Hole transport layer, perovskite solar cell, preparation method and application

Abstract

The invention belongs to the field of solar cells, and particularly relates to a hole transport layer, a perovskite solar cell, a preparation method and application. The hole transport layer sequentially comprises a NiOx layer and a self-assembly monomolecular layer from the thickness direction; the self-assembled monomolecular layer comprises a self-assembled monomolecular layer material and 1-hydroxypyrazole. The prepared perovskite solar cell is excellent in photovoltaic performance, and the preparation process is simple.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and in particular relates to a hole transport layer, a perovskite solar cell, and a preparation method and use thereof. Background Art

[0002] NiOx is an inorganic p-type semiconductor that is commonly used as a hole transport layer (HTL) for inverted and tandem perovskite solar cells (PSCs) due to its cost-effectiveness, stability, and scalability. Studies have found that oxygen vacancies and uncoordinated metal ion defects on the NiOx surface, submicron-scale defects on the lower surface of the perovskite material, and non-radiative recombination at the interface caused by the interaction between NiOx and the perovskite film can adversely affect the stability of perovskite solar cells and lead to a loss in over-cycle voltage (VOC), which poses a major obstacle to the realization of efficient and highly stable inverted PSCs.

[0003] Therefore, in order to solve the interface problem in NiOx / perovskite heterojunction, methods such as using inorganic salts, self-assembled monolayer materials (SAM), organic molecules and 2D materials are currently used to modify and passivate the buried interface. Li et al. successfully improved the interface using SAM-processed NiOx nanocrystals and effectively bridged the perovskite film. This method created a hole-selective contact, alleviated the interface recombination, and promoted hole extraction, achieving a significant efficiency of 24.7% (certified as 24.4%) in flexible all-perovskite tandem solar cells. Huang et al. used [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACz) to solve the NiOx / FAPbI 3 By reducing the interface defects at the junction and improving the carrier transport, the inverted FAPbI 3 A power conversion efficiency of 23.56% was achieved in the base PSCs. Although the self-assembled monolayer material has improved the power conversion efficiency to a certain extent, there are still problems with wettability, and there are still defects at the interface between the SAM layer and the perovskite absorber layer, which affect the efficiency and stability of the perovskite cell.

[0004] One common way to modify the SAM / perovskite absorber interface is to prepare an interface modification layer on the SAM surface to achieve defect passivation; another way is to add some organic molecules to the perovskite precursor, which reacts with SAM or NiOx to achieve passivation. However, the SAM / perovskite absorber interface passivation by interface modification is not conducive to commercial development, and the preparation process is cumbersome; the effect of adding organic molecules to the perovskite precursor is poor, and the concentration of the additive is difficult to control.

[0005] Therefore, there is an urgent need to develop a new interface modification method with a simple preparation process and excellent photovoltaic performance of perovskite solar cells. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention proposes to achieve uniform distribution of self-assembled monolayer materials by adding 1-hydroxypyrazole to a self-assembled monolayer precursor solution to achieve a passivation effect. At the same time, the hydroxyl group of 1-hydroxypyrazole is hydrophilic, which can effectively increase the wettability of the self-assembled monolayer material, enhance the wettability of the self-assembled monolayer, increase the coverage of perovskite film deposition, facilitate carrier transmission, and further improve the photoelectric conversion efficiency of the perovskite solar cell. The present invention has low material cost and a simple preparation process, which is conducive to commercial promotion.

[0007] Specifically, the present invention provides a hole transport layer, which includes a NiOx layer and a self-assembled monolayer in sequence from a thickness direction; the self-assembled monolayer includes a self-assembled monolayer material and 1-hydroxypyrazole.

[0008] In one or more embodiments, the mass ratio of the self-assembled monolayer material to 1-hydroxypyrazole is 1:(1-20).

[0009] In one or more embodiments, the self-assembled monolayer material is selected from one or more of a self-assembled monolayer material containing a phosphoric acid group and a self-assembled monolayer material containing a carboxylic acid group.

[0010] In one or more embodiments, the self-assembled monolayer material containing phosphate groups is selected from one or more of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, (2-(9H-carbazole-9-yl)ethyl)phosphonic acid and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

[0011] In one or more embodiments, the NiOx layer has a thickness of 10-20 nm.

[0012] In one or more embodiments, the thickness of the self-assembled monolayer is 3-10 nm.

[0013] In one or more embodiments, the hole transport layer has a thickness of 13-30 nm.

[0014] The present invention provides a method for preparing the hole transport layer of the present invention, the method comprising: firstly depositing a NiOx layer, and then depositing a self-assembled monolayer on the surface of the NiOx layer to obtain the hole transport layer.

[0015] In one or more embodiments, the depositing of a self-assembled monolayer on the surface of the NiOx layer includes: preparing a self-assembled monolayer precursor solution containing a self-assembled monolayer material and 1-hydroxypyrazole, coating the self-assembled monolayer precursor solution on the surface of the NiOx layer, and then annealing to obtain the self-assembled monolayer.

[0016] In one or more embodiments, in the self-assembled monolayer precursor solution, the solvent is ethanol and / or isopropanol.

[0017] In one or more embodiments, the concentration of the self-assembled monolayer material in the self-assembled monolayer precursor solution is 0.4-1 mg / mL.

[0018] In one or more embodiments, the concentration of 1-hydroxypyrazole in the self-assembled monolayer precursor solution is 0.05-0.4 mg / mL.

[0019] In one or more embodiments, the annealing temperature is 100-120°C.

[0020] In one or more embodiments, the annealing time is 10-15 min.

[0021] The present invention provides a perovskite solar cell comprising the hole transport layer of the present invention.

[0022] In one or more embodiments, the perovskite solar cell includes a hole transport layer, a perovskite light absorption layer, and an electron transport layer in sequence from a thickness direction.

[0023] The present invention provides a method for preparing the perovskite solar cell of the present invention.

[0024] In one or more embodiments, the method comprises the following steps:

[0025] (1) depositing a perovskite light absorption layer on the surface of the self-assembled monolayer in the hole transport layer;

[0026] (2) Depositing an electron transport layer on the surface of the perovskite light absorbing layer.

[0027] The invention provides use of a hole transport layer in preparing a solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural diagram of a perovskite solar cell prepared according to some embodiments of the present invention, wherein TCO represents a transparent conductive substrate, ETL represents an electron transport layer, PVK represents a perovskite light absorption layer, HTL represents a hole transport layer, and BCP represents a hole blocking layer whose material is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

[0029] Figure 2 This is a scanning electron microscope (SEM) image of the perovskite light absorption layer of the perovskite solar cell without 1-hydroxypyrazole additive prepared in Comparative Example 1.

[0030] Figure 3 This is a scanning electron microscope image (SEM) of the perovskite light absorption layer of the perovskite solar cell containing 1-hydroxypyrazole additive prepared in Example 1. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0033] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0034] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0035] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0036] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] The present invention provides a hole transport layer, which may include a NiOx layer and a self-assembled monolayer in sequence in the thickness direction; the self-assembled monolayer may include a self-assembled monolayer material and 1-hydroxypyrazole. The present invention modifies the buried interface of NiOx-based PSCs by doping 1-hydroxypyrazole in the self-assembled monolayer to improve the coverage of the monolayer; wherein the N atoms in 1-hydroxypyrazole can suppress the interface defects of the SAM / perovskite absorption layer and can coordinate with uncoordinated lead; the hydroxyl group in 1-hydroxypyrazole is hydrophilic, which can effectively increase the wettability of the self-assembled monolayer material, and can obtain a high-quality perovskite film, which is conducive to the improvement of performance, and 1-hydroxypyrazole can also form hydrogen bonds with perovskite to improve the structural stability of perovskite solar cells.

[0039] In the present invention, the mass ratio of the self-assembled monolayer material to 1-hydroxypyrazole can be 1:(1-20), such as 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20. In the present invention, the mass ratio of the self-assembled monolayer material to 1-hydroxypyrazole is controlled within the above range, which is beneficial to improving the short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of the perovskite solar cell.

[0040] In the present invention, the self-assembled monolayer material may be one or more selected from the group consisting of a self-assembled monolayer material containing a phosphoric acid group and a self-assembled monolayer material containing a carboxylic acid group.

[0041] In the present invention, the self-assembled monolayer material containing a phosphate group can be one or more selected from [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid (MeO-2PACZ), (2-(9H-carbazole-9-yl)ethyl)phosphonic acid (2PACZ) and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid (Me-4PACZ).

[0042] In the present invention, the thickness of the NiOx layer can be 10-20 nm, for example, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, and 20 nm.

[0043] In the present invention, the thickness of the self-assembled monolayer can be 3-10 nm, for example, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm.

[0044] In the present invention, the thickness of the hole transport layer may be 13-30 nm, for example, 13 nm, 15 nm, 17 nm, 21 nm, 23 nm, 25 nm, 27 nm, and 29 nm.

[0045] The present invention provides a method for preparing the hole transport layer of the present invention, the method comprising: firstly depositing a NiOx layer, and then depositing a self-assembled monolayer on the surface of the NiOx layer to obtain the hole transport layer.

[0046] In the present invention, the NiOx layer may be deposited by magnetron sputtering.

[0047] In the present invention, depositing a self-assembled monolayer on the surface of a NiOx layer comprises: preparing a self-assembled monolayer precursor solution containing a self-assembled monolayer material and 1-hydroxypyrazole, coating the self-assembled monolayer precursor solution on the surface of the NiOx layer, and then annealing to obtain a self-assembled monolayer.

[0048] In the present invention, the solvent in the self-assembled monolayer precursor solution may be ethanol and / or isopropanol.

[0049] In the present invention, in the self-assembled monolayer precursor solution, the concentration of the self-assembled monolayer material can be 0.4-1 mg / mL, such as 0.4 mg / mL, 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL, 1.0 mg / mL. In the present invention, controlling the concentration of the self-assembled monolayer material within the above range is beneficial to improving the short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of the perovskite solar cell.

[0050] In the present invention, in the self-assembled monolayer precursor solution, the concentration of 1-hydroxypyrazole can be 0.05-0.4 mg / mL, such as 0.05 mg / mL, 0.10 mg / mL, 0.15 mg / mL, 0.20 mg / mL, 0.25 mg / mL, 0.30 mg / mL, 0.35 mg / mL, 0.40 mg / mL. In the present invention, controlling the concentration of 1-hydroxypyrazole within the above range is beneficial to improving the short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of the perovskite solar cell.

[0051] In the present invention, the method of coating the self-assembled monolayer precursor solution may be spin coating.

[0052] In the present invention, the annealing temperature may be 100-120°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C.

[0053] In the present invention, the annealing time can be 10-15 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min.

[0054] The present invention provides a perovskite solar cell comprising the hole transport layer of the present invention.

[0055] In the present invention, the perovskite solar cell may include a hole transport layer, a perovskite light absorption layer and an electron transport layer in sequence in the thickness direction. The present invention modifies the buried interface of NiOx-based PSCs by doping 1-hydroxypyrazole in the self-assembled monolayer precursor solution to improve the coverage of the monolayer; wherein the N atoms in 1-hydroxypyrazole can suppress the SAM / perovskite absorption layer interface defects and can coordinate with uncoordinated lead; the hydroxyl group in 1-hydroxypyrazole can effectively increase the wettability of the self-assembled monolayer material, and can obtain a high-quality perovskite film, which is conducive to the improvement of performance, and 1-hydroxypyrazole can also form hydrogen bonds with perovskite to improve the structural stability of the perovskite solar cell.

[0056] In the present invention, the chemical formula of the perovskite structure material can be ABX 3 , A can be selected from methylamine cation (MA + ), FA + ) and Cs + One or more of, B can be Pb 2+ and / or Sn 2+ , X can be selected from I - Br - and Cl - For example, the perovskite structure material is FAPbI 3 FAMAPbI 3 、FACsPbI 3 or FAMACsPbI 3 .

[0057] In the present invention, the thickness of the perovskite light absorbing layer may be 500-800 nm, for example, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm.

[0058] In the present invention, the electron transport layer material can be selected from one or more of C60 or fullerene derivatives (PCBM), and the fullerene derivative can be [6,6]-phenyl-C61-butyric acid isomethyl ester (

[60] PCBM) or [6,6]-phenyl-C71-butyric acid isomethyl ester (

[70] PCBM).

[0059] In the present invention, the thickness of the electron transport layer may be 15-30 nm, for example, 15 nm, 20 nm, 25 nm, or 30 nm.

[0060] In the present invention, the perovskite solar cell may be a single-junction perovskite solar cell or a stacked perovskite solar cell.

[0061] In some embodiments, the perovskite solar cell includes a transparent conductive substrate, a hole transport layer, a perovskite light absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode in order from the thickness direction. The perovskite solar cell has excellent photovoltaic performance, that is, the short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency of the perovskite solar cell are excellent.

[0062] In the present invention, the material of the transparent conductive substrate layer can be one of fluorine-doped tin oxide (FTO) glass, indium tin oxide (ITO) glass or a flexible indium tin oxide (ITO) conductive substrate.

[0063] In the present invention, the hole blocking layer material can be 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and / or SnO 2 .

[0064] In the present invention, the metal electrode material can be Ag, Cu or Au.

[0065] In the present invention, the thickness of the hole blocking layer may be 4-8 nm, for example, 4 nm, 5 nm, 6 nm, 7 nm, or 8 nm.

[0066] In the present invention, the thickness of the metal electrode may be 60-150 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm.

[0067] The present invention provides a method for preparing the perovskite solar cell of the present invention.

[0068] The method for preparing a perovskite solar cell of the present invention comprises the following steps:

[0069] (1) depositing a perovskite light absorption layer on the surface of the self-assembled monolayer in the hole transport layer;

[0070] (2) Depositing an electron transport layer on the surface of the perovskite light absorbing layer.

[0071] In some embodiments, the method for preparing a perovskite solar cell of the present invention comprises the following steps:

[0072] (a) depositing a NiOx layer on the surface of a transparent conductive substrate and then depositing a self-assembled monolayer to obtain a hole transport layer;

[0073] (b) depositing a perovskite light absorption layer on the surface of the hole transport layer;

[0074] (c) depositing an electron transport layer on the surface of the perovskite light absorbing layer;

[0075] (d) depositing a hole blocking layer on the surface of the electron transport layer;

[0076] (e) depositing a metal electrode on the surface of the hole blocking layer to obtain the perovskite solar cell.

[0077] Step (a) also includes cleaning the transparent conductive substrate and treating it in the UV zone.

[0078] In step (b), a perovskite layer precursor solution is prepared, and the perovskite layer precursor solution is coated on the surface of the hole transport layer, and annealed to obtain a perovskite light absorption layer.

[0079] In step (b), the perovskite layer precursor solution may be coated by spin coating.

[0080] In step (b), the concentration of the theoretically generated perovskite structure material in the perovskite layer precursor solution can be 1.3-1.8 mol / L, for example, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L.

[0081] In step (b), in the perovskite layer precursor solution, the solvent may be one or more selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL) and N-methylpyrrolidone (NMF). In some embodiments, the solvent is selected from two of N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone and N-methylpyrrolidone, and the volume ratio of the two organic solvents is (3-5):1. For example, the solvent may be a mixture of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of (3-5):1, the solvent may also be a mixture of γ-butyrolactone and N-methylpyrrolidone in a volume ratio of (3-5):1, and the solvent may also be a mixture of N,N-dimethylformamide and N-methylpyrrolidone in a volume ratio of (3-5):1.

[0082] In step (b), the annealing temperature may be 100-150°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C.

[0083] In step (b), the annealing time can be 10-35 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min.

[0084] In step (c), the electron transport layer may be deposited by thermal evaporation.

[0085] In step (d), the hole blocking layer may be deposited by thermal evaporation.

[0086] In step (e), the metal electrode may be deposited by thermal evaporation.

[0087] The invention provides use of a hole transport layer in preparing a solar cell.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] (1) The present invention modifies the buried interface of NiOx-based PSCs by doping 1-hydroxypyrazole in the self-assembled monolayer precursor solution to improve the coverage of the monolayer; wherein the N atoms in 1-hydroxypyrazole can suppress the interface defects of the SAM / perovskite absorber layer and can coordinate with uncoordinated lead; the hydroxyl groups in 1-hydroxypyrazole can effectively increase the wettability of the self-assembled monolayer material, and can obtain a high-quality perovskite film, which is beneficial to the performance improvement; 1-hydroxypyrazole can also form hydrogen bonds with perovskite to improve the structural stability of the perovskite solar cell;

[0090] (2) The material cost required for the present invention is relatively low, which is conducive to commercial promotion;

[0091] (3) The preparation process of the present invention is simple.

[0092] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples can all be purchased through commercial routes.

[0093] Example 1

[0094] This example was prepared according to the following steps: Figure 1 Perovskite solar cell shown:

[0095] (1) Cleaning the transparent conductive substrate: placing the FTO substrate in an ultrasonic cleaning device, and cleaning the FTO substrate with detergent water, deionized water, and ethanol in sequence, with each cleaning step lasting 20 minutes, and drying with nitrogen before use. The ultrasonically cleaned FTO substrate is treated in the UV zone for 20 minutes to obtain a clean transparent conductive substrate;

[0096] (2) Preparation of hole transport layer: magnetron sputtering of 15 nm NiOx layer on a clean transparent conductive substrate by radio frequency sputtering; first preparing 2 mL of 0.6 mg / mL self-assembled monolayer material solution, wherein the solute is Me-4PACZ and the solvent is ethanol, then adding 1-hydroxypyrazole to the self-assembled monolayer material solution, stirring evenly, to obtain a self-assembled monolayer precursor solution with a 1-hydroxypyrazole concentration of 0.2 mg / mL; using a spin coating method to spin-coat the self-assembled monolayer precursor solution on the surface of the NiOx layer, the spin coating speed is 3000 rpm, and then annealing at 100°C for 10 min to obtain a self-assembled monolayer with a thickness of 5 nm. The NiOx layer and the self-assembled monolayer together constitute the hole transport layer;

[0097] (3) Preparation of perovskite light absorption layer: 1.6 mmol of FAPbI 3 The perovskite solution was dissolved in 1 mL of a mixed solvent of DMF and NMP with a volume ratio of 4:1, and stirred for 2 h to obtain a perovskite precursor solution; the perovskite precursor was spin-coated and deposited on the surface of the hole transport layer using a one-step spin coating method, with a spin coating speed of 5000 rpm and a spin coating time of 30 s. 300 μL of anisole was quickly added 5 s before the end of the spin coating deposition to obtain a perovskite wet film, which was annealed at 150° C. for 10 min to obtain a perovskite light absorption layer with a thickness of 560 nm;

[0098] (4) Preparation of electron transport layer: On the surface of the prepared perovskite light absorption layer 30nm C60 was deposited by thermal evaporation to obtain an electron transport layer;

[0099] (5) Preparation of hole blocking layer: On the surface of the prepared electron transport layer Thermal evaporation was used to deposit 6 nm BCP to obtain a hole blocking layer.

[0100] (6) Preparing a metal electrode; thermally evaporating 110 nm of Ag on the surface of the prepared hole blocking layer to prepare a metal electrode and simultaneously obtain a perovskite solar cell.

[0101] Example 2

[0102] The other conditions of this example are the same as those of Example 1, except that the concentration of 1-hydroxypyrazole is replaced from 0.2 mg / mL to 0.05 mg / mL in this example.

[0103] Example 3

[0104] The other conditions of this example are the same as those of Example 1, except that the concentration of 1-hydroxypyrazole is replaced from 0.2 mg / mL to 0.4 mg / mL in this example.

[0105] Comparative Example 1

[0106] The other conditions of this comparative example are the same as those of Example 1, except that 1-hydroxypyrazole is not added in this comparative example.

[0107] Test Case

[0108] Perovskite solar cell performance test: Under the 1.5G standard solar spectrum, a solar simulator was used to set the voltage range to -0.1-1.25V, and the current output of the perovskite solar cells prepared in Examples 1-3 and Comparative Example 1 at different voltages was tested, and the corresponding current-voltage (IV) characteristic curves were plotted, where the cell surface area was 0.0706cm 2 , the incident light power (Pin) is 100mW / cm 2 .

[0109] (1) Short-circuit current density (Jsc): The current value when the voltage is zero is the short-circuit current (Isc), and the current per unit battery surface area is the short-circuit current density.

[0110] (2) Open circuit voltage (Voc): The voltage value corresponding to when the current is equal to zero.

[0111] (3) Fill factor (FF): The ratio of the maximum output power (Pmax) of the battery to the product of the open circuit voltage and the short circuit current. The calculation formula is (Pmax / Voc*Isc), where the maximum power point is the point where the battery output power reaches its maximum value.

[0112] (4) Photoelectric conversion efficiency (PCE): Photoelectric conversion efficiency refers to the ratio of maximum output power to incident light power (Pin), and the calculation formula is (Pmax / Pin)*100%.

[0113] The short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of the perovskite solar cells prepared in Examples 1-3 and Comparative Example 1 were obtained according to the IV curves.

[0114] Table 1: Short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency of perovskite solar cells prepared in Examples 1-3 and Comparative Example 1

[0115]

[0116]

[0117] Depend on Figure 2 It can be seen that the perovskite light absorption layer prepared on the surface of the self-assembled monolayer without 1-hydroxypyrazole additive has many holes, which will seriously affect the performance of the device. Figure 3 It can be seen that the perovskite light absorption layer prepared on the surface of the self-assembled monolayer containing 1-hydroxypyrazole additive is denser and has no holes.

[0118] It can be seen from Table 1 that compared with the perovskite solar cell prepared without adding 1-hydroxypyrazole in Comparative Example 1, the perovskite solar cells prepared by adding 1-hydroxypyrazole in Examples 1-3 of the present invention have higher short-circuit current density, open-circuit voltage, fill factor and photoelectric conversion efficiency, which further illustrates that the perovskite solar cell prepared by adding 1-hydroxypyrazole in the present invention has excellent photovoltaic performance.

Claims

1. A hole transport layer, characterized in that: The hole transport layer includes a NiOx layer and a self-assembled monolayer in sequence from a thickness direction; the self-assembled monolayer includes a self-assembled monolayer material and 1-hydroxypyrazole.

2. The hole transport layer according to claim 1, characterized in that The hole transport layer has one or more of the following characteristics: The mass ratio of the self-assembled monolayer material to 1-hydroxypyrazole is 1:(1-20); The self-assembled monolayer material is selected from one or more of a self-assembled monolayer material containing a phosphoric acid group and a self-assembled monolayer material containing a carboxylic acid group; The thickness of the NiOx layer is 10-20 nm; The thickness of the self-assembled monolayer is 3-10 nm; The thickness of the hole transport layer is 13-30 nm.

3. The hole transport layer according to claim 2, characterized in that The self-assembled monolayer material containing phosphoric acid groups is selected from one or more of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid, (2-(9H-carbazole-9-yl)ethyl)phosphonic acid and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

4. A method for preparing a hole transport layer according to any one of claims 1 to 3, characterized in that: The method comprises: firstly depositing a NiOx layer, and then depositing a self-assembled monomolecular layer on the surface of the NiOx layer to obtain the hole transport layer.

5. The method according to claim 4, characterized in that The method of depositing a self-assembled monolayer on the surface of the NiOx layer comprises: preparing a self-assembled monolayer precursor solution containing a self-assembled monolayer material and 1-hydroxypyrazole, coating the self-assembled monolayer precursor solution on the surface of the NiOx layer, and then annealing to obtain the self-assembled monolayer.

6. The method according to claim 5, characterized in that The method has one or more of the following features: In the self-assembled monolayer precursor solution, the solvent is ethanol and / or isopropanol; In the self-assembled monolayer precursor solution, the concentration of the self-assembled monolayer material is 0.4-1 mg / mL; In the self-assembled monolayer precursor solution, the concentration of 1-hydroxypyrazole is 0.05-0.4 mg / mL; Annealing temperature is 100-120°C; The annealing time is 10-15 minutes.

7. A perovskite solar cell comprising the hole transport layer according to any one of claims 1 to 3.

8. The perovskite solar cell according to claim 7, characterized in that The perovskite solar cell includes a hole transport layer, a perovskite light absorption layer and an electron transport layer in sequence from the thickness direction.

9. A method for preparing the perovskite solar cell according to claim 7 or 8, characterized in that: The method comprises the following steps: (1) depositing a perovskite light absorption layer on the surface of the self-assembled monolayer in the hole transport layer; (2) Depositing an electron transport layer on the surface of the perovskite light absorbing layer.

10. Use of the hole transport layer according to any one of claims 1 to 3 in preparing a solar cell.

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