A tricyclic fused hole transport material, perovskite photovoltaic device and preparation method

Abstract

The present application relates to a kind of tricyclic fused hole transport material, perovskite photovoltaic device and preparation method, the structural formula of hole transport material is;In the formula: R1, R2, R3 each independently selected from hydrogen, alkyl, alkoxy, aromatic group, halogen group, carboxyl, trimethoxysilyl one or more combinations;R4, R5, R6, R7, R8 each independently selected from hydrogen, cyano, carboxyl, amino, halogen group, nitro, hydroxyl, alkyl, sulfonic acid group, alkoxy, trimethoxysilyl one or more combinations.The material is realized conjugated structure with thieno ring-pyrrolothiophene as molecular base, constructs the channel of hole fast transmission, guides molecular ordered accumulation, reduces scattering and trap in hole transport process, improves charge transport performance;By thieno carbazole structure adjustment electron cloud distribution, realizes energy level matching.

Description

Technical Field

[0001] This invention relates to a tricyclic fused hole transport material, a perovskite photovoltaic device, and a preparation method thereof, belonging to the field of photovoltaic materials. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental problems, the development of clean and renewable energy has become a core issue for achieving sustainable development. Solar energy, as one of the most abundant and widely distributed clean energy sources, has always been a focus of attention for the scientific and industrial communities in its efficient utilization. Among numerous photovoltaic technologies, perovskite solar cells (PSCs) have become a research hotspot in the energy field over the past decade due to their astonishing development speed and enormous application potential. Since its first report in 2009, the photoelectric conversion efficiency of perovskite solar cells has soared from the initial 3.8% to 26.1% today, approaching the theoretical limit of traditional silicon-based solar cells. Furthermore, its low-cost solution preparation processes (such as spin coating and inkjet printing) give it unique advantages in fields such as flexible photovoltaics and building-integrated photovoltaics.

[0003] Hole transport materials (HTMs) play a crucial role in the core structure of perovskite solar cells. Their main function is to efficiently extract photogenerated holes from the perovskite layer and suppress electron-hole recombination, directly affecting the cell's open-circuit voltage, short-circuit current, and fill factor. Currently, commonly used hole transport materials can be divided into two main categories: inorganic and organic materials. Inorganic materials such as NiOx and CuI, while possessing high stability and low cost, suffer from low hole mobility and poor interfacial contact, limiting their application in high-efficiency devices. In contrast, organic hole transport materials, with their advantages of highly designable molecular structures, high hole mobility, and easily tunable energy level matching with the perovskite layer, have become key materials for constructing high-performance perovskite solar cells.

[0004] However, current mainstream organic hole transport materials still face numerous challenges. Firstly, most organic hole transport materials rely on dopants (such as lithium salts and cobalt salts) to improve conductivity. However, the doping process can introduce side effects such as ion migration and exacerbate hydrolysis and oxidation, reducing device stability. Secondly, agglomeration easily occurs during film formation, causing pinholes in the deposited perovskite film, affecting film quality and consequently conductivity and stability. Thirdly, there is the energy level difference between perovskite and hole transport materials; poor energy level matching leads to high carrier transport losses and low open-circuit voltage. These problems have become significant bottlenecks hindering the industrialization of perovskite solar cells. Summary of the Invention

[0005] To address the issues of poor film uniformity or low open-circuit voltage in perovskite solar cells caused by energy level mismatch in existing organic hole transport materials, this invention provides a tricyclic fused hole transport material. This material constructs a stable conjugated structure based on a thienocyclic-pyrrolothiophene molecular substrate, which not only establishes a channel for rapid hole transport but also induces ordered molecular stacking, promoting uniform growth of the perovskite film. This reduces scattering and trapping effects during hole transport, thereby improving charge transport performance. Furthermore, the thienocarbazole structure in the material effectively modulates the molecular electron cloud distribution, achieving precise matching of the energy levels of the perovskite active layer, ultimately enabling the device to achieve a higher open-circuit voltage.

[0006] The technical solution adopted in this invention is: a tricyclic condensed hole transport material, with the following structural formula:

[0007] ;

[0008] In the formula: R1, R2, and R3 are each independently selected from one or more combinations of hydrogen, alkyl, alkoxy, aromatic, halogen, carboxyl, and trimethoxysilyl; R4, R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen, nitro, hydroxyl, alkyl, sulfonic acid, alkoxy, and trimethoxysilyl.

[0009] Preferably, the groups of R1-R8 satisfy one or more of the following combinations:

[0010] R1 is selected from one or more combinations of hydrogen, alkyl, alkoxy, aromatic, halogen, carboxyl, and trimethoxysilyl groups;

[0011] R2 is selected from one or more combinations of hydrogen, alkyl, alkoxy, aromatic, halogen, carboxyl, and trimethoxysilyl groups;

[0012] R3 is selected from one or more combinations of hydrogen, alkyl, alkoxy, halogen, carboxyl, and trimethoxysilyl groups;

[0013] R4 is selected from one or more combinations of hydrogen, cyano, carboxyl, amino, alkoxy, halogen, alkyl, and trimethoxysilyl groups;

[0014] R5 is selected from one or more combinations of hydrogen, cyano, amino, nitro, carboxyl, hydroxy, alkoxy, sulfonic acid, trimethoxysilyl, and halogen groups;

[0015] R6 is one or more of the following groups: hydrogen, cyano, amino, nitro, carboxyl, hydroxy, alkoxy, sulfonic acid, trimethoxysilyl, and halogen.

[0016] R7 is one or more of the following groups: hydrogen, cyano, amino, nitro, carboxyl, hydroxy, alkoxy, sulfonic acid, trimethoxysilyl, and halogen.

[0017] R8 is selected from one or more combinations of hydrogen, cyano, amino, nitro, carboxyl, hydroxyl, alkoxy, sulfonic acid, trimethoxysilyl, and halogen groups.

[0018] Preferably, R1 is one of hydrogen, aromatic group, methyl group, and chlorine atom; R2 is one of hydrogen, methyl group, and chlorine atom; R3 is one of hydrogen, chlorine atom, and carboxyl group; R4 is one of hydrogen, cyano group, fluorine atom, amino group, iodine atom, and chlorine atom; R5 is one of hydrogen, methoxy group, cyano group, and chlorine atom; R6 is one of hydrogen, cyano group, chlorine atom, and methoxy group; R7 is one of hydrogen and chlorine atom; and R8 is one of hydrogen, carboxyl group, chlorine atom, sulfonic acid group, and trimethoxysilyl group. Preferably, R1 is one of -H, -C6H5, -CH3, and -Cl; R2 is one of -H, -CH3, and -Cl; R3 is one of -H, -Cl, and -CH2COOH; R4 is one of -H, -CN, -F, -NH2, -I, and -Cl; R5 is one of -H, -OCH3, -CN, and -Cl; R6 is one of -H, -CN, -Cl, and -OCH3; R7 is one of -H and -Cl; and R8 is one of -H, -COOH, -(CH2)5SO3H, -(CH2)4SO3H, -Si(OCH3)3, -(CH2)4SO3H, and -Cl.

[0019] Preferably, at least two substitution sites in R1-R8 are cyano and methoxy, or / and at least two substitution sites in R1-R8 are amino and cyano.

[0020] In another preferred embodiment, R1 in this invention is selected from one or more combinations of -H, -CH3, -Cl, -OCH3, -OC2H5, C1-C10 alkyl, -COOH, and -Si(OCH3)3; R2 is selected from one or more combinations of -C6H5, -OCH3, -OC2H5, C1-C10 alkyl, -COOH, and -Si(OCH3)3; R3 is selected from one or more combinations of -OCH3, -OC2H5, -CH2COOH, C1-C10 alkyl, -COOH, and -Si(OCH3)3; and R4 is selected from -CN, -NH2, ... -F, -Cl, -Br, -I, C1-C10 alkyl, -COOH, -Si(OCH3)3; R5, R6, R7 are selected from one or more combinations of -F, -Cl, -Br, -I, C1-C10 alkyl, -SO3H, -COOH, -Si(OCH3)3, -CN, -NH2, -OCH3, -OC2H5, -C6H5, -H, -CH3, -Cl; R8 is selected from one or more combinations of -F, -Cl, -Br, -I, C1-C10 alkyl, -SO3H, -COOH, -Si(OCH3)3, -CN, -NH 2、 One or more combinations of -OCH3, -OC2H5, -C6H5, -H, -CH3, -Cl, and -CH2COOH.

[0021] This invention also provides a method for preparing tricyclic fused and hole transport materials. The preparation method is illustrated using two of these materials as examples. Those skilled in the art can obtain preparation methods for other compounds by referring to this method. One of the example materials has the following structural formula:

[0022] The preparation method is as follows:

[0023] S01 uses a starting material containing an amino group and a thiophene ring as raw material, and reacts with 1,3-propanediol in the presence of p-nitrophenol and sulfuric acid to obtain compound (1).

[0024] Compound (1) of SO2 was brominated to give compound (2);

[0025] Compound (2) of SO3 was reacted with bis-pinacol boronic acid ester to obtain compound (3) via a boronic acid esterification reaction.

[0026] Compound (3) of SO4 was reacted with 4-bromo-3-aminobenzonitrile via a Suzuki coupling reaction to give compound (4).

[0027] Compound (4) of S05 undergoes alkylation with bromobutane and further cyclization to obtain compound (5);

[0028] The target compound was obtained by reacting compound S06 (5) with sodium triisobutylborohydride;

[0029] The compounds (1), (2), (3), (4), and (5) are, in order: , , , , .

[0030] The structural formula of Example Material 2 is:

[0031] The preparation method is as follows:

[0032] The specific synthetic route can be divided into the following steps:

[0033] S01 uses a starting material containing amino and thiophene rings as raw material, and reacts with 1,3-propanediol and cyclizes it to obtain compound (1).

[0034] Compound (1) of SO2 was brominated to give compound (2);

[0035] Compound (2) of SO3 undergoes a borate esterification reaction with bis-pinacol boronic acid ester under the action of a catalyst to obtain compound (3).

[0036] Compound (3) of SO4 was reacted with aromatic ring compounds containing bromine, iodine and bromoalkyl groups via a Suzuki coupling reaction to obtain compound (4);

[0037] Compound (4) of S05 undergoes alkylation and cyclization with bromobutane to obtain compound (5);

[0038] The target compound was prepared by reacting compound S06 (5) sequentially with sodium triisobutylborohydride, methanol and water.

[0039] Compounds (1), (2), (3), (4), and (5) are, in order: , , , , .

[0040] This invention also provides a perovskite photovoltaic device that uses the aforementioned material as the hole transport material. The perovskite photovoltaic device includes a conductive substrate, a hole transport layer, a perovskite layer, and an electron transport layer. The perovskite layer is made of perovskite material, wherein A in the perovskite material ABX3 is formamidinium ion, methylamine ion, or Cs. +One or more combinations of the following, where B is lead ion and C is one or a combination of two of iodide ion, bromide ion, and chloride ion. Preferably, the photovoltaic device includes a conductive substrate, a hole transport layer, a perovskite layer, a modification layer, and an electron transport layer, arranged sequentially. The modification layer material is ethylenediamine dihydroiodide, and the precursor materials for the perovskite material are lead iodide, formamidinium hydroiodate, lead bromide, and formamidinium hydrobromide. The structural formula of the hole transport layer material is:

[0041] .

[0042] Furthermore, the present invention provides a method for fabricating the above-mentioned perovskite photovoltaic device, comprising the following steps:

[0043] S01 Obtain the substrate;

[0044] SO2 is used to prepare the hole transport layer;

[0045] SiO3 was used to prepare the perovskite layer;

[0046] Preparation of the SO4 modified layer;

[0047] S05 is used to prepare an electron transport layer;

[0048] Electrode layers were prepared using S06;

[0049] The hole transport layer material comprises a tricyclic condensate and a hole transport material, and the structural formula of the tricyclic condensate and the hole transport material is as follows:

[0050] ;

[0051] In the formula: R1, R2, and R3 are each independently selected from one or more combinations of hydrogen, alkyl, alkoxy, aromatic, halogen, carboxyl, and trimethoxysilyl; R4, R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen, nitro, hydroxyl, alkyl, sulfonic acid, alkoxy, and trimethoxysilyl.

[0052] Preferably, a metal oxide, such as ITO or FTO, is disposed on the side of the substrate facing the hole transport layer. The hole transport layer is prepared by a solution method, in which a tricyclic fused hole transport material is dissolved in an organic solvent to obtain a hole transport layer precursor solution. The hole transport layer precursor solution is then coated onto the side of the substrate with the metal oxide, annealed, and a film is formed. The concentration of the tricyclic fused hole transport material in the hole transport layer precursor solution is 0.5~1.5 mg / mL.

[0053] The beneficial effects of this invention include: the tricyclic fused hole transport material of this invention contains three ring systems: a sulfur heterocycle, a benzene ring, and a phosphate group. The conjugated skeleton formed by the mutual fusion of shared edges not only greatly expands the electron delocalization range but also improves the chemical stability of the molecule itself. The phosphate group at the end is anchored to the surface of the electrode substrate by strong chemical bonds, enabling the hole transport material to achieve highly uniform self-assembly on the substrate, filling the interfacial gaps that are prone to occur in traditional organic transport layers and improving the charge transport capability.

[0054] In this invention, the tricyclic fused conjugated framework forms an ordered and continuous π-π stacking network through self-assembly. This conjugated network can precisely control the HOMO energy level by adjusting the heterocyclic substituents to match the perovskite valence band, compressing the hole transport barrier to within 0.2 eV and accelerating the rapid extraction of charge carriers from the perovskite active layer to the electrode. On the other hand, its own bandgap characteristics can also act as an "electron barrier," forming a dense interface layer to block the back diffusion of electrons to the electrode. From the two dimensions of "accelerating forward transport + blocking reverse loss," the nonradiative recombination at the electrode-perovskite interface is synergistically suppressed, thereby increasing the open-circuit voltage and thus achieving a significant improvement in the photoelectric conversion efficiency of the battery.

[0055] This invention can also achieve synergistic effects of multiple functional groups through multiple modifiable sites in the molecular structure, finely adjust the HOMO energy level of the material, form a good energy level match with the photoactive layer, and at the same time construct a channel that is conducive to the rapid migration of holes, enabling efficient transport of holes from the photoactive layer to the electrode, reducing charge recombination, and improving the photoelectric conversion efficiency of photovoltaic devices.

[0056] The device in this invention achieves energy level matching between the perovskite material and the hole transport material by regulating their respective energy levels. Furthermore, the hole transport material guides the perovskite material to form a uniform film, thereby improving the film quality and ultimately enhancing the device efficiency.

[0057] This invention achieves energy level matching between perovskite materials, hole transport materials, and electron transport materials, thereby suppressing reverse carrier transport and improving carrier transport efficiency.

[0058] The hole transport material in this invention has good chemical stability and film-forming properties, as well as good interfacial compatibility with the perovskite layer. It can inhibit the degradation of perovskite, reduce the impact of environmental factors on battery performance, and enable the battery to maintain good performance under long-term light, high temperature, high humidity and other conditions, thus extending the battery's service life.

[0059] The hole transport material in this invention can still have good conductivity even without doping and has good solution processing performance. It is suitable for the preparation of large-area perovskite thin film devices, which helps to reduce production costs and promote the industrialization of perovskite solar cells and related technologies. Attached Figure Description

[0060] Figure 1 H-NMR spectrum of Material 1;

[0061] Figure 2 H-NMR spectrum of material 2;

[0062] Figure 3 H-NMR spectrum of material 3;

[0063] Figure 4 Fourier transform infrared (FT-IR) spectra of materials 1, 2, and 3;

[0064] Figure 5 JV curves for Comparative Example 1 and Example 4;

[0065] Figure 6 (a) is a SEM image of the perovskite layer surface in Comparative Example 1, and (b) is a SEM image of the perovskite layer surface in Example 4.

[0066] Figure 7 JV curves for Comparative Example 2 and Example 5;

[0067] Figure 8 (a) is a surface SEM image of the perovskite layer in Comparative Example 2, and (b) is a surface SEM image of the perovskite layer in Example 5.

[0068] Figure 9 JV curves for Comparative Example 3 and Example 6;

[0069] Figure 10 (a) is a surface SEM image of the perovskite layer in Comparative Example 3, and (b) is a surface SEM image of the perovskite layer in Example 6. Detailed Implementation

[0070] The present invention is described in more detail below, but it should not be construed as limiting the scope of protection of the invention to the following description. Unless otherwise specified, any range described in the present invention includes end values, any values ​​between end values, and any sub-ranges formed by end values ​​or any values ​​between end values. There are no particular limitations on the purity of any raw materials used in the present invention; however, analytical grade materials are preferred. The sources and abbreviations of all raw materials used in the present invention are conventional sources and abbreviations in the art, and are clearly understood within the scope of their relevant uses. Those skilled in the art can obtain them from commercially available sources or prepare them using conventional methods based on the abbreviations and corresponding uses.

[0071] "At least one" means one or more, while "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0072] Those skilled in the art will understand that perovskite materials are represented by the general formula ABX3, wherein A is at least one monovalent cation, such as MA. + FA + Cs + 、Rb + In this case, B is at least one divalent cation, such as Ca. 2+ Pb 2+ Sn 2+ Cu 2+ Ga 2+ And X is at least one anion, such as I - ,Br - Cl - F - SCN - When a perovskite comprises more than one monovalent cation, the different monovalent cations can be distributed at site A in an ordered or disordered manner. When a perovskite comprises more than one divalent cation, the different divalent cations can be distributed at site B in an ordered or disordered manner. When a perovskite comprises more than one monovalent anion, the different monovalent anions can be distributed at site X in an ordered or disordered manner.

[0073] The structural formula of the tricyclic condensed hole transport material proposed in this invention is as follows:

[0074] Overall structural formula.

[0075] In the formula: R1, R2, and R3 are each independently selected from one or more combinations of hydrogen, alkyl, alkoxy, aromatic, halogen, carboxyl, and trimethoxysilyl groups, and R1, R2, and R3 may be the same or different; R4, R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen, nitro, hydroxyl, alkyl, sulfonic acid, alkoxy, and trimethoxysilyl groups, and R4, R5, R6, R7, and R8 may be completely the same, partially the same, or completely different. The "one or more combinations" mentioned refers to the possibility of choosing one of them, such as R1 being an alkyl group and R2 being a phenyl group, or it can be a combination of multiple groups, such as R1 being a combination of an alkyl group and an aromatic group—benzyl, and R2 being a combination of an aromatic group and a halogen group—bromophenyl.

[0076] The molecular structure of this invention contains a cyclopentane-thiophene-pyrrole tricyclic fused system. Firstly, this system forms a conjugated π-electron system, delocalizing charge carriers within the molecule and constructing a channel for rapid hole transport, reducing the migration resistance of holes within the molecule, increasing hole mobility, and accelerating charge conduction within the hole transport layer. Secondly, the rigid conjugated thiophene ring structure facilitates orderly molecular stacking during film formation, reducing scattering and trapping during hole transport and lowering hole transport resistance. Thirdly, the pyrrole ring regulates the electron cloud distribution of the molecule, enabling energy level matching between the hole transport material and perovskite materials. Fourthly, the nitrogen heterocycle increases the rigidity and chemical stability of the molecule, reducing photodegradation and oxidative degradation of the material, thus extending the device's lifespan. Fifthly, the S atom in the framework thiophene ring forms a coordinate bond with Pb²⁺, and simultaneously forms hydrogen bonds with halide ions through amino and cyano groups.

[0077] This invention introduces different functional groups at positions R1-R8 of the core framework to adjust the energy level structure of the hole transport material so that it matches the energy level of the perovskite material, thereby achieving passivation of multiple types of defects, multi-site anchoring with the substrate, and enhancing the bonding force between the hole transport material and the substrate.

[0078] In one embodiment, R1 in this invention is selected from one or more combinations of hydrogen, alkyl, alkoxy, halogen group, carboxyl, and trimethoxysilyl; R2 is selected from one or more combinations of hydrogen, aromatic group, alkoxy, carboxyl, and trimethoxysilyl; R3 is selected from one or more combinations of hydrogen, alkyl, alkoxy, halogen group, carboxyl, and trimethoxysilyl; R4 is selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen group, alkyl, alkoxy, and trimethoxysilyl; R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, amino, nitro, carboxyl, hydroxyl, alkoxy, sulfonic acid group, and trimethoxysilyl. The groups mentioned above include not only the functional groups themselves, but also extended groups containing functional groups, such as cyano groups including -CN, -CH2-CN, etc., and carboxyl groups including -COOH, -CH2-CH2-COOH, etc. This configuration facilitates the precise tunability of the HOMO energy level in the range of -5.3 to -5.6 eV in hole transport materials through the electronic effects of peripheral functional groups, reducing the defect state density to 10. 14 cm -2 The following method ensures that the HTM film remains intact after immersion in a polar solvent for 24 hours.

[0079] In one embodiment, R1 in this invention is selected from one or more combinations of -H, -CH3, -Cl, -OCH3, -OC2H5, C1-C10 alkyl, -COOH, and -Si(OCH3)3; R2 is selected from one or more combinations of -C6H5, -OCH3, -OC2H5, C1-C10 alkyl, -COOH, and -Si(OCH3)3; R3 is selected from one or more combinations of -OCH3, -OC2H5, -CH2COOH, C1-C10 alkyl, -COOH, and -Si(OCH3)3; R4 is selected from -CN, -NH2, ... -F, -Cl, -Br, -I, C1-C10 alkyl, -COOH, -Si(OCH3)3; R5, R6, R7 are selected from one or more combinations of -F, -Cl, -Br, -I, C1-C10 alkyl, -SO3H, -COOH, -Si(OCH3)3, -CN, -NH2, -OCH3, -OC2H5, -C6H5, -H, -CH3, -Cl; R8 is selected from one or more combinations of -F, -Cl, -Br, -I, C1-C10 alkyl, -SO3H, -COOH, -Si(OCH3)3, -CN, -NH 2、 -OCH3, -OC2H5, -C6H5, -H, -CH3, -Cl, -CH2COOH, or a combination of one or more of these. The C1-C10 alkyl groups mentioned above refer to straight-chain or branched alkyl groups with 1-10 carbon atoms, preferably C1-C4 alkyl groups, i.e., -C n H2n+1 , 1≤n≤4, then optimize -C n H 2n+11 ≤ n ≤ 2. Introducing a methoxy group (-OCH3) at any position from R1 to R8 allows the methoxy group to combine with the host structure, achieving an electron-donating effect and simultaneously inducing an iodine ion effect in the perovskite material. This increases the electron cloud density in the molecule, raises the HOMO energy level, and passivates iodine defects. Furthermore, the combination of the methoxy group with the host structure reduces the interaction forces between the molecular chains of the hole transport material, increasing the material's flexibility. In addition, the combination of the methoxy group with the host structure improves the chemical stability of the hole transport material, reducing its degradation in the environment. The host structure mentioned above refers to the core skeleton in the overall structural formula, i.e., the structure in which no substituents are present at positions R1-R8. By placing a cyano group (-CN) at any of the R4-R8 positions, the cyano group, after combining with the host structure, generates inductive and conjugation effects due to electron-withdrawing behavior. As a hole transport material, it can effectively regulate the HOMO and LUMO energy levels of the molecule, lowering the HOMO energy level of the molecule and matching the HOMO energy level of the material with that of the perovskite layer. This promotes efficient hole injection from the perovskite layer to the hole transport layer, reduces charge recombination, and improves the photoelectric conversion efficiency of the device. By placing at least one methoxy group and one cyano group at the R1-R8 positions, the simultaneous presence of methoxy and cyano groups on the host structure allows them to work together to regulate the electronic structure distribution and molecular packing of the host structure, improving hole transport efficiency. Furthermore, the methoxy group enhances the chemical stability of the host structure material, reducing degradation, while the cyano group improves the physical stability of the material during film formation through intermolecular interactions. Together, these two factors enhance the long-term stability and lifespan of the hole transport material in photovoltaic devices. Halogen groups can be introduced at positions R1-R8, preferably at position R4. The halogen group at this position achieves conformational locking with the thiophene ring in the main structure through spatial interaction, restricting the free rotation of the molecular skeleton, improving molecular planarity, and enhancing π-electron delocalization. Simultaneously, the introduction of -F, -Cl, -Br, or -I will induce electron-withdrawing effects, matching the energy levels of the hole transport material with the perovskite material, reducing charge recombination losses due to energy level differences, and improving photoelectric conversion performance. The preferred halogen ion introduced at position R4 is fluorine. After combining with the main structure, fluorine's strong electron-withdrawing properties can regulate the surface work function of the hole transport material and the substrate, improving wettability with the organic active layer, reducing interface defects, and ensuring efficient hole transport from the SAM layer to the active layer. Introducing amino groups (-NH2) at the R4-R8 positions enhances the interaction between the amino groups and the active groups of the substrate metal oxide through covalent and hydrogen bonds, thereby improving the stability and order of the SAM and facilitating efficient hole transport. Its electron-donating ability can transfer lone pairs of electrons through redox reactions, enabling hole relay transport, reducing the potential barrier and increasing the migration rate.When the amino group is positioned at the R4 position, it can promote the ordered self-assembly of hole transport materials through intermolecular interactions such as hydrogen bonding. This ordered arrangement facilitates the formation of continuous hole transport channels, reduces scattering and trapping during hole transport, improves hole transport efficiency, and enhances the uniformity of the material's optical and electrical properties. Preferably, the main structure contains at least one amino group and one cyano group. The amino group can form strong hydrogen bonds with halide ions on the perovskite surface, effectively passivating halogen vacancy defects; the cyano group reacts with Pb. 2+ Coordination and passivation of lead ion-related defects. Together, these factors significantly reduce non-radiative recombination centers. Simultaneously, the amino and cyano groups finely modulate the electronic structure of the hole transport material, optimizing hole transport performance.

[0080] Introducing carboxyl groups (-COOH) or trimethoxysilane groups (-Si(OCH3)3) at any of the R1-R8 positions in the main structure provides stable attachment sites for the main structure, allowing auxiliary materials to be laterally and orderly stacked on the substrate surface, forming a dense and regular monolayer structure. Furthermore, the carboxyl groups can interact with the hydroxyl groups on the perovskite layer surface, forming more stable contacts at the interface and reducing interfacial recombination. The trimethoxysilane group undergoes a condensation reaction with the -OH group of the substrate metal oxide to form -Si-OH, which is covalently bonded through Si-OM bonds. The network structure formed by intermolecular crosslinking enhances the high-temperature resistance and mechanical exfoliation resistance of the hole transport material. Setting sulfonic acid groups (-SO3H) at any of the R5-R8 positions allows the structural molecules to form a hydrogen bond network with adjacent molecules or groups on the substrate surface. Its strong hydrophilicity significantly alters the surface wettability of the SAM material. The oxygen atom in the sulfonic acid group can react with Pb in the perovskite. 2+ Defects such as these form coordinate bonds.

[0081] Preferred embodiments include: R1 being one of hydrogen, aromatic group, methyl group, or chlorine atom; R2 being one of hydrogen, methyl group, or chlorine atom; R3 being one of hydrogen, chlorine atom, or carboxyl group; R4 being one of hydrogen, cyano group, fluorine atom, amino group, iodine atom, or chlorine atom; R5 being one of hydrogen, methoxy group, cyano group, or chlorine atom; R6 being one of hydrogen, cyano group, chlorine atom, or methoxy group; R7 being one of hydrogen and chlorine atom; and R8 being one of hydrogen, carboxyl group, chlorine atom, sulfonic acid group, or trimethoxysilyl group. Examples of implementable structural formulas 1-15 are as follows:

[0082] , , , , , , , , , , , , , , Preferred structural formulas include:

[0083] , , .

[0084] The preparation method of the tricyclic condensed and hole transport material in this invention will be introduced below using three materials as examples. Those skilled in the art can obtain the synthesis methods of the other materials based on this.

[0085] Material 1: The synthesis method is as follows:

[0086] .

[0087] The specific synthetic route can be divided into the following steps:

[0088] 1. Using a compound containing an amino group and a thiophene ring as a raw material, the compound (1) is reacted with 1,3-propanediol (HOCH2-CH2-CH2OH) at 50 °C under the action of p-nitrophenol (PhNO2) and sulfuric acid (H2SO4) to generate a compound (1).

[0089] 2. Compound (1) was reacted with liquid bromine (Br2) in ethanol (EtOH) to give compound (2).

[0090] 3. Compound (2) and pinacol ester of 2-fluorophenylboronic acid were reacted in toluene at 120 °C for 12 h under the catalysis of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) and tritert-butylphosphine (P(t-Bu)3) to give compound (3).

[0091] 4. Compound (3) was reacted at 65 °C for 12 h with tetrabutylammonium bromide (TBAB) and potassium hydroxide (KOH), and then reacted with bromobutane to obtain compound (4).

[0092] 5. Compound (4) was first reacted with triethyl phosphite at 165 °C for 24 h, then reacted with sodium triisobutylborohydride (SiBr(CH3)3) in dioxane at 25 °C for 20 h, and finally reacted at room temperature (RT) for 12 h in a mixed solution of methanol (MeOH) and water (H2O) to finally obtain the target product material 1.

[0093] The compounds (1), (2), (3), and (4) mentioned in the above steps correspond to (1), (2), (3), and (4) in the synthetic reaction formula. Material 1 modulates the molecular electron cloud distribution by introducing fluorine atoms onto the benzene ring, allowing the phosphate group -PO3H2 to interact with the perovskite surface metal sites (Pb). 2+ The more precise coordination and dual anchoring enhance the bonding force between the HTM and perovskite interfaces, efficiently passivating interface defects, accelerating hole transfer from the perovskite to the hole transport layer, improving charge extraction efficiency, and reducing recombination loss. Fluorine atoms enhance molecular hydrophobicity and, combined with the anchoring of phosphate groups, inhibit the intrusion of water vapor and oxygen into the perovskite layer, delaying material degradation. In the hole transport layer, the dipole-dipole interaction between molecules due to fluorine atoms makes the film more compact and ordered, reducing pinholes / grain boundaries, maintaining hole transport performance under long-term light and thermal cycling, and extending device life.

[0094] Material 2: The synthesis method is as follows:

[0095] ;

[0096] The specific synthetic route can be divided into the following steps:

[0097] 1. Using a starting material containing an amino group and a thiophene ring as raw material, the compound (1) is generated by reacting with 1,3-propanediol (HOCH2CH2CH2OH) under the action of p-nitrophenol (PhNO2) and sulfuric acid (H2SO4) through cyclization and other processes.

[0098] 2. Compound (1) was brominated by reacting with bromine (Br2) in ethanol (EtOH) solvent at 0 °C to give compound (2).

[0099] 3. Compound (2) and bis-pinacol boronic acid ester were reacted in toluene solvent at 120 °C for 12 h under the catalysis of tetra(triphenylphosphine)palladium (Pd(PPh3)4) and tritert-butylphosphine (P(t-Bu)3) to generate compound (3).

[0100] 4. Compound (3) and aromatic ring compounds containing bromine, iodine and bromoalkyl were reacted with palladium acetate (Pd(OAc)2), ligand SPhos and potassium phosphate (K3PO4) in dioxane / water (volume ratio 4:1) at 90 °C for 5 h to generate compound (4) via Suzuki coupling reaction.

[0101] 5. Compound (4) reacted with bromobutane at 65 °C for 12 h under the action of tetrabutylammonium bromide (TBAB) and potassium hydroxide (KOH) to undergo alkylation and further cyclization to obtain compound (5).

[0102] 6. Compound (5) was first reacted with triethyl phosphite at 165 °C for 24 h; then reacted with sodium triisobutylborohydride (SiBr(CH3)3) in dioxane solvent at 25 °C for 20 h; finally reacted with a mixed solution of methanol (MeOH) and water (H2O) at room temperature (RT) for 12 h. After reduction, hydrolysis and other processes, the target product material 2 was finally obtained.

[0103] The material 2 obtained by this method introduces phosphate groups -PO3H2, and the two phosphate groups interact with the perovskite surface metal sites (Pb). 2+ The iodine atom on the benzene ring forms stable coordination bonds, anchoring the phosphate group firmly to the perovskite layer like a "grip," resulting in stronger interfacial bonding than a single-anchored structure. The electron-withdrawing property of the iodine atom on the benzene ring regulates the electron distribution of the molecule, allowing for more precise anchoring of the phosphate group, efficiently passivating perovskite surface defects, reducing charge recombination, accelerating hole transfer from the perovskite to the transport layer, and improving charge extraction efficiency. The iodine atom alters the electron cloud density of the conjugated molecular system, fine-tuning the HOMO energy level of the hole transport material to match the perovskite valence band energy level, promoting hole injection and lowering the transport barrier. The conjugated system composed of sulfur heterocycles, nitrogen-containing heterocycles, and benzene rings provides a delocalized transport channel for holes. After anchoring with bisphosphate groups, the molecules are arranged in an orderly manner on the perovskite surface, facilitating "jumping" conduction of holes between molecules. Simultaneously, the interaction between the iodine atom and the heterocycle within the molecule makes the hole transport layer film more stable, maintaining hole transport performance under long-term light and thermal cycling, and extending device lifetime.

[0104] Material 3: The synthesis method is as follows:

[0105] .

[0106] The specific synthetic route can be divided into the following steps:

[0107] 1. Using a starting material containing an amino group and a thiophene ring as raw material, the compound (1) is generated by reacting 1,3-propanediol (HOCH2CH2CH2OH) with p-nitrophenol (PhNO2) and sulfuric acid (H2SO4) through cyclization and other processes.

[0108] 2. Compound (1) reacts with bromine (Br2) in ethanol (EtOH) solvent at 0 °C to undergo bromination, yielding compound (2).

[0109] 3. Compound (2) and bis-pinacol boronic acid ester were reacted in toluene solvent at 120 °C for 12 h under the catalysis of tetra(triphenylphosphine)palladium (Pd(PPh3)4) and tri-tert-butylphosphine (P(t-Bu)3) to undergo boronic acid esterification reaction to generate compound (3).

[0110] 4. Compound (3) and 4-bromo-3-aminobenzonitrile were reacted at 120 °C for 12 h under the conditions of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) and tritert-butylphosphine (P(t-Bu)3) as catalysts, sodium tert-butoxide (BuONa) as base, and toluene as solvent, to generate compound (4) via Suzuki coupling reaction.

[0111] 5. Compound (4) reacted with bromobutane at 65°C for 12 h in the presence of tetrabutylammonium bromide (TBAB) and potassium hydroxide (KOH) to undergo alkylation and further cyclization, yielding compound (5).

[0112] 6. Compound (5) was first reacted with triethyl phosphite at 165 °C for 24 h; then reacted with sodium triisobutylborohydride (SiBr(CH3)3) in dioxane solvent at 25 °C for 20 h; finally reacted with a mixed solution of methanol (MeOH) and water (H2O) at room temperature (RT) for 12 h. After reduction, hydrolysis and other processes, the target product material 3 was finally obtained.

[0113] Material 3 obtained by this method can interact with metal sites on the perovskite surface (such as Pb) via the phosphate group -PO3H2. 2+ The formation of coordination bonds enhances the interfacial bonding between HTM and perovskite. The cyano and amino groups on the benzene ring exhibit an electron-withdrawing and electron-pushing "push-pull" effect, regulating the molecular electron cloud distribution. This allows for more precise anchoring of the phosphate group, efficiently passivating perovskite surface defects, reducing charge recombination, and accelerating hole transfer from perovskite to HTM. Together, these heterocyclic frameworks fine-tune the HOMO energy level of HTM. The sulfur heterocycle, nitrogen-containing heterocycle, and benzene ring form a large conjugated system, providing a delocalized transport path for holes. After anchoring with the phosphate group, the molecules are arranged in an ordered manner on the perovskite surface, facilitating "jumping" hole transport between molecules. The rigid planar structure of the benzene ring further enhances the conjugated transport efficiency. The intramolecular cyano-amino group electronic interaction and the steric hindrance of the heterocycle and benzene ring ensure that the HTM film maintains an ordered structure over a long period, resulting in stable hole transport performance.

[0114] Perovskite photovoltaic devices can be fabricated using the tricyclic fused hole transport material of this invention. These devices can be single-junction, tandem, conventional, or inverted perovskite cells. The perovskite photovoltaic device of this invention comprises a conductive substrate, a hole transport layer, a perovskite layer, and an electron transport layer. Preferably, the above thin film layers are arranged sequentially, i.e., the perovskite has an inverted structure. More preferably, the perovskite material in the perovskite layer is ABX3, where A represents formamidinium ions, methylamine ions, and Cs. +One or more combinations of B, where B is lead ion, and C is one or a combination of iodide ion and bromide ion, are used. This configuration facilitates energy level matching and defect passivation efficiency between the hole transport material and the perovskite material. A further preferred configuration is as follows: a modification layer is disposed between the perovskite layer and the electron transport layer. The modification layer material is ethylenediamine dihydroiodide, and the precursor materials of the perovskite material are lead iodide, formamidinium hydroiodate, lead bromide, and formamidinium hydrobromide. The electron transport layer is a combination of C60 and SnO2, with the C60 disposed close to the modification layer. The structural formula of the hole transport layer material is as follows:

[0115] .

[0116] The fabrication method of the perovskite photovoltaic device in this invention includes the following steps:

[0117] S01 Obtain the substrate;

[0118] S02. A hole transport layer is prepared. The hole transport layer material is the aforementioned tricyclic fused hole transport material, preferably prepared by a solution method. The tricyclic fused hole transport material is dissolved in an organic solvent to obtain a hole transport layer precursor solution. The hole transport layer precursor solution is coated on the side of the substrate where the metal oxide is disposed, and then annealed to form a film. The concentration of the tricyclic fused hole transport material in the hole transport layer precursor solution is 0.5~1.5 mg / mL. At this concentration, it is beneficial to the uniform film formation of the hole transport layer itself, and on this basis, it guides the uniform film formation of the perovskite layer.

[0119] SO3 is used to prepare a perovskite layer;

[0120] SiO4 is used to prepare an electron transport layer;

[0121] S05 Prepare the electrode layer.

[0122] The fabrication method of a single-junction inverted perovskite photovoltaic device is illustrated using this example:

[0123] (1) Obtaining the substrate: using ITO or FTO glass as the substrate;

[0124] (2) Preparation of hole transport layer: Prepare hole transport layer precursor solution, coat the hole transport layer precursor solution on the side of the substrate where ITO or FTO is provided, and anneal to form a film.

[0125] (3) Preparation of perovskite layer: Perovskite precursor material is dissolved in organic solvent to prepare perovskite precursor solution; the perovskite precursor solution is coated on hole transport layer and annealed to form film; in addition, perovskite layer can also be prepared by vapor deposition or spraying perovskite precursor material.

[0126] (4) Preparation of modification layer: Prepare modification layer solution and coat it on perovskite layer. Preferably, the modification layer solution is an isopropanol solution of ethylenediamine dihydroiodide.

[0127] (5) Preparation of electron transport layer: deposit electron transport layer material on perovskite layer, preferably a combination of C60 and SnO2, wherein C60 is disposed close to the modification layer;

[0128] (6) Preparation of metal electrodes: Electrode layer Ag layer is prepared on electron transport layer using vacuum evaporation equipment.

[0129] The following is a more detailed description using specific embodiments.

[0130] Example 1

[0131] The tricyclic condensed hole transport material is material 1, and its structural formula is:

[0132] .

[0133] The preparation method of material 1 is as follows:

[0134] 1. The amino / thiophene compound was condensed with 1,3-propanediol to give compound (1).

[0135] In a 250 mL three-necked flask, 15.72 g of methyl 2-aminothiophene-3-carboxylic acid, 21.0 mL of 1,3-propanediol, and 1.39 g of p-nitrophenol were added sequentially, and the mixture was stirred until the solids were completely dissolved to form a reaction system.

[0136] The reaction system was cooled to below 10 °C using an ice bath, and 0.27 mL of 98% sulfuric acid was slowly added dropwise, with the temperature controlled to ≤15 °C during the addition. After the addition was complete, the ice bath was removed, and the reaction system was heated to 50 °C and reacted at a constant temperature in an oil bath for 8 hours.

[0137] After the reaction was completed, the system was cooled to room temperature and slowly poured into 100 mL of ice water. The pH was adjusted to 6-7 with saturated NaHCO3 solution. The mixture was extracted with ethyl acetate, and the organic phases were combined. The mixture was washed with saturated NaCl solution, dried overnight with anhydrous Na2SO4, filtered to remove the drying agent, and concentrated to dryness by rotary evaporation to obtain a pale yellow oily compound (1).

[0138] Yield: 18.2 g; Yield: 85%; Purity: ≥95%.

[0139] 2. Compound (1) is brominated to obtain compound (2).

[0140] In a 250 mL three-necked flask, add 18.2 g of compound (1) and anhydrous ethanol, stir until completely dissolved, cool to 0 °C in an ice bath and maintain constant temperature. Slowly add 4.8 mL of liquid bromine using a constant pressure dropping funnel, controlling the addition time at 30 min. During the addition process, a pale yellow solid gradually precipitates from the system.

[0141] After the addition was complete, the reaction was continued at 0 °C for 2 h. After the reaction was completed, 100 mL of saturated Na2SO3 solution was slowly added dropwise until the color of the system changed from orange-red to colorless, at which point a large amount of solid precipitated. The solid was collected by suction filtration, washed with ice water until the filtrate was neutral, then rinsed with a small amount of cold ethanol, and dried under vacuum to obtain a pale yellow powder compound (2). Yield: 21.5 g; Yield: 90%; Purity: ≥98%; Structure verification: ¹H NMR (DMSO-d6, 400 MHz): δ 8.21 (s, 1H, thiophene 5-H, disappeared after Br substitution, verifying successful bromination).

[0142] 3. Compound (2) was converted into compound (3) by a Suzuki coupling reaction.

[0143] In a 500 mL two-necked flask, 21.5 g of compound (2), 21.8 g of pinacol 2-fluorophenylboronic acid, 4.4 g of Pd(PPh3)4, and 4.6 mL of 10% P(t-Bu)3 toluene solution were added sequentially. The air in the flask was replaced three times with nitrogen. 200 mL of anhydrous toluene was added, and the mixture was stirred to disperse the solid. Then, 100 mL of pre-dissolved K2CO3 aqueous solution (31.8 g) was added to form a two-phase system. A reflux condenser was attached, and the temperature was raised to 120 °C under nitrogen protection and the reaction was maintained at this temperature for 12 h. After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, and the organic phase was collected. The aqueous phase was extracted with toluene, and the organic phases were combined. The organic phase was washed with saturated NaCl solution, dried overnight with anhydrous MgSO4, and after filtration, purification, and concentration, a pale yellow solid compound (3) was obtained.

[0144] Yield: 22.3 g;

[0145] Yield: 82%;

[0146] Purity: ≥97%;

[0147] Structural verification:¹ 9 FNMR (CDCl3, 376 MHz): δ-112.5 (s, 1H, F atom of 2-fluorophenyl, confirming successful coupling).

[0148] 4. Compound (3) was alkylated to obtain compound (4).

[0149] In a 250 mL three-necked flask, add 22.3 g of compound (4), 2.0 g of TBAB, and 150 mL of anhydrous toluene, and stir to disperse. In a separate beaker, dissolve 10.5 g of KOH in 50 mL of deionized water, cool to room temperature, and pour into the flask to form a biphase system.

[0150] The biphase system was heated to 65 °C and stirred for 30 min to fully convert -OH to -O⁻. Then, 10.8 mL of bromobutane was slowly added dropwise. After the addition was complete, the reaction was continued at 65 °C for 12 h.

[0151] After the reaction was completed, the mixture was cooled to room temperature, allowed to stand and separate into layers, the organic phase was collected, the aqueous phase was extracted with toluene, and the organic phases were combined. The organic phase was washed successively with deionized water and saturated NaCl solution, and dried overnight with anhydrous Na2SO4. After filtration and purification, a colorless oily compound (5) was obtained.

[0152] Yield: 22.9 g; Yield: 88%; Purity: ≥96%.

[0153] 5. Compound (5) was used to obtain the target product material 1 through reduction and hydrolysis reactions.

[0154] In a 250 mL three-necked flask, 22.9 g of compound (5) and 1.6 g of triethyl phosphite were added, and the temperature was raised to 165 °C and reacted at this temperature for 24 h. After cooling to room temperature, 120 mL of anhydrous 1,4-dioxane was added, and the mixture was stirred until dissolved. The air in the flask was replaced with nitrogen three times, and the temperature was lowered to 0 °C in an ice bath. 22.5 g of NaBH(i-Bu)3 was slowly added dropwise. After the addition was complete, the temperature was raised to 25 °C and reacted at this temperature for 20 h.

[0155] After the reaction was complete, the mixture was cooled to 0 °C in an ice bath, and 80 mL of methanol was slowly added dropwise to quench the excess reducing agent. Then, 20 mL of deionized water was added, and the mixture was stirred at room temperature for 12 h to hydrolyze the residual protecting group. The pH was adjusted to 5-6 with 1 mol / L hydrochloric acid, and the mixture was concentrated by rotary evaporation to approximately 50 mL. 100 mL of deionized water was added, and the mixture was extracted with ethyl acetate. The combined organic phases were washed with saturated NaCl solution, dried overnight in anhydrous MgSO4, filtered, and concentrated to dryness. The mixture was then recrystallized and purified, and dried under vacuum for 6 h to obtain white crystalline material 1.

[0156] Yield: 18.1 g; Total yield: 68%; Purity: ≥99%.

[0157] The final product was analyzed using hydrogen nuclear magnetic resonance and Fourier transform infrared spectroscopy. The analytical results are as follows: Figure 1 and Figure 4 As shown, the obtained product is the target product material 1.

[0158] Example 2

[0159] The tricyclic condensed hole transport material is material 2, and the preparation method of material 2 is as follows:

[0160] .

[0161] The final product was analyzed using hydrogen nuclear magnetic resonance and Fourier transform infrared spectroscopy. The analytical results are as follows: Figure 2 and Figure 4 Therefore, the obtained product is the target product material 2.

[0162] Example 3

[0163] The tricyclic condensed hole transport material is material 3, and the preparation method of material 3 is as follows:

[0164] .

[0165] The final product was analyzed using hydrogen nuclear magnetic resonance and Fourier transform infrared spectroscopy. The analytical results are as follows: Figure 3 and Figure 4 It can be seen that the obtained product is the target product material 3.

[0166] Example 4

[0167] A pin-type wide-bandgap perovskite (1.67 eV) solar cell was fabricated using material 1 obtained in Example 1 as the hole transport material. The fabrication method of the perovskite solar cell is as follows:

[0168] S01 Obtaining the substrate—ITO glass

[0169] The ITO glass substrate was sequentially sonicated in deionized water, ethanol, and isopropanol for 30 minutes each, dried with a nitrogen gun, and then treated in an ultraviolet ozone processor for 15 minutes before use.

[0170] S02 is used to prepare the hole transport layer.

[0171] A 1 mg / mL solution of Material 1 was accurately prepared. 3-(2-fluorophenyl)-5,6-dihydro-4H-cyclopentano[4,5]thieno[2,3-b]pyrrolo-1-yl]butylphosphonic acid was dissolved in ethanol and stirred for 12 h. The solution was then filtered through an organic membrane with a pore size of 0.22 μm. The Material 1 solution was spin-coated onto ITO glass at 4000 rpm for 40 s, followed by annealing at 120 °C for 10 min to obtain the hole transport layer.

[0172] Preparation of S03 perovskite layer

[0173] a. Prepare a 1.7 M perovskite precursor solution

[0174] The perovskite precursor solution consisted of lead iodide (PbI2), formamidinium hydroiodate (FAI), lead bromide (PbBr2), and formamidinium hydrobromide (FABr) in a molar ratio of 0.75:0.75:0.25:0.25. The solvent used was N,N-dimethylformamide (DMF):dimethyl sulfoxide (DMSO) at a ratio of 4:1. After thorough stirring and dissolution, the solution was filtered through an organic filter membrane with a pore size of 0.22 μm.

[0175] b. The perovskite precursor solution was spin-coated onto the hole transport layer in a two-step process by adding 100 μL of the antisolvent chlorobenzene (CB) at 1000 rpm for 10 s and 3000 rpm for 30 s, and then adding 100 μL of the antisolvent chlorobenzene (CB) dropwise at the last 10 s. The perovskite layer was then annealed at 100 °C for 10 min.

[0176] Preparation of S04 Modified Layer

[0177] a. Obtain the modified layer solution: 0.5 mg / mL of ethylenediamine dihydroiodide (EDAI2) in isopropanol;

[0178] b. Film formation: The modification layer solution was spin-coated onto the perovskite layer at 3000 rpm for 30 s, and then annealed at 100 ℃ for 10 min to form the perovskite modification layer.

[0179] Fabrication of S05 electron transport layer

[0180] 10 nm of C60 was sequentially vacuum-deposited on the perovskite layer, followed by 15 nm of SnO2 deposition via ALD.

[0181] Preparation of S06 electrode

[0182] Using a vacuum evaporation apparatus, 10 nm of Ag was evaporated at a rate of 0.2 Å / s on the electron transport layer, followed by 180 nm of Ag at a rate of 2 Å / s.

[0183] Example 5

[0184] Perovskite solar cells were fabricated using material 2 obtained in Example 2 as the hole transport material. This example is an inverted 1.54 eV bandgap FAPbI3 perovskite solar cell, and the fabrication method includes the following steps:

[0185] S01 Obtaining the substrate—FTO glass

[0186] FTO glass was used as the substrate. The FTO glass substrate was first ultrasonically cleaned in detergent and deionized water for 20 minutes each, then ultrasonically cleaned in acetone for 20 minutes, and finally ultrasonically cleaned in IPA for 20 minutes. After that, it was dried with a nitrogen gun and placed in a UV ozone processor for 15 minutes for later use.

[0187] S02 is used to prepare the hole transport layer.

[0188] (1) Dissolve 0.5 mg of material 2: compound 3-(2-iodophenyl)-N-(4-phosphonobutyl)-5,6-dihydro-4H-cyclopentano[4,5]thieno[2,3-b]pyrrolo-1-yl]butylphosphonic acid in 1 mL of ethanol to obtain a hole transport layer precursor solution of 0.5 mg / mL. Filter the solution with a 0.45 μm filter to remove large particles. The filtered solution is used for later use.

[0189] (2) Spin-coat the filtered solution onto the side of the FTO glass containing FTO at a spin rate of 3500 rpm for 30 s.

[0190] (3) Anneal at 120 °C for 10 min to obtain a hole transport layer with a thickness of about 3 nm.

[0191] Preparation of S03 perovskite layer

[0192] (1) Preparation of FAI+PbI2 solution: 691.5 mg of PbI2 and 258 mg of FAI were dissolved in 890 μL of DMF and 110 μL of DMSO. The solution was stirred at room temperature for 2 h until completely dissolved. The solution was filtered with a 0.45 μm filter to remove larger particles and obtain a 1.5 M perovskite precursor solution.

[0193] (2) The prepared perovskite precursor solution was spin-coated at a speed of 5000 rpm for 60 s. At the 10th s of spin coating, 150 μL of the antisolvent ethyl acetate was uniformly added to the film. Then, the film was annealed at 150 °C for 15 min under a nitrogen atmosphere. After cooling, the film was set aside to form a perovskite layer with a thickness of 500 nm.

[0194] Preparation of S04 Modified Layer

[0195] (1) Preparation of EDAI2 surface modification layer solution: Dissolve 0.5 mg of EDAI2 in 1 mL of isopropanol, shake and stir to form a 0.5 mg / mL surface modification layer EDAI2 solution, and filter it with a 0.45 μm filter to remove larger particles in the solution.

[0196] (2) Spin-coat the EDAI2 solution onto the perovskite layer at a speed of 5000 rpm for 30 s, and then anneal it in a glove box at 100 ℃ for 5 min to form a modified layer with a thickness of about 3 nm.

[0197] Fabrication of S05 electron transport layer

[0198] 10 nm of C60 was sequentially vacuum-deposited on the perovskite layer, followed by 15 nm of SnO2 deposition via ALD.

[0199] Preparation of S06 electrode

[0200] A 100 nm Ag layer was deposited on the surface of the hole blocking layer using thermal evaporation as an electrode.

[0201] Example 6

[0202] Perovskite solar cells were fabricated using material 3 obtained in Example 3 as the hole transport layer material. This example is an inverse CsPbI3 perovskite solar cell with a bandgap of 1.73 eV. The fabrication method includes the following steps:

[0203] S01 Obtain the substrate

[0204] FTO glass was used as the substrate. The FTO glass substrate was first ultrasonically cleaned in detergent and deionized water for 20 minutes each, then ultrasonically cleaned in acetone for 20 minutes, and finally ultrasonically cleaned in IPA for 20 minutes. After that, it was dried with a nitrogen gun and placed in a UV ozone processor for 15 minutes for later use.

[0205] S02 is used to prepare the hole transport layer.

[0206] (1) Mix 1.5 mg of material 3: 3-(2-amino-4-cyanophenyl)-N-(4-phosphonobutyl)-5,6-dihydro-4H-cyclopentano[4,5]thieno[2,3-b]pyrrole with 1 mL of ethanol solution to obtain a solution of 1.5 mg / mL. Filter the solution with a 0.45 μm filter to remove large particles. The filtered solution is ready for use.

[0207] (2) Spin-coat the filtered solution onto the side of the FTO glass containing FTO at a spin rate of 3000 rpm for 30 s.

[0208] (3) Anneal at 120 °C for 10 min to obtain a hole transport layer with a thickness of about 3 nm.

[0209] Preparation of S03 perovskite layer

[0210] (1) Preparation of CsPbI3 solution: 322.7 mg of PbI2 and 181.3 mg of CsI were dissolved in 850 μL of DMF and 150 μL of DMSO. The solution was stirred at room temperature for 2 h until completely dissolved. The solution was filtered with a 0.45 μm filter to remove larger particles, and a perovskite precursor solution with a concentration of 0.7 M was obtained.

[0211] (2) The prepared solution was spin-coated at a speed of 3500 rpm for 40 s. Then it was annealed at 70 °C for 2 min under a nitrogen atmosphere, followed by annealing at 170 °C for 50 min in an air environment with 10% humidity. After cooling, it was set aside to form a perovskite layer with a thickness of 600 nm.

[0212] Preparation of S04 Modified Layer

[0213] (1) Preparation of EDAI2 surface modification layer solution: Dissolve 0.5 mg of EDAI2 in 1 mL of isopropanol, shake and stir to form a 0.5 mg / mL surface modification layer EDAI2 solution, and filter it with a 0.45 μm filter to remove larger particles in the solution.

[0214] (2) Spin-coating the EDAI2 solution onto the perovskite layer at a speed of 5000 rpm for 30 s, followed by annealing in a glove box at 100 ℃ for 5 min to form a modified layer with a thickness of about 3 nm.

[0215] Preparation of S05 electron transport layer

[0216] 10 nm of C60 was sequentially vacuum-deposited on the perovskite layer, followed by 15 nm of SnO2 deposition via ALD.

[0217] Preparation of S06 electrode

[0218] A 100 nm Ag layer was deposited on the surface of the hole blocking layer using thermal evaporation as an electrode.

[0219] Comparative Example 1

[0220] Perovskite solar cells were prepared using existing materials as hole transport materials. The only difference between the preparation method of the perovskite solar cells and that of Example 4 is that the hole transport layer material used is MeO-2PACz ((2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid). 1 mg of MeO-2PACz was mixed with 1 mL of ethanol solution to obtain a 1 mg / mL MeO-2PACz solution. Large particles were removed by filtration using a 0.45 μm filter element. After filtration, the hole transport layer precursor solution was obtained.

[0221] The photoelectric conversion efficiency of the perovskite photovoltaic devices of Example 4 and Comparative Example 1 is shown in Table 1 and Figure 5 As shown, the conversion efficiency of the perovskite photovoltaic device in Example 4 is significantly improved compared to Comparative Example 1, indicating that this material has a high hole mobility, which can reduce the energy loss during the migration of holes from the perovskite layer to the hole transport layer, and is beneficial to improving the open-circuit voltage of the device. From Figure 6 (a) Figure 6(b) SEM results show that its good film-forming properties fill the tiny defects and pinholes on the surface of the perovskite layer and improve the surface smoothness of the film.

[0222] Table 1. Parameters of device efficiency based on Example 4 and Comparative Example 1

[0223] Voltage (V) Photoelectric conversion efficiency (%) filling(%) <![CDATA[Current density (mA / cm 2 )]]> Example 4 1.24 22.64 84.69 21.46 Comparative Example 1 1.23 22.16 82.87 21.52

[0224] Comparative Example 2

[0225] The only difference between the perovskite optical device fabrication method in this comparative example and that in Example 5 is the hole transport material. The hole transport layer material used in this comparative example S02 is MeO-2PACz. 1 mg of MeO-2PACz is mixed with 1 mL of ethanol solution to obtain a 1 mg / mL MeO-2PACz solution. Large particles are removed by filtration using a 0.45 μm filter core. After filtration, a hole transport layer precursor solution is obtained.

[0226] The photoelectric conversion efficiency of the perovskite photovoltaic devices of Example 5 and Comparative Example 2 is shown in Table 2 and... Figure 7 As shown, the conversion efficiency of the perovskite solar cell in Example 5 is significantly improved compared to Comparative Example 2, indicating that this material has a high hole mobility, which can reduce the energy loss during the migration of holes from the perovskite layer to the hole transport layer, and is beneficial to improving the open-circuit voltage of the device. From Figure 8 (a) and Figure 8 (b) SEM results show that its good film-forming properties fill the small defects and pinholes on the surface of the perovskite layer, improve the surface smoothness of the film, and have a higher fill factor.

[0227] Table 2. Parameters of device efficiency based on Example 5 and Comparative Example 2

[0228] Voltage (V) Photoelectric conversion efficiency (%) filling(%) <![CDATA[Current density (mA / cm 2 )]]> Example 5 1.15 23.47 82.10 25.58 Comparative Example 2 1.13 24.20 81.09 25.53

[0229] Comparative Example 3

[0230] The only difference between the preparation method of the perovskite solar cell in this comparative example and that in Example 6 is the hole transport material. In this comparative example, the hole transport material used in SO2 is MeO-2PACz. 1 mg of MeO-2PACz is mixed with 1 mL of ethanol solution to obtain a 1 mg / mL MeO-2PACz solution. Large particles are removed by filtration using a 0.45 μm filter element. After filtration, a hole transport layer precursor solution is obtained.

[0231] The photoelectric conversion efficiency of the perovskite photovoltaic devices of Example 6 and Comparative Example 3 is shown in Table 3. Figure 9As shown, the conversion efficiency of the perovskite photovoltaic device in Example 6 is significantly improved compared to that in Comparative Example 3, indicating that this material can reduce energy loss during the migration of holes from the perovskite layer to the hole transport layer, which is beneficial to improving the open-circuit voltage of the device. From Figure 10 (a) and Figure 10 (b) SEM results show that its good film-forming properties fill the small defects and pinholes on the surface of the perovskite layer, improve the surface smoothness of the film, and have a higher fill factor.

[0232] Table 3. Parameter table of device efficiency based on Example 6 and Comparative Example 3.

[0233] Voltage (V) Photoelectric conversion efficiency (%) filling(%) <![CDATA[Current density (mA / cm 2 )]]> Example 6 1.25 21.23 82.50 20.57 Comparative Example 3 1.17 18.95 79.12 20.33

[0234] The present invention synthesized the compounds corresponding to the remaining structural formulas in Examples 1-15, and prepared a perovskite battery according to Example 4. The battery efficiency and perovskite crystal morphology of the prepared battery were better than those of the battery in Comparative Example 1.

[0235] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A tricyclic condensed hole transport material, characterized in that: The structural formula is ； In the formula: R1 and R2 are each independently selected from one or more combinations of hydrogen, C1-C10 alkyl, methoxy, ethoxy, phenyl, halogen group, carboxyl, and trimethoxysilyl; R3 is selected from one or more combinations of hydrogen, C1-C10 alkyl, methoxy, ethoxy, phenyl, halogen group, carboxyl, and trimethoxysilyl; R4 is selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen group, nitro, hydroxy, C1-C10 alkyl, sulfonic acid group, and trimethoxysilyl; R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen group, nitro, hydroxy, C1-C10 alkyl, sulfonic acid group, methoxy, ethoxy, and trimethoxysilyl.

2. The tricyclic fused hole transport material according to claim 1, characterized in that: R3 is selected from one or more combinations of hydrogen, C1-C10 alkyl, methoxy, ethoxy, halogen group, carboxyl, and trimethoxysilyl; R4 is selected from one or more combinations of hydrogen, cyano, carboxyl, amino, halogen group, C1-C10 alkyl, and trimethoxysilyl; R5, R6, R7, and R8 are each independently selected from one or more combinations of hydrogen, cyano, amino, nitro, carboxyl, hydroxyl, methoxy, ethoxy, sulfonic acid, trimethoxysilyl, and halogen groups.

3. The tricyclic fused hole transport material according to claim 1 or 2, characterized in that: R1 is one of hydrogen, phenyl, methyl, or chlorine atoms; R2 is one of hydrogen, methyl, or chlorine atoms; R3 is one of hydrogen, chlorine, or carboxyl groups; R4 is one of hydrogen, cyano, fluorine, amino, iodine, or chlorine atoms; R5 is one of hydrogen, methoxy, cyano, or chlorine atoms; R6 is one of hydrogen, cyano, chlorine, or methoxy groups; R7 is one of the hydrogen or chlorine atoms; R8 is one of hydrogen, carboxyl, chlorine, sulfonic acid, or trimethoxysilyl groups.

4. A tricyclic condensed hole transport material, characterized in that: The structural formula is: 、 、 、 、 、 、 、 、 、 、 、 、 、 。 5. The tricyclic condensed hole transport material according to claim 1 or 2, characterized in that: R1-R8 contain at least a cyano group and a methoxy group, or R1-R8 contain at least an amino group and a cyano group.

6. A perovskite photovoltaic device, characterized in that: It includes a conductive substrate, a hole transport layer, a perovskite layer, and an electron transport layer, wherein the hole transport layer uses the tricyclic fused hole transport material described in claim 1 as the hole transport material.

7. The photovoltaic device according to claim 6, characterized in that: The perovskite material in the perovskite layer is ABX3, where A represents formamidinium ion, methylamine ion, and Cs. + One or more of the following, where B is lead ion and C is one or a combination of two of iodide ions and bromide ions.

8. The photovoltaic device according to claim 6 or 7, characterized in that: A conductive substrate, a hole transport layer, a perovskite layer, and an electron transport layer are arranged sequentially. A modification layer is disposed between the perovskite layer and the electron transport layer. The modification layer material is ethylenediamine dihydroiodide. The precursor materials for the perovskite material are lead iodide, formamidinium hydroiodate, lead bromide, and formamidinium hydrobromide. The electron transport layer is a combination of C60 and SnO2, with the C60 disposed close to the modification layer. The structural formula of the hole transport layer material is as follows. 。 9. A method for fabricating the perovskite photovoltaic device according to claim 6, characterized in that: Includes the following steps: S01 Obtaining the substrate: A metal oxide is disposed on the side of the substrate facing the hole transport layer; S02 Preparation of hole transport layer: Prepare hole transport layer precursor solution and coat the hole transport layer precursor solution on the side of the substrate where the metal oxide is disposed; S03 Preparation of perovskite layer: Perovskite precursor material is dissolved in an organic solvent to prepare perovskite precursor solution; The perovskite precursor solution is coated onto the hole transport layer and then annealed to form a film, or it is prepared by vapor deposition or spraying of perovskite precursor material. S04 Preparation of Electron Transport Layer: Electron transport layer material is deposited on the perovskite layer; S05 Electrode layer preparation: Electrode layers are prepared on the electron transport layer using vacuum evaporation equipment; The hole transport layer is made of a tricyclic condensed material and a hole transport material, the structural formula of which is: 。 10. A preparation method according to claim 9, characterized in that: The substrate has a metal oxide disposed on the side facing the hole transport layer. The hole transport layer is prepared by a solution method, which involves dissolving a tricyclic fused hole transport material in an organic solvent to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution onto the side of the substrate with the metal oxide disposed, and annealing to form a film. The concentration of the tricyclic fused hole transport material in the hole transport layer precursor solution is 0.5~1.5 mg / mL.

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