A perovskite solar cell with a modified layer of polyphenolic organic compounds and a preparation method thereof

Abstract

The present invention relates to a perovskite solar cell with a polyphenolic organic compound modification layer. Its cross-sectional structure sequentially includes a transparent conductive substrate, an electron transport layer, a perovskite active layer, a polyphenolic organic compound modification layer, a hole transport layer, and a metal counter electrode from bottom to top. The polyphenolic organic compound is one or more of gallic acid, epigallocatechin gallate, and tannic acid. The present invention also discloses a preparation method of a perovskite solar cell with a polyphenolic organic compound modification layer. By introducing a polyphenolic organic compound passivation layer between the perovskite active layer and the hole transport layer, the non-radiative recombination of carriers at the interface is inhibited, thereby improving the efficiency of the device. At the same time, due to the excellent antioxidant properties of the polyphenolic organic compound, the oxidation reaction of the perovskite can be effectively inhibited, thereby improving the stability of the perovskite solar cell.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite solar cells, and particularly to a perovskite solar cell with a polyphenolic organic compound modification layer and a preparation method thereof. Background Art

[0002] Solar cell technology is an important direction in energy chemistry research, and photovoltaic power generation is the main technical path to achieve the goal of carbon neutrality. Although the global photovoltaic power generation has increased rapidly in the past decade, its proportion in the total power generation is still very small, and there is still huge room for growth. In order to achieve low-cost photovoltaic power generation, it is necessary to continue to develop solar cell technologies that are expected to achieve low cost and high efficiency. Perovskite solar cells are solar cells that use organic-inorganic hybrid metal halide semiconductors as light-absorbing materials, with a cubic octahedral structure of the ABX3 type, as Figure 1 shown. It has the advantages of strong photon absorption ability, wide spectral absorption range, long carrier lifetime, and bipolar transport, and has strong application potential in cross fields such as optoelectronic devices.

[0003] Perovskite solar cells have the advantages of adjustable bandgap, simple preparation process, high defect tolerance, high manufacturing yield, and easy processing. They can not only be used to prepare large-area battery modules, but also be used as top cells to stack with crystalline silicon cells to achieve higher industrialization efficiency and further reduce the cost of photovoltaic power generation. In order to achieve commercial mass production of perovskite solar cells, there are still many key problems to be solved. Among them, the defects in perovskite materials will lead to non-radiative recombination of carriers, thus affecting the efficiency of the battery. At the same time, the stability of perovskite solar cells is also a stumbling block to their commercialization. Based on the above problems, there is an urgent need for an efficient and stable perovskite solar cell and its preparation method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a perovskite solar cell with a polyphenolic organic compound modification layer and a preparation method thereof, aiming at the problems of many defects in existing perovskite solar cells and easy oxidation reactions under light, moisture, and oxygen, resulting in a decrease in their efficiency and stability. By introducing a polyphenolic organic compound passivation layer between the perovskite active layer and the hole transport layer, the non-radiative recombination of carriers at the interface is inhibited, thereby improving the efficiency of the device; at the same time, due to the excellent antioxidant properties of polyphenolic organic compounds, the oxidation reaction of perovskite can be effectively inhibited, thereby improving the stability of perovskite solar cells.

[0005] The object of the present invention can be achieved by the following solutions:

[0006] The present invention provides a perovskite solar cell with a modified layer of polyphenolic organic compounds. The solar cell includes a transparent conductive substrate, an electron transport layer, a perovskite active layer, a modified layer of polyphenolic organic compounds, a hole transport layer, and a metal counter electrode. The outermost layers of the perovskite solar cell are the transparent conductive substrate and the metal counter electrode respectively. The modified layer of polyphenolic organic compounds is coated on the surface of the perovskite active layer, and the other side of the modified layer of polyphenolic organic compounds is the electron transport layer or the hole transport layer. The polyphenolic organic compounds include one or more of gallic acid, epigallocatechin gallate, and tannic acid.

[0007] For the perovskite solar cell with a modified layer of polyphenolic organic compounds, the solar cell sequentially includes from bottom to top:

[0008] a transparent conductive substrate, an electron transport layer, a perovskite active layer, a modified layer of polyphenolic organic compounds, a hole transport layer, and a metal counter electrode;

[0009] or a transparent conductive substrate, an electron transport layer, a modified layer of polyphenolic organic compounds, a perovskite active layer, a hole transport layer, and a metal counter electrode;

[0010] or a transparent conductive substrate, a hole transport layer, a modified layer of polyphenolic organic compounds, a perovskite active layer, an electron transport layer, and a metal counter electrode;

[0011] or a transparent conductive substrate, a hole transport layer, a perovskite active layer, a modified layer of polyphenolic organic compounds, an electron transport layer, and a metal counter electrode.

[0012] For the perovskite solar cell of the present invention, its cross-sectional structure can sequentially include from bottom to top a transparent conductive substrate, an electron transport layer, a perovskite active layer, a modified layer of polyphenolic organic compounds, a hole transport layer, and a metal counter electrode. A modified layer of polyphenolic organic compounds is provided between the perovskite active layer and the hole transport layer. This modified layer of polyphenolic organic compounds can also be between the electron transport layer and the perovskite active layer. In the perovskite cell structure, the electron transport layer and the hole transport layer can be interchanged. In the present invention, this modified layer is coated on the perovskite active layer, and it is acceptable whether the layer above the modified layer is the electron transport layer or the hole transport layer. In the present invention, only the hole transport layer above the modified layer is mentioned, which can be extended to the electron transport layer above the modified layer.

[0013] As an embodiment of the present invention, the transparent conductive substrate is one or more combinations of FTO, ITO, IZO, and AZO.

[0014] As an embodiment of the present invention, the electron transport layer is one of TiO2, SnO2, ZnO, and PCBM; the thickness of the electron transport layer is 20 - 120 nm.

[0015] As an embodiment of the present invention, the perovskite active layer is one of organic-inorganic hybrid perovskite or all-inorganic perovskite; the thickness of the perovskite active layer is 400 - 600 nm.

[0016] As an embodiment of the present invention, the thickness of the polyphenolic organic compound modification layer is 1 - 100 nm.

[0017] As an embodiment of the present invention, the preparation method of the polyphenolic organic compound modification layer is specifically: coating an isopropanol solution containing polyphenolic organic compound on the perovskite active layer, and performing annealing treatment to obtain the polyphenolic organic compound modification layer.

[0018] As an embodiment of the present invention, the hole transport layer is one or a combination of Spiro-OMeTAD, NiOx, PTAA, PEDOT:PPS materials, and the thickness is 400 - 600 nm.

[0019] The present invention also provides a preparation method of a perovskite solar cell with a polyphenolic organic compound modification layer, and the preparation method includes the following steps:

[0020] S1. Prepare an electron transport layer on the substrate of the transparent conductive substrate to obtain the electron transport layer;

[0021] S2. Coat the perovskite precursor solution on the electron transport layer to form a perovskite thin film layer, and perform annealing treatment on the thin film layer to obtain the perovskite active layer;

[0022] S3. Coat a solution containing polyphenolic organic compound on the perovskite active layer, and perform annealing treatment to obtain the polyphenolic organic compound modification layer; the solvent of the polyphenolic organic compound includes one or several of isopropanol, toluene, chlorobenzene, chloroform.

[0023] S4. Prepare a hole transport layer on the substrate where the polyphenolic organic compound modification layer is prepared;

[0024] S5. Evaporate a metal electrode on the hole transport layer as the metal counter electrode, and thus obtain the perovskite solar cell with the polyphenolic organic compound modification layer.

[0025] As an embodiment of the present invention, in step S1, the preparation method of the electron transport layer is specifically: spin-coating the electron transport layer solution on the substrate, and then performing annealing treatment. The temperature of the annealing treatment is 120 - 180 °C, and the time is 10 - 30 minutes.

[0026] As an embodiment of the present invention, in steps S2 and S3, the coating method is any one of spin coating, blade coating, slot-die continuous coating, spraying, printing.

[0027] As an embodiment of the present invention, in step S2, the perovskite precursor solution is one of an organic-inorganic hybrid perovskite solution or an all-inorganic perovskite solution. The perovskite precursor solution includes reactants AX and metal halide BX2, where A is at least any one of cesium, amino group, amidinium group or alkali group, B is a divalent metal cation, including any one of lead, tin, cadmium, indium, copper, gallium cations, and X is at least any one of iodine, bromine, chlorine, thiocyanate, acetate anions. The solvent used is at least any one of amide solvents, sulfone solvents, sulfoxide solvents, ester solvents, alcohol solvents, ether solvents, and the concentration of the perovskite precursor solution is 0.5 - 1.5 mol / L. The preparation method of the perovskite active layer is to coat the perovskite solution on the electron transport layer by any one of spin coating, blade coating, slot die coating, spraying or printing, and anneal the thin film layer to obtain the perovskite active layer.

[0028] As an embodiment of the present invention, in step S2, the annealing temperature is 100 - 210 °C and the time is 5 - 30 minutes.

[0029] As an embodiment of the present invention, in step S3, the concentration of the isopropanol solution containing polyphenol organic compound is 0.1 - 1 mg / mL.

[0030] As an embodiment of the present invention, in step S3, the annealing temperature is 100 - 120 °C and the time is 5 - 10 minutes.

[0031] As an embodiment of the present invention, in step S4, the preparation method of the hole transport layer is specifically: spin coat the hole transport layer solution onto the polyphenol organic compound modified layer. Among them, the solvent of the Spiro-OMeTAD hole transport layer solution is chlorobenzene, and each 1 mL of chlorobenzene contains 60 - 120 mg of Spiro-OMeTAD powder material, 20 - 100 μL of lithium bis(trifluoromethanesulfonyl)imide, and 30 - 50 μL of 4-tert-butylpyridine.

[0032] Conventional hydrophobic electrode modification layers can only protect and increase the water resistance of perovskite. The hydroxyl functional groups in the polyphenol organic compounds in the present invention interact with ions or atoms in the perovskite, passivate the defects existing in the perovskite, and inhibit the non-radiative recombination of carriers, thereby improving the efficiency of the device; at the same time, due to the excellent antioxidant properties of polyphenol organic compounds, they can effectively inhibit the oxidation reaction of perovskite under light, moisture, and oxygen, thereby effectively improving the stability of perovskite solar cells.

[0033] Since the polyphenolic organic compound in the present invention is coated on the perovskite active layer, too high annealing temperature will cause damage to the perovskite active layer, reducing its efficiency and stability. Too low annealing temperature will cause the hydroxyl functional groups in the polyphenolic organic compound to fail to effectively interact with the ions or atoms in the perovskite, thus affecting its function of passivating the defects in the perovskite active layer. Too long annealing time will cause degradation of the perovskite active layer, damaging its internal structure, and increasing energy consumption at the same time. Too short annealing time will also cause the hydroxyl functional groups in the phenolic organic compound to fail to effectively interact with the ions or atoms in the perovskite, thus affecting its function of passivating the defects in the perovskite active layer.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The perovskite solar cell with a polyphenolic organic compound modification layer and its preparation method according to the present invention introduce a polyphenolic organic compound passivation layer between the perovskite active layer and the hole transport layer, suppressing the non-radiative recombination of carriers at the interface, thereby improving the efficiency of the device. At the same time, due to the excellent antioxidant property of the polyphenolic organic compound, it can effectively inhibit the oxidation reaction of the perovskite, thus improving the stability of the perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects and advantages of the present invention will become more apparent:

[0037] Figure 1 It is a schematic diagram of the molecular structure in the perovskite active layer;

[0038] Figure 2 It is the chemical structure diagram of gallic acid;

[0039] Figure 3 It is the chemical structure diagram of epigallocatechin gallate;

[0040] Figure 4 It is the chemical structure diagram of tannic acid;

[0041] Figure 5 It is the schematic cross-sectional structure diagram of the perovskite solar cell of the present invention;

[0042] Figure 6 It is the J-V curve diagram of the perovskite solar cell of Example 1 of the present invention;

[0043] Figure 7 It is the stability test diagram of the perovskite solar cell of Example 1 of the present invention working for 1000 hours;

[0044] Figure 8J-V curve diagram of the perovskite solar cell of Comparative Example 1 of the present invention;

[0045] Figure 9 Stability test diagram of the perovskite solar cell of Comparative Example 1 of the present invention working for 1000 hours;

[0046] Figure 10 J-V curve diagram of the perovskite solar cell of Comparative Example 2 of the present invention;

[0047] Figure 11 J-V curve diagram of the perovskite solar cell of Comparative Example 4 of the present invention;

[0048] Figure 12 J-V curve diagram of the perovskite solar cell of Comparative Example 5 of the present invention. Specific embodiments

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following examples are implemented on the premise of the technical solution of the present invention, providing detailed implementation manners and specific operation processes, which will help those skilled in the art to further understand the present invention. It should be noted that the protection scope of the present invention is not limited to the following embodiments. Several adjustments and improvements made under the premise of the concept of the present invention all belong to the protection scope of the present invention.

[0050] The present invention discloses a perovskite solar cell with a polyphenolic organic compound modification layer. Its cross-sectional structure includes, from bottom to top in sequence, a transparent conductive substrate, an electron transport layer, a perovskite active layer, a polyphenolic organic compound modification layer, a hole transport layer, and a metal counter electrode. A layer of polyphenolic organic compound modification layer is provided between the perovskite active layer and the hole transport layer; the polyphenolic organic compound is one or more of gallic acid, epigallocatechin gallate, or tannic acid. The principle is that the hydroxyl functional groups in the polyphenolic organic compound interact with ions or atoms in the perovskite, passivate the defects existing in the perovskite, and inhibit the non-radiative recombination of carriers, thereby improving the efficiency of the device; at the same time, due to the excellent antioxidant properties of the polyphenolic organic compound, it can effectively inhibit the oxidation reaction of the perovskite under light, moisture, and oxygen, thereby effectively improving the stability of the perovskite solar cell.

[0051] The present invention also discloses a preparation method of a perovskite solar cell with a polyphenolic organic compound modification layer as described above, including the following steps:

[0052] S1. Prepare an electron transport layer on the substrate of the transparent conductive substrate;

[0053] S2. Coating a perovskite precursor solution on a substrate deposited with an electron transport layer by any one of spin coating, blade coating, slot-die continuous coating, spraying or printing to form a perovskite thin film layer, and annealing the thin film layer to obtain a perovskite active layer;

[0054] S3. Coating an isopropanol solution containing a polyphenol organic compound on the substrate of the perovskite active layer by any one of spin coating, blade coating, slot-die continuous coating, spraying or printing, and annealing the modified layer to obtain a polyphenol organic compound modified layer;

[0055] S4. Preparing a hole transport layer on the substrate on which the polyphenol organic compound modified layer is prepared;

[0056] S5. Evaporating a metal electrode on the substrate on which the hole transport layer is prepared as a metal counter electrode, thereby completing the preparation process of the perovskite solar cell with a polyphenol organic compound modified layer;

[0057] Among them, in step S1, the transparent conductive substrate is one or a combination of FTO, ITO, IZO, and AZO materials; the electron transport layer is one of TiO2, SnO2, ZnO, and PCBM, and the thickness is 20 - 120 nm.

[0058] Among them, in step S2, the perovskite active layer is one of organic-inorganic hybrid perovskite or all-inorganic perovskite, and the thickness is 400 - 600 nm.

[0059] Among them, in step S3, the isopropanol solution containing a polyphenol organic compound has a concentration of 0.1 - 1 mg / mL, an annealing temperature of 100 - 120 °C, and an annealing time of 5 - 10 minutes.

[0060] Among them, in step S4, the hole transport layer is one or a combination of Spiro-OMeTAD, NiOx, PTAA, and PEDOT:PPS materials, and the thickness is 400 - 600 nm.

[0061] The following combines specific examples to illustrate a preparation method of a perovskite solar cell with a polyphenol organic compound modified layer according to the present invention.

[0062] Example 1

[0063] A preparation method of a perovskite solar cell, including the following steps:

[0064] (1) Sequentially cleaning a 2X2 cm FTO glass plate with acetone, isopropanol, and deionized water by ultrasonic cleaning for 30 minutes each, then drying it with nitrogen, and treating it with ultraviolet ozone for 20 minutes;

[0065] (2) Spin-coat 50 - 90 μL of an aqueous SnO₂ solution with a mass fraction of 2.67% on the treated FTO substrate at a spin-coating speed of 3000 rpm for 30 s, and anneal at 180 °C for 30 minutes. The thickness of the prepared SnO₂ electron transport layer is 20 - 30 nm.

[0066] (3) Dissolve 1.5 mmol of PbI₂, 1.5 mmol of FAI, and 0.225 mmol of MACl in 1 mL of a solvent (the volume ratio of DMF:DMSO is 4:1), mix and stir to obtain a perovskite precursor solution. Take 60 μL of the above precursor solution and spin-coat it on the substrate in step (2) at 5000 rpm for 20 s, and simultaneously drop 600 μL of chlorobenzene anti-solvent, and anneal at 150 °C for 20 minutes to prepare a perovskite active layer with a thickness of 500 - 600 nm.

[0067] (4) Dissolve gallic acid in isopropanol at a concentration of 0.5 mg / mL, spin-coat it at 3000 rpm for 30 s, and finally anneal at 100 °C for 5 minutes to obtain a polyphenolic organic compound modification layer; Figure 2 is the chemical structure diagram of gallic acid.

[0068] (5) Spin-coat the pre-prepared Spiro-OMeTAD hole transport layer solution onto the polyphenolic organic compound modification layer at 3000 rpm for 30 s; then deposit a 70 nm Au electrode on the device by thermal evaporation to complete the preparation of the entire solar cell.

[0069] The internal structure of the perovskite solar cell prepared in this embodiment is as Figure 5 shown.

[0070] Example 2

[0071] A method for preparing a perovskite solar cell, comprising the following steps:

[0072] The method of this embodiment is the same as that of Example 1, except that in step (4), epigallocatechin gallate is dissolved in isopropanol at a concentration of 0.5 mg / mL, spin-coated at 3000 rpm for 30 s, and finally annealed at 100 °C for 5 minutes to obtain a polyphenolic organic compound modification layer; Figure 3 is the chemical structure diagram of epigallocatechin gallate.

[0073] Example 3

[0074] A method for preparing a perovskite solar cell, comprising the following steps:

[0075] The method of this embodiment is the same as that of Embodiment 1, except that in step (4), tannic acid is dissolved in isopropanol at a concentration of 0.5 mg / mL, spin-coated at 3000 rpm for 30 s, and finally annealed at 100 °C for 5 minutes to obtain a polyphenolic organic compound modification layer; Figure 4 is the chemical structure diagram of tannic acid.

[0076] Attached Figure 6 and 7 are the test data tables of perovskite solar cells with a polyphenolic organic compound modification layer prepared by the preparation method of Embodiment 1 of the present invention. It can be seen from Attached Figure 6 that the perovskite solar cell with a polyphenolic organic compound modification layer has excellent photoelectric conversion performance, and the efficiency reaches 24.1%. It can be seen from Attached Figure 7 that the perovskite solar cell with a polyphenolic organic compound modification layer has excellent long-term stability, and the efficiency decline of the cell after operating under light for 1000 hours is less than 10%.

[0077] Comparative Example 1

[0078] A preparation method of a perovskite solar cell includes the following steps:

[0079] The method of this comparative example is the same as that of Embodiment 1, except that step (4) is not included.

[0080] Attached Figure 8 and 9 are the test data tables of perovskite solar cells without a polyphenolic organic compound modification layer prepared by the preparation method of Comparative Example 1. It can be seen from Attached Figure 8 that, compared with Attached Figure 6 of Embodiment 1, the perovskite solar cell without a polyphenolic organic compound modification layer shows poor photoelectric conversion performance, and the efficiency is only 22.1%. It can be seen from Attached Figure 9 that, compared with Attached Figure 7 of Embodiment 1, the perovskite solar cell without a polyphenolic organic compound modification layer shows poor long-term stability, and the efficiency of the cell has dropped below 50% of the initial efficiency after operating under light for 600 hours.

[0081] Comparative Example 2

[0082] A preparation method of a perovskite solar cell includes the following steps:

[0083] The method of this comparative example is the same as that of Embodiment 1, except that in step (4), gallic acid is replaced by 2-naphthalenethiol.

[0084] Attached Figure 10 is the test data table of the perovskite solar cell prepared by the preparation method of Comparative Example 2. It can be seen from Attached Figure 10It can be seen that, compared with the attachment of Example 1 Figure 6 the perovskite solar cell with the 2-naphthalenethiol modification layer in Patent 2 shows poor optoelectronic conversion performance, with an efficiency of 23.2%.

[0085] Comparative Example 3

[0086] A preparation method of a perovskite solar cell includes the following steps:

[0087] The method of this comparative example is the same as that of Example 1, except that the annealing temperature in step (4) is 200 °C. An excessively high annealing temperature in step 4 will cause the degradation of the perovskite active layer, damage the perovskite structure, and make the corresponding perovskite solar cell almost inefficient.

[0088] Comparative Example 4

[0089] A preparation method of a perovskite solar cell includes the following steps:

[0090] The method of this comparative example is the same as that of Example 1, except that the annealing temperature in step (4) is 80 °C.

[0091] attachment Figure 11 is the test data table of the perovskite solar cell prepared by the preparation method of Comparative Example 4. It can be seen from the attachment Figure 11 that, compared with the attachment of Example 1 Figure 6 the excessively low annealing temperature in step (4) will cause the hydroxyl functional groups in the polyphenolic organic compound to not effectively interact with the ions or atoms in the perovskite, thus affecting its function of passivating the defects in the perovskite active layer, resulting in a decrease in the optoelectronic conversion performance of the perovskite battery, and the efficiency is only 22.9%.

[0092] Comparative Example 5

[0093] A preparation method of a perovskite solar cell includes the following steps:

[0094] The method of this comparative example is the same as that of Example 1, except that the annealing time in step (4) is 3 minutes.

[0095] attachment Figure 12 is the test data table of the perovskite solar cell prepared by the preparation method of Comparative Example 5. It can be seen from the attachment Figure 12 that, compared with the attachment of Example 1 Figure 6 the excessively short annealing time in step (4) will also cause the hydroxyl functional groups in the phenolic organic compound to not effectively interact with the ions or atoms in the perovskite, thus affecting its function of passivating the defects in the perovskite active layer, resulting in a decrease in the optoelectronic conversion performance of the perovskite battery, and the efficiency is only 23.1%.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A perovskite solar cell having a polyphenol organic compound modified layer, characterized in that: The solar cell comprises a transparent conductive substrate, an electron transport layer, a perovskite active layer, a polyphenol organic compound modified layer, a hole transport layer and a metal counter electrode; the outermost layers of the perovskite solar cell are the transparent conductive substrate and the metal counter electrode, the polyphenol organic compound modified layer is coated on the surface of the perovskite active layer, and the other side of the polyphenol organic compound modified layer is the hole transport layer; The polyphenol organic compound includes one or more of gallic acid, epigallocatechin gallate, and tannic acid.

2. The perovskite solar cell according to claim 1, characterized in that The transparent conductive substrate is one or more combinations of FTO, ITO, IZO, and AZO.

3. The perovskite solar cell according to claim 1, wherein The electron transport layer is one of TiO2, SnO2, ZnO, and PCBM; and the thickness of the electron transport layer is 20-120 nm.

4. The perovskite solar cell according to claim 1, wherein The perovskite active layer is an organic-inorganic hybrid perovskite or an all-inorganic perovskite; the thickness of the perovskite active layer is 400-600 nm.

5. The perovskite solar cell according to claim 1, wherein The thickness of the polyphenol organic compound modified layer is 1-100 nm.

6. The perovskite solar cell according to claim 1, characterized in that The method for preparing the polyphenol organic compound modified layer is specifically as follows: applying an isopropyl alcohol solution containing the polyphenol organic compound on the perovskite active layer, and performing annealing treatment to obtain the polyphenol organic compound modified layer.

7. The perovskite solar cell according to claim 1, wherein The hole transport layer is Spiro-OMeTAD, NiO x , PTAA, PEDOT:PPS materials or one or more combinations thereof, with a thickness of 400-600nm.

8. A method for preparing a perovskite solar cell having a polyphenol organic compound modified layer, characterized in that: The preparation method comprises the following steps: S1. preparing an electron transport layer on a transparent conductive substrate to obtain an electron transport layer; S2, coating the perovskite precursor solution on the electron transport layer to form a perovskite thin film layer, and annealing the thin film layer to obtain a perovskite active layer; S3, coating a solution containing a polyphenol organic compound on the perovskite active layer, and performing an annealing treatment to obtain a polyphenol organic compound modified layer; the polyphenol organic compound includes one or more of gallic acid, epigallocatechin gallate, and tannic acid; the solvent for the polyphenol organic compound includes one or more of isopropyl alcohol, toluene, chlorobenzene, and chloroform; S4, preparing a hole transport layer on the substrate on which the polyphenol organic compound modified layer is prepared; S5. Vapor-depositing a metal electrode on the hole transport layer as a metal counter electrode to obtain the perovskite solar cell with the polyphenol organic compound modified layer.

9. The method for preparing a perovskite solar cell according to claim 8, wherein: In step S3, the concentration of the isopropanol solution containing polyphenolic organic compounds is 0.1-1 mg / mL; the annealing temperature is 100-120° C., and the annealing time is 5-10 minutes.

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