Hole transport layer, perovskite solar cell and preparation method

Abstract

The invention belongs to the photovoltaic field, and particularly relates to a hole transport layer, a perovskite solar cell and a preparation method. The hole transport layer provided by the invention comprises self-assembled monolayer molecules and a compound with ultraviolet absorption as shown in the formula I. The ultraviolet stability of the hole transport layer can be improved by introducing the compound in the formula I into the hole transport layer, and meanwhile, the performance of a device can be improved through the passivation effect of carbonyl and hydroxyl on the compound in the formula I in cooperation with the ultraviolet stability effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of photovoltaics, and particularly relates to a hole transport layer, a perovskite solar cell and a preparation method. BACKGROUND

[0002] Thanks to the development of perovskite film formation technology and its own material technology, the photoelectric conversion efficiency of perovskite solar cell (PSC) technology has been improved from 3.8% to more than 26% in the past decade. Therefore, developing high-efficiency, stable and low-cost charge transport materials, especially hole transport materials (HTM), is crucial to promote the commercialization of PSC.

[0003] Recently, an anchoring self-assembly strategy has been proved to be able to construct an efficient hole transport layer for high-performance p-i-n structure PSC. This process uses self-assembled molecules as HTM, which include anchoring groups (such as carboxyl groups) that can spontaneously adsorb onto the surface of the oxide substrate to form a monolayer coverage, i.e. self-assembled monolayers (SAMs). Compared with the traditional thick hole transport layer (HTL) based on spin coating or spray pyrolysis, SAMs have the advantages of minimum material consumption and low parasitic absorption. In addition, the method based on chemical bath deposition is a low-cost and scalable process route, which has been successfully applied to small modules and large-area perovskite silicon tandem solar cells.

[0004] However, the problem of ultraviolet stability of SAMs materials and the problem of long-term operation stability have gradually attracted the attention of researchers. Therefore, how to avoid the damage of ultraviolet light to SAMs materials and prepare a hole transport layer with ultraviolet stability is of great significance to the industrialization process of perovskite photovoltaics. SUMMARY

[0005] To solve the problems existing in the prior art and improve the ultraviolet stability of the hole transport layer, the application introduces an ultraviolet absorber with the structure of a compound of formula I with functional groups such as carbonyl and hydroxyl into the hole transport layer, which can not only reduce the influence of ultraviolet light on hole transport molecules but also has a defect passivation effect, thereby improving the performance of perovskite solar cells.

[0006] Specifically, the application provides a hole transport layer, which comprises self-assembled monolayer molecules and a compound of formula I

[0007] In formula I, R1, R2, R3 and R4 are independently selected from hydrogen atom, hydroxyl, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl and C1-C10 alkoxy;

[0008] R1, R2, R3 and R4 are not hydrogen atoms at the same time, and at least one is a hydroxyl group.

[0009] In one or more embodiments, the compound of Formula I has an ultraviolet absorption peak at 250-400 nm.

[0010] In one or more embodiments, R1, R2, R3, and R4are each independently selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1-C10 alkyl group, and a C1-C10 alkoxy group.

[0011] In one or more embodiments, R1, R2, R3, and R4are each independently selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1-C4 alkyl group, and a C1-C8 alkoxy group.

[0012] In one or more embodiments, R2is selected from a hydroxyl group, and R1, R3, and R4are each independently selected from the group consisting of a hydrogen atom, a hydroxyl group, a C1-C4 alkyl group, and a C1-C8 alkoxy group.

[0013] In one or more embodiments, the compound of Formula I is one or more of bis(2-hydroxy-4-methoxyphenyl)methanone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 4,4'-dihydroxybenzophenone, 2,4-hydroxybenzophenone, (2-hydroxy-4-methoxyphenyl)(2-hydroxyphenyl)methanone, (2-hydroxy-4-methoxyphenyl)phenylmethanone, and 2-hydroxy-4-n-hexyloxybenzophenone.

[0014] In one or more embodiments, the compound of Formula I is 2-hydroxy-4-n-octyloxybenzophenone.

[0015] In one or more embodiments, the compound of Formula I has a mass fraction of 1-20% in the hole transport layer.

[0016] In one or more embodiments, the compound of Formula I has a mass fraction of 10-15% in the hole transport layer.

[0017] In one or more embodiments, the self-assembled monolayer molecule is one or more selected from the group consisting of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethyl-9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, [4-(9H-carbazol-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, and [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid, [2-(3,6-dichloro-9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid, [4-(3,6-diphenyl-9H-carbazol-9-yl)butyl]phosphonic acid, [2-(9H-9'-phenyl-3,3'-bicarbazol-9-yl)butyl]phosphonic acid, [2-(3,3'-bicarbazol-9-yl)butyl]bisphosphonic acid, [4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)phenyl]phosphonic acid, [2-(7H-dibenzo-carbazol-7-yl)ethyl]phosphonic acid, [4-(7H-dibenzo-carbazol-7-yl)butyl]phosphonic acid, [4-(2,7-dibromo-9,9-dimethylacridin-10(9H)-yl)butyl]phosphonic acid, [4-(3,7-dibromo-10H-phenothiazin-10-ylbutyl]phosphonic acid, and (2-(pyren-1-yl)ethyl)phosphonic acid.

[0018] In one or more embodiments, the mass fraction of the self-assembled monolayer molecule in the hole transport layer is 80% to 99%.

[0019] In one or more embodiments, the mass fraction of the self-assembled monolayer molecule in the hole transport layer is 85% to 90%.

[0020] In one or more embodiments, the thickness of the hole transport layer is 1 to 5 nm.

[0021] In another aspect, the present application provides a method for preparing the hole transport layer of any one of the embodiments of the present application, the method comprising dispersing the self-assembled monolayer molecule and the compound of Formula I in a solvent, stirring to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution, and annealing to obtain the hole transport layer.

[0022] In one or more embodiments, the mass of the self-assembled monolayer molecule in the hole transport layer precursor solution is 0.5 to 1.0 mg per milliliter of solvent.

[0023] In one or more embodiments, the mass of the compound of Formula I is 0.01-0.20 mg per milliliter of solvent in the hole transport layer precursor solution.

[0024] In one or more embodiments, the solvent comprises a first solvent selected from one or both of ethanol and isopropanol, and an optional second solvent selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran.

[0025] In one or more embodiments, the coating is one or more selected from spin coating, doctor blading, spray coating, spray pyrolysis, and slot coating.

[0026] In one or more embodiments, the annealing is at a temperature of 90-120 °C.

[0027] In one or more embodiments, the annealing is for a time of 5-60 min.

[0028] In another aspect, the present application provides a hole transport layer prepared using the method described in any one of the embodiments of the present application.

[0029] In another aspect, the present application provides a perovskite solar cell comprising the hole transport layer described in any one of the embodiments of the present application.

[0030] The present application adds an appropriate amount of benzophenone ultraviolet absorber having the structure of the compound of Formula I into the hole transport layer. By introducing the ultraviolet absorber in a mass fraction of 1-20% into the hole transport layer, on the one hand, the ultraviolet light can be effectively absorbed, avoiding the bond cleavage of the hole transport material, especially SAMs material, under ultraviolet light irradiation; on the other hand, the ultraviolet absorber contains defect passivation groups such as carbonyl and hydroxyl groups, which can effectively passivate the perovskite bottom interface; through the defect passivation effect and the ultraviolet stabilization effect, the performance and stability of the perovskite solar cell can be synergistically improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Structure diagram of the trans-wide band gap perovskite solar cell in some embodiments. DETAILED DESCRIPTION

[0032] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings understood by those skilled in the art of the present application, and in case of conflict, the definitions in the specification shall prevail.

[0033] Theories and mechanisms described and disclosed herein, whether correct or not, should not be considered limiting of the scope of the present application, which is defined only by the claims. The present application can be implemented in a variety of ways, including means both large and small, and ought not to be limited to the implementations described herein, but should be construed and implemented broadly.

[0034] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," and the like are intended to be open-ended and allow for the inclusion of not only the recited feature or element but also other features or elements known in the art or later developed. Thus, as used herein, the term "comprises" is inclusive of the recited features or elements, but also includes other features or elements not recited.

[0035] As used herein, all features, such as numerical values, amounts, contents and concentrations, which are defined in the form of numerical ranges or percentage ranges, are intended to be merely for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0036] As used herein, unless otherwise specified, percentages are by mass percentage, and ratios are by mass ratio.

[0037] As used herein, when describing embodiments or examples, it is understood that the invention is not limited to these embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein, which are within the scope of the claims, are intended to be encompassed by the claims.

[0038] As used herein, in order to make the description concise, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of the technical features, the technical features in each embodiment or example can be combined in any manner, and all possible combinations should be considered as the scope described in the specification.

[0039] The present application provides a hole transport layer comprising self-assembled monolayer molecules and a compound of formula I as an ultraviolet absorber ;

[0040] In formula I, R1, R2, R3 and R4 are each independently selected from a hydrogen atom, a hydroxyl group, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group and a C1-C10 alkoxy group;

[0041] R1, R2, R3 and R4 are not simultaneously a hydrogen atom.

[0042] The compound of formula I suitable for the present application has an ultraviolet absorption peak at 250-400 nm. Controlling the wavelength of the ultraviolet absorber in the above range is advantageous for better improving the ultraviolet stability of the SAMs material, thereby improving the performance of the perovskite solar cell.

[0043] In some embodiments, R3 and R4 are hydrogen atoms, R2 is a hydrogen atom or a hydroxyl group, and R1 is a hydrogen atom, a C1-C4 linear alkyl group (e.g., methyl, ethyl, n-propyl, n-butyl, or the like), or a C1-C8 linear alkoxy group (e.g., methoxy, ethoxy, n-propyloxy, n-butyloxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, or the like). Controlling the substituents R1 and R2 of the compound of Formula I within the above ranges is advantageous for regulating the UV absorption peak of the compound of Formula I, improving the UV stability of the hole transport layer, and simultaneously passivating the perovskite interface, and improving the performance of the perovskite solar cell through the synergistic effect of passivation and UV resistance.

[0044] In some embodiments, R2 and R3 are hydrogen atoms or a hydroxyl group, and R1 and R4 are independently selected from a hydrogen atom, a C1-C4 linear alkyl group (e.g., methyl, ethyl, n-propyl, n-butyl, or the like), or a C1-C8 linear alkoxy group (e.g., methoxy, ethoxy, n-propyloxy, n-butyloxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, or the like). Controlling the substituents R1 and R2 of the compound of Formula I within the above ranges is advantageous for regulating the UV absorption peak of the compound of Formula I, improving the UV stability of the hole transport layer, and simultaneously passivating the perovskite interface, and improving the performance of the perovskite solar cell through the synergistic effect of passivation and UV resistance.

[0045] The mass fraction of the compound of Formula I in the hole transport layer is 1% to 20%, such as 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, and preferably 10% to 15%. Controlling the mass fraction of the compound of Formula I within the above ranges helps to avoid the adverse effects of the additive on the transport performance of the hole transport layer, and better guarantees the UV stability thereof.

[0046] In some embodiments, the mass fraction of the self-assembled monolayer molecule in the hole transport layer is 80% to 99%, such as 82%, 84%, 86%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and preferably 85% to 90%.

[0047] The thickness of the hole transport layer of the present application is 1 to 5 nm, such as 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm.

[0048] In the present application, the perovskite structure material can be AX and BX2, the A ion is a monovalent cation, which can include but is not limited to cesium ion (Cs + ), rubidium ion (Rb + ), methylamine ion (CH3NH3 + , MA + ), and formamidinium ion (CH(NH2)2+ , FA + ) one or more of the group consisting of Pb 2+ ) and / or Sn 2+ ); X ion is a monovalent anion, which can include but is not limited to one or more of the group consisting of I - ), Br - ) and Cl - ); preferably, in the perovskite structure material, A ion is selected from one or more of the group consisting of Cs ion, methylamine ion and formamidine ion; B ion is Pb ion; X ion is I ion and / or Br ion. In some embodiments, the perovskite structure material is PbI2and CH3NH3I.

[0049] The electron transport layer of the present application can be one or more selected from n-type monocrystalline silicon, n-type polycrystalline silicon, n-type amorphous silicon, TiO2, SnO2, ZnO, ZrO2, GZO, IZO, FTO, ITO, BaSnO3, TiSnO x , SnZnO x , fullerene (e.g. C60and C70) and fullerene derivative (e.g. PCBM).

[0050] The electrode material of the present application can be one or more selected from Au, Ag, Al, Cu, graphene, TCO material and nanocrystalline silicon, and the electrode preparation method includes but is not limited to one or more of spin coating, blade coating, evaporation, printing, spraying, spray pyrolysis and slot coating.

[0051] The present application provides a method for preparing a hole transport layer, which comprises dispersing a self-assembled monolayer molecule and a compound of formula I in a solvent, stirring uniformly to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution, and then annealing to obtain a hole transport layer.

[0052] In the hole transport layer precursor solution, the mass of the self-assembled monolayer molecule is 0.5-1.0 mg per milliliter of solvent, for example 0.55 mg, 0.6 mg, 0.65 mg, 0.7 mg, 0.75 mg, 0.8 mg, 0.85 mg, 0.9 mg, 0.95 mg.

[0053] The mass of the compound of Formula I in the hole transport layer precursor solution is 0.01-0.20 mg per milliliter of solvent, for example, 0.02 mg, 0.03 mg, 0.04 mg, 0.05 mg, 0.06 mg, 0.07 mg, 0.08 mg, 0.09 mg, 0.10 mg, 0.11 mg, 0.12 mg, 0.13 mg, 0.14 mg, 0.15 mg, 0.16 mg, 0.17 mg, 0.18 mg, 0.19 mg.

[0054] In the present application, the coating method can be one or more of spin coating, blade coating, spray coating, spray pyrolysis and slot coating.

[0055] In the present application, the annealing process is one-step annealing or two-step annealing. The annealing temperature can be 90-120℃, for example, 95℃, 100℃, 105℃, 110℃, 115℃. In the present application, the annealing time can be 5-60 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min.

[0056] The present application provides a perovskite solar cell comprising the hole transport layer of the present application. In the present application, the perovskite solar cell can include a single-junction perovskite solar cell or a tandem perovskite solar cell; the perovskite solar cell in the present application is usually a reverse perovskite solar cell (p-i-n type perovskite solar cell). Specifically, the perovskite solar cell can be a reverse single-junction perovskite solar cell, a tandem perovskite solar cell.

[0057] In the present application, the reverse single-junction perovskite solar cell can sequentially include a transparent conductive substrate, a hole transport layer, a perovskite thin film, an electron transport layer, a hole blocking layer and a metal electrode. In the present application, the tandem perovskite solar cell can sequentially include a bottom electrode, a bottom cell, a tunneling layer, a perovskite top cell and a top electrode, and the top cell can sequentially include a hole transport layer, a perovskite thin film and an electron transport layer.

[0058] The present application will be described in detail below by way of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present application. The methods, reagents and materials used in the examples are conventional in the art unless otherwise specified. The raw material compounds in the examples can be purchased through commercial channels.

[0059] In the present application, the ultraviolet absorbers in the examples are purchased from Sigma-Aldrich Company.

[0060] Example 1

[0061] This example prepares a structure as shown inFigure 1 The trans-wide band gap perovskite solar cell is shown, and the specific steps are as follows:

[0062] (1) Preparation of the bottom cell:

[0063] The indium tin oxide conductive glass (ITO conductive glass) was sequentially cleaned with deionized water, acetone and isopropanol for 15 min each by ultrasonic cleaning, and finally placed in a drying oven at 75°C for drying; the dried ITO conductive glass substrate was placed in a UV-ozone machine for 25 min to remove organic impurities on the surface and optimize the surface wettability;

[0064] (2) 0.9 mg of self-assembled monolayer material (4-(3,6-diphenyl-9H-carbazole-9-yl) butyl phosphate, Ph-4PACz) and 0.1 mg of ultraviolet absorber 2-hydroxy-4-n-octyloxybenzophenone (UV-531, ultraviolet absorption peak maximum 290 nm, absorption range 265-380 nm) were dispersed in 1 mL of ethanol and 50 μL of N,N-dimethylformamide (DMF) mixed solution; ultrasonic for 20 min to obtain a hole transport material precursor solution; 30 μL of the above hole transport material precursor solution was added to the surface of the ITO conductive glass, and then spin-coated on the ITO conductive glass at a speed of 5000 rpm for 30 s, then the above ITO conductive glass was placed on a hot stage at 100°C for 10 min of annealing, to obtain a hole transport layer with a thickness of 3 nm;

[0065] (3) 722.08 mg of lead iodide and 238.50 mg of iodomethylamine were dissolved in 1 mL of DMF, and stirred at room temperature until completely dissolved to obtain a perovskite precursor solution; in a nitrogen glove box, 30 μL of the perovskite precursor solution was coated on the surface of the hole transport layer, then spin-coated at a speed of 1000 rpm for 10 s, then spin-coated at a speed of 5000 rpm for 30 s, and at the same time, 125 μL of chlorobenzene was quickly added when spin-coated at a speed of 5000 rpm for 25 s, then it was placed on a hot stage and annealed at 100°C for 40 min to obtain a perovskite light absorbing layer with a thickness of 500 nm;

[0066] (5) 20 mg of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was dissolved in 1 mL of chlorobenzene, and stirred at room temperature to obtain a PCBM solution; 30 μL of the PCBM solution was coated on the surface of the perovskite light absorbing layer, then spin-coated at a speed of 3000 rpm for 60 s to form an electron transport layer with a thickness of 30 nm;

[0067] (6) 0.5 mg of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was dissolved in 1 mL of isopropanol, and stirred at room temperature to obtain a hole blocking layer solution; 40 μL of the hole blocking layer solution was added dropwise to the surface of the electron transport layer, and then spin-coated at 5000 rpm for 35 s to obtain a hole blocking layer with a thickness of 6 nm;

[0068] (7) The ITO conductive glass on which the hole blocking layer, the electron transport layer, the perovskite light absorbing layer and the hole transport layer were prepared was transferred into a vacuum coating instrument, and the vacuum degree was drawn to 3*10 -4 Pa to evaporate a silver electrode, and a silver electrode with a thickness of 100 nm was formed on the hole blocking layer to obtain an electrode layer.

[0069] Example 2

[0070] The other conditions of this example were the same as those of Example 1, except that the ultraviolet absorber used in this example was bis(2-hydroxy-4-methoxyphenyl) methanone (ultraviolet absorption peak maximum 340 nm, absorption range 260-390 nm) with the same mass.

[0071] Example 3

[0072] The other conditions of this example were the same as those of Example 1, except that the ultraviolet absorber used in this example was 2-hydroxy-4-methoxybenzophenone (ultraviolet absorption peak maximum 285 nm, absorption range 260-370 nm) with the same mass.

[0073] Example 4

[0074] The other conditions of this example were the same as those of Example 1, except that the mass of the ultraviolet absorber used in this example was 0.20 mg.

[0075] Example 5

[0076] The other conditions of this example were the same as those of Example 1, except that the mass of the ultraviolet absorber used in this example was 0.01 mg.

[0077] Comparative Example 1

[0078] The other conditions of this comparative example were the same as those of Example 1, except that the hole transport layer of this comparative example only used Ph-4PACz as the material of the hole transport layer, and no additives were added.

[0079] Comparative Example 2

[0080] The other conditions of this comparative example were the same as those of Example 1, except that the ultraviolet absorber used in this comparative example was 2-(2'-hydroxy-5'-methylphenyl) benzotriazole with the same mass.

[0081] Comparative Example 3

[0082] The other conditions of Comparative Example 3 were the same as those of Example 1, except that the mass of the UV additive in the comparative example was 0.005 mg.

[0083] Comparative Example 4

[0084] The other conditions of Comparative Example 4 were the same as those of Example 1, except that the mass of the UV additive in the comparative example was 0.5 mg.

[0085] Test Example 1

[0086] At 25°C, under AM 1.5G standard solar spectrum, light intensity of 100 mW / cm 2 Next, using a solar simulator, the voltage range was set to -0.2-1.3V, and the performance (open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency) of the solar cell modules in Examples 1-5 and Comparative Examples 1-4 was measured. UV aging was performed using a UV2000 UV aging oven from Shanghai EYEN Laboratory Equipment Co., Ltd. at 50°C for 20 kWh / m 2 UV aging, and the specific results are shown in Table 1.

[0087] (1) Open-circuit voltage (Voc): the voltage value corresponding to the current equal to zero.

[0088] (2) Short-circuit current density (Jsc): the current value when the voltage is zero is the short-circuit current (Isc), and the current size on the unit cell surface area is the short-circuit current density.

[0089] (3) Fill factor (FF): the ratio of the maximum output power (Pmax) of the cell to the product of the open-circuit voltage and the short-circuit current, the calculation formula is (Pmax / Voc*Isc), and the maximum power point is the point at which the cell output power reaches the maximum value.

[0090] (4) Photoelectric conversion efficiency (PCE): the photoelectric conversion efficiency refers to the ratio of the maximum output power to the incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0091] Table 1: Photovoltaic performance test results of the solar cell modules of Examples 1-5 and Comparative Examples 1-4

[0092]

[0093] As can be seen from Table 1, in the examples, by adding benzophenone containing benzene ring, carbonyl and hydroxyl as ultraviolet additive to the hole transport layer, the perovskite solar cell prepared still maintains more than 90% of the initial efficiency after ultraviolet light irradiation of 20 kWh, while the perovskite solar cell in Comparative Example 1 decreases to 81.7% of the initial efficiency, indicating that the introduction of ultraviolet absorber can improve the ultraviolet stability of the perovskite solar cell. At the same time, Comparative Example 2 uses a triazole ultraviolet absorber, due to its solubility limitation, resulting in poor initial performance of the device, indicating the advantage of benzophenone ultraviolet absorber in structure.

Claims

1. A hole transport layer, characterized in that, The hole transport layer comprises a self-assembled monolayer molecule and a compound of formula I. In Formula I, R1, R2, R3 and R4 are independently selected from hydrogen atom, hydroxyl group, C1-C10 alkyl group, C2-C10 alkenyl group, C2-C10 alkynyl group and C1-C10 alkoxy group, respectively; R1, R2, R3, and R4 are not all hydrogen atoms at the same time, and at least one of them is a hydroxyl group.

2. The hole transport layer as described in claim 1, characterized in that, The ultraviolet absorption peak of the compound of formula I is in the range of 250-400 nm.

3. The hole transport layer as described in claim 1, characterized in that, In Formula I, R1, R2, R3 and R4 are independently selected from hydrogen atoms, hydroxyl groups, C1-C10 alkyl groups and C1-C10 alkoxy groups, respectively; Preferably, R1, R2, R3 and R4 are each independently selected from hydrogen atoms, hydroxyl groups, C1-C4 alkyl groups and C1-C8 alkoxy groups; Preferably, R2 is a hydroxyl group, and R1, R3 and R4 are independently selected from hydrogen atoms, hydroxyl groups, C1-C4 alkyl groups and C1-C8 alkoxy groups, respectively.

4. The hole transport layer as described in claim 1, characterized in that, The compound of Formula I is one or more of bis(2-hydroxy-4-methoxyphenyl) methyl ketone, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 4,4'-dihydroxybenzophenone, 2,4-hydroxybenzophenone, (2-hydroxy-4-methoxyphenyl)(2-hydroxyphenyl) methyl ketone, (2-hydroxy-4-methoxyphenyl)phenyl methyl ketone, and 2-hydroxy-4-n-hexyloxybenzophenone, preferably one or more of 2-hydroxy-4-n-octyloxybenzophenone, bis(2-hydroxy-4-methoxyphenyl) methyl ketone, and 2-hydroxy-4-methoxyphenyl methyl ketone, more preferably 2-hydroxy-4-n-octyloxybenzophenone; and / or The mass fraction of the compound of Formula I in the hole transport layer is 1%-20%, preferably 10-15%.

5. The hole transport layer as described in claim 1, characterized in that, The self-assembled monolayer molecule is selected from [2-(9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethyl-9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid, and [4-(3,6-dimethoxy-9H-carbazole-9-yl)butyl]phosphonic acid, [2-(3,6-dichloro-9H-carbazole-9-yl)ethyl]phosphonic acid, [2-(3,6-dibromo-9H-carbazole-9-yl)ethyl]phosphonic acid, [4-(3,6-diphenyl-9H-carbazole-9-yl)butyl]phosphonic acid, […]. [2-(9H-9'-phenyl-3,3'-dibicarbazol-9-yl)butyl]phosphonic acid, [2-(3,3'-dibicarbazol-9-yl)butyl]bisphosphonic acid, [4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl]phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)phenyl]phosphonic acid, [2-(7H-dibenzocarbazol-7-yl)ethyl]phosphonic acid, [4-(7H-dibenzocarbazol-7-yl)butyl]phosphonic acid, [4-(2,7-dibromo-9,9-dimethylacridin-10(9)hydro-yl)butyl]phosphonic acid, [4-(3,7-dibromo-10H-phenthiazin-10-ylbutyl]phosphonic acid and (2-(pyrene-1-yl)ethyl)phosphonic acid; and / or one or more of these; The mass fraction of the self-assembled monolayer molecules in the hole transport layer is 80%-99%, preferably 85%-90%.

6. The hole transport layer as described in claim 1, characterized in that, The thickness of the hole transport layer is 1-5 nm.

7. A method for preparing a hole transport layer according to any one of claims 1-6, characterized in that, The method includes dispersing a self-assembled monolayer molecule and a compound of formula I in a solvent, stirring until homogeneous to obtain a hole transport layer precursor solution, coating the hole transport layer precursor solution, and then annealing to obtain a hole transport layer.

8. The method as described in claim 7, characterized in that, The method has one or more of the following characteristics: In the hole transport layer precursor solution, the mass of the self-assembled monolayer molecule is 0.5-1.0 mg per milliliter of solvent; In the hole transport layer precursor solution, the mass of the compound of formula I is 0.01-0.20 mg per milliliter of solvent; The solvent includes a first solvent and an optional second solvent, wherein the first solvent is selected from one or both of ethanol and isopropanol, and the second solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran; The coating is selected from one or more of spin coating, blade coating, spray coating, spray pyrolysis and slot coating; The annealing temperature is 90-120℃; The annealing time is 5-60 minutes.

9. A hole transport layer prepared by the method of claim 7 or 8.

10. A perovskite solar cell comprising a hole transport layer according to any one of claims 1-6 and 9.

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