Indolocarbazole-based hole transport material and preparation method and application thereof

Abstract

The invention relates to the technical field of photoelectric materials, and provides an indolocarbazole-based hole transport material and a preparation method and application thereof, and the indolocarbazole-based hole transport material is polyphosphoric acid indolocarbazole. The polyphosphoric acid indolocarbazole is used as a hole transport layer material in an organic solar cell or a perovskite solar cell; or the polyphosphoric acid indolocarbazole is used for interface modification on the basis of an original hole transport layer. The indolocarbazole-based hole transport material provided by the invention has the advantages of good stability, excellent hole transport performance, good passivation effect, solution processability, good wettability and coating uniformity, high photoelectric conversion efficiency and the like.

Description

Technical Field

[0001] The present application belongs to the technical field of optoelectronic materials, and in particular relates to an indolecarbazole-based hole transport material and a preparation method and application thereof. Background Art

[0002] PACz (Phosphoric Acid Carbazole) is a hole transport material developed in recent years. It has the advantage of being solution processable and can form a monolayer on a conductive substrate. Compared with polytriphenylamine-based hole transport layer materials, perovskite films have better wettability on phosphoric acid carbazole, which is conducive to large-area coating of perovskite films and the realization of efficient hole transport in inverse perovskite photovoltaics.

[0003] Nowadays, small molecule carbazole phosphate has become a commonly used hole transport material for trans-structured perovskite solar cells. Although small molecule carbazole phosphate has excellent hole transport performance, its own compactness and stability have always been a problem. Small molecule carbazole phosphate needs to form a dense and uniform monolayer on a conductive substrate to achieve efficient hole transport, but in the actual solution processing process, small molecules of carbazole phosphate will form multiple molecular layers locally, increasing the resistance to hole extraction. Small molecule carbazole phosphate will also diffuse into the perovskite active layer under photothermal conditions. In addition, on some rough conductive substrates, such as FTO (Fluorine-doped Tin Oxide, fluorine-doped tin oxide), small molecule carbazole phosphate cannot completely cover the entire conductive substrate, so that the perovskite film is in direct contact with the conductive substrate. This situation causes local leakage on the one hand, and on the other hand, the conductive substrate induces the decomposition of perovskite, causing the attenuation of the perovskite solar cell.

[0004] Therefore, developing new hole transport layer materials to solve the problems existing in the current small molecule carbazole phosphate is an important step to improve the stability of trans-perovskite photovoltaic devices and promote their industrialization. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a hole transport material based on indolecarbazole and its preparation method and application, aiming to solve the current problem that small molecule phosphate carbazole forms a multi-molecular layer locally on the conductive substrate, increases the resistance to hole extraction, and the poor stability of trans-perovskite photovoltaic devices.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, an embodiment of the present application provides a hole transport material based on indole and carbazole, selected from at least one of compound formula 1, formula 2, formula 3 and formula 4, wherein the structural formulas of the compounds of formula 1, formula 2, formula 3 and formula 4 are as follows:

[0008]

[0009] Wherein, n is 2-10000, and m is 1-100.

[0010] In some embodiments, the indolecarbazole-based hole transport material is indolecarbazole polyphosphate, wherein the indolecarbazole polyphosphate comprises at least one of the monomers of the following structural formulas:

[0011]

[0012] The value range of i is 1 to 40;

[0013] The Rx is independently selected from at least one of a hydrogen atom, a halogen group, a cyano group, an alkyl group, an aromatic group, and a cyclic group.

[0014] In a second aspect, the present application provides a method for preparing a hole transport material based on indolecarbazole, comprising the following steps:

[0015] Providing halogenated phosphate indole and carbazole, silanization reagent, alcohol and solvent;

[0016] dissolving the halogenated phosphate indolecarbazole in the solvent to carry out copolymerization reaction to obtain an intermediate reactant;

[0017] The silanization agent and the alcohol are added to the intermediate reactant for hydrolysis to obtain indolecarbazole polyphosphate, which is the indolecarbazole-based hole transport material.

[0018] In some embodiments, the reaction time of the copolymerization reaction is 0.1 h to 72 h.

[0019] In some embodiments, the reaction temperature of the copolymerization reaction is 50°C to 200°C.

[0020] In some embodiments, the alcohol includes at least one of methanol, ethanol, and propanol.

[0021] In some embodiments, the solvent includes one of dimethylformamide, toluene, chlorobenzene, xylene, and tetrahydrofuran.

[0022] In some embodiments, dissolving the halogenated phosphate indolecarbazole in the solvent for copolymerization to obtain the intermediate reactant comprises:

[0023] Under a nitrogen environment, 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and sodium hydride are dissolved in dimethylformamide, and then diethyl-4-bromobutylphosphonic acid is added to react. After the reaction is completed, extraction and concentration are performed, and the crude product is purified by column chromatography to obtain a first compound;

[0024] Dissolving nickel, bipyridine and 1,5-cyclooctadiene in dimethylformamide, and then heating and stirring to obtain a first solution;

[0025] The first compound is dissolved in dimethylformamide to obtain a second solution, and then the first solution is slowly added dropwise to the second solution, heated and stirred to react, and after the reaction is completed, cooled and filtered to obtain the intermediate reactant.

[0026] In some embodiments, the adding of the silanization agent and the alcohol to the intermediate reactant for hydrolysis to obtain indolecarbazole polyphosphate, wherein the indolecarbazole polyphosphate is the indolecarbazole-based hole transport material and comprises:

[0027] The intermediate reactant is dissolved in dichloromethane, and then trimethylsilyl bromide is added dropwise, and stirred at room temperature. After the reaction is completed, excess methanol is added dropwise, and then vacuum distillation is performed to concentrate, precipitate, filter, and rinse to obtain the indolecarbazole-based hole transport material.

[0028] In some embodiments, before dissolving 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and sodium hydride in dimethylformamide, the method further comprises:

[0029] Nitrogen is replaced several times to prevent sodium hydride from reacting with oxygen or moisture in the air, thereby ensuring the safety and purity of the reaction.

[0030] In some embodiments, the purity of the sodium hydride is 60% ± 5%;

[0031] And / or, the usage ratio of the sodium hydride and the dimethylformamide is 1g sodium hydride: 20ml±2ml dimethylformamide.

[0032] In some embodiments, nickel, bipyridine, and 1,5-cyclooctadiene are dissolved in dimethylformamide, and then heated and stirred to obtain a first solution, wherein the reaction temperature is 80°C ± 5°C;

[0033] And / or, the first compound is dissolved in dimethylformamide to obtain a second solution, and then the first solution is slowly added dropwise to the second solution, and the mixture is heated and stirred to react, wherein the reaction temperature is 80°C±5°C.

[0034] In some embodiments, the first compound is dissolved in dimethylformamide to obtain a second solution, and then the first solution is slowly added dropwise to the second solution, heated and stirred to react, and after the reaction is completed, the reaction is cooled and filtered to obtain the intermediate reactant, and after the cooling and before the filtering, the following steps are further included:

[0035] Slowly add dilute hydrochloric acid dropwise under stirring until the solution becomes a transparent green solution.

[0036] In some embodiments, in the step of dissolving nickel, bipyridine, and 1,5-cyclooctadiene in dimethylformamide and then heating and stirring to obtain a first solution, the ratio of nickel to dimethylformamide is 1 g nickel: 12.5 ml ± 2.5 ml dimethylformamide;

[0037] And / or, in said dissolving the intermediate reactant in dichloromethane, the usage ratio of the intermediate reactant to the dichloromethane is 1g of the intermediate reactant: 100ml±10ml of dichloromethane.

[0038] In a third aspect, an embodiment of the present application also provides an application of an indolecarbazole-based hole transport material, wherein the indolecarbazole polyphosphate is used as a hole transport layer material in an organic solar cell or a perovskite solar cell; or the indolecarbazole polyphosphate is used as an interface modification on the basis of the original hole transport layer.

[0039] In some embodiments, the use of the polyindolecarbazole phosphate as an interface modification on the basis of the original hole transport layer includes:

[0040] dissolving the polyindolecarbazole phosphate in a solvent to obtain a polyindolecarbazole phosphate solution;

[0041] The polyindolecarbazole phosphate solution is evenly coated on the surface of the hole transport layer.

[0042] In some embodiments, after uniformly coating the polyindolecarbazole phosphate solution on the surface of the hole transport layer, the method comprises:

[0043] Heat treatment is performed to promote the volatilization of the solvent and the solidification of polyindolecarbazole phosphate to form a stable interface modification layer.

[0044] The hole transport material based on indole and carbazole provided in the embodiment of the present application, and its preparation method and application, the embodiment of the present application provides a hole transport material based on indole and carbazole (i.e., polyphosphate indole and carbazole), which has the advantages of good stability, excellent hole transport performance, good passivation effect, solution processability, good wettability and coating uniformity, and efficient photoelectric conversion efficiency. The embodiment of the present application also provides a method for preparing a hole transport material based on indole and carbazole, and the prepared hole transport material of indole and carbazole is applied to the hole transport layer of perovskite solar cells to improve the photovoltaic performance and stability of perovskite solar cells. The embodiment of the present application also provides an application of polyphosphate indole and carbazole material, that is, as a hole transport layer material in an organic solar cell or a perovskite solar cell, or for interface modification on the basis of the original hole transport layer.

[0045] This is because, due to its excellent film-forming properties and interactions between macromolecular chains, polyindolecarbazole phosphate has greatly improved compactness and diffusivity compared to traditional small molecule indolecarbazole phosphate, thereby improving stability. In particular, polyindolecarbazole phosphate, combined with indium tin oxide as a conductive substrate, has a shorter interface spacing and a larger coverage factor and better interface compatibility after combining with indium tin oxide, thereby enhancing the electron adsorption capacity. Polyindolecarbazole phosphate is synthesized by polymerizing small molecule indolecarbazole phosphoric acid and has good conductivity, which makes it insensitive to coating thickness and surface roughness of conductive glass. Traditional small molecule indolecarbazole phosphate-type hole transport materials may affect their hole transport performance due to changes in coating thickness and substrate roughness. The phosphate group of polyindolecarbazole phosphate can form a chemical bond with conductive glass, which not only enhances the binding ability with conductive glass, but also helps to passivate the perovskite layer and inhibit charge recombination at the interface of the perovskite active layer / hole transport layer. This strong binding ability helps to improve the stability and efficiency of hole transport. Compared with traditional highly hydrophobic materials such as polybis(4-phenyl)(2,4,6-trimethylphenyl)amine, polyindolecarbazole phosphate can better wet the perovskite precursor solution, which makes large-area preparation easier and feasible.

[0046] The self-assembled monolayer based on 3-BPIC not only significantly improves the hole selectivity, but also reduces the interface impedance, effectively inhibits non-radiative recombination, and thus improves the stability of the device. In addition, the polyindolecarbazole phosphate material can be easily dissolved in a variety of single or mixed solvents, such as toluene, chlorobenzene, chloroform, dichloromethane, methanol, ethanol and isopropanol, which makes it more flexible and convenient in the preparation process. By polymerizing small molecule carbazole phosphate, its molecular weight is increased, thereby significantly improving the film-forming property on the surface of the conductive substrate, further enhancing the stability and performance of the device.

[0047] Among them, 3-BPIC represents a specific molecular structure. 3-BPIC is a class of self-assembled monolayer bisphosphonic acid molecules with adjustable dipole moment. Here, "bisphosphonic acid" refers to the presence of two phosphonic acid groups in the molecule. 3-BPIC molecules may have a specific axially symmetrical or centrosymmetric structure, which helps them form an ordered self-assembled monolayer on a specific surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 Schematic diagram of the process of the method for preparing a hole transport material based on indolecarbazole provided in an embodiment of the present application;

[0050] Figure 2 4 is a graph showing the relationship between the concentration of indolecarbazole polyphosphate and the open circuit voltage in the application example of the present application. DETAILED DESCRIPTION

[0051] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0052] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0053] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0054] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0055] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0056] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0057] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0058] The present application embodiment provides a hole transport material based on indolecarbazole, which is selected from at least one of Formula 1, Formula 2, Formula 3 and Formula 4. The structural formulas of the compounds of Formula 1, Formula 2, Formula 3 and Formula 4 are as follows:

[0059]

[0060] Wherein, n is 2-10000, and m is 1-100.

[0061] The hole transport material based on indole and carbazole provided in the embodiment of the present application is polyphosphate indole and carbazole, which has a significant improvement in compactness and diffusivity compared to traditional small molecule phosphate indole and carbazole, thereby improving stability. In particular, polyphosphate indole and carbazole is combined with indium tin oxide as a conductive substrate, and its shorter interface spacing and larger coverage factor and better interface compatibility after combining indium tin oxide enhance the electron adsorption capacity. Polyphosphate indole and carbazole is synthesized by polymerizing indole and carbazole phosphate small molecules, and has good conductivity, which makes it insensitive to coating thickness and conductive glass surface roughness. Traditional small molecule phosphate indole and carbazole hole transport materials may affect their hole transport performance due to changes in coating thickness and substrate roughness. The phosphate group of polyphosphate indole and carbazole can form a chemical bond with conductive glass, which not only enhances the ability to bind to conductive glass, but also helps to passivate the perovskite layer and inhibit the charge recombination at the interface of the perovskite active layer / hole transport layer. This strong binding ability helps to improve the stability and efficiency of hole transport.

[0062] In application, the value of n in the above compounds can be any value within the range of 2 to 10000, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 1000, 10000, etc., and the value of m can be any value within the range of 1 to 100, such as 1, 2, 3, 4, 5, 6, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, etc.

[0063] In applications, the hole transport material based on indole and carbazole can be only one of the four isomers of indole and carbazole polyphosphate, that is, any one of Formula 1, Formula 2, Formula 3 or Formula 4. In some embodiments, the hole transport material based on indole and carbazole can also be a combination of Formula 1 and Formula 2, a combination of Formula 1 and Formula 3, a combination of Formula 1 and Formula 4, a combination of Formula 2 and Formula 4, a combination of Formula 2 and Formula 3, and a combination of Formula 3 and Formula 4. In some embodiments, the hole transport material based on indole and carbazole can also be a combination of Formula 1, Formula 2 and Formula 3, a combination of Formula 1, Formula 3 and Formula 4, and a combination of Formula 2, Formula 3 and Formula 4. In some embodiments, the hole transport material based on indole and carbazole can also be a combination of Formula 1, Formula 2, Formula 3 and Formula 4.

[0064] It can be seen from the structural formulas of Formula 1, Formula 2, Formula 3 and Formula 4 that they are all symmetrical structures, and the self-assembled monolayers (SAMs) based on 3-BPIC not only significantly improve the hole selectivity, but also reduce the interface impedance, effectively inhibit the non-radiative recombination, and thus improve the stability of the device. In addition, the polyindole phosphate and carbazole material can be easily dissolved in a variety of single or mixed solvents, such as toluene, chlorobenzene, chloroform, dichloromethane, methanol, ethanol and isopropanol, which makes it more flexible and convenient in the preparation process. By polymerizing small molecule carbazole phosphate, its molecular weight is increased, thereby significantly improving the film-forming property on the surface of the conductive substrate, further enhancing the stability and performance of the device.

[0065] It should be noted that 3-BPIC represents a specific molecular structure. 3-BPIC is a type of self-assembled monolayer of bisphosphonic acid molecules with adjustable dipole moment. Here, "bisphosphonic acid" refers to the presence of two phosphonic acid groups in the molecule. 3-BPIC molecules may have a specific axially symmetrical or centrosymmetric structure, which helps them form an ordered self-assembled monolayer on a specific surface.

[0066] In some embodiments, the hole transport material based on indolecarbazole is indolecarbazole polyphosphate, wherein the indolecarbazole polyphosphate includes at least one of formula a to formula h in the monomers of the following structural formulas:

[0067]

[0068]

[0069] The value range of i is 1 to 40;

[0070] Furthermore, Rx is independently selected from at least one of a hydrogen atom, a halogen group, a cyano group, an alkyl group, an aromatic group, and a cyclic group.

[0071] In the application, the halogen group is any one of fluorine (F), chlorine (C1), bromine (Br) or iodine (I). The alkyl group is selected from (C1-C40) straight chain alkyl (carbon atoms are 1 to 40), (C3-C40) branched chain alkyl (carbon atoms are 3 to 40) or (C3-C40) cycloalkyl (carbon atoms are 3 to 40), and in the alkyl group, one or more non-adjacent carbon atoms (C) are optionally replaced by -O-, -S-, -C(O)-, -C(O-)O-, -OC(O)-, -OC(O)-O-, -CR 0 =CR 00 - or -C=C- substitution, where R 0 and R 00Independently, it is a straight chain alkyl, a branched alkyl or a cycloalkyl. In the alkyl, one or more hydrogen atoms are optionally replaced by F, Cl, Br, I or a cyano group (CN). The aromatic group is selected from aryl, heteroaryl, aryloxy, heteroaryloxy, arylcarbonyl, heteroarylcarbonyl, arylcarbonyloxy, heteroarylcarbonyloxy, aryloxycarbonyl or heteroaryloxycarbonyl, and it has 4 to 30 ring atoms.

[0072] The present invention provides a method for preparing a hole transport material based on indolecarbazole, comprising the following steps:

[0073] S10, providing halogenated phosphate indolecarbazole, a silanization agent, alcohols and a solvent;

[0074] S20, dissolving the halogenated phosphate indolecarbazole in a solvent to carry out copolymerization reaction to obtain an intermediate reactant;

[0075] S30, adding a silanization agent and an alcohol to the intermediate reactant for hydrolysis to obtain indolecarbazole polyphosphate, which is an indolecarbazole-based hole transport material.

[0076] In some embodiments, the halogenated phosphate indolecarbazole is dissolved in the solvent for copolymerization to obtain an intermediate reactant, and the main body of the copolymerization reaction is the halogenated phosphate indolecarbazole, that is, the halogenated phosphate indolecarbazole undergoes self-polymerization.

[0077] In some embodiments, the reaction time of the copolymerization reaction is 0.1 h to 72 h. In some embodiments, the reaction time of the copolymerization reaction can also be 0.1 h, 0.5 h, 1 h, 2 h, 4 h, 8 h, 10 h, 12 h, 24 h, 36 h, 48 h, 72 h, etc., any value within the range of 0.1 h to 72 h.

[0078] In some embodiments, the reaction temperature of the copolymerization reaction is 50° C. to 200° C. In some embodiments, the reaction temperature of the copolymerization reaction can also be 50° C., 60° C., 70° C., 80° C., 100° C., 120° C., 150° C., 180° C., 200° C., or any other temperature within the range of 50° C. to 200° C.

[0079] In some embodiments, the alcohol includes at least one of methanol, ethanol, and propanol.

[0080] In some embodiments, the solvent includes one of dimethylformamide, toluene, chlorobenzene, xylene, and tetrahydrofuran.

[0081] In some embodiments, the step of dissolving the halogenated phosphate indolecarbazole in a solvent for copolymerization to obtain an intermediate reactant comprises:

[0082] S21. Under a nitrogen environment, dissolving 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and sodium hydride in dimethylformamide, and then adding diethyl-4-bromobutylphosphonic acid to react. After the reaction is completed, extraction and concentration are performed, and the crude product is purified by column chromatography to obtain a first compound;

[0083] S22, dissolving nickel, bipyridine and 1,5-cyclooctadiene in dimethylformamide, and then heating and stirring to obtain a first solution;

[0084] S23, dissolving the first compound in dimethylformamide to obtain a second solution, then slowly dropping the first solution into the second solution, heating and stirring to react, and cooling and filtering after the reaction to obtain an intermediate reactant.

[0085] In some embodiments, in step S30, the silanization agent and the alcohol are added to the intermediate reactant for hydrolysis to obtain polyphosphate indolecarbazole, wherein the polyphosphate indolecarbazole is the indolecarbazole-based hole transport material comprising:

[0086] The intermediate reactant is dissolved in dichloromethane, and then trimethylsilyl bromide is added dropwise, and stirred at room temperature. After the reaction is completed, excess methanol is added dropwise, and then the indolecarbazole-based hole transport material is obtained by vacuum distillation, concentration, precipitation, filtration and washing.

[0087] The preparation method of the hole transport material based on indole and carbazole provided in the embodiment of the present application, first, uses nickel catalyst and specific reaction conditions, such as nitrogen environment and specific solvent (dimethylformamide and dichloromethane), can realize efficient and highly selective reaction. This ensures that the reaction path can be accurately controlled during the synthesis process to obtain the target product. Second, by stepwise reaction and accurate control of reaction conditions (such as temperature, solvent, catalyst dosage, etc.), the process of each step of the reaction can be accurately controlled, thereby realizing accurate regulation of product structure and properties. Third, in the synthesis process, by extraction, concentration, column chromatography purification and other steps, impurities can be effectively removed and the purity of the product can be improved. High-purity products are crucial for preparing high-performance hole transport materials.

[0088] In some embodiments, the reaction formula of the method for preparing the hole transport material based on indolecarbazole includes the following two reaction formulas, one of which is:

[0089]

[0090] The final polyphosphate indolecarbazole is obtained by polymerizing the raw material 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and then reducing it. In the application, the value range of n is 2 to 1000000, and the value range of m is 1 to 40.

[0091] The second is:

[0092]

[0093] The raw material 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole is first reduced and then polymerized to obtain polyphosphate indolecarbazole. In the application, the value range of n is 2 to 1000000, and the value range of m is 1 to 40. It should be noted that the reaction formula of the preparation method of the hole transport material based on indolecarbazole includes but is not limited to the above two methods, and in some embodiments, it can also be synthesized by other methods. In some embodiments, in step S21, before dissolving 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and sodium hydride in dimethylformamide, it also includes:

[0094] Nitrogen is replaced several times to prevent sodium hydride from reacting with oxygen or moisture in the air, thereby ensuring the safety of the reaction and the purity of the product.

[0095] In some embodiments, the purity of sodium hydride is 60% ± 5%. This is because the chemical properties of high-purity sodium hydride are relatively active and dangerous during use. Therefore, within the purity range of 60% ± 5%, the chemical properties of sodium hydride are relatively stable, which is convenient for the safe conduct of the reaction. In some embodiments, the amount ratio of sodium hydride and dimethylformamide is 1g sodium hydride: 20ml ± 2ml dimethylformamide. That is, 20 milliliters of dimethylformamide (DMF) are required to dissolve every 1 gram of sodium hydride. This ratio is to ensure that sodium hydride can be completely dissolved in DMF, thereby forming a uniform reaction system.

[0096] In step S21, the extraction operation specifically includes adding ice water and ethyl acetate for extraction multiple times, specifically, adding 500 mL of ice water, adding 500 mL of ethyl acetate three times, and extracting three times. The addition of ice water is to reduce the temperature of the system, so that the first compound is more easily precipitated at low temperature or reduce its solubility in water, which is beneficial to the subsequent extraction operation. Using ethyl acetate as an extractant, the system is extracted three times. 500 mL of ethyl acetate is used each time, and the system is mixed evenly by shaking or stirring, and then allowed to stand for stratification. The ethyl acetate layer usually contains the target compound or most of it, while the water layer contains water-soluble impurities. Repeating the extraction three times is to increase the concentration of the target compound in the ethyl acetate layer, thereby increasing the recovery rate. The concentration operation includes concentrating with anhydrous magnesium sulfate. The column chromatography operation specifically includes using silica gel as a chromatographic filler, with a mesh number of 200 to 300 meshes, and using a chromatographic column with a width of 5 cm and a length of 25 cm for separation. A gradient column PE→PE:DCM=15:1 eluent gradient is used. Initially, pure petroleum ether was used as the eluent, and then the proportion of dichloromethane was gradually increased until the ratio of PE to DCM reached 15: 1. This gradient elution was to elute the first compound and impurities one by one according to their different adsorption capacities on silica gel, thereby achieving separation.

[0097] In some embodiments, in step S22, nickel, bipyridine, and 1,5-cyclooctadiene are dissolved in dimethylformamide, and then heated and stirred to obtain a first solution, and the amount ratio of nickel to dimethylformamide is 1g nickel: 12.5ml±2.5ml dimethylformamide. In this way, this ratio can usually ensure that nickel and its complexes have good solubility in DMF, which is conducive to the reaction. The appropriate amount of DMF can provide sufficient reaction medium to allow sufficient contact between the reactants and improve the reaction efficiency. The DMF dosage range of ±2.5ml provides a certain degree of operational flexibility, allowing fine-tuning according to specific circumstances in actual operation to adapt to different reaction conditions or experimental requirements.

[0098] In some embodiments, in step S22, nickel, bipyridine, and 1,5-cyclooctadiene are dissolved in dimethylformamide, and then heated and stirred to obtain a first solution, wherein the reaction temperature is 80°C±5°C; and in step S23, the first compound is dissolved in dimethylformamide to obtain a second solution, and then the first solution is slowly added dropwise to the second solution, and the reaction is heated and stirred to carry out the reaction, wherein the reaction temperature is 80°C±5°C.

[0099] Within the temperature range of 80℃±5℃, the reaction rate is neither too fast nor too slow, which is conducive to the control of the reaction process. A too fast reaction rate may make the reaction difficult to control and produce by-products; while a too slow reaction rate may prolong the reaction time and reduce production efficiency. Dimethylformamide has good stability within this temperature range and will not decompose or produce by-products that are unfavorable to the reaction due to excessively high temperatures. Appropriate temperature is conducive to the formation of the target product and reduces the formation of by-products. At a temperature of 80℃±5℃, the selectivity of the reaction may be higher, which is conducive to obtaining intermediate reactants with higher purity.

[0100] In some embodiments, in step S23, the first compound is dissolved in dimethylformamide to obtain a second solution, and then the first solution is slowly added dropwise to the second solution, heated and stirred to react, and after the reaction is completed, cooled and filtered to obtain an intermediate reactant, and after cooling and before filtering, the following steps are further included:

[0101] Slowly add dilute hydrochloric acid under stirring until the solution becomes a transparent green solution. The benefits of this treatment step are: First, it can quench the catalyst: nickel catalyst is used in the reaction, and the addition of dilute hydrochloric acid can neutralize or quench the activity of the catalyst to prevent it from continuing to catalyze the reaction in subsequent steps, thereby ensuring the end point of the reaction and the purity of the product. Second, remove impurities: the addition of dilute hydrochloric acid may help remove alkaline impurities or unreacted raw materials in the reaction system, which may affect the purity of the product and subsequent treatment steps. Third, promote product precipitation: for some reactions, the addition of dilute hydrochloric acid may change the pH value of the solution, which is conducive to the precipitation of the product from the solution and improve the yield and purity of the product. Fourth, it is easy to handle: a transparent green solution usually indicates that the impurities in the reaction system have been effectively removed, which is conducive to subsequent filtering, washing, drying and other steps, reducing the difficulties and losses in subsequent treatment. Fifth, safety considerations: in some cases, unquenched catalysts or unreacted raw materials may be dangerous. By adding dilute hydrochloric acid, the risks of these substances can be reduced and the safety of the entire reaction process can be improved. Finally, it is easy to monitor: the solution turning into transparent green can serve as a clear sign of the reaction endpoint, making it easier for experimenters to monitor the progress of the reaction and judge the completion of the reaction.

[0102] In some embodiments, in step S30, when the intermediate reactant is dissolved in dichloromethane, the ratio of the intermediate reactant to dichloromethane is 1g of the intermediate reactant: 100ml±10ml of dichloromethane. This ratio can usually ensure that the intermediate reactant has good solubility in dichloromethane, so that the compound can be fully dissolved in the solvent, which is convenient for subsequent experimental operations, such as filtration, extraction, etc.

[0103] The embodiments of the present application also provide an application of an indolecarbazole-based hole transport material, using indolecarbazole polyphosphate as a hole transport layer material in an organic solar cell or a perovskite solar cell; or using indolecarbazole polyphosphate as an interface modification on the basis of the original hole transport layer.

[0104] In this way, the introduction of polyindolecarbazole phosphate can enhance the interface contact between the hole transport layer and the perovskite active layer, optimize the energy level matching, and reduce the interface resistance. Through interface modification, the hole extraction efficiency and transmission rate can be improved, thereby improving the overall performance of the perovskite battery.

[0105] In some embodiments, polyindolecarbazole phosphate is used as an interface modification on the basis of the original hole transport layer, including:

[0106] dissolving polyindolecarbazole phosphate in a solvent to obtain a polyindolecarbazole phosphate solution;

[0107] The polyindolecarbazole phosphate solution is evenly coated on the surface of the hole transport layer. The solvent includes but is not limited to at least one of toluene, chlorobenzene, chloroform, dichloromethane, methanol, ethanol and isopropanol. The polyindolecarbazole phosphate material can be easily dissolved in the above-mentioned multiple single or mixed solvents.

[0108] In the application, the polyindolecarbazole phosphate solution is evenly coated on the surface of the hole transport layer by spin coating, blade coating or other appropriate coating techniques.

[0109] In some embodiments, after the polyindolecarbazole phosphate solution is uniformly coated on the surface of the hole transport layer, the following steps are performed:

[0110] Heat treatment is performed to promote the volatilization of the solvent and the solidification of polyindolecarbazole phosphate to form a stable interface modification layer.

[0111] The following describes the invention in conjunction with specific embodiments.

[0112] Example 1

[0113] The present invention provides an indolecarbazole-based hole transport material and a preparation method thereof, wherein the preparation method comprises the following steps:

[0114] S10. Under nitrogen environment, 1eq of 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and 4eq of 60% pure sodium hydride were dissolved in dimethylformamide, wherein 1g of sodium hydride: 20mL of DMF, and then 2.5eq of diethyl-4-bromobutylphosphonic acid was added to react for 2h. After the reaction, 500mL of ice water was added, and 500mL*3 of ethyl acetate was extracted three times, and then concentrated with anhydrous magnesium sulfate, and column chromatography was performed to obtain the first compound, wherein the yield of the first compound was 65%; the parameters of column chromatography include: silica gel was used as the chromatographic filler, and the mesh number was 200-300 meshes, and a chromatographic column with a width of 5cm and a length of 25cm was used for separation. A gradient column was used with an eluent gradient of PE→PE:DCM=15:1;

[0115] S20, dissolving 0.05 eq nickel, 0.1 eq bipyridine, and 0.25 eq 1,5-cyclooctadiene in dimethylformamide, wherein 1 g of Ni is dissolved in 12.5 mL of DMF, and then stirring at 80° C. for 0.5 h to obtain a first solution;

[0116] S30, 1eq of the first compound was dissolved in dimethylformamide to obtain a second solution, wherein 1g of Ni: 12.5mL of DMF, and then the first solution was slowly added dropwise to the second solution, stirred at 80°C for 24h, cooled to room temperature after the reaction, and diluted hydrochloric acid was slowly added dropwise under stirring until it was dissolved into a transparent green solution, and the suspended solid was filtered to obtain an intermediate reactant with a yield of 78%;

[0117] S40, dissolving the intermediate reactant in dichloromethane, wherein 1g of polyphosphate indolecarbazole: 100mL of dichloromethane, then dropping 10eq of trimethylsilyl bromide, stirring at room temperature for 24h, after the reaction is completed, dropping excess methanol to remove excess trimethylsilyl bromide, then vacuum distilling and concentrating, precipitating, filtering and rinsing to obtain the indolecarbazole-based hole transport material, and the yield is 77%.

[0118] Example 2

[0119] The present invention provides an indolecarbazole-based hole transport material and a preparation method thereof, wherein the preparation method comprises the following steps:

[0120] S10. Under nitrogen environment, 0.8eq of 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and 3.9eq of 60% pure sodium hydride were dissolved in dimethylformamide, wherein 1g of sodium hydride: 20mL of DMF, and then 2.3eq of diethyl-4-bromobutylphosphonic acid was added to react for 2h. After the reaction, 500mL of ice water was added, and 500mL*3 of ethyl acetate was extracted three times, and then concentrated with anhydrous magnesium sulfate, and column chromatography was performed to obtain the first compound, wherein the yield of the first compound was 65%; the parameters of column chromatography include: silica gel was used as the chromatographic filler, and the mesh number was 200-300 meshes, and a chromatographic column with a width of 5cm and a length of 25cm was used for separation. A gradient column was used with an eluent gradient of PE→PE:DCM=15:1;

[0121] S20, dissolving 0.05 eq nickel, 0.05 eq bipyridine, and 0.20 eq 1,5-cyclooctadiene in dimethylformamide, wherein 1 g of Ni is dissolved in 12.5 mL of DMF, and then stirring at 80° C. for 0.5 h to obtain a first solution;

[0122] S30, 0.9eq of the first compound was dissolved in dimethylformamide to obtain a second solution, wherein 1g of Ni: 12.5mL of DMF, and then the first solution was slowly added dropwise to the second solution, stirred at 80°C for 24h, cooled to room temperature after the reaction, and diluted hydrochloric acid was slowly added dropwise under stirring until it was dissolved into a transparent green solution, and the suspended solid was filtered to obtain an intermediate reactant with a yield of 78%;

[0123] S40, dissolving the intermediate reactant in dichloromethane, wherein 1g of polyphosphate indolecarbazole: 100mL of dichloromethane, then dropping 8eq of trimethylsilyl bromide, stirring at room temperature for 24h, after the reaction is completed, dropping excess methanol to remove excess trimethylsilyl bromide, then vacuum distilling and concentrating, precipitating, filtering and rinsing to obtain the indolecarbazole-based hole transport material, and the yield is 77%.

[0124] Example 3

[0125] The present invention provides an indolecarbazole-based hole transport material and a preparation method thereof, wherein the preparation method comprises the following steps:

[0126] S10. Under nitrogen environment, 1.2eq of 13,9-bromo-5,7-dihydroindole[2,3-b]carbazole and 4.1eq of 60% pure sodium hydride were dissolved in dimethylformamide, wherein 1g of sodium hydride: 20mL of DMF, and then 2.7eq of diethyl-4-bromobutylphosphonic acid was added to react for 2h. After the reaction, 500mL of ice water was added, and 500mL*3 of ethyl acetate was extracted three times, and then concentrated after anhydrous magnesium sulfate, and column chromatography was performed to obtain the first compound, wherein the yield of the first compound was 65%; the parameters of column chromatography include: silica gel was used as the chromatographic filler, and the mesh number was 300 meshes, and a chromatographic column with a width of 5cm and a length of 25cm was used for separation. A gradient eluent gradient of PE→PE:DCM=15:1 was used for the column;

[0127] S20, dissolving 0.05 eq nickel, 0.15 eq bipyridine, and 0.30 eq 1,5-cyclooctadiene in dimethylformamide, wherein 1 g of Ni is dissolved in 12.5 mL of DMF, and then stirring at 80° C. for 0.5 h to obtain a first solution;

[0128] S30, 1.1eq of the first compound was dissolved in dimethylformamide to obtain a second solution, wherein 1g of Ni: 12.5mL of DMF, and then the first solution was slowly added dropwise to the second solution, stirred at 80°C for 24h, cooled to room temperature after the reaction, and diluted hydrochloric acid was slowly added dropwise under stirring until it dissolved into a transparent green solution, and the suspended solid was filtered to obtain an intermediate reactant with a yield of 78%;

[0129] S40, dissolving the intermediate reactant in dichloromethane, wherein 1g of polyphosphate indolecarbazole: 100mL of dichloromethane, then dropping 12eq of trimethylsilyl bromide, stirring at room temperature for 24h, after the reaction is completed, dropping excess methanol to remove excess trimethylsilyl bromide, then distilling and concentrating under reduced pressure, precipitating, filtering and rinsing to obtain the indolecarbazole-based hole transport material, and the yield is 77%.

[0130] It should be noted that eq (equivalent) is a term used in chemistry to refer to the mass ratio of substances when they interact. It is used to indicate the equivalent amount of a substance reacting chemically with another substance. Specifically, it refers to the amount of a chemical substance when its valence or redox valence is equal to the stoichiometric charge number. In the above embodiments, it can be understood as parts by weight.

[0131] Application Example 1

[0132] The specific preparation process of applying indolecarbazole-based hole transport materials to perovskite solar cells is as follows:

[0133] (1) Cut the fluorine-doped tin oxide transparent conductive glass into squares with a side length of 1.5 cm and etch them according to the electrode requirements using a photolithography machine;

[0134] (2) Prepare 6 ml of 75% diisopropyl di(acetylacetonate)titanate solution, 4 ml of acetylacetone, and 90 ml of anhydrous ethanol mixed solution and stir overnight for use as the solution required for the dense layer;

[0135] (3) Mix titanium dioxide slurry and anhydrous ethanol in a mass ratio of 1:6 and stir overnight to obtain the solution required for the mesoporous layer;

[0136] (4) Dissolve 1.1 mol of PbI2, 1.0 mol of FAI, 0.2 mol of PbBr2, and 0.2 mol of MABr in DMSO / DMF (volume ratio of 1:4) and stir the solution overnight to obtain (FAPbI3) 0.85 (MAPbBr3) 0.15 Perovskite precursor solution;

[0137] (5) Dissolve 80 mg of Spiro-OMeTAD in 875.1 ml of chlorobenzene, add 31.6 μl of tert-butylpyridine, 18.1 μl of acetonitrile solution of lithium bis(trifluoromethylsulfonylimide) (500 mg / ml) and 7.83 μl of acetonitrile solution of FK209 (300 mg / ml) in sequence, and stir for four hours;

[0138] (6) Weigh 30 mg, 40 mg, 50 mg, 60 mg, 70 mg, and 80 mg of three hole transport materials, respectively, and dissolve them in 1 ml of chlorobenzene. Then, add 19.75 μl of TBP, 11.32 μl of Li-TFSI acetonitrile solution (500 mg / ml), and 4.90 μl of FK209 acetonitrile solution (300 mg / ml) in turn, and stir for four hours.

[0139] (7) Use tap water containing detergent, deionized water, acetone, and ethanol to ultrasonically clean the conductive glass for 20 minutes, and place it in an 80°C air drying oven to dry it for later use;

[0140] (8) Use an ear cleaning bulb to clean the conductive surface and then treat with ozone for 30 minutes;

[0141] (9) All prepared solutions except the mesoporous layer solution were filtered with a syringe filter (polytetrafluoroethylene filter membrane, pore size 0.22 μm) before use;

[0142] (10) using a spray gun to evenly spray the mixed solution prepared in step (2) onto a conductive glass substrate preheated at 450° C., heating at 450° C. for 30 minutes and then cooling naturally to obtain a dense titanium dioxide layer;

[0143] (11) The mixed solution prepared in step (3) is evenly spin-coated on the sintered titanium dioxide dense layer using a spin coater at a speed of 5000 for 30 seconds, first heated at 100° C. for 10 minutes, and then sintered at 500° C. for 1 hour to obtain a mesoporous titanium dioxide layer;

[0144] (12) Take 25 μl of the perovskite precursor solution and evenly spread it on the sintered mesoporous titanium dioxide layer. Spin-coat the perovskite precursor solution evenly on the mesoporous titanium dioxide layer by a two-step method of 1000 rpm for 10 seconds and 5000 rpm for 30 seconds. In the last 10 seconds of the second step, quickly add 120 μl of chlorobenzene as an anti-solvent. The spin-coated film is annealed at 100 °C for 1 hour to obtain a perovskite film.

[0145] (13) Take 25 μl of the prepared three hole transport materials and Spiro OMeTAD solution and spin coat them onto the sintered perovskite film at a speed of 5000 and a process parameter of 30 seconds; use a vacuum coating machine to evaporate a gold electrode with a thickness of about 80 nm on the above-mentioned film spin-coated with the hole transport material to produce a perovskite solar cell.

[0146] Performance Testing

[0147] The performance of the perovskite solar cell prepared according to the corresponding example was tested (the battery test area was 0.0625cm 2 ), the test results are as attached Figure 2 And the following table shows:

[0148]

[0149] As shown in the table above, perovskite solar cells based on polyindolecarbazole phosphate (Poly-3-BPIC) as a hole transport layer can achieve a photoelectric conversion efficiency of 19.00%, which exceeds the control group based on small molecule indolecarbazole phosphate (3-BPIC), and the perovskite solar cells based on polyindolecarbazole phosphate are not sensitive to the concentration of polyindolecarbazole phosphate.

[0150] As attached Figure 2 As shown, in the application of organic solar cells, polyindolecarbazole phosphate is used as the hole transport layer material, and the photoelectric conversion efficiency of the device reaches 19.00%, showing a significant performance improvement.

[0151] The following excellent effects are achieved based on polyindolecarbazole phosphate as a hole transport layer material provided in the embodiments of the present application:

[0152] Polyindolecarbazole phosphate has the advantages of good stability, excellent hole transport performance, good passivation effect, solution processability, good wettability and coating uniformity, and high photoelectric conversion efficiency.

[0153] Due to its excellent film-forming properties and interactions between macromolecular chains, polyindolecarbazole phosphate has greatly improved compactness and diffusivity compared to traditional indolecarbazole phosphate small molecules, thereby improving stability. In particular, polyindolecarbazole phosphate (poly-3-BPIC), combined with indium tin oxide as a conductive substrate, has a shorter interfacial spacing and a larger coverage factor and better interfacial compatibility after combining with indium tin oxide, thereby enhancing the electron adsorption capacity. Polyindolecarbazole phosphate is synthesized by polymerizing indolecarbazole phosphate small molecules and has good conductivity, which makes it insensitive to coating thickness and conductive glass surface roughness. Traditional small molecule indolecarbazole phosphate hole transport materials may affect their hole transport performance due to changes in coating thickness and substrate roughness. The phosphate group of polyindolecarbazole phosphate can form a chemical bond with conductive glass, which not only enhances the binding ability with conductive glass, but also helps to passivate the perovskite layer and inhibit charge recombination at the interface of the perovskite active layer / hole transport layer. This strong binding ability helps to improve the stability and efficiency of hole transport.

[0154] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A hole transport material based on indolecarbazole, characterized in that: At least one selected from the group consisting of Formula 1, Formula 2, Formula 3 and Formula 4, wherein the structural formulas of the compounds of Formula 1, Formula 2, Formula 3 and Formula 4 are as follows: Among them, n is 2 to 10000, and m is 1 to 100.

2. The indolecarbazole-based hole transport material according to claim 1, characterized in that The hole transport material based on indolecarbazole is indolecarbazole polyphosphate, wherein the indolecarbazole polyphosphate includes at least one of the monomers of the following structural formula: The value range of i is 1 to 40; The Rx is independently selected from at least one of a hydrogen atom, a halogen group, a cyano group, an alkyl group, an aromatic group, and a cyclic group.

3. A method for preparing a hole transport material based on indolecarbazole, characterized in that: include: Providing halogenated phosphate indole and carbazole, silanization reagent, alcohol and solvent; dissolving the halogenated phosphate indolecarbazole in the solvent to carry out copolymerization reaction to obtain an intermediate reactant; The silanization agent and the alcohol are added to the intermediate reactant for hydrolysis to obtain indolecarbazole polyphosphate, which is the indolecarbazole-based hole transport material.

4. The preparation method according to claim 3, characterized in that: The reaction time of the copolymerization reaction is 0.1h to 72h.

5. The preparation method according to claim 3, characterized in that: The reaction temperature of the copolymerization reaction is 0°C to 300°C.

6. The preparation method according to claim 3, characterized in that: The alcohol includes at least one of methanol, ethanol and propanol.

7. The preparation method according to claim 3, characterized in that: The solvent includes one of dimethylformamide, toluene, chlorobenzene, xylene and tetrahydrofuran.

8. An application of a hole transport material based on indolecarbazole, characterized in that: The indolecarbazole-based hole transport material is indolecarbazole polyphosphate, and the indolecarbazole polyphosphate is used as a hole transport layer material in an organic solar cell or a perovskite solar cell; or the indolecarbazole polyphosphate is used as an interface modification on the basis of an original hole transport layer.

9. The use according to claim 8, characterized in that The method of using the polyindolecarbazole phosphate as an interface modification on the basis of the original hole transport layer includes: dissolving the polyindolecarbazole phosphate in a solvent to obtain a polyindolecarbazole phosphate solution; The polyindolecarbazole phosphate solution is evenly coated on the surface of the hole transport layer.

10. The use according to claim 9, characterized in that After the polyindolecarbazole phosphate solution is uniformly coated on the surface of the hole transport layer, the method comprises: Heat treatment is performed to promote the volatilization of the solvent and the solidification of polyindolecarbazole phosphate to form a stable interface modification layer.

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