Hole transport material containing benzene ring and heterocyclic structure, and use thereof

Abstract

Provided are a hole transport material and a use thereof. The hole transport material is used in the preparation of a perovskite solar battery, and can improve the efficiency and stability of the battery.

Description

Hole transport materials containing benzene ring and heterocyclic ring structures and their applications Technical Field

[0001] The present application belongs to the field of solar energy technology, and specifically relates to a hole transport material containing a benzene ring and a heterocyclic ring structure and its application. Background Art

[0002] Energy is the fundamental driving force behind global technological and economic development, and it forms the foundation of human survival and development. Since the beginning of the 21st century, energy challenges have intensified. Fossil fuels are currently the primary energy source consumed globally, but with continued exploitation, their depletion is inevitable, and most fossil fuels will be depleted within this century. Solar energy is a renewable energy source with promising applications. Solar cells, which directly convert solar radiation into electricity without polluting the environment, are an ideal way to harvest solar energy. Perovskite solar cells are garnering increasing research and attention.

[0003] Among them, organic-inorganic hybrid perovskite solar cells have the advantages of low cost, simple preparation process, and suitability for large-scale production. In just a few years, their certified efficiency has increased from 3.8% to 26.1%. The efficiency of perovskite and crystalline silicon stacked cells has reached more than 33%, making them solar cells with great commercial application value in the future.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a hole transport material and its application in solar cells.

[0006] Specifically, this application involves the following aspects:

[0007] 1. A hole transport material, which is a compound represented by formula (I):

[0008] wherein Ring A and Ring B are independently selected from aromatic rings, condensed aromatic hydrocarbons, benzoheterocyclic rings, heteroaromatic rings, substituted aromatic rings, substituted condensed aromatic hydrocarbons, substituted benzoheterocyclic rings, and substituted heteroaromatic rings;

[0009] The C ring is selected from a five- to eight-membered ring containing a heteroatom X, wherein the heteroatom X is selected from oxygen, sulfur or nitrogen. When the heteroatom X is nitrogen, R3 is attached thereto, wherein R3 is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl having 1-40 carbon atoms, heteroalkyl having 1-40 carbon atoms, cycloalkyl having 3-40 carbon atoms, heterocycloalkyl having 2-40 carbon atoms, aralkyl having 7-40 carbon atoms, heteroaralkyl having 2-40 carbon atoms, aryl having 6-40 carbon atoms, heteroaryl having 1-40 carbon atoms, alkoxy having 1-40 carbon atoms, alkylthio having 1-40 carbon atoms, aryloxy having 6-30 carbon atoms, arylthio having 6-30 carbon atoms, phosphate group, sulfonic acid group, and carboxylic acid group;

[0010] One or both of R1 and R2 are selected from the following substituents:

[0011] When one of R1 or R2 is not a substituent represented by formula (a), (b), (c), (d), (e), (f), (g), (h), or (i), it is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl having 1-40 carbon atoms, heteroalkyl having 1-40 carbon atoms, cycloalkyl having 3-40 carbon atoms, heterocycloalkyl having 2-40 carbon atoms, aralkyl having 7-40 carbon atoms, heteroaralkyl having 2-40 carbon atoms, aryl having 6-40 carbon atoms, heteroaryl having 1-40 carbon atoms, alkoxy having 1-40 carbon atoms, alkylthio having 1-40 carbon atoms, aryloxy having 6-30 carbon atoms, arylthio having 6-30 carbon atoms, phosphoric acid group, sulfonic acid group, and carboxylic acid group;

[0012] Y and Z are independently selected from oxygen, sulfur, NH or CH2, wherein Y is preferably CH2 and Z is preferably oxygen;

[0013] n is an integer of 0-20, preferably an integer of 1-10.

[0014] 2. The hole transport material according to item 1, wherein the A ring and the B ring are independently selected from:

[0015] 3. The hole transport material according to item 1 or 2, wherein the C ring is selected from:

[0016] 4. The hole transport material according to any one of items 1 to 3, wherein one of R1 or R2 is a substituent represented by formula (a).

[0017] 5. The hole transport material according to any one of items 1 to 4, wherein the heteroatom X in the C ring is nitrogen, and R3 is selected from a methyl group, an ethyl group, or a phenyl group.

[0018] 6. A hole transport material according to any one of items 1 to 5, wherein when one of R1 or R2 is not a substituent represented by formula (a), formula (b), formula (c), formula (d), formula (e), (f), formula (g), formula (h), or formula (i), it is selected from hydrogen, methylthio or methoxy.

[0019] 7. The hole transport material according to any one of items 1 to 6, wherein ring A is a benzene ring, ring B is a benzene ring, and ring C is One of R1 and R2 is Z is oxygen, Y is CH2, n is an integer of 1-10 (eg, 2, 3, 4), and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

[0020] 8. The hole transport material according to any one of items 1 to 7, wherein ring A is a benzene ring, ring B is a benzene ring, and ring C is One of R1 and R2 is Z and Y are both CH2, n is an integer of 1-10 (eg, 1, 2, 3), and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

[0021] 9. The hole transport material according to any one of items 1 to 8, wherein the hole transport material is selected from:

[0022] 10. Use of the hole transport material according to any one of items 1 to 9 in a solar cell.

[0023] 11. The use according to item 10, wherein the solar cell is a perovskite solar cell.

[0024] 12. A solar cell comprising a hole transport layer formed of the hole transport material according to any one of items 1 to 9.

[0025] 13. The solar cell according to item 12, wherein the solar cell is a perovskite solar cell.

[0026] 14. The solar cell according to item 13, wherein the perovskite solar cell comprises a substrate, a transparent conductive layer, the hole transport layer, a perovskite absorption layer, an electron transport layer and an electrode stacked in sequence.

[0027] 15. The solar cell according to any one of items 12 to 14, wherein the hole transport layer has a thickness of 20 to 200 nm.

[0028] The hole transport material of the present application connects the anchoring group to the aromatic ring through an alkyl chain or a heteroalkyl chain, changing the overall molecular structure from a hole with large steric hindrance like a "T" to a material with small steric hindrance like a "7" or a "1", thereby increasing the number of anchored holes per unit area and improving the efficiency of the device; according to the bond energy data, the anchoring group connected to the aromatic ring also increases the stability of the material, thereby enhancing the stability of the device; multiple substitution sites on the aromatic ring and the substitution sites of heteroatoms on the heterocycle increase the range of controllable energy levels of the device. The hole transport material of the present application is applied to the preparation of perovskite solar cells to improve the efficiency and stability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of the perovskite solar cell of the present application.

[0030] Reference numerals: 1 substrate, 2 transparent conductive layer, 3 hole transport layer, 4 perovskite absorption layer, 5 electron transport layer, 6 electrode. DETAILED DESCRIPTION

[0031] The present application is further described below with reference to examples. It should be understood that the examples are only used to further illustrate and explain the present application and are not intended to limit the present application.

[0032] Unless otherwise defined, technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art. Although methods and materials similar or identical to those described herein may be used in experiments or practical applications, the materials and methods are described herein below. In the event of a conflict, the present specification, including definitions, will prevail. In addition, the materials, methods, and examples are provided for illustrative purposes only and are not intended to be limiting. The present application is further described below with reference to specific examples, which are not intended to limit the scope of this application.

[0033] definition

[0034] The term "substituted" as used herein refers to that one or more hydrogen atoms of a designated moiety are replaced by a suitable substituent. When the term "substituted" is modified by the term "optionally", it means that one or more hydrogen atoms of a designated moiety may be replaced by a suitable substituent or may not be replaced by any substituent.

[0035] As used herein, the term "alkyl", whether used as part of another term or used independently, refers to a saturated straight or branched chain hydrocarbon group. Examples of alkyl groups include, but are not limited to, methyl, ethyl, 1-propyl (n-propyl), 2-propyl (isopropyl), 1-butyl (n-butyl), 2-methyl-1-propyl (isobutyl), 2-butyl (neobutyl), 2-methyl-2-propyl (tert-butyl), and the like.

[0036] The term "heteroalkyl" as used herein refers to an alkyl group in which one or more carbon atoms are independently substituted with one or more heteroatoms selected from N, O and S, such as, but not limited to, alkoxy, alkylthio, and the like.

[0037] The term "halogen" as used herein refers to F, Cl, Br or I.

[0038] As used herein, the term "cyano" refers to -CN.

[0039] As used herein, the terms "aryl," "aromatic ring," or "aromatic ring," whether used as part of another term or independently, refer to a monocyclic or polycyclic ring system having a total of 6 to 15 ring members, wherein at least one ring in the ring system is aromatic, and each ring in the ring system contains 3 to 12 ring members. Examples of "aryl," "aromatic ring," or "aromatic ring" include, but are not limited to, phenyl, biphenyl, naphthyl, anthracenyl, and the like, each of which may have one or more substituents.

[0040] The term "fused ring aryl" or "fused ring arene" as used herein refers to a group in which an aromatic ring is fused to one or more additional rings, which may also be considered to be included within the scope of the terms "aryl", "aromatic ring" or "aromatic ring" as used herein.

[0041] As used herein, the terms "cycloalkyl," "carbocyclyl," and "carbocycle," used interchangeably, whether used as part of another term or used independently, refer to saturated, partially unsaturated, or fully unsaturated (i.e., aromatic) monocyclic and polycyclic ring systems in which all ring atoms are carbon, including at least 3 ring-forming carbon atoms.

[0042] As used herein, the term "heteroaryl" or "heteroaryl ring", whether used as part of another term or used independently, refers to an aryl group having, in addition to carbon atoms, one or more heteroatoms selected from N, O, and S, which may be optionally substituted independently with one or more substituents as described herein. Heteroaryl groups can be monocyclic or polycyclic, and examples include, but are not limited to, thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, benzofuranyl, pteridinyl, and the like.

[0043] The term "alkoxy" as used herein, whether used as part of another term or used independently, refers to an alkyl group as defined above that is attached to the parent molecule through an oxygen atom. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy (e.g., n-propoxy and isopropoxy), tert-butoxy, neopentyloxy, n-hexyloxy, and the like.

[0044] As used herein, the term "heteroaralkyl" refers to an alkyl group as defined above substituted with a heteroaryl group as defined above.

[0045] As used herein, the term "benzoheterocyclyl" refers to a group in which a benzene ring is fused to a heterocyclyl group (ie, the benzene ring and the heterocyclyl group share two adjacent carbon atoms).

[0046] Currently, common perovskite solar cells consist of a conductive glass substrate (ITO), a hole transport layer (HTL), a perovskite layer, an electron transport layer, and metal electrodes. The HTL is responsible for extracting and transporting photogenerated holes, significantly impacting device efficiency and stability. (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz) is a commonly used hole transport material. Because the phosphate anchoring group in the MeO-2PACz molecule is linked to the nitrogen atom of the carbazole via an alkyl group, the entire molecule resembles a large "T" shape, with the anchoring group at the bottom and the two aromatic rings of the carbazole at either end of the anchoring chain. Due to steric hindrance, the molecular packing per unit area is relatively small, resulting in weak hole extraction and low device efficiency.

[0047] According to bond energy data, the bond energy of a carbon-carbon single bond is 332 kJ / mol, the bond energy of a carbon-oxygen single bond is 326 kJ / mol, and the bond energy of a carbon-nitrogen bond is 305 kJ / mol. The greater the bond energy, the higher the stability. Therefore, it is not difficult to see that the anchor group attached to the nitrogen atom via the alkyl chain has poor stability. Furthermore, the proximity of the anchor group, phosphoric acid (or other acid), to the nitrogen atom can easily cause the nitrogen atom to become an ammonium salt. Ammonium salts have poor thermal stability and are easily decomposed by heat. Most perovskite thin films undergo annealing, resulting in poor thermal stability.

[0048] Hole materials like MeO-2PACz mostly only modify the anchoring group and the length of the alkyl chain connecting the carbazole core to the anchoring group, while modifications to the aromatic ring are rare. When modifications are made, they are only to introduce simple small molecules such as methyl, methoxy, and halogen. These modifications cannot significantly change the overall structure of the molecule, and therefore the energy level of the molecule will not change much, making it difficult to find hole materials that are suitable for device energy levels. Introducing large molecular modifications to the aromatic ring, such as phenyl molecules, may match the energy level of the device and improve the device's switching voltage, but most of them have very poor solubility due to the excessive conjugation structure, which is not conducive to practical application in devices. In addition, the use of such holes will lead to a significant decrease in the device's fill factor and overall efficiency.

[0049] In order to solve these problems existing in the prior art, the present application provides a hole transport material, which is a compound represented by formula (I):

[0050] wherein Ring A and Ring B are independently selected from aromatic rings, condensed aromatic hydrocarbons, benzoheterocyclic rings, heteroaromatic rings, substituted aromatic rings, substituted condensed aromatic hydrocarbons, substituted benzoheterocyclic rings, and substituted heteroaromatic rings;

[0051] The C ring is selected from a five- to eight-membered ring containing a heteroatom X, wherein the heteroatom is selected from oxygen, sulfur or nitrogen. When the heteroatom X is nitrogen, R3 is attached thereto, wherein R3 is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl having 1-40 carbon atoms, heteroalkyl having 1-40 carbon atoms, cycloalkyl having 3-40 carbon atoms, heterocycloalkyl having 2-40 carbon atoms, aralkyl having 7-40 carbon atoms, heteroaralkyl having 2-40 carbon atoms, aryl having 6-40 carbon atoms, heteroaryl having 1-40 carbon atoms, alkoxy having 1-40 carbon atoms, alkylthio having 1-40 carbon atoms, aryloxy having 6-30 carbon atoms, arylthio having 6-30 carbon atoms, phosphate group, sulfonic acid group, and carboxylic acid group;

[0052] One or both of R1 and R2 are selected from the following substituents:

[0053] When one of R1 or R2 is not a substituent represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i), it is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl having 1-40 carbon atoms, heteroalkyl having 1-40 carbon atoms, cycloalkyl having 3-40 carbon atoms, heterocycloalkyl having 2-40 carbon atoms, aralkyl having 7-40 carbon atoms, heteroaralkyl having 2-40 carbon atoms, aryl having 6-40 carbon atoms, heteroaryl having 1-40 carbon atoms, alkoxy having 1-40 carbon atoms, alkylthio having 1-40 carbon atoms, aryloxy having 6-30 carbon atoms, arylthio having 6-30 carbon atoms, phosphoric acid group, sulfonic acid group, and carboxylic acid group.

[0054] In one embodiment, Ring A and Ring B are independently selected from:

[0055] In one embodiment, ring A is a benzene ring, and ring B is a benzene ring.

[0056] In one embodiment, the C ring is selected from:

[0057] In one embodiment, the C ring is

[0058] In one embodiment, the C ring is R3 is selected from methyl, ethyl, or phenyl.

[0059] In one embodiment, Y and Z are independently selected from oxygen, sulfur, NH or CH2.

[0060] In one embodiment, Y is CH2.

[0061] In one embodiment, Z is oxygen.

[0062] In one embodiment, n is an integer from 0 to 20, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0063] In one embodiment, n is an integer from 1 to 10.

[0064] In one embodiment, when one of R1 or R2 is not a substituent represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i), it is selected from hydrogen, methylthio or methoxy.

[0065] In one embodiment, ring A is a benzene ring, ring B is a benzene ring, and ring C is One or both of R1 and R2 are Z is oxygen, Y is CH2, and n is an integer of 1-10.

[0066] In one embodiment, ring A is a benzene ring, ring B is a benzene ring, and ring C is One of R1 and R2 is Z is oxygen, Y is CH2, n is an integer from 1 to 10, and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

[0067] In one embodiment, ring A is a benzene ring, ring B is a benzene ring, and ring C is One of R1 and R2 is Z and Y are both CH2, n is an integer of 1-10 (eg, 1, 2, 3), and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

[0068] In one embodiment, the hole transport material is selected from:

[0069] The hole transport material of the present application connects the anchoring group to the aromatic ring through an alkyl chain or a heteroalkyl chain, changing the overall molecular structure from a hole with large steric hindrance like a "T" to a material with small steric hindrance like a "7" or a "1", thereby increasing the number of anchored holes per unit area and improving the efficiency of the device; according to the bond energy data, the anchoring group connected to the aromatic ring also increases the stability of the material, thereby enhancing the stability of the device; multiple substitution sites on the aromatic ring and the substitution sites of heteroatoms on the heterocycle increase the range of controllable energy levels of the device. The hole transport material of the present application is applied to the preparation of perovskite solar cells to improve the efficiency and stability of the battery.

[0070] The present application also provides use of any of the above-mentioned hole transport materials in solar cells.

[0071] Those skilled in the art will appreciate that the type of solar cell may include any solar cell that can use the hole transport material of the present application.

[0072] In a specific embodiment, the solar cell is a perovskite solar cell. The perovskite solar cell may include a single perovskite solar cell and a perovskite tandem solar cell including a perovskite absorber layer.

[0073] The present application also provides a solar cell comprising any one of the above hole transport materials. The solar cell differs from existing perovskite solar cells at least in that a layer formed by any one of the above hole transport materials is used as a hole transport layer.

[0074] The hole transport layer can be prepared by methods known in the art, for example, by evaporation, solution spin coating, slit coating, or printing.

[0075] In a specific embodiment, the hole transport layer is obtained by solution spin coating, specifically, the hole transport layer can be obtained by spin coating a solution containing 10-50 mg / mL of hole transport material.

[0076] Those skilled in the art will appreciate that the thickness of the hole transport layer can be adjusted according to actual needs.

[0077] In a specific embodiment, the thickness of the hole transport layer is 20-200 nm, for example, it can be 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, and any ranges therebetween.

[0078] In a specific embodiment, the solar cell is a perovskite solar cell.

[0079] Figure 1 shows a typical structural schematic diagram of a perovskite solar cell, which includes a substrate 1, a transparent conductive layer 2, a hole transport layer 3, a perovskite absorption layer 4, an electron transport layer 5 and an electrode 6 stacked in sequence, wherein the hole transport layer 3 is formed by any one of the above-mentioned hole transport materials, for example, by a compound represented by formula (I).

[0080] For the specific material selection or thickness of each layer of the substrate 1 , transparent conductive layer 2 , perovskite absorption layer 4 , electron transport layer 5 and electrode 6 , corresponding materials and thicknesses known in the art can be used.

[0081] For example, the substrate 1 may be a transparent substrate made of glass or an organic polymer such as PET.

[0082] The transparent conductive layer 2 may be made of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), etc. The thickness of the transparent conductive layer 2 may be 50-500 nm.

[0083] The perovskite absorption layer 4 absorbs incident photons and generates photogenerated carriers (holes and electrons). The general chemical formula of the perovskite absorption layer 4 is ABX m Y 3-m , wherein A is a monovalent cation such as CH3NH3, C4H9NH3, NH2=CHNH2, or Cs; B is a divalent metal such as Pb or Sn; X is Cl, Br, or I; Y is Cl, Br, or I, and X and Y are not the same element; m = 1, 2, or 3. The thickness of the perovskite absorber layer 4 can be 200-1000 nm.

[0084] The electron transport layer 5 realizes the longitudinal transport of carriers and can be made of tin oxide (SnO2), PC61BM, PC71BM, etc. The thickness of the electron transport layer 5 can be 10-100 nm.

[0085] The electrode 6 may be made of Au, Ag, C or Cu, and may have a thickness of 50-500 nm.

[0086] Example

[0087] Synthesis of hole transport materials

[0088] (1) The synthesis process of compound 1 is as follows:

[0089] The synthesis steps of compound 1 are as follows:

[0090] Step 1: Place 2 g of 3-bromo-9-ethylcarbazole, 0.15 g of copper acetylacetonate, 0.25 g of N1,N2-bis(4-hydroxy-2,6-dimethylphenyl)oxalamide, and 1.0 g of lithium hydroxide monohydrate into a Shrek tube. The gas was replaced three times, followed by nitrogen. 6.4 g of DMSO and 1.6 g of water were added, the lid was tightened, and the mixture was heated to 100°C with stirring for 12 hours. Thin-layer chromatography confirmed the complete reaction of the starting material 3-bromo-9-ethylcarbazole. The mixture was cooled to room temperature and extracted with ethyl acetate (200 mL) and water (100 mL). After standing, the organic phase was separated and dried over 10 g of anhydrous magnesium sulfate for 15 minutes. The filtrate was filtered and the solvent removed by rotary evaporation. The resulting liquid was purified by column chromatography using a 1:9 mixture of ethyl acetate and petroleum ether to obtain compound 1a (1.6 g).

[0091] Step 2: 1.6 g of compound 1a, 1,3-dibromopropane, potassium carbonate, and acetonitrile were added to a 250 mL three-necked flask in sequence, and the air in the system was replaced three times by vacuum-nitrogen filling. A nitrogen balloon was connected to provide an inert gas protective atmosphere. The reaction was stirred and heated for 24 hours. The reaction of the raw material compound 1a was confirmed to be complete by thin layer chromatography. The temperature was naturally cooled to room temperature, and extracted with ethyl acetate (200 mL) and water (100 mL). After standing, the organic phase was separated and dried with 10 g of anhydrous magnesium sulfate for 15 minutes. The filtrate was filtered and the solvent was removed by rotary evaporator. The resulting liquid was purified by column chromatography with a mixed solvent of ethyl acetate: petroleum ether = 1:9 to obtain compound 1b (1.2 g).

[0092] Step 3: 1.2 g of compound 1b and triethyl phosphite were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuuming and filling with nitrogen. A nitrogen balloon was connected to provide an inert gas protective atmosphere. The mixture was heated to reflux and stirred for 24 hours. The mixture was cooled to room temperature naturally. The solvent was removed by rotary evaporation. The resulting liquid was purified by column chromatography using a mixed solvent of ethyl acetate and petroleum ether in a ratio of 1:1 to obtain compound 1c (0.6 g).

[0093] Step 4: 0.6 g of compound 1c and 10 mL of 1,4-dioxane were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuuming and filling with nitrogen. A nitrogen balloon was connected to provide an inert gas protective atmosphere. 6 mL of trimethylsilyl bromide was added dropwise to the three-necked flask and stirred for 24 hours. The reaction of the raw material compound 1c was confirmed to be complete by thin layer chromatography. 50 mL of water was added to the reaction solution and stirred for 12 hours. A large amount of solid precipitated in the reaction flask. The solid was filtered and washed with water. The resulting solid was recrystallized from a mixed solvent of tetrahydrofuran: dichloromethane = 1:3 to obtain compound 1 (0.4 g).

[0094] (2) Preparation of Compounds 2-5

[0095] The preparation method of compound 2 is the same as that of compound 1, except that 1,2-dibromoethane is used instead of 1,3-dibromopropane in step 2.

[0096] The preparation method of compound 3 is the same as that of compound 1, except that 1,4-dibromobutane is used instead of 1,3-dibromopropane in step 2.

[0097] The preparation method of compound 4 is the same as that of compound 1, except that step 1 is omitted, 9-methyl-9H-carbazole-1-ol is used to replace compound 1a, and 1,2-dibromoethane is used to replace 1,3-dibromopropane in step 2.

[0098] The preparation method of compound 5 is the same as that of compound 1, except that step 1 is omitted, 9-methyl-9H-carbazole-2-ol is used to replace compound 1a, and 1,2-dibromoethane is used to replace 1,3-dibromopropane in step 2.

[0099] (3) The synthesis process of compound 6 is as follows:

[0100] Step 1: 2g 2-bromo-7-methoxycarbazole, 80ml acetonitrile, 0.3g tetrabutylammonium bromide, 5g potassium hydroxide aqueous solution (50%) were added to a flask in sequence, heated to 50 degrees, stirred for 1h, 1.5g iodine ethane was added, and stirred at 50 degrees overnight. The reaction of the raw material 2-bromo-7-methoxycarbazole was confirmed to be complete by thin layer chromatography, and the temperature was naturally cooled to room temperature. It was extracted with ethyl acetate (200mL) and water (100mL), and the organic phase was separated after standing. It was dried with 10g anhydrous magnesium sulfate for 15min, filtered, and the filtrate was freed from the solvent by a rotary evaporator. The resulting liquid was purified by column chromatography with a mixed solvent of ethyl acetate: petroleum ether = 1:9 to obtain 2g of compound 6a.

[0101] Step 2: 2g of compound 6a, 0.15g of copper acetylacetonate, 0.25g of N1,N2-bis(4-hydroxy-2,6-dimethylphenyl)oxalamide, and 1.0g of lithium hydroxide monohydrate were placed in a Shrek tube. The gas was replaced three times, nitrogen was introduced, 6.4g of DMSO and 1.6g of water were added, the lid was tightened, and the mixture was heated to 100°C with stirring for 12 hours. The reaction of raw material 6a was confirmed to be complete by thin layer chromatography. The mixture was cooled to room temperature and extracted with ethyl acetate (200mL) and water (100mL). After standing, the organic phase was separated and dried over 10g of anhydrous magnesium sulfate for 15 minutes. The filtrate was filtered and the solvent was removed by rotary evaporation. The resulting liquid was purified by column chromatography using a mixed solvent of ethyl acetate: petroleum ether = 1:9 to obtain compound 6b (1.7g).

[0102] Step 3: 1.7 g of compound 6b, 1,3-dibromopropane, potassium carbonate, and acetonitrile were added to a 250 mL three-necked flask in sequence, and the air in the system was replaced three times by vacuum-nitrogen filling. A nitrogen balloon was connected to provide an inert gas protective atmosphere. The reaction was stirred and heated for 24 hours. The reaction of the raw material compound 6b was confirmed to be complete by thin layer chromatography. The temperature was naturally cooled to room temperature, and extracted with ethyl acetate (200 mL) and water (100 mL). After standing, the organic phase was separated and dried with 10 g of anhydrous magnesium sulfate for 15 minutes. The filtrate was filtered and the solvent was removed by rotary evaporator. The resulting liquid was purified by column chromatography with a mixed solvent of ethyl acetate: petroleum ether = 1:9 to obtain compound 6c (1.6 g).

[0103] Step 4: 1.6 g of compound 6c and triethyl phosphite were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuum-filling with nitrogen. A nitrogen balloon was connected to provide an inert gas protective atmosphere. The mixture was heated to reflux and stirred for 24 hours. The mixture was cooled to room temperature naturally. The solvent was removed by rotary evaporation. The resulting liquid was purified by column chromatography using a mixed solvent of ethyl acetate: petroleum ether = 1:1 to obtain compound 6d (1.5 g).

[0104] Step 5: 1.2 g of compound 6d and 10 mL of 1,4-dioxane were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuum-nitrogen filling. A nitrogen balloon was connected to provide an inert gas protective atmosphere. 6 mL of trimethylsilyl bromide was added dropwise to the three-necked flask and stirred for 24 hours. The reaction of the raw material compound 3 was confirmed to be complete by thin layer chromatography. 50 mL of water was added to the reaction solution and stirred for 12 hours. A large amount of solid precipitated in the reaction flask. The solid was filtered and washed with water. The resulting solid was recrystallized from a mixed solvent of tetrahydrofuran: petroleum ether = 1:3 to obtain compound 6 (1.3 g).

[0105] (4) The synthesis process of compound 7 is as follows:

[0106] The synthesis steps of compound 7 are as follows:

[0107] Step 1: 2 g of 3-bromo-N-phenylcarbazole (1 equivalent), nickel chloride (0.05 equivalent), ligand (0.1 equivalent), and 50 mL of tetrahydrofuran were added sequentially to a reaction flask. The gas was replaced three times, nitrogen was introduced, and vinylmagnesium bromide (3 equivalents) was added dropwise via syringe. The mixture was heated to 60°C with stirring for 24 hours. The reaction of the starting material 3-bromo-N-phenylcarbazole was confirmed to be complete by thin-layer chromatography. The temperature was naturally cooled to room temperature and quenched by dropwise addition of saturated ammonium chloride solution. The mixture was extracted with ethyl acetate (200 mL) and water (100 mL). After standing, the organic phase was separated and dried over anhydrous magnesium sulfate for 15 minutes. The filtrate was filtered and the solvent removed by rotary evaporation. The resulting liquid was purified by column chromatography using a mixed solvent of ethyl acetate: petroleum ether = 1:19 to obtain compound 7a (1.5 g).

[0108] Step 2: 1.5 g of compound 7a (1 equivalent), 50 mL of cyclohexane, and benzoyl peroxide (0.1 equivalent) were added to the reaction flask in sequence. The air in the system was replaced three times by vacuum-nitrogen filling. A nitrogen balloon was connected to provide an inert gas protective atmosphere. Aqueous hydrogen bromide solution (5 equivalents) was added dropwise with a syringe and heated to 50 ° C. Stirring for 24 hours. The reaction of the raw material compound 7a was confirmed to be complete by thin layer chromatography. The temperature was naturally cooled to room temperature and extracted with ethyl acetate (200 mL) and water (100 mL). After standing, the organic phase was separated and dried over anhydrous magnesium sulfate for 15 min. The filtrate was filtered and the solvent was removed by rotary evaporator. The resulting liquid was purified by column chromatography with a mixed solvent of ethyl acetate: petroleum ether = 1:9 to obtain compound 7b (1.5 g).

[0109] Step 3: 1.5 g of compound 7b and triethyl phosphite were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuum-filling with nitrogen. A nitrogen balloon was connected to provide an inert gas protective atmosphere. The mixture was heated to reflux and stirred for 24 hours. The mixture was cooled to room temperature naturally. The solvent was removed by rotary evaporation. The resulting liquid was purified by column chromatography using a mixed solvent of ethyl acetate: petroleum ether = 1:1 to obtain compound 7c (1.3 g).

[0110] Step 4: 1.3 g of compound 7c and 10 mL of 1,4-dioxane were added to a 250 mL three-necked flask in sequence. The air in the system was replaced three times by vacuuming and filling with nitrogen. A nitrogen balloon was connected to provide an inert gas protective atmosphere. 6 mL of trimethylsilyl bromide was added dropwise to the three-necked flask and stirred for 24 hours. The reaction of the raw material compound 7c was confirmed to be complete by thin layer chromatography. 50 mL of water was added to the reaction solution and stirred for 12 hours. A large amount of solid precipitated in the reaction flask. The solid was filtered and washed with water. The resulting solid was recrystallized from a mixed solvent of tetrahydrofuran: petroleum ether = 1:3 to obtain compound 7 (1.0 g).

[0111] (5) Synthesis of Compounds 8-9

[0112] The preparation method of compound 8 is the same as that of compound 7, except that allylmagnesium bromide is used instead of vinylmagnesium bromide in step 1. The preparation method of compound 9 is the same as that of compound 7, except that 3-butenylmagnesium bromide is used instead of vinylmagnesium bromide in step 1.

[0113] Example 1

[0114] The hole transport material used in this example is Compound 1.

[0115] 1. A transparent conductive indium tin oxide (ITO) film with a thickness of 300 nm and a square resistance of 20 Ω / sq was deposited on a glass substrate using the APCVD (atmospheric pressure chemical vapor deposition) method. The film was cut into 2 cm × 2 cm squares and cleaned with anhydrous ethanol.

[0116] 2. Prepare a hole transport layer on the substrate. Prepare a toluene solution of Compound 1 at a concentration of 10-50 mg / mL and sonicate for 15 minutes. Spin-coat the toluene solution of Compound 1 onto the pretreated substrate at a speed of 1500-5000 rpm for 15-45 seconds.

[0117] 3. A perovskite layer was prepared by two-step spin coating on the hole transport layer substrate. A lead iodide solution (1.5 M, DMSO:DMF = 9:1) was prepared and spin-coated to form a precursor layer. The precursor layer was then heated on a hot plate at 70°C for 1 minute. After cooling, an isopropanol solution of FAI / MABr / MACl (FAI:MABr:MACl = 9:1:1, 60 mg / mL) was spin-coated. Immediately after spin coating, the layer was heated on a hot plate at 150°C for 20 minutes. The perovskite layer was approximately 500 nm thick.

[0118] 4. Spin-coat SnO2 nanoparticles onto the perovskite layer as an electron transport layer. The thickness of the electron transport layer is 10 nm.

[0119] 5. Prepare silver electrodes by evaporation with a thickness of 100 nm.

[0120] A perovskite solar cell was prepared.

[0121] Example 2

[0122] The only difference between Example 2 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 2.

[0123] Example 3

[0124] The only difference between Example 3 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 3.

[0125] Example 4

[0126] The only difference between Example 4 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 4.

[0127] Example 5

[0128] The only difference between Example 5 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 5.

[0129] Example 6

[0130] The only difference between Example 6 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 6.

[0131] Example 7

[0132] The only difference between Example 7 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 7.

[0133] Example 8

[0134] The only difference between Example 8 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 8.

[0135] Example 9

[0136] The only difference between Example 9 and Example 1 is that a different compound is used in the hole transport layer. The compound used in this example is Compound 9.

[0137] Comparative Example

[0138] The only difference between the comparative example and Example 1 is that a different compound is used in the hole transport layer. The compound used in the comparative example is (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz).

[0139] According to the IEC 60904-1-2020 standard, the performance of the perovskite solar cells prepared in the above examples and comparative examples was tested. The test results are shown in Table 1.

[0140] Table 1 Comparison of performance parameters of optimal perovskite battery devices based on different hole transport layers

[0141] By comparing the examples with the comparative examples, it can be seen that the hole transport materials of the present application have a gain effect on the device. By comparing Example 1 with Example 2 and Example 3, the effect of the length of the side chain with heteroatoms on the device is studied, and it can be seen that Example 1 has a better effect. By comparing Example 1 with Example 4 and Example 5, the effect of the hole side chain at different positions on the aromatic ring on the device is explored, and it can be seen that Example 3 has a better effect. Example 6 explores the effect of introducing a methoxy group on the device. By comparing Example 7, Example 8 and Example 9, the effect of the length of the side chain without heteroatoms on the device is explored, and it can be seen that Example 8 has a better effect.

[0142] From a comprehensive comparison, the hole transport materials of the present application have a more obvious improvement on the device's turn-on voltage.

Claims

1. A hole transport material, which is a compound represented by formula (I): in, Ring A and Ring B are independently selected from aromatic rings, condensed aromatic hydrocarbons, benzoheterocyclic rings, heteroaromatic rings, substituted aromatic rings, substituted condensed aromatic hydrocarbons, substituted benzoheterocyclic rings, and substituted heteroaromatic rings; The C ring is selected from a five- to eight-membered ring containing a heteroatom X, wherein the heteroatom X is selected from oxygen, sulfur or nitrogen. When the heteroatom X is nitrogen, R3 is connected thereto, wherein R3 is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl with 1-40 carbon atoms, heteroalkyl with 1-40 carbon atoms, cycloalkyl with 3-40 carbon atoms, heterocycloalkyl with 2-40 carbon atoms, aralkyl with 7-40 carbon atoms, heteroaralkyl with 2-40 carbon atoms, aryl with 6-40 carbon atoms, heteroaryl with 1-40 carbon atoms, alkoxy with 1-40 carbon atoms, alkylthio with 1-40 carbon atoms, aryloxy with 6-30 carbon atoms, arylthio with 6-30 carbon atoms, phosphoric acid group, sulfonic acid group, carboxylic acid group; One or both of R1 and R2 are selected from the following substituents: When one of R1 or R2 is not a substituent represented by formula (a), (b), (c), (d), (e), (f), (g), (h), or (i), it is selected from hydrogen, deuterium, tritium, cyano, halogen, alkyl having 1 to 40 carbon atoms, heteroalkyl having 1 to 40 carbon atoms, cycloalkyl having 3 to 40 carbon atoms, heterocycloalkyl having 2 to 40 carbon atoms, aralkyl having 7 to 40 carbon atoms, heteroaralkyl having 2 to 40 carbon atoms, aryl having 6 to 40 carbon atoms, heteroaryl having 1 to 40 carbon atoms, alkoxy having 1 to 40 carbon atoms, alkylthio having 1 to 40 carbon atoms, aryloxy having 6 to 30 carbon atoms, arylthio having 6 to 30 carbon atoms, phosphoric acid group, sulfonic acid group, and carboxylic acid group; Y and Z are independently selected from oxygen, sulfur, NH or CH 2, , wherein Y is preferably CH2 and Z is preferably oxygen; n is an integer of 0-20, preferably an integer of 1-10.

2. The hole transport material according to claim 1, wherein the A ring and the B ring are independently selected from:

3. The hole transport material according to claim 1 or 2, wherein the C ring is selected from: 4 . The hole transport material according to claim 1 , wherein one of R1 and R2 is a substituent represented by formula (a).

5. The hole transport material according to any one of claims 1 to 4, wherein the heteroatom X in the C ring is nitrogen, and R3 is selected from methyl, ethyl, or phenyl.

6. A hole transport material according to any one of claims 1 to 5, wherein when one of R1 or R2 is not a substituent represented by formula (a), formula (b), formula (c), formula (d), formula (e), formula (f), formula (g), formula (h), or formula (i), it is selected from hydrogen, methylthio or methoxy.

7. The hole transport material according to any one of claims 1 to 6, wherein the A ring is a benzene ring, the B ring is a benzene ring, and the C ring is One of R1 and R2 is Z is oxygen, Y is CH2, n is an integer of 1-10 (eg, 2, 3, 4), and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

8. The hole transport material according to any one of claims 1 to 7, wherein the A ring is a benzene ring, the B ring is a benzene ring, and the C ring is One of R1 and R2 is Z and Y are both CH2, n is an integer of 1-10 (eg, 1, 2, 3), and the other of R1 and R2 is selected from hydrogen, methylthio or methoxy.

9. The hole transport material according to any one of claims 1 to 8, wherein the hole transport material is selected from:

10. Use of the hole transport material according to any one of claims 1 to 9 in a solar cell.

11. The use according to claim 10, wherein the solar cell is a perovskite solar cell. 12 . A solar cell comprising a hole transport layer formed by the hole transport material according to claim 1 .

13. The solar cell according to claim 12, wherein the solar cell is a perovskite solar cell.

14. The solar cell according to claim 13, wherein the perovskite solar cell comprises a substrate, a transparent conductive layer, the hole transport layer, a perovskite absorption layer, an electron transport layer and an electrode which are stacked in sequence.

15. The solar cell according to any one of claims 12 to 14, wherein the hole transport layer has a thickness of 20 to 200 nm.

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