Hole transport material and preparation method thereof, and perovskite solar cell and preparation method thereof

Abstract

The invention relates to the technical field of perovskite cells, provides a hole transport material and a preparation method thereof, and a perovskite solar cell and a preparation method thereof, and at least can maintain the stability of small molecules HTMs without doping any additive. The structure of the hole transport material is as shown in formula I: # imgabs0 #, R is selected from one of the following structural formulae II to IV: # imgabs1 # imgabs2 #

Description

Technical Field

[0001] This application relates to the technical field of perovskite solar cells, and particularly to a hole transport material and its preparation method, and a perovskite solar cell and its preparation method. Background Art

[0002] Perovskite solar cells (PSCs) are devices that use perovskite-type organometallic halide semiconductors as light-absorbing materials to directly convert light energy into electrical energy through the photovoltaic effect. The structure of perovskite solar cells mainly includes components such as a conductive substrate, an electron transport layer (ETL), a perovskite layer, a hole transport layer (HTL), and a metal electrode. Among them, the hole transport layer plays a crucial role in hole extraction and transport, suppressing carrier recombination, and improving the crystallization and film formation of perovskite materials. Therefore, continuously developing hole transport materials (HTMs) with excellent film-forming properties, solvent resistance, thermal stability, hole mobility, and energy levels matching those of perovskite materials is a key factor in preparing efficient and stable perovskite solar cells.

[0003] Currently, HTMs in perovskite solar cells are mainly divided into three categories: inorganic hole transport materials, organic small molecule hole transport materials, and organic polymer hole transport materials. Small molecule HTMs have a definite structure and molecular weight. According to the spatial structure, they can be roughly divided into three categories: linear structure, spiro structure, and star structure. They can also be divided into dithienopyrrole type, triphenylamine type, carbazole type, bifluorene type, thiophene type, etc. according to the different groups contained in the molecular structure. Small molecule HTMs have become the most common type of HTM in perovskite solar cells due to their advantages such as a wide variety of synthesized products, adjustable properties, high purity, and easy solution processing.

[0004] However, due to the rigid structure of small molecule HTMs, they have low tolerance to perovskite precursor solutions, are morphologically unstable under external stimuli, and many small molecule HTMs need to add dopants, which also pose obstacles to the large-scale commercialization of PSCs. Summary of the Invention

[0005] The embodiments of this application provide a hole transport material and its preparation method, and a perovskite solar cell and its preparation method, which can at least maintain the stability of small molecule HTMs without doping any additives.

[0006] According to some embodiments of this application, on the one hand, the embodiments of this application provide a hole transport material with a structure as shown in Formula I:

[0007]

[0008] Wherein, R is selected from one of the following structural formulas II to IV:

[0009]

[0010] According to some embodiments of the present application, the embodiments of the present application also provide a method for preparing a hole transport material, comprising the following steps: performing a first reaction on 9,9-dimethyl-9,10-dihydroacridine and 4-bromothioanisole to prepare a first intermediate product; performing a second reaction on the first intermediate product and N-bromosuccinimide to prepare a second intermediate product; performing a third reaction on the second intermediate product and a boric acid pinacol ester of R to prepare a hole transport material;

[0011] The structure of the first intermediate product is shown in Formula V:

[0012]

[0013] The structure of the second intermediate product is shown in Formula VI:

[0014]

[0015] The structure of the boric acid pinacol ester of R is selected from one of the following formulas VII to IX:

[0016]

[0017] In some embodiments, the step of the first reaction includes: dissolving 9,9-dimethyl-9,10-dihydroacridine, 4-bromothioanisole, sodium tert-butoxide, bis(dibenzylacetone)palladium and tri-tert-butylphosphine in a molar ratio of 1:(1.1-1.3):(0.9-1.1):(0.04-0.06):(0.2-0.22) in toluene, reacting at 120°C for 12 hours and then cooling to room temperature, extracting the organic phase with saturated sodium chloride solution and dichloromethane, drying with anhydrous magnesium sulfate, filtering, distilling under reduced pressure, and purifying by column chromatography to obtain a first intermediate product.

[0018] In some embodiments, the eluent for column chromatography is petroleum ether and dichloromethane in a volume ratio of 6:1.

[0019] In some embodiments, the second reaction step includes: dissolving the first intermediate product and N-bromosuccinimide in tetrahydrofuran at a molar ratio of 1:(2 to 2.3), reacting at 0°C for 12 hours, quenching the reaction with water, extracting the organic phase with dichloromethane, drying with anhydrous magnesium sulfate, filtering, and distilling under reduced pressure, and purifying by column chromatography to obtain a second intermediate product.

[0020] In some embodiments, the eluent for column chromatography is a mixture of petroleum ether and dichloromethane with a volume ratio of 10:1.

[0021] In some embodiments, the steps of the third reaction include: dissolving a second intermediate product, pinacol borate of R, tetrakis(triphenylphosphine)palladium, and potassium carbonate with a molar ratio of 1:(2 - 2.5):(0.04 - 0.06):(5 - 7) in toluene, ethyl acetate, and water (volume ratio 2:1:1), reacting at 85 °C for 6 hours, cooling to room temperature, extracting with dichloromethane, drying with anhydrous magnesium sulfate, filtering, distilling under reduced pressure, and obtaining the hole transport material after purification by column chromatography.

[0022] In some embodiments, the eluent for column chromatography is a mixture of petroleum ether and dichloromethane with a volume ratio of 4:1.

[0023] According to some embodiments of the present application, on the other hand, the present application embodiments also provide a perovskite solar cell, which is composed of a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes the hole transport material in the above embodiments, or is made of the hole transport material prepared by using the preparation method in the above embodiments.

[0024] According to some embodiments of the present application, on the other hand, an embodiment of the present application further provides a method for preparing a perovskite battery, including: Cleaning step: ultrasonically clean the transparent conductive substrate with deionized water, acetone, and ethanol in sequence for 15-20 minutes, dry the transparent conductive substrate, then perform oxygen plasma treatment for 10-15 minutes, and then transfer the transparent conductive substrate to a nitrogen glove box; Prepare the hole transport layer: weigh 3-15 mg of the hole transport material as described in the above embodiments, or the hole transport material prepared by the preparation method of the above embodiments, dissolve it in 1 mL of chlorobenzene solution, take an appropriate amount of the mixed solution and drop it onto the transparent conductive substrate, spin-coat it at a speed of 4000-5000 rpm for 20-30 s, and then anneal it at 90-100 °C for 10 min; Prepare the perovskite absorption layer: cool the transparent conductive substrate with the hole transport layer to room temperature, preheat it at 130-140 °C for 3-5 min, take 50 μL of perovskite solution and spread it on the surface of the hole transport layer, spin-coat it at a speed of 3000-5000 rpm for 20-30 s, and then anneal it at 90-100 °C for 10 min, wherein the solute of the perovskite solution is 3-bromo-benzylammonium iodide or 3-chloro-benzylammonium iodide, methylammonium chloride, and lead iodide, and the solvent is N,N-dimethylformamide and dimethyl sulfoxide; Prepare the electron transport layer: cool the transparent conductive substrate with the perovskite absorption layer to room temperature, take 40 μL of a solution of (6,6)-phenyl-C61-butyric acid methyl ester with a concentration of 15 mg / mL, spread the (6,6)-phenyl-C61-butyric acid methyl ester solution on the perovskite absorption layer, spin-coat it at a speed of 1000-2000 rpm for 30-50 s, and then anneal it at 70-80 °C for 10 min; Prepare the electrode: place the transparent conductive substrate with the electron transport layer in a vacuum evaporation chamber, and evaporate at least one of metal chromium or gold on the electron transport layer.

[0025] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0026] The hole-transporting materials provided by the embodiments of the present application introduce thiophene groups into acridine groups, and SMe-Ac-1, SMe-Ac-2, and SMe-Ac-3 are designed and synthesized. The groups containing multiple sulfur atoms in the molecule endow the HTMs with increased intra- and / or intermolecular interactions, appropriate energy levels, and enhanced buried interface interactions with quasi-two-dimensional layered perovskites, resulting in good mobilities of the hole-transporting materials, which are beneficial to the extraction and transport of holes, HOMO energy levels that match the perovskite and are relatively deep, and high decomposition temperatures, having good thermal stability. SMe-Ac-1, SMe-Ac-2, and SMe-Ac-3 all have good solubility in organic solvents, good film-forming properties, good wettability with perovskite precursor solvents, and are helpful for the crystallization and film formation of perovskites. In addition, the hole-transporting materials provided by the embodiments of the present application have low raw material costs, simple preparation processes, are suitable for industrial production, can be used in inverted quasi-two-dimensional perovskite solar cells without doping any additives, and have repeatability, having good application prospects. Description of the Drawings

[0027] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Unless otherwise stated, the figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 1H NMR spectrum corresponding to the hole-transporting material SMe-Ac-1 provided by the embodiment of the present application;

[0029] Figure 2 1H NMR spectrum corresponding to the hole-transporting material SMe-Ac-2 provided by the embodiment of the present application;

[0030] Figure 3 1H NMR spectrum corresponding to the hole-transporting material SMe-Ac-3 provided by the embodiment of the present application;

[0031] Figure 4 Schematic structural diagram of a perovskite battery provided by the embodiment of the present application. Detailed Embodiments

[0032] As is known from the background art, due to the rigid structure of small molecule HTMs, they have low tolerance to perovskite precursor solutions, are morphologically unstable under external stimuli, and many small molecule HTMs require the addition of dopants, which also pose obstacles to the large-scale commercialization of PSCs.

[0033] For doped-free HTMs containing sulfur functional groups, in order to obtain excellent PSCs, doped-free HTMs usually have excellent hole transport rates. Introducing sulfur functional groups into HTMs can improve the planarity and conductivity of the molecules. In addition, sulfur can coordinate with Pb 2+ atoms and passivate defects at the surface and grain boundaries. The two most commonly used sulfur functional groups are thiophene and methylthio groups.

[0034] The embodiments of the present application provide a hole transport material, a preparation method thereof, a perovskite solar cell, and a preparation method thereof, which can at least maintain the stability of small molecule HTMs without doping any additives.

[0035] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary-secondary relationship of the indicated technical features.

[0036] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: the existence of A, the simultaneous existence of A and B, and the existence of B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0038] The following will elaborate on the embodiments of the present application in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are proposed for the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0039] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a hole transport material with a structure as shown in Formula I:

[0040]

[0041] Among them, R is selected from one of the following structural formulas II to IV:

[0042]

[0043] Specifically, the hole transporting materials provided by the embodiments of the present application include SMe-Ac-1, SMe-Ac-2, and SMe-Ac-3:

[0044]

[0045] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum diagram corresponding to the hole transporting material SMe-Ac-1 provided by the embodiments of the present application; Figure 2 It is the nuclear magnetic resonance hydrogen spectrum diagram corresponding to the hole transporting material SMe-Ac-2 provided by the embodiments of the present application; Figure 3 It is the nuclear magnetic resonance hydrogen spectrum diagram corresponding to the hole transporting material SMe-Ac-3 provided by the embodiments of the present application.

[0046] For the hole transporting materials provided by the embodiments of the present application, thiophene groups are introduced into acridine groups to design and synthesize SMe-Ac-1, SMe-Ac-2, and SMe-Ac-3. The groups containing multiple sulfur atoms in the molecules endow the HTMs with increased intra- and / or intermolecular interactions, appropriate energy levels, and enhanced buried interface interactions with quasi-two-dimensional layered perovskites (Ruddlesden-Popper, RP perovskites), resulting in better mobility of the hole transporting materials, which is beneficial to the extraction and transport of holes, a deeper HOMO (Highest Occupied Molecular Orbital) energy level matching the perovskite, and a higher decomposition temperature, having good thermal stability. SMe-Ac-1, SMe-Ac-2, and SMe-Ac-3 have good solubility in organic solvents such as dimethyl sulfoxide, N,N'-dimethylformamide, toluene, chlorobenzene, and dichloromethane. At the same time, they have good film-forming properties and good wettability with the perovskite precursor solvent, which is helpful for the crystallization and film formation of perovskite. In addition, for the hole transporting materials provided by the embodiments of the present application, the raw material cost is low, the preparation process is simple, it is suitable for industrial production, can be used in inverted quasi-two-dimensional perovskite solar cells without doping any additives, and has repeatability, having good application prospects.

[0047] According to some embodiments of the present application, the second aspect of the embodiments of the present application further provides a preparation method of a hole transporting material, including the following steps:

[0048] S11: 9,9-dimethyl-9,10-dihydroacridine is subjected to a first reaction with 4-bromothioanisole to prepare a first intermediate product. The structure of the first intermediate product is shown in Formula V:

[0049]

[0050] The reaction equation for the first reaction is as follows:

[0051]

[0052] In some embodiments, the first reaction step includes: dissolving 9,9-dimethyl-9,10-dihydroacridine, 4-bromothioanisole, sodium tert-butoxide, bis(dibenzylacetone)palladium and tri-tert-butylphosphine in a molar ratio of 1:(1.1-1.3):(0.9-1.1):(0.04-0.06):(0.2-0.22) in toluene, reacting at 120°C for 12 hours and then cooling to room temperature, extracting the organic phase with saturated sodium chloride solution and dichloromethane, drying with anhydrous magnesium sulfate, filtering, distilling under reduced pressure, and purifying by column chromatography to obtain a first intermediate product.

[0053] In some embodiments, the eluent for column chromatography is petroleum ether and dichloromethane in a volume ratio of 6:1.

[0054] S12: The first intermediate product is subjected to a second reaction with N-bromosuccinimide to prepare a second intermediate product, the structure of which is as shown in Formula VI:

[0055]

[0056] The reaction equation for the second reaction is as follows:

[0057]

[0058] In some embodiments, the second reaction step includes: dissolving the first intermediate product and N-bromosuccinimide in tetrahydrofuran at a molar ratio of 1:(2 to 2.3), reacting at 0°C for 12 hours, quenching the reaction with water, extracting the organic phase with dichloromethane, drying with anhydrous magnesium sulfate, filtering, and distilling under reduced pressure, and purifying by column chromatography to obtain a second intermediate product.

[0059] In some embodiments, the eluent for column chromatography is petroleum ether and dichloromethane in a volume ratio of 10:1.

[0060] S13: performing a third reaction on the second intermediate product and the boric acid pinacol ester of R to prepare a hole transport material.

[0061] The structural formula of the boric acid pinacol ester of R is:

[0062] When, the prepared hole transporting material is SMe-Ac-1;

[0063] The reaction formula of the third reaction is as follows:

[0064]

[0065] The structural formula of the pinacol borate of R is:

[0066] When, the prepared hole transporting material is SMe-Ac-2;

[0067] The reaction formula of the third reaction is as follows:

[0068]

[0069] The structural formula of the pinacol borate of R is:

[0070] When, the prepared hole transporting material is SMe-Ac-3;

[0071] The reaction formula of the third reaction is as follows:

[0072]

[0073] In some embodiments, the steps of the third reaction include: dissolving the second intermediate product, the pinacol borate of R, tetrakis(triphenylphosphine)palladium, and potassium carbonate with a molar ratio of 1:(2-2.5):(0.04-0.06):(5-7) in toluene, ethyl acetate, and water (volume ratio 2:1:1), reacting at 85°C for 6 hours, cooling to room temperature, extracting with dichloromethane, drying with anhydrous magnesium sulfate, filtering, and distilling under reduced pressure. After purification by column chromatography, the hole transporting material is obtained.

[0074] In some embodiments, the eluent for column chromatography is petroleum ether and dichloromethane with a volume ratio of 4:1.

[0075] The preparation method of the hole transporting material provided by the embodiments of the present application is used to prepare the above hole transporting material. The raw materials in the preparation method are inexpensive, the preparation process is simple, suitable for industrial production, and has repeatability, and has good application prospects.

[0076] Figure 4 It is a schematic structural diagram of a perovskite battery provided by the embodiments of the present application.

[0077] Reference Figure 4, according to some embodiments of the present application, a third aspect of the embodiments of the present application further provides a perovskite solar cell, which is composed of a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes the hole transport material in the above embodiments, or the hole transport material prepared by using the preparation method in the above embodiments.

[0078] The material of the transparent conductive substrate includes ITO glass, which is processed by plating a layer of indium tin oxide (commonly known as ITO) film on the basis of soda-lime-based or borosilicate-based substrate glass by means of magnetron sputtering.

[0079] The material of the perovskite absorption layer can be a compound composed of A, B, and X 3 wherein A can be one or more of FA (HC(NH 2 ) 2 ), MA(CH 3 NH 3 ), Cs, Rb; B can be one or more of Pb, Sn, Sr; and X can be one or more of Br, I, Cl.

[0080] The materials of the electron transport layer include tin oxide, titanium dioxide, C60, fullerenes and their derivatives, etc.

[0081] The material of the electrode includes at least one of chromium (Cr) and gold (Au).

[0082] In the perovskite solar cell provided by the embodiments of the present application, the hole transport layer includes the hole transport material in the above embodiments, or the hole transport material prepared by using the preparation method in the above embodiments. The hole transport material is SMe-Ac-1, SMe-Ac-2 or SMe-Ac-3. Introducing a thiophene group into the acridine group, the group containing more sulfur atoms in the molecule endows the HTMs with increased intra- and / or intermolecular interactions, appropriate energy levels, and enhanced buried interface interactions with quasi-two-dimensional layered perovskite (Ruddlesden-Popper, RP perovskite), resulting in better mobility of the hole transport material, which is beneficial to the extraction and transport of holes, a HOMO energy level that matches the perovskite absorption layer and is relatively deep, and a relatively high decomposition temperature, having good thermal stability.

[0083] According to some embodiments of the present application, a fourth aspect of the embodiments of the present application further provides a preparation method of a perovskite battery, including:

[0084] S21. Cleaning step: Ultrasonically clean the transparent conductive substrate with deionized water, acetone, and ethanol in sequence for 15 - 20 minutes. After drying the transparent conductive substrate, perform oxygen plasma treatment for 10 - 15 minutes, and then transfer the transparent conductive substrate to a nitrogen glove box;

[0085] S22. Preparation of hole transport layer: Weigh 3 - 15 mg of the hole transport material as described in the above embodiments, or the hole transport material prepared by the preparation method of the above embodiments, dissolve it in 1 mL of chlorobenzene solution, take an appropriate amount of the mixed solution and drop it onto the transparent conductive substrate, spin - coat it at a speed of 4000 - 5000 rpm for 20 - 30 s, and then anneal it at 90 - 100 °C for 10 min;

[0086] S23. Preparation of perovskite absorption layer: Cool the transparent conductive substrate with the hole transport layer to room temperature, preheat it at 130 - 140 °C for 3 - 5 min, take 50 μL of perovskite solution and spread it over the surface of the hole transport layer, spin - coat it at a speed of 3000 - 5000 rpm for 20 - 30 s, and then anneal it at 90 - 100 °C for 10 min. Among them, the solute of the perovskite solution is 3 - bromo - benzylammonium iodide or 3 - chloro - benzylammonium iodide, methylammonium chloride, and lead iodide, and the solvent is N,N - dimethylformamide and dimethyl sulfoxide;

[0087] S24. Preparation of electron transport layer: Cool the transparent conductive substrate with the perovskite absorption layer to room temperature, take 40 μL of (6,6) - phenyl - C61 - butyric acid methyl ester solution with a concentration of 15 mg / mL, spread the (6,6) - phenyl - C61 - butyric acid methyl ester solution over the perovskite absorption layer, spin - coat it at a speed of 1000 - 2000 rpm for 30 - 50 s, and then anneal it at 70 - 80 °C for 10 min;

[0088] S25. Preparation of electrode: Place the transparent conductive substrate with the electron transport layer in a vacuum evaporation chamber, and evaporate at least one of metal chromium or gold onto the electron transport layer.

[0089] The preparation method of the perovskite battery provided by the embodiment of the present application uses the hole transport material in the above embodiments or the hole transport material prepared by the preparation method provided in the above embodiments as the hole transport layer. The hole transport materials SMe - Ac - 1, SMe - Ac - 2, and SMe - Ac - 3 have good solubility in chlorobenzene solvent, good film - forming property, good wettability with the perovskite precursor solvent, and are helpful for the crystallization and film - forming of perovskite.

[0090] The following are specific embodiments of the present application:

[0091] Example 1

[0092] Preparation of the first intermediate product: 1.36 g of 9,9-dimethyl-9,10-dihydroacridine, 4-bromothioanisole, sodium tert-butoxide, tri-tert-butylphosphine and bis(diylenebenzylacetone)palladium were added to a 100 mL round-bottom double-necked flask and dissolved in toluene. The molar ratio of 9,9-dimethyl-9,10-dihydroacridine, 4-bromothioanisole, sodium tert-butoxide, bis(diylenebenzylacetone)palladium and tri-tert-butylphosphine was 1:1.25:1:0.05:0.21, and the mixture was reacted at 100°C for 12 hours. The organic phase was extracted with a saturated sodium chloride solution and dichloromethane, dried with anhydrous magnesium sulfate, filtered, and distilled under reduced pressure. The eluent was a 6:1 volume ratio of petroleum ether and dichloromethane for column chromatography purification, and the yield was about 75%.

[0093] Preparation of the second intermediate product: Add 0.81 g of the above-mentioned first intermediate product and 50 mL of tetrahydrofuran into a 100 mL round-bottom double-necked flask, and then add N-bromosuccinimide, the molar ratio of the first intermediate product to N-bromosuccinimide is 1:2.12. After reacting at 0°C for 12 hours, the reaction is quenched with water, and the organic phase is extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, and distilled under reduced pressure. Purification is performed by column chromatography using an eluent of petroleum ether and dichloromethane in a volume ratio of 10:1, and the yield is about 95%.

[0094] Preparation of hole transport material SMe-Ac-1: In a 100 mL round-bottom double-necked flask, 0.49 g of the second intermediate product, the compound of formula VII, tetrakis(triphenylphosphine)palladium and potassium carbonate were added and dissolved in toluene, ethyl acetate and water (volume ratio 2:1:1), the molar ratio of the second intermediate product, the compound of formula VII, tetrakis(triphenylphosphine)palladium and potassium carbonate was 1:2.2:0.05:6, reacted at 85°C for 6 hours, cooled to room temperature, extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, and distilled under reduced pressure, and purified by column chromatography using an eluent of petroleum ether and dichloromethane in a volume ratio of 4:1, with a yield of about 71%.

[0095] Fabrication of perovskite solar cells: The transparent conductive substrate was ultrasonically cleaned with deionized water, acetone, and ethanol successively for 20 minutes. After drying the transparent conductive substrate, it was subjected to oxygen plasma treatment for 15 minutes, and then transferred to a nitrogen glove box. Weighed 15 mg of the hole transporting material SMe-Ac-1 as described in the above example, dissolved it in 1 mL of chlorobenzene solution. An appropriate amount of the mixed solution was dropped onto the transparent conductive substrate, spin-coated at a speed of 4500 rpm for 30 s, and then annealed at 100 °C for 10 min. The transparent conductive substrate with the hole transporting layer was cooled to room temperature, preheated at 140 °C for 5 min, and 50 μL of perovskite solution was spread over the surface of the hole transporting layer, spin-coated at a speed of 5000 rpm for 20 - 30 s, and then annealed at 100 °C for 10 min. Among them, the solute of the perovskite solution was 3-chloro-benzylammonium iodide, methylammonium chloride, and lead iodide with a molar ratio of 2.2:3.5:4, and the solvent was N,N-dimethylformamide and dimethyl sulfoxide with a volume ratio of 4:1. The transparent conductive substrate with the perovskite absorption layer was cooled to room temperature, and 40 μL of (6,6)-phenyl-C61-butyric acid methyl ester solution with a concentration of 15 mg / mL was taken, and the (6,6)-phenyl-C61-butyric acid methyl ester solution was spread over the perovskite absorption layer, spin-coated at a speed of 2000 rpm for 50 s, and then annealed at 80 °C for 10 min. The transparent conductive substrate with the electron transporting layer was placed in a vacuum evaporation chamber, and metal chromium was evaporated onto the electron transporting layer.

[0096] The preparation method of Example 2 was basically the same as that of Example 1, except that the compound of Formula VII was replaced with the compound of Formula VIII in the step of preparing the hole transporting material to prepare the hole transporting material SMe-Ac-2.

[0097] The preparation method of Example 3 was basically the same as that of Example 1, except that the compound of Formula VII was replaced with the compound of Formula IX in the step of preparing the hole transporting material to prepare the hole transporting material SMe-Ac-3.

[0098] The decomposition temperature and HOMO energy level of the hole transporting materials in Examples 1 to 3 were tested, and the test results are shown in Table 1:

[0099] Table 1 Test results of decomposition temperature and HOMO energy level of Examples 1 to 3

[0100]

[0101] According to the test results in Table 1, it was found that the hole transporting materials provided in the examples of the present application have a relatively deep HOMO energy level and a relatively high decomposition temperature, and have good thermal stability.

[0102] The photoelectric conversion efficiency, open-circuit voltage, short-circuit current, and fill factor of Examples 1 to 3 were tested, and the test results are shown in Table 2 as follows:

[0103] Table 2 Test Results of Photoelectric Conversion Efficiency, Open-Circuit Voltage, Short-Circuit Current, and Fill Factor of Examples 1 to 3

[0104]

[0105] According to the test results in Table 2, it is found that the perovskite solar cell provided by the embodiments of the present application can maintain a high short-circuit current, open-circuit voltage, and fill factor of the perovskite solar cell without using additives such as dopants or interfacial modifiers, and obtain a high photoelectric conversion efficiency.

[0106] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present application. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A hole transport material, characterized in that: The structure is as shown in Formula I: Wherein, R is selected from one of the following structural formulas II to IV:

2. A method for preparing the hole transport material according to claim 1, characterized in that: The following steps are involved: Conducting a first reaction between 9,9-dimethyl-9,10-dihydroacridine and 4-bromothioanisole to prepare a first intermediate product; Conducting a second reaction of the first intermediate product with N-bromosuccinimide to prepare a second intermediate product; Performing a third reaction between the second intermediate product and the boric acid pinacol ester of R to prepare the hole transport material; The structure of the first intermediate product is as shown in Formula V: The structure of the second intermediate product is as shown in Formula VI: The structure of the boric acid pinacol ester of R is selected from one of the following formulas VII to IX:

3. The method of hole transport material according to claim 2, characterized in that The first reaction step comprises: dissolving 9,9-dimethyl-9,10-dihydroacridine, 4-bromothioanisole, sodium tert-butoxide, bis(dibenzylideneacetone)palladium and tri-tert-butylphosphine in a molar ratio of 1:(1.1-1.3):(0.9-1.1):(0.04-0.06):(0.2-0.22) in toluene, reacting at 120° C. for 12 hours and then cooling to room temperature, extracting the organic phase with saturated sodium chloride solution and dichloromethane, drying with anhydrous magnesium sulfate, filtering, distilling under reduced pressure, and purifying by column chromatography to obtain the first intermediate product.

4. The method for preparing a hole transport material according to claim 3, characterized in that: The eluent of the column chromatography is petroleum ether and dichloromethane in a volume ratio of 6:

1.

5. The method for preparing a hole transport material according to claim 2, characterized in that: The second reaction step comprises: The first intermediate product and N-bromosuccinimide in a molar ratio of 1:(2-2.3) are dissolved in tetrahydrofuran, reacted at 0°C for 12 hours, and then the reaction is quenched with water. The organic phase is extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, and distilled under reduced pressure. The second intermediate product is purified by column chromatography.

6. The method for preparing a hole transport material according to claim 5, characterized in that: The eluent of the column chromatography is petroleum ether and dichloromethane in a volume ratio of 10:

1.

7. The method for preparing a hole transport material according to claim 2, characterized in that: The steps of the third reaction include: The second intermediate product in a molar ratio of 1: (2-2.5): (0.04-0.06): (5-7), the boric acid pinacol ester of R, tetrakis(triphenylphosphine)palladium and potassium carbonate are dissolved in toluene, ethyl acetate and water (volume ratio 2: 1: 1), reacted at 85°C for 6 hours, cooled to room temperature, extracted with dichloromethane, dried with anhydrous magnesium sulfate, filtered, distilled under reduced pressure, and purified by column chromatography to obtain the hole transport material.

8. The method for preparing a hole transport material according to claim 7, characterized in that: The eluent of the column chromatography is petroleum ether and dichloromethane in a volume ratio of 4:

1.

9. A perovskite solar cell, characterized in that: The perovskite solar cell is composed of a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer and an electrode. The hole transport layer includes the hole transport material according to claim 1, or a hole transport material prepared by the preparation method according to any one of claims 2 to 8.

10. A method for preparing a perovskite battery, characterized in that: include: Cleaning step: ultrasonically cleaning the transparent conductive substrate with deionized water, acetone and ethanol for 15 to 20 minutes in sequence, drying the transparent conductive substrate and then subjecting it to oxygen plasma treatment for 10 to 15 minutes, and then transferring the transparent conductive substrate to a nitrogen glove box; Preparation of hole transport layer: weigh 3-15 mg of the hole transport material as claimed in claim 1, or the hole transport material as claimed in claims 2-8 The hole transport material prepared by any one of the preparation methods described above is dissolved in 1 mL of chlorobenzene solution, and an appropriate amount of the mixed solution is dropped onto the transparent conductive substrate, and after spin coating at a speed of 4000-5000 rpm for 20-30 seconds, annealing at 90-100° C. for 10 minutes; Preparation of the perovskite absorption layer: cooling the transparent conductive substrate with the hole transport layer to room temperature, preheating at 130-140°C for 3-5 minutes, taking 50 μL of the perovskite solution to cover the surface of the hole transport layer, spin coating at a speed of 3000-5000 rpm for 20-30 seconds, and annealing at 90-100°C for 10 minutes, wherein the solute of the perovskite solution is 3-bromo-benzylammonium iodide or 3-chloro-benzylammonium iodide, methylammonium chloride and lead iodide, and the solvent is N,N-dimethylformamide and dimethyl sulfoxide; preparing an electron transport layer: cooling the transparent conductive substrate having the perovskite absorption layer to room temperature, taking 40 μL of a 15 mg / mL (6,6)-phenyl-C61-butyric acid methyl ester solution, spreading the (6,6)-phenyl-C61-butyric acid methyl ester solution over the perovskite absorption layer, spin coating at a speed of 1000 to 2000 rpm for 30 to 50 seconds, and annealing at 70 to 80° C. for 10 minutes; Prepare the electrode: place the transparent conductive substrate with the electron transport layer in a vacuum deposition box, and deposit at least one of metal chromium or gold on the electron transport layer.

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