Self-assembled hole transport material and preparation method and application thereof

Abstract

The invention discloses a self-assembled hole transport material and a preparation method and application thereof. The chemical structural formula of the self-assembled hole transport material is shown as a formula A, a formula B or a formula C: # imgabs0 #, n is an integer, and n is greater than or equal to 2 and less than or equal to 6. The self-assembled hole transport material provided by the invention is low in cost and excellent in photoelectric conversion efficiency after being applied to a perovskite solar cell.

Description

Technical Field

[0001] The invention relates to the field of photoelectric conversion, and in particular to a self-assembled hole transport material and a preparation method and application thereof. Background Art

[0002] Self-assembled hole transport materials (SAMs) with anchoring groups (acetate, borate, thiol, phosphonate, etc.) have attracted much attention and are widely used in single-cell organic solar cells (OSCs), perovskite solar cells (PSCs) and stacked devices. They can spontaneously and orderly anchor on the surface of indium tin oxide (ITO) substrates through dehydration condensation between the anchoring groups and the hydroxyl groups on the surface of the ITO substrate, changing the work function of ITO while enhancing the transport of interfacial charges, thereby improving device efficiency. The functional core conjugated units of SAMs are conjugated aromatic groups that can promote intermolecular interactions to achieve firm stacking, thereby improving the transport of charge carriers. However, the solubility of these SAMs is currently poor, which increases the difficulty of solution processing, resulting in high cost and low photoelectric conversion efficiency of the resulting SAM-based devices. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a self-assembled hole transport material and a preparation method and application thereof, so as to solve the problem of low photoelectric conversion efficiency caused by the poor solubility of SAM.

[0004] To achieve the above object, the present invention provides a self-assembled hole transport material, the chemical structure of the self-assembled hole transport material is shown in Formula A, Formula B or Formula C:

[0005] Wherein, n is an integer, 2≤n≤6.

[0006] In order to achieve the above object, the present invention also provides a method for preparing the above self-assembled hole transport material, comprising the following steps: S1: mixing compound a, 1,2-dibromobutane, tetrabutylammonium bromide and KOH aqueous solution, and then heating, extracting, drying and purifying to obtain compound B;

[0007] S2: Compound b and triethyl phosphite are mixed, and the mixture is refluxed and purified under an inert atmosphere to obtain compound C;

[0008] S3: Compound c, 1,4-dioxane, trimethylsilyl bromide, methanol and distilled water are mixed and reacted until the solution becomes opaque, and then stirred, filtered, washed with water and dried to obtain compound d, wherein compound d is a self-assembled hole transport material;

[0009] Wherein, the structural formulas of compound a, compound b, compound c and compound d are respectively:

[0010]

[0011] Optionally, in step S1, the mass ratio of compound a, 1,2-dibromobutane and tetrabutylammonium bromide is (1-1.5):(15-17):(0.2-0.3).

[0012] Optionally, in step S2, the mass ratio of compound b to triethyl phosphite is (1-1.5):(83-88).

[0013] Optionally, in step S3, the mass ratio of compound c, 1,4-dioxane and trimethylsilyl bromide is (1-1.5):(14-16):(3-5).

[0014] Optionally, in step S1, the heating temperature is 65°C to 75°C; in step S2, the heating reflux temperature is 155°C to 165°C, and the reflux reaction time is ≥16 hours; in step S2, the reflux reaction time is ≥24 hours.

[0015] Optionally, the methanol is added during the mixing reaction in two additions. After the first addition of methanol, stirring is continued for ≥ 3 hours, then rotary evaporation is performed, and then the remaining amount of methanol is added for the second time.

[0016] To achieve the above objectives, the present invention also proposes an application of the above self-assembled hole transport material, wherein the self-assembled hole transport material is the above hole transport material, or is a hole transport material prepared by the above preparation method of the self-assembled hole transport material, and the self-assembled hole transport material is applied to a hole transport layer.

[0017] Optionally, the hole transport layer comprises a hole transport layer of a perovskite solar cell, and the perovskite solar cell is a pin-type perovskite solar cell.

[0018] Optionally, the preparation of the perovskite solar cell comprises the following steps: S1: pre-treating conductive glass; S2: dripping an anhydrous ethanol solution of a hole transport material with a pipette, spin coating, and thermal annealing to remove the anhydrous ethanol to obtain a hole transport layer of the perovskite solar cell; S3: preparing a component composed of Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3, transfer the perovskite precursor solution to the hole transport layer, then add chlorobenzene and anneal to obtain a perovskite light absorbing layer; S4: set an electron transport layer on the perovskite light absorbing layer; S5: set an electrode on the electron transport layer.

[0019] Optionally, in the preparation of the perovskite solar cell, the concentration of the hole transport material in the anhydrous ethanol solution of the hole transport material is 0.3 mg·mL -1 ~3 mg·mL -1 ; and / or, the concentration of the perovskite precursor solution is 1.5 mol·L -1 ~2mol·L -1 .

[0020] Beneficial effects of the present invention: The self-assembled hole transport material provided by the present invention uses 1H-phenanthro[1,10,9,8-cdefg]carbazole as the parent core unit, and utilizes the larger conjugated plane of the unit and its excellent electron-donating ability to be applied to the self-assembled molecular design, and regulates the molecular dipole moment, molecular stacking and energy level through molecular design such as carbon chain extension and introduction of functional groups. At the same time, the large π bond of the conjugated delocalization of nitrogen atoms and multiple benzene rings in the self-assembled hole transport material molecule can be used as a Lewis base to passivate the uncoordinated lead iodide ions in the perovskite phase, and the functional group of phosphonic acid with strong electron-withdrawing ability can improve the interface contact between the perovskite and the hole transport layer while regulating the molecular energy level. The amphiphilicity of the molecule is also conducive to the deposition of the perovskite, and finally it is used as a hole transport material in a pin-type perovskite solar cell, and an excellent photoelectric conversion efficiency is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is the current density-voltage curve of the self-assembled hole transport material applied to the perovskite solar cell according to the embodiment of the present invention.

[0023] 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

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0025] Unless defined otherwise, all technical and scientific terms used herein have the common meaning in the art to which the claimed subject matter belongs.

[0026] Self-assembled hole transport materials (SAMs) with anchoring groups (acetate, borate, thiol, phosphonate, etc.) have attracted much attention and are widely used in single-cell organic solar cells (OSCs), perovskite solar cells (PSCs) and stacked devices. They can spontaneously and orderly anchor on the surface of indium tin oxide (ITO) substrates through dehydration condensation between the anchoring groups and the hydroxyl groups on the surface of the ITO substrate, changing the work function of ITO while enhancing the transport of interfacial charges, thereby improving device efficiency. The functional head group of SAM is a conjugated aromatic group that can achieve firm stacking, thereby improving the transport of charge carriers. However, the solubility of these SAMs is currently poor, which increases the difficulty of solution processing, resulting in high cost and low photoelectric conversion efficiency of the resulting SAM-based devices.

[0027] In order to solve the above problems, the present invention proposes a self-assembled hole transport material, the chemical structure of the self-assembled hole transport material is shown in Formula A, Formula B or Formula C:

[0028] Wherein, n is an integer, 2≤n≤6.

[0029] The self-assembled hole transport material of this scheme uses 1H-phenanthro[1,10,9,8-cdefg]carbazole as the parent core unit. In the multiple benzene ring system, the benzene rings are coplanar, and the π electron clouds between adjacent benzene rings overlap to form an overall conjugated system. This conjugation makes the π electrons more delocalized in the entire system, increasing the stability of the system and the electron mobility.

[0030] The carbon chain will increase the steric hindrance, affecting the stacking and arrangement of the molecules, and the length of the carbon chain will affect the electron cloud distribution and conjugation degree of the molecule, thereby changing the electronic properties of the molecule. In some embodiments, the value of n is 4-6.

[0031] The large π-bond of the nitrogen atom and multiple benzene rings in the self-assembled hole transport material molecules can act as a Lewis base to passivate the uncoordinated lead iodide ions in the perovskite phase. The phosphonic acid functional group with strong electron-withdrawing ability can not only adjust the molecular energy level but also improve the interfacial contact between the perovskite and the hole transport layer. The amphiphilicity of the molecule is also conducive to the deposition of perovskite. Finally, it is used as a hole transport material in PIN-type perovskite solar cells, and a good photoelectric conversion efficiency is obtained.

[0032] In order to solve the above problems, the present invention also provides a method for preparing the above self-assembled hole transport material, comprising the following steps:

[0033] S1: Compound a, 1,2-dibromobutane, tetrabutylammonium bromide and KOH aqueous solution are mixed, and then heated, extracted, dried and purified to obtain compound B;

[0034] In some embodiments, the drying method is spin drying, and the purification method is purification using silica gel column chromatography.

[0035] S2: Compound b and triethyl phosphite are mixed, and the mixture is refluxed and purified under an inert atmosphere to obtain compound C;

[0036] In some embodiments, the heating and reflux is heating and reflux in an iron sand bath, which has good thermal conductivity and can evenly transfer heat, so that the reaction mixture is heated evenly. In some embodiments, the purification is recrystallization purification, including: introducing petroleum ether, filtering after crystallization at low temperature, and washing again with petroleum ether.

[0037] S3: Compound c, 1,4-dioxane, trimethylsilyl bromide, methanol and distilled water are mixed and reacted until the solution becomes opaque, and then stirred, filtered, washed with water and dried to obtain compound d, wherein compound d is a self-assembled hole transport material;

[0038] In this scheme, compound c, 1,4-dioxane, trimethylsilyl bromide, methanol and distilled water are sequentially added to a reaction container for mixed reaction, wherein trimethylsilyl bromide and distilled water are added dropwise, which is beneficial for controlling the reaction rate and preventing side reactions.

[0039] Wherein, the structural formulas of compound a, compound b, compound c and compound d are respectively:

[0040]

[0041] In this scheme, the above reaction process is:

[0042]

[0043] Further, in step S1, the mass ratio of compound a, 1,2-dibromobutane and tetrabutylammonium bromide is (1-1.5): (15-17): (0.2-0.3). In some embodiments, the mass ratio of compound a, 1,2-dibromobutane and tetrabutylammonium bromide is any value of (1-1.5): (15-17): (0.2-0.3) such as 1:15:0.2, 1:17:0.3, 1.5:17:0.2, etc. In some embodiments, the ratio of compound a, 1,2-dibromobutane and tetrabutylammonium bromide is (3.5-4.5) mmol: (9.5-10) mL: (0.5-1) mmol.

[0044] Further, in step S2, the mass ratio of compound b to triethyl phosphite is (1-1.5): (83-88). In some embodiments, the mass ratio of compound b to triethyl phosphite is any value of (1-1.5): (83-88) such as 1:83, 1:85, 1:88, 1.5:85, 1.5:88, etc. In some embodiments, the ratio of compound b to triethyl phosphite is (3-3.5) mmol: (10-11) mL.

[0045] Further, in step S3, the mass ratio of compound c, 1,4-dioxane and trimethylsilyl bromide is (1-1.5): (14-16): (3-5). In some embodiments, the mass ratio of compound c, 1,4-dioxane and trimethylsilyl bromide is any value of 1:14:3, 1:15:4, 1.5:15:4, 1.5:16:5, etc. (1-1.5): (14-16): (3-5). In some embodiments, the ratio of compound c, 1,4-dioxane, trimethylsilyl bromide, methanol and distilled water is (2-2.5) mmol: (12-16) mL: (21~25)mmol: (8~15)mL: (15~20)mL.

[0046] Furthermore, in step S1, the heating temperature is 65°C to 75°C; in step S2, the heating reflux temperature is 155°C to 165°C, and the reflux reaction time is ≥16 hours; in step S2, the reflux reaction time is ≥24 hours.

[0047] In some embodiments, after compound a, 1,2-dibromobutane, tetrabutylammonium bromide and KOH aqueous solution are mixed, the temperature of heating is any value between 65°C and 75°C, such as 65°C, 67°C, 69°C, 71°C, 73°C, 75°C, etc. In some embodiments, the temperature of heating and reflux in the iron sand bath is any value between 155°C and 165°C, such as 155°C, 157°C, 159°C, 161°C, 163°C, 165°C, etc.

[0048] If the reflux time is insufficient, the final target product may have a lower content; if the time is too long, the desired product may over-react or decompose.

[0049] Furthermore, the methanol is added in two times during the mixing reaction. After the first addition of methanol, stirring is continued for ≥ 3 hours, then rotary evaporation is performed, and then the remaining amount of methanol is added for the second time.

[0050] In this scheme, adding methanol in batches can control the reaction rate to initiate the reaction more slowly, which helps the reaction system to gradually adapt and carry out reaction conversion, making the reaction process smoother. Such step-by-step operation can more finely control the reaction process, improve the selectivity and efficiency of the reaction, and reduce the occurrence of adverse side reactions.

[0051] To solve the above problems, the present invention also proposes an application of the above self-assembled hole transport material, wherein the self-assembled hole transport material is the above hole transport material, or is a hole transport material prepared by the above preparation method of the self-assembled hole transport material, and the self-assembled hole transport material is applied to a hole transport layer.

[0052] Furthermore, the hole transport layer comprises a hole transport layer of a perovskite solar cell, and the perovskite solar cell is a pin-type perovskite solar cell.

[0053] For NIP-type perovskite solar cells, the hole transport layer needs to meet different energy level position requirements and needs to adapt to the different energy level arrangements with the electron transport layer and the perovskite layer to ensure effective separation and transport of charges, especially to coordinate with the adjacent electron transport layer in chemical properties to avoid adverse interactions.

[0054] Different from NIP-type perovskite solar cells, for PIN-type perovskite solar cells, the hole transport layer needs to meet a higher hole mobility to quickly transport holes and reduce recombination losses; better energy level matching, and the energy levels of the perovskite layer and the electrode must be well matched to promote the effective extraction and transmission of holes; better stability: the chemical properties can be kept stable during the preparation and operation of the perovskite layer.

[0055] The self-assembled hole transport material of this scheme is suitable for pin-type perovskite solar cells.

[0056] Furthermore, the preparation of the perovskite solar cell comprises the following steps:

[0057] S1: pre-treated conductive glass;

[0058] The ITO conductive glass was ultrasonically cleaned with deionized water containing detergent, and then ultrasonically cleaned in deionized water, acetone, and isopropanol in sequence, and the cleaned ITO conductive glass substrate was dried with a hot air gun and placed in a UV ozone treatment machine for ozone treatment. In some embodiments, the ultrasonic treatment and ozone treatment time were 20 minutes respectively.

[0059] S2: using a pipette to drop an anhydrous ethanol solution of a hole transport material, and removing the anhydrous ethanol by spin coating and thermal annealing to obtain a hole transport layer of a perovskite solar cell;

[0060] The molecule was dissolved in an ethanol solution and shaken to fully dissolve it. 50 μL of anhydrous ethanol solution that evenly dissolved the self-assembled hole transport material was added with a pipette, and then the spin coating process was started at a speed of 3000 rpm for 30 seconds. After the spin coating was completed, it was placed on a hot stage at 100°C for 30 minutes of thermal annealing to remove chlorobenzene, and a hole transport layer was obtained.

[0061] S3: Preparation component composition is Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3, transfer the perovskite precursor solution to the hole transport layer, spin-coat it, drop chlorobenzene, and then anneal to obtain a perovskite light absorbing layer;

[0062] The spin coating step includes spin coating at 1000 rpm for 10 seconds, then spin coating at 5000 rpm for 30 seconds, and dropping 100 μL of chlorobenzene within 20 seconds to 25 seconds after the second program is started, and then annealing the sample on a 150° C. hot stage for 10 minutes to form a perovskite light absorbing layer.

[0063] S4: Arranging an electron transport layer on the perovskite light absorbing layer;

[0064] In some embodiments, the electron transport layer is a C60 layer.

[0065] S5: Arranging an electrode on the electron transport layer.

[0066] In some embodiments, the electrode material is Au or Ag.

[0067] Furthermore, in the preparation of the perovskite solar cell, the concentration of the hole transport material in the anhydrous ethanol solution of the hole transport material is 0.3 mg·mL -1 ~3 mg·mL -1 ; The concentration of the perovskite precursor solution is 1.5 mol·L -1 ~2mol·L -1 .

[0068] In some embodiments, the concentration of the hole transport material is 0.5 mg·mL -1 , 1mg·mL -1 , 1.5mg·mL -1 , 2mg·mL -1 , 2.5mg·mL -1 , 3mg·mL -1 Equivalent to 0.3 mg mL -1 ~3 mg·mL -1 Any value in .

[0069] Embodiment 1:

[0070] In a 100mL reaction tube, add the raw material compound 1 (1.074g, 4.05mmol), 1,2-dibromobutane 9.7mL, tetrabutylammonium bromide (260.2mg, 0.81mmol) and 2.2mL of 50% KOH aqueous solution in sequence. Then heat to 70°C and react overnight. After the spot plate reaction is complete, cool the reaction mixture to room temperature, wash with water, and extract with dichloromethane. Dry with anhydrous magnesium sulfate, spin dry, and purify with silica gel column chromatography (petroleum ether / dichloromethane, v / v, 3:1) to obtain compound B;

[0071] Add reactant B (1.208 g, 3.02 mmol) and 10.4 mL of triethyl phosphite into a 100 mL reaction tube, evacuate and pass nitrogen for several times, and reflux in an iron sand bath at 160°C for 16 h. After the reaction is complete, the mixture is cooled to room temperature, and 200 mL of petroleum ether is introduced into the reaction mixture for crystallization at low temperature. The solid is filtered and then washed with petroleum ether to obtain white powder compound C;

[0072] Compound C (1.029 g, 2.25 mmol) was dissolved in anhydrous 1,4-dioxane (15 mL) under nitrogen atmosphere and trimethylsilane bromide (3.0 mL, 22.52 mmol) was added dropwise. The reaction was allowed to react at room temperature for 24 h. Afterwards, 2 mL of methanol was added and stirring continued for 3 h. Part of the solvent was removed by rotary evaporation, and then 8 mL of methanol was added. Finally, 15 mL of distilled water was added dropwise until the solution was opaque and stirred overnight. The product was filtered out, washed with water, and dried to obtain a self-assembled hole transport material (4-(1H-phenanthro[1,10,9,8-cdefg]carbazole-1-yl)butyl)phosphonic acid.

[0073]

[0074] Embodiment 2:

[0075] The preparation method is the same as that of Example 1, except that the compound 1 in the first step reaction is 3,10-dibromo-1H-phenanthro[1,10,9,8-cdefg]carbazole.

[0076] Embodiment 3:

[0077] The preparation method is the same as that of Example 1, except that the compound 1 in the first step reaction is 3,10-dimethoxy-1H-phenanthro[1,10,9,8-cdefg]carbazole.

[0078] Embodiment 4:

[0079] The preparation method is the same as that of Example 1, except that: the prepared self-assembled hole transport material n=6.

[0080] Embodiment 5:

[0081] The preparation method is the same as that of Example 1, except that: the prepared self-assembled hole transport material n=2.

[0082] Furthermore, the above-mentioned embodiment 1 is used to prepare a perovskite solar cell, and the preparation steps include:

[0083] 1. Cleaning of ITO conductive glass

[0084] The protective film of the ITO conductive glass was removed, and the glass was first ultrasonically cleaned with deionized water containing detergent, and then ultrasonically treated in deionized water, acetone, and isopropanol for 20 minutes in sequence.

[0085] 2. Preparation of hole transport layer

[0086] Use a hot air gun to dry the cleaned ITO conductive glass substrate and place it in a UV ozone treatment machine for 20 minutes. Dissolve the molecule in ethanol solution and shake it to fully dissolve it. The concentration is 0.3-3 mg·mL -1 After the ITO was taken out and cooled to room temperature, it was placed on a coater in a nitrogen atmosphere in a glove box, and 50 μL of a uniformly dissolved 4DTPC-PACz anhydrous ethanol solution was added with a pipette, and then the spin coating process was started at a speed of 3000 rpm for 30 seconds. After the spin coating was completed, it was placed on a hot stage at 100°C for 30 minutes of thermal annealing to remove chlorobenzene, and the hole transport layer was obtained.

[0087] 3. Preparation of perovskite light absorbing layer

[0088] The components of the perovskite precursor solution used in the experiment are Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3, where the concentration of the precursor solution is 1.61 mol·L -1 A mixture of 19.8 mg CsI, 16.2 mg MABr, 20.3 mg MACl, 224.4 mg FAI, and 742.2 mg PbI2 powders was dissolved in 1 mL of anhydrous DMF / DMSO mixture solvent (4 / 1, v / v), and stirred at 60°C for 2 hours to fully dissolve it.

[0089] The perovskite film was prepared by a one-step method, and the anti-solvent was chlorobenzene. 50 μL of the perovskite precursor solution was transferred to the hole transport layer and the spin coating procedure was 1000 rpm for 10 s and 5000 rpm for 30 s. 100 μL of chlorobenzene was added dropwise within 20 to 25 s after the second procedure was started, and the sample was then annealed on a 150°C hot plate for 10 minutes to form a perovskite light absorbing layer.

[0090] 4. Preparation of functional layer and metal electrode layer

[0091] The treated substrate was placed in a metal vacuum evaporation chamber in a glove box, and then 35nm thick C60, 7nm thick BCP and 100nm Ag electrode were successively evaporated at a high vacuum degree, finally obtaining a complete area of ​​0.06cm 2 PSCs devices.

[0092] The device performance of perovskite solar cells was tested under standard sunlight (AM 1.5G).

[0093] The test results are shown in the appendix of the manual. Figure 1 From the figure, it can be seen that the open circuit voltage Voc of the reverse scanning device of the perovskite solar cell using 4DTPC-PACz as the hole transport material is 1.152V, and the short circuit current is 23.15mA / cm -2 , the filling factor is 82.75%, and the photoelectric conversion efficiency is 22.61%. The results show that 4DTPC has great application potential as a core conjugated unit in hole transport materials in inverted perovskite solar cell devices.

[0094] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A self-assembled hole transport material, characterized in that: The chemical structural formula of the self-assembled hole transport material is shown in Formula A, Formula B or Formula C: Wherein, n is an integer, 2≤n≤6.

2. A method for preparing a self-assembled hole transport material, characterized in that: The following steps are involved: S1: Compound a, 1,2-dibromobutane, tetrabutylammonium bromide and KOH aqueous solution are mixed, and then heated, extracted, dried and purified to obtain compound B; S2: Compound b and triethyl phosphite are mixed, and the mixture is refluxed and purified under an inert atmosphere to obtain compound C; S3: Compound c, 1,4-dioxane, trimethylsilyl bromide, methanol and distilled water are mixed and reacted until the solution becomes opaque, and then stirred, filtered, washed with water and dried to obtain compound d, wherein compound d is a self-assembled hole transport material; Wherein, the structural formulas of compound a, compound b, compound c and compound d are respectively:

3. The method for preparing the self-assembled hole transport material according to claim 2, characterized in that: In step S1, the mass ratio of compound a, 1,2-dibromobutane and tetrabutylammonium bromide is (1-1.5):(15-17):(0.2-0.3).

4. The method for preparing the self-assembled hole transport material according to claim 2, characterized in that: In step S2, the mass ratio of compound b to triethyl phosphite is (1-1.5):(83-88).

5. The method for preparing the self-assembled hole transport material according to claim 2, characterized in that: In step S3, the mass ratio of compound c, 1,4-dioxane and trimethylsilyl bromide is (1-1.5):(14-16):(3-5).

6. The method for preparing the self-assembled hole transport material according to claim 2, characterized in that: In step S1, the temperature of the heating is 65°C to 75°C; And / or, in step S2, the temperature of the heating reflux is 155° C. to 165° C., and the reflux reaction time is ≥ 16 hours; And / or, in step S2, the reflux reaction time is ≥ 24 hours.

7. The method for preparing the self-assembled hole transport material according to claim 2, characterized in that: The methanol is added in two times during the mixing reaction. After the first addition of methanol, stirring is continued for ≥ 3 hours, then rotary evaporation is performed, and then the remaining amount of methanol is added for the second time.

8. An application of a self-assembled hole transport material, characterized in that: The self-assembled hole transport material is the hole transport material as claimed in claim 1, or is a hole transport material prepared by the method for preparing a self-assembled hole transport material as claimed in any one of claims 2 to 7, and the self-assembled hole transport material is applied to a hole transport layer.

9. The use of the hole transport material according to claim 8, characterized in that: The hole transport layer comprises a hole transport layer of a perovskite solar cell, and the perovskite solar cell is a pin-type perovskite solar cell.

10. The use of the hole transport material according to claim 9, characterized in that: The preparation of the perovskite solar cell comprises the following steps: S1: pre-treated conductive glass; S2: using a pipette to drop an anhydrous ethanol solution of a hole transport material, and removing the anhydrous ethanol by spin coating and thermal annealing to obtain a hole transport layer of a perovskite solar cell; S3: Preparation component composition is Cs 0.05 FA 0.85 MA 0.1 Pb(I 0.97 Br 0.03 )3, transfer the perovskite precursor solution to the hole transport layer, spin-coat it, drop chlorobenzene, and then anneal to obtain a perovskite light absorbing layer; S4: Arranging an electron transport layer on the perovskite light absorbing layer; S5: Arranging an electrode on the electron transport layer.

11. The use of the hole transport material according to claim 10, characterized in that: In the preparation of the perovskite solar cell, the concentration of the hole transport material in the anhydrous ethanol solution of the hole transport material is 0.3 mg·mL -1 ~3 mg·mL -1 ; And / or, the concentration of the perovskite precursor solution is 1.5 mol·L -1 ~2mol·L -1 .

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