Fullerene derivative, method for preparing the same, and use thereof

Abstract

The application discloses a fullerene derivative, a preparation method and application thereof, and belongs to the technical fields of fullerene materials and perovskite solar cells. The fullerene derivative and a mixture of the fullerene, monosubstituted fullerene derivative and disubstituted fullerene derivative in a reasonable proportion can be prepared through one-step synthesis. The fullerene derivative has good solubility and film-forming property, and an ordered and dense film can be formed through cross-linking initiated by a cross-linking agent. When the fullerene derivative is applied to a perovskite solar cell device, the photoelectric conversion efficiency and stability of the corresponding perovskite solar cell can be effectively improved. The fullerene electron transport layer film prepared by adjusting the proportion of the fullerene, monosubstituted fullerene derivative and disubstituted fullerene derivative can not only effectively improve the efficiency of the device, but also effectively save the production cost, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of fullerene materials and perovskite solar cell technology, specifically relating to a fullerene derivative, its preparation method, and its application in perovskite solar cells. Background Technology

[0002] In recent years, organic-inorganic hybrid halide perovskite solar cells have achieved efficiencies approaching those of traditional crystalline silicon solar cells due to their advantages such as high photoelectric conversion efficiency, low fabrication cost, and low-temperature fabrication capability. With ongoing research, the foundation for the initial commercial application of perovskite solar cells (PSCs) has been established. Inverse perovskite solar cells, with their excellent operational stability, low hysteresis, and low-temperature processing capability, have attracted significant attention in recent years and possess very promising market prospects.

[0003] Currently, the electron transport layers used in inverted perovskite solar cells are mainly fullerene materials, including C. 60 [6,6]phenyl-C 61 - Isomethyl butyrate (PCBM), etc. Among them, PCBM has become one of the most widely used electron transport layer materials due to its energy level being more compatible with conventional band gap (1.53~1.55eV) in inverted perovskite solar cells and its advantage of spin-coating. However, PCBM still has the following limitations: (1) PCBM has limited solubility in orthogonal solvents, resulting in the formation of a highly disordered and incompletely covered film on the perovskite layer, leading to energy loss. In addition, the pinholes in the electron transport layer (ETL) allow oxygen and water to permeate and can also serve as ion migration channels, causing device degradation; (2) Insufficient passivation ability. As a Lewis acid, PCBM can accept excess electrons from Pb-I antisite defects and deactivate the deep trap induced by aggregated halide ions; (3) Weak intermolecular interactions, disordered orientation, and weak adhesion to the perovskite surface lead to severe self-aggregation under continuous light or heating, which is detrimental to the morphological stability and long-term performance of PCBM. Therefore, developing fullerene materials with good film-forming properties, higher density, strong passivation ability, and long-term stability is currently the key to the development of trans-perovskite solar cells and urgently needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a fullerene derivative, its preparation method, and its application in perovskite solar cells. This material exhibits excellent solubility and film-forming properties, enhancing electron extraction and transport capabilities, thereby improving the photoelectric conversion efficiency of perovskite solar cells.

[0005] In addition, a mixture of fullerenes, monosubstituted fullerene derivatives and disubstituted fullerene derivatives in reasonable proportions can be obtained through a single synthesis. This mixture can be used as the electron transport layer of perovskite solar cells. The fullerene film in this mixture is dense and has good stability. Furthermore, it eliminates the need for separate purification steps for each material, thus saving production costs.

[0006] Another object of the present invention is to provide the application of the above-mentioned fullerene derivative electron transport material in the preparation of perovskite solar cells.

[0007] The third objective of this invention is to provide a method for preparing perovskite solar cells that is simple, has controllable parameters, and is suitable for large-scale industrial production.

[0008] The fourth objective of this invention is to provide a perovskite solar cell that uses a fullerene derivative electron transport material as an electron transport layer, thereby improving its photoelectric conversion efficiency.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention provides a fullerene derivative I and its preparation method.

[0011] Its chemical structural formula is:

[0012]

[0013] Where F is selected from C 60 C 70 Or C 84 C is preferred. 60 ; n = 1 to 6, preferably n = 1 or n = 2; R1 is selected from phenyl with at least one hydrogen atom substituted or unsubstituted by oxecyclopropane, oxecyclobutane, or oxecyclopentane, straight-chain or branched alkyl with 1 to 14 carbon atoms, or straight-chain or branched alkoxy with 1 to 14 carbon atoms; R2 is selected from phenyl with at least one hydrogen atom substituted by oxecyclopropane, oxecyclobutane, or oxecyclopentane, straight-chain or branched alkyl with 1 to 14 carbon atoms, or straight-chain or branched alkoxy with 1 to 14 carbon atoms.

[0014] Preferably, R1 is selected from: -CH3, -CH2CH3, -(CH2)2CH3, -(CH2)3CH3, -OCH3, -O(CH2) n CH3, -OCH(CH3)2, -O(CH2) n CH(CH3)2、

[0015]

[0016] Where n = 1 to 14;

[0017] Preferably, R2 is selected from

[0018]

[0019]

[0020] Where n = 1 to 14.

[0021] The preparation method of the above fullerene derivatives is as follows:

[0022] (1) Add the first catalyst, base, and corresponding alcohol to the reaction flask, then add the first solvent. After mixing thoroughly, slowly add the acyl chloride diluted with the first solvent at 0°C for 30–90 min, and then continue the reaction at room temperature for 9–24 h. After stopping the reaction, remove the solvent and perform column chromatography to obtain the intermediate.

[0023] (2) The intermediate is then added to a second solvent containing fullerene, and reacted at room temperature for 1 to 5 hours under the action of a second catalyst and a third catalyst. After removing the solvent, column chromatography is performed to obtain fullerene derivative I.

[0024] The above preparation method also has the following characteristic: the intermediate and C 60 The molar ratio is (0.6~2.4):1.

[0025] The above preparation method also has the following feature: the alkali is selected from one of triethylamine, sodium methoxide, sodium ethoxide, potassium tert-butoxide, or sodium tert-butoxide, preferably triethylamine.

[0026] The above preparation method also has the following feature: the first catalyst is selected from 4-dimethylaminopyridine (DMAP) and 4-pyrrolidinylpyridine (PPY), preferably PPY.

[0027] The above preparation method also has the following feature: the second catalyst is selected from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), triethylamine or NaH, preferably triethylamine.

[0028] The above preparation method also has the following characteristic: the third catalyst is selected from carbon tetrabromide or iodine.

[0029] The above preparation method also has the following feature: the first solvent is selected from one of dichloromethane, ethyl acetate, diethyl ether or toluene, preferably dichloromethane.

[0030] The above preparation method also has the following feature: the second solvent is selected from toluene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene or p-dichlorobenzene, preferably chlorobenzene.

[0031] It should be noted that those skilled in the art should be able to reasonably measure the solvent based on the above technical solution.

[0032] The present invention further provides the application of the fullerene derivative electron transport material in the preparation of perovskite solar cells.

[0033] This invention provides an inverted perovskite solar cell, comprising, in sequence, an ITO conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a buffer layer, and a metal electrode; wherein the electron transport layer is a fullerene derivative as described in the above technical solution.

[0034] The fabrication method of the above perovskite solar cells is as follows:

[0035] In this invention, there is no specific requirement for the ITO conductive substrate used in the fabrication of the inverted perovskite solar cell; any ITO conductive substrate well-known to those skilled in the art for fabricating solar cells can be used. This invention also preferably involves cleaning the ITO conductive substrate. The cleaning step includes: sequentially ultrasonically cleaning with deionized water, isopropanol, acetone, and ethanol, followed by ultraviolet ozone cleaning to obtain a pretreated ITO conductive substrate. In this invention, the ultrasonic cleaning time for each reagent is independently 10–30 min, preferably 20 min; the ultraviolet ozone cleaning time is 10–30 min, preferably 15 min.

[0036] The inverted perovskite solar cell of this invention includes a hole transport layer on an ITO substrate. In this invention, the hole transport layer is nano-nickel oxide (NiOx) and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz). The nano-nickel oxide is preferably an aqueous solution with a concentration of 10 mg / mL, and the spin-coating environment is air. The Me-4PACz is preferably an aqueous solution with a concentration of 0.2–1 mg / mL, more preferably 0.5 mg / mL, and the spin-coating environment is nitrogen (both water and oxygen content are less than 0.1 ppm). This invention does not specify a particular method for preparing the hole transport layer; any preparation method well-known to those skilled in the art can be used.

[0037] The perovskite active layer in this invention is a mixture of methylamine hydrobromide, methylamine hydrochloride, formamidinium hydroiodide, lead bromide, cesium iodide, and lead iodide, dissolved to obtain a perovskite active solution. This perovskite active solution is then spin-coated onto the surface of the hole transport layer to obtain the perovskite active layer. Preferably, the perovskite active solution is filtered before spin-coating. The filter screen pore size is preferably 0.10–0.45 μm, more preferably 0.22 μm.

[0038] The electron transport layer of the perovskite described in this invention is formed by spin-coating a fullerene derivative I dissolved in chlorobenzene. In this invention, the concentration of the sub-transport layer is preferably 10–30 mg / mL, more preferably 20 mg / mL.

[0039] The inverted perovskite solar cell of this invention includes a buffer layer on the surface of the electron transport layer. In this invention, the buffer layer is preferably tin oxide (ALD-SnO2) deposited by atomic layer deposition. In this invention, the ALD-SnO2 deposition thickness is preferably 10–25 nm, more preferably 20 nm.

[0040] The inverted perovskite solar cell of this invention includes an electrode on the surface of the buffer layer. In this invention, the electrode is preferably a silver electrode. In this invention, the thickness of the silver electrode is 80–100 nm, more preferably 95 nm. In this invention, the silver electrode is prepared by thermal evaporation deposition at a pressure of 5.5 × 10⁻⁶. -4 Pa.

[0041] The beneficial effects of this invention are as follows:

[0042] (1) The fullerene derivatives provided by the present invention have good solubility and film-forming properties, and good cross-linking effect. They can be used as electron transport layers in solar cell devices to improve the photoelectric conversion efficiency of the corresponding perovskite solar cells.

[0043] (2) The fullerene derivatives of the present invention can effectively suppress nonradiative recombination at the interface between the perovskite film and the electron transport layer and improve the stability of the perovskite solar cell through cross-linking.

[0044] (3) In addition, monosubstituted fullerene derivatives or a mixture of fullerenes, monosubstituted fullerene derivatives and disubstituted fullerene derivatives in a reasonable ratio can be obtained by one synthesis. When applied to the electron transport layer of perovskite solar cells, it can not only improve the efficiency of the device, but also save the separation and purification steps of each material and save production costs. Attached Figure Description

[0045] Figure 1 MALDI-TOF-MS image of F10;

[0046] Figure 2 This is a schematic diagram of an inverted perovskite solar cell structure.

[0047] Figure 3 JV curves of the inverted perovskite solar cells described in Examples 1-4 and Comparative Example 1;

[0048] Figure 4 For the application of the inverse perovskite solar cells described in Examples 1-4 and Comparative Example 1, V OC Statistical chart;

[0049] Figure 5 For the application of the inverse perovskite solar cells described in Examples 1-4 and Comparative Example 1, J SC Statistical chart;

[0050] Figure 6 FF statistics of the inverted perovskite solar cells described in Examples 1-4 and Comparative Example 1;

[0051] Figure 7 PCE statistics for the inverted perovskite solar cells described in Examples 1-4 and Comparative Example 1. Detailed Implementation

[0052] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0053] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0054] Example 1

[0055] The preparation route and method for a fullerene derivative F10 are as follows:

[0056]

[0057] Ethyl-2-ethoxyphosphate (2240.8 mg, 10.00 mmol) was dissolved in tetrahydrofuran (THF, 100 mL), and sodium hydride (401.7 mg, 10.00 mmol) was added at 0 °C. After reacting for 30 min, 3-methyloxetane-3-carboxaldehyde (compound a1, 500.3 mg, 5.00 mmol) was added, and the reaction was carried out at room temperature for 8 h. The mixture was purified by silica gel column chromatography to give ethyl 3-(3-methyloxetane-3-yl)prop-2-enoate (compound a2, 590.2 mg, 3.47 mmol), with a yield of 69%. Compound a2 (590.2 mg, 3.47 mmol) and palladium on carbon (409.1 mg, 3.47 mmol) were dissolved in tetrahydrofuran (100 mL), and the mixture was reacted in a hydrogen atmosphere for 16 h. Compound a3 (564.5 mg, 3.28 mmol) was obtained in 95% yield. Compound a3 (564.5 mg, 3.28 mmol) was dissolved in diethyl ether (50 mL), and lithium aluminum hydride (248.8 mg, 6.56 mmol) was added at 0 °C and reacted for 3 h. 3-Methyl-3-oxetanepropanol (compound a4, 307.0 mg, 2.36 mmol) was obtained in 72% yield.

[0058] 4-Pyrrolidinylpyridine (PPY, 17.8 mg, 0.12 mmol) was dissolved in dichloromethane (DCM, 50 mL), and triethylamine (TEA, 50.6 mg, 0.5 mmol) and 3-methyl-3-oxetanepropanol (compound a4, 307.0 mg, 2.36 mmol) were added and stirred thoroughly. Then, compound a5 (501.8 mg, 2.36 mmol) diluted with dichloromethane was slowly added under ice bath conditions. The reaction was carried out at room temperature for 16 h. After the reaction was completed, the mixture was purified by column chromatography to give compound a6 (685.8 mg, 2.24 mmol), with a yield of 53%. Compound a6 (168.4 mg, 0.55 mmol) was added to C6 dissolved in chlorobenzene (CB, 60 mL). 60 A mixed solution of CBr4 (400.0 mg, 0.55 mmol) and CBr4 (920.4 mg, 2.78 mmol) was added, and the mixture was stirred until homogeneous. Triethylamine (55.7 mg, 0.55 mmol) was then added as a catalyst. The reaction was carried out at room temperature for 5 h. After the reaction was complete, the product was purified by column chromatography to obtain the brown product F10 (358.4 mg, 0.35 mmol). The yield was 62%.

[0059] Example 2

[0060] Preparation of a mixture F10-1, the mixture comprising C 60 Monosubstituted fullerene derivative F10 and disubstituted fullerene derivative FB-10, and C 60The molar percentage of F10:FB-10 is 50%:40%:10%. The reaction route and preparation method are as follows:

[0061]

[0062] Take 168.4 mg (0.55 mmol) of a6 prepared in Example 1 and add it to C dissolved in chlorobenzene (CB, 60 mL). 60 A mixed solution of CBr4 (400.0 mg, 0.55 mmol) and CBr4 (920.4 mg, 2.8 mmol) was added, stirred until homogeneous, and then the catalyst triethylamine (TEA, 55.7 mg, 0.55 mmol) was added. The reaction was carried out at room temperature for 3 h. The mixture was purified by column chromatography to obtain unreacted CBr4. 60 (180.0 mg, 0.25 mmol), brown product F10 (204.8 mg, 0.20 mmol) and purple-red product FB-10 (66.4 mg, 0.05 mmol), C 60 The molar percentage of :F10:FB-10 is 50%:40%:10%. [The following appears to be a separate, unrelated sentence:] ... 60 A mixture of F10 and FB-10 is designated as F10-1, with a yield of 90.9%.

[0063] Example 3

[0064] Preparation of a mixture F10-2, the mixture comprising C 60 Monosubstituted fullerene derivative F10 and disubstituted fullerene derivative FB-10, and C 60 The molar percentage of F10:FB-10 is 20%:60%:20%. The preparation method is as follows:

[0065] Take 238.8 mg (0.78 mmol) of a6 prepared in Example 1 and add it to C dissolved in chlorobenzene (60 mL). 60 A mixed solution of CBr4 (400.0 mg, 0.55 mmol) and CBr4 (1288.6 mg, 3.9 mmol) was added, stirred until homogeneous, and then the catalyst triethylamine (78.9 mg, 0.78 mmol) was added. The reaction was carried out at room temperature for 5 h. The mixture was purified by column chromatography to obtain unreacted CBr4. 60 (70.0 mg, 0.10 mmol), brown product F10 (298.8 mg, 0.29 mmol) and purple-red product FB-10 (129.2 mg, 0.10 mmol), C 60 The molar percentage of :F10:FB-10 is 20%:60%:20%. [The following appears to be a separate, unrelated sentence:] ... 60 A mixture of F10 and FB-10 is designated as F10-2, with a yield of 88.4%.

[0066] Example 4

[0067] Preparation of a mixture F10-3, the mixture comprising C 60 Monosubstituted fullerene derivative F10 and disubstituted fullerene derivative FB-10, and C 60 The molar percentage of F10:FB-10 is 25%:50%:25%. The preparation method is as follows:

[0068] Take 238.8 mg (0.78 mmol) of a6 prepared in Example 1 and add it to C dissolved in chlorobenzene (60 mL). 60 A mixed solution of CBr4 (400.0 mg, 0.55 mmol) and CBr4 (1288.6 mg, 3.9 mmol) was added, stirred until homogeneous, and then the catalyst triethylamine (78.9 mg, 0.78 mmol) was added. The reaction was carried out at room temperature for 1.5 h. The mixture was purified by column chromatography to obtain unreacted CBr4. 60 (79.2 mg, 0.11 mmol), brown product F10 (235.5 mg, 0.23 mmol) and purple-red product FB-10 (146.1 mg, 0.11 mmol), C 60 The molar percentage of F10:FB-10 is 25%:50%:25%. [The following appears to be a separate, unrelated sentence:] ... 60 A mixture of F10 and FB-10 in the ratio of F10 to FB-10 is designated as F10-3, with a yield of 81.9%.

[0069] Application Example 1

[0070] The specific steps for fabricating an inverse perovskite solar cell with the structure ITO / nano nickel oxide / SAM / perovskite / F10 / ALD-SnO2 / Ag are as follows:

[0071] Cleaning the ITO substrate: The ITO substrate was ultrasonically cleaned with deionized water, isopropanol, acetone and ethanol for 20 min each, and then cleaned with ultraviolet ozone for 15 min to obtain the pretreated ITO substrate.

[0072] Spin-coating hole transport layer: Nano-nickel oxide was spin-coated onto a pretreated ITO substrate. After spin-coating, it was annealed at 150°C for 15 min to obtain a 50 nm thick nano-nickel oxide layer on the ITO substrate. The ITO / nano-nickel oxide layer substrate was then transferred to a nitrogen glove box, and Me-4PACz (SAM) was spin-coated onto the nano-nickel oxide layer. After spin-coating, it was annealed at 100°C for 10 min.

[0073] Preparation of the perovskite active layer: 670.2 mg lead iodide, 217.8 mg formamidine iodide, 28.2 mg lead bromide, 20.2 mg methylamine chloride, 19.5 mg cesium iodide, and 8 mg methylamine bromide were weighed and dissolved in a mixed polar solution of 800 μL LDMF and 200 μL LDMSO. The solution was stirred at 60 °C for 2 h to obtain a perovskite active liquid. The perovskite active liquid was filtered through a polytetrafluoroethylene filter with a pore size of 0.22 μm to obtain a perovskite spin-coating solution. 60 μL of the perovskite spin-coating solution was dropped onto the hole transport layer. After adding anhydrous anisole to the perovskite spin-coating solution, the spin-coated substrate was annealed at 100 °C for 30 min to obtain the perovskite active layer.

[0074] Preparation of electron transport layer: 20 mg of fullerene derivative F10 was weighed and dissolved in 1 mL of chlorobenzene and spin-coated onto the above perovskite active layer. The spin-coated substrate was annealed at 100 °C for 10 min to obtain an electron transport layer of about 30 nm on the perovskite active layer.

[0075] Preparation of the buffer layer: The substrate obtained above was transferred to the ALD system, and 20 nm of SnO2 was deposited while maintaining the substrate temperature at 100 °C.

[0076] Electrode fabrication: at 5.5 × 10 -4 Under Pa conditions, a 95 nm thick silver layer is thermally evaporated and deposited on the surface of the buffer layer as an electrode to obtain an inverted perovskite solar cell, denoted as F10. The structure of the inverted perovskite solar cell is as follows. Figure 4 As shown.

[0077] Application Example 2

[0078] An inverted perovskite solar cell with the structure ITO / nano nickel oxide / SAM / perovskite / F10-1 / ALD-SnO2 / Ag was prepared according to the preparation method described in Application Example 1. It is denoted as F10-1, except that the electron transport layer is a mixture of fullerene derivatives F10-1.

[0079] Application Example 3

[0080] An inverted perovskite solar cell with the structure ITO / nano nickel oxide / SAM / perovskite / F10-2 / ALD-SnO2 / Ag was prepared according to the preparation method described in Application Example 1. It is denoted as F10-2, except that the electron transport layer is a mixture of fullerene derivatives F10-2.

[0081] Application Example 4

[0082] An inverted perovskite solar cell with the structure ITO / nano nickel oxide / SAM / perovskite / F10-3 / ALD-SnO2 / Ag was prepared according to the preparation method described in Application Example 1. It is denoted as F10-3, except that the electron transport layer is a mixture of fullerene derivatives F10-3.

[0083] Comparative Example 1

[0084] An inverted perovskite solar cell with the structure ITO / nano nickel oxide / SAM / perovskite / PCBM / ALD-SnO2 / Ag was prepared according to the preparation method described in Application Example 1. It is denoted as PCBM, except that the electron transport layer is PCBM.

[0085] Test Example 1

[0086] The photoelectric conversion efficiency of the inverted perovskite solar cells described in Application Examples 1-4 and Comparative Example 1 was tested, and the results are shown in the figure below.

[0087] Figure 3 JV curves for inverted perovskite solar cells used in Examples 1-4 and Comparative Example 1; Figure 4 For the V of the inverted perovskite solar cells used in Examples 1-4 and Comparative Example 1 OC Statistical chart; Figure 5 J is used in the inverse perovskite solar cells of Examples 1-4 and Comparative Example 1. SC Statistical chart; Figure 6 FF statistics for inverted perovskite solar cells used in Examples 1-4 and Comparative Example 1; Figure 7 The PCE statistics are shown in Table 1 for the inverted perovskite solar cells used in Examples 1-4 and Comparative Example 1. The photoelectric performance parameters of each inverted perovskite solar cell in Examples 1-4 and Comparative Example 1 are shown in Table 1.

[0088] Table 1. Photoelectric performance parameters of the best devices for each type of inverted perovskite solar cell.

[0089]

[0090] from Figures 3-7 As shown in Table 1, when the fullerene derivative of Example 1 is used as the electron transport layer of an inverted perovskite solar cell, the open-circuit voltage, short-circuit current, fill factor, and efficiency of the device are superior to those of Comparative Example 1. This indicates that the fullerene derivative has a more ordered molecular arrangement, which promotes the transfer of charge from the perovskite active layer to the electron transport layer and reduces interfacial energy loss. Simultaneously, the ordered arrangement reduces the self-aggregation problem that fullerenes are prone to, enhances the passivation effect of the fullerene derivative functional groups on perovskite defects, reduces open-circuit voltage loss, increases the fill factor, and improves the photoelectric conversion efficiency of the inverted perovskite solar cell.

[0091] from Figures 4-5 As shown in Table 1, the mixed fullerene derivatives used in Examples 2-4 as the electron transport layer of inverted perovskite solar cells exhibit better open-circuit voltage and short-circuit current than those in Example 1. This indicates that among the mixed fullerene derivatives, the disubstituted fullerene derivatives have stronger interactions with the perovskite, better passivation of defects in the perovskite active layer, and lower interfacial open-circuit voltage loss. 60 Enhance the charge extraction capability of the electron transport layer.

[0092] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A fullerene derivative, characterized in that: The structural formula is as follows: ， Where F is fullerene C 60 C 70 C 84 Any one of the following; m = 1~6; R1 is , Any one of the following, where n = 1 to 14; R2 is , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Any one of the following, where n = 1 to 14.

2. A method for preparing the fullerene derivative as described in claim 1, characterized in that: Includes the following steps: (1) Mix the first catalyst, base and alcohol, add the first solvent, mix well, slowly add the acyl chloride diluted with the first solvent at 0 °C, react for 30-90 min, continue the reaction at room temperature for 9-24 h, remove the solvent and then column chromatography to obtain the intermediate. ; (2) The intermediate was added to a second solvent containing fullerene, and the reaction was carried out at room temperature for 1-5 hours under the action of a second catalyst and a third catalyst. After removing the solvent, column chromatography was performed to obtain the fullerene derivative. The first catalyst is 4-dimethylaminopyridine or 4-pyrrolidinylpyridine; the first solvent is one of dichloromethane, ethyl acetate, diethyl ether, and toluene; The second catalyst is one of 1,8-diazabicyclo[5.4.0]undec-7-ene, triethylamine, and NaH; The third catalyst is carbon tetrabromide or iodine.

3. The method according to claim 2, characterized in that: The molar ratio of the intermediate to the fullerene is (0.6~2.4):

1.

4. The method according to claim 2, characterized in that: In step (1), the alkali is one of triethylamine, sodium methoxide, sodium ethoxide, potassium tert-butoxide, and sodium tert-butoxide.

5. The method according to claim 2, characterized in that: In step (2), the second solvent is one of toluene, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, and p-dichlorobenzene.

6. A fullerene derivative as described in claim 1 or a fullerene derivative prepared by the method of any one of claims 2 to 5, applied to the electron transport layer of an inverse lead-based perovskite solar cell.

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