Hole transport material, preparation method thereof and perovskite solar cell

Abstract

The invention discloses a hole transport material, a preparation method thereof and a perovskite solar cell, the hole transport material has a structure as shown in a formula 1, and the preparation method of the hole transport material comprises the following steps: S1, adding 4, 5-dichlorophthalonitrile, phenylacetylene and a catalyst into a solvent for mixing, performing a first heating reflux reaction in an inert atmosphere to obtain a product as shown in a formula 2; and S2, mixing the product as shown in the formula 2, boron trichloride and an organic solvent, and carrying out a second heating reflux reaction in an inert atmosphere to prepare the hole transport material. According to the hole transport material, subphthalocyanine is used as a core skeleton, modification is carried out through peripheral phenylacetylene groups, a pi conjugated system is remarkably expanded while the basic structure of subphthalocyanine is maintained, and therefore the photoelectric conversion efficiency of a perovskite solar cell is improved; in addition, the hole transport material is good in thermal and chemical stability and has hydrophobicity, so that the service life of the perovskite solar cell is prolonged, and the stability of the perovskite solar cell is improved.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and particularly relates to a hole transport material, its preparation method, and a perovskite solar cell. Background Technology

[0002] While the photoelectric conversion efficiency of perovskite solar cells has reached commercial standards, their practical applications remain limited by battery life and stability. In perovskite solar cells, the hole transport layer plays a crucial role in cell performance and lifespan. This is because it extracts hole carriers from the perovskite active layer, prevents hole-electron recombination at the interface, transports hole carriers to the electrodes, and prevents water and oxygen intrusion into the perovskite active layer. Therefore, selecting suitable hole transport materials to fabricate a high-performance hole transport layer is key to improving cell performance. An ideal hole transport material must possess characteristics such as high carrier mobility, excellent thermal and chemical stability, good film-forming properties, suitable HOMO / LUMO energy levels and band gap, good hydrophobicity, and low cost.

[0003] Currently used hole transport materials can be broadly classified into three categories based on their structure and composition: inorganic hole transport materials, organic polymer hole transport materials, and organic small molecule hole transport materials. Compared to inorganic and organic polymer hole transport materials, organic small molecules have attracted widespread attention due to their definite molecular structures, relatively simple preparation and purification, and easily tunable energy levels. Most commonly used organic small molecule hole transport materials are prepared by the reaction of spirofluorene and aniline, with Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) being a typical example. However, these materials are expensive, limiting their widespread application. Furthermore, these materials typically have poor conductivity, requiring the doping of with additives such as lithium metal salts to improve conductivity. However, these additives are hygroscopic, which can severely affect battery life and stability.

[0004] Therefore, there is an urgent need for a hole transport material and its preparation method, as well as perovskite solar cells, to address the shortcomings of existing technologies. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a hole transport material, a method for preparing the same, and a perovskite solar cell. This hole transport material can improve the photoelectric conversion efficiency, stability, and lifespan of perovskite solar cells.

[0006] To achieve the above objectives, the first aspect of the present invention provides a hole transport material having the structure shown in Formula 1:

[0007] Formula 1.

[0008] Compared with existing technologies, the hole transport material of the present invention has the structure shown in Formula 1. This material uses phthalocyanine as the core framework and is modified by peripheral phenylacetylene groups. While maintaining the basic structure of phthalocyanine, it significantly expands the π-conjugated system and increases the delocalization of π electrons, thereby improving the carrier mobility of the hole transport material. Simultaneously, it makes the energy levels of the material and the perovskite active layer more well-matched, effectively improving the carrier extraction efficiency and reducing the probability of hole-electron recombination, thus improving the photoelectric conversion efficiency of the perovskite solar cell. Furthermore, the molecular structure shown in Formula 1 of the present invention has good thermal and chemical stability and is hydrophobic. Using it to prepare the hole transport layer of a perovskite solar cell can effectively protect the perovskite light-absorbing layer and reduce the erosion of environmental factors (such as moisture), thereby improving the lifetime and stability of the perovskite solar cell.

[0009] Accordingly, a second aspect of the present invention provides a method for preparing the above-mentioned hole transport material, comprising the steps of: S1. 4,5-Dichlorophthalonitrile, phenylacetylene and catalyst are added to a solvent and mixed. The mixture is subjected to a first heating reflux reaction under an inert atmosphere, and then subjected to a first cooling treatment and a first purification treatment to obtain the product shown in Formula 2. S2. The product shown in Formula 2 and the organic solution of boron trichloride are mixed and subjected to a second heating reflux reaction under an inert atmosphere. The mixture is then subjected to a second cooling treatment and a second purification treatment to obtain the hole transport material.

[0010] Compared with the prior art, the present invention prepares the product shown in Formula 2 by reacting a mixture of 4,5-dichlorophthalonitrile and phenylacetylene, and then reacts the product shown in Formula 2 with boron trichloride to obtain the hole transport material. Therefore, the preparation method provided by the present invention has simple preparation steps, is easy to industrialize, and uses inexpensive raw materials.

[0011] Furthermore, the catalyst of the present invention comprises bis(triphenylphosphine)palladium dichloride and cuprous iodide.

[0012] Furthermore, the conditions for the first heating reflux reaction in step S1 of the present invention are: reacting at 60~90°C for 8~72 hours.

[0013] Furthermore, in step S1 of the present invention, the molar ratio of 4,5-dichlorophthalonitrile to phenylacetylene is 1:1 to 1:2.

[0014] Furthermore, the first purification process in step S1 of the present invention includes filtration and washing, column chromatography separation, concentration, and recrystallization in sequence.

[0015] Furthermore, the conditions for the second heating reflux reaction in step S2 of the present invention are: reacting at 130~150°C for 5~30 min.

[0016] Furthermore, in step S2 of the present invention, the molar ratio of the compound shown in Formula 2 to boron trichloride is 3:1 to 1:3.

[0017] Accordingly, a third aspect of the present invention provides a perovskite solar cell, comprising a substrate layer, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and an electrode layer stacked together, wherein the hole transport layer is made of the hole transport material mentioned above or a hole transport material prepared by the method mentioned above.

[0018] Compared with the prior art, the material of the hole transport layer in the perovskite solar cell of the present invention can improve the extraction efficiency of hole carriers, block electrons from entering the hole transport layer, reduce the probability of hole-electron recombination, and prevent moisture intrusion. Therefore, the perovskite solar cell of the present invention has higher photoelectric conversion efficiency, lifetime and stability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the perovskite solar cell structure of the present invention.

[0020] Figure 2 This is a SEM image of the hole transport layer of a perovskite solar cell containing the hole transport material of Example 1.

[0021] Figure 3 The image shows the IV curve of a perovskite solar cell containing the hole transport material of Example 1.

[0022] Figure 4 The graph shows the change in photoelectric conversion efficiency of perovskite solar cells containing the hole transport materials of Example 1 and Comparative Example 1 in air over time. Detailed Implementation

[0023] Please refer to Figure 1 This invention provides a perovskite solar cell 100, comprising a substrate layer 11, an electron transport layer 12, a perovskite light-absorbing layer 13, a hole transport layer 14, and an electrode layer 15 stacked together. The hole transport layer 14 is made of a material with the structure shown in Formula 1. The material of the hole transport layer 14 in the perovskite solar cell 100 of this invention can improve the extraction efficiency of hole carriers, block electrons from entering the hole transport layer 14, reduce the probability of hole-electron recombination, and prevent moisture intrusion. Therefore, the perovskite solar cell 100 of this invention has good photoelectric conversion efficiency, lifetime, and stability.

[0024] Furthermore, the thickness of the substrate layer 11 of the present invention is 10~30 nm. Specifically, the thickness of the substrate layer 11 may be, but is not limited to, 10 nm, 12 nm, 16 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, or 30 nm. More specifically, the substrate layer 11 may be prepared from indium tin oxide (ITO) or fluorine-doped tin dioxide (FTO).

[0025] Furthermore, the thickness of the electron transport layer 12 of the present invention is 10~30 nm. Specifically, the thickness of the electron transport layer 12 may be, but is not limited to, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, or 30 nm. More specifically, the electron transport layer 12 may be made of tin dioxide.

[0026] Further, the thickness of the perovskite light-absorbing layer 13 of the present invention is 100~800 nm. Specifically, the thickness of the perovskite light-absorbing layer 13 can be, but is not limited to, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, and 800 nm. More specifically, the perovskite light-absorbing layer 13 can be made of CH3NH3PbI3 or CH3NH3-xPbCl. x preparation.

[0027] Furthermore, the thickness of the electrode layer 15 of the present invention is 50~150 nm. Specifically, the thickness of the electrode layer 15 can be, but is not limited to, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, and 150 nm. Specifically, the electrode layer 15 can be made of gold; however, the material used to prepare the electrode layer 15 is not limited to this, and can also be silver, aluminum, etc.

[0028] It is worth noting that the fabrication methods of the perovskite solar cells involved in this invention, such as the fabrication steps of the substrate layer 11, the electron transport layer 12, the perovskite light-absorbing layer 13, and the electrode layer 15, are conventional methods known to those skilled in the art, and therefore will not be described in detail here.

[0029] Furthermore, the thickness of the hole transport layer 14 of the present invention is 50~150 nm. Specifically, the thickness of the hole transport layer 14 can be, but is not limited to, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, and 150 nm. More specifically, the hole transport layer 14 can be prepared by vacuum evaporation using the hole transport material shown in Formula 1. Furthermore, to facilitate understanding of how the hole transport layer 14 functions in the perovskite solar cell 100, the hole transport material and its preparation method will be described in more detail below.

[0030] Furthermore, this invention employs a compound having the structure shown in Formula 1 as a hole transport material.

[0031] Formula 1 This hole transport material uses phthalocyanine as its core framework and is modified with peripheral phenylacetylene groups. While maintaining the basic structure of phthalocyanine, it significantly expands the π-conjugated system, increases the delocalization of π electrons, and thus improves the carrier mobility of the hole transport material. Simultaneously, it makes the energy levels of the material more matched with the perovskite active layer, effectively improving carrier extraction efficiency and reducing the probability of hole-electron recombination, thereby improving the photoelectric conversion efficiency of perovskite solar cells. Furthermore, the molecular structure shown in Formula 1 of this invention exhibits good thermal and chemical stability and is hydrophobic. Using it to prepare the hole transport layer of a perovskite solar cell can effectively protect the perovskite light-absorbing layer and reduce the erosion of environmental factors (such as moisture), thereby improving the lifetime and stability of the perovskite solar cell.

[0032] Accordingly, the preparation method of the hole transport material includes the following steps: S1. 4,5-Dichlorophthalonitrile (CAS: 139152-08-2), phenylacetylene (CAS: 536-74-3) and catalyst are added to a solvent and mixed. The mixture is subjected to a first heating reflux reaction under an inert atmosphere, and then subjected to a first cooling treatment and a first purification treatment to obtain the product shown in Formula 2. S2. The product shown in Formula 2 is mixed with an organic solution of boron trichloride (CAS: 10294-34-5) and subjected to a second heating reflux reaction under an inert atmosphere. The mixture is then subjected to a second cooling treatment and a second purification treatment to obtain the hole transport material.

[0033] The chemical reaction equation in step S1 is shown below:

[0034] The catalyst of this invention comprises palladium dichloride bis(triphenylphosphine) (CAS: 13965-03-2) and cuprous iodide (CAS: 7681-65-4). Specifically, the molar ratio of palladium dichloride bis(triphenylphosphine) to cuprous iodide is 0.8~1.2:0.8~1.2. Preferably, the molar ratio of palladium dichloride bis(triphenylphosphine) to cuprous iodide is 1:1.

[0035] The solvents used in this invention are triethylamine and anhydrous tetrahydrofuran.

[0036] In step S1 of the present invention, the inert atmosphere is argon (Ar).

[0037] In step S1 of this invention, the conditions for the first reflux reaction are: reacting at 60-90°C for 8-72 hours. Specifically, the temperature of the first reflux reaction can be, but is not limited to, 60°C, 70°C, 80°C, 85°C, or 90°C; the time of the first reflux reaction can be, but is not limited to, 8 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 68 hours, or 72 hours.

[0038] In step S1 of this invention, the molar ratio of 4,5-dichlorophthalonitrile to phenylacetylene is 1:1 to 1:2. Specifically, the molar ratio of 4,5-dichlorophthalonitrile to phenylacetylene can be, but is not limited to, 1:1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.7, 1:1.8, 1:1.9, or 1:2.

[0039] In step S1 of the present invention, the cooling process is: natural cooling to room temperature.

[0040] In this invention, step S1, the first purification process, sequentially includes filtration and washing, column chromatography separation, concentration, and recrystallization. Specifically, organic solvents (such as dichloromethane, chloroform, methanol, ethanol, ethyl acetate, formonitrile, acetone, n-hexane, cyclohexane, petroleum ether, etc.) can be used for filtration and washing. Column chromatography separation is a conventional operation in the art; for example, a chromatographic column can be packed with SiO2 or Al2O3, and a mixture of dichloromethane and petroleum ether can be used as the eluent. Specifically, concentration is also a conventional operation in the art; for example, a rotary evaporator can be used for concentration. Recrystallization is also a conventional operation in the art, and the reagents used can be a mixture of ethanol and dichloromethane or a mixture of ethanol and chloroform, etc.

[0041] The chemical reaction equation in step S2 is shown below:

[0042] In step S2 of the present invention, the conditions for the second heating reflux reaction are: reacting at 130~150°C for 5~30 min. Specifically, the temperature of the second heating reflux reaction can be, but is not limited to, 130°C, 135°C, 140°C, 145°C, or 150°C; the time of the second heating reflux reaction can be, but is not limited to, 5 min, 8 min, 10 min, 15 min, 19 min, 22 min, 24 min, 26 min, 28 min, or 30 min.

[0043] In step S2 of this invention, the molar ratio of the compound shown in Formula 2 to boron trichloride is 3:1 to 1:3. Specifically, the molar ratio of the compound shown in Formula 2 to boron trichloride can be, but is not limited to, 3:1, 2:1, 1:1, 1:2, or 1:3.

[0044] In step S2 of this invention, the organic solution of boron trichloride is a boron trichloride-p-xylene solution. Since boron trichloride (BCl3) is gaseous at room temperature and pressure and cannot be directly used in liquid-phase reactions, it needs to be dissolved in an organic solvent to form a stable solution. Specifically, gaseous boron trichloride can be passed into a p-xylene solution to prepare a 1 M boron trichloride-p-xylene solution, i.e., each liter of p-xylene contains 1 mol (approximately 117.17 g) of BCl3. This solution is stable, easy to store safely, and allows for precise measurement.

[0045] In step S2 of the present invention, the inert atmosphere is argon (Ar).

[0046] In step S2 of this invention, the second purification process sequentially includes filtration and washing. Specifically, an organic solvent (such as dichloromethane, chloroform, methanol, ethanol, ethyl acetate, formonitrile, acetone, n-hexane, cyclohexane, petroleum ether, etc.) can be used for preliminary filtration and washing to obtain a crude product. The crude product can then be further purified by washing with a Soxhlet extractor, using organic solvents such as dichloromethane, chloroform, methanol, ethanol, ethyl acetate, etc., and the filtration and washing operations are conventional methods in the art.

[0047] In step S2 of the present invention, the cooling process is: natural cooling to room temperature.

[0048] To illustrate the purpose, technical solution, and beneficial effects of the present invention in more detail, the following description will be provided in conjunction with specific embodiments.

[0049] Example 1 This embodiment provides a hole transport material having the structure shown in Formula 1:

[0050] The method for preparing hole transport materials provided in this embodiment includes the following steps: S1, 1.97g (10mmol) of 4,5-dichlorophthalonitrile, 2.45g (24mmol) of phenylacetylene, 0.084 g (0.12 mmol) of bis(triphenylphosphine)palladium dichloride, 0.023 g (0.12 mmol) of cuprous iodide, 30 ml of triethylamine, and 60 ml of anhydrous tetrahydrofuran were placed in a 250 ml double-necked round-bottom flask to obtain the first mixture. A magnetic rotor was placed inside, the flask was stoppered, and a condenser was connected. A gas nozzle was attached to the end of the condenser, and the gas nozzle was also connected to a double-row tube. The first mixture was stirred under Ar protection and heated to reflux at 80 °C for 36 h, then cooled to room temperature to obtain the second mixture. The second mixture was filtered and then subjected to dichloromethane (30 ml × 3) Wash the solid on the filter paper and collect the filtrate; remove the solvent from the filtrate using a rotary evaporator to obtain a crude solid product; purify the crude solid product using column chromatography to obtain a purified solid product, wherein the stationary phase used to pack the column is SiO2, and the eluent is a mixed solvent of dichloromethane and petroleum ether (v / v=1 / 3); further purify the purified solid product by recrystallization, using a mixed solvent of ethanol / dichloromethane, and recrystallize three times to obtain the compound shown in Formula 2; the 1H NMR spectrum of the compound shown in Formula 2 is: 1H NMR (CDCl3, 400 MHz) δ 7.38-7.45 (m, 6H), 7.60 (d, 4H, J = 7.6Hz), 7.93 (s, 2H), indicating that the compound shown in Formula 2 was successfully synthesized. (2) 1.64 g (5 mmol) of the product of Formula 2 and 10 mL of boron trichloride in p-xylene solution (1 M, containing 1.17 g, 7.5 mmol of boron trichloride) were placed in a 50 mL single-necked round-bottom flask to obtain the third mixture. A magnetic rotor was placed in the flask, and a condenser was connected to it. A gas nozzle was connected to the end of the condenser and a double-row tube was connected to it. The third mixture was stirred under Ar protection and heated under reflux at 150 °C for 10 min. Then it was cooled to room temperature to obtain the fourth mixture. The fourth mixture was filtered, and the solid on the filter paper was washed with dichloromethane (30 mL × 3). The solid on the filter paper was collected and air-dried to obtain the solid. The solid was washed and purified using a Soxhlet extractor with ethanol as the organic solvent to obtain the hole transport material shown in Formula 1. The molecular ion peak was detected by mass spectrometry (ESI-MS): m / z (M + ) 1030.32; This indicates that the hole transport material shown in Formula 1 was successfully synthesized.

[0051] Comparative Example 1 This comparative example uses Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) as the hole transport layer material.

[0052] This comparative example provides a method for preparing a hole transport layer material, including the following steps: (1) Prepare a chlorobenzene solution of Spiro-OMeTAD at a concentration of 100 mg / mL in an Ar atmosphere. (2) Add 15.92 ml of 4-tert-butylpyridine and 9.68 ml of lithium bis(trifluoromethanesulfonyl)imide at a concentration of 520 mg / ml directly to 0.3 ml of the solution obtained in step (1).

[0053] Comparative Example 2 This comparative example provides a hole transport material having the structure shown in Formula 3, which can be prepared by referring to the method disclosed in CN117156906A.

[0054]

[0055] Formula 3 Comparative Example 3 This comparative example provides a hole transport material having the structure shown in Formula 4, which can be prepared by referring to the method disclosed in CN117156906A.

[0056]

[0057] Formula 4 The hole transport materials of Examples 1 and Comparative Examples 1-3 were applied to perovskite solar cells according to the following method for preparing perovskite solar cells.

[0058] Methods for fabricating perovskite solar cells: (1) Preparation of FTO substrate layer The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 15 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 100℃ for 10 h. Then it was treated with ultraviolet / ozone for 30 min to obtain the FTO substrate layer.

[0059] (2) Preparation of tin dioxide electron transport layer A 0.1 mol / L stannous chloride (SnCl2•2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 40 s. The resulting film was then annealed in air at 180 °C for 1 h to obtain a tin dioxide electron transport layer with a thickness of 15 nm.

[0060] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer In an argon atmosphere, 461 mg of lead iodide (PbI2), 159 mg of methyl ammonium iodide (CH3NH3I), and 78 mg of dimethyl sulfoxide (DMSO) were mixed and dissolved in 600 mg of dimethylformamide (DMF). The mixture was stirred at room temperature for 1 h to form a solution. 100 μL of this solution was spin-coated onto a tin dioxide electron transport layer using a spin coater at 4000 rpm for 20 s. During spin coating, 0.5 ml of diethyl ether or 0.3 ml of chlorobenzene was added to improve the film quality. The resulting CH3NH3PbI3 film was then annealed sequentially at 65 °C for 2 min and at 100 °C for 5 min to obtain a CH3NH3PbI3 perovskite light-absorbing layer with a thickness of 600 nm.

[0061] (4) Preparation of hole transport layer Hole transport layers were prepared on the surface of the perovskite light-absorbing layer using vacuum thermal evaporation of the hole transport materials from Examples 1, 2, and 3, with a vacuum degree of 1 × 10⁻⁶. -6 Pa, evaporation rate 0.2~0.8 Å / s, and hole transport layer thickness controlled at 80 nm.

[0062] A hole transport layer was prepared on the surface of the perovskite light-absorbing layer using a liquid phase spin coating method. Specifically, the hole transport material was spin-coated onto the perovskite light-absorbing layer using a spin coater at a speed of 4000 rpm for 45 s, and the thickness of the Spiro-OMeTAD hole transport layer was controlled to be 80 nm.

[0063] (5) Fabrication of gold electrode layer A gold electrode layer was prepared on the surface of the hole transport layer using a vacuum thermal evaporation method with a vacuum degree of 1×10⁻⁶. -6 Perovskite solar cells were fabricated by using a deposition rate of 0.2~0.8 Å / s and controlling the electrode layer thickness to be 100 nm.

[0064] The morphology of the hole transport layer in the perovskite solar cell of Example 1 was observed using scanning electron microscopy, and the results are as follows: Figure 2 As shown.

[0065] Depend on Figure 2 It can be seen that the hole transport layer made from the hole transport material of the present invention has a regular, continuous and compact morphology.

[0066] The performance of the above-mentioned perovskite solar cell was tested using conventional methods in the art, and the effective area of ​​the cell device was 0.08 cm². 2Spectral distribution AM1.5G, illuminance 100mW / cm² 2 All devices are simply encapsulated with UV adhesive, and the tests show normal measurement in an atmospheric environment.

[0067] During the test, it was found that the perovskite solar cells of Comparative Examples 2 and 3 showed an abnormality with a comprehensive decrease in open-circuit voltage, fill factor, and current density, as well as significant hysteresis. This indicates that although the materials shown in Equations 3 and 4 also contain subphthalocyanine structures, these two materials cannot be used as hole transport materials. The reason why they cannot be used as hole transport layers is that their energy levels are mismatched. Their HOMO energy levels are too deep, which is not conducive to the extraction and transport of hole carriers.

[0068] Figure 3 The IV curves are shown for the perovskite solar cell containing the hole transport material of Example 1. According to the obtained IV curves, the open-circuit voltage of the perovskite solar cell containing the hole transport material of Example 1 is 1.05V, and the short-circuit current density is 21.64mA / cm². 2 The fill factor is 77% and the power conversion efficiency (PCE) is 17.53%. This also shows that using the compound shown in Formula 1 as the hole transport material as the transport layer of the perovskite solar cell can ensure that the perovskite solar cell has good open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency.

[0069] Figure 4 This is a graph showing the change in photoelectric conversion efficiency over time of perovskite solar cells containing the hole transport materials of Example 1 and Comparative Example 1 in air. Figure 4 It can be seen that the perovskite solar cell containing the hole transport material of Example 1 still maintains more than 85% of its initial efficiency after being stored in the atmosphere for 800 hours. However, the device efficiency of the perovskite solar cell containing the hole transport material of Comparative Example 1 decays significantly in the atmosphere. After 800 hours, the efficiency drops to less than 50% of the initial efficiency. This also indicates that the hole transport material of traditional perovskite solar cells has poor stability due to the introduction of lithium metal salt dopants.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A hole transport material, characterized in that, It has the structure shown in Equation 1: Formula 1.

2. A method for preparing a hole transport material as described in claim 1, characterized in that, step include: S1. 4,5-Dichlorophthalonitrile, phenylacetylene and catalyst are added to a solvent and mixed. The mixture is subjected to a first heating reflux reaction under an inert atmosphere, and then subjected to a first cooling treatment and a first purification treatment to obtain the product shown in Formula 2. S2. The product shown in Formula 2 and the organic solution of boron trichloride are mixed and subjected to a second heating reflux reaction under an inert atmosphere. The mixture is then subjected to a second cooling treatment and a second purification treatment to obtain the hole transport material.

3. The method for preparing the hole transport material as described in claim 2, characterized in that, The catalyst described in step S1 includes bis(triphenylphosphine)palladium dichloride and cuprous iodide.

4. The method for preparing the hole transport material as described in claim 2, characterized in that, The conditions for the first heating reflux reaction in step S1 are: reacting at 60~90℃ for 8~72h.

5. The method for preparing the hole transport material as described in claim 2, characterized in that, In step S1, the molar ratio of 4,5-dichlorophthalonitrile to phenylacetylene is 1:1 to 1:

2.

6. The method for preparing the hole transport material as described in claim 2, characterized in that, The first purification process in step S1 includes filtration and washing, column chromatography separation, concentration, and recrystallization in sequence.

7. The method for preparing the hole transport material as described in claim 2, characterized in that, The conditions for the second heating reflux reaction in step S2 are: reacting at 130~150℃ for 5~30 min.

8. The method for preparing the hole transport material as described in claim 2, characterized in that, In step S2, the molar ratio of the compound shown in Formula 2 to the boron trichloride is 3:1 to 1:

3.

9. A perovskite solar cell, characterized in that, The invention comprises a substrate layer, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode layer stacked together, characterized in that the hole transport layer is made of the hole transport material as described in claim 1 or the hole transport material prepared by the method described in any one of claims 2 to 8.

10. The perovskite solar cell according to claim 9, characterized in that, The thickness of the hole transport layer is 50~150nm.

Images