Perovskite solar cell and hole transport material thereof

Abstract

The application belongs to the technical field of perovskite solar cells, and particularly relates to a perovskite solar cell and a hole transport material thereof, wherein the hole transport material is specifically a phenanthroline metal complex, has the structural formula shown in the following formula (I), is low in cost, and can be used in the perovskite solar cell to improve device stability.

Description

Technical Field

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

[0002] The overexploitation and use of fossil fuels has seriously impacted the sustainable development of human society. A viable alternative is the use of renewable and clean energy. Photovoltaic power generation, as a clean, renewable, flexible, and efficient energy form, has broad application prospects.

[0003] As a rising star in the photovoltaic family, perovskite solar cells have developed rapidly over the past decade. Currently, their photoelectric conversion efficiency is close to the commercial standard, but the stability of device performance and the relatively high manufacturing cost still restrict this emerging technology from entering the market.

[0004] The hole transport layer, an indispensable component of perovskite solar cells, plays a crucial role in optimizing the interface, extracting and transporting hole carriers, and protecting the perovskite light-absorbing layer. The properties of the hole transport layer significantly impact the lifetime and stability of perovskite solar cells.

[0005] Currently, most high-efficiency perovskite solar cells are based on hole transport layers made from organic small-molecule semiconductor materials. These organic small molecules are typically obtained by reacting spirofluorene and aniline, which is expensive and hinders widespread application. Furthermore, these materials have low conductivity, requiring the addition of lithium salts to improve their conductivity, which in turn reduces the cell's lifespan and stability. Therefore, it is urgent to solve the problems of high cost and poor performance of hole transport materials in perovskite solar cells.

[0006] In view of this, the present invention aims to provide a perovskite solar cell and its hole transport material, which innovatively uses a low-cost phenanthroline metal complex as the hole transport material, which can improve the stability of the battery device. Specifically, the phenanthroline metal complex has excellent semiconductor properties and good solubility in organic solvents, and can be used to prepare a doped hole transport layer for a perovskite solar cell using a low-cost liquid-phase spin-coating process; the halide ions in the metal complex can interact with the incompletely coordinated Pb on the surface of the light-absorbing layer. 2+ The ions form chemical interactions, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic methyl (-CH3) groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device. Summary of the Invention

[0007] One objective of this invention is to address the shortcomings of existing technologies by providing a hole transport material for perovskite solar cells. This invention creatively employs a low-cost, high-stability o-phenanthroline metal complex as the hole transport material. Specifically, this o-phenanthroline metal complex possesses excellent semiconductor properties and good solubility in organic solvents, allowing for the fabrication of doped-free hole transport layers for perovskite solar cells using a low-cost liquid-phase spin-coating process. Furthermore, the halide ions in this metal complex can interact with incompletely coordinated Pb atoms on the surface of the light-absorbing layer. 2+ The ions form chemical interactions, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic methyl (-CH3) groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A hole transport material for perovskite solar cells, specifically a phenanthroline metal complex having the following structural formula:

[0010]

[0011] In the formula, M represents Cu. 2+ Zn 2+ Co 2+ Ni 2+ Fe 2+ Mn 2+ Pb 2+ Pt 2+ and Pd 2+ Divalent metal ions; X is F - Cl - ,Br - Or I - Halogen ions.

[0012] As an improvement to the hole transport material of the perovskite solar cell of the present invention, the preparation method of the o-phenanthroline metal complex includes the following steps: mixing 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline, a divalent metal halide, and an organic solvent to react and prepare the o-phenanthroline metal complex. The divalent metal halide is soluble in the organic solvent. The structural formula of the 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline is:

[0013]

[0014] The divalent metal halide is Cu. 2+ Zn 2+ Co2+ Ni 2+ Fe 2+ Mn 2+ Pb 2+ Pt 2+ or Pd 2+ Chlorides, bromides, or iodides of divalent metal ions.

[0015] As an improvement to the hole transport material of the perovskite solar cell of the present invention, the molar ratio of 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline and divalent metal halide is 1:1 to 3.

[0016] As an improvement to the hole transport material of the perovskite solar cell of the present invention, the organic solvent is at least one selected from dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide.

[0017] As an improvement to the hole transport material of the perovskite solar cell of the present invention, the reaction temperature is room temperature to 100°C and the reaction time is 2h to 48h.

[0018] Another objective of this invention is to provide 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 sequentially, wherein the material of the hole transport layer is the o-phenanthroline metal complex described in this invention.

[0019] As an improvement of the perovskite solar cell of the present invention, the substrate layer is made of indium tin oxide or fluorine-doped tin dioxide, and the thickness of the substrate layer is 5 nm to 20 nm; the electron transport layer is made of tin dioxide, and the thickness of the electron transport layer is 5 nm to 30 nm; the perovskite light-absorbing layer is made of CH3NH3PbI3.

[0020] The thickness of the perovskite light-absorbing layer is 100nm to 800nm; the thickness of the hole transport layer is 30nm to 100nm; the electrode layer is made of gold and has a thickness of 30nm to 150nm.

[0021] As an improvement of the perovskite solar cell of the present invention, the method for preparing the perovskite solar cell includes the following steps: forming an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and an electrode layer sequentially on a substrate layer, wherein the hole transport layer is prepared by a liquid phase spin coating method.

[0022] As an improvement to the perovskite solar cell of the present invention, the step of forming the electron transport layer includes: spin-coating an ethanol solution of stannous chloride onto the substrate layer, and then performing an annealing treatment to form the electron transport layer;

[0023] The step of forming the electrode layer includes: depositing gold on the side of the hole transport layer away from the substrate layer to form the electrode layer.

[0024] As an improvement to the perovskite solar cell of the present invention, the step of forming the perovskite light-absorbing layer includes: spin-coating a mixture of lead iodide, methyl ammonium iodide, dimethyl sulfoxide and dimethyl formamide on the side of the electron transport layer away from the substrate layer, and then performing an annealing treatment to form the perovskite light-absorbing layer;

[0025] In the mixture, the mass ratio of lead iodide, methyl ammonium iodide, dimethyl sulfoxide and dimethylformamide is (400-500):(100-200):(50-100):(500-800).

[0026] Compared to existing technologies, the beneficial technical effects of this invention are as follows: This invention is the first to creatively use the above-mentioned o-phenanthroline metal complex as a hole transport material in perovskite solar cells. Moreover, the o-phenanthroline metal complex in this invention has a novel structure and belongs to a completely new material. The o-phenanthroline metal complex in this invention contains a methyl group, and the methyl group is hydrophobic, which can effectively block the invasion of water molecules and protect the perovskite light-emitting layer.

[0027] In summary, the aforementioned o-phenanthroline metal complexes are inexpensive, possess excellent semiconductor properties, and exhibit good solubility in organic solvents. They can be used to prepare doped-free hole transport layers for perovskite solar cells using a low-cost liquid-phase spin-coating process. Furthermore, the halide ions in these metal complexes can interact with incompletely coordinated Pb atoms on the surface of the light-absorbing layer. 2+ The ions form chemical interactions, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic methyl (-CH3) groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the perovskite solar cell structure of the present invention.

[0029] Figure 2 This is an atomic force microscope (AFM) image of the hole transport layer in the perovskite solar cell obtained in Example 2.

[0030] Figure 3 The image shows the IV curve of the perovskite solar cell obtained in Example 2.

[0031] Figure 4 The curve showing the change in photoelectric conversion efficiency of the perovskite solar cell obtained in Example 2 over time in air;

[0032] Figure 5 The graph shows the change in photoelectric conversion efficiency of the perovskite solar cell obtained in Comparative Example 1 over time in air. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0035] To address the problems of high cost and poor stability caused by the introduction of dopants in traditional perovskite solar cells, one embodiment of the present invention provides an o-phenanthroline metal complex with the following structural formula:

[0036]

[0037] In the formula, M represents Cu. 2+ Zn 2+ Co 2+ Ni 2+ Fe 2+ Mn 2+ Pb 2+ Pt 2+ or Pd 2+ Divalent metal ions; X is F - Cl - ,Br - Or I - Halogen ions. The above-mentioned o-phenanthroline metal complex can be used as a hole transport material for doped perovskite solar cells. The halide ions in this metal complex can react with Pb that is not fully coordinated on the surface of the light-absorbing layer. 2+ The ions form chemical interactions, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic -CH3 groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the perovskite solar cell, and improve the device's lifespan and stability.

[0038] A method for preparing an o-phenanthroline metal complex according to one embodiment includes the following steps: mixing 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline, CuCl2, and an organic solvent to react and prepare the o-phenanthroline metal complex, wherein the CuCl2 is soluble in the organic solvent, and the structural formula of 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline is [insert structural formula here].

[0039]

[0040] The structural formula of the prepared o-phenanthroline metal complex is as follows:

[0041]

[0042] Specifically, the molar ratio of 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline to CuCl2 is 1:1 to 3. In one embodiment, the molar ratio of 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline to CuCl2 is 1:1, 1:2, and 1:3.

[0043] Preferably, the reaction temperature is between room temperature and 100°C, and the reaction time is between 2 hours and 48 hours. In one embodiment, room temperature refers to 10°C to 30°C. The reaction temperature is 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, or 80°C. The reaction time is 2 hours, 3 hours, 5 hours, 10 hours, 12 hours, 15 hours, 24 hours, 36 hours, or 48 hours.

[0044] Preferably, the organic solvent is dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran, dimethylformamide, or dimethyl sulfoxide.

[0045] Furthermore, after the reaction is complete, a purification step is included. Specifically, the purification step includes: filtering and washing the reaction product, followed by column chromatography separation, concentration, and recrystallization. In one embodiment, the aforementioned organic solvent is used for washing. The column chromatography separation process can be adjusted according to conventional methods in the art; for example, the eluent used can be a mixture of ethanol and dichloromethane. The reagent used in the recrystallization process can be a mixture of ethanol and dichloromethane. It is understood that only one commonly used processing parameter is listed above, and adjustments can be made according to actual conditions. The above steps enable further purification of the product.

[0046] The aforementioned o-phenanthroline metal complex is inexpensive, possesses excellent semiconductor properties, and exhibits good solubility in organic solvents. It can be used to prepare doped-free hole transport layers for perovskite solar cells using a low-cost liquid-phase spin-coating process. Furthermore, the halide ions in this metal complex can interact with incompletely coordinated Pb atoms on the surface of the light-absorbing layer. 2+The ions form chemical interactions, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic -CH3 groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device.

[0047] Please see Figure 1 The present invention also provides a perovskite solar cell 100, comprising a substrate layer 110, an electron transport layer 120, a perovskite light-absorbing layer 130, a hole transport layer 140, and an electrode layer 150 stacked together, wherein the hole transport layer 140 is made of the o-phenanthroline metal complex of the above embodiments or prepared by the o-phenanthroline metal complex preparation method of the above embodiments.

[0048] Specifically, the thickness of the substrate layer 110 is 5 nm to 20 nm. In one embodiment, the thickness of the substrate layer 110 is 5 nm, 10 nm, 15 nm, or 20 nm. The material of the substrate layer 110 is a transparent conductive material commonly used in perovskite solar cells 100 in the art, for example, the material of the substrate layer 110 is indium tin oxide (ITO) or fluorine-doped tin dioxide (FTO). Further, the material of the substrate layer 110 is FTO.

[0049] Specifically, the thickness of the electron transport layer 120 is 5 nm to 30 nm. In one embodiment, the thickness of the electron transport layer 120 is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm. The material of the electron transport layer 120 is tin dioxide. It is understood that the material of the electron transport layer 120 is not limited to tin dioxide, and can also be other materials commonly used in the art.

[0050] The perovskite light-absorbing layer 130 can be made of a perovskite light-absorbing material commonly used in perovskite solar cells 100, such as CH3NH3PbI3. Specifically, the thickness of the perovskite light-absorbing layer 130 is 100 nm to 800 nm. In one embodiment, the thickness of the perovskite light-absorbing layer 130 is 100 nm, 200 nm, 400 nm, 500 nm, 600 nm, or 800 nm.

[0051] The hole transport layer 140 has a thickness of 30 nm to 100 nm. In one embodiment, the hole transport layer 140 has a thickness of 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 100 nm.

[0052] The electrode layer 150 can be made of a commonly used electrode material in perovskite solar cells 100, such as gold. Specifically, the thickness of the electrode layer 150 is 30 nm to 150 nm. In one embodiment, the thickness of the electrode layer 150 is 40 nm, 60 nm, 80 nm, or 100 nm.

[0053] The hole transport layer 140 of the aforementioned perovskite solar cell 100 is made of a low-cost, high-performance semiconductor metal complex with good solubility, which is beneficial for the extraction and transport of photogenerated holes in the perovskite light-absorbing layer 130, helps to reduce the probability of electron-hole recombination, and is more conducive to improving the performance of the device. Furthermore, the halide ions in the phenanthroline metal complex molecule provided by this invention can react with the Pb that is not fully coordinated on the surface of the light-absorbing layer. 2+ The chemical interactions form, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic -CH3 groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device.

[0054] The present invention also provides a method for preparing a perovskite solar cell, comprising the following steps: sequentially forming an electron transport layer, a perovskite light-absorbing layer, a hole transport layer and an electrode layer on a substrate, wherein the material of the hole transport layer is the o-phenanthroline metal complex of the above embodiments or prepared by the preparation method of the o-phenanthroline metal complex of the above embodiments.

[0055] Specifically, a hole transport layer is prepared using a liquid-phase spin coating method. In one embodiment, the concentration of the spin coating solution used is 10 mg / ml, 20 mg / ml, 30 mg / ml, or 40 mg / ml; the solvent used is toluene, chlorobenzene, o-dichlorobenzene, o-xylene, or p-xylene; the spin coating speed is 800 rpm, 1000 rpm, 1200 rpm, or 1500 rpm; and the spin coating time is 40 s, 60 s, 90 s, or 120 s. The hole transport layer thickness obtained is 40–100 nm.

[0056] Specifically, the substrate material is FTO. Before the steps of sequentially forming the electron transport layer, perovskite light-absorbing layer, hole transport layer, and electrode layer on the substrate, a step of washing the substrate is included. Specifically, the etched substrate is ultrasonically treated sequentially in a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol for 15 minutes each, then removed, dried with nitrogen, placed in an oven, dried at 120°C for 8 hours, and treated with ultraviolet / ozone for 30 minutes to obtain the substrate layer. The above only lists one process parameter in the washing process, but it is not limited to this and can also use parameters commonly used in the art. Further, the thickness of the substrate layer is 5 nm to 20 nm.

[0057] The electron transport layer is made of tin dioxide. In one embodiment, the steps for forming the electron transport layer include: spin-coating an ethanol solution of stannous chloride onto a substrate, followed by annealing to form the tin dioxide electron transport layer. Specifically, in one embodiment, the concentration of the ethanol solution of stannous chloride is 0.1 mol / L. The spin-coating speed is 3000 rpm for 40 seconds. The annealing temperature is 180°C for 1 hour. It is understood that the above only lists one commonly used process parameter, but is not limited to it, and can be adjusted according to parameters such as the thickness of the electron transport layer to be formed. Specifically, the thickness of the electron transport layer is 5 nm to 30 nm.

[0058] The perovskite light-absorbing layer is made of CH3NH3PbI3. Specifically, the steps for forming the perovskite light-absorbing layer include: spin-coating a mixture of lead iodide, methyl ammonium iodide, dimethyl sulfoxide, and dimethylformamide onto the side of the tin dioxide electron transport layer away from the substrate, followed by annealing to obtain the perovskite light-absorbing layer. In one embodiment, the mass ratio of lead iodide, methyl ammonium iodide, dimethyl sulfoxide, and dimethylformamide in the mixture is (400–500):(100–200):(50–100):(500–800). For example, the mass ratio of lead iodide, methyl ammonium iodide, dimethyl sulfoxide, and dimethylformamide is 461:159:78:600. The spin-coating speed is 4000 rpm, and the time is 20 s. The annealing process includes annealing at 65°C for 2 min, followed by annealing at 100°C for 5 min. It is understood that the above only lists one commonly used process parameter, but it is not limited to this. It can also be adjusted according to parameters such as the thickness of the perovskite light-absorbing layer to be formed. Specifically, the thickness of the perovskite light-absorbing layer is 100nm to 800nm.

[0059] Furthermore, in the step of forming the perovskite light-absorbing layer, diethyl ether or chlorobenzene is added during spin coating to improve film quality. For example, 0.5 ml of diethyl ether or 0.3 ml of chlorobenzene is added.

[0060] The electrode layer is made of gold. The steps for forming the electrode layer include: depositing gold onto the side of the hole transport layer away from the FTO substrate to form the electrode layer. In one embodiment, the deposition rate is... For example, the evaporation rate is or The thickness of the electrode layer is 30nm to 150nm.

[0061] Furthermore, in one embodiment, the fabrication method of the above-mentioned perovskite solar cell specifically includes the following steps:

[0062] An ethanol solution of stannous chloride is spin-coated onto a substrate and then annealed to form an electron transport layer.

[0063] A mixture of lead iodide, methyl ammonium iodide, dimethyl sulfoxide and dimethyl formamide is spin-coated on the side of the electron transport layer away from the substrate, and then annealed to form a perovskite light-absorbing layer.

[0064] A hole transport layer is formed by liquid-phase spin-coating of an ortho-phenanthroline metal complex on the side of the perovskite light-absorbing layer away from the substrate.

[0065] Gold is deposited on the side of the hole transport layer away from the substrate to form an electrode layer, thus fabricating a perovskite solar cell.

[0066] The hole transport layer in the aforementioned perovskite solar cell facilitates the extraction and transport of photogenerated holes from the perovskite light-absorbing layer, helps reduce the electron-hole recombination probability, and further improves device performance. Furthermore, the halide ions in the o-phenanthroline metal complex molecule provided by this invention can react with the incompletely coordinated Pb on the surface of the light-absorbing layer. 2+ The chemical interactions form, which passivate the interface and effectively improve the device performance. In addition, the metal complex molecule contains hydrophobic -CH3 groups, which helps to resist the invasion of water molecules, effectively protect the light-emitting layer of the battery, and improve the lifespan and stability of the device.

[0067] Experiments have shown that the optimal photoelectric conversion efficiency parameters for the perovskite solar cell described above are: open-circuit voltage 1.05V and short-circuit current density 22.64mA / cm². 2 The fill factor is 68% and the conversion efficiency is 16.16%. After being stored in an atmospheric environment for 800 hours, the device still maintains more than 90% of its initial efficiency.

[0068] The following is a specific embodiment:

[0069] Example 1

[0070] This embodiment provides a hole transport material for perovskite solar cells. Specifically, the hole transport material is an o-phenanthroline metal complex, and its preparation process is as follows:

[0071] (1) Place CuCl2 (1.0 g, 7.4 mmol) and anhydrous ethanol (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CuCl2 is completely dissolved.

[0072] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of chloroform and transfer the resulting solution to the dropping funnel mentioned above.

[0073] (3) Heat the solution in the flask to 40°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 120 minutes, and then cool to room temperature.

[0074] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0075] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0076] (6) The product from step (5) above was further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment, with the following structural formula:

[0077]

[0078] Example 2

[0079] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0080] (1) Preparation of FTO substrate layer

[0081] 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 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained.

[0082] (2) Preparation of tin dioxide electron transport layer

[0083] 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.

[0084] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0085] In a nitrogen-rich environment, 461 mg of lead iodide (PbI2), 159 mg of methyl ammonium iodide (CH3NH3I), and 78 mg of dimethyl sulfoxide (DMSO) were dissolved in 600 mg of dimethylformamide (DMF) and 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.

[0086] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0087] 20 mg of the o-phenanthroline metal complex obtained in Example 1 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, the bottle was capped, and the glass bottle was placed in the water bath of a conventional ultrasonic cleaner and sonicated for 30 min. The bottle was then removed to obtain a 20 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of the chlorobenzene solution of the o-phenanthroline metal complex was transferred using a pipette and dropped onto the surface of the perovskite light-absorbing layer obtained in step (3). The layer was then spin-coated using a spin coater at 1000 rpm for 120 s. The substrate was placed on a heating stage and annealed at 100°C for 15 min to obtain an o-phenanthroline metal complex hole transport layer with a thickness of 50 nm.

[0088] (5) Fabrication of gold electrode layer

[0089] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 100 nm, thus obtaining the perovskite solar cell of this embodiment.

[0090] Comparative Example 1

[0091] The fabrication process of the perovskite solar cell in Comparative Example 1 is similar to that in Example 2, except that the material and fabrication process of the hole transport layer are different. In Comparative Example 1, spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene) was used as the material for the hole transport layer; the specific fabrication process of the spiro-OMeTAD hole transport layer is as follows:

[0092] In an N2 environment, a 100 mg / ml chlorobenzene solution of spiro-OMeTAD was prepared. 15.92 ml of 4-tert-butylpyridine and 9.68 ml of a 520 mg / ml lithium bis(trifluoromethanesulfonyl)imide acetonitrile solution were directly added to 0.3 ml of the above solution. The resulting solution was spin-coated onto a perovskite light-absorbing layer using a spin coater at 4000 rpm for 45 s, controlling the thickness of the spiro-OMeTAD hole transport layer to be 80 nm.

[0093] Example 3

[0094] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. The divalent metal halide used in this embodiment is ZnCl2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0095]

[0096] Specifically, the preparation process in this embodiment is as follows:

[0097] (1) Place ZnCl2 (7.4 mmol) and anhydrous methanol (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until ZnCl2 is completely dissolved.

[0098] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of ethanol and transfer the resulting solution to the dropping funnel mentioned above.

[0099] (3) Heat the solution in the flask to 50°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 150 minutes, and then cool to room temperature.

[0100] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0101] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0102] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0103] Example 4

[0104] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. In this embodiment, the divalent metal halide used is CoCl2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0105]

[0106] Specifically, the preparation process in this embodiment is as follows:

[0107] (1) Place CoCl2 (7.4 mmol) and anhydrous tetrahydrofuran (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CoCl2 is completely dissolved.

[0108] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of dimethylformamide and transfer the resulting solution to the dropping funnel mentioned above.

[0109] (3) Heat the solution in the flask to 60°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 250 minutes, and then cool to room temperature.

[0110] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0111] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0112] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0113] Example 5

[0114] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. In this embodiment, the divalent metal halide used is NiCl2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0115]

[0116] Specifically, the preparation process in this embodiment is as follows:

[0117] (1) Place NiCl2 (7.4 mmol) and anhydrous tetrahydrofuran (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CoCl2 is completely dissolved.

[0118] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of dimethyl sulfoxide and transfer the resulting solution to the dropping funnel mentioned above.

[0119] (3) Heat the solution in the flask to 70°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 350 minutes, and then cool to room temperature.

[0120] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0121] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0122] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0123] Example 6

[0124] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. In this embodiment, the divalent metal halide used is CuBr2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0125]

[0126] Specifically, the preparation process in this embodiment is as follows:

[0127] (1) Place CuBr2 (7.4 mmol) and dichloromethane (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CoCl2 is completely dissolved.

[0128] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of dichloromethane and transfer the resulting solution to the dropping funnel mentioned above.

[0129] (3) Heat the solution in the flask to 30°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 350 minutes, and then cool to room temperature.

[0130] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0131] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0132] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0133] Example 7

[0134] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. The divalent metal halide used in this embodiment is CuF2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0135]

[0136] Specifically, the preparation process in this embodiment is as follows:

[0137] (1) Place CuF2 (7.4 mmol) and chloroform (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CoCl2 is completely dissolved.

[0138] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of chloroform and transfer the resulting solution to the dropping funnel mentioned above.

[0139] (3) Heat the solution in the flask to 35°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 450 minutes, and then cool to room temperature.

[0140] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0141] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0142] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0143] Example 8

[0144] The preparation method of the o-phenanthroline metal complex in this embodiment is similar to that in Example 1, except that the divalent metal halide used is different. In this embodiment, the divalent metal halide used is PbI2. Other conditions are similar to those in Example 1. The structure of the o-phenanthroline metal complex obtained in this embodiment is as follows:

[0145]

[0146] Specifically, the preparation process in this embodiment is as follows:

[0147] (1) Place PbI2 (7.4 mmol) and ethanol (30 ml) in a 100 ml double-necked round-bottom flask, add a magnetic rotor, attach a dropping funnel and a condenser, and stir at room temperature until CoCl2 is completely dissolved.

[0148] (2) Dissolve 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline (2.9 g, 7.4 mmol) in 20 ml of ethanol and transfer the resulting solution to the dropping funnel mentioned above.

[0149] (3) Heat the solution in the flask to 35°C, stir the solution in the flask quickly, and slowly open the stopcock of the dropping funnel to allow the solution in the funnel to drip slowly into the flask at a rate of 2-3 drops per minute. After the solution in the funnel has been completely added to the flask, continue stirring for 450 minutes, and then cool to room temperature.

[0150] (4) The above reaction mixture was filtered through a short column packed with silica gel for column chromatography. The filtrate was collected and the organic solvent in the filtrate was evaporated to dryness using a rotary evaporator to obtain the crude product.

[0151] (5) The crude product was purified by column chromatography. The column was packed with SiO2 and a mixed solvent of ethanol / dichloromethane (volume ratio of 1 / 4) was used as the eluent. The product solution was collected and the solvent in the product solution was evaporated to dryness using a rotary evaporator.

[0152] (6) The product of step (5) above is further recrystallized in an ethanol / dichloromethane solvent system to obtain the o-phenanthroline metal complex of this embodiment.

[0153] Example 9

[0154] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0155] (1) Preparation of FTO substrate layer

[0156] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 10 nm.

[0157] (2) Preparation of tin dioxide electron transport layer

[0158] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 25 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 10 nm.

[0159] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0160] In a nitrogen-rich environment, 450 mg of lead iodide (PbI2), 170 mg of methyl ammonium iodide (CH3NH3I), and 65 mg of dimethyl sulfoxide (DMSO) were dissolved in 620 mg of dimethylformamide (DMF) and 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 15 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 500 nm.

[0161] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0162] 20 mg of the o-phenanthroline metal complex obtained in Example 3 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in a water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 10 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated using a spin coater at 800 rpm for 40 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 40 nm.

[0163] (5) Fabrication of gold electrode layer

[0164] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 80 nm, thus obtaining the perovskite solar cell of this embodiment.

[0165] Example 10

[0166] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0167] (1) Preparation of FTO substrate layer

[0168] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 8 nm.

[0169] (2) Preparation of tin dioxide electron transport layer

[0170] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 20 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 8 nm.

[0171] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0172] In a nitrogen-rich environment, 470 mg of lead iodide (PbI2), 130 mg of methyl ammonium iodide (CH3NH3I), and 75 mg of dimethyl sulfoxide (DMSO) were mixed and dissolved in 680 mg of dimethylformamide (DMF). The mixture was stirred at room temperature for 1 hour 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 13 seconds. 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 minutes and at 100 °C for 5 minutes to obtain a CH3NH3PbI3 perovskite light-absorbing layer with a thickness of 450 nm.

[0173] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0174] 20 mg of the o-phenanthroline metal complex obtained in Example 3 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 30 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1000 rpm for 60 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 60 nm.

[0175] (5) Fabrication of gold electrode layer

[0176] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 70 nm, thus obtaining the perovskite solar cell of this embodiment.

[0177] Example 11

[0178] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0179] (1) Preparation of FTO substrate layer

[0180] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 18 nm.

[0181] (2) Preparation of tin dioxide electron transport layer

[0182] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 50 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 18 nm.

[0183] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0184] In a nitrogen-rich environment, 420 mg of lead iodide (PbI2), 180 mg of methyl ammonium iodide (CH3NH3I), and 65 mg of dimethyl sulfoxide (DMSO) were dissolved in 610 mg of dimethylformamide (DMF) and 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 750 nm.

[0185] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0186] 20 mg of the o-phenanthroline metal complex obtained in Example 4 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 20 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1000 rpm for 40 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 35 nm.

[0187] (5) Fabrication of gold electrode layer

[0188] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 40 nm, thus obtaining the perovskite solar cell of this embodiment.

[0189] Example 12

[0190] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0191] (1) Preparation of FTO substrate layer

[0192] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 11 nm.

[0193] (2) Preparation of tin dioxide electron transport layer

[0194] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 70 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 22 nm.

[0195] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0196] In a nitrogen-rich environment, 488 mg of lead iodide (PbI2), 132 mg of methyl ammonium iodide (CH3NH3I), and 72 mg of dimethyl sulfoxide (DMSO) were dissolved in 710 mg of dimethylformamide (DMF) and 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 10 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 370 nm.

[0197] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0198] 20 mg of the o-phenanthroline metal complex obtained in Example 5 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 40 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated using a spin coater at 1500 rpm for 120 s. The substrate was then placed on a heating stage and annealed at 100 °C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 100 nm.

[0199] (5) Fabrication of gold electrode layer

[0200] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 120 nm, thus obtaining the perovskite solar cell of this embodiment.

[0201] Example 13

[0202] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0203] (1) Preparation of FTO substrate layer

[0204] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 11 nm.

[0205] (2) Preparation of tin dioxide electron transport layer

[0206] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 70 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 22 nm.

[0207] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0208] In a nitrogen-rich environment, 412 mg of lead iodide (PbI2), 111 mg of methyl ammonium iodide (CH3NH3I), and 28 mg of dimethyl sulfoxide (DMSO) were dissolved in 510 mg of dimethylformamide (DMF) and 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 15 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 270 nm.

[0209] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0210] 20 mg of the o-phenanthroline metal complex obtained in Example 6 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 30 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1200 rpm for 90 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 80 nm.

[0211] (5) Fabrication of gold electrode layer

[0212] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 130 nm, thus obtaining the perovskite solar cell of this embodiment.

[0213] Example 14

[0214] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0215] (1) Preparation of FTO substrate layer

[0216] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 14 nm.

[0217] (2) Preparation of tin dioxide electron transport layer

[0218] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 80 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 28 nm.

[0219] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0220] In a nitrogen-rich environment, 432 mg of lead iodide (PbI2), 141 mg of methyl ammonium iodide (CH3NH3I), and 48 mg of dimethyl sulfoxide (DMSO) were mixed and dissolved in 580 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 35 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 470 nm.

[0221] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0222] 20 mg of the o-phenanthroline metal complex obtained in Example 6 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 20 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1000 rpm for 80 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 85 nm.

[0223] (5) Fabrication of gold electrode layer

[0224] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 90 nm, thus obtaining the perovskite solar cell of this embodiment.

[0225] Example 15

[0226] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0227] (1) Preparation of FTO substrate layer

[0228] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 6 nm.

[0229] (2) Preparation of tin dioxide electron transport layer

[0230] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 45 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 12 nm.

[0231] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0232] In a nitrogen-rich environment, 432 mg of lead iodide (PbI2), 141 mg of methyl ammonium iodide (CH3NH3I), and 48 mg of dimethyl sulfoxide (DMSO) were mixed and dissolved in 580 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 30 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 370 nm.

[0233] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0234] 20 mg of the o-phenanthroline metal complex obtained in Example 7 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in a water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 10 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1200 rpm for 60 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 95 nm.

[0235] (5) Fabrication of gold electrode layer

[0236] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 70 nm, thus obtaining the perovskite solar cell of this embodiment.

[0237] Example 16

[0238] This embodiment provides a perovskite solar cell, the specific fabrication process of which is as follows:

[0239] (1) Preparation of FTO substrate layer

[0240] The etched transparent conductive substrate FTO was ultrasonically treated in cleaning agent, deionized water, anhydrous ethanol, acetone and isopropanol for 20 min in sequence. After being removed, it was dried with nitrogen (N2) and placed in an oven to dry at 120℃ for 8 h. After UV / ozone treatment for 30 min, the FTO substrate layer was obtained with a thickness of 9 nm.

[0241] (2) Preparation of tin dioxide electron transport layer

[0242] A 0.1 mol / L stannous chloride (SnCl2·2H2O) ethanol solution was prepared and spin-coated onto an FTO substrate at 3000 rpm for 80 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 17 nm.

[0243] (3) Preparation of CH3NH3PbI3 perovskite light-absorbing layer

[0244] In a nitrogen-rich environment, 432 mg of lead iodide (PbI2), 141 mg of methyl ammonium iodide (CH3NH3I), and 48 mg of dimethyl sulfoxide (DMSO) were mixed and dissolved in 580 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 35 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 470 nm.

[0245] (4) Preparation of o-phenanthroline metal complex hole transport layer

[0246] 20 mg of the o-phenanthroline metal complex obtained in Example 8 and 1 ml of chlorobenzene were placed in a 4 ml glass bottle, capped, and placed in the water bath of a conventional ultrasonic cleaner for 30 min. The bottle was then removed to obtain a 20 mg / ml chlorobenzene solution of the o-phenanthroline metal complex. 100 μL of this chlorobenzene solution was pipetted onto the surface of the perovskite light-absorbing layer obtained in step (3), and spin-coated at 1000 rpm for 40 s. The substrate was then placed on a heating stage and annealed at 100°C for 15 min to obtain the o-phenanthroline metal complex hole transport layer. The thickness of the hole transport layer was 45 nm.

[0247] (5) Fabrication of gold electrode layer

[0248] A gold electrode layer was prepared on the surface of the hole transport layer using a high-vacuum thermal evaporation method, at a depth of 1×10⁻⁶. -6 Under a vacuum of Pa, A gold electrode layer was prepared by high-rate evaporation deposition, and the thickness of the electrode layer was controlled to be 100 nm, thus obtaining the perovskite solar cell of this embodiment.

[0249] The following is the test section:

[0250] The effective area of ​​the perovskite solar cell devices in the above embodiments and comparative examples is 0.08 cm². 2 Test conditions: spectral distribution AM1.5G, illuminance 100mW / cm² 2 The AAA solar simulator (Beijing Zhuoli Hanguang Company) was used. The JV curve was measured using a Keithly 2400 digital source meter. All components were simply encapsulated with UV adhesive. The test was performed normally in an atmospheric environment.

[0251] Figure 2 This is an atomic force microscope (AFM) image of the hole transport layer in the perovskite solar cell obtained in Example 2. Figure 2 It can be seen that the hole transport layer of the o-phenanthroline metal complex has a regular and compact morphology.

[0252] Figure 3 This is the IV curve of the perovskite solar cell obtained in Example 2. (From...) Figure 3 The IV curve calculations show that the open-circuit voltage of the perovskite solar cell obtained in Example 2 is 1.05V, and the short-circuit current density is 22.64mA / cm². 2 The fill factor is 68%, and the conversion efficiency is 16.16%.

[0253] Figure 4 This is a curve showing the change in photoelectric conversion efficiency of the perovskite solar cell obtained in Example 2 over time in air. Figure 4 It can be seen that after the device is stored in an atmospheric environment for 800 hours, it still maintains more than 90% of its initial efficiency.

[0254] Perovskite solar cells prepared from the o-phenanthroline metal complexes obtained in Examples 3 to 8 all exhibited photoelectric conversion efficiencies greater than 16%, and maintained more than 90% of their initial efficiency after being stored in an atmospheric environment for 800 hours.

[0255] The perovskite solar cell obtained in Comparative Example 1 has an open-circuit voltage of 1.06V and a short-circuit current density of 22.57mA / cm². 2 The fill factor is 69%, and the conversion efficiency is 16.50%.

[0256] Figure 5 The graph shows the change in photoelectric conversion efficiency of the perovskite solar cell obtained in Comparative Example 1 over time in air. Figure 5 It can be seen that the device efficiency decays significantly in the atmospheric environment, and after 800 hours, the efficiency is only 46% of the initial efficiency.

[0257] The experimental data above show that using phenanthroline metal complexes as hole transport materials for perovskite solar cells is low-cost and can improve the device stability and lifespan of perovskite solar cells.

[0258] Based on the disclosure and teachings of the above specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the thickness and material of the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A hole transport material for perovskite solar cells, characterized in that, The hole transport material is specifically an o-phenanthroline metal complex, which has the following structural formula: ； In the formula, M represents Cu. 2+ Zn 2+ Co 2+ Ni 2+ and Pb 2+ At least one of them; X is F - Cl - ,Br - and I - At least one of them.

2. The method for preparing the hole transport material for perovskite solar cells according to claim 1, characterized in that, The process includes the following steps: reacting 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline, a divalent metal halide, and an organic solvent to prepare an o-phenanthroline metal complex, wherein the divalent metal halide is soluble in the organic solvent, and the structural formula of the 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline is as follows: 。 3. The method for preparing the hole transport material for perovskite solar cells according to claim 2, characterized in that: The molar ratio of 2,9-dimethyl-4,7-diphenylmethyl-1,10-phenanthroline to divalent metal halide is 1:1~3.

4. The method for preparing the hole transport material for perovskite solar cells according to claim 2, characterized in that: The organic solvent is at least one selected from dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide.

5. The method for preparing the hole transport material for perovskite solar cells according to claim 2, characterized in that: The reaction temperature is between room temperature and 100°C, and the reaction time is between 2 hours and 48 hours.

6. 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 sequentially stacked, characterized in that: The material of the hole transport layer is the o-phenanthroline metal complex as described in claim 1.

7. The perovskite solar cell according to claim 6, characterized in that: The substrate layer is made of indium tin oxide or fluorine-doped tin dioxide, and the thickness of the substrate layer is 5 nm to 20 nm; the electron transport layer is made of tin dioxide, and the thickness of the electron transport layer is 5 nm to 30 nm; the perovskite light-absorbing layer is made of CH3NH3PbI3. The thickness of the perovskite light-absorbing layer is 100nm~800nm; the thickness of the hole transport layer is 30nm~100nm; the electrode layer is made of gold and has a thickness of 30nm~150nm.

8. The perovskite solar cell according to claim 7, characterized in that, The method for fabricating the perovskite solar cell includes the following steps: sequentially forming an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and an electrode layer on a substrate, wherein the hole transport layer is prepared by a liquid-phase spin coating method.

9. The perovskite solar cell according to claim 8, characterized in that, The steps for forming the electron transport layer include: spin-coating an ethanol solution of stannous chloride onto the substrate layer, followed by annealing to form the electron transport layer; The step of forming the electrode layer includes: depositing gold on the side of the hole transport layer away from the substrate layer to form the electrode layer.

10. The perovskite solar cell according to claim 8, characterized in that, The steps for forming the perovskite light-absorbing layer include: spin-coating a mixture of lead iodide, methyl ammonium iodide, dimethyl sulfoxide and dimethylformamide on the side of the electron transport layer away from the substrate layer, and then performing an annealing treatment to form the perovskite light-absorbing layer; In the mixture, the mass ratio of lead iodide, methyl ammonium iodide, dimethyl sulfoxide and dimethylformamide is (400~500):(100~200):(50~100):(500~800).

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