Preparation method of hole transport layer of perovskite battery, perovskite battery, hole transport material

Abstract

The present invention discloses a preparation method of a hole transport layer for a perovskite battery, a perovskite battery, and a hole transport material, belonging to the technical field of perovskite batteries. In the present invention, a hole transport layer precursor solution is coated on the surface of a substrate to obtain the hole transport layer; the hole transport layer precursor solution includes self-assembled small molecules, and the self-assembled small molecules include the following structure: #imgabs0#, X includes S, Se or Te; R1 includes hydrogen, halogen, aldehyde group, cyano group, phenyl group, thiophene group, trifluoromethyl group; R2 includes hydrogen, halogen, aldehyde group, cyano group, phenyl group, thiophene group, trifluoromethyl group; L includes alkyl group, phenyl group, naphthyl group, anthracenyl group, thiophene group; A includes: #imgabs1#. Preparing the hole transport layer of the perovskite battery by the above preparation method is beneficial to improving the device performance of the perovskite battery.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite cells, and in particular to a method for preparing a hole transport layer of a perovskite cell, a perovskite cell, and a hole transport material. Background Art

[0002] With the increasing shortage of energy, it is necessary to develop inexhaustible clean energy such as solar energy, and solar cells are one of the most important technologies for utilizing solar energy. Among many solar cells, perovskite cells (PSCs), as the third generation of new cells, have a power conversion efficiency (PCE) that has increased from 3.8% in 2009 to 26.1% that has been certified so far, and have great research value and development prospects for reverse PSCs. In particular, reverse PSCs are more promising for commercial applications due to their ease of fabrication, low hysteresis effect, and excellent stability, and an efficient hole transport layer is an important factor in ensuring the high efficiency and high efficiency of perovskite cells.

[0003] At present, commonly used hole transport materials (HTMs) such as PEDOT:PSS are usually prepared into a hole transport layer precursor solution and then coated on the surface of the substrate to form a hole transport layer. However, due to the acidity of PEDOT:PSS, it will corrode the perovskite material over a long period of time and reduce the stability of the photovoltaic module.

[0004] In order to solve the stability problem, people turned to NiOx as a hole transport material. However, NiOx has multiple oxidation states and is prone to redox reactions with perovskite materials, resulting in voltage loss. In addition, the use of NiOx to prepare a hole transport layer requires high-temperature annealing, which needs to be as high as 300°C or above, which is not conducive to commercial applications. Summary of the invention

[0005] Based on the background technology, the main purpose of the present invention is to provide a method for preparing a hole transport layer of a perovskite cell, a perovskite cell, and a hole transport material.

[0006] To achieve the above object, the present invention provides a method for preparing a hole transport layer of a perovskite battery, comprising the following steps: coating a hole transport layer precursor solution on the surface of a substrate to obtain the hole transport layer; the hole transport layer precursor solution comprises self-assembled small molecules; wherein the self-assembled small molecules comprise the following general structural formula:

[0007]

[0008] In the general structural formula:

[0009] X includes S, Se or Te;

[0010] R1 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl, trifluoromethyl;

[0011] R2 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl, trifluoromethyl;

[0012] L includes alkyl, phenyl, naphthyl, anthracenyl, thienyl;

[0013] A is .

[0014] In some embodiments of the present invention, in the general structural formula, the L includes the alkyl group, the alkyl group includes a C2 alkyl group or a C4 alkyl group; and / or, R1 and R2 are the same.

[0015] In some embodiments of the present invention, the self-assembling small molecule comprises at least one of the following structural formulas:

[0016] , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , 、

[0017] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 , , , .

[0018] In some embodiments of the present invention, the method for preparing the self-assembling small molecule includes method one and method two;

[0019] The method 1 comprises the following steps:

[0020] Preparation of the general formula compound M1: mixing the general formula compound M and diethyl n-bromophosphonate, and subjecting the mixture to a nucleophilic substitution reaction under alkaline conditions provided by an alkaline reagent to generate the general formula compound M1, wherein n in the diethyl n-bromophosphonate is an integer greater than or equal to 1;

[0021] Hydrolysis reaction: the general formula compound M1 and trimethylsilyl bromide are mixed and subjected to a hydrolysis reaction to obtain the self-assembling small molecule;

[0022] The second method comprises the following steps:

[0023] Preparation of the general formula compound M2: the general formula compound M and dibromo-substituted Ar undergo Ullmann reaction under the action of a copper catalyst to obtain the general formula compound M2;

[0024] Preparation of the general formula compound M3: the general formula compound M2 and diethyl phosphite are subjected to coupling reaction under the action of a palladium catalyst to obtain the general formula compound M3;

[0025] Hydrolysis reaction: The general formula compound M3 and trimethylsilyl bromide are mixed to undergo a hydrolysis reaction to obtain the self-assembling small molecule.

[0026] In some embodiments of the present invention, in the step of method 1, the molar ratio of the compound of the general formula M, diethyl n-bromophosphonate and the alkaline agent is 1:(2-5):(2.5-5);

[0027] And / or, the temperature of the nucleophilic substitution reaction is 0-100°C;

[0028] And / or, the time of the nucleophilic substitution reaction is 12h~24h;

[0029] And / or, the molar ratio of the compound of the general formula M1 to trimethylsilyl bromide is 1:10-20;

[0030] And / or, the reaction temperature of the hydrolysis reaction is 20°C to 35°C;

[0031] And / or, the reaction time of the hydrolysis reaction is 12h~24h.

[0032] In some embodiments of the present invention, in the step of the method 2, the molar ratio of the compound of the general formula M to the dibromo-substituted Ar is 1:2-4;

[0033] And / or, the reaction temperature of the Ullmann reaction is 60° C. to 180° C.;

[0034] And / or, the reaction time of the Ullmann reaction is 8h~24h.

[0035] In some embodiments of the present invention, the self-assembled small molecules are dissolved in an organic solvent to obtain the hole transport layer precursor solution; and / or, the coating method includes spin coating; and / or, the hole transport layer precursor solution is annealed after being coated on the surface of the substrate.

[0036] The present invention also provides a perovskite battery, comprising a hole transport layer prepared by the preparation method described above.

[0037] In some embodiments of the present invention, the perovskite cell includes a transparent conductive oxide layer, and the hole transport layer is disposed on a surface of the transparent conductive oxide layer.

[0038] In some embodiments of the present invention, the perovskite cell includes, from bottom to top, a transparent conductive oxide layer, the hole transport layer, a perovskite active layer, an electron transport layer and a back electrode layer.

[0039] The present invention also provides a hole transport material, wherein the hole transport material comprises a self-assembled small molecule, and the self-assembled small molecule comprises the following general structural formula:

[0040]

[0041] In the general structural formula:

[0042] X includes S, Se or Te;

[0043] R1 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl;

[0044] R2 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl;

[0045] L includes alkyl, phenyl, naphthyl, anthracenyl or thienyl;

[0046] A includes .

[0047] The beneficial effects that can be achieved by the present invention are:

[0048] The present invention utilizes self-assembled small molecules to prepare a hole transport layer of a perovskite battery. The self-assembled small molecules have a DAD-type molecular structure, a rigid conjugated plane and a double anchoring group. The double anchoring group can form good contact with a substrate by chemical bonding. The DAD-type molecular structure increases the convenience of charge transfer, and the rigid conjugated plane can promote hole extraction. In addition, the length of the connecting group of the self-assembled molecule is controllable, and the morphology, stacking mode and solubility of the formed film can be optimized by adjusting the length of the connecting group. The self-assembled small molecules are applied to prepare a hole transport layer of a perovskite battery, which is beneficial to improving the device performance of the perovskite battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0050] Figure 1 The figure is a schematic diagram of the preparation process of the compound M of the general formula according to one embodiment of the present invention.

[0051] Figure 2 Schematic diagram of the preparation process of self-assembling small molecules according to an embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the preparation process of self-assembling small molecules according to another embodiment of the present invention.

[0053] Figure 4 Schematic diagram of the structure of a perovskite battery according to an embodiment of the present invention.

[0054] Figure 5 This is a schematic structural diagram of a perovskite battery according to another embodiment of the present invention.

[0055] Figure 6 This is a schematic diagram of the performance data of the perovskite battery in Example 1 of the present invention.

[0056] Figure 7 This is a schematic diagram of the performance data of the perovskite battery in Example 2 of the present invention.

[0057] Figure 8 This is a schematic diagram of the performance data of the perovskite battery in Example 3 of the present invention.

[0058] Fig. 9 It is a schematic diagram of the performance data of the comparative perovskite battery of the present invention.

[0059] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0060] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] In the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0063] The present invention provides a method for preparing a hole transport layer of a perovskite battery, comprising the following steps: coating a hole transport layer precursor solution onto the surface of a substrate to obtain the hole transport layer; the hole transport layer precursor solution comprises self-assembling small molecules.

[0064] Among them, the self-assembling small molecules include the following structural formula:

[0065] ;

[0066] In the general structural formula, X includes S, Se or Te; R1 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl, trifluoromethyl; R2 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl, trifluoromethyl; L includes alkyl, phenyl, naphthyl, anthracenyl, thienyl; A includes

[0067] .

[0068] In some embodiments, L comprises a C2 alkyl group, a C4 alkyl group, a phenyl group, or a naphthyl group.

[0069] In some embodiments, R1 and R2 are the same.

[0070] In some embodiments, the self-assembling small molecule comprises at least one of the following structural formulas:

[0071] , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

[0072] , , , , , , , , , , , , , , , , , 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。

[0073] When preparing the hole transport layer, the hole transport layer precursor solution is coated on the surface of the substrate to obtain the hole transport layer. The hole transport layer precursor solution contains self-assembled small molecules. The self-assembled small molecules have a DAD-type molecular structure, a rigid conjugated plane and a double anchoring group. The double anchoring group can form a good contact with the substrate by chemical bonding. The DAD-type molecular structure increases the convenience of charge transfer, and the rigid conjugated plane can promote hole extraction. In addition, the length of the connecting group of the self-assembled molecule is controllable, and the morphology, stacking mode and solubility of the formed film can be optimized by adjusting the length of the connecting group, which is beneficial to improving the device performance of the perovskite battery.

[0074] The preparation method of the self-assembling small molecule includes method one and method two.

[0075] Method 1 includes the following steps:

[0076] Preparation of the general formula compound M1: mixing the general formula compound M and diethyl n-bromophosphonate, and subjecting the mixture to a nucleophilic substitution reaction under alkaline conditions provided by an alkaline reagent to generate the general formula compound M1, wherein n in the diethyl n-bromophosphonate is an integer greater than or equal to 1;

[0077] Hydrolysis reaction: The general formula compound M1 and trimethylsilyl bromide are mixed and subjected to a hydrolysis reaction to obtain the self-assembling small molecule.

[0078] In the present invention, the compound of formula M can be purchased or prepared by means disclosed in the art. In one embodiment, refer to Figure 1 The preparation of the compound of formula M comprises the following steps:

[0079] S10, the general formula compound A and R1-substituted tributylstannylthiophene are reacted in tetrahydrofuran by still coupling reaction to obtain the general formula compound B. Wherein, X in the general formula compound A is selected from S, Se or Te, and R1 in the R1-substituted tributylstannylthiophene includes at least one of hydrogen, halogen, aldehyde, cyano, phenyl, thienyl, and trifluoromethyl. In this step, the molar ratio of the general formula compound A to the R1-substituted tributylstannylthiophene can be 1: (2-4), the reaction temperature can be the reflux temperature of tetrahydrofuran, and the reaction time is controlled at 12h-24h.

[0080] S20, the general formula compound B undergoes a condensation ring-closing reaction under the catalysis of triphenylphosphine to generate the general formula compound M. In this step, the molar ratio of the general formula compound B to triphenylphosphine can be 1: (10-20), the reaction temperature can be the reflux temperature of o-dichlorobenzene, and the reaction time is controlled at 12h-24h.

[0081] In some embodiments, the compound M has the following structural formula:

[0082] , X includes S, Se or Te, and R1 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl.

[0083] In some embodiments, the compound of formula M has the following structural formula:

[0084] In this embodiment, X in the general formula compound M is an S element, and R1 is hydrogen.

[0085] The steps for preparing the compound of formula M1 in method 1 are explained below.

[0086] In some implementations, the n-bromophosphonic acid diethyl ester includes 2-bromoethyl diethyl phosphate, 4-bromobutyl diethyl phosphonate, or 3-bromopropyl diethyl phosphonate.

[0087] In some embodiments, the alkaline agent comprises sodium hydride (NaH).

[0088] In some embodiments, the compound of formula M, diethyl n-bromophosphonate, and an alkaline agent can be added to an organic solvent to obtain a reaction system, and the temperature is raised to perform a nucleophilic substitution reaction to prepare the compound of formula M1.

[0089] In some embodiments, the organic solvent includes dimethyl sulfoxide (DMSO).

[0090] In some embodiments, the general formula compound M and an alkaline reagent are first added to a reaction container, and then an organic solvent is added after nitrogen is replaced, and diethyl n-bromophosphonate is added dropwise to obtain a reaction system, and then the temperature is raised to perform a nucleophilic substitution reaction to prepare the general formula compound M1.

[0091] In some embodiments, the reaction vessel comprises a two-necked round bottom flask.

[0092] In some embodiments, thin layer chromatography (TLC) is used to monitor the progress and completion of the reaction.

[0093] In some embodiments, after the nucleophilic reaction is monitored to be finished, the reaction is quenched to obtain a reaction system. For example, water is added to the system to quench the reaction.

[0094] In some embodiments, the reaction system obtained by quenching the reaction is subjected to extraction to obtain an organic phase, the organic phase is washed, dried, and filtered to obtain a filtrate, and the filtrate is concentrated and purified to obtain a compound of the general formula M1.

[0095] In some embodiments, the reaction system is extracted with an extractant to obtain an organic phase. For example, the extractant includes ethyl acetate, and extraction can be performed three times to increase the yield of the compound of formula M1.

[0096] In some embodiments, the organic phase obtained by extraction is washed with a detergent. For example, the detergent includes water and brine. The organic phase can be washed with water first and then with brine.

[0097] In some embodiments, the washed organic phase is dried with a desiccant, illustratively, the desiccant comprises anhydrous sodium sulfate.

[0098] In some embodiments, the dried organic phase is filtered to obtain a filtrate which is concentrated by rotary evaporation and then purified by column chromatography to obtain compound M1.

[0099] In some embodiments, the molar ratio of the compound of formula M, diethyl n-bromophosphonate and the alkaline agent is 1:(2-5):(2.5-5), further 1:3:3, and can also be 1:2:2.5, 1:5:5, 1:3:4, etc.

[0100] In some embodiments, the reaction temperature of the nucleophilic substitution reaction is 0-100°C, and can be any value in the range of 0-100°C, such as 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, etc.

[0101] In some embodiments, the reaction time of the nucleophilic substitution reaction is 12 h to 24 h, and can be any value within the range of 12 h to 24 h, such as 12 h, 13 h, 15 h, 18 h, 20 h, 22 h, 24 h, etc.

[0102] The hydrolysis reaction in method 1 is explained below.

[0103] In some embodiments, the molar ratio of the general formula compound M1 to trimethylsilyl bromide is 1:(10-20), and can be any ratio within the range of 1:(10-20), such as 1:10, 1:13, 1:14, 1:15, 1:16, 1:18, 1:20, etc.

[0104] In some embodiments, a reaction solvent is added to a mixed system of the general formula compound M1 and trimethylsilyl bromide to disperse and mix the general formula compound M1 and trimethylsilyl bromide to promote the hydrolysis reaction. The reaction solvent includes at least one of 1,4-dioxane, dichloromethane, and tetrahydrofuran, and 1,4-dioxane includes ultra-dry 1,4-dioxane. Exemplarily, ultra-dry 1,4-dioxane is added to the general formula compound M1, and then trimethylsilyl bromide is slowly added dropwise to perform a hydrolysis reaction to obtain a reactant.

[0105] In some embodiments, the reactants obtained from the hydrolysis reaction are concentrated and filtered to obtain self-assembling small molecules.

[0106] In some embodiments, the concentration and filtration process includes: adding methanol to the reactants, removing excess trimethylsilyl bromide with methanol, then removing part of the solvent in the reactants by rotary evaporation, and then adding distilled water to precipitate solids. The yellow solid obtained by filtration is the self-assembled small molecule of the present invention.

[0107] In some embodiments, the reaction temperature of the hydrolysis reaction is 20°C to 35°C, and can be 20°C, 25°C, 30°C, etc.

[0108] In some embodiments, the reaction time of the hydrolysis reaction in method one is 12 h to 24 h, and can be any value within the range of 12 h to 24 h, such as 12 h, 13 h, 15 h, 18 h, 20 h, 22 h, 24 h, etc.

[0109] In some embodiments, reference Figure 2 , method 1 comprises the following steps:

[0110] Preparation of the general formula compound M1: dispersing the general formula compound M and diethyl n-bromophosphonate in dimethyl sulfoxide (DMSO) provided with alkaline conditions by sodium hydride (NaH), and undergoing a nucleophilic substitution reaction to obtain the general formula compound M1, wherein n in the diethyl n-bromophosphonate includes an integer greater than or equal to 2;

[0111] Hydrolysis reaction: under the condition of room temperature 25±5°C, ultra-dry 1,4-dioxane is added to the general formula compound M1, and then trimethylsilyl bromide is slowly added dropwise to carry out a hydrolysis reaction to obtain a reactant, and the reactant is crystallized under the action of methanol (MeOH) and water to obtain a self-assembled small molecule.

[0112] The self-assembling small molecules can also be prepared by method 2, which includes the following steps:

[0113] Preparation of compound M2: Ullmann reaction of compound M and dibromo-substituted Ar under the action of a copper catalyst to obtain compound M2, wherein Ar includes phenyl, naphthyl, anthracenyl, phenanthryl, thienyl or dithienyl;

[0114] Preparation of the general formula compound M3: the general formula compound M2 and diethyl phosphite are subjected to coupling reaction under the action of a palladium catalyst to obtain the general formula compound M3;

[0115] Hydrolysis reaction: The general formula compound M3 and trimethylsilyl bromide are mixed to undergo a hydrolysis reaction to obtain the self-assembling small molecule.

[0116] The steps for preparing the compound of formula M2 in method 2 are explained below.

[0117] In some embodiments, the molar ratio of the compound of formula M to the dibromo-substituted Ar is 1:(2-4), and can be any ratio within the range of 1:(2-4), such as 1:2, 1:3, 1:4, etc.

[0118] In some embodiments, the copper catalyst includes copper iodide.

[0119] In some embodiments, the reaction time of the Ullmann reaction is 8 h to 24 h, and can be any ratio within the range of 8 h to 24 h, such as 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h, 24 h, etc.

[0120] In some embodiments, the compound of formula M, dibromo-substituted Ar and a copper catalyst are dispersed in an organic solvent, and the Ullmann reaction is carried out under the temperature condition of reflux of the organic solvent.

[0121] In some embodiments, the organic solvent comprises tetrahydrofuran.

[0122] In some embodiments, the compound of formula M, dibromo-substituted Ar and copper catalyst are dispersed in tetrahydrofuran, and the Ullmann reaction is carried out at the reflux temperature of tetrahydrofuran.

[0123] The steps for preparing the compound of formula M3 in method 2 are explained below.

[0124] In some embodiments, the molar ratio of the general formula compound M2 and diethyl phosphite is 1:(2-10), further 1:(2-5), and can be any ratio in the range of 1:(2-10), such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0125] In some embodiments, the palladium catalyst includes at least one of palladium acetate (Pd(OAc)2), palladium acetylacetonate.

[0126] In some embodiments, the general formula compound M2, diethyl phosphite and palladium catalyst are dispersed in an organic solvent, and the coupling reaction is carried out in the reflux of the organic solvent, which is beneficial to promote the reaction, wherein the reaction temperature of the coupling reaction can be the reflux temperature of the organic solvent. For example, when the organic solvent is tetrahydrofuran, the reaction temperature of the coupling reaction is the reflux temperature of tetrahydrofuran.

[0127] In some embodiments, the reaction time of the coupling reaction of the general formula compound M2 and diethyl phosphite in the presence of a palladium catalyst is 8 h to 12 h, for example, 8 h, 9 h, 10 h, 11 h, 12 h, etc.

[0128] In some embodiments, the molar ratio of the general formula compound M3 and trimethylsilyl bromide is 1:(10~30), further 1:(10~20), and can be any value in the range of 1:(10~30), such as 1:10, 1:12, 1:15, 1:18, 1:20, 1:22, 1:25, 1:28, 1:30, etc.

[0129] In some embodiments, an alkaline regulator and a reaction promoter are added to the reaction system in which the general formula compound M2 and diethyl phosphite are coupled under the action of a palladium catalyst. The alkaline regulator includes potassium acetate (KOAc), and the alkaline regulator can adjust the reaction system to alkalinity to promote the reaction; the reaction promoter includes 1,1'-bis(diphenylphosphino)ferrocene (DPPF). 1,1'-bis(diphenylphosphino)ferrocene, as a phosphine ligand, can adjust the chemical environment around the Pd metal center and promote the catalytic cycle.

[0130] The steps of the hydrolysis reaction in method 2 are explained below.

[0131] In some embodiments, the reaction temperature of the hydrolysis reaction of the compound of formula M3 and trimethylsilyl bromide in method 2 is 20°C to 35°C, and can be 20°C, 25°C, 30°C, 35°C, etc.

[0132] In some embodiments, the reaction time of the hydrolysis reaction of the general formula compound M3 and trimethylsilyl bromide in method 2 is 12h~24h, further 12h~16h, and can be any value in the range of 12h~24h, such as 12h, 13h, 15h, 18h, 20h, 22h, 24h, etc.

[0133] In some embodiments, a reaction solvent is added to a mixed system of the general formula compound M3 and trimethylsilyl bromide to disperse and mix the general formula compound M3 and trimethylsilyl bromide to promote the hydrolysis reaction. The reaction solvent includes at least one of 1,4-dioxane, dichloromethane, and tetrahydrofuran, and 1,4-dioxane includes ultra-dry 1,4-dioxane. Exemplarily, ultra-dry 1,4-dioxane is added to the general formula compound M3, and then trimethylsilyl bromide is slowly added dropwise to perform a hydrolysis reaction to obtain a reactant.

[0134] In some embodiments, the reactants obtained from the hydrolysis reaction are concentrated and filtered to obtain self-assembling small molecules.

[0135] In some embodiments, the concentration and filtration process includes: adding methanol to the reactants, removing excess trimethylsilyl bromide with methanol, then removing part of the solvent in the reactants by rotary evaporation, and then adding distilled water to precipitate solids. The yellow solid obtained by filtration is the self-assembled small molecule of the present invention.

[0136] In some implementations, reference Figure 3 , method 2 includes the following steps:

[0137] Preparation of compound M2: The general formula compound M and p-dibromobenzene undergo Ullmann reaction under alkaline conditions provided by K2CO3 and the catalysis of copper iodide in the reflux of dimethylacetamide (DMAc) to obtain the general formula compound M2;

[0138] Preparation of compound M3: catalyst palladium acetate (Pd(OAc)2), potassium acetate (KOAc), 1,1'-bis(diphenylphosphino)ferrocene (DPPF), compound M2 and diethyl phosphite are mixed and dispersed in tetrahydrofuran (THF), and a coupling reaction is carried out in the reflux of tetrahydrofuran (THF) to prepare compound M3;

[0139] Hydrolysis reaction: Under room temperature of 25±5°C, the general formula compound M3 and trimethylsilyl bromide are mixed in 1,4-dioxane (Diox), and a hydrolysis reaction occurs to obtain a reactant, which is crystallized under the action of methanol (MeOH) and water to obtain a self-assembled small molecule.

[0140] In some embodiments, the self-assembling small molecules can be dissolved in an organic solvent to obtain a hole transport layer precursor solution, and then the hole transport layer precursor solution is coated on the surface of the substrate to obtain the hole transport layer.

[0141] In some embodiments, the organic solvent includes isopropyl alcohol.

[0142] In some embodiments, the mass concentration of the self-assembled small molecule dispersion in the hole transport layer precursor solution is 0.75 mg~1 mg / mL.

[0143] In some embodiments, the hole transport layer precursor solution is a self-assembled small molecule, which can be understood as directly coating the self-assembled small molecule onto the surface of the substrate to obtain the hole transport layer.

[0144] In some embodiments, a hole transport layer precursor solution can also be prepared by combining common hole transport materials and self-assembled small molecules in the art. For example, self-assembled small molecules and hole transport material nickel oxide are used together, a nickel oxide layer is first coated on the surface of the substrate, and then self-assembled small molecules are coated on the surface of the nickel oxide layer to form a self-assembled small molecule layer, and the nickel oxide layer and the self-assembled small molecule layer together constitute the hole transport layer.

[0145] In some embodiments, the coating method includes spin coating.

[0146] In some embodiments, the spin coating speed is 3500 rpm to 4000 rpm, and the spin coating time is 25s to 35s, which can be 25s, 30s, 35s, etc.

[0147] In some embodiments, after the hole transport layer precursor solution is coated on the surface of the substrate, an annealing treatment is performed, the annealing temperature is 100° C. to 105° C., and the annealing time is 8 min to 10 min.

[0148] A hole transport film containing self-assembled small molecules is used as a hole transport layer of a perovskite battery, which can improve the device performance of the perovskite battery. Therefore, the present invention further provides a perovskite battery.

[0149] The perovskite battery of the present invention comprises a hole transport layer prepared by the preparation method as described above, and the hole transport layer contains self-assembled small molecules.

[0150] In some embodiments, the perovskite cell includes a transparent conductive oxide layer, and a hole transport layer is prepared on the surface of the transparent conductive oxide layer by the method of the present invention to obtain an inverted perovskite cell. In this embodiment, the hole transport layer is prepared on the surface of the transparent conductive oxide layer, and the double anchor groups of the self-assembled small molecules can form a good contact with the front electrode layer by compound bonding, thereby strengthening the connection between the hole transport layer and the front electrode layer, improving the efficiency of charge transfer, and improving the structural stability and performance stability of the perovskite cell.

[0151] In some embodiments, a perovskite active layer is also prepared on the surface of the hole transport layer of the perovskite cell. The perovskite active layer can be prepared by referring to the methods disclosed in the art.

[0152] In some embodiments, reference Figure 4 The perovskite cell includes, from bottom to top, a transparent conductive oxide layer, a hole transport layer of the present invention, a perovskite active layer, an electron transport layer and a back electrode layer.

[0153] In some embodiments, other functions may be provided between the hole transport layer and the perovskite active layer, between the perovskite active layer and the electron transport layer, and between the electron transport layer and the back electrode layer. For example, a hole blocking layer may be provided between the electron transport layer and the back electrode layer.

[0154] The self-assembled small molecule of the present invention can be used as a hole transport material in the field of perovskite cells, and can be used to prepare a hole transport layer of a perovskite cell. Therefore, the present invention also provides a hole transport material, which includes the self-assembled small molecule, and the self-assembled small molecule includes the following general structural formula:

[0155]

[0156] In the general structural formula:

[0157] X includes S, Se or Te;

[0158] R1 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl;

[0159] R2 includes hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl;

[0160] L includes alkyl, phenyl, naphthyl, anthracenyl or thienyl;

[0161] A includes .

[0162] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0163] Example 1

[0164] Example 1: Prepare a self-assembling small molecule (I-1) by method 1.

[0165] Preparation of general formula compound M1: Add general formula compound M (1.632 g, 5 mmol) and sodium hydride (mass concentration of 60%, 0.6 g, 15 mmol) to a 100 mL double-necked round-bottom flask, replace nitrogen, add 20 mL of dimethyl sulfoxide (DMSO), stir at room temperature 30±5°C for 30 min, then slowly add 2-bromoethyl diethyl phosphate (15 mmol) dropwise, heat the system to 80°C for 18 h and analyze by thin layer chromatography (TL C) Monitor the progress of the reaction. When the reaction is complete, add 50 mL of water to the system to quench the reaction, extract three times with ethyl acetate (30 mL×3), combine the organic phases, wash the organic phases with water (30 mL×3) and saturated brine (30 mL), dry with anhydrous sodium sulfate and filter to obtain a filtrate. The filtrate is concentrated by rotary evaporation and purified by column chromatography to obtain a yellow viscous liquid, which is the general formula compound M1, marked as the general formula compound M1-1 (yield 86%).

[0166] Hydrolysis reaction: Add the general formula compound M1-1 (4.0 mmol) to a 100 mL three-necked round-bottom flask, replace the nitrogen, add 30 mL of ultra-dry 1,4-dioxane, and then slowly drop trimethylsilyl bromide (TMSBr) (5.4 mL, 40.0 mmol) therein, and react at room temperature of 30±5°C for 24 h to obtain the reactant. Add 10 mL of methanol dropwise to the reactant, continue stirring for 2 h, remove part of the solvent by rotary evaporation, and then add 20 mL of distilled water to precipitate the solid, and filter to obtain a yellow solid (yield 78%), which is the self-assembled small molecule, marked as self-assembled small molecule I-1.

[0167] The structural formulas of the general formula compound M in Example 1, the prepared general formula compound M1-1 (n=2), and the self-assembling small molecule I-1 are as follows:

[0168] , , .

[0169] Example 2

[0170] Example 2 refers to method 1 of Example 1 to prepare a self-assembling small molecule, except that in the step of preparing the general formula compound M1 in Example 2, 15 mmol of 4-bromobutylphosphonic acid diethyl ester is used to replace the 2-bromoethyl phosphate diethyl ester in Example 1 to prepare the general formula compound M1-2 with a yield of 92%, and then, in the step of preparing the self-assembling small molecule, 4.0 mmol of the general formula compound M1-2 is used to replace the general formula compound M1-1 in Example 1 to prepare a self-assembling small molecule with a yield of 82%, which is marked as self-assembling small molecule I-2.

[0171] The structural formulas of the general compound M1-2 (n=4) and the self-assembling small molecule I-2 prepared in Example 2 are as follows:

[0172] , .

[0173] Example 3

[0174] Example 3: The self-assembling small molecule I-3 was prepared by method 2.

[0175] Preparation of general formula compound M2: Compound M (4.0 mmol), 1,4-dibromobenzene (8.0 mmol), cuprous iodide (2.0 mmol), potassium carbonate (10.0 mmol) were added to a 100 mL three-necked round-bottom flask, and 30 mL of dimethylacetamide was added thereto after replacing nitrogen. After the addition, the system was heated to reflux for 18 h and the reaction was monitored by thin layer chromatography (TLC). After the reaction was detected to be complete, 50 mL of water was added to the system to quench the reaction, and ethyl acetate (30 mL×3) was used for extraction three times, and the organic phases were combined. After the organic phases were washed with water (30 mL×3) and brine (30 mL), they were dried with anhydrous sodium sulfate and filtered to obtain a filtrate. The filtrate was concentrated by rotary evaporation and purified by column chromatography to obtain a yellow solid, which was general formula compound M2 (yield 86%).

[0176] Preparation of general formula compound M3: Add general formula compound M2 (3.0mmol), palladium acetate (0.15mmol), 1,1'-bis(diphenylphosphino)ferrocene (0.3mmol), potassium acetate (0.6mmol) to a 100mL three-necked round-bottom flask, replace nitrogen and add 30mL of tetrahydrofuran, after addition, heat the system to reflux for 12h and monitor by thin layer chromatography (TLC). After the reaction is detected to be complete, add 50mL of water to the system to quench the reaction, extract three times with ethyl acetate (30mL×3), combine the organic phases, wash the organic phases with water (30mL×3) and saturated brine (30mL), dry with anhydrous sodium sulfate and filter to obtain a filtrate, the filtrate is concentrated by rotary evaporation and purified by column chromatography to obtain a yellow viscous liquid, which is general formula compound M3 (yield 82%).

[0177] Hydrolysis reaction: Add the general formula compound M3 (4.0 mmol) to a 100 mL three-necked round-bottom flask, replace the nitrogen, add 30 mL of ultra-dry 1,4-dioxane, and then slowly drop trimethylsilyl bromide (TMSBr) (5.4 mL, 40.0 mmol) therein, and react at room temperature 25±5°C for 24 h to obtain the reactant. Add 10 mL of methanol dropwise to the reactant, continue stirring for 2 h, remove part of the solvent by rotary evaporation, and then add 20 mL of distilled water to precipitate the solid, filter to obtain a yellow solid (yield 78%), i.e., a self-assembled small molecule, marked as self-assembled small molecule I-3.

[0178] The structural formulas of the general compound M3 and the self-assembling small molecule I-3 prepared in Example 3 are as follows:

[0179] , .

[0180] Applications of self-assembling small molecules

[0181] The self-assembled small molecules obtained in Examples 1 to 3 are applied to prepare perovskite batteries. The preparation steps of the perovskite batteries are as follows:

[0182] The ITO glass was ultrasonically cleaned with detergent, deionized water, and isopropanol for 30 min in sequence, dried with nitrogen, and then treated with ozone for 30 min.

[0183] The I-1 solution, I-2 solution, and I-3 solution (solvent is isopropanol) with a concentration of 0.75 mg / mL were spin-coated on ITO (4000 rpm, 30 s) and annealed at 100°C for 10 min to obtain a hole transport layer;

[0184] Spin coat 1.5 M perovskite precursor solution Cs on the surface of the hole transport layer. 0.05 (FA0.95 MA 0.05 ) 0.95 (I 0.95 Br 0.05 )3, and then thermally annealing at 100°C for 30 min to obtain a perovskite active layer;

[0185] The fullerene derivative (PCBM) solution prepared by chlorobenzene is spin-coated onto the surface of the perovskite active layer to form an electron transport layer;

[0186] 8 nm thick 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was evaporated on the surface of the electron transport layer and annealed at 100°C for 10 min to obtain a hole blocking layer;

[0187] A 10 nm thick silver electrode was evaporated on the surface of the hole blocking layer to obtain a perovskite cell. The corresponding devices obtained in Examples 1 to 3 are numbered I-1, I-2, and I-3, respectively.

[0188] At the same time, a comparative example was set up. In the comparative example, nickel oxide was used as the hole transport layer material. 20 mg / ml nickel oxide aqueous dispersion was spin-coated on ITO at a rotation speed of 4000 rpm, and thermal annealing was performed at 100° C. for 10 min. The corresponding device number was nickel oxide.

[0189] The perovskite cells prepared in Examples 1 to 3 and the comparative example are composed of ITO glass, hole transport layer, perovskite active layer, electron transport layer, hole blocking layer and silver electrode layer from bottom to top.

[0190] Performance Testing

[0191] Under the irradiation of standard sunlight (AM 1.5G), the perovskite cells prepared in Examples 1 to 3 and the comparative example were tested for device performance. The current density-voltage curve of the perovskite cell is shown in FIG. Figures 6 to 9 The data are summarized in Table 1.

[0192] Table 1

[0193]

[0194] In the preparation of the hole transport layer of the perovskite battery, the present invention adds a self-assembling small molecule to the hole transport layer precursor solution. The phosphonic acid group in the self-assembling small molecule can react with the hydroxyl group on the ITO surface to make the self-assembling molecule anchored on the ITO substrate through bidentate and part of the tridentate binding mode, so that a dense and periodic assembly layer is formed on the ITO substrate, the interface contact is optimized, the energy level alignment is adjusted, the hole transport is promoted, and the short-circuit current and fill factor are improved. In addition, the di-PO3H2 can react with Pb 2+ Chelation, at the bottom of the perovskite with FA +(formamidinium ion) forms hydrogen bonds, effectively passivates buried interface defects, inhibits non-radiative recombination, and improves the performance of inverted perovskite cells. The hole transport layer of the inverted perovskite cell prepared by the preparation method of the present invention can obtain a photoelectric conversion efficiency of >20%, which has broad application prospects.

[0195] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a hole transport layer of a perovskite battery, characterized in that: The method comprises the following steps: coating a hole transport layer precursor solution onto the surface of a substrate to obtain the hole transport layer; The hole transport layer precursor solution includes self-assembling small molecules; The self-assembling small molecule has the following structural formula: In the general structural formula: X is S, Se or Te; R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; R2 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; L is a C2 alkyl group, a C4 alkyl group, a phenyl group, a naphthyl group, an anthracenyl group, a thienyl group, a phenanthrenyl group or a dithienyl group; A is .

2. The method for preparing a hole transport layer of a perovskite battery according to claim 1, characterized in that: The self-assembling small molecule is at least one of the following structural formulas: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 3. The method for preparing a hole transport layer of a perovskite battery according to claim 1, characterized in that: The preparation method of the self-assembling small molecule includes method one and method two; The method 1 comprises the following steps: Preparation of the general formula compound M1: The general formula compound M and diethyl n-bromophosphonate are mixed, and a nucleophilic substitution reaction occurs under alkaline conditions provided by an alkaline reagent to generate the general formula compound M1, wherein the diethyl n-bromophosphonate has the following structure: ， The n in the structure of the n-diethyl bromophosphonate is selected from an integer greater than or equal to 2; Hydrolysis reaction: the general formula compound M1 and trimethylsilyl bromide are mixed and subjected to a hydrolysis reaction to obtain the self-assembling small molecule; The second method comprises the following steps: Preparation of a compound of the general formula M2: the compound of the general formula M and a dibromo-substituted Ar undergo an Ullmann reaction under the action of a copper catalyst to obtain a compound of the general formula M2, wherein the Ar is selected from phenyl, naphthyl, anthracenyl, phenanthryl, thienyl or dithienyl; Preparation of the general formula compound M3: the general formula compound M2 and diethyl phosphite are subjected to coupling reaction under the action of a palladium catalyst to obtain the general formula compound M3; Hydrolysis reaction: the general formula compound M3 and trimethylsilyl bromide are mixed to undergo a hydrolysis reaction to obtain the self-assembling small molecule; The general compound M has the following general structural formula: , X is S, Se or Te, R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; The general compound M1 has the following structural formula: , X is S, Se or Te, R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; The general compound M2 has the following structural formula: , X is S, Se or Te, R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; The general compound M3 has the following structural formula: , X is S, Se or Te, R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; The dibromo-substituted Ar has the following structural formula: , the structural formula Ar is phenyl, naphthyl, anthracenyl, phenanthryl, thienyl or dithienyl.

4. The method for preparing a hole transport layer for a perovskite battery according to claim 3, characterized in that: In the step of the method 1, the molar ratio of the compound of the general formula M, diethyl n-bromophosphonate and the alkaline agent is 1:(2-5):(2.5-5); And / or, the temperature of the nucleophilic substitution reaction is 0-100°C; And / or, the time of the nucleophilic substitution reaction is 12h~24h; And / or, the molar ratio of the compound of the general formula M1 to trimethylsilyl bromide is 1:10-20; And / or, the reaction temperature of the hydrolysis reaction is 20°C to 35°C; And / or, the reaction time of the hydrolysis reaction is 12h~24h.

5. The method for preparing a hole transport layer for a perovskite battery according to claim 4, characterized in that: In the step of the second method, the molar ratio of the compound of the general formula M to the dibromo-substituted Ar is 1:2-4; And / or, the reaction temperature of the Ullmann reaction is 60° C. to 180° C.; And / or, the reaction time of the Ullmann reaction is 8h~24h.

6. The method for preparing a hole transport layer for a perovskite battery according to any one of claims 1 to 5, characterized in that: The self-assembling small molecules are dissolved in an organic solvent to obtain the hole transport layer precursor solution; And / or, the coating method includes spin coating; And / or, the hole transport layer precursor solution is further annealed after being coated on the surface of the substrate.

7. A perovskite battery, characterized in that: The perovskite cell comprises a hole transport layer prepared by any one of the preparation methods described in claims 1 to 6.

8. The perovskite cell according to claim 7, characterized in that: The perovskite cell includes a transparent conductive oxide layer, and the hole transport layer is arranged on the surface of the transparent conductive oxide layer.

9. The perovskite cell according to claim 8, characterized in that: The perovskite cell includes, from bottom to top, a transparent conductive oxide layer, a hole transport layer, a perovskite active layer, an electron transport layer and a back electrode layer.

10. A hole transport material, characterized in that: The hole transport material includes a self-assembled small molecule, and the self-assembled small molecule has the following structural formula: In the general structural formula: X is S, Se or Te; R1 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; R2 is hydrogen, halogen, aldehyde, cyano, phenyl, thienyl or trifluoromethyl; L is a C2 alkyl group, a C4 alkyl group, a phenyl group, a naphthyl group, an anthracenyl group or a thienyl group; A is .

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