Hole transport material, preparation method thereof and perovskite solar cell

Abstract

The application relates to a hole transport material, a preparation method thereof and a perovskite solar cell. The hole transport material has a structure as shown in general formula (a), wherein R1 is selected from C3-C6 alkylene; R2 is selected from C1-C6 alkoxy or C1-C6 alkylthio at each occurrence. Therefore, the hole transport layer of the perovskite solar cell prepared by using the hole transport material provided by the application can improve photoelectric performance, enhance cell stability and reduce cell preparation cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, and in particular to a hole transport material, a preparation method thereof and a perovskite solar cell. BACKGROUND

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

[0003] Currently, HTMs in perovskite solar cells are mainly divided into three categories: inorganic HTMs, organic small molecule HTMs and organic polymer HTMs. Among them, organic small molecule HTMs have a clear structure and molecular weight, have the advantages of simple synthesis method, adjustable structure, high purity and easy solution processing, and have become the most common HTMs in perovskite solar cells. Organic small molecule HTMs can be roughly divided into linear structure, spiro structure and star structure according to the spatial structure, and can be divided into dithienopyrrole type, triphenylamine type, carbazole type, biferroce type and thiophene type according to the groups contained in the molecular structure. In order to improve the efficiency of the cell, P-type dopants and interfacial modifiers and other additives are usually added when using traditional organic small molecule HTMs to prepare a hole transport layer, but the introduction of additives will have a negative impact on the stability of the cell, thereby limiting the industrial application of perovskite solar cells. SUMMARY

[0004] Therefore, it is necessary to provide a hole transport material, a preparation method thereof and a perovskite solar cell to overcome the problem that P-type dopants and interfacial modifiers and other additives need to be added when using traditional organic small molecule HTMs to prepare a hole transport layer, resulting in a decrease in the stability of the cell.

[0005] The above-mentioned purpose of the present application is achieved by the following technical solutions:

[0006] In a first aspect, the present application provides a hole transport material having a structure as shown in general formula (a):

[0007] (a);

[0008] wherein R1is selected from C3-C6alkylene;

[0009] R2is independently at each occurrence selected from C1-C6alkoxy or C1-C6alkylthio.

[0010] In one embodiment, R1is selected from C4alkylene;

[0011] R2is independently at each occurrence selected from C1-C3alkoxy or C1-C3alkylthio.

[0012] In one embodiment, R1is selected from -(CH2)4-;

[0013] R2is independently at each occurrence selected from methoxy or methylthio.

[0014] In a second aspect, the present application provides a method for preparing a hole transport material, comprising the following steps:

[0015] subjecting a phenoxazine compound having a structure as shown in general formula (b) and a dihalogenated hydrocarbon having a structure as shown in general formula (c) to a first substitution reaction to prepare a first intermediate having a structure as shown in general formula (d);

[0016] subjecting the first intermediate and triethyl phosphite to an esterification reaction to prepare a second intermediate having a structure as shown in general formula (e);

[0017] subjecting the second intermediate and a diphenylamine compound having a structure as shown in general formula (f) to a second substitution reaction to prepare a third intermediate having a structure as shown in general formula (g);

[0018] subjecting the diethyl phosphonate group on the third intermediate to hydrolysis to form a phosphonic acid group to prepare the hole transport material;

[0019] (b); (c); (d);

[0020] (e); (f);

[0021] (g);

[0022] wherein X and Y are independently at each occurrence selected from halogen;

[0023] R1is selected from C3-C6alkylene;

[0024] R2is independently selected at each occurrence from C1-C6alkoxy or C1-C6alkylthio.

[0025] In one embodiment, R1is selected from C4-C5alkylene;

[0026] R2is independently selected at each occurrence from C1-C3alkoxy or C1-C3alkylthio.

[0027] In one embodiment, R1is selected from -(CH2)4;

[0028] R2is independently selected at each occurrence from methoxy or methylthio.

[0029] In one embodiment, the molar ratio of the phenoxazine compound to the dihaloalkane is 1 : (140-160).

[0030] In one embodiment, the first substitution reaction is performed under basic conditions.

[0031] In one embodiment, the catalyst for the first substitution reaction includes tetrabutylammonium bromide.

[0032] In one embodiment, the temperature for the first substitution reaction is 60-80°C for a time period of 6-18h.

[0033] In one embodiment, the molar ratio of the first intermediate to the triethyl phosphite is 1 : (140-160).

[0034] In one embodiment, the esterification reaction is performed under inert gas protection.

[0035] In one embodiment, the temperature for the esterification reaction is 130-150°C for a time period of 8-16h.

[0036] In one embodiment, the molar ratio of the second intermediate to the diphenylamine compound is 1 : (2-3).

[0037] In one embodiment, the second substitution reaction is performed under basic conditions and inert gas protection.

[0038] In one embodiment, the catalyst for the second substitution reaction includes palladium acetate and tri-tert-butylphosphine.

[0039] In one embodiment, the temperature for the second substitution reaction is 80-90°C for a time period of 6-12h.

[0040] In one of the embodiments, the catalyst for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group includes trimethylsilyl bromide.

[0041] In one of the embodiments, the temperature for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group is 10-40℃, and the time is 10-30h.

[0042] In one of the embodiments, the quenching reagent for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group includes methanol.

[0043] In a third aspect, the present application provides a perovskite solar cell, which comprises an electrically conductive substrate, a first carrier transport layer, a perovskite layer, a second carrier transport layer and a metal electrode arranged in sequence.

[0044] The first carrier transport layer or the second carrier transport layer is a hole transport layer, and the raw material of the hole transport layer comprises the hole transport material as described above, or the raw material of the hole transport layer is prepared by the preparation method of the hole transport material as described above.

[0045] The present application has at least the following beneficial effects:

[0046] The hole transport material (HTM) provided by the present application takes a phenoxazine group as the core, and the P, O or S elements in the molecular structure thereof have a strong interaction with metal elements such as Pb in the perovskite material. Without adding additives such as P-type dopants or interface modifiers, the HTM can passivate grain boundary defects and interface defects, can improve the photoelectric conversion efficiency of the battery, and can ensure the stability of the battery. Meanwhile, the HTM has a deep HOMO energy level matched with the perovskite, has a good hole mobility, is conducive to the extraction and transmission of holes, is conducive to the improvement of the photoelectric conversion efficiency of the battery, and has repeatability. Meanwhile, the HTM has a high decomposition temperature and good thermal stability, and can stably exist under an annealing process.

[0047] In addition, in the preparation process of the trans perovskite solar cell, a perovskite precursor solution is usually coated on the hole transport layer to form a perovskite layer, and the conventional organic small molecule HTM has poor resistance to the perovskite precursor solution, so that there are always pinhole defects on the hole transport layer, which affects the battery efficiency. The HTM provided by the present application has good resistance to the perovskite precursor solution, has good film-forming property itself, is not prone to pinhole defects after forming the perovskite layer, and has good wettability between the perovskite precursor solution after film formation, which is conducive to the crystallization and film formation of the perovskite layer, thereby improving the photoelectric conversion efficiency of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1A structural schematic diagram of a transverse perovskite solar cell in an embodiment;

[0049] Figure 2 A synthetic route map of a hole transport material of Example 1;

[0050] Figure 3 A synthetic route map of a hole transport material of Example 2;

[0051] Figure 4 A TGA curve of a hole transport material of Examples 1-2;

[0052] Figure 5 A current density-voltage curve of three hole transport materials.

[0053] Reference numerals: conductive substrate 100, hole transport layer 200, perovskite layer 300, electron transport layer 400, and metal electrode 500. DETAILED DESCRIPTION

[0054] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the specific embodiments of the present application are described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many different ways other than those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, and thus the present application is not limited to the specific embodiments disclosed below.

[0055] In addition, the terms "first", "second", etc. are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0057] In the present application, the meaning of "at least one" is one or more, such as one, two, and more than two. The meaning of "a plurality" or "several" is at least two, such as two, three, and the like. The meaning of "a plurality of" is at least two, such as two, three, and the like, unless specifically limited otherwise. In the description of the present application, the meaning of "several" is at least one, such as one, two, and the like, unless specifically limited otherwise.

[0058] When a numerical range is disclosed herein, the range is to be construed as continuous, and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when the range is of integers, every integer between the minimum and maximum values is included. In addition, when multiple ranges are provided to describe a characteristic or a property, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood as including any and all sub-ranges subsumed therein.

[0059] If not specifically stated, all steps of the present application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0060] In the present application, "above" or "below" includes the present number. For example, 1 below includes 1.

[0061] In the present application, the temperature parameter, unless specifically limited, allows for constant temperature treatment, and also allows for fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy range controlled by the instrument. Fluctuations within a range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0062] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: (1) 23°C ± 2°C; (2) 25°C ± 5°C; (3) 20°C ± 5°C.

[0063] Terminology

[0064] Unless otherwise stated or contradictory, the terms or phrases used in the present application have the following meanings:

[0065] In the present application, when substituents of the same designation occur more than one time in the general formula, each substituent can be the same or different. As when a general formula contains multiple R, the R can be the same or different.

[0066] "Alkyl" refers to a saturated hydrocarbon radical of a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof, which loses one hydrogen atom to form a monovalent radical. Alkyl groups can represent straight chain, branched chain, and / or cyclic alkyl groups. The number of carbons in an alkyl group can be 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Phrases containing this term, for example, "C1to C9alkyl" means an alkyl group containing 1 to 9 carbon atoms, each occurrence can be independently C1alkyl, C2alkyl, C3alkyl, C4alkyl, C5alkyl, C6alkyl, C7alkyl, C8alkyl, or C9alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1 -propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1 -butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1 -propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1 -butyl (-CH2CH2CH(CH3)2), 2-methyl-1 -butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3, octyl (-(CH2)7CH3).

[0067] "Alkylene" refers to a hydrocarbon radical derived by removal of a hydrogen atom from an alkyl group, which has two monovalent radical centers. It can be a saturated branched alkyl group or a saturated straight chain alkyl group. For example, "C1-C9 alkylene" refers to an alkyl moiety containing 1-9 carbon atoms, which can be independently C1 alkylene, C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene, C8 alkylene, or C9 alkylene at each occurrence. Suitable examples include, but are not limited to: methylene (-CH2-), 1,1-ethyl (-CH(CH3)-), 1,2-ethyl (-CH2CH2-), 1,1-propyl (-CH(CH2CH3)-), 1,2-propyl (-CH2CH(CH3)-), 1,3-propyl (-CH2CH2CH2-), and 1,4-butyl (-CH2CH2CH2CH2-).

[0068] "Alkoxy" refers to a radical having the formula -O-alkyl, i.e., an alkyl group as defined above attached to the parent structure through an oxygen atom. Phrases containing this term, e.g., "C1-C9 alkoxy," refer to an alkyl moiety containing 1-9 carbon atoms, which can be independently C1 alkoxy, C4 alkoxy, C5 alkoxy, C6 alkoxy, C7 alkoxy, C8 alkoxy, or C9 alkoxy at each occurrence. Suitable examples include, but are not limited to: methoxy (-O-CH3 or -O-Me), ethoxy (-O-CH2CH3 or -O-Et), and t-butoxy (-O-C(CH3)3 or -O-t-Bu).

[0069] "Alkylthio" refers to a radical having the formula -S-alkyl, i.e., an alkyl group as defined above attached to the parent structure through a sulfur atom. Phrases containing this term, e.g., "C1-C9 alkylthio," refer to an alkyl moiety containing 1-9 carbon atoms, which can be independently C1 alkylthio, C4 alkylthio, C5 alkylthio, C6 alkylthio, C7 alkylthio, C8 alkylthio, or C9 alkylthio at each occurrence. Suitable examples include, but are not limited to: methylthio (-S-CH3 or -S-Me), ethylthio (-S-CH2CH3 or -S-Et), and t-butylthio (-S-C(CH3)3 or -S-t-Bu).

[0070] "Halogen" refers to F, Cl, Br, or I.

[0071] In a first aspect, the present application provides a hole transport material to overcome the problem of the decline in battery stability caused by the need to add P-type dopants and interface modifiers and other additives when preparing a hole transport layer using conventional organic small molecule HTMs.

[0072] In some embodiments, the hole transport material has a structure as shown in general formula (a):

[0073] (a);

[0074] wherein R1 is selected from C3-C6 alkylene;

[0075] R2 is independently selected at each occurrence from C1-C6 alkoxy or C1-C6 alkylthio.

[0076] The hole transport material (HTM) provided by the present application takes a phenoxazine group as the core. The P, O or S elements in the molecular structure of the HTM have a strong interaction with the metal elements such as Pb in the perovskite material. Without adding P-type dopants or interface modifiers or other additives, the HTM can passivate the grain boundary defects and interface defects, improve the photoelectric conversion efficiency of the battery, and ensure the stability of the battery. Meanwhile, the HTM has a deep HOMO energy level that matches the perovskite, has a good hole mobility, is conducive to the extraction and transmission of holes, is conducive to the improvement of the photoelectric conversion efficiency of the battery, and has repeatability. Meanwhile, the HTM has a high decomposition temperature and good thermal stability, and can stably exist under the annealing process.

[0077] In addition, in the preparation process of the trans perovskite solar cell, a perovskite precursor solution is usually coated on the hole transport layer to form a perovskite layer. The conventional organic small molecule HTM has poor resistance to the perovskite precursor solution, resulting in the existence of pinhole defects on the hole transport layer, which in turn affects the battery efficiency. The HTM provided by the present application has good resistance to the perovskite precursor solution, has good film-forming property itself, is not prone to pinhole defects after the formation of the perovskite layer, and has good wettability between the perovskite precursor solution and the film after film formation, which is conducive to the crystallization and film formation of the perovskite layer, thereby improving the photoelectric conversion efficiency of the battery.

[0078] Optionally, R1 is selected from C3-C6 alkylene, for example, C3 alkylene, C4 alkylene, C5 alkylene and C6 alkylene. Further optionally, R1 is selected from C4 alkylene, for example, -(CH2)4-, -CH2C(CH3)2-, -CH2CH(CH3)CH2-, -CH(CH3)CH2CH2- and -CH(CH3)CH(CH3)-. Still further optionally, R1 is selected from -(CH2)4-.

[0079] It can be understood that R1 is selected from flexible alkylene chains with a suitable chain length, such as C3-C6 alkylene, which is conducive to improving the solubility of the hole transport material. If R1 is selected from C1-C2 alkylene, the phenoxazine compound does not react with the dihalogenated hydrocarbon, and the synthesis is difficult. If R1 is selected from C7 alkylene or alkylene with more carbon atoms, the conductivity of the hole transport material will be reduced, which is not conducive to the extraction and transmission of holes.

[0080] Optionally, each occurrence of R2is independently selected from C1-C6alkoxy or C1-C6alkylthio, for example, C1alkoxy, C2alkoxy, C3alkoxy, C4alkoxy, C5alkoxy, C6alkoxy, C1alkylthio, C2alkylthio, C3alkylthio, C4alkylthio, C5alkylthio, and C6alkylthio. Further optionally, each occurrence of R2is independently selected from C1-C3alkoxy or C1-C3alkylthio, for example, -O-CH3, -O-CH2CH3, -O-CH2CH2CH3, -O-CH(CH3)2, -S-CH3, -S-CH2CH3, -S-CH2CH2CH3, and -S-CH(CH3)2. Still further optionally, each occurrence of R2is independently selected from methoxy (-O-CH3) or methylthio (-S-CH3).

[0081] It is appreciated that, when R2is independently selected from C1-C6alkoxy or C1-C6alkylthio, the O element or S element in R2interacts with metal elements such as Pb in the perovskite material, thereby passivating the grain boundary defects and interface defects without adding additives such as P-type dopants or interface modifiers.

[0082] Optionally, the hole transport material has a structure as shown in general formula (a-1) or general formula (a-2):

[0083] (a-1);

[0084] (a-2).

[0085] Optionally, the hole transport material has a decomposition temperature ≥ 330 °C, for example, 330 °C, 335 °C, 340 °C, 345 °C, 350 °C, 355 °C, 360 °C, 365 °C, 370 °C, 380 °C, 390 °C, and 400 °C. Further optionally, the hole transport material has a decomposition temperature of 330 °C to 350 °C.

[0086] In a second aspect, the present application provides a preparation method of a hole transport material.

[0087] In some embodiments, the preparation method of the hole transport material comprises the following steps:

[0088] S11: subjecting the phenoxazine compound and the dihalogenated hydrocarbon to a first substitution reaction to prepare a first intermediate;

[0089] S12: subjecting the first intermediate and triethyl phosphite to an esterification reaction to prepare a second intermediate;

[0090] S13: subjecting the second intermediate and the diphenylamine compound to a second substitution reaction to prepare a third intermediate;

[0091] S14: hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group to produce the hole transport material.

[0092] The method for producing the hole transport material is described in detail below in a step-by-step manner.

[0093] S11: subjecting a phenoxazine compound having a structure as shown in general formula (b) and a dihalogenated hydrocarbon having a structure as shown in general formula (c) to a first substitution reaction to produce a first intermediate having a structure as shown in general formula (d);

[0094] (b); (c); (d).

[0095] It is understood that the imino group (-NH-) on the phenoxazine compound and the halogen (-Y) on the dihalogenated hydrocarbon will undergo the first substitution reaction, i.e., the N-alkylation reaction, to produce the first intermediate.

[0096] Optionally, X and Y are each independently selected from halogen at each occurrence, such as F, CI, Br, and I. Further optionally, X and Y are each independently selected from Br at each occurrence.

[0097] Optionally, R1is selected from C3-C6alkylene, such as C3alkylene, C4alkylene, C5alkylene, and C6alkylene. Further optionally, R1is selected from C4alkylene, such as -(CH2)4-, -CH2C(CH3)2-, -CH2CH(CH3)CH2-, -CH(CH3)CH2CH2-, and -CH(CH3)CH(CH3)-. Yet further optionally, R1is selected from -(CH2)4-.

[0098] Optionally, the molar ratio of the phenoxazine compound and the dihalogenated hydrocarbon is 1 : (140-160), such as 1 : 140, 1 : 142, 1 : 145, 1 : 148, 1 : 150, 1 : 152, 1 : 155, 1 : 158, and 1 : 160.

[0099] Optionally, the first substitution reaction is performed under basic conditions. Specifically, the basic conditions for the first substitution reaction are adjusted by adding a first base reagent, and the first base reagent includes one or more of LiOH, NaOH, KOH, Na2CO3, K2CO3, NaHCO3, KHCO3, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, and potassium tert-butoxide, further optionally KOH.

[0100] Optionally, the molar ratio of the phenoxazine compound and the first base reagent is 1: (7-10), for example, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, and 1:10.

[0101] Optionally, the catalyst of the first substitution reaction comprises tetrabutylammonium bromide (TBAB); the molar ratio of the phenoxazine compound and the tetrabutylammonium bromide is 1: (0.08-0.12), for example, 1:0.08, 1:0.09, 1:0.10, 1:0.11, and 1:0.12, and further optionally 1:0.1.

[0102] Optionally, the temperature of the first substitution reaction is 60-80°C, for example, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C, and 80°C, and further optionally 65°C; the time of the first substitution reaction is 6-18h, for example, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, and 18h, and further optionally 12h.

[0103] Optionally, after the first substitution reaction, the method further comprises the following step: purifying the first mixture containing the first intermediate. Specifically, the purifying the first mixture comprises the following steps: washing the first mixture with a saturated NaCl solution to prevent the emulsification and layering of the organic phase, and to increase the polarity of the aqueous phase, reduce the solubility of the organic matter in water, and avoid the loss of product yield; extracting the organic phase in the first mixture with dichloromethane; drying the organic phase with a drying agent (such as anhydrous Na2SO4 or anhydrous MgSO4), removing the drying agent by filtration, removing the organic solvent by reduced pressure distillation or rotary evaporation, and further purifying by silica gel chromatography (i.e., silica gel column chromatography), thereby obtaining the first intermediate.

[0104] S12: performing an esterification reaction on the first intermediate and triethyl phosphite to prepare a second intermediate having a structure as shown in general formula (e);

[0105] (e).

[0106] It can be understood that the structure of triethyl phosphite is P(OCH2CH3)3 or P(OEt)3, which does not react with the halogen on the benzene ring, but reacts with the halogen on the hydrocarbon group, i.e., P(OEt)3 reacts with -R1-Y on the first intermediate to generate the second intermediate containing a diethyl phosphonate group through esterification.

[0107] Optionally, the molar ratio of the first intermediate and triethyl phosphite is 1:(140~160), such as 1:140, 1:142, 1:145, 1:148, 1:150, 1:152, 1:155, 1:158 and 1:160.

[0108] Optionally, the esterification reaction is carried out under protection of an inert gas. Specifically, the inert gas comprises one or more of N2, He, Ne, Ar, Kr and Xe, and is further optionally N2.

[0109] Optionally, the esterification reaction is carried out at a temperature of 130℃~150℃, such as 130℃, 132℃, 135℃, 138℃, 140℃, 142℃, 145℃, 148℃ and 150℃, and is further optionally 140℃; and for a time period of 8h~16h, such as 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h and 16h, and is further optionally 12h.

[0110] Optionally, after the esterification reaction, the method further comprises the following step: purifying the second mixture containing the second intermediate. Specifically, purifying the second mixture comprises the following steps: washing the second mixture with saturated NaCl solution, and extracting the organic phase in the second mixture with dichloromethane; drying the organic phase with a drying agent (such as anhydrous Na2SO4 or anhydrous MgSO4), removing the drying agent by filtration, and removing the organic solvent by reduced pressure distillation or rotary evaporation to obtain the second intermediate. Further, the second intermediate can be further purified by recrystallization, for example, by dissolving the second intermediate in dichloromethane and recrystallizing in ethanol or methanol.

[0111] S13: subjecting the second intermediate and a diphenylamine compound having a structure as shown in general formula (f) to a second substitution reaction to prepare a third intermediate having a structure as shown in general formula (g);

[0112] (f); (g).

[0113] It can be understood that the imino group (-NH-) on the diphenylamine compound and the halogen (-X) on the second intermediate will undergo a second substitution reaction, i.e. an N-alkylation reaction, to generate the third intermediate.

[0114] Optionally, each occurrence of R2is independently selected from the group consisting of C1-C6alkoxy or C1-C6alkylthio, for example, C1alkoxy, C2alkoxy, C3alkoxy, C4alkoxy, C5alkoxy, C6alkoxy, C1alkylthio, C2alkylthio, C3alkylthio, C4alkylthio, C5alkylthio, and C6alkylthio. Further optionally, each occurrence of R2is independently selected from the group consisting of C1-C3alkoxy or C1-C3alkylthio, for example, -O-CH3, -O-CH2CH3, -O-CH2CH2CH3, -O-CH(CH3)2, -S-CH3, -S-CH2CH3, -S-CH2CH2CH3, -S-CH(CH3)2. Still further optionally, each occurrence of R2is independently selected from methoxy (-O-CH3) or methylthio (-S-CH3).

[0115] Optionally, the molar ratio of the second intermediate and the diphenylamine compound is 1:(2-3), for example, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, and 1:3.0, further optionally 1:2.2.

[0116] Optionally, the second substitution reaction is performed under basic conditions and protection of an inert gas. Specifically, the inert gas includes one or more of N2, He, Ne, Ar, Kr, and Xe, further optionally N2. The basic conditions of the second substitution reaction are adjusted by the addition of a second base reagent, and the second base reagent includes one or more of LiOH, NaOH, KOH, Na2CO3, K2CO3, NaHCO3, KHCO3, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, and potassium tert-butoxide, further optionally sodium tert-butoxide (Na-O-t-Bu).

[0117] Optionally, the molar ratio of the second intermediate and the second base reagent is 1:(0.8-1.2), for example, 1:0.8, 1:0.9, 1:1.0, 1:1.1, and 1:1.2, further optionally 1:1.

[0118] Optionally, the second substitution reaction is performed in the presence of an organic solvent, for example, 1,4-dioxane, tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF), and n-hexane, further optionally toluene. Optionally, the mass-to-volume ratio of the second intermediate to the organic solvent is 0.015 g / mL-0.025 g / mL.

[0119] Optionally, the catalyst for the second substitution reaction comprises palladium acetate ((CH3COO)2Pd or Pd(OAc)2) and tri-tert-butylphosphine (P(t-Bu)3); the molar ratio of the second intermediate to palladium acetate is 1:(0.04-0.06), for example, 1:0.04, 1:0.045, 1:0.05, 1:0.055, and 1:0.06, and further optionally 1:0.05; the molar ratio of the second intermediate to tri-tert-butylphosphine is 1:(0.08-0.12), for example, 1:0.08, 1:0.09, 1:0.1, 1:0.11, and 1:0.12, and further optionally 1:0.1.

[0120] Optionally, the temperature for the second substitution reaction is 80-90°C, for example, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, and 90°C, and further optionally 85°C. The time for the second substitution reaction is 6-12h, for example, 6h, 7h, 8h, 9h, 10h, 11h, and 12h, and further optionally 12h.

[0121] Optionally, after the second substitution reaction, the method further comprises the following step: purifying the third mixture containing the third intermediate. Specifically, purifying the third mixture comprises the following steps: washing the third mixture with a saturated NaCl solution, and extracting the organic phase in the third mixture with dichloromethane; drying the organic phase with a drying agent (such as anhydrous Na2SO4 or anhydrous MgSO4), removing the drying agent by filtration, removing the organic solvent by reduced pressure distillation or rotary evaporation, and further purifying the third intermediate by silica gel chromatography (i.e., silica gel column chromatography).

[0122] S14: hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group, to prepare a hole transport material.

[0123] It can be understood that the reaction of hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group is a hydrolysis reaction.

[0124] Optionally, the hydrolysis reaction is performed in the presence of an organic solvent, for example, 1,4-dioxane, tetrahydrofuran (THF), toluene, N,N-dimethylformamide (DMF), and n-hexane, and further optionally 1,4-dioxane. Optionally, the mass-volume ratio of the third intermediate to the organic solvent is 0.1-0.2 g / mL.

[0125] Optionally, the catalyst for the hydrolysis reaction comprises trimethylsilyl bromide ((CH3)3SiBr); the molar ratio of the third intermediate and the trimethylsilyl bromide is 1: (8-12), for example, 1:8, 1:9, 1:10, 1:11, 1:12, and further optionally 1:10.

[0126] Optionally, the temperature for the hydrolysis reaction is 10-40°C, for example, 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 38°C and 40°C, and further optionally 20-30°C; the time for the hydrolysis reaction is 10-30h, for example, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h and 30h, and further optionally 12h.

[0127] Optionally, the quenching reagent for the hydrolysis reaction is methanol. Specifically, after the hydrolysis reaction, the following steps are further included: removing the organic solvent by reduced pressure distillation or rotary evaporation to obtain a first crude product; dissolving the crude product in methanol, adding deionized water drop by drop, and stirring at 10-40°C for 8-16h; filtering, and washing the filter cake with deionized water to obtain a second crude product.

[0128] Optionally, after the quenching of the hydrolysis reaction, the following steps are further included: purifying the second crude product by recrystallization. Specifically, purifying the second crude product by recrystallization comprises the following steps: dissolving the second crude product in tetrahydrofuran (THF) and reprecipitating in acetone, filtering to obtain the hole transport material.

[0129] In a third aspect, the present application provides a perovskite solar cell, comprising a conductive substrate, a first carrier transport layer, a perovskite layer, a second carrier transport layer and a metal electrode which are sequentially stacked;

[0130] The first carrier transport layer or the second carrier transport layer is a hole transport layer, and the raw material of the hole transport layer comprises the hole transport material as described above, or the raw material of the hole transport layer is prepared by the preparation method of the hole transport material as described above.

[0131] It can be understood that when the first carrier transport layer is a hole transport layer, the second carrier transport layer is an electron transport layer, i.e. the perovskite solar cell is a reverse structure; when the second carrier transport layer is a hole transport layer, the first carrier transport layer is an electron transport layer, i.e. the perovskite solar cell is a forward structure.

[0132] Please refer to Figure 1 which is a structural schematic diagram of a reverse perovskite solar cell in an embodiment. As shown in Figure 1As shown, the trans-faimass solar cell includes an electrically conductive substrate 100, a hole transport layer 200, a perovskite layer 300, an electron transport layer 400 and a metal electrode 500 which are sequentially stacked.

[0133] Optionally, the material of the electrically conductive substrate 100 is a transparent conductive oxide (TCO), such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), indium zinc tin oxide (IZTO) and indium gallium zinc tin oxide (IGZTO). Further optionally, the material of the electrically conductive substrate 100 is ITO.

[0134] Optionally, the material of the perovskite layer 300 includes an ABX3-type perovskite material. Wherein A is selected from one or more of methylamine, formamidinium, cesium, rubidium, potassium and sodium, B is selected from one or more of lead, tin, germanium, silver and bismuth, and X is selected from one or more of chlorine, bromine and iodine. Further optionally, the material of the perovskite layer 300 is methylammonium lead iodide (MAPbI3).

[0135] Optionally, the material of the electron transport layer 400 includes one or more of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 4,7-diphenyl-1,10-phenanthroline (Bphen), titanium dioxide, tin dioxide, zinc oxide and a fullerene derivative, wherein the fullerene derivative includes indene-C 60 bisadduct (ICBA), [6,6]-phenyl-C 61 methyl butyrate (PC 61 BM) and [6,6]-phenyl-C 71 methyl butyrate (PC 70 BM). Further optionally, the material of the electron transport layer 400 is PC 61 BM.

[0136] Optionally, the material of the metal electrode 500 includes one or more of gold, silver, copper, aluminum and chromium. Further optionally, the material of the metal electrode 500 includes gold and chromium.

[0137] In some embodiments, the method for preparing the trans-faimass solar cell includes the following steps:

[0138] S21: pre-treating the electrically conductive substrate 100;

[0139] Specifically, the pretreatment of the conductive substrate 100 includes the following steps: sequentially ultrasonic cleaning the conductive substrate 100 with deionized water, acetone and ethanol for 15-20 min, and blowing the surface residual solvent with a N2 gas gun; etching or activating by 10-15 min of oxygen plasma treatment, and then transferring the conductive substrate 100 to a N2 gas glove box.

[0140] S22: forming a hole transport layer 200 on the conductive substrate 100;

[0141] Specifically, the preparation method of the hole transport layer 200 includes the following steps: dissolving the hole transport material as described above in chlorobenzene, the mass-volume ratio of the hole transport material and chlorobenzene being 3-15 mg / mL, to obtain a precursor solution; uniformly dropping the precursor solution onto the conductive substrate 100, spin coating at a speed of 4000-5000 rpm for 20-30 s, and annealing at 90-110°C for 10 min, and cooling to room temperature, to form the hole transport layer 200.

[0142] S23: forming a perovskite layer 300 on the hole transport layer 200;

[0143] Specifically, the preparation method of the perovskite layer 300 includes the following steps: dissolving lead iodide, methylammonium chloride and 3-bromobenzyl ammonium iodide (or 3-chlorobenzyl ammonium iodide) in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to obtain a perovskite precursor solution; preheating the structure prepared in step S22 at 130-140°C for 3-5 min, taking 50 μL of the perovskite precursor solution to cover the hole transport layer 200, spin coating at a speed of 3000-5000 rpm for 20-30 s, and annealing at 90-100°C for 10 min, and cooling to room temperature, to form the perovskite layer 300.

[0144] S24: forming an electron transport layer 400 on the perovskite layer 300;

[0145] Specifically, the preparation method of the electron transport layer 400 includes the following steps: taking 40 μL of PC 61 The BM solution is covered on the perovskite layer 300, spin coated at a speed of 1000 rpm for 20-30 s, and annealed at 70°C for 10 min, to form the electron transport layer 400.

[0146] S25: forming a metal electrode 500 on the electron transport layer 400;

[0147] Specifically, the preparation method of the metal electrode 500 comprises the following steps: placing the structure prepared in step S24 in a vacuum evaporation box, and evaporating a 6-nm-thick Cr layer and an 80-nm-thick Au layer on the electron transport layer 400 in sequence to form the metal electrode 500.

[0148] In a fourth aspect, the application provides a stacked battery, comprising a bottom battery and a top battery.

[0149] The bottom battery is a crystalline silicon solar cell.

[0150] The top battery is a perovskite solar cell as described above.

[0151] In a fifth aspect, the application provides a photovoltaic module, comprising a first encapsulation panel, a first encapsulation adhesive film, a battery string, a second encapsulation adhesive film and a second encapsulation panel arranged in sequence, and the battery string is formed by electrically connecting a plurality of perovskite solar cells as described above or a plurality of stacked batteries as described above.

[0152] The application will be further described in detail below in combination with specific examples.

[0153] In the following specific examples and comparative examples, the raw materials used, unless otherwise specified, are commercially available products; the instruments used, unless otherwise specified, are commercially available products; and the processes used, unless otherwise specified, are routinely selected by those skilled in the art.

[0154] Example 1

[0155] See Figure 2 which is a synthetic route map of the hole transport material of the present example. Among them, compound 1 is a phenoxazine compound, compound 2 is a first intermediate, compound 3 is a second intermediate, compound 4 is a diphenylamine compound, and compound 5 is a third intermediate. The obtained product is recorded as 4PAPOZ-OMeDPA.

[0156] The preparation method of the hole transport material of the present example is specifically as follows:

[0157] (1) Synthesis of the first intermediate: In a 100 mL two-necked flask, dibromobutane (20 mL) was added, and the phenoxazine compound (0.93 g, 2.72 mmol) and tetrabutylammonium bromide (0.32 g, 0.27 mmol) were dissolved in the dibromobutane, followed by dropwise addition of an aqueous potassium hydroxide solution (5 mL, 50% by mass). The reaction system was heated to 65°C, and stirred overnight (reaction time: about 12 h). The reaction was quenched with water to obtain a first mixture. The organic phase of the first mixture was extracted with dichloromethane, and the organic phase was combined with anhydrous MgS04for drying, followed by removal of the organic solvent using a rotary evaporator. Further purification was performed using silica gel column chromatography, using petroleum ether and dichloromethane (10:1 by volume) as the eluent, to obtain the first intermediate (0.83 g) at a yield of 65%.

[0158] (2) Synthesis of the second intermediate: In a 100 mL two-necked flask, the first intermediate (1.42 g, 3.0 mmol) and triethyl phosphite (10 mL) were added. The reaction system was heated to 145°C, and stirred overnight (reaction time: about 12 h) under N2protection to obtain a second mixture. The organic phase of the second mixture was extracted with dichloromethane, and the organic phase was combined with anhydrous MgS04for drying, followed by removal of the organic solvent using a rotary evaporator, to obtain the second intermediate (1.01 g, 1.82 mmol) at a yield of 60%.

[0159] (3) Synthesis of the third intermediate: In a 100 mL two-necked flask, the second intermediate (1.09 g, 2.0 mmol), diphenylamine compound (1.00 g, 4.4 mmol), sodium tert-butoxide (0.24 g, 2.5 mmol), palladium acetate (21 mg, 0.09 mmol), a toluene solution of tri-tert-butylphosphine (0.3 mL, 10% by mass), and toluene (60 mL) were added under N2protection. The reaction system was heated to 85°C, and cooled to room temperature after reaction for 12 h to obtain a third mixture. The third mixture was washed with a saturated NaCl solution, and the organic phase was extracted with dichloromethane, and the organic phase was combined with anhydrous MgS04for drying. After filtration, further purification was performed using silica gel column chromatography, using petroleum ether and dichloromethane (6:1 by volume) as the eluent, to obtain the third intermediate (1.26 g, 1.5 mmol) at a yield of 74%.

[0160] (4) Synthesis of hole transport material 4PAPOZ-OMeDPA: add the third intermediate (1.69 g, 2 mmol) and anhydrous 1,4-dioxane (10 mL) into a 100 mL two-necked flask, drop in trimethylsilyl bromide (3.06 g, 20 mmol), and then stir overnight at room temperature (the reaction time is about 12 h); remove 1,4-dioxane by a rotary evaporator to obtain the first crude product in solid state; dissolve the first crude product in quenching reagent methanol (10 mL), then drop in deionized water drop by drop, and stir for 12 h at room temperature; filter and wash the filter cake with deionized water to obtain the second crude product; dissolve the second crude product in THF (5 mL) and re-precipitate in acetone (20 mL), filter to obtain the hole transport material 4PAPOZ-OMeDPA (1.45 g) with a yield of 85%.

[0161] Example 2

[0162] See Figure 3 , which is a synthesis route map of the hole transport material of the present embodiment. Among them, compound 1 is a phenoxazine compound, compound 2 is the first intermediate, compound 3 is the second intermediate, compound 6 is a diphenylamine compound, compound 7 is the third intermediate, and the obtained product is recorded as 4PAPOZ-SMeDPA.

[0163] The preparation method of the hole transport material of the present embodiment is specifically as follows:

[0164] (1) Synthesis of the first intermediate: the same as in Embodiment 1.

[0165] (2) Synthesis of the second intermediate: the same as in Embodiment 1.

[0166] (3) Synthesis of the third intermediate: under the protection of N2, add the second intermediate (1.09 g, 2.0 mmol), the diphenylamine compound (1.15 g, 4.4 mmol), sodium tert-butoxide (0.24 g, 2.5 mmol), palladium acetate (21 mg, 0.09 mmol), a toluene solution of tri-tert-butyl phosphine (0.3 mL, 10% by mass fraction), and toluene (60 mL) into a 100 mL two-necked flask; heat the reaction system to 85°C, cool to room temperature after 12 h of reaction to obtain the third mixture; wash with saturated NaCl solution, and dry the organic phase of the third mixture with anhydrous MgSO4; after filtration, further purify by silica gel column chromatography, and use petroleum ether and dichloromethane in a volume ratio of 6:1 as the eluent to obtain the third intermediate (1.27 g, 1.4 mmol) with a yield of 73%.

[0167] (4) Synthesis of hole transport material 4PAPOZ-SMeDPA: The third intermediate (1.81 g, 2 mmol) and anhydrous 1,4-dioxane (10 mL) were added to a 100 mL double-necked flask, and trimethylbromosilane (3.06 g, 20 mmol) was added dropwise. The mixture was then stirred overnight at room temperature (reaction time was about 12 h). 1,4-dioxane was removed by rotary evaporator to obtain the first crude product in solid form. The first crude product was dissolved in methanol (10 mL) as a quenching agent, and then deionized water was added dropwise. The mixture was stirred at room temperature for 12 h. The mixture was filtered, and the filter cake was washed with deionized water to obtain the second crude product. The second crude product was dissolved in THF (5 mL) and then precipitated in acetone (20 mL). After filtration, the hole transport material 4PAPOZ-SMeDPA (1.46 g) was obtained with a yield of 84%.

[0168] Comparative Example

[0169] The hole transport material in this comparative example is PTTA, namely poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine].

[0170] Test Example

[0171] Thermogravimetric analysis (TGA) was performed on 4PAPOZ-OMeDPA and 4PAPOZ-SMeDPA respectively. The results are shown in [Figure number missing]. Figure 4 .Depend on Figure 4 It can be seen that the thermal decomposition temperature of 4PAPOZ-OMeDPA is 340.4℃ and that of 4PAPOZ-SMeDPA is 292.6℃, indicating good thermal stability, and they can remain stable under annealing processes.

[0172] The aforementioned hole transport material is used to fabricate the hole transport layer of an inverted perovskite solar cell. The specific method for fabricating the inverted perovskite solar cell is as follows:

[0173] (1) Use deionized water, acetone and ethanol to ultrasonically clean the conductive substrate 100 (ITO glass substrate) for 15 min to 20 min in sequence, and use N2 gas gun to blow dry the residual solvent on the surface; etch or activate by oxygen plasma treatment for 10 min to 15 min, and then transfer the conductive substrate 100 to N2 gas glove box.

[0174] (2) Dissolve the hole transport material in chlorobenzene, with a mass-to-volume ratio of 7 mg / mL for both the hole transport material and chlorobenzene, to obtain a precursor solution; uniformly drop the precursor solution onto the conductive substrate 100, spin coat at 3000 rpm for 30 s, anneal at 90°C for 10 min, and cool to room temperature to form a hole transport layer 200.

[0175] (3) Take lead iodide, methylammonium chloride and 3-bromobenzyl ammonium iodide, dissolve in DMF / DMSO mixed solvent to obtain perovskite precursor solution; the structure prepared in step (2) is preheated at 130°C-140°C for 3-5 min, 50 μL of perovskite precursor solution is covered on the hole transport layer 200, and is spin-coated at a speed of 3000 rpm-5000 rpm for 20 s-30 s, and is annealed at 90°C-100°C for 10 min, and is cooled to room temperature to form a perovskite layer 300.

[0176] (4) Take 40 μL of PC 61 BM solution with a concentration of 15 mg / mL is covered on the perovskite layer 300, and is spin-coated at a speed of 1000 rpm for 20 s-30 s, and is annealed at 70°C for 10 min to form an electron transport layer 400.

[0177] (5) The structure prepared in step (4) is placed in a vacuum evaporation box, and a 6 nm thick Cr layer and an 80 nm thick Au layer are sequentially evaporated on the electron transport layer 400 to form a metal electrode 500.

[0178] The performance of the trans-perovskite solar cell (hereinafter referred to as device) is tested by the following method: the power of the solar simulator is adjusted to 100 MW / cm 2 to simulate the radiation standard of AM 1.5G, the current and voltage values of the device are read by connecting the computer of the Keithley 2450 power meter, and the current density-voltage curve is obtained, and the results are shown in Table 1 and Figure 5 . Before the current density-voltage curve measurement, the light intensity is calibrated using a Newport standard silicon cell 91150, and the device adopts a positive and negative scanning mode with a scanning rate of 0.05 V / s.

[0179] As shown in Table 1, the conventional hole transport material PTAA is selected, the open circuit voltage of the corresponding device is 1.1 V, the short circuit current is 20.71 mA / cm 2 , the fill factor is 75.12%, and the photoelectric conversion efficiency is 18.51%.

[0180] The hole transport material 4PAPOZ-OMeDPA of Example 1 is selected, the open circuit voltage of the corresponding device is 1.21 V, the short circuit current is 20.53 mA / cm 2 , the fill factor is 77.35%, and the photoelectric conversion efficiency is 19.36%.

[0181] The hole transport material 4PAPOZ-SMeDPA of Example 2 is selected, the open circuit voltage of the corresponding device is 1.21 V, the short circuit current is 20.51 mA / cm 2The fill factor is 77.54%, and the photoelectric conversion efficiency is 19.47%.

[0182] As shown in Table 1 and Figure 5 It can be seen that the hole transport material of the present application can improve the open circuit voltage and fill factor of the perovskite solar cell without using P-type dopant or interface modifier and other additives, and obtain higher photoelectric conversion efficiency.

[0183] Table 1. Comparison of electrical properties of trans perovskite solar cells

[0184]

[0185] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0186] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A hole transporting material, characterized by, having a structure as shown in general formula (a-2):

2. A method for producing a hole transporting material, characterized by, comprising the following steps: subjecting a phenoxazine compound having a structure as shown in general formula (b) and a dihalogenated hydrocarbon having a structure as shown in general formula (c) to a first substitution reaction to prepare a first intermediate having a structure as shown in general formula (d); subjecting the first intermediate and triethyl phosphite to an esterification reaction to prepare a second intermediate having a structure as shown in general formula (e); subjecting the second intermediate and a diphenylamine compound having a structure as shown in general formula (f) to a second substitution reaction to prepare a third intermediate having a structure as shown in general formula (g); hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group to prepare the hole transport material; wherein X and Y are each independently selected from halogen at each occurrence; R1 is selected from -(CH2)4-; R2 is selected from methylthio.

3. The method for preparing the hole transport material as described in claim 2, characterized in that, The molar ratio of the phenoxazine compound and the dihalogenated hydrocarbon is 1:(140-160).

4. The method for preparing the hole transport material as described in claim 2, characterized in that, The first substitution reaction is carried out under basic conditions.

5. The method for preparing the hole transport material as described in claim 2, characterized in that, The catalyst for the first substitution reaction includes tetrabutylammonium bromide.

6. The method for preparing the hole transport material as described in claim 2, characterized in that, The temperature for the first substitution reaction is 60-80°C, and the time is 6-18h.

7. The method of producing a hole transporting material according to any one of claims 2 to 6, wherein One of the following conditions is met: (1) the molar ratio of the first intermediate and the triethyl phosphite is 1:(140-160); (2) the esterification reaction is carried out under protection of an inert gas; (3) the temperature for the esterification reaction is 130-150°C, and the time is 8-16h.

8. The method for producing a hole transporting material according to any one of claims 2 to 6, wherein One of the following conditions is met: (1) the molar ratio of the second intermediate and the diphenylamine compound is 1:(2-3); (2) the second substitution reaction is carried out under basic conditions and protection of an inert gas; (3) the catalyst for the second substitution reaction includes palladium acetate and tri-tert-butyl phosphine; (4) the temperature for the second substitution reaction is 80-90°C, and the time is 6-12h.

9. The method of producing a hole transporting material according to any one of claims 2 to 6, wherein One of the following conditions is met: (1) the catalyst for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group includes trimethylsilyl bromide; (2) the temperature for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group is 10-40°C, and the time is 10-30h; (3) the quenching reagent for hydrolyzing the diethyl phosphonate group on the third intermediate to form a phosphonic acid group includes methanol.

10. A perovskite solar cell, characterized by, comprising a conductive substrate, a first carrier transport layer, a perovskite layer, a second carrier transport layer and a metal electrode arranged in sequence; The first carrier transport layer or the second carrier transport layer is a hole transport layer, and the raw material of the hole transport layer comprises the hole transport material according to claim 1, or the raw material of the hole transport layer is prepared by the preparation method of the hole transport material according to any one of claims 2-9.

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