Benzocarbazolyl self-assembly hole transport material and preparation method and application thereof

Abstract

The invention discloses a benzocarbazolyl self-assembly hole transport material and a preparation method and application thereof, and relates to the technical field of hole transport materials. The structural formula of the benzocarbazolyl self-assembly hole transport material is as follows: # imgabs0 #, wherein n is 2-6; in the formula (I), R is selected from C2-C5 heterocyclic groups, C6-C16 aryl groups, C6-C16 aryl groups substituted by at least one halogenated group, C6-C16 aryl groups substituted by at least one C1-C3 halogenated alkyl group, C2-C6 alkyl groups or C2-C6 alkyl groups substituted by at least one halogenated group. The benzocarbazolyl self-assembly hole transport material takes benzocarbazole as a core and a phosphonic acid group as an anchoring group, has good solubility and film-forming property, and can significantly improve the photoelectric conversion efficiency of a perovskite solar cell when being applied to the perovskite solar cell.

Description

Technical Field

[0001] This application relates to the technical field of hole transport materials. Specifically, it relates to a benzocarbazole-based self-assembled hole transport material, its preparation method and application. Background Art

[0002] With the intensification of the energy crisis and the increasingly serious environmental pollution problems, finding efficient and clean new energy has become an urgent task. Among numerous renewable energy sources, solar energy has attracted a great deal of attention due to its wide distribution range and the characteristic of being not restricted by regions. Converting solar energy into electrical energy through photovoltaic technology is gradually becoming the core way of future energy supply. In the past ten-odd years, new solar cells using perovskite materials as the light absorption layer have emerged and developed vigorously.

[0003] Perovskite solar cells (PSCs) are a typical thin-film solar cell, and the core of its structure includes key components such as a perovskite light absorption layer, a hole transport layer (HTL), an electron transport layer (ETL), and electrodes. According to the sequence of component deposition, PSCs devices can be divided into two types: normal structure (n-i-p) and inverted structure (p-i-n). Its operation mechanism is that the perovskite layer captures photon energy, promotes the valence band electrons to transition, and forms electron-hole pairs; subsequently, the electrons are introduced into the electron transport layer, while the holes enter the hole transport layer. After these electrons and holes are collected by the positive and negative electrodes, they are driven by the internal electric field formed by the positive and negative electrodes with different work functions to migrate, and then generate current.

[0004] PSCs are an ideal choice for constructing tandem solar cells (TSCs). Tandem solar cells are composed of two sub-cells with complementary absorption spectra in series, namely a wide-bandgap (WBG) and a narrow-bandgap (NBG) sub-cell. This design can break through the Shockley-Queisser theoretical efficiency limit (about 33%) faced by single-junction solar cells, and thus is expected to achieve higher energy conversion efficiency. According to theoretical predictions, whether it is a two-terminal tandem solar cell composed of perovskite / silicon composite or a tandem solar cell made entirely of perovskite material, its efficiency limit can approach 40%. Therefore, developing efficient and stable wide-bandgap perovskite solar cell sub-cells is crucial for achieving this high-efficiency goal.

[0005] Compared with conventional perovskite materials (whose optical bandgap E g is 1.59 eV), wide-bandgap (WBG) perovskites (with an optical bandgap between 1.68 and 1.8 eV) contain a higher halogen ratio, which often leads to frequent phase segregation phenomena and open-circuit voltage (V oc) significant losses. Therefore, during the growth of the perovskite layer, the hole transport layer (HTL) as the substrate plays a crucial role in the performance of the overall device. Currently, the most commonly used HTL material for WBG-type PSCs is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). However, the highest occupied molecular orbital (HOMO) energy level of PTAA is relatively shallow, approximately -5.1 eV, with a large energy level difference from the valence band maximum (VBM, lower than -5.7 eV) of WBG perovskite, resulting in significant voltage loss at the HTL-perovskite interface. In addition, the surface wettability of the PTAA film is poor, making it difficult to deposit a high-quality WBG perovskite film on it. In view of this, developing a new type of efficient HTL material for all-perovskite tandem solar cells (TSCs) has become an urgent task.

[0006] In recent years, self-assembled monolayers (SAMs) with anchoring groups (such as carboxyl groups, phosphonic acid groups, etc.) have received extensive attention. SAMs have been widely used in conventional (bandgap E g about 1.59 eV) inverted PSCs and organic solar cells due to their many advantages such as simple synthesis, high optical transmittance, and good processability in green solvents. Developing SAMs suitable for WBG-type PSCs is expected to further improve the efficiency of tandem solar cells. However, there are interfacial contact defects between the representative SAM hole transport materials such as (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB, CAS number: 2882156-63-8) and perovskite reported for WBG-type PSCs, which affect the further development of PSCs. Summary of the Invention

[0007] The main purpose of this application is to provide a benzocarbazole-based self-assembled hole transport material, its preparation method and application, to solve the interfacial contact problem between the hole transport material and perovskite in the prior art.

[0008] To achieve the above object, according to the first aspect of this application, a benzocarbazole-based self-assembled hole transport material is provided, and its structural formula is as follows:

[0009]

[0010] Among them, n is 2 to 6; R is selected from C2-C5 heterocyclic groups, C6-C 16 aryl groups, C6-C aryl groups substituted by at least one halogenated group, 16 C6-C aryl groups substituted by at least one C1-C3 haloalkyl group, 16 C2-C6 alkyl groups or C2-C6 alkyl groups substituted by at least one halogenated group;

[0011] and the heteroatom in the C2-C5 heterocyclic group is at least one of N atom, O atom, and S atom; C6-C 16 The aryl group is a monocyclic aryl group or a fused-ring aryl group; C6-C substituted by at least one halogen group 16 In the aryl group substituted by at least one halogen group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; C6-C substituted by at least one C1-C3 haloalkyl group 16 In the C1-C3 haloalkyl group in the aryl group substituted by at least one C1-C3 haloalkyl group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; in the C2-C6 alkyl group substituted by at least one halogen group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I.

[0012] Further, R is selected from the C2-C5 heterocyclic group, phenyl group, C6-C 16 fused-ring aryl group, C6-C substituted by at least one halogen group 10 aryl group, C6-C substituted by at least one halomethyl group 16 aryl group, C2-C4 alkyl group or C2-C4 alkyl group substituted by at least one halogen group;

[0013] and the number of heteroatoms in the C2-C5 heterocyclic group is 1-3; and / or, the C6-C 16 fused-ring aryl group contains 0-2 heteroatoms, and the heteroatom is at least one of N atom, O atom, and S atom; and / or, C6-C substituted by at least one halogen group 10 in the aryl group, the number of halogen atoms is 2-4, and the halogen atom is at least one of F, Cl, Br, and I; and / or, C6-C substituted by at least one halomethyl group 16 in the aryl group, the number of halomethyl groups is 1-2, and in the C6-C aryl group substituted by at least one halomethyl group 16 the number of halogen atoms in the aryl group is 1-3, and the halogen atom is at least one of F, Cl, Br, and I; and / or, the number of halogen atoms in the C2-C4 alkyl group substituted by at least one halogen group is 1-2.

[0014] Further, R is selected from any one of the following C2-C5 heterocyclic groups:

[0015]

[0016] Further, R is selected from any one of the following C6-C 16 fused-ring aryl groups:

[0017]

[0018] Further, R is the following compound:

[0019] Wherein, R1, R2, R3, R4, and R5 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R1, R2, R3, R4, and R5 is one of F, Cl, Br, and I.

[0020] Further, the number of halogen atoms in the C6 - C 10 aryl substituted by at least one halogen group is 2 - 4.

[0021] Further, R is the following compound:

[0022] Wherein, R6, R7, and R8 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R6, R7, and R8 is one of F, Cl, Br, and I.

[0023] Further, R is the following compound:

[0024] Wherein, R9 is any one of F, Cl, Br, and I;

[0025] Further preferably, R is selected from any one of the following compounds:

[0026] Wherein, R2, R3, R4, R6, R7, and R8 are each independently selected from one of F, Cl, Br, and I; R1 and R5 are both H.

[0027] Even more preferably, the benzocarbazole - based self - assembled hole - transporting material of the present application is one of the following compounds:

[0028]

[0029] According to the second aspect of the present application, a preparation method of a benzocarbazole - based self - assembled hole - transporting material is provided, including the following steps:

[0030] S1, under the action of a first catalyst, reacting 10 - bromo - 7H - benzo[c]carbazole with a dihaloalkane to obtain 10 - bromo - 7-(2 - haloalkyl)-7H - benzo[c]carbazole; the reaction route of this first reaction is as follows:

[0031] Wherein, n is 2 - 6, and X is one of F, Cl, Br, and I;

[0032] S2, under the action of a second catalyst, causing 10-bromo-7-(2-halogenated alkyl)-7H-benzo[c]carbazole to undergo a second reaction with the intermediate reaction raw material to obtain a second reaction product; wherein the structural formula of the intermediate reaction raw material is as follows:

[0033] Wherein, R is selected from C2-C5 heterocyclic group, C6-C 16 Aryl, C6~C 16 Aryl, C6-C1-C3 substituted with at least one C1-C3 haloalkyl 16 Aryl, C2-C6 alkyl or C2-C6 alkyl substituted by at least one halo group;

[0034] The heteroatom in the C2-C5 heterocyclic group is at least one of a N atom, an O atom, and a S atom; 16 The aryl group is a monocyclic aryl group or a condensed ring aryl group; the C6-C 16 The number of halogen atoms in the aryl group is 1 to 6, and the halogen atoms are selected from at least one of F, Cl, Br, and I; the C6 to C3 substituted with at least one C1 to C3 haloalkyl 16 The number of halogen atoms in the C1-C3 haloalkyl group in the aryl group is 1-6, and the halogen atoms are selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C2-C6 alkyl group substituted with at least one halo group is 1-6, and the halogen atoms are selected from at least one of F, Cl, Br, and I;

[0035] The reaction scheme of the second reaction is as follows:

[0036]

[0037] S3, the second reaction product undergoes a third reaction with triethyl phosphite to obtain a third reaction product; the reaction route of the third reaction is as follows:

[0038]

[0039] S4, the third reaction product undergoes a fourth reaction with trimethylsilyl bromide to obtain a benzocarbazolyl-based self-assembled hole transport material;

[0040] The reaction scheme of the fourth reaction is as follows:

[0041]

[0042] Furthermore, the first catalyst is a mixture of an alkaline solution and tetrabutylammonium bromide; the alkaline solution is an aqueous solution of an alkali, and the alkali is at least one of potassium hydroxide and sodium hydroxide; the mass concentration of the alkali in the alkaline solution is 30% to 70%.

[0043] Further preferably, the molar ratio of tetrabutylammonium bromide, the base in the base solution, and 10-bromo-7H-benzo[c]carbazole is (1 to 3):(3 to 7):1.

[0044] Further, the second catalyst is a mixture of a carbonate solution and palladium tetrakis(triphenylphosphine); the carbonate solution is an aqueous solution of a carbonate, and the carbonate is at least one of potassium carbonate and sodium carbonate; the mass concentration of the carbonate in the carbonate solution is 30% to 70%.

[0045] Further preferably, the molar ratio of palladium tetrakis(triphenylphosphine), the carbonate in the carbonate solution, and 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole is (0.01 to 0.05):(1 to 3):1.

[0046] Further, the second reaction, the third reaction, and the fourth reaction are carried out in an inert gas atmosphere.

[0047] Further, the reaction medium of the first reaction includes a first solvent; the first solvent is at least one of a haloalkane, tetrahydrofuran, and N,N-dimethylformamide.

[0048] Further, the reaction medium of the second reaction includes a second solvent; the second solvent is at least one of toluene, tetrahydrofuran, and N,N-dimethylformamide.

[0049] Further, the reaction medium of the fourth reaction includes a third solvent; the third solvent is at least one of 1,4-dioxane, tetrahydrofuran, and dichloromethane.

[0050] Further, the reaction raw materials of the fourth reaction further include an alkanol having 1 to 3 carbon atoms.

[0051] Further, the temperature of the first reaction is 40 to 100 °C, preferably 50 to 80 °C, and more preferably 55 to 75 °C; the time of the first reaction is 5 to 20 h, preferably 5 to 15 h, and more preferably 10 to 15 h.

[0052] Further, the temperature of the second reaction is 80 to 120 °C, preferably 90 to 110 °C, and more preferably 100 to 110 °C; the time of the second reaction is 5 to 20 h, preferably 5 to 15 h, and more preferably 10 to 15 h.

[0053] Further, the temperature of the third reaction is 120 to 180 °C, preferably 140 to 180 °C, and more preferably 150 to 170 °C; the time of the third reaction is 10 to 30 h, preferably 10 to 20 h, and more preferably 15 to 20 h.

[0054] Further, in S1, the molar ratio of 10-bromo-7H-benzo[c]carbazole to the dihaloalkane is 1:(1 - 30).

[0055] Further, in S2, the molar ratio of 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole to the intermediate reaction raw material is 1:(1 - 5).

[0056] Further, in S3, the molar ratio of the second reaction product to triethyl phosphite is 1:(3 - 5).

[0057] Further, in S4, the molar ratio of the third reaction product to trimethylsilyl bromide is 1:(1 - 20), preferably 1:(1 - 5).

[0058] Further, in S1, after the first reaction ends, the mixture obtained from the first reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and it is purified by silica gel column chromatography to obtain 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole.

[0059] Further, in S2, after the second reaction ends, the mixture obtained from the second reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and it is purified by silica gel column chromatography to obtain the second reaction product.

[0060] Further, in S3, after the third reaction ends, the mixture obtained from the third reaction is naturally cooled to room temperature, the solvent is removed, and it is purified by silica gel column chromatography to obtain the third reaction product.

[0061] Further, in S4, after the fourth reaction ends, methanol is added to the mixture obtained from the fourth reaction, and then distilled water is added until the solution becomes opaque, stirred for 10 - 15 h, filtered, and the solid substance is washed with water to obtain the benzocarbazole-based self-assembled hole transport material.

[0062] According to the third aspect of the present application, there is provided an application of the benzocarbazole-based self-assembled hole transport material of the first aspect of the present application or the benzocarbazole-based self-assembled hole transport material prepared by the preparation method of the second aspect of the present application in a perovskite solar cell.

[0063] Applying the technical solution in the present application, using a single benzocarbazole group as the core and a phosphonic acid group as the anchoring group, controlling the type of R can effectively improve the wettability between the hole transport material and the perovskite, which is suitable for the preparation of WBG-type PSCs, and is conducive to promoting the growth of a high-quality perovskite film, thereby improving the photoelectric conversion efficiency of the perovskite solar cell. Description of the Drawings

[0064] Figure 1 Schematic diagram of the structure of the perovskite solar cell prepared in the embodiment of the present invention;

[0065] Figure 2 Mechanism diagram of the action of SAMs in the embodiment of the present invention;

[0066] Figure 3 For the benzo[c]carbazole-based self-assembled hole transporting material in Example 1 of the present invention 1 HNMR spectrum;

[0067] Figure 4 For the benzo[c]carbazole-based self-assembled hole transporting material in Example 2 of the present invention 1 HNMR spectrum;

[0068] Figure 5 Electrostatic potential and electron orbital arrangement diagram of the benzo[c]carbazole-based self-assembled hole transporting material in Example 1 of the present invention;

[0069] Figure 6 Electrostatic potential and electron orbital arrangement diagram of the benzo[c]carbazole-based self-assembled hole transporting material in Example 2 of the present invention;

[0070] Figure 7 Ultraviolet-visible absorption spectra of the perovskite of the present invention on the benzo[c]carbazole-based self-assembled hole transporting materials in Example 1 and Example 2 and the 4PADCB hole transporting material respectively;

[0071] Figure 8 External quantum efficiency curves of the organic-inorganic lead halide perovskite solar cells with the benzo[c]carbazole-based self-assembled hole transporting materials in Example 1 and Example 2 and 4PADCB as the hole transporting materials of the present invention;

[0072] Figure 9 J-V curve of the organic-inorganic lead halide perovskite solar cell with the benzo[c]carbazole-based self-assembled hole transporting material in Example 1 of the present invention as the self-assembled hole transporting material. Detailed implementation manners

[0073] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. For those not specified in the embodiments, they shall be carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0074] As described in the background art of the present application, there are problems in the prior art that the interfacial defects between the hole transport material and perovskite in WBG-type PSCs are large, and the surface wettability of the hole transport material is poor. To solve the above problems, in a typical embodiment of the present application, a benzocarbazole-based self-assembled hole transport material is provided, and the structural formula of the benzocarbazole-based self-assembled hole transport material is as follows:

[0075]

[0076] Among them, n is 2 to 6; R is selected from a C2-C5 heterocyclic group, a C6-C 16 aryl group, a C6-C 16 aryl group substituted by at least one halogen group, a C6-C 16 aryl group substituted by at least one C1-C3 haloalkyl group, a C2-C6 alkyl group or a C2-C6 alkyl group substituted by at least one halogen group;

[0077] and the heteroatom in the C2-C5 heterocyclic group is at least one of an N atom, an O atom, and an S atom; the C6-C 16 aryl group is a monocyclic aryl group or a polycyclic aryl group; the number of halogen atoms in the C6-C 16 aryl group substituted by at least one halogen group is 1 to 6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C1-C3 haloalkyl group in the C6-C 16 aryl group substituted by at least one C1-C3 haloalkyl group is 1 to 6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C2-C6 alkyl group substituted by at least one halogen group is 1 to 6, and the halogen atom is selected from at least one of F, Cl, Br, and I.

[0078] The special molecular structure and electronic properties of the carbazole group endow it with good hole-transporting ability. Its asymmetric structure helps to improve the surface wettability of the material, passivate the defects at the perovskite interface, and promote the formation of high-quality perovskite thin films, thereby enhancing the stability and efficiency of perovskite solar cells. The phosphonic acid group has good adhesion and wettability with the interface of transparent electrodes such as ITO, and it can form chemical bonds with the hydroxyl groups or metal ions on the electrode surface, improving the film-forming quality of the material. The introduction of the phosphonic acid group also helps to increase the molecular polarity, facilitating the dissolution of the material in the solvent, and thus improving the uniformity and stability of the thin film. The introduction of the R group further improves the solubility and film-forming property of the material in the solvent, contributing to large-scale production. When n is from 2 to 6, the length of the alkane chain is appropriate, which can ensure good solubility of the hole-transporting material, thereby improving the uniformity and stability of the thin film. In addition, it can provide sufficient steric hindrance to form a more stable chemical adsorption of the material on electrodes such as ITO, and then form a more ordered interfacial layer. Moreover, an appropriate value of n also helps to balance the HOMO energy level of the material, optimize the conformation and spatial arrangement of the molecule, and thus improve the charge transport efficiency between the hole-transporting material and the perovskite layer.

[0079] In some embodiments, R is selected from the group consisting of C2-C5 heterocyclic groups, phenyl groups, C6-C 16 fused polycyclic aryl groups, C6-C 10 aryl groups substituted with at least one halogen group, C6-C 16 aryl groups substituted with at least one halomethyl group, C2-C4 alkyl groups, or C2-C4 alkyl groups substituted with at least one halogen group;

[0080] and the number of heteroatoms in the C2-C5 heterocyclic group is 1-3; and / or, the C6-C 16 fused polycyclic aryl group contains 0-2 heteroatoms, and the heteroatoms are at least one of N atom, O atom, and S atom; and / or, the number of halogen atoms in the C6-C 10 aryl group substituted with at least one halogen group is 2-4, and the halogen atoms are at least one of F, Cl, Br, and I; and / or, the number of halomethyl groups in the C6-C 16 aryl group substituted with at least one halomethyl group is 1-2, and the number of halogen atoms in the C6-C 16 aryl group substituted with at least one halomethyl group is 1-3, and the halogen atoms are at least one of F, Cl, Br, and I; and / or, the number of halogen atoms in the C2-C4 alkyl group substituted with at least one halogen group is 1-2.

[0081] The introduction of the above R group can regulate the HOMO energy level of the material and promote hole extraction. In addition, it can also alleviate the interfacial defects between the hole-transporting material and the perovskite, thereby improving the photoelectric conversion efficiency of PSCs.

[0082] In some embodiments, R is selected from any one of the following C2-C5 heterocyclic groups:

[0083]

[0084] Alternatively, R is selected from any one of the following C6-C 16 polycyclic aryl groups:

[0085]

[0086] Alternatively, R is the following compound:

[0087] Wherein, R1, R2, R3, R4, and R5 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R1, R2, R3, R4, and R5 is one of F, Cl, Br, and I; the number of halogen atoms in the C6-C 10 aryl group substituted by at least one halogen group is 2-4;

[0088] Alternatively, R is the following compound:

[0089] Wherein, R6, R7, and R8 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R6, R7, and R8 is one of F, Cl, Br, and I;

[0090] Alternatively, R is the following compound:

[0091] Wherein, R9 is any one of F, Cl, Br, and I.

[0092] In the present application, "*" represents a chemical bonding site.

[0093] Compared with other types, selecting the above R group helps to alleviate the contact problem between the hole transport layer and the perovskite layer and improve the photoelectric conversion efficiency.

[0094] In some preferred embodiments, R is selected from any one of the following compounds:

[0095] Wherein, R2, R3, R4, R6, R7, and R8 are each independently selected from one of F, Cl, Br, and I; R1 and R5 are both H.

[0096] By selecting the type of R group and controlling it to be a phenyl or tolyl group containing three halogen atoms, on the one hand, the surface tension of the hole transport material can be further enhanced, the surface energy of the material can be increased, thereby improving the spreading property of the perovskite solution on its surface; on the other hand, it helps to promote the directional arrangement of molecules at the interface, form an ordered monolayer film, and optimize the interface matching between the hole transport material and the perovskite layer; on the third hand, it can passivate the defects on the surface of the perovskite layer through its electron adsorption ability, reduce recombination, and thus improve the photoelectric conversion efficiency of the perovskite solar cell.

[0097] In some embodiments, the benzocarbazole-based self-assembled hole transport material of the present application is one of the following compounds:

[0098]

[0099] By selecting the type of R group and introducing a fluorine-containing group, on the one hand, the hole transport material can have good solubility, which is beneficial to the formation of an ordered and efficient self-assembled monolayer film; on the other hand, it can further passivate the interface defects between the hole transport material and the perovskite, and further improve the photoelectric conversion efficiency of PSCs.

[0100] In another typical embodiment of the present application, a preparation method of a benzocarbazole-based self-assembled hole transport material is provided, including the following steps:

[0101] S1, under the action of a first catalyst, 10-bromo-7H-benzo[c]carbazole reacts with a dihaloalkane to undergo a first reaction to obtain 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole; the reaction route of this first reaction is as follows:

[0102] Among them, n is 2-6, and X is one of F, Cl, Br, I;

[0103] S2, under the action of a second catalyst, 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole reacts with an intermediate reaction raw material to undergo a second reaction to obtain a second reaction product; among them, the structural formula of the intermediate reaction raw material is as follows:

[0104] Among them, R is selected from a C2-C5 heterocyclic group, a C6-C 16 aryl group, a C6-C 16 aryl group substituted by at least one halogen group, a C6-C 16 aryl group substituted by at least one C1-C3 haloalkyl group, a C2-C6 alkyl group or a C2-C6 alkyl group substituted by at least one halogen group;

[0105] and the heteroatom in the C2-C5 heterocyclic group is at least one of N atom, O atom, and S atom; C6-C 16 The aryl group is a monocyclic aryl group or a fused-ring aryl group; C6-C substituted by at least one halogen group 16 In the aryl group substituted by at least one halogen group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; C6-C substituted by at least one C1-C3 haloalkyl group 16 In the C1-C3 haloalkyl group in the aryl group substituted by at least one C1-C3 haloalkyl group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; in the C2-C6 alkyl group substituted by at least one halogen group, the number of halogen atoms is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I;

[0106] The reaction route of the second reaction is as follows:

[0107]

[0108] S3. The second reaction product reacts with triethyl phosphite in a third reaction to obtain a third reaction product; the reaction route of the third reaction is as follows:

[0109]

[0110] S4. The third reaction product reacts with trimethylbromosilane in a fourth reaction to obtain a benzocarbazole-based self-assembled hole transport material;

[0111] The reaction route of the fourth reaction is as follows:

[0112]

[0113] This preparation method can not only ensure the high-quality synthesis of the benzocarbazole-based self-assembled hole transport material, but also optimize the electronic, physical and interfacial properties of the material through precise chemical design and reaction control, providing a solid foundation for the high performance and stability of perovskite solar cells.

[0114] In some embodiments, the first catalyst is a mixture of an alkali solution and tetrabutylammonium bromide; the alkali solution is an aqueous solution of an alkali, and the alkali is at least one of potassium hydroxide and sodium hydroxide; the mass concentration of the alkali in the alkali solution is 30%-70%.

[0115] Aqueous solution under alkaline conditions can promote the N-alkylation reaction between 10-bromo-7H-benzo[c]carbazole and dihalogenated alkanes. Potassium hydroxide and sodium hydroxide are both strong bases that can effectively provide the alkaline environment required for the reaction, accelerate the reaction rate, and improve the completion of the reaction. Tetrabutylammonium bromide, as a phase transfer catalyst, can significantly improve the reaction efficiency between the organic phase and the aqueous phase, especially in the reaction of halogenated alkanes with water-soluble compounds, it can play a bridging role, promote the mutual contact of the two reactants, and accelerate the reaction rate.

[0116] In some embodiments, the molar ratio of tetrabutylammonium bromide, the base in the alkaline solution, and 10-bromo-7H-benzo[c]carbazole is (1-3):(3-7):1.

[0117] Controlling the molar ratio of the above components can fully exert the effects of each component and promote the first reaction.

[0118] In some embodiments, the second catalyst is a mixture of a carbonate solution and tetrakis(triphenylphosphine)palladium; the carbonate solution is an aqueous solution of carbonate, and the carbonate is at least one of potassium carbonate and sodium carbonate; the mass concentration of the carbonate in the carbonate solution is 30% to 70%.

[0119] Tetrakis(triphenylphosphine)palladium can promote the coupling of 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole with an aromatic or heterocyclic group to form a second reaction product of the target. Potassium carbonate and sodium carbonate, as alkaline substances, can provide the necessary alkaline conditions to promote the palladium-catalyzed coupling reaction, thereby improving the reaction efficiency. By adjusting the mass concentration of the carbonate solution, the reaction conditions can be precisely controlled to avoid the decomposition of the target product or the increase of side reactions caused by excessive alkalinity. The appropriate base concentration helps to maintain a mild and effective reaction environment to ensure the complete formation of the target molecular structure.

[0120] In some embodiments, the molar ratio of tetrakis(triphenylphosphine)palladium, carbonate in the carbonate solution, and 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole is (0.01-0.05):(1-3):1.

[0121] The molar ratio of the above components is controlled in order to start and accelerate the reaction, and to avoid excessive use of catalysts, which may lead to increased costs and increased probability of side reactions.

[0122] In some embodiments, the second reaction, the third reaction, and the fourth reaction are carried out under an inert gas atmosphere, wherein the inert gas includes at least one of nitrogen, helium, and argon. Carrying out the reaction under inert gas conditions helps to improve the purity of the product.

[0123] In some embodiments, the reaction medium of the first reaction comprises a first solvent; the first solvent is at least one of a halogenated alkane, tetrahydrofuran, and N,N-dimethylformamide. The reaction medium of the second reaction comprises a second solvent; the second solvent is at least one of toluene, tetrahydrofuran, and N,N-dimethylformamide. The reaction medium of the fourth reaction comprises a third solvent; the third solvent is at least one of 1,4-dioxane, tetrahydrofuran, and dichloromethane.

[0124] By adding the above reaction media, a suitable reaction environment can be provided for the reaction, facilitating the mixing and reaction of the reactants, increasing the yield of the target product, and helping to maintain the specificity of the reaction and the purity of the product.

[0125] In some embodiments, the reaction raw materials of the fourth reaction further include an alkanol having 1 to 3 carbon atoms, specifically, it can be methanol, ethanol, propanol, etc.

[0126] The alkanol having 1 to 3 carbon atoms can not only participate in the reaction as a reaction raw material, but also act as a solvent, helping to uniformly disperse the reactants, increasing the reaction efficiency and yield. In addition, adding an alkanol, especially methanol, after the reaction is completed can act as a terminator to quench the remaining active reactants and prevent the unreacted materials from further reacting, thereby avoiding the formation of by-products and increasing the purity of the target product.

[0127] In some embodiments, the temperature of the first reaction is 40 to 100 °C, preferably 50 to 80 °C, more preferably 55 to 75 °C; the time of the first reaction is 5 to 20 h, preferably 5 to 15 h, more preferably 10 to 15 h. The temperature of the second reaction is 80 to 120 °C, preferably 90 to 110 °C, more preferably 100 to 110 °C; the time of the second reaction is 5 to 20 h, preferably 5 to 15 h, more preferably 10 to 15 h. The temperature of the third reaction is 120 to 180 °C, preferably 140 to 180 °C, more preferably 150 to 170 °C; the time of the third reaction is 10 to 30 h, preferably 10 to 20 h, more preferably 15 to 20 h. The fourth reaction can be carried out at room temperature.

[0128] By making the above limitations on the reaction conditions, the reaction efficiency can be improved, the yield can be increased, and it helps to improve the purity of the product.

[0129] In some embodiments, in S1, the molar ratio of 10-bromo-7H-benzo[c]carbazole to the dihaloalkane is 1:(1 - 30); in S2, the molar ratio of 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole to the intermediate reaction raw material is 1:(1 - 5); in S3, the molar ratio of the second reaction product to triethyl phosphite is 1:(3 - 5); in S4, the molar ratio of the third reaction product to trimethylsilyl bromide is 1:(1 - 20), preferably 1:(1 - 5).

[0130] By controlling the molar ratios of the reactants in S1 - S4 within the above ranges, the two reactants can react fully, improving the utilization rate of the reactants.

[0131] To further improve the purity of the product, in some embodiments, in S1, after the first reaction ends, the mixture obtained from the first reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and purified by silica gel column chromatography to obtain 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole. Among them, anhydrous magnesium sulfate can be used for drying, the solvent can be removed by methods such as rotary evaporation, and the eluent for purification by silica gel column chromatography can be a mixed solution of petroleum ether and dichloromethane, and the volume ratio of the two is preferably 3:(0.5 - 1.5). In some embodiments, in S2, after the second reaction ends, the mixture obtained from the second reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and purified by silica gel column chromatography to obtain the second reaction product. Among them, anhydrous magnesium sulfate can also be used for drying, the solvent is removed by rotary evaporation, and the eluent for purification by silica gel column chromatography can be a mixed solution of petroleum ether and dichloromethane, and the volume ratio of the two is preferably 1:(0.5 - 1.5). In some embodiments, in S3, after the third reaction ends, the mixture obtained from the third reaction is naturally cooled to room temperature, the solvent is removed, and purified by silica gel column chromatography to obtain the third reaction product; among them, the solvent can be removed by rotary evaporation, and the eluent for purification by silica gel column chromatography can be a mixed solution of dichloromethane and ethyl acetate, and the volume ratio of the two is preferably 3:(0.5 - 1.5). In some embodiments, in S4, after the fourth reaction ends, methanol is added to the mixture obtained from the fourth reaction, and then distilled water is added until the solution becomes opaque, stirred for 10 - 15 h, filtered, and the solid substance is washed with water to obtain the benzocarbazole-based self-assembled hole transport material.

[0132] In another typical embodiment of the present application, an application of the benzocarbazole-based self-assembled hole transport material in the above embodiment in a perovskite solar cell is provided. The structural schematic diagram of the perovskite solar cell is as Figure 1As shown in the figure, it includes an ITO layer, a hole transport layer, a perovskite light absorption layer, an electron transport layer, an electrode, etc., which are stacked in sequence. Among them, the hole transport layer is formed by the above-mentioned hole transport material. The action mechanism diagram of SAMs is shown in Figure 2 As shown, the linking group in the benzo-carbazole-based self-assembled hole transport material links the anchoring group and the terminal group. The anchoring group is used to form a good bonding effect with the ITO glass, and the terminal group is in contact with the perovskite layer, which can form a stable structure. The perovskite solar cell applying this benzo-carbazole-based self-assembled hole transport material has good photoelectric conversion efficiency.

[0133] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0134]

Benzo-carbazole-based self-assembled hole transport material

[0135] Example 1

[0136] An embodiment of the benzo-carbazole-based self-assembled hole transport material of the present application. The preparation method of the benzo-carbazole-based self-assembled hole transport material in this embodiment is as follows:

[0137] S1. Add Br-BCB (1.2 g, 4.05 mmol), 1,4-dibromoethane (6.98 mL, 81.04 mmol), tetrabutylammonium bromide (TBAB, 0.26 g, 0.81 mmol) and 2.2 mL of 50% potassium hydroxide aqueous solution into a 100 mL reaction tube in sequence; stir and heat up to 60 °C, and react for 12 h; after confirming the reaction is complete by TLC, cool the reaction mixture to room temperature, wash with water, and then extract with dichloromethane. The obtained organic phase is dried with anhydrous magnesium sulfate, and the solvent is removed by distillation under reduced pressure. The first reaction product Br-BCB-C2Br 1.26 g is purified by silica gel column chromatography with petroleum ether / dichloromethane (3:1, v / v) as the eluent, and its yield is 77%; the reaction process is as follows:

[0138]

[0139] S2. In a 100 mL two-necked flask, dissolve Br-BCB-C2Br (1 g, 2.48 mmol) and 4,4,5,5-tetramethyl-2-(4-(trifluoromethyl)phenyl)-1,3,2-dioxaborolane (1.01 g, 3.72 mmol) in 25 mL of toluene, then add 2.2 mL of a 50% aqueous potassium carbonate solution. Evacuate and purge with nitrogen several times, add tetrakis(triphenylphosphine)palladium (Pd(PPh3)4, 0.14 g, 0.124 mmol), heat to 110 °C, reflux with condensation for 12 h. After confirming the completion of the reaction by TLC, cool the reaction mixture to room temperature, wash with water, and then extract with dichloromethane. Dry the obtained organic phase with anhydrous magnesium sulfate, distill off the solvent under reduced pressure, and purify by silica gel column chromatography using petroleum ether / dichloromethane (1:1, v / v) as the eluent to obtain 0.79 g of the second reaction product CF3-BCB-C2Br, with a yield of 69%. The reaction process is as follows:

[0140]

[0141] S3. Dissolve the reactant CF3-BCB-C2Br (0.79 g, 1.69 mmol) in triethyl phosphite (6.8 mL) in a 100 mL reaction tube. Evacuate and purge with nitrogen several times, and reflux at 160 °C in a sand bath for 16 h. After confirming the completion of the reaction by TLC, cool the mixture to room temperature, distill off the solvent (unreacted triethyl phosphite) under reduced pressure, and purify by silica gel column chromatography using petroleum ether / ethyl acetate (3:1, v / v) as the eluent to obtain 0.71 g of the third reaction product CF3-BCB-C2P, with a yield of 80%. The reaction process is as follows:

[0142]

[0143] S4. Dissolve CF3-BCB-C2P (0.5 g, 0.95 mmol) in anhydrous 1,4-dioxane (10 mL) under a nitrogen atmosphere and add trimethylsilyl bromide (1.46 g, 9.6 mmol) dropwise. After reacting at room temperature for 24 h, add 5 mL of methanol and continue stirring for 3 h. After rotary evaporation to remove some of the solvent, add 5 mL of methanol, and then dropwise add distilled water until the solution becomes opaque. Stir for 12 h. Filter out the product, wash with water, and dry to obtain 0.28 g of the white solid CF3-BCB-C2PA, with a yield of 63%. The reaction process is as follows:

[0144]

[0145] Its 1 1H NMR spectrum is as Figure 3 shown 11H NMR (500 MHz, CDCl3): δ 8.80 (d, J = 8.3 Hz, 1H), 8.67 (s, 1H), 8.06 (d, J = 8.1 Hz, 1H), 7.99 (d, J = 8.9 Hz, 1H), 7.79 (d, J = 8.3, 6.8, 1.4 Hz, 1H), 7.70 (d, J = 8.9 Hz, 1H), 7.64 (d, J = 1.8 Hz, 2H), 7.59–7.50 (m, 1H), 7.44–7.33 (m, 2H), 4.88 (t, J = 7.4 Hz, 2H), 3.77 (t, J = 7.3 Hz, 2H).

[0146] Example 2

[0147] An example of the benzocarbazole-based self-assembled hole transport material of the present application. The preparation method of the benzocarbazole-based self-assembled hole transport material in this example is as follows:

[0148] S1. In a 100 mL reaction tube, successively add Br-BCB (1.2 g, 4.05 mmol), 1,4-dibromoethane (6.98 mL, 81.04 mmol), tetrabutylammonium bromide (0.26 g, 0.81 mmol), and 2.2 mL of a 50% by mass aqueous potassium hydroxide solution; heat to 60 °C and react for 12 h; after confirming the reaction is complete by TLC, cool the reaction mixture to room temperature, wash with water, then extract with dichloromethane. The obtained organic phase is dried over anhydrous magnesium sulfate and then the solvent is removed by distillation under reduced pressure. The first reaction product Br-BCB-C2Br, 1.26 g, is purified by silica gel column chromatography using petroleum ether / dichloromethane (3:1, v / v) as the eluent, and its yield is 77%; the reaction process is as follows:

[0149]

[0150] S2. In a 100 mL two-necked flask, dissolve Br-BCB-C2Br (1 g, 2.48 mmol) and 4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane (0.96 g, 3.72 mmol) in 25 mL of toluene, then add it to 2.2 mL of a 50% by mass aqueous potassium carbonate solution; evacuate and purge with nitrogen several times, add tetrakis(triphenylphosphine)palladium (0.14 g, 0.124 mmol), heat to 110 °C, carry out reflux condensation, and react for 12 h; after confirming the reaction is complete by TLC, cool the reaction mixture to room temperature, wash with water, then extract with dichloromethane. The obtained organic phase is dried over anhydrous magnesium sulfate and then the solvent is removed by distillation under reduced pressure. The second reaction product 3F-BCB-C2Br, 0.73 g, is purified by silica gel column chromatography using petroleum ether / dichloromethane (1:1, v / v) as the eluent, and its yield is 65%; the reaction process is as follows:

[0151]

[0152] S3. In a 100 mL reaction tube, dissolve the reactant 3F-BCB-C2Br (0.7 g, 1.54 mmol) in triethyl phosphite (8.6 mL). Evacuate and purge with nitrogen several times. Reflux the reaction mixture at 160 °C in a sand bath for 16 h. After confirming the completion of the reaction by TLC, cool the mixture to room temperature and distill off the solvent under reduced pressure. Purify the product by silica gel column chromatography using a mixture of petroleum ether / ethyl acetate (3:1, v / v) as the eluent to obtain 0.58 g of the third reaction product 3F-BCB-C2P as a syrup. The yield is 74%. The reaction process is as follows:

[0153]

[0154] S4. Under a nitrogen atmosphere, dissolve 3F-BCB-C2P (0.4 g, 0.78 mmol) in anhydrous 1,4-dioxane (10 mL) and add trimethylsilyl bromide (1.2 g, 7.82 mmol) dropwise. After reacting at room temperature for 24 h, add 5 mL of methanol and continue stirring for 3 h. After rotary evaporation to remove some of the solvent, add 5 mL of methanol, and then add distilled water dropwise until the solution becomes opaque. Stir for 12 h. Filter out the product, wash it with water, and dry it to obtain 0.23 g of the white fourth reaction product 3F-BCB-C2PA. The yield is 75%. The reaction process is as follows:

[0155]

[0156] Its 1 1H NMR spectrum is as Figure 4 shown below. 1 1H NMR (500 MHz, CDCl3): δ 8.84 (d, J = 8.3 Hz, 1H), 8.80 (d, J = 1.7 Hz, 1H), 8.06 (d, J = 8.1 Hz, 1H), 7.99 (d, J = 8.9 Hz, 1H), 7.91 (d, J = 8.0 Hz, 2H), 7.84–7.74 (m, 4H), 7.72 (d, J = 8.9 Hz, 1H), 7.68 (d, J = 8.5 Hz, 1H), 7.55 (t, J = 7.5 Hz, 1H), 4.90 (t, J = 7.4 Hz, 2H), 3.78 (t, J = 7.4 Hz, 2H).

[0157]

Perovskite Solar Cell

[0158] Example 3

[0159] An embodiment of the perovskite solar cell of the present application. In this embodiment, the perovskite solar cell includes a substrate, a hole transport layer, a perovskite layer, an electron transport layer, and a top electrode stacked in sequence. Among them, the material of the hole transport layer is the benzocarbazole-based self-assembled hole transport material prepared in Example 1. The perovskite solar cell of this embodiment is, from bottom to top, an ITO glass substrate / hole transport layer / perovskite layer / electron transport layer (C 60 ) / hole blocking layer (BCP) / Ag electrode; the preparation method is as follows:

[0160] Clean the ITO glass substrate with glass cleaning solution, deionized water, acetone, and isopropanol for 15 minutes in sequence, and then blow dry with dry compressed air; treat the cleaned ITO glass with ultraviolet ozone for 15 minutes to improve wettability; dissolve CF3-BCB-C2PA in absolute ethanol to prepare a solution with a concentration of 0.5 mg / mL, and spin-coat it on the ITO substrate at 3000 rpm for 30 s to prepare the hole transport layer; filter the perovskite solution stirred overnight in the glove box through a 0.22 μm polytetrafluoroethylene (PTFE) membrane, and use ethyl acetate as an antisolvent to deposit the perovskite film in the glove box. After annealing at 100 °C for 30 minutes, under high vacuum (less than 10 -5 Pa) conditions, deposit 26 nm thick C 60 and 6 nm thick BCP by thermal evaporation in sequence; finally, evaporate a 100 nm thick Ag electrode onto the BCP using a 0.12 cm 2 metal mask to obtain the perovskite solar cell. The champion efficiency of the perovskite solar cell of this embodiment under one standard sunlight in a nitrogen-protected room temperature environment is 19.11%.

[0161] Example 4

[0162] An embodiment of the perovskite solar cell of the present application. The difference between the preparation method of the perovskite solar cell of this embodiment and that of Example 3 is only that the concentration of CF3-BCB-C2PA in the solution formed with absolute ethanol is different, which is 0.2 mg / mL. The champion efficiency of this perovskite solar cell under one standard sunlight in a nitrogen-protected room temperature environment is 19.45%.

[0163] Example 5

[0164] An embodiment of the perovskite solar cell of the present application. The structure of the perovskite solar cell of this embodiment is the same as that of Example 3; the preparation method is as follows:

[0165] The ITO glass substrate was cleaned successively with glass cleaning solution, deionized water, acetone and isopropyl alcohol for 15 min, and then dried with dry compressed air; the cleaned ITO glass was treated with ultraviolet ozone for 15 min to improve wettability; 3F-BCB-C2PA was dissolved in absolute ethanol to prepare a solution with a concentration of 0.5 mg / mL, and spin-coated on the ITO substrate at 3000 rpm for 30 s to prepare a hole transport layer; the perovskite solution stirred overnight in a glove box was filtered through a 0.22-μm polytetrafluoroethylene (PTFE) membrane, and ethyl acetate was used as an antisolvent to deposit a perovskite film in the glove box. After annealing at 100 °C for 30 minutes, under high vacuum (less than 10 -5 Pa), 26-nm-thick C 60 and 6-nm-thick BCP were successively deposited by thermal evaporation; finally, a 100-nm-thick Ag electrode was evaporated onto the BCP using a 0.12-cm 2 metal mask to obtain the perovskite solar cell. The champion efficiency of the perovskite solar cell described in this example under one standard sunlight at room temperature under nitrogen protection was 18.65%.

[0166] Example 6

[0167] An embodiment of the perovskite solar cell described in this application. The difference between the preparation method of the perovskite solar cell described in this example and that of Example 5 is only that the concentration of 3F-BCB-C2PA in the solution formed with absolute ethanol is 0.2 mg / mL. The champion efficiency of the perovskite solar cell described in this example under one standard sunlight at room temperature under nitrogen protection was 19.25%.

[0168] Figures 5 - 6 They are respectively the electrostatic potential and electron orbital arrangement diagrams of the compound CF3-BCB-C2PA in Example 1 and the compound 3F-BCB-C2PA in Example 2 of the present invention. As can be seen from the figure, the electrostatic dipole moment μ of CF3-BCB-C2PA is 4.82 D, the HOMO is -5.78 eV, and the LUMO is -1.33 eV. The electrostatic dipole moment μ of 3F-BCB-C2PA is 4.83 D, the HOMO is -5.48 eV, and the LUMO is -1.35 eV.

[0169] Figure 7 They are the ultraviolet-visible absorption spectra of the perovskite in Example 1 and Example 2 of the present invention on the benzocarbazole-based self-assembled hole transport material and the 4PADCB hole transport material respectively. As can be seen from the figure, compared with 4PADCB, the ability of the benzocarbazole-based self-assembled hole transport material in Examples 1-2 to absorb ultraviolet-visible light is stronger.

[0170] Figure 8External quantum efficiency curve graphs obtained by measuring the EQE spectra using the QE measurement system (QE-R, EnliTech) for the organic-inorganic lead halide perovskite solar cells with the benzocarbazole-based self-assembled hole transport material in Example 1 and Example 2 of the present invention and 4PADCB as the hole transport material (before testing, the light intensity at each wavelength was calibrated with a standard silicon solar cell). As can be seen from the figure, the external quantum efficiency of the perovskite solar cells made of the benzocarbazole-based self-assembled hole transport material in the examples of the present invention is significantly higher.

[0171] Figure 9 For the organic-inorganic lead halide perovskite solar cell with the benzocarbazole-based self-assembled hole transport material as the self-assembled hole transport material in Example 1 of the present invention, using the EnliTech SS-X5-3A solar simulator, under the simulated illumination conditions of 100 mW / cm 2 , AM 1.5G, the current density vs. voltage curve (J-V curve) of the electronic device in the space charge limited current (SCLC) analysis was measured. As can be seen from the figure, its photoelectric conversion efficiency is high.

[0172] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A benzocarbazole-based self-assembled hole transport material, characterized in that The structural formula of the benzocarbazole-based self-assembled hole transport material is as follows: Among them, n is 2 to 6; R is selected from a C2-C5 heterocyclic group, a C6-C 16 aryl, a C6-C aryl substituted by at least one halogen group 16 aryl, a C6-C aryl substituted by at least one C1-C3 haloalkyl 16 aryl, a C2-C6 alkyl or a C2-C6 alkyl substituted by at least one halogen group; and the heteroatom in the C2-C5 heterocyclic group is at least one of N atom, O atom, and S atom; the C6-C 16 aryl is a monocyclic aryl or a fused-ring aryl; the number of halogen atoms in the C6-C 16 aryl substituted by at least one halogen group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C1-C3 haloalkyl group in the C6-C 16 aryl substituted by at least one C1-C3 haloalkyl group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C2-C6 alkyl group substituted by at least one halogen group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I.

2. The benzocarbazole-based self-assembled hole transport material according to claim 1, wherein R is selected from the group consisting of the C2-C5 heterocyclic group, phenyl, C6-C 16 condensed polycyclic aryl group, C6-C aryl group substituted with at least one halogen group 10 aryl group, C6-C aryl group substituted with at least one halomethyl group 16 aryl group, C2-C4 alkyl group or C2-C4 alkyl group substituted with at least one halogen group; and the number of heteroatoms in the C2-C5 heterocyclic group is 1-3; and / or, the C6-C 16 The fused polycyclic aryl group contains 0-2 heteroatoms, and the heteroatoms are at least one of N atom, O atom, and S atom; and / or, the number of halogen atoms in the C6-C 10 aryl group substituted by at least one halogen group is 2-4, and the halogen atom is at least one of F, Cl, Br, and I; and / or, the number of halomethyl groups in the C6-C 16 aryl group substituted by at least one halomethyl group is 1-2, and the number of halogen atoms in the C6-C 16 aryl group substituted by at least one halomethyl group is 1-3, and the halogen atom is at least one of F, Cl, Br, and I; and / or, the number of halogen atoms in the C2-C4 alkyl group substituted by at least one halogen group is 1-2.

3. The benzocarbazole-based self-assembled hole transport material according to claim 2, wherein The R is selected from any one of the following C2-C5 heterocyclic groups: and / or said R is selected from any one of the following C6-C 16 condensed polycyclic aryl groups: and / or The R is the following compound: wherein, R1, R2, R3, R4, and R5 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R1, R2, R3, R4, and R5 is one of F, Cl, Br, and I; and / or The C6-C 10 aryl substituted by at least one halogen group has 2 to 4 halogen atoms; and / or The R is the following compound: wherein, R6, R7, and R8 are each independently selected from one of H, F, Cl, Br, and I, and at least one of the R6, R7, and R8 is one of F, Cl, Br, and I; and / or The R is the following compound: Among them, R9 is any one of F, Cl, Br, and I; Preferably, the R is selected from any one of the following compounds: Among them, each of R2, R3, R4, R6, R7, and R8 is independently selected from one of F, Cl, Br, and I; both R1 and R5 are H.

4. The benzocarbazole-based self-assembled hole transport material according to claim 3, wherein The benzocarbazole-based self-assembled hole transport material is one of the following compounds:

5. A preparation method of a benzocarbazole-based self-assembled hole transport material, characterized in that, Comprising the following steps: S1, under the action of a first catalyst, 10-bromo-7H-benzo[c]carbazole reacts with a dihaloalkane to obtain 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole. The reaction route of the first reaction is as follows: wherein, n is 2 to 6, and X is one of F, Cl, Br, and I; S2, under the action of a second catalyst, the 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole reacts with an intermediate reaction raw material to obtain a second reaction product. The structural formula of the intermediate reaction raw material is as follows: Among them, R is selected from a C2-C5 heterocyclic group, a C6-C 16 aryl group, a C6-C aryl group substituted by at least one halogenated group, 16 a C6-C aryl group substituted by at least one C1-C3 haloalkyl group, 16 an aryl group, a C2-C6 alkyl group or a C2-C6 alkyl group substituted by at least one halogenated group; and the heteroatom in the C2-C5 heterocyclic group is at least one of N atom, O atom, and S atom; the C6-C 16 aryl is a monocyclic aryl or a fused-ring aryl; the number of halogen atoms in the C6-C 16 aryl substituted by at least one halogen group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C1-C3 haloalkyl group in the C6-C 16 aryl substituted by at least one C1-C3 haloalkyl group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; the number of halogen atoms in the C2-C6 alkyl group substituted by at least one halogen group is 1-6, and the halogen atom is selected from at least one of F, Cl, Br, and I; The reaction route of the second reaction is as follows: S3, the second reaction product reacts with triethyl phosphite to obtain a third reaction product. The reaction route of the third reaction is as follows: S4, the third reaction product reacts with trimethylsilyl bromide to obtain the benzocarbazole-based self-assembled hole transport material. The reaction route of the fourth reaction is as follows:

6. The preparation method according to claim 5, wherein Comprising at least one of the following features: (1) The first catalyst is a mixture of an alkali solution and tetrabutylammonium bromide; the alkali solution is an aqueous solution of an alkali, and the alkali is at least one of potassium hydroxide and sodium hydroxide; the mass concentration of the alkali in the alkali solution is 30% to 70%; (2) The second catalyst is a mixture of a carbonate solution and tetrakis(triphenylphosphine)palladium; the carbonate solution is an aqueous solution of a carbonate, and the carbonate is at least one of potassium carbonate and sodium carbonate; the mass concentration of the carbonate in the carbonate solution is 30% to 70%; (3) The second reaction, the third reaction, and the fourth reaction are carried out in an inert gas atmosphere; (4) The reaction medium of the first reaction includes a first solvent; the first solvent is at least one of a haloalkane, tetrahydrofuran, and N,N-dimethylformamide; (5) The reaction medium of the second reaction includes a second solvent; the second solvent is at least one of toluene, tetrahydrofuran, and N,N-dimethylformamide; (6) The reaction medium of the fourth reaction includes a third solvent; the third solvent is at least one of 1,4-dioxane, tetrahydrofuran, and dichloromethane; (7) The reaction raw material of the fourth reaction includes an alkanol having 1 to 3 carbon atoms; (8) The temperature of the first reaction is 40 to 100 °C, and the time of the first reaction is 5 to 20 h; (9) The temperature of the second reaction is 80 to 120 °C, and the time of the second reaction is 5 to 20 h; (10) The temperature of the third reaction is 120 to 180 °C, and the time of the third reaction is 10 to 30 h.

7. The preparation method according to claim 6, characterized in that, Comprising at least one of the following features: (1) The first catalyst is a mixture of an alkali solution and tetrabutylammonium bromide, and the molar ratio of tetrabutylammonium bromide, the alkali in the alkali solution, and 10-bromo-7H-benzo[c]carbazole is (1 to 3):(3 to 7):1; (2) The second catalyst is a mixture of a carbonate solution and tetrakis(triphenylphosphine)palladium; the molar ratio of tetrakis(triphenylphosphine)palladium, the carbonate in the carbonate solution, and 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole is (0.01 to 0.05):(1 to 3):1; (3) The temperature of the first reaction is 50 to 80 °C, and the time of the first reaction is 5 to 15 h; (4) The temperature of the second reaction is 90 to 110 °C, and the time of the second reaction is 5 to 15 h; (5) The temperature of the third reaction is 150 to 170 °C, and the time of the third reaction is 10 to 20 h.

8. The preparation method according to claim 5, characterized in that, Comprising at least one of the following features: (1) In the S1, the molar ratio of 10-bromo-7H-benzo[c]carbazole to the dihaloalkane is 1:(1 to 30); (2) In the S2, the molar ratio of 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole to the intermediate reaction raw material is 1:(1 to 5); (3) In the S3, the molar ratio of the second reaction product to triethyl phosphite is 1:(3 to 5); (4) In the S4, the molar ratio of the third reaction product to trimethylsilyl bromide is 1:(1 to 20).

9. The preparation method according to claim 5, characterized in that, Comprising at least one of the following features: (1) In the S1, after the first reaction ends, the mixture obtained from the first reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and purified by silica gel column chromatography to obtain 10-bromo-7-(2-haloalkyl)-7H-benzo[c]carbazole; (2) In the S2, after the second reaction ends, the mixture obtained from the second reaction is naturally cooled to room temperature, washed with water, extracted with dichloromethane, the obtained organic phase is dried, the solvent is removed, and purified by silica gel column chromatography to obtain the second reaction product; (3) In the S3, after the third reaction ends, the mixture obtained from the third reaction is naturally cooled to room temperature, the solvent is removed, and purified by silica gel column chromatography to obtain the third reaction product; (4) In the S4, after the fourth reaction ends, methanol is added to the mixture obtained from the fourth reaction, and then distilled water is added until the solution becomes opaque, stirred for 10 to 15 h, filtered, and the solid substance is washed with water to obtain the benzocarbazole-based self-assembled hole transport material.

10. Application of a benzocarbazole-based self-assembled hole transport material in a perovskite solar cell, characterized in that, The benzocarbazole-based self-assembled hole transport material is the benzocarbazole-based self-assembled hole transport material according to any one of claims 1 to 4 or the benzocarbazole-based self-assembled hole transport material prepared by the preparation method according to any one of claims 5 to 9.

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