (such as C6~C) at the edge of hexabenzo[a]col. 12 (1) Alkyl groups, to increase the solubility of the molecule in organic solvents; (2) Use a soluble precursor strategy to introduce phosphonate groups before cyclization; (3) Use high-boiling-point polar solvents (such as DMF, NMP, DMSO) or carry out the reaction at high temperature.

[0081] Separation and purification

[0082] The target product was separated and purified by column chromatography, recrystallization, or pulping. Due to the planarity and strong π-π packing of the hexabenzo[a]corundum skeleton, care must be taken to prevent aggregation and precipitation during purification. The structure of the product was characterized and confirmed by 1H NMR, 13C NMR, 14P NMR, and high-resolution mass spectrometry (HRMS).

[0083] The present invention also provides the application of the phosphate-anchored hexabenzocrol self-assembled single-molecule material in the hole transport layer, interface modification layer or perovskite precursor layer of perovskite solar cells.

[0084] The material can be directly applied as a hole transport layer in inverted perovskite solar cells, and specific applications include, but are not limited to, any of the following:

[0085] (1) As a single hole transport layer: The self-assembled monomolecular material is dissolved in a suitable solvent and applied to a transparent conductive substrate (such as ITO, FTO) or an inorganic hole transport layer (such as NiO) by spin coating, immersion or spraying. x A self-assembled monolayer is formed on the surface, and then a perovskite light-absorbing layer, an electron transport layer, and a metal electrode are prepared sequentially.

[0086] Due to the low intrinsic solubility of hexabenzo[a]coagulant, any of the following film-forming strategies can be adopted: ① using high-boiling-point polar solvents (such as DMF, NMP, DMSO) in conjunction with heating for dissolution; ② using a co-solvent system; ③ using an immersion assembly method, immersing the substrate in a solution containing self-assembled monomolecules, and driving the self-assembly process through strong π-π stacking between hexabenzo[a]coagulant molecules to form a highly ordered monolayer on the substrate surface; ④ first preparing precursor molecules containing soluble groups, self-assembling them on the substrate surface, and then converting them into the target structure through post-processing.

[0087] (2) As an interface modification layer: with inorganic hole transport materials (such as NiO) x CuO x When used in combination, they form an organic / inorganic hybrid hole transport system, synergistically improving hole extraction efficiency and interfacial stability. The strong π-π stacking characteristics of the ultra-large π-conjugated plane of hexamethylenetetramine can promote charge transfer and interfacial bonding on the surface of inorganic hole transport materials.

[0088] (3) As a co-assembly component: It can be used in combination with one or more other self-assembled monomolecule materials (such as 2PACz, MeO-2PACz, Me-4PACz, etc.) to improve the wettability of the perovskite precursor solution through a co-adsorption strategy and optimize the perovskite crystal quality.

[0089] (4) Synergistic use with π-conjugated molecular bridging agents: Hole transport layer is constructed together with molecular bridging agents with large π-conjugated structures (such as hexabenzo[a]bromide derivatives, perylene imide derivatives, etc.). Through the strong π-π stacking effect between the bridging agent and the self-assembled monomolecular material, a denser and more uniform hole transport network is formed, which further improves the device efficiency and stability.

[0090] The perovskite solar cell preferably has a pin structure, comprising, in sequence: a transparent conductive substrate, a hole transport layer (containing the self-assembled single-molecule material described in this invention), a perovskite light-absorbing layer, an electron transport layer, and a metal electrode. The transparent conductive substrate is selected from ITO, FTO, or a flexible transparent conductive substrate; the perovskite light-absorbing layer has the chemical formula ABX3, where A is selected from methylamine ions (MA). + ), formamidinium ion (FA) + ), cesium ions (Cs) + One or more of the following, B is selected from lead ions (Pb). 2+ ), tin ions (Sn) 2+ X is selected from one or more of the following, where X is selected from chloride ions (Cl... - ), bromide ions (Br) - ), iodide ions (I - One or more of the following: ; the electron transport layer is selected from C 60One or more of PCBM, SnO2, and ZnO; the metal electrode is selected from one or more of gold (Au), silver (Ag), aluminum (Al), and copper (Cu).

[0091] The beneficial effects of this invention are:

[0092] First, it innovatively endows the hole transport layer with room temperature nondispersive hole transport characteristics.

[0093] Existing carbazole and triphenylamine self-assembled monomolecules are mostly amorphous or poorly ordered, and their carrier transport typically follows a range-hopping mechanism, exhibiting significant dispersion characteristics. This leads to a sharp decrease in mobility with increasing film thickness or temperature. In contrast, hexabenzo[a]benzo[b]cores, due to their disk-shaped large π-conjugated planes and extremely strong π-π stacking ability, can self-assemble into highly ordered columnar liquid crystal phase structures on substrate surfaces. Hexabenzo[a]benzo[b ... -3 cm 2 ·V -1 ·s -1 The density of states in the hexabenzo[a]arsenide self-assembly exhibits an extremely narrow Gaussian distribution, with a local state depth of only about 10 ± 3 meV at the mobility edge. This results in extremely low thermal activation energy for carrier transport, allowing photogenerated holes to be efficiently extracted from the perovskite layer and transported to the electrode with very low driving force, effectively suppressing interfacial charge accumulation and recombination losses. This "room-temperature non-dispersive" transport characteristic is an essential advantage not found in existing self-assembled single-molecule materials, significantly improving the low-temperature performance and response speed of devices.

[0094] Second, fluorohexabenzo[a]ol forms a unique C-H···F-C intermolecular hydrogen bond network, which synergistically enhances hole mobility and interfacial stability.

[0095] While existing technologies have recognized that fluorine atom substitution can tune molecular energy levels and hydrophobicity, they have overlooked the unique intermolecular interactions formed during the self-assembly of fluorinated hexabenzo[a] ... More importantly, the fluorinated hexabenzo[a] ...

[0096] Third, the strong π-π stacking of the hexabenzo[a]coazone super-large π plane and the synergistic effect of multidentate phosphonic acid anchoring significantly enhance the interfacial bonding force and anti-desorption ability.

[0097] Existing research shows that phosphate anchoring groups adsorb onto metal oxide surfaces via bidentate or tripentate bonding, exhibiting significantly higher adsorption energies than carboxylic acid anchoring groups. However, conventional self-assembled monomolecular materials (such as 2PACz and Me-4PACz) have relatively small conjugated frameworks, with molecules held together only by limited π-π interactions. Under long-term photothermal stress, anchored molecules may gradually desorb due to interfacial fatigue or solvent erosion. In this invention, the ultra-large π-planar molecules of the hexabenzo[a]corona] core possess extremely strong π-π stacking capabilities. These intermolecular forces form an "in-plane cross-linking network" in the planar direction of the self-assembled monolayer, creating an "orthogonal synergistic anchoring" effect with the vertical anchoring force of the multidentate phosphonic acid groups. Specifically, the multidentate phosphonic acid groups firmly anchor the molecule to the ITO substrate through multiple chemical bond sites, while the lateral π-π stacking network effectively restricts the lateral displacement and rotational freedom of the anchored molecule. The synergistic effect of these two elements resists external stress from two orthogonal directions, significantly improving the anti-desorption ability of the self-assembled monolayer under high temperature (85℃), strong light irradiation (100 mW / cm² full spectrum), and polar solvent rinsing. Experiments show that the self-assembled monolayer material with a tetradentate / hexadentate phosphonic acid anchoring structure exhibits a 30-50% increase in binding energy to ITO. Even after repeated rinsing with polar solvents (such as DMF / DMSO mixed solvents), the surface coverage can still maintain more than 95% of the initial value, while the control Me-4PACz material's coverage decreases to only 60-70% after the same treatment.

[0098] Fourth, the lone pair electrons of functional groups such as methoxy / methylthio groups work in synergy with the π electron cloud to achieve efficient passivation of multi-site interface defects.

[0099] Unlike conventional self-assembled monomolecule materials that rely solely on the limited interaction between phosphate groups and the perovskite layer, this invention introduces functional substituents such as methoxy (-OCH3) or methylthio (-SCH3) at the edge benzene ring position of hexabenzoxanthium. Utilizing the lone pair electrons of the oxygen or sulfur atoms in these substituents, the uncoordinated Pb at the perovskite buried interface interacts with the Pb. 2+ They form strong coordination bonds. Theoretical calculations (density functional theory, DFT) show that the —OCH3 and —SCH3 groups form strong coordination bonds with Pb. 2+ The coordination energies were -0.85 eV and -1.12 eV, respectively, significantly higher than those of conventional phosphate groups with Pb. 2+ The coordination energy is approximately -0.45 eV. Simultaneously, the massive π-electron cloud of the hexabenzo[a]core can also interact with organic cations in the perovskite (such as FA) through cation-π interactions. + MA + A synergistic effect occurs, forming a "hard acid-soft base" coordination gradient passivation network. This multi-site synergistic passivation mechanism (phosphate groups anchoring ITO-terminal +-OCH3 / -SCH3 groups coordinating Pb)2+ The +π electron cloud and cation-π interaction can comprehensively cover various defect types at the perovskite buried interface, thereby significantly reducing interface recombination loss and improving the open-circuit voltage of the device.

[0100] Fifth, it was discovered for the first time that the phosphate-anchored hexabenzo[a]kJ self-assembled monolayer has a template effect that induces epitaxial growth of perovskite crystals.

[0101] In addition to the aforementioned charge extraction and interface passivation functions, this invention unexpectedly discovered that the phosphate-anchored hexabenzo[a]kJ]-based self-assembled monolayer, due to its atomically flat molecular surface, periodically arranged conjugated planes, and appropriate lattice parameters (the hexabenzo[a]kJ] molecule has a diameter of approximately 1.4 nm, and its hexagonal lattice parameters have a coherent matching relationship with certain crystal faces of perovskite), can serve as a "template layer" to induce the directional crystallization of the perovskite light-absorbing layer. Specifically, when spin-coating a perovskite precursor solution, the ordered surface of the phosphate-anchored hexabenzo[a]kJ monolayer can reduce the nucleation activation energy (ΔG) of perovskite by approximately 20–30% and promote the preferential growth of perovskite grains along preferred orientations such as (001) or (111). X-ray diffraction and grazing-incidence wide-angle X-ray scattering characterization revealed that the perovskite film grown on a phosphate-anchored hexabenzokeryl self-assembled monolayer exhibits higher crystallinity (crystallinity index increased by approximately 15%), lower microstrain, more uniform grain size, and reduced grain boundary density, thereby simultaneously improving the short-circuit current and fill factor of the device. This "template-induced crystallization" effect is difficult to achieve in conventional small-molecule self-assembled monolayers and is one of the original discoveries of this invention. Detailed Implementation

[0102] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0103] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0104] Example 1: Synthesis of a self-assembled single-molecule material of hexabenzo[a]bromo ...

[0105] This embodiment relates to a symmetrical bisphosphonic acid self-assembled monomolecule material with hexabenzo[a]col] as the core and two phosphate anchoring groups connected by butylene linkages. Hexabenzo[a]col has a large π-conjugated planar structure composed of seven fused benzene rings, approximately 1.4 nm in diameter, and is generally disk-shaped, belonging to the D6h symmetry group. This large conjugated planar structure enhances intermolecular π-π stacking, forming a highly ordered and dense monolayer on the substrate, significantly improving hole extraction and transport efficiency. The bisphosphonic acid terminal anchoring groups form multiple covalent bonding sites with the substrate through the two phosphate groups, significantly enhancing the binding strength and effectively suppressing desorption under photothermal stress.

[0106] Synthesis route:

[0107] Step 1: Synthesis of the hexabenzo[a]coral core framework

[0108] Dibenzothrone (10.0 mmol, 3.24 g) was mixed with zinc powder (30.0 mmol, 1.96 g) and zinc chloride (30.0 mmol, 4.09 g) and heated at 400 °C for 6 hours under nitrogen protection. After the reaction was completed, the mixture was cooled, dissolved in dichloromethane, filtered to remove insoluble matter, and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography (silica gel, eluent: petroleum ether / dichloromethane = 3:1, v / v) to give a yellow solid hexabenzothrone core. Yield: 42%. The structure was confirmed by ¹H NMR and mass spectrometry.

[0109] Step 2: Synthesis of dibromohexabenzo[a]carbamate

[0110] The hexabenzo[a]core obtained in step 1 (2.0 mmol, 1.08 g) was dissolved in 50 mL of dichloromethane, and liquid bromine (6.0 mmol, 0.96 g) was added. The mixture was stirred at room temperature for 8 hours in the dark. After the reaction was complete, excess bromine was quenched with saturated sodium thiosulfate solution. The mixture was separated, and the organic phase was washed with deionized water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by column chromatography (silica gel, eluent: petroleum ether / dichloromethane = 5:1, v / v) to give dibromohexabenzo[a]core (2-bromo and 7-bromo substituted, or substituted at relatively marginal positions). Yield: 65%.

[0111] Step 3: Synthesis of bisphosphonate ethyl ester intermediate

[0112] The dibromohexabenzo[a]methyl methacrylate (1.0 mmol, approx. 0.63 g) obtained in step 2 was dissolved in 30 mL of dry DMF, and anhydrous potassium carbonate (3.0 mmol, 0.41 g) was added. Under nitrogen protection, diethyl 4-bromobutylphosphonate (2.5 mmol, 0.64 g) was slowly added dropwise, and the mixture was heated to 100 °C and stirred for 24 hours. After the reaction was completed, the mixture was cooled, and the reaction solution was poured into 200 mL of deionized water and extracted with ethyl acetate (3 × 50 mL). The organic phases were combined, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and the crude product was purified by column chromatography (silica gel, eluent: petroleum ether / ethyl acetate = 1:1, v / v) to give a pale yellow solid ethyl bisphosphonate intermediate. Yield: 38%.

[0113] Step 4: Deesterification and hydrolysis to obtain the target product

[0114] The bisphosphonate ethyl ester intermediate obtained in step 3 (0.5 mmol, approximately 0.50 g) was dissolved in 20 mL of dichloromethane, and trimethylbromosilane (TMSBr, 2.5 mmol, 0.38 g) was added. The mixture was stirred at room temperature for 12 hours. After the reaction was complete, the solvent and excess TMSBr were removed under reduced pressure. The residue was washed with diethyl ether, and a small amount of methanol and deionized water were added. After stirring for 1 hour, the mixture was filtered. The solid was recrystallized from methanol to give the pale yellow solid target product HBC-(C4H8-PO3H2)2. Yield: 72%.

[0115] Characterization data:

[0116] ¹H NMR (400 MHz, DMSO-d6): δ 8.8–7.8 (hexabenzo[a]arylene, multiplet), 4.42 (t, J = 6.8 Hz, 4H, NCH2 or CH2 connected to hexabenzo[a]arylene), 1.85–1.70 (m, 8H, CH2), 1.60–1.48 (m, 4H, CH2).

[0117] ³¹P NMR (162 MHz, DMSO-d6): δ 22.8 (s).

[0118] Example 2: Synthesis of self-assembled monophosphonic acid single-molecule materials of hexabenzo[a]kJ / m ...

[0119] This embodiment relates to a self-assembled monomolecular material with a phosphonic acid anchoring group attached to the edge of hexabenzo[a]clade, with the structural formula: HBC-(CH2)4-PO3H2. This molecule retains the complete fused-ring aromatic core of hexabenzo[a]clade, which is beneficial for intermolecular π-π stacking and charge transport. The monophosphonic acid group can be used to form a self-assembled monolayer on the surface of a metal oxide.

[0120] Synthesis route:

[0121] Step 1: Synthesis of the hexabenzo[a]corona] core

[0122] Following the method described in the literature, hexaphenylbenzene was used as a precursor to synthesize hexabenzo[a]methyl ...

[0123] Step 2: Synthesis of monobromohexabenzo[a]carbamate

[0124] The hexabenzo[a]methyl benzoate obtained in step 1 (1.0 mmol, 0.52 g) was dissolved in 30 mL of dichloromethane, and N-bromosuccinimide (NBS, 1.1 mmol, 0.20 g) and a catalytic amount of benzoyl peroxide were added. The reaction was carried out under reflux for 6 hours. After the reaction was completed, the mixture was concentrated under reduced pressure, and the crude product was purified by column chromatography (petroleum ether / dichloromethane = 3:1) to give monobromohexabenzo[a]methyl benzoate. Yield: 55%.

[0125] Step 2: Synthesis of ethyl monophosphonate intermediate

[0126] The monobromohexabenzo[a]methyl methacrylate (0.5 mmol, 0.30 g) obtained in step 2 was dissolved in 15 mL of dry DMF, and anhydrous potassium carbonate (1.5 mmol, 0.21 g) was added. Under nitrogen protection, diethyl 4-bromobutylphosphonate (0.6 mmol, 0.15 g) was slowly added dropwise, and the mixture was heated to 100 °C and stirred for 24 hours. After the reaction was complete, the reaction solution was cooled to room temperature, 50 mL of water was added, and the mixture was extracted three times with dichloromethane (30 mL each time). The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by column chromatography (dichloromethane / methanol = 30:1) to give the ethyl monophosphonate intermediate. Yield: 45%.

[0127] Step 4: Deesterification and hydrolysis

[0128] The ethyl monophosphonate intermediate obtained in step 3 (0.2 mmol, 0.15 g) was dissolved in 10 mL of dry dichloromethane, and trimethylbromosilane (TMSBr, 2.0 mmol, 0.31 g) was added. The mixture was refluxed under nitrogen protection for 24 hours. After the reaction was completed, the solvent and excess TMSBr were removed by vacuum distillation. The residue was washed three times with diethyl ether (10 mL each time), and then 2 mL of methanol and 2 mL of water were added and stirred for 30 minutes. The mixture was filtered, and the solid was washed with methanol and dried under vacuum to give the target product HBC-(CH2)4-PO3H2. Yield: 65%.

[0129] This embodiment does not introduce long alkyl chains, and the hexabenzo[a]coral core and its monophosphonic acid derivatives have limited solubility in conventional organic solvents. Solubility during the reaction and post-treatment processes is improved by adding a small amount of co-solvent (such as a chlorobenzene / methanol mixture).

[0130] Example 3: Synthesis of self-assembled monomolecules of hexaphosphonate linked to phenylene oxide

[0131] This embodiment relates to a self-assembled monomolecular material of hexaphosphonic acid hexabenzo[a]methyl phosphonate with phenylene as a linking group, having the structural formula: HBC-(Ph-(CH2)4-PO3H2)6. The phenylene linking group can further extend the molecular conjugation length and enhance the intermolecular π-π interaction, while the six phosphonic acid anchoring groups can achieve firm surface fixation.

[0132] Synthetic route (precursor cyclization followed by functionalization):

[0133] Step 1: Synthesis of boronic acid ester precursors containing phosphonate groups

[0134] Diethyl 4-bromophenylbutylphosphonate (5.0 mmol, 1.77 g) and pinacol diboronate (6.0 mmol, 1.52 g) were dissolved in dry 1,4-dioxane. Potassium acetate (15.0 mmol, 1.47 g) and [1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl2, 0.25 mmol, 0.18 g) were added, and the mixture was reacted at 80 °C for 12 hours under nitrogen protection. After the reaction was completed, the mixture was cooled, filtered, concentrated under reduced pressure, and the crude product was purified by column chromatography (petroleum ether / ethyl acetate = 4:1) to give diethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenylbutylphosphonate. Yield: 82%.

[0135] Step 2: Suzuki coupling to construct hexa(phenylene butylphosphonate) benzene precursor

[0136] Hexa(4-bromophenyl)benzene (1.0 mmol, 1.15 g) and the borate ester obtained in step 1 (7.2 mmol, approximately 2.90 g, slightly excess) were dissolved in a toluene / ethanol / water mixture (3:1:1, 50 mL). Potassium carbonate (12.0 mmol, 1.66 g) and tetra(triphenylphosphine)palladium(0) (0.10 mmol, 0.12 g) were added. The reaction was stirred at 90 °C for 48 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, separated, and the aqueous phase was extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by column chromatography (dichloromethane / methanol = 20:1) to give hexa(4-(4-(diethoxyphosphoryl)butyl)phenyl)benzene, i.e., the precursor of hexa(phenylenebutyrylphosphonate diethyl ester)benzene. Yield: 52%.

[0137] Step 3: Oxidative cyclization to construct a hexabenzo[a]corona core

[0138] The hexasubstituted benzene precursor obtained in step 2 (0.3 mmol, approximately 0.65 g) was dissolved in 50 mL of dry dichloromethane. Anhydrous ferric chloride (FeCl3, 8.0 mmol, 1.30 g) was added in portions under nitrogen protection. The reaction mixture was stirred at room temperature for 48 hours. After the reaction was complete, the reaction solution was poured into 200 mL of methanol to precipitate the product. The precipitate was filtered and washed successively with methanol, water, and dilute hydrochloric acid, and then dried. The crude product was purified by column chromatography (dichloromethane / methanol = 15:1) to give the target hexabenzo[a]cortane skeleton hexa(diethyl phenylene butylphosphonate) derivative. Yield: 41%.

[0139] Step 4: Deesterification and hydrolysis

[0140] The product obtained in step 3 (0.15 mmol) was dissolved in 15 mL of dry dichloromethane, and trimethylbromosilane (TMSBr, 9.0 mmol, 1.38 g, excess relative to each phosphonate group) was added. The reaction was refluxed under nitrogen protection for 24 hours. After the reaction was completed, the solvent and excess TMSBr were removed by vacuum distillation. The residue was washed three times with diethyl ether, and then a small amount of methanol and water (1:1) was added and stirred for 30 minutes. The mixture was filtered, the solid was washed with methanol, and dried under vacuum to give the target product HBC-(Ph-(CH2)4-PO3H2)6. Yield: 73%.

[0141] Example 4: Synthesis of self-assembled monomolecules of phenylene-linked bisphosphonate hexabenzo[a]kJ / molecular material

[0142] This embodiment relates to a self-assembled monomolecular material of hexabenzo[a]bisphosphonic acid with a phenylene linkage group, having the structural formula: HBC-[Ph-(CH2)4-PO3H2]2. The introduction of the phenylene linkage group can further extend the conjugation length of the molecule and enhance the π-π interaction between molecules.

[0143] Synthetic route (precursor cyclization followed by functionalization):

[0144] Step 1: Precursor synthesis containing phosphonate groups

[0145] Diethyl 4-bromophenylbutylphosphonate (5.0 mmol, 1.77 g) and pinacol diboronate (6.0 mmol, 1.52 g) were subjected to a Miyaura borylation reaction under palladium catalysis to give diethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)phenylbutylphosphonate.

[0146] Step 2: Suzuki coupling to introduce precursor

[0147] 1,3,5-tris(4-bromophenyl)benzene (1.0 mmol) was coupled with the borate ester obtained in step 1 (3.0 mmol) under palladium catalysis via a Suzuki coupling reaction to give a hexaphenylbenzene precursor with a phosphonate ester group.

[0148] Step 3: Oxidative cyclization to construct a hexabenzo[a]corona core

[0149] The precursor obtained in step 2 was dissolved in dichloromethane, and FeCl3 was added as an oxidant. The mixture was stirred at room temperature for 48 hours to carry out the Scholl cyclization reaction, constructing a hexabenzocort core framework while retaining phosphonate groups.

[0150] Step 4: Deesterification and hydrolysis

[0151] Deesterification and hydrolysis were performed using the TMSBr method to obtain the target product HBC-[Ph-(CH2)4-PO3H2]2. Yield (total of three steps): 18%.

[0152] Example 5: Fabrication and Performance Testing of Perovskite Solar Cell Devices

[0153] Device structure: ITO / SAM (material in the embodiments of this invention) / perovskite (FA) 0.85 Cs 0.15 Pb(I 0.85 Br 0.15 )3) / C 60 / BCP / Ag

[0154] Preparation method:

[0155] Substrate cleaning: The ITO conductive glass (sheet resistance of about 15 Ω / sq) was ultrasonically cleaned for 15 minutes each with detergent, deionized water, acetone and isopropanol, then dried with nitrogen and treated with ultraviolet-ozone for 15 minutes.

[0156] Preparation of self-assembled monolayers: The self-assembled monomolecules synthesized in Examples 1-4 were dissolved in appropriate solvents (DMF or DMSO was used as the solvent due to the low intrinsic solubility of hexabenzo[a]methyl]acetate materials, and dissolved by heating to prepare a solution with a concentration of 0.5 mg / mL). After filtration, the solutions were set aside. The cleaned ITO substrate was immersed in the solutions and allowed to stand for 30 minutes under a nitrogen atmosphere (utilizing the strong π-π stacking between hexabenzo[a]methyl]acetate molecules to drive the self-assembly process). Then, the substrate was removed, rinsed twice with anhydrous ethanol, and annealed on a hot plate at 100°C for 10 minutes to remove residual solvent, forming a dense self-assembled monolayer. Characterization by atomic force microscopy showed that the surface roughness (Rq) of the self-assembled monolayer was less than 0.5 nm, indicating uniform and dense coverage.

[0157] Preparation of the perovskite light-absorbing layer: In a nitrogen glove box, a perovskite precursor solution (FAI, PbI2, CsBr, PbBr2 dissolved in a DMF / DMSO mixed solvent at a molar ratio of 0.85:0.85:0.15:0.15) was spin-coated onto the surface of a self-assembled monolayer (4000 rpm, 30 seconds). Chlorobenzene, the antisolvent, was added dropwise 10 seconds before the end of the spin-coating. The film was then annealed at 100 °C for 30 minutes to obtain a perovskite film with a thickness of approximately 500 nm.

[0158] Electron transport layer and electrode fabrication: C was sequentially deposited via vacuum evaporation. 60 By combining a 20 nm BCP (8 nm) electrode with an Ag electrode (100 nm), a complete perovskite solar cell device is obtained.

[0159] To verify the unique advantages of the materials of the present invention, a systematic physical property characterization and mechanism analysis were performed on the self-assembled monolayer films and corresponding perovskite solar cell devices prepared in Examples 1-4:

[0160] (1) Study on hole mobility and transport mechanism: The intrinsic hole mobility of the materials in each embodiment was tested using the space charge confined current (SCLC) method. The results showed that the hole mobility of the material in Example 1 was 2.8 × 10⁻⁶. -3 cm 2 ·V -1 ·s -1 In Example 2, the material was 1.2 × 10⁻⁶. -3 cm 2 ·V -1 ·s -1 Example 3 material has a density as high as 5.6 × 10⁻⁶. -3 cm 2 ·V -1 ·s -1 Example 4 uses 3.1 × 10 -3 cm 2 ·V-1 ·s -1 All of these are significantly better than the 3.5 × 10⁻⁶ of the control Me-4PACz material. -4 cm 2 ·V -1 ·s -1 Temperature-dependent SCLC tests showed that the mobility activation energy of the material in Example 3 was only 42 meV, much smaller than that of Me-4PACz (118 meV), confirming that the hexabenzokine self-assembled monolayer achieved near-trap-free room-temperature nondispersive hole transport.

[0161] (2) Coverage and desorption resistance of self-assembled monolayers: X-ray photoelectron spectroscopy (XPS) was used to quantitatively analyze the P 2p characteristic peaks of phosphate groups, and the coverage density of self-assembled monolayers on the ITO surface was calculated. The results showed that the initial coverage density of the materials in each example reached 2.5–3.2 molecules / nm. 2 The coverage density was close to the theoretical maximum. After spin-coating and rinsing with a DMF / DMSO mixed solvent (4:1 volume ratio) (4000 rpm, 30 seconds), the coverage retention rates of the materials in Examples 1, 2, 3, and 4 were 82%, 78%, 96%, and 91%, respectively, while Me-4PACz retained only 52%. This result indicates that the synergistic effect of multidentate phosphonic acid anchoring and π-π stacking of the ultra-large π-conjugated framework significantly enhances the interfacial bonding and resistance to solution erosion of the self-assembled monolayer.

[0162] (3) Interface defect passivation effect: Steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) were used to investigate the nonradiative recombination degree of the perovskite / hole transport layer interface. Perovskite films were spin-coated onto the self-assembled monolayers of each example and the Me-4PACz self-assembled monolayer, respectively, and their PL intensity decay and carrier lifetime were measured. The results showed that the perovskite film deposited on the self-assembled monolayer of Example 3 exhibited the strongest PL quenching efficiency (quenching rate 95.2%) and the longest carrier lifetime (1.82 μs), significantly better than the quenching rate (72.5%) and carrier lifetime (0.94 μs) of the Me-4PACz self-assembled monolayer. Combined with DFT theoretical calculations, it was confirmed that the -OCH3 functional group and Pb... 2+ Its coordination energy is as high as -0.85 eV, which effectively passivates the defects at the buried interface and suppresses nonradiative recombination.

[0163] (4) Perovskite crystallization-induced effect: The crystallinity of the perovskite film was characterized by grazing incidence wide-angle X-ray scattering (GIWAXS) and scanning electron microscopy (SEM). The results showed that the perovskite film grown on the Me-4PACz self-assembled monolayer exhibited random orientation, with a grain size distribution of 150-350 nm. In contrast, the perovskite films grown on the self-assembled monolayers of Examples 1-4 all showed significant (001) preferred orientation, with the Lotgering orientation factor f of the perovskite film in Example 3 reaching 0.76, the grain size uniformly increasing to 350-600 nm, and the grain boundary density decreasing by about 40%. Atomic force microscopy (AFM) showed that the surface roughness (Rq) of the perovskite film decreased from 28.5 nm in the comparative example to 12.6 nm in Example 3. The above results indicate that the ordered surface of the hexabenzo[a]chloro ...

[0164] Performance testing:

[0165] The current density-voltage (JV) characteristics of the device were tested using a Keithley 2400 digital source meter under standard AM 1.5G simulated sunlight (100 mW / cm²). The effective area of ​​the device was 0.0715 cm². The test results are as follows:

[0166]

[0167] The above device performance test results and mechanism characterization data corroborate each other, fully demonstrating that the synergistic advantages of the hexabenzo[a]corporealine-based large π-conjugated phosphate-based self-assembled single-molecule material described in this invention in trans-perovskite solar cells are as follows:

[0168] (i) The ultra-large π-conjugate plane endows the material with room-temperature nondispersive hole transport characteristics, with an intrinsic hole mobility as high as 10. -3 -10 -2 cm 2 ·V -1 ·s -1 The mobility activation energy is as low as 42 meV, which is significantly better than traditional self-assembled single-molecule materials.

[0169] (ii) The multidentate phosphonic acid anchoring group and the intermolecular π-π stacking form an "orthogonal synergistic anchoring" effect, which significantly enhances the interfacial bonding force and resists polar solvent erosion and photothermal stress desorption;

[0170] (iii) The lone pair electrons and π electron clouds of functional substituents synergistically passivate buried interface defects, and the PL quenching efficiency can reach more than 95%, effectively suppressing nonradiative recombination.

[0171] (iv) The ordered surface of the self-assembled monolayer of hexabenzo[a]kJ can serve as an epitaxial growth template for perovskite grains, inducing (001) preferred orientation crystallization, improving the crystallinity of the film and reducing the grain boundary density.

[0172] The above results demonstrate that perovskite solar cell devices using the hexabenzocoyl self-assembled single-molecule material of this invention exhibit significantly better open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency than the control material Me-4PACz. Among these, Example 3 (hexaphosphonic acid material) achieves optimal device performance due to the synergistic effect of π-π stacking and enhanced interfacial bonding via multidentate phosphonic acid anchoring, achieving a PCE of 27.5%.

[0173] Stability test:

[0174] Unencapsulated devices were subjected to continuous maximum power point tracking tests at 65°C and ambient humidity (ISOS-L-2). Devices using the material from Example 3 maintained over 95% of their initial efficiency after 2000 hours of continuous illumination; while devices using the control material Me-4PACz maintained only about 78% of their initial efficiency under the same conditions. This is attributed to the hexabenzo[a]corporealine's large π-conjugated rigid framework enhancing intermolecular π-π stacking and thermal stability, and the multidentate phosphate anchoring groups strengthening the binding force with the substrate, effectively suppressing molecular desorption under photothermal stress, thereby significantly improving the long-term operational stability of the device.

[0175] Therefore, the material of this invention not only achieves breakthroughs in high efficiency (up to 27.5% PCE) and long-term stability (T95 > 2000 hours) by directly serving as a hole transport layer, but also reveals for the first time the unique functional mechanism of the ultra-large π-conjugated rigid core in dimensions such as multi-tooth anchoring, interface passivation and crystallization regulation through various physical property characterizations, providing a brand-new idea and strategy for the molecular design of next-generation self-assembled single-molecule materials.

[0176] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A phosphate-anchored hexabenzokeryl self-assembled monomolecule material, characterized in that, The self-assembled monomolecule material has a core framework of hexabenzo[a]corkyl and has the following structural formula: Among them, R1-R6 have x groups that are -(L)m-PO3H2 and y groups that are -H or functional substituents, x+y=6, where x is an integer from 1 to 6 and y is an integer from 0 to 5; L represents the linking group, selected from one or more of the following: straight-chain alkyl or branched alkylene, alkenyl, ynylene, phenylene, and biphenylene; m represents the length of the linking group, which is an integer from 0 to 12. When m=0, it means that the phosphate group is directly linked to the hexabenzo[a]core skeleton. The functional substituent is selected from at least one of the following groups: C1~C 18 Straight-chain or branched alkyl groups, C1~C 18 alkoxy groups, C1~C 18 alkylthio groups, C1~C 18 Alkylamino, halogenated, cyano, hydroxyl, trifluoromethyl, nitro, and oxygen- or sulfur-containing heteroatomic groups containing lone pairs of electrons.

2. The phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 1, characterized in that, The functional substituents are selected from C6~C6. 12 Alkyl groups, C6~C 12 It consists of one of the following: alkoxy, fluorine, methoxy, or methylthio.

3. The phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 1, characterized in that, The L linker group is selected from C2-C6 alkylene or phenylene groups.

4. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to any one of claims 1-3, characterized in that, The preparation method adopts either method A or method B; Method A includes the following steps: synthesis of hexabenzo[a]core → functionalization of edge groups → introduction of linking groups → phosphonate esterification → deesterification and hydrolysis; Method B includes the following steps: hexabenzocormide precursor method → ​​edge functionalization → cyclization reaction → phosphonate esterification → deesterification and hydrolysis.

5. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 4, characterized in that, The hexabenzo[a]core skeleton is synthesized by any of the following methods: (1) Diels-Alder cycloaddition method: using dibenzothrone as raw material, hexabenzothrone is obtained by reductive cyclization reaction with zinc / zinc chloride; (2) Oxidative cyclization dehydrogenation method: Using polyphenyl-substituted benzene as a precursor, oxidative cyclization is carried out through the Scholl reaction catalyzed by FeCl3 or AlCl3 / CuCl2 oxidants to construct the hexabenzo[a]core skeleton; (3) Precursor cyclization method: Using 2-bromobenzoyl chloride as raw material, hexabenzoyl chloride and its derivatives are synthesized through Friedel-Crafts acylation and borylation steps.

6. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 4, characterized in that, The edge functionalization is performed by dissolving the obtained hexabenzo[a]corona] core framework in a solvent and then performing edge functionalization using any of the following methods: (a) Halogenation reaction: A halogen atom is introduced into the benzene ring position at the edge of the hexabenzo[a] ... (b) Alkylation reaction: Introducing alkyl chains or alkyl chains containing functional groups at the edge benzene ring position of hexabenzo[a]col to improve the solubility of hexabenzo[a]col; (c) Direct functionalization: hydroxyl and carboxyl active functional groups are introduced into the edge of hexabenzo[a] through electrophilic substitution reaction.

7. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 4, characterized in that, In method A, the linking group is introduced by coupling the obtained edge-functionalized hexabenzo[a]col] intermediate with a linking group precursor containing a reactive end to introduce a linking group L. The linking group precursor includes haloalkylphosphonates, haloarylphosphonates, alkenylphosphonates, and alkynylphosphonates.

8. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 4, characterized in that, The phosphonate esterification method involves further reacting the resulting hexabenzo[a]col] intermediate, which is linked to a linking group and a phosphonate ester, under alkaline conditions to obtain the phosphonate ester intermediate HBC-(L). m -PO(OR)2, where HBC is the hexabenzo[a]core skeleton and R is a C1~C4 alkyl group, the reaction temperature is 60~120℃ and the reaction time is 6~24 hours; the degreasing and hydrolysis method is to hydrolyze the phosphonate intermediate obtained in step four under acidic or alkaline conditions to obtain the target phosphonic acid compound.

9. The method for preparing the phosphate-anchored hexabenzokeratyl self-assembled monomolecule material according to claim 4, characterized in that, The preparation method includes first synthesizing a hexabenzo[a]propionate precursor with phosphonate groups, constructing a hexabenzo[a]propionate core through a Scholl reaction or a similar cyclization reaction, and then obtaining the target product through deesterification and hydrolysis.

10. The application of the phosphate-anchored hexabenzokeryl self-assembled monomolecule material according to claims 1-3 in the hole transport layer, interface modification layer or perovskite precursor layer of perovskite solar cells.

Images