Hole transport material and preparation method thereof, solar cell and optoelectronic device

Abstract

The invention relates to the technical field of photovoltaic cells, in particular to a hole transport material and a preparation method thereof, a solar cell and an optoelectronic device. The hole transport material comprises a hole transport polymer, and the hole transport polymer has at least one of repetitive units with structures as shown in formulas (I)-(II). The hole transport material provided by the invention can effectively passivate defects in a perovskite thin film, not only can reduce non-radiative recombination and carrier loss, but also can regulate and control the crystallization rate of the perovskite thin film and improve the quality of the perovskite thin film, thereby improving the photoelectric conversion efficiency of a perovskite solar cell; according to the invention, no extra dopant needs to be added, the cost is reduced, the side reaction is reduced, and the interaction of the long-chain structure of the polymer and the guanidyl group and the perovskite can stabilize crystal lattices and inhibit ion migration, so that the efficiency and stability of the perovskite solar cell are improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a hole transport material and a preparation method thereof, a solar cell, and an optoelectronic device. Background Art

[0002] Perovskite solar cells have attracted widespread attention due to their many advantages, including long carrier diffusion length, high absorption coefficient, adjustable band gap, compatibility with multiple fabrication methods, and ease of fabrication. The hole transport layer (HTL), a key component, extracts holes generated in the perovskite layer and transports them to the electrodes, preventing backflow in the cell.

[0003] However, conventional hole transport materials suffer from insufficient hole extraction capacity. Furthermore, the poor wettability of the perovskite solution on the hole transport layer results in poor perovskite film quality and defects, leading to severe non-radiative recombination at the perovskite / hole transport layer interface, compromising the photovoltaic conversion efficiency and long-term stability of solar cells. Summary of the Invention

[0004] Based on this, it is necessary to provide a hole transport material and its preparation method, solar cell, optoelectronic device, improve the hole extraction ability, improve the perovskite film quality, reduce defects, reduce non-radiative recombination at the interface, and improve the photoelectric conversion efficiency and long-term stability of solar cells.

[0005] The first aspect of the present application provides a hole transport material, which includes a hole transport polymer, wherein the hole transport polymer has at least one of the repeating units of the structures represented by formula (I) to formula (II):

[0006]

[0007] Formula (I);

[0008]

[0009] Formula (II);

[0010] In formula (I) to formula (II), X1 and X2 are each independently selected from C2-C8 alkylene, or ; Y is selected from a single bond, a sulfur atom or is absent.

[0011] In some embodiments, the hole transport polymer comprises a homopolymer formed by repeating units of one of the structures represented by formula (I) and formula (II).

[0012] In some embodiments, the hole transport polymer includes at least one compound represented by Formula TM1 to Formula TM8:

[0013] 、 、 、 、 、 、 、 ;

[0014] Wherein, m is an integer from 2 to 8; n represents the number of repeating units, and n>1.

[0015] In some embodiments, at least a portion of the hole transport polymer is a copolymer comprising at least one repeating unit of the structures represented by formula (I) and formula (II).

[0016] In some embodiments, the weight average molecular weight M of the hole transport polymer is w It is 994 g / mol~100000000 g / mol.

[0017] The second aspect of the present application provides a method for preparing a hole transport material, which comprises the following steps: S1, reacting a dihalogenated aromatic amine compound with a guanidine halide to prepare an intermediate compound; S2, polymerizing the intermediate compound to prepare a hole transport polymer; wherein the dihalogenated aromatic amine compound comprises at least one of the compounds represented by the structures of formula (III) to formula (IV):

[0018]

[0019] Formula (III);

[0020]

[0021] Formula (IV);

[0022] The guanidinyl halide comprises at least one compound of the structure represented by formula (V):

[0023]

[0024] Formula (V);

[0025] The intermediate compound includes at least one of the compounds represented by formula (VI) to formula (VII):

[0026]

[0027] Formula (VI);

[0028]

[0029] Formula (VII);

[0030] The hole transport polymer comprises at least one of the repeating units represented by formula (I) to formula (II):

[0031]

[0032] Formula (I);

[0033]

[0034] Formula (II);

[0035] In formula (I) to formula (VII), X is X1 or X2; X1 and X2 are each independently selected from a single bond, a C1-C8 alkylene group, or ; Y is selected from a single bond, a sulfur atom or does not exist; Z is Cl, Br or I.

[0036] In some embodiments, step S2 specifically comprises the following steps: S21, reacting the intermediate compound with a tert-butoxycarbonyl protecting agent to prepare a tert-butoxycarbonyl-protected intermediate compound; S22, polymerizing the tert-butoxycarbonyl-protected intermediate compound, and then removing the tert-butoxycarbonyl group by acid catalysis to prepare a hole transport polymer; wherein the tert-butoxycarbonyl-protected intermediate compound comprises at least one of the compounds represented by the structures of formula (VIII) to formula (IX):

[0037]

[0038] Formula (VIII);

[0039]

[0040] Formula (IX).

[0041] In some embodiments, step S1 specifically includes the following steps: mixing a dihalogenated aromatic amine compound and a guanidinium halide with a solvent, and reacting them in the presence of a palladium catalyst, a ligand, and an alkaline auxiliary agent to prepare an intermediate compound.

[0042] In some embodiments, in step S2, the polymerization reaction is performed in the presence of a nickel catalyst and a ligand.

[0043] A third aspect of the present application provides a solar cell, which includes the hole transport material provided in the first aspect or the hole transport material prepared by the preparation method of the hole transport material provided in the second aspect.

[0044] The fourth aspect of the present application provides an optoelectronic device, which includes the hole transport material provided by the first aspect or the hole transport material prepared by the preparation method of the hole transport material provided by the second aspect.

[0045] Compared with traditional technologies, this application has at least the following beneficial effects:

[0046] The hole transport material provided in the present application comprises a hole transport polymer having a repeating unit represented by formula (I), and the guanidine group and the conjugated aromatic amine group in the repeating unit have a synergistic effect. On the one hand, compared with the single amino group of the organic amine small molecule, the guanidine group with a multidentate structure can interact more strongly with the perovskite; at the same time, the guanidine group is embedded in the conjugated aromatic amine structure. Compared with the monolayer guanidine material, more guanidine groups can be faced to the perovskite layer and tightly cover the bottom interface of the perovskite layer, thereby improving the interface wettability of the perovskite layer / hole transport layer, thereby improving the defect passivation effect, improving the quality of the perovskite film, reducing the non-radiative recombination of the interface, and thus improving the photoelectric conversion efficiency and long-term stability of the device.

[0047] On the other hand, the introduction of the guanidine group provides a charge-rich functional group on the conjugated polymer chain, which can effectively block electron backflow, inhibit non-radiative recombination, and promote hole extraction. At the same time, the -NH and =NH in the guanidine group can form a five-membered or six-membered cyclic hydrogen bond closed structure. The planar configuration formed thereby enhances the π-π stacking and improves its HOMO energy level, making it closer to the top energy level of the valence band of the perovskite, thereby optimizing the energy level matching between the hole transport layer and the perovskite and enhancing its hole extraction ability.

[0048] Therefore, the hole transport material provided in the present application can improve the hole extraction ability without the need for additional dopants, thereby reducing costs. The structure of the long polymer chain and the interaction between the guanidine group and the perovskite can stabilize the lattice and inhibit ion migration, thereby improving the photoelectric conversion efficiency and long-term stability of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes currently understood for these applications. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the accompanying drawings:

[0050] Figure 1 Schematic diagram of the process for preparing hole transport materials in one embodiment of the present application.

[0051] Figure 2 These are the ultraviolet absorption spectra of the hole transport materials TM1, TM2, and TM3 in Examples 1 to 3 of the present application.

[0052] Figure 3This is a comparison diagram of the energy levels of hole transport materials TM1, TM2, and TM3 in Examples 1 to 3 of the present application.

[0053] Figure 4 Schematic diagram comparing the contact angles of the perovskite solution on the hole transport layer formed by the hole transport materials TM1 and TM2 in Examples 1 and 2 of the present application.

[0054] Figure 5 Schematic diagram of SEM cross-section comparison of the hole transport layer and the perovskite layer formed by the hole transport materials TM1 and TM2 in Examples 1 and 2 of the present application.

[0055] Figure 6 Graphs of IV testing of perovskite solar cells prepared based on the hole transport materials TM1, TM2, and TM3 in Examples 1 to 3 of the present application.

[0056] Figure 7 Graphs showing the efficiency decay of perovskite solar cells prepared based on the hole transport materials TM1, TM2, and TM3 in Examples 1 to 3 of the present application. DETAILED DESCRIPTION

[0057] References to embodiments of the present application will now be provided in detail, one or more examples of which are described below. Each example is provided to illustrate, not to limit, the present application. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment may be used in another embodiment to produce further embodiments.

[0058] Therefore, it is intended that this application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present application are disclosed in or are apparent from the following detailed description. Those skilled in the art will appreciate that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0059] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0060] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0061] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0062] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0063] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0064] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0065] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0066] Explanation of terms:

[0067] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0068] The term "alkyl" refers to a saturated hydrocarbon containing primary (normal) carbon atoms, secondary carbon atoms, tertiary carbon atoms, quaternary carbon atoms, or combinations thereof. A phrase containing this term, for example, "C1-C9 alkyl," refers to an alkyl group containing 1 to 9 carbon atoms, each occurrence of which may independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, or C9 alkyl. Suitable examples include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(C H3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (- CH2CH2CH(CH3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH( )2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3 and octyl (-(CH2)7CH3).

[0069] The term "alkylene" refers to a hydrocarbon group having two monovalent radical centers derived from an alkyl group by removing a hydrogen atom, which can be a saturated branched alkyl group or a saturated straight-chain alkyl group. For example, "C1-C9 alkylene" means that the alkyl portion contains 1 to 9 carbon atoms, and each occurrence can be independently C1 alkylene, C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene, C8 alkylene, or C9 alkylene. Suitable examples include, but are not limited to, methylene (-CH2-), 1,1-ethyl (-CH(CH3)-), 1,2-ethyl (-CH2CH2-), 1,1-propyl (-CH(CH2CH3)-), 1,2-propyl (-CH2CH(CH3)-), 1,3-propyl (-CH2CH2CH2-), and 1,4-butyl (-CH2CH2CH2CH2-).

[0070] Currently, the most widely used hole transport materials include 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD), poly(3-hexylthiophene) (P3HT), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). PTAA, a conjugated amine polymer, has been widely used in perovskite solar cells due to its excellent film-forming properties and hole selectivity.

[0071] However, PTAA exhibits poor stability under hot and humid conditions and is susceptible to moisture corrosion, leading to mechanical failure and delamination of the interface. Furthermore, PTAA's inherently low hole mobility limits its effective carrier transport, necessitating the use of dopants (such as MoO3) to enhance its charge transport capacity and interfacial carrier extraction efficiency.

[0072] In recent years, in order to improve the performance of the perovskite layer / hole transport layer interface, organic amine small molecules are usually introduced to inhibit non-radiative recombination through their coordination with perovskite surface defects.

[0073] However, the applicant found that this type of small molecule material generally has the following problems: (1) Organic amine small molecules themselves do not have the ability to transport holes, which easily hinders the extraction of carriers; (2) Organic amine small molecules have poor structural stability, are easy to absorb moisture and decompose, and are difficult to withstand long-term operating conditions, which in turn affects the long-term stability of the device; (3) Due to the limited distribution of small molecules on the interface, the passivation layer they form is often discontinuous and has poor wettability, which causes the perovskite solution to easily produce defects such as holes and cracks at the bottom interface during the film formation process, which not only weakens the passivation effect, but also forms charge recombination centers, affecting the efficiency and life of the device.

[0074] In order to solve the above technical problems, the first aspect of the present application provides a hole transport material, which includes a hole transport polymer, and the hole transport polymer has at least one of the repeating units of the structures represented by formula (I) to formula (II):

[0075]

[0076] Formula (I);

[0077]

[0078] Formula (II);

[0079] In formula (I) to formula (II), X1 and X2 are each independently selected from C2-C8 alkylene, or ; Y is selected from a single bond, a sulfur atom or is absent.

[0080] The hole transport material provided in the present application, the hole transport polymer has a repeating unit shown in formula (I), and the guanidine group and the conjugated aromatic amine group in the repeating unit have a synergistic effect. On the one hand, compared with the single amino group of the organic amine small molecule, the guanidine group with a multidentate structure can interact more strongly with the perovskite; at the same time, the guanidine group is embedded in the conjugated aromatic amine structure. Compared with the single-molecule layer guanidine material, more guanidine groups can be faced to the perovskite layer and tightly cover the bottom interface of the perovskite layer, thereby improving the interface wettability of the perovskite layer / hole transport layer, thereby improving the defect passivation effect, improving the quality of the perovskite film and the bonding strength between the perovskite layer and the hole transport layer, reducing the non-radiative recombination at the interface, and thus improving the photoelectric conversion efficiency and long-term stability of the device.

[0081] On the other hand, the introduction of the guanidine group provides a charge-rich functional group on the conjugated polymer chain, which can effectively block electron backflow, inhibit non-radiative recombination, and promote hole extraction. At the same time, the -NH and =NH in the guanidine group can form a five-membered or six-membered cyclic hydrogen bond closed structure. The planar configuration formed thereby enhances the π-π stacking and improves its HOMO energy level, making it closer to the top energy level of the valence band of the perovskite, thereby optimizing the energy level matching between the hole transport layer and the perovskite and enhancing its hole extraction ability.

[0082] Therefore, the hole transport material provided in the present application can improve the hole extraction ability without the need for additional dopants, thereby reducing costs. The structure of the long polymer chain and the interaction between the guanidine group and the perovskite can stabilize the lattice and inhibit ion migration, thereby improving the photoelectric conversion efficiency and long-term stability of the perovskite solar cell.

[0083] In some embodiments, the hole transport polymer comprises a homopolymer formed by repeating units of one of the structures represented by formula (I) and formula (II).

[0084] In some embodiments, the hole transport polymer includes at least one compound represented by Formula TM1 to Formula TM8:

[0085] 、 、 、 、 、 、 、 ;

[0086] wherein m is an integer from 2 to 8; n represents the number of repeating units, and n>1. In some embodiments, X1 and X2 are each independently selected from or In this way, by introducing structural units with rigid and conjugated properties, such as benzene rings or benzothiadiazole groups, the planarity and rigidity of the polymer can be significantly improved, thereby enhancing the π-π stacking effect between polymer chains, which is beneficial to improving the hole transport ability of the material and improving battery efficiency. In addition, the conjugated polymer constructed with rigid conjugated units can still maintain its hole transport performance when the thickness of the hole transport layer is increased, which is conducive to commercial large-scale preparation and expands the process window.

[0087] In some embodiments, Y is selected from a single bond or a sulfur atom. This improves the planarity and rigidity of the polymer, thereby enhancing the π-π stacking interaction between polymer chains, which helps improve the material's hole transport capacity and battery efficiency. Furthermore, conjugated polymers constructed with rigid conjugated units can maintain their hole transport performance even when the thickness of the hole transport layer is increased, facilitating commercial large-scale production and expanding the process window.

[0088] In some embodiments, at least a portion of the hole transport polymer is a copolymer comprising at least one repeating unit of the structures represented by formula (I) and formula (II).

[0089] In some embodiments, the copolymer further comprises other repeating units.

[0090] It is understood that the present application does not limit other repeating units. For example, other repeating units may be triphenylamine groups, carbazole groups, benzocarbazole groups, or phenothiazine groups.

[0091] In some embodiments, the weight average molecular weight M of the hole transport polymer is wis 994 g / mol to 100,000,000 g / mol. For example, the weight average molecular weight M of the hole transport polymer is w It can be, but is not limited to, 994 g / mol, 1000 g / mol, 10000 g / mol, 100000 g / mol, 1000000 g / mol, 100000000 g / mol, and 1000000000 g / mol.

[0092] The second aspect of the present application provides a method for preparing a hole transport material, such as Figure 1 As shown, the preparation method comprises the following steps:

[0093] S1. A dihalogenated aromatic amine compound reacts with a guanidinyl halide to prepare an intermediate compound.

[0094] S2. The intermediate compound undergoes a polymerization reaction to prepare a hole transport polymer.

[0095] Among them, the dihalogenated aromatic amine compound includes at least one of the compounds represented by formula (III) to formula (IV):

[0096]

[0097] Formula (III);

[0098]

[0099] Formula (IV);

[0100] The guanidinyl halide comprises at least one compound of the structure represented by formula (V):

[0101]

[0102] Formula (V);

[0103] The intermediate compound includes at least one of the compounds represented by formula (VI) to formula (VII):

[0104]

[0105] Formula (VI);

[0106]

[0107] Formula (VII);

[0108] The hole transport polymer comprises at least one of the repeating units represented by formula (I) to formula (II):

[0109]

[0110] Formula (I);

[0111]

[0112] Formula (II);

[0113] In formula (I) to formula (VII), X is X1 or X2; X1 and X2 are each independently selected from C2-C8 alkylene, or ; Y is selected from a single bond, a sulfur atom or does not exist; Z is Cl, Br or I.

[0114] The preparation method of the hole transport material provided in the present application first reacts a dihalogenated aromatic amine compound with a guanidine halide to form an intermediate compound, and then obtains a hole transport polymer through a polymerization reaction, thereby achieving efficient integration of the guanidine and aromatic amine structures, simplifying the synthesis steps, and having mild reaction conditions and high yields. The obtained polymer structure is highly controllable, which is conducive to the subsequent regulation of its electronic structure and interface properties.

[0115] In some embodiments, step S2 specifically includes the following steps:

[0116] S21. The intermediate compound reacts with a tert-butyloxycarbonyl protecting agent to prepare a tert-butyloxycarbonyl protected intermediate compound.

[0117] S22. After the tert-butyloxycarbonyl protected intermediate compound undergoes polymerization, the tert-butyloxycarbonyl group is removed by acid catalysis to prepare a hole transport polymer.

[0118] The tert-butyloxycarbonyl protected intermediate compound includes at least one of the compounds represented by formula (VIII) to formula (IX):

[0119]

[0120] Formula (VIII);

[0121]

[0122] Formula (IX).

[0123] Thus, in step S21, the guanidine group in the intermediate compound is pre-protected using a tert-butyloxycarbonyl (BOC) protecting agent, which can effectively inhibit unnecessary side reactions between the amino group in the guanidine group and other active groups under the polymerization reaction conditions; in step S22, the tert-butyloxycarbonyl protecting group is removed by acid catalysis after the polymerization is completed, which can release the guanidine functional group under mild conditions, restore its activity and arrange it in a good orientation facing the perovskite interface, thereby giving the hole transport polymer excellent interface wettability and defect passivation ability, thereby improving the efficiency and stability of the device.

[0124] In some embodiments, step S1 specifically includes the following steps: mixing a dihalogenated aromatic amine compound and a guanidinium halide with a solvent, and reacting them in the presence of a palladium catalyst, a ligand, and an alkaline auxiliary agent to prepare an intermediate compound.

[0125] In this way, by carrying out the reaction in the presence of a palladium catalyst and an alkaline auxiliary agent, the coupling process between the guanidine halide and the dihalogenated aromatic amine compound can be effectively promoted, the yield and purity of the target intermediate compound can be improved, and the guanidine group can be effectively grafted onto the aromatic amine skeleton, laying the structural foundation for the subsequent construction of a hole transport polymer with a synergistic effect.

[0126] In some embodiments, in step S1, the reaction temperature is 80°C to 130°C.

[0127] In some embodiments, the palladium catalyst is selected from one of palladium acetate, palladium dichloride, tris(dibenzylideneacetone)dipalladium, tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium dichloride and 1,1'-bis(diphenylphosphino)ferrocenepalladium chloride.

[0128] In some embodiments, the ligand is selected from one of tri-tert-butylphosphine, triphenylphosphine, tri(p-tolyl)phosphine, tricyclohexylphosphine and 1,1′-bis(diphenylphosphino)ferrocene.

[0129] In some embodiments, the alkaline auxiliary agent is selected from one of sodium tert-butoxide, potassium carbonate, sodium carbonate, potassium acetate and sodium acetate.

[0130] In some embodiments, in step S2, the polymerization reaction is carried out in the presence of a nickel catalyst and a ligand. Thus, the nickel catalyst provides a metal active center, and the ligand coordinates with the nickel metal center to form a nickel complex. The ligands cooperate with each other to form a catalytically active center, which promotes a specific dehalogenation coupling polymerization reaction between the monomers to form a hole transport polymer.

[0131] In some embodiments, in step S2, the polymerization reaction temperature is 90° C. to 130° C., and the time is 3 h to 24 h.

[0132] In some embodiments, the nickel catalyst is selected from one of Ni(COD)2 and Ni(bpy)Cl2.

[0133] In some specific embodiments, when the nickel catalyst is Ni(COD)2, the ligand is 2,2-bipyridine.

[0134] A third aspect of the present application provides a solar cell, which includes the hole transport material provided in the first aspect or the hole transport material prepared by the preparation method of the hole transport material provided in the second aspect.

[0135] In some embodiments, a solar cell includes a hole transport layer, and the hole transport layer includes the above-mentioned hole transport material.

[0136] In some embodiments, the solar cell is a perovskite solar cell. The perovskite solar cell includes a perovskite layer disposed on a hole transport layer. This application does not limit the specific structure of the solar cell; in one embodiment, the solar cell includes one of a single perovskite cell, a perovskite / perovskite tandem cell, a perovskite / crystalline silicon tandem cell, a perovskite / organic tandem cell, and a perovskite / copper indium gallium selenide tandem cell.

[0137] The hole transport layer can be prepared by conventional methods in the art, including but not limited to sol-gel method, spin coating method, spray coating method, doctor blade method and slit coating method.

[0138] In some embodiments, the hole transport layer is prepared by dissolving the aforementioned hole transport material in an organic solvent to prepare a hole transport layer solution; the hole transport layer solution is then coated on a substrate and annealed to prepare the hole transport layer. The concentration of the hole transport material in the hole transport layer solution is 0.1 mg / mL to 10 mg / mL; the organic solvent is chloroform, chlorobenzene, toluene, methanol, ethanol, or a mixture thereof.

[0139] In some embodiments, the chemical formula of the material of the perovskite layer satisfies ABX3 or A2CDX6, where A is an inorganic, organic, or organic / inorganic mixed cation, which may be at least one of MA, FA, and Cs; B is an inorganic, organic, or organic / inorganic mixed cation, which may be at least one of Pb and Sn; C is an inorganic, organic, or organic / inorganic mixed cation, which is commonly Ag. + D is an inorganic, organic or organic-inorganic mixed cation, which can be a bismuth cation Bi 3+ 、Antimony cation Sb 3+ , and indium cations In 3+ X is an inorganic, organic, or organic / inorganic mixed anion, which can be at least one of Br or I. The perovskite layer has a band gap of 1.20 eV to 2.30 eV.

[0140] The perovskite layer can be prepared by conventional technical means in the field, and can also be prepared by the following method: weigh the material of the perovskite layer, dissolve it in a solvent (for example, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc.), stir evenly, filter, and take the supernatant; cover the supernatant on the prepared electron transport layer or hole transport layer, and the covering method can be spin coating using a spin coater, wherein the rotation speed can be 500 rpm~5000 rpm, the spin coating time can be 5~50 seconds, and annealing is performed after spin coating, the annealing temperature can be 80℃~150℃, and the annealing time can be 0min~60min. After annealing, the perovskite layer is obtained.

[0141] The thickness of the perovskite layer can be any thickness used in the art. Optionally, the thickness of the perovskite layer is 200 nm to 1000 nm.

[0142] In some embodiments, the solar cell is an organic solar cell.

[0143] In some embodiments, the solar cell is an inverted solar cell. The solar cell further includes a substrate, and the hole transport layer is disposed on the substrate.

[0144] Generally speaking, the structure of an inverted solar cell includes a substrate, a hole transport layer, a perovskite layer, an electron transport layer and an electrode layer in sequence; that is, the incident light passes through the substrate, the hole transport layer, the perovskite layer, the electron transport layer and the electrode layer in sequence.

[0145] In some embodiments, the substrate is selected from one of a crystalline silicon cell, a conductive glass, and a flexible conductive film.

[0146] In some embodiments, the crystalline silicon cell includes one of a passivated emitter and back contact cell (PERC cell), a tunneling oxide passivated contact cell (TOPCon cell), a crystalline silicon heterojunction solar cell (HJT cell), and an interlayer back contact cell (IBC cell).

[0147] In some embodiments, the conductive glass has a certain degree of transparency. The conductive glass is generally composed of a glass substrate and a conductive layer of an oxide thin film (TCO). Commonly used TCOs include, but are not limited to, the following materials: fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), and indium zinc oxide (IZO). The conductive glass is generally any conductive glass used in the art. Conductive glass is commercially available. The conductive glass needs to be cleaned before use, for example, by ultrasonic cleaning with a detergent, deionized water, and ethanol.

[0148] In some embodiments, the flexible conductive film includes one of an indium tin oxide (ITO) film, a fluorine-doped tin oxide (FTO) film, an aluminum-doped zinc oxide (AZO) film, a boron-doped zinc oxide (BZO) film, and an indium zinc oxide (IZO) film.

[0149] In some embodiments, the material of the electron transport layer includes [6,6]-phenyl C 61 Methyl butyrate (PC61BM), [6,6]-phenyl C 71 Methyl butyrate (PC71BM), fullerene C 60 (C 60 ), Fullerene C 70 (C 70 ), tin dioxide (SnO2), zinc oxide (ZnO), titanium dioxide (TiO2) and derivatives of the above substances, or one or more materials obtained by doping or passivation.

[0150] The electron transport layer can be prepared using conventional methods in the art, or by the following method: dissolving the electron transport layer material in an organic solvent (e.g., chlorobenzene, dichlorobenzene, toluene, or xylene) to prepare a solution with a concentration of 5 mg / mL to 50 mg / mL. The solution is then coated on the surface of the conductive glass or perovskite layer by spin coating using a spin coater at a speed of 500 to 5000 rpm for 5 to 50 seconds. Annealing is then performed after spin coating at a temperature of 80°C to 150°C for 5 to 60 minutes. The electron transport layer is then prepared.

[0151] The thickness of the electron transport layer can be any thickness used in the art. Optionally, the thickness of the electron transport layer is 10 nm to 100 nm.

[0152] The electrode layer can be any electrode used in the art. Optionally, the electrode layer can be made of an organic, inorganic, or mixed conductive material, including but not limited to the following: Ag, Cu, C, Au, and Al. The electrode layer can be prepared by vapor deposition.

[0153] The thickness of the electrode layer can be any thickness used in the art. Optionally, the thickness of the electrode layer is 10 nm to 200 nm.

[0154] The solar cell provided in this application can be used in, but is not limited to, electrical devices such as vehicles, ships, or aircraft.

[0155] An embodiment of the present application provides an electric device, which may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0156] The fourth aspect of the present application provides an optoelectronic device, which includes the hole transport material provided by the first aspect or the hole transport material prepared by the preparation method of the hole transport material provided by the second aspect.

[0157] In some embodiments, the optoelectronic device may be a field effect transistor, a light emitting diode, a photodetector, etc.; in the field effect transistor, the hole transport material is used as an organic semiconductor material; in the light emitting diode and the photodetector, it is used as a hole transport layer and a hole injection layer, or as an interface modification layer based on the original hole transport layer and hole injection layer.

[0158] The present application will be further described below with reference to specific embodiments and comparative examples.

[0159] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. All reagents or instruments used without specifying the manufacturer are commercially available conventional products.

[0160] Example 1

[0161] Hole transport materials:

[0162] The hole transport material is a hole transport polymer. The preparation method of the hole transport polymer is as follows:

[0163]

[0164] (1) Dissolve 3.25 g of bis(4-bromophenyl)amine and 2.1 g of 1-(4-bromophenyl)guanidine in 50 mL of a mixed solution of ultra-dry toluene and dimethylformamide, add 100 mg of palladium acetate and 150 mg of tri-tert-butylphosphine, and 4.2 g of sodium tert-butoxide, and stir at 120 °C under a nitrogen atmosphere for 12 hours. TLC plate shows that the raw materials have reacted. After cooling to room temperature, concentrate under reduced pressure, pour into water, add 10 mL of saturated sodium carbonate solution, stir thoroughly, extract with dichloromethane, take the organic phase, dry, concentrate under reduced pressure, and pass through a column to obtain 2.6 g of the intermediate compound N,N-(4-bromodiphenyl)phenyl-4-guanidine, the structural formula of which is as follows:

[0165] ;

[0166] The NMR test data of N,N-(4-bromodiphenyl)phenyl-4-guanidine are as follows: 1 H NMR (400MHz, CDCl3,ppm): 7.56 (d, 8.5 Hz, 4H), 6.84 (d, J=6.8 Hz, 4H), 6.56 (d, 6.5 Hz, 2H), 6.25 (d, 6.4 Hz, 3H), 4.58 (m, 4H); 13 C NMR (400 MHz, CDCl3, ppm): 146.3,142.3, 140.5, 129.6, 122.1,120.6, 109.0.

[0167] (2) 2 g of N,N-(4-bromodiphenyl)phenyl-4-guanidine and 4.8 g of di-tert-butyl dicarbonate were dissolved in 20 mL of a mixed solvent of water and tetrahydrofuran, and 2.5 g of sodium bicarbonate was added. The mixture was stirred at room temperature for 12 hours under a nitrogen atmosphere. TLC plate showed that the raw materials had reacted completely. The mixture was concentrated under reduced pressure and poured into water. 10 mL of saturated sodium carbonate solution was added and stirred thoroughly. The mixture was extracted with dichloromethane. The organic phase was dried and concentrated under reduced pressure. The mixture was passed through a column to obtain 1.8 g of the tert-butyloxycarbonyl-protected intermediate compound N,N-(4-bromodiphenyl)phenyl-4-Boc-guanidine, the structural formula of which is as follows:

[0168]

[0169] The NMR test data of N,N-(4-bromodiphenyl)phenyl-4-Boc-guanidine are as follows: 1 H NMR (400MHz, CDCl3,ppm): 7.52 (d, 8.5 Hz, 4H), 6.78 (d, J=6.8 Hz, 4H), 6.54 (d, 6.5 Hz, 2H), 6.28 (d, 6.4 Hz, 3H), 4.42 (m, 4H), 1.18 (s, 18H); 13 C NMR (400 MHz, CDCl3, ppm): 144.8, 140.5, 140.1, 128.6, 123.8, 120.6, 109.0.

[0170] (3) 200 mg of the product N,N-(4-bromodiphenyl)phenyl-4-Boc-guanidine was dissolved in 5 mL of bipyridine and 10 mL of DMF, and 2 mg of Ni(COD)2 was added and heated to 120°C and stirred for 12 hours. The obtained solution was concentrated under reduced pressure and added dropwise to n-hexane to obtain a solid which was filtered and dried to obtain the polymer product X1 with the following structural formula:

[0171]

[0172] Theory C 31 H 38 N4O4(%): C, 70.16; H, 7.22; N, 10.56; O, 12.06. Actual C 31 H 38 N4O4 (%): C, 70.16; H, 7.22; N, 10.56; O, 12.06.

[0173] (4) 100 mg of polymer product X1 was dissolved in 10 mL of methanol and 5 mL of trifluoroacetic acid and stirred at room temperature for 12 hours. After the reaction was completed, the mixture was filtered, concentrated under reduced pressure, and then concentrated with methanol to remove excess trifluoroacetic acid to obtain polymer product TM1, with the following structural formula:

[0174] ;

[0175] Theory C 21 H 22 N4(%): C, 76.33; H, 6.71; N, 16.96. Actual C 31 H 38 N4O4 (%): C, 8.64; H, 7.32; N, 14.04.

[0176] Among them, the weight average molecular weight M of the hole transport polymer is w It is 127269.

[0177] Solar cells:

[0178] 0.5 mg of hole transport material was weighed and dissolved in 1 mL of chlorobenzene to obtain a hole transport layer solution; the hole transport layer solution (60 μL) was then spin-coated on an ITO conductive glass at a speed of 3000 rpm / s, annealed at 100°C for 5 minutes, and cooled to room temperature to form a hole transport layer with a thickness of 7 nm; a perovskite layer, an electron transport layer, and an electrode layer were sequentially prepared on the hole transport layer to obtain a solar cell, wherein the perovskite layer includes FA 0.95 Cs 0.05 PbI3 material, the electron transport layer includes C 60Materials, the electrode layer includes Ag metal.

[0179] Example 2

[0180] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0181] The hole transport material is TM2, and the structural formula of TM2 is as follows:

[0182] ;

[0183] Where m=2, the weight average molecular weight of the hole transport polymer M w It is 205450.

[0184] Example 3

[0185] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0186] The hole transport material is TM3, and the structural formula of TM3 is as follows:

[0187] ;

[0188] Where m=2, the weight average molecular weight of the hole transport polymer M w It is 187262.

[0189] Example 4

[0190] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0191] The hole transport material is TM4, and the structural formula of TM4 is as follows:

[0192] ;

[0193] Where m=2, the weight average molecular weight of the hole transport polymer M w It is 176802.

[0194] Example 5

[0195] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0196] The hole transport material is TM5, and the structural formula of TM5 is as follows:

[0197] ;

[0198] Where m=2, the weight average molecular weight of the hole transport polymer M w It is 148840.

[0199] Example 6

[0200] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0201] The hole transport material is TM6, and the structural formula of TM6 is as follows:

[0202] ;

[0203] Among them, the weight average molecular weight M of the hole transport polymer is w It is 165153.

[0204] Example 7

[0205] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0206] The hole transport material is TM7, and the structural formula of TM7 is as follows:

[0207] ;

[0208] Among them, the weight average molecular weight M of the hole transport polymer is w It is 127552.

[0209] Example 8

[0210] The preparation method of the hole transport material and solar cell in this embodiment is basically the same as that in Example 1, except that:

[0211] The hole transport material is TM8, and the structural formula of TM8 is as follows:

[0212] ;

[0213] Among them, the weight average molecular weight M of the hole transport polymer is w It is 146210.

[0214] Comparative Example 1

[0215] Hole transport materials:

[0216] Commercially available PTAA material (manufacturer: Sigma-Aldrich). The weight average molecular weight of PTAA is M w It is 300,000.

[0217] Solar cells:

[0218] 0.5 mg of hole transport material was weighed and dissolved in 1 mL of chlorobenzene to obtain a hole transport layer solution; the hole transport layer solution (60 μL) was then spin-coated on an ITO conductive glass at a speed of 3000 rpm / s, annealed at 100°C for 5 minutes, and cooled to room temperature to form a hole transport layer with a thickness of 7 nm; a perovskite layer, an electron transport layer, and an electrode layer were sequentially prepared on the hole transport layer to obtain a solar cell, wherein the perovskite layer includes FA 0.95 Cs 0.05 PbI3 material, the electron transport layer includes C 60 Materials, the electrode layer includes Ag metal.

[0219] Comparative Example 2

[0220] Hole transport materials:

[0221] PTAA material (manufacturer: Sigma-Aldrich) and guanidine in a mass ratio of 1:1. The weight average molecular weight of PTAA is M w It is 300,000.

[0222] Solar cells:

[0223] 0.5 mg of hole transport material was weighed and dissolved in 1 mL of chlorobenzene to obtain a hole transport layer solution; the hole transport layer solution (60 μL) was then spin-coated on an ITO conductive glass at a speed of 3000 rpm / s, annealed at 100°C for 5 minutes, and cooled to room temperature to form a hole transport layer with a thickness of 7 nm; a perovskite layer, an electron transport layer, and an electrode layer were sequentially prepared on the hole transport layer to obtain a solar cell, wherein the perovskite layer includes FA 0.95 Cs 0.05 PbI3 material, the electron transport layer includes C 60 Materials, the electrode layer includes Ag metal.

[0224] Performance Testing

[0225] (1) UV absorption test

[0226] The UV absorption spectra of hole transport materials TM1, TM2 and TM3 were obtained by UV-vis tester. Figure 2 The maximum absorption peak of PTAA is between 290nm and 300nm. Figure 2 As shown in the figure, compared with the PTAA material, the ultraviolet absorption of TM1, TM2 and TM3 has a certain red shift.

[0227] (2) Energy level test

[0228] The HOMO energy levels of the hole transport materials TM1, TM2, and TM3 in Examples 1 to 3 were obtained by ultraviolet photoelectron spectroscopy (UPS). Figure 3 .like Figure 3 As shown in the figure, the energy levels of polymers TM1, TM2, and TM3 can better adapt to the energy levels of perovskite compared to traditional PTAA materials (HOMO energy level is about -5.2eV).

[0229] (3) Contact angle test

[0230] The contact angle test was conducted on the surface of the hole transport layer prepared in the above examples and comparative examples using a perovskite solution. The perovskite material in the perovskite solution was FA 0.95 Cs 0.05 The concentration of PbI3 perovskite solution is 1 mg / mL. The test results are shown in Table 1 and Figure 4 .like Figure 4 As shown, the perovskite solution is within ten degrees in TM1 and TM2, indicating that the wettability of the TM1 and TM2 hole transport materials synthesized in this scheme to the perovskite solution has been greatly improved.

[0231] (4) SEM test

[0232] The SEM cross-section comparison diagram of the hole transport layer and the perovskite layer formed by the hole transport materials TM1 and TM2 in Example 1 and Example 2 was obtained by using a SEM tester. Figure 5 .like Figure 5 As shown, in the present application, a perovskite film is prepared on the hole transport layer formed by TM1 or TM2, and the cross-sectional holes are greatly reduced and the crystallization quality of the film is significantly improved.

[0233] (5) Photoelectric performance test

[0234] The solar cells prepared in the above embodiments and comparative examples were placed in a solar simulator (manufacturer: Wavelabs). Under the irradiation of one sunlight intensity, a bias voltage (Vp, bias voltage range is -0.1 to 1.2 V) was applied to the device using a test source meter and the device output current was tested to obtain a bias-current density curve.

[0235] Open circuit voltage (Voc): The terminal voltage of the cell when there is no load, that is, the current density in the bias-current density curve is 0 mA cm -2 The bias value at .

[0236] Short-circuit current density (Jsc): The output current per unit area of ​​the battery cell when it is short-circuited, that is, the current density when the bias voltage is 0V in the bias-current density curve.

[0237] Fill factor (FF): FF = max (Vp × Jsc),

[0238] Where Vp is the bias voltage and Jsc is the short-circuit current density.

[0239] Photovoltaic cell efficiency (PCE): PCE = Voc × Jsc × FF.

[0240] The test results of the above performance are shown in Table 1. Figure 6 and Figure 7 shown.

[0241] Table 1

[0242]

[0243] As shown in Table 1, Figure 4 、 Figure 6 and Figure 7 As shown, by comparing Examples 1 to 8 with Comparative Examples 1 to 2, it can be seen that the hole transport material provided in the present application improves the wettability to the perovskite solution, and the device performance of the perovskite solar cell is greatly improved.

[0244] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0245] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the technical concept of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A hole transport material, characterized in that The hole transport polymer comprises at least one of the repeating units of the structures represented by formula (I) to formula (II): Formula (I); Formula (II); In formula (I) to formula (II), X1 and X2 are each independently selected from C2-C8 alkylene, or ; Y is selected from a single bond, a sulfur atom or is absent.

2. The hole transport material according to claim 1, characterized in that The hole transport polymer comprises a homopolymer formed by one of the repeating units of the structures represented by formula (I) and formula (II).

3. The hole transport material according to claim 2, characterized in that The hole transport polymer includes at least one of the compounds represented by Formula TM1 to Formula TM8: 、 、 、 、 、 、 、 ； Wherein, m is an integer from 2 to 8; n represents the number of repeating units, and n>1.

4. The hole transport material according to claim 1, characterized in that At least part of the hole transport polymer is a copolymer, and the copolymer includes at least one repeating unit of the structure represented by formula (I) and formula (II).

5. The hole transport material according to any one of claims 1 to 4, characterized in that The weight average molecular weight M of the hole transport polymer w It is 994 g / mol~100000000 g / mol.

6. A method for preparing a hole transport material, characterized in that: The following steps are involved: S1. reacting a dihalogenated aromatic amine compound with a guanidinium halide to prepare an intermediate compound; S2, the intermediate compound undergoes a polymerization reaction to prepare a hole transport polymer; Wherein, the dihalogenated aromatic amine compound includes at least one of the compounds represented by the structures of formula (III) to formula (IV): Formula (III); Formula (IV); The guanidinyl halide comprises at least one compound of the structure shown in formula (V): Formula (V); The intermediate compound includes at least one of the compounds represented by formula (VI) to formula (VII): Formula (VI); Formula (VII); The hole transport polymer comprises at least one of the repeating units represented by formula (I) to formula (II): Formula (I); Formula (II); In formula (I) to formula (VII), X is X1 or X2; X1 and X2 are each independently selected from a single bond, a C1-C8 alkylene group, or ; Y is selected from a single bond, a sulfur atom or does not exist; Z is Cl, Br or I.

7. The method for preparing a hole transport material according to claim 6, wherein: Step S2 specifically includes the following steps: S21, reacting the intermediate compound with a tert-butyloxycarbonyl protecting agent to prepare a tert-butyloxycarbonyl protected intermediate compound; S22, after the tert-butyloxycarbonyl-protected intermediate compound undergoes polymerization, the tert-butyloxycarbonyl group is removed by acid catalysis to prepare the hole transport polymer; Wherein, the tert-butyloxycarbonyl protected intermediate compound includes at least one of the compounds represented by formula (VIII) to formula (IX): Formula (VIII); Formula (IX).

8. The method for preparing a hole transport material according to claim 6 or 7, characterized in that: At least one of the following conditions is met: (1) Step S1 specifically comprises the following steps: mixing a dihalogenated aromatic amine compound and a guanidine halide with a solvent, and reacting them in the presence of a palladium catalyst, a ligand, and an alkaline auxiliary agent to prepare the intermediate compound; (2) In step S2, the polymerization reaction is carried out in the presence of a nickel catalyst and a ligand.

9. A solar cell, characterized in that: The hole transport material comprises the hole transport material according to any one of claims 1 to 5 or the hole transport material prepared by the preparation method of the hole transport material according to any one of claims 6 to 8.

10. An optoelectronic device, characterized in that: The hole transport material comprises the hole transport material according to any one of claims 1 to 5 or the hole transport material prepared by the preparation method of the hole transport material according to any one of claims 6 to 8.

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