Self-assembled monomolecular layer hole transport material, hole transport layer and battery thereof

Abstract

The invention discloses a self-assembled monomolecular layer hole transport material, a hole transport layer and a battery thereof. According to the present invention, the compound having different anchoring groups and represented by the formula (I) can be subjected to firm self-assembly with the substrate surface through the chemical bonding manner, such that the good coverage rate is provided, the film forming quality is increased, and the transmission performance is improved; and meanwhile, the material has a rigid conjugate large-plane condensed ring core structure, so that the hole transmission performance of the material is ensured, and the photovoltaic performance is favorably improved. When the material is applied to a perovskite solar cell to prepare a hole transport layer, the hole extraction capability can be enhanced, and the open-circuit voltage, the filling factor and the photoelectric conversion efficiency of a device can be improved.

Description

Technical Field

[0001] The present invention relates to the field of perovskite solar cells, and particularly to a self-assembled monolayer hole transport material, a hole transport layer and a battery thereof. Background Art

[0002] Inverted (p-i-n junction) perovskite solar cells (PSCs) have attracted great attention due to their low-temperature processability, better compatibility with flexible substrates and tandem device fabrication. However, due to large energy losses, they usually exhibit lower power conversion efficiency (PCE) than traditional (n-i-p) cells. To alleviate this problem, reducing the recombination loss at the interface between the perovskite and the charge-selective layer is crucial. In particular, the hole-selective layer (HSL) plays a key role in affecting the performance of inverted PSCs. It helps to: I) extract holes from the perovskite and transport them to the anode; II) prevent electrons from reaching the anode to avoid recombination; III) act as a template to promote the crystallization of the top perovskite absorber. Therefore, it is necessary to develop better materials to improve the quality of the HSL serving the above functions, thereby further improving the performance of PSCs. At present, many achievements have been made in the development of hole transport layers (HTMs) for inverted PSCs, but the material cost is still high, and it is not suitable for large-scale manufacturing and cannot be used for commercialization.

[0003] Self-assembled monolayer materials (SAM) have the following advantages as HTMs: (1) The synthesis of SAM molecules is simple and the dosage is extremely small, which is beneficial to reducing costs; (2) SAM molecules can be chemically bonded to the substrate, with high stability; (3) SAM thin films can be prepared by methods such as soaking, which is beneficial to realizing high-throughput and low-cost manufacturing; (4) As HTMs, the thickness of SAM thin films is very small, which is beneficial to reducing the series resistance and improving the battery efficiency. Therefore, by developing SAMs with excellent performance through molecular engineering design, it is expected to obtain low-cost and high-efficiency HTMs and promote the commercialization process of PSCs. Summary of the Invention

[0004] In order to overcome the defects of high raw material cost and low performance of known hole transport materials in the prior art, the present invention provides a novel self-assembled monolayer hole transport material, a hole transport layer and a battery thereof. Using the compound of formula I of the present invention as the hole transport material to prepare the hole transport layer ensures the hole transport performance of the material and helps to improve the photovoltaic performance.

[0005] Specifically, the first aspect of the present invention provides a compound represented by the following formula I:

[0006]

[0007] Wherein:

[0008] L is C1-20 Alkyl;

[0009] A is an anchoring group, selected from the structures shown in any one of the following formulas A1 - A5:

[0010]

[0011] -Si(OR3)3 (A5)

[0012] Wherein, * represents the position where A is connected to L;

[0013] R1 is selected from H, C 1-20 Alkyl, C 1-20 Alkoxy, cyano, nitro, amino, halogen, substituted or unsubstituted 6 - 14 - membered aryl;

[0014] R2 is selected from H, C1 - 20 alkyl, C1 - 20 alkoxy, cyano, nitro, amino, halogen, substituted or unsubstituted 6 - 14 - membered aryl;

[0015] Each R3 is independently selected from C1 - 4 alkyl.

[0016] In one or more embodiments, the L is C 1-4 Alkyl.

[0017] In one or more embodiments, the R1 is selected from H, C 1-6 Alkyl, C 1-6 Alkoxy, halogen, and substituted or unsubstituted phenyl.

[0018] In one or more embodiments, the R2 is selected from H, C 1-6 Alkyl, C 1-6 Alkoxy, halogen, and substituted or unsubstituted phenyl.

[0019] In one or more embodiments, R1 and R2 are the same.

[0020] In one or more embodiments, both R1 and R2 are H, both are halogen, both are C 1-4 Alkoxy or both are unsubstituted phenyl.

[0021] In one or more embodiments, each R3 is independently methyl or ethyl.

[0022] In one or more embodiments, all R3 are the same group.

[0023] In one or more embodiments, the formula A5 is:

[0024]

[0025] In one or more embodiments, the compound is selected from the compounds of Formula 1 to 5:

[0026]

[0027]

[0028] The second aspect of the present invention provides a self-assembled monolayer hole transport material, which comprises a Compound of Formula I as described in any one of the embodiments herein.

[0029] In one or more embodiments, the self-assembled monolayer hole transport material is a solution of a Compound of Formula I as described in any one of the embodiments herein and an organic solvent.

[0030] In one or more embodiments, in the solution, the mass-to-volume ratio of the Compound of Formula I to the organic solvent is (0.1 - 5) mg / mL.

[0031] In one or more embodiments, the organic solvent is selected from alcohols, such as one or more of methanol, ethanol, and isopropanol.

[0032] The third aspect of the present invention provides a hole transport layer, and the surface of the hole transport layer has a self-assembled monolayer formed by the Compound of Formula I as described in any one of claims 1 to 5.

[0033] The fourth aspect of the present invention provides a perovskite solar cell, which comprises a conductive base layer, a hole transport layer as described in any one of the embodiments herein, a perovskite layer, an electron transport layer, a cathode buffer layer, and an electrode stacked in sequence.

[0034] The fifth aspect of the present invention provides the use of the Compound of Formula I as described in any one of the embodiments herein in the preparation of a hole transport material with improved transport performance and film-forming quality or in enhancing the hole transport property of a material.

[0035] The sixth aspect of the present invention provides the use of the Compound of Formula I as described in any one of the embodiments herein in the preparation of a hole transport layer in a perovskite solar cell.

[0036] The seventh aspect of the present invention provides the use of the Compound of Formula I as described in any one of the embodiments herein in enhancing the hole transport performance of the hole transport layer in a perovskite solar cell.

[0037] The eighth aspect of the present invention provides the use of the Compound of Formula I as described in any one of the embodiments herein in the preparation of a perovskite solar cell with improved transport performance and photovoltaic performance.

[0038] Advantages of the present invention:

[0039] (1) The compound of formula I provided by the present invention with different anchoring groups can undergo firm self-assembly with the substrate surface through chemical bonding, having good coverage, improving the film-forming quality, and enhancing the transport performance.

[0040] (2) The compound of formula I provided by the present invention, as a hole transport material, has a rigid conjugated large planar fused-ring core structure, ensuring the hole transport performance of the material and contributing to improving the photovoltaic performance.

[0041] (3) The synthesis method of the present invention is simple, with few steps, and the raw materials used are inexpensive and readily available, featuring low cost. Brief Description of the Drawings

[0042] Figure 1 It is a schematic structural diagram of the perovskite solar cell of the present invention.

[0043] 1 - ITO conductive glass; 2 - hole transport layer; 3 - perovskite layer; 4 - electron transport layer; 5 - cathode buffer layer; 6 - silver electrode.

[0044] Figure 2 It is the PL mapping image of the perovskite solar cell prepared in Example 1.

[0045] Figure 3 It is the PL mapping image of the perovskite solar cell prepared in Example 2.

[0046] Figure 4 It is the PL mapping image of the perovskite solar cell prepared in Example 4.

[0047] Figure 5 It is the PL mapping image of the perovskite solar cell prepared in Comparative Example 1.

[0048] Figure 6 It is the PL mapping image of the perovskite solar cell prepared in Comparative Example 2. Detailed Description of the Embodiments

[0049] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned herein. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definitions herein shall prevail.

[0050] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not in any way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0051] In this document, terms such as "comprising", "including", "containing" and similar terms encompass the meanings of "consisting essentially of" and "consisting of". For example, when this document discloses that "A comprises B and C", "A consists essentially of B and C" and "A consists of B and C" should be considered to have been disclosed in this document.

[0052] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0053] In this document, "alkyl" refers to an aliphatic hydrocarbon group, which can be branched or straight-chain. In some embodiments, "alkyl" contains 1 to 20 carbon atoms, i.e., C 1-20 alkyl. Although the current definition also covers the occurrence of the term "alkyl" without a specified numerical range, in this document, whenever a numerical range such as "1 to 20" appears, it refers to each integer within the given range; for example, "1 to 20 carbon atoms" means that the alkyl group consists of 1 carbon atom, 2 carbon atoms, 3 carbon atoms, 4 carbon atoms, 5 carbon atoms, 6 carbon atoms, etc., and contains at most 20 carbon atoms. In some embodiments, the alkyl is C 1-4 alkyl. In one aspect, the alkyl is methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl. Typical alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl or tert-butyl.

[0054] In this document, "alkoxy" refers to an (alkyl)O-group, where the alkyl is as defined herein.

[0055] In this document, "aryl" refers to an aromatic ring composed of carbon atoms, where each atom on the ring is a carbon atom. In some embodiments, the aryl is C6-C 14 aryl, such as C6-C 10 aryl. In one aspect, the aryl is phenyl or naphthyl. In some preferred embodiments, the aryl is phenyl. Depending on the structure, the aryl group can be a monovalent group or a divalent group (i.e., arylene).

[0056] In this document, "halogen" is fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

[0057] In this document, an amino group refers to a group composed of one nitrogen atom and two hydrogen atoms, with the chemical formula -NH2.

[0058] In this document, unless otherwise specified, the percentage refers to the mass percentage and the ratio refers to the mass ratio.

[0059] In this text, when describing embodiments or examples, it should be understood that it is not used to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications, and equivalents of the methods and materials described in the present invention can be covered within the scope defined by the claims.

[0060] In this text, for the sake of brevity of description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0061] The object of the present invention is to provide a self-assembled monolayer hole transport material, a hole transport layer, and a battery thereof. Using the compound of Formula I of the present invention as a hole transport material to prepare a hole transport layer, it undergoes firm self-assembly with the substrate surface through chemical bonding, has good coverage, increases the film-forming quality, and improves the transport performance; the provided molecule has a rigid conjugated large planar fused-ring core structure, ensuring the hole transport performance of the material and contributing to improving the photovoltaic performance.

[0062] In some embodiments, as Figure 1 shown, the perovskite solar cell includes an ITO conductive glass, a hole transport layer, a perovskite layer, an electron transport layer, a cathode buffer layer, and a silver electrode from bottom to top.

[0063] In the present invention, the compound of Formula I has the following structure:

[0064]

[0065] In the formula:

[0066] L is C 1-20 alkyl;

[0067] A is an anchoring group, selected from the structures shown in any one of the following formulas A1 to A5):

[0068]

[0069] -Si(OR3)3 (A5)

[0070] wherein, * represents the position where A is connected to L;

[0071] R1 is selected from H, C 1-20 alkyl, C 1-20 alkoxy, cyano, nitro, amino, halogen, substituted or unsubstituted 6-14-membered aryl;

[0072] R2 is selected from H, C 1-20 alkyl, C 1-20An alkoxy group, a cyano group, a nitro group, an amino group, a halogen, a substituted or unsubstituted 6-14-membered aryl group;

[0073] Each R3 is independently selected from C 1-4 alkyl.

[0074] In some embodiments, L is C 1-4 alkyl.

[0075] In some embodiments, R1 is selected from H, C 1-6 alkyl, C 1-6 alkoxy, halogen, and substituted or unsubstituted phenyl.

[0076] In some embodiments, R2 is selected from H, C1-6 alkyl, C1-6 alkoxy, halogen, and substituted or unsubstituted phenyl. In some embodiments, R1 is the same as R2. In some preferred embodiments, both R1 and R2 are H, both are halogen, both are C1-4 alkoxy, or both are unsubstituted phenyl.

[0077] In some embodiments, each R3 is independently methyl or ethyl. In some embodiments, all R3 are the same group.

[0078] In some preferred embodiments, formula A5 is:

[0079]

[0080] In some embodiments, the compound of formula I can be selected from the compounds of formulas 1 to 5:

[0081]

[0082]

[0083] In the present invention, 1H-phenanthro[1,10,9,8-CDEFG]carbazole can be used as a raw material to prepare the compound of formula I of the present invention. The structural formula of 1H-phenanthro[1,10,9,8-CDEFG]carbazole is shown as formula (1)-1 below:

[0084]

[0085] In some embodiments, the preparation route for preparing the compound of formula I using formula (1)-1 can be that the raw material compound of formula (1)-1 first undergoes a substitution reaction to obtain the following compound of formula (I)-1, and then the compound of (I)-1 is reacted to obtain the compound shown in formula I. The preparation route is as follows:

[0086]

[0087] In some embodiments, the halogenation reaction of 1H-phenanthro[1,10,9,8-CDEFG]carbazole (i.e., the compound of formula (1)-1) can be carried out to obtain the compound of formula (I)-1 in which both R1 and R2 are halogens. In some specific embodiments, 1H-phenanthro[1,10,9,8-CDEFG]carbazole can be halogenated with N-halosuccinimide to obtain the compound of formula (I)-1 in which both R1 and R2 are halogens. In some embodiments, the N-halosuccinimide can be N-bromosuccinimide or N-chlorosuccinimide.

[0088] Further, in some embodiments, the substitution reaction of the compound of formula (I)-1 in which both R1 and R2 are halogens can be continued to substitute R1 and R2 with C 1-20 alkyl, C 1-20 alkoxy, cyano, nitro, amino, substituted or unsubstituted 6-14-membered aryl; thereby obtaining the compound of formula (I)-1 in which R1 and R2 are selected from C 1-20 alkyl, C 1-20 alkoxy, cyano, nitro, amino, substituted or unsubstituted 6-14-membered aryl. In some preferred embodiments, the substitution reaction of the compound of formula (I)-1 in which both R1 and R2 are halogens is carried out to substitute R1 and R2 with C 1-6 alkyl, C 1-6 alkoxy, and substituted or unsubstituted phenyl.

[0089] For example, in some specific embodiments, the substitution reaction of the compound of formula (I)-1 in which both R1 and R2 are halogens and sodium methoxide is carried out to obtain the compound of formula (I)-1 in which R1 and R2 are selected from methoxy.

[0090] For example, in some specific embodiments, the compound of formula (I)-1 in which both R1 and R2 are halogens is reacted with phenylboronic acid, tetrakis(triphenylphosphine)palladium, and potassium carbonate solution to obtain the compound of formula (I)-1 in which R1 and R2 are selected from phenyl.

[0091] In some embodiments, the compound of formula (I)-1 is reacted with NaH and diethyl bromoalkylphosphonate, and after quenching, extraction and concentration under reduced pressure, an organic phase intermediate is obtained; then the organic phase intermediate is reacted with TMSBr (trimethylbromosilane), and methanol and water in sequence to obtain the compound of formula (I) with the above-mentioned A1 structure as the anchoring group. In some specific embodiments, the diethyl bromoalkylphosphonate is diethyl 2-bromoethylphosphonate or diethyl 4-bromobutylphosphonate.

[0092] In some other embodiments, the compound of formula (I)-1 is reacted with NaH and 2-(4-bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, and after quenching, extraction and concentration under reduced pressure, the compound of formula (I) with an anchoring group of structure A2 is obtained.

[0093] In some other embodiments, the compound of formula (I)-1 is reacted with a halo carboxylic acid carboxylate, and after adjusting the pH (to about pH 1.0, such as between 0.8 and 1.2), filtering and recrystallization, the compound of formula (I) with an anchoring group of structure A3 is obtained. In some specific embodiments, the halo carboxylic acid carboxylate is ethyl 3-bromopropionate.

[0094] In some other embodiments, the compound of formula (I)-1 is reacted with an alkylsulfonic acid lactone, and after filtering and recrystallization, the compound of formula (I) with an anchoring group of structure A4 is obtained. In some specific embodiments, the alkylsulfonic acid lactone is butanesultone.

[0095] In some other embodiments, the compound of formula (I)-1 is reacted with NaH and bromoalkyltriethoxysilane, and after quenching, extraction and concentration under reduced pressure, the compound of formula (I) with an anchoring group of structure A5 is obtained. In some specific embodiments, the bromoalkyltriethoxysilane is (3-bromopropyl)triethoxysilane.

[0096] In some specific embodiments, the compound of formula (1) can be prepared by the following method:

[0097] (1) 1H-Phenanthro[1,10,9,8-cdefg]carbazole is reacted with NaH and diethyl 2-bromoethylphosphonate at room temperature, and after adding water for quenching the reaction, extraction and concentration under reduced pressure, the intermediate (1)-2 is obtained:

[0098]

[0099] (2) The intermediate (1)-2 is reacted with TMSBr (trimethylbromosilane), DCM is removed by concentration under reduced pressure, and then methanol and water are added for hydrolysis reaction to obtain the compound of formula (1).

[0100] In some embodiments, the compound of formula (2) can be prepared by a method comprising the following steps:

[0101] (1) 1H-Phenanthro[1,10,9,8-cdefg]carbazole is reacted with NBS (N-bromosuccinimide), and the product is separated by column chromatography to obtain the compound of formula (2)-2:

[0102]

[0103] (2): React the compound of formula (2)-2 with NaH and diethyl 4-bromobutylphosphonate at room temperature, then add water for quenching reaction. After extraction and concentration under reduced pressure, the intermediate (2)-3 is obtained;

[0104]

[0105] (3): React the intermediate (2)-3 with TMSBr (trimethylsilyl bromide), concentrate under reduced pressure to remove DCM, then add methanol and water for hydrolysis reaction to obtain the compound of formula (2).

[0106] In some embodiments, a method comprising the following steps can be used to prepare the compound of formula (3):

[0107] (1) is the same as step 1 in the preparation of the compound of formula (2).

[0108] (2) React the compound of formula (2)-2 with sodium methoxide at room temperature, then add water for quenching reaction. After extraction, concentration under reduced pressure and separation by column chromatography, the intermediate (3)-3 is obtained:

[0109]

[0110] (3): React the intermediate (3)-3 with ethyl 3-bromopropionate, pour it into water and filter; adjust the pH of the filtrate to 1.0 with hydrochloric acid, filter the mixture to obtain the crude product, and after drying and recrystallization (DCM / ethanol), the compound of formula (3) is obtained.

[0111] In some embodiments, a method comprising the following steps can be used to prepare the compound of formula (4):

[0112] (1): is the same as step 1 in the preparation of the compound of formula (2).

[0113] (2): Dissolve the compound of formula (2)-2, phenylboronic acid, tetrakis(triphenylphosphine)palladium, and potassium carbonate solution in toluene, carry out a reflux reaction, filter, concentrate the filtrate under reduced pressure and separate by column chromatography to obtain the intermediate (4)-3:

[0114]

[0115] (3): React the intermediate (4)-3 with NaH and (3-bromopropyl)triethoxysilane at room temperature, then add water for quenching reaction, extract, and concentrate under reduced pressure to obtain the compound of formula (4).

[0116] In some embodiments, a method comprising the following steps can be used to prepare the compound of formula (5):

[0117] (1): 1H-phenanthro[1,10,9,8-CDEFG]carbazole reacts with NCS (N-chlorosuccinimide), and the product is separated by column chromatography to obtain the compound of formula (5)-2:

[0118]

[0119] (2): The compound of formula (5)-2 is reacted with NaH and 2-(4-bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane at room temperature, then water is added for quenching reaction, extraction is carried out, and the mixture is concentrated under reduced pressure to obtain the intermediate (5)-3:

[0120]

[0121] (3): The intermediate (5)-3 is dissolved in a mixed solution of acetone and water, then sodium periodate and ammonium acetate are added, and the reaction is carried out at room temperature. After the reaction is completed, the pH of the filtrate is adjusted to 1.0 with hydrochloric acid, and the crude product is obtained by filtration. The crude product is dried and recrystallized to obtain the product of formula (5) compound.

[0122] In some embodiments, a method including the following steps can be used to prepare the compound of formula (6):

[0123] (1) 1H-phenanthro[1,10,9,8-CDEFG]carbazole, THF (tetrahydrofuran) and sodium hydride are stirred and mixed at a certain temperature, then butanesulfonic acid lactone is added, and the mixture is stirred and reacted after heating. After the reaction is completed, the obtained white solid is filtered, washed with acetone, dried and recrystallized with water to obtain the compound of formula (6).

[0124] The hole transport layer of the present invention can be obtained by preparing the above-mentioned compound of formula (I) by a solution method.

[0125] In some embodiments, the preparation of the hole transport layer of the present invention includes the following steps:

[0126] (1) The compound of formula (I) is dissolved in an organic solvent to obtain a self-assembled monolayer hole transport material solution;

[0127] (2) The self-assembled monolayer hole transport material solution is coated on a substrate layer such as ICO glass and annealed to obtain a hole transport layer.

[0128] In the self-assembled monolayer hole transport material solution, the mass ratio of the compound of formula (I) to the volume of the organic solvent can be (0.1-5) mg / mL, such as 0.4-0.6 mg / mL.

[0129] In the self-assembled monolayer hole transport material solution, the organic solvent can be selected from alcohols, such as one or more of methanol, ethanol and isopropanol.

[0130] In some embodiments, spin coating can be carried out at a rotational speed of 4500 - 5500 rpm. The time for spin coating can be 20 - 40 s.

[0131] In some embodiments, the annealing temperature can be 80 - 120 °C, such as 95 - 105 °C, and the annealing time can be 5 - 15 min, such as 8 - 12 min.

[0132] In some embodiments, the thickness of the hole transport layer is 1 - 50 nm.

[0133] The present invention also includes a perovskite solar cell, which comprises a conductive glass layer, the hole transport layer described herein, a perovskite layer, an electron transport layer, a cathode buffer layer, and an electrode that are stacked. The perovskite solar cell of the present invention can be prepared by conventional methods in the art.

[0134] The conductive glass layer applicable to the present invention can be a conventional conductive glass in the art for preparing perovskite solar cells, such as ICO conductive glass or TCO conductive glass.

[0135] The active material of the perovskite layer applicable to the present invention comprises a first perovskite material and a second perovskite material; wherein, the first perovskite material is selected from at least one of lead halide salts and tin halide salts, and the second perovskite material is selected from at least one of formamidinium halide salts, methylammonium halide salts, and cesium halide salts. In some embodiments, the material of the perovskite absorption layer is lead iodide and methylammonium iodide. There is no particular limitation on the preparation of the perovskite active layer, and conventional methods in the art for preparing perovskite active layers can be used, including but not limited to one or more of spin coating, blade coating, evaporation coating, printing, spraying, spray pyrolysis, and slot coating. The process parameters can be adjusted according to the target thickness of the perovskite absorption layer. In some embodiments, the thickness of the perovskite layer is 450 nm - 650 nm.

[0136] The materials of the electron transport layer applicable to the present invention include but are not limited to one or more of C60, TiO2, ZnO, WO3, SnO2, Zn2SnO4, fullerenes, and their derivatives. There is no particular limitation on the preparation of the electron transport layer, and conventional methods in the art for preparing electron transport layers can be used, including but not limited to one or more of spin coating, spraying, spray pyrolysis, slot coating, and atomic layer deposition. The process parameters can be adjusted according to the target thickness of the electron transport layer. In some embodiments, the thickness of the electron transport layer is 10 nm - 100 nm.

[0137] Materials suitable for the buffer layer of the present invention include, but are not limited to, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), zirconium acetylacetonate, etc. There is no particular limitation on the preparation of the buffer layer, and conventional methods for preparing buffer layers in the art can be used, including but not limited to one or more of spin coating, spraying, spray pyrolysis, slot coating, and atomic layer deposition. Process parameters can be adjusted according to the target thickness of the hole blocking layer. In some embodiments, the thickness of the buffer layer is 1 nm - 10 nm.

[0138] Materials suitable for the electrodes of the present invention can be selected from one or more of silver, copper, conductive oxides, and carbon electrodes. In some embodiments, the thickness of the electrode is 90 nm - 400 nm.

[0139] The present invention also provides the application of the above-mentioned self-assembled monolayer hole transport material in organic light-emitting diodes and organic solar cells. In the present invention, the organic light-emitting diodes and organic solar cells can be conventional in the art.

[0140] The present invention will be described below by way of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, and materials used in the examples are conventional methods, reagents, and materials in the art unless otherwise specified. The starting compounds in the examples can all be obtained through commercial channels.

[0141] Preparation Example 1

[0142] Prepare the compound of formula (1):

[0143]

[0144] Step 1: Dissolve the compound of formula (1)-1 (1H-phenanthro[1,10,9,8-CDEFG]carbazole) in DMF, slowly add it under ice bath conditions, stir for 20 minutes, then add diethyl 2-bromoethylphosphonate, react at room temperature for 12 hours, add water to quench the reaction, and extract with water / dichloromethane. The organic phase is concentrated under reduced pressure to obtain the intermediate (1)-2;

[0145] Step 2: Dissolve the intermediate (1)-2 in DCM (dichloromethane), then add TMSBr (trimethyl bromosilane), stir at room temperature for 12 hours, concentrate under reduced pressure to remove DCM, and then add methanol and water to obtain the final hydrolyzed product, the compound of formula (1).

[0146] Preparation Example 2

[0147] Prepare the compound of formula (2):

[0148]

[0149]

[0150] Step 1: At 0 °C, add the compound of formula (2)-1 to DCM (dichloromethane), then slowly add NBS (N-bromosuccinimide). After restoring to room temperature, continue stirring for 16 hours. The product is separated by column chromatography, and the eluent is PE (polyethylene):DCM = 5:1 to obtain the compound of formula (2)-2;

[0151] Step 2: Dissolve the compound of formula (2)-2 in DMF, then add NaH. After stirring for 30 minutes, add diethyl 4-bromobutylphosphonate. After reacting at room temperature for 24 hours, add water to quench the reaction, and extract with water / dichloromethane. The organic phase is concentrated under reduced pressure to obtain the intermediate (2)-3;

[0152] Step 3: Dissolve the intermediate (2)-3 in DCM, then add TMSBr (trimethylbromosilane). After stirring at room temperature for 12 hours, concentrate under reduced pressure to remove DCM, then add methanol and water to obtain the final hydrolyzed product, the compound of formula (2).

[0153] Preparation Example 3

[0154] Prepare the compound of formula (3):

[0155]

[0156] Step 1: At 0 °C, add the compound of formula (3)-1 to DCM (dichloromethane), then slowly add NBS (N-bromosuccinimide). After restoring to room temperature, continue stirring for 16 hours. The product is separated by column chromatography, and the eluent is PE (polyethylene):DCM = 5:1 to obtain the compound of formula (3)-2;

[0157] Step 2: Dissolve the compound of formula (3)-2 in methanol, then slowly add sodium methoxide. After reacting at room temperature for 24 hours, add water to quench the reaction, and extract with water / dichloromethane. The organic phase is concentrated under reduced pressure;

[0158] Step 3: Dissolve the intermediate (3)-3 in DMF, then add ethyl 3-bromopropionate. Heat to 35 °C and react for 12 hours. Pour into water and filter; adjust the pH of the filtrate to 1.0 with 2M hydrochloric acid. Filter the mixture to obtain the crude product, and after drying, recrystallize (DCM / ethanol) to obtain the product, the compound of formula (3).

[0159] Preparation Example 4

[0160] Prepare the compound of formula (4):

[0161]

[0162] Step 1: At 0 °C, add the compound of formula (4)-1 to DCM (dichloromethane), and then slowly add NBS (N-bromosuccinimide). After restoring to room temperature, continue stirring for 16 hours. The product is separated by column chromatography, and the eluent is PE (polyethylene):DCM = 5:1 to obtain the compound of formula (4)-2;

[0163] Step 2: Dissolve the compound of formula (4)-2, phenylboronic acid, tetrakis(triphenylphosphine)palladium, and potassium carbonate solution in toluene. Under nitrogen protection, reflux at 90 °C for 24 hours. After the reaction is cooled to room temperature, filter. The filtrate is concentrated under reduced pressure and then separated by column chromatography to obtain the intermediate (4)-3;

[0164] Step 3: Dissolve the intermediate (4)-3 in DMF, then add NaH, stir for 30 minutes, and then add (3-bromopropyl)triethoxysilane. React at room temperature for 12 hours, then add water to quench the reaction. Extract with water / dichloromethane, and the organic phase is concentrated under reduced pressure to obtain the compound of formula (4).

[0165] Preparation Example 5

[0166] Prepare the compound of formula (5):

[0167]

[0168] Step 1: At 0 °C, add the compound of formula (5)-1 to DMF, and then slowly add NCS (N-chlorosuccinimide). After restoring to room temperature, continue stirring for 16 hours. The product is separated by column chromatography, and the eluent is PE:DCM = 3:1 to obtain the compound of formula (5)-2;

[0169] Step 2: Dissolve the compound of formula (5)-2 in DMF, then add NaH, stir for 30 minutes, and then add 2-(4-bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. React at room temperature for 16 hours, then add water to quench the reaction. Extract with water / dichloromethane, and the organic phase is concentrated under reduced pressure to obtain the intermediate (5)-3;

[0170] Step 3: Dissolve the intermediate (5)-3 in a mixed solution of acetone and water, then add sodium periodate and ammonium acetate. React at room temperature for 28 hours. After the reaction is completed, adjust the pH of the filtrate to 1.0 with 2M hydrochloric acid, filter the mixture to obtain the crude product, and after drying, recrystallize (DCM / PE) to obtain the product, the compound of formula (5).

[0171] Preparation Example 6

[0172] Prepare the compound of formula (6):

[0173]

[0174] Step 1: At 0 °C, add the compound of formula (6)-1 to THF (tetrahydrofuran), slowly add sodium hydride to the solution, stir for 30 minutes, then add butanesultone, raise the temperature to 70 °C and continue stirring for 12 hours. After the reaction, filter the obtained white solid, wash it with acetone, and dry it for 30 minutes. Then recrystallize it with water to obtain the compound of formula (6).

[0175] Example 1

[0176] S1. Ultrasonically clean the ITO conductive glass successively with deionized water, acetone and isopropanol for 15 min each, and finally place it in a drying oven at 75 °C for drying. Put the dried ITO glass substrate into an ultraviolet ozone machine for 5 min to remove organic impurities on its surface and optimize its surface wettability at the same time;

[0177] S2. Dissolve 1 mg of the compound of formula (1) in 2 mL of ethanol, stir at room temperature until completely dissolved to obtain a self-assembled monolayer hole transport material solution;

[0178] S3. Take 60 μL of the self-assembled monolayer hole transport material solution, drop it on the treated ITO glass, spin-coat it at 5000 rpm for 30 s, and place the ITO glass in step S1 on a hot stage at 100 °C for heat annealing for 10 min to form a hole transport layer;

[0179] S4. Dissolve 722.08 mg of lead iodide and 238.50 mg of iodomethylamine solid in 1 mL of N,N-dimethylformamide (DMF), stir at room temperature until completely dissolved to obtain a perovskite precursor solution;

[0180] S5. In a nitrogen glove box, take 30 μL of the perovskite precursor solution and drop it on the ITO conductive glass forming the hole transport layer. First, spin-coat it at 1000 rpm for 10 s, then spin-coat it at 5000 rpm for 30 s. Quickly add 125 μL of chlorobenzene at 25 s during this process, and then place the ITO glass on a hot stage at 100 °C for heat annealing for 40 min to form a perovskite layer;

[0181] S6. Dissolve PCBM (fullerene derivative) in chlorobenzene with a concentration of 20 mg / ml, stir at 70 °C for 3 - 8 h, spin-coat the PCBM chlorobenzene solution evenly on the perovskite layer at a spin-coating speed of 1500 - 2500 rpm, and obtain an electron transport layer after annealing at 60 °C;

[0182] S7. Subsequently, spin-coat the ethanol solution of BCP (0.5 mg / mL) on the electron transport layer;

[0183] S8. Transfer the ITO conductive glass with the BCP, electron transport layer, perovskite layer, and hole transport layer formed thereon into a vacuum coating instrument. When the vacuum degree reaches 3×10 -4 Pa, evaporate the silver electrode to form a silver electrode with a thickness of 100 nm, obtaining the electrode layer;

[0184] S9. Encapsulate the device with ultraviolet curable resin in a nitrogen glove box to obtain the perovskite solar cell device.

[0185] Example 2

[0186] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound (2).

[0187] Example 3

[0188] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound (3).

[0189] Example 4

[0190] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound (4).

[0191] Example 5

[0192] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound (5).

[0193] Example 6

[0194] The preparation method is the same as that of Example 1, except that: in step S2, 0.2 mg of the compound of formula (1) is dissolved in 2 mL of ethanol, and stirred at room temperature until completely dissolved to obtain the self-assembled monolayer hole transport material solution.

[0195] Example 7

[0196] The preparation method is the same as that of Example 1, except that: in step S2, 10 mg of the compound of formula (1) is dissolved in 2 mL of ethanol, and stirred at room temperature until completely dissolved to obtain the self-assembled monolayer hole transport material solution.

[0197] Example 8

[0198] The preparation method is the same as that of Example 1, except that: the compound of formula (1) in Example 1 is replaced with the compound of formula (6).

[0199] Comparative Example 1

[0200] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound CbzNaph:

[0201]

[0202] Comparative Example 2

[0203] The preparation method is the same as that of Example 1, except that: the hole transport layer material compound (1) is changed to compound 2PACz ((2-(9H-carbazol-9-yl)ethyl)phosphonic acid):

[0204]

[0205] Test Example 1

[0206] The perovskite solar cells prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to optoelectronic tests. The test temperature was 25 ± 1 °C. The current density–voltage curves (J-V curves) of the devices were obtained by a source meter (Keithley 2400) under AM1.5G (100 mW / cm 2 ) illumination provided by a solar simulator (ABET Sun 3000), and the cell area was 0.04907 cm 2 , and the light intensity was calibrated by a standard silicon cell before the test, and the scanning rate was 10 mV / s.

[0207] The open-circuit voltage is the terminal voltage of the battery in the open-circuit state. The short-circuit current density is the current density that the perovskite solar cell can generate under short-circuit conditions. The fill factor is the ratio of the maximum power of the solar cell to the product of the open-circuit voltage and the short-circuit current. The photoelectric conversion efficiency can be calculated by measuring the current density–voltage curves (J-V curves) of the solar cell.

[0208] The results are shown in Table 1 below.

[0209] Table 1. Optoelectronic test results

[0210]

[0211] As can be seen from Table 1, compared with Comparative Examples 1-2, in Example 1, by using the compound of the present invention to prepare the hole transport layer, due to the enhanced hole extraction ability, the loss of the open-circuit voltage is reduced, resulting in an increase in the open-circuit voltage; at the same time, the fill factor and photoelectric conversion efficiency of the device are improved.

[0212] Test Example 2

[0213] The perovskite solar cells prepared in Examples 1, 2, 4 and Comparative Examples 1-2 were subjected to photoluminescence scanning to obtain PL mapping images. Among them,Figure 2 The PL mapping image of the perovskite solar cell prepared in Example 1. Figure 3 The PL mapping image of the perovskite solar cell prepared in Example 2. Figure 4 The PL mapping image of the perovskite solar cell prepared in Example 4. Figure 5 The PL mapping image of the perovskite solar cell prepared in Comparative Example 1. Figure 6 The PL mapping image of the perovskite solar cell prepared in Comparative Example 2. On the other hand, the PL mapping diagram can also show the transport performance of the film. The brighter the film, the better the transport performance.

[0214] The maximum and minimum brightness data in the PL mapping diagrams of Examples 1, 2, 4 and Comparative Examples 1-2 are shown in Table 2 below.

[0215] Table 2. Brightness data values in the PL mapping diagram

[0216] Serial number Minimum value Maximum value Example 1 51190 61450 Example 2 51490 61689 Example 4 50181 61191 Comparative example 1 11968 25046 Comparative example 2 8907 11018

[0217] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. The compound shown in the following formula I: Where: L is C 1-20 alkyl; A is an anchoring group, selected from any of the following structures A1 to A5: -Si(OR3)3(A5) in, * indicates the position where A and L are connected; R1 is selected from H, C 1-20 Alkyl, C 1-20 Alkoxy, cyano, nitro, amino, halogen, substituted or unsubstituted 6-14 membered aryl; R2 is selected from H, C 1-20 Alkyl, C 1-20 Alkoxy, cyano, nitro, amino, halogen, substituted or unsubstituted 6-14 membered aryl; Each R3 is independently selected from C 1-4 alkyl.

2. The compound according to claim 1, characterized in that The L is C 1-4 alkyl.

3. The compound according to claim 1, characterized in that: The R1 is selected from H, C 1-6 Alkyl, C 1-6 Alkoxy, halogen and substituted or unsubstituted phenyl; and / or The R2 is selected from H, C 1-6 Alkyl, C 1-6 Alkoxy, halogen, and substituted or unsubstituted phenyl; Preferably, R1 and R2 are the same; preferably, R1 and R2 are both H, both halogen, both C 1-4 Alkoxy or are all unsubstituted phenyl.

4. The compound according to claim 1, characterized in that Each R3 is independently methyl or ethyl; preferably, all R3 are the same group; preferably, the formula A5 is:

5. The compound according to claim 1, characterized in that The compound is selected from the compounds of formula 1 to 5:

6. A self-assembled monolayer hole transport material, characterized in that: It contains the compound of formula I according to any one of claims 1 to 5.

7. The self-assembled monolayer hole transport material according to claim 6, characterized in that: The self-assembled monolayer hole transport material is a solution containing the compound of formula I and an organic solvent; Preferably, in the solution, the mass ratio of the compound of formula I to the volume ratio of the organic solvent is (0.1-5) mg / mL; Preferably, the organic solvent is selected from alcohols, such as one or more of methanol, ethanol and isopropanol.

8. A hole transport layer, characterized in that: The surface of the hole transport layer has a self-assembled monolayer formed by the compound of formula I according to any one of claims 1 to 5.

9. A perovskite solar cell, characterized in that: The perovskite solar cell comprises a conductive substrate layer, a hole transport layer as claimed in claim 7, a perovskite layer, an electron transport layer, a cathode buffer layer and an electrode which are stacked in sequence. 10.Select from the following applications: Use of the compound of formula I according to any one of claims 1 to 5 in preparing a hole transport material with improved transport performance and film-forming quality or in improving the hole transport property of a material; Use of the compound of formula I according to any one of claims 1 to 5 in preparing a hole transport layer in a perovskite solar cell; Use of the compound of formula I according to any one of claims 1 to 5 in improving the hole transport performance of a hole transport layer in a perovskite solar cell; Use of the compound of formula I according to any one of claims 1 to 5 in the preparation of perovskite solar cells with improved transport performance and photovoltaic performance.

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