Fullerene derivative, preparation method thereof and solar cell

Abstract

The invention relates to the technical field of solar cells, in particular to a fullerene derivative, a preparation method thereof and a solar cell. The fullerene derivative comprises a fullerene part, BCP and a derivative part thereof, and the fullerene part, the BCP and the derivative part thereof are bonded through chemical bonds. The fullerene derivative can be used for preparing an electron transport layer or a modification layer between the electron transport layer and a perovskite layer, and the photoelectric conversion efficiency and stability of a formed cell can be improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more specifically, to fullerene derivatives, their preparation methods, and solar cells. Background Technology

[0002] Solar cells mainly include inorganic solar cells, dye-sensitized solar cells, organic solar cells, and perovskite solar cells. Among them, perovskite solar cells have attracted researchers' attention due to their excellent photoelectric conversion efficiency, thus sparking a research boom in perovskite solar cells. Typically, a perovskite single-junction solar cell consists of a conductive glass substrate, an electron transport layer, a perovskite layer, a hole transport layer, and metal electrodes. The electron transport layer's role is to promote electron transport and prevent electron recombination; therefore, it directly affects the photoelectric conversion efficiency, i.e., the performance of the perovskite solar cell. However, in existing technologies, the interface between the perovskite and the electron transport layer contains numerous defects, forming non-radiative recombination centers, which reduces the photoelectric conversion efficiency of the perovskite cell.

[0003] To address the aforementioned issues, existing technologies have conducted extensive research on interface engineering and electron transport layer materials (such as fullerenes) and have achieved certain results. However, there is still significant room for improvement in the photoelectric conversion efficiency of perovskite solar cells.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide fullerene derivatives, their preparation methods, and solar cells. Embodiments of this invention provide a novel fullerene derivative that can be used as an electron transport layer or a modification layer between an electron transport layer and a perovskite layer, thereby improving the photoelectric conversion efficiency and stability of the formed solar cell.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a fullerene derivative comprising a fullerene moiety and a BCP and its derivative moiety, wherein the fullerene moiety and the BCP and its derivative moiety are chemically bonded together.

[0008] In an optional embodiment, the BCP and its derivatives are partially derived from any of the compounds shown in the following structural formulas:

[0009] The fullerene is derived from C20-C100 fullerenes.

[0010] In an optional embodiment, the chemical bonding is achieved by the fullerene moiety and the BCP and its derivative moiety through a dipole cycloaddition of an aldehyde group.

[0011] In an optional embodiment, the fullerene derivative is selected from compounds with the following structural formulas:

[0012] R1 and R2 are each independently selected from C1-C5 alkyl groups.

[0013] In an optional embodiment, R1 and R2 are each independently selected from C1-C3 alkyl groups, with methyl being the most preferred.

[0014] In an optional embodiment, the fullerene derivative is selected from compounds with the following structural formulas:

[0015]

[0016] In a second aspect, the present invention provides a method for preparing the fullerene derivative described in the foregoing embodiments, comprising: reacting a fullerene raw material for forming a fullerene moiety and a raw material for forming a BCP and its derivative moiety to form a fullerene moiety and a BCP and its derivative moiety, wherein the two are chemically bonded.

[0017] In an optional embodiment, the method includes: mixing the fullerene raw material, the raw material forming the BCP and its derivative portions, and sarcosine and its derivatives to carry out a Prato reaction;

[0018] The molar ratio of the raw material forming BCP and its derivatives to the fullerene raw material is 1:(1-10);

[0019] The molar ratio of the raw material forming BCP and its derivatives to the sarcosine and its derivatives is 1:(1-1.5);

[0020] The reaction temperature is 100-190℃, and the reaction time is 12-20 hours.

[0021] In a sixth aspect, the present invention provides a solar cell comprising a functional layer formed of a fullerene derivative as described in the foregoing embodiments;

[0022] Preferably, the solar cell is a perovskite single-cell cell or a perovskite tandem cell;

[0023] The functional layer is an electron transport layer or a modification layer, wherein the modification layer is located between the electron transport layer and the perovskite layer.

[0024] The present invention has the following beneficial effects: In the embodiments of the present invention, fullerenes are chemically bonded to BCP and its derivatives, thereby modifying the fullerenes. The fullerene derivatives can be prepared as a modification layer between the electron transport layer and the perovskite layer. In this case, it can effectively passivate defects in the perovskite film, while blocking hole migration, reducing charge accumulation at the active layer interface, improving electron collection capability at the interface, increasing carrier mobility, and reducing carrier recombination, thereby improving the conversion efficiency and stability of the perovskite solar cell device. Simultaneously, the fullerene derivatives have the potential to be used as an electron transport layer. In summary, the fullerene derivatives provided by the embodiments of the present invention can achieve "dual uses," exerting multiple effects and improving the performance of perovskite solar cells from multiple aspects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell provided in Application Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the perovskite solar cell provided in Application Example 2 of the present invention;

[0028] Figure 3 The J / V curve of the perovskite solar cell provided in Application Example 1 of the present invention;

[0029] Figure 4 The J / V curve of the perovskite solar cell provided in Application Example 2 of the present invention;

[0030] Figure 5 The J / V curve is shown in Comparative Example 1 of this invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0032] This invention provides a fullerene derivative comprising a fullerene moiety and a BCP and its derivative moiety, wherein the fullerene moiety and the BCP and its derivative moiety are chemically bonded. This fullerene derivative can interact with perovskite, thereby passivating defects in the perovskite film and acting as a hole blocker; subsequently, it can serve as a modification layer between the perovskite layer and the electron transport layer, or as an electron transport layer.

[0033] The fullerene portion is derived from fullerene raw materials, which include, but are not limited to, C20-C100 fullerenes, such as any one of C20, C60, C70, C76, and C80. Preferably, the fullerene raw material is C60.

[0034] BCP and its derivatives are partially derived from any of the compounds shown in the following structural formulas:

[0035]

[0036] Preferred

[0037]

[0038] Using the above compounds can further ensure the performance of batteries formed using fullerene derivatives.

[0039] Aldehyde-containing BCP and its derivatives react with fullerene raw materials to form a fullerene moiety and the BCP and its derivative moiety, which are then bonded together. Specifically, the two are chemically bonded through a dipole cycloaddition of the aldehyde group.

[0040] Furthermore, the fullerene derivatives are selected from compounds with the following structural formulas: Wherein, R1 and R2 are each independently selected from C1-C5 alkyl groups; for example, methyl, ethyl, n-propyl, n-butyl, and n-pentyl C1-C5 alkyl groups, preferably C1-C3 alkyl groups, and most preferably methyl; for example,

[0041] The fullerene derivatives provided in this invention have excellent solubility and can be completely dissolved in solvents such as chloroform, toluene, and chlorobenzene, with chlorobenzene being preferred. Subsequently, when spin-coating to prepare the functional layer of the corresponding battery, layer separation can be reduced and photothermal tolerance can be improved.

[0042] In a second aspect, the present invention provides a method for preparing the fullerene derivative described in the foregoing embodiments, comprising: reacting a fullerene raw material for forming a fullerene moiety and a raw material for forming a BCP and its derivative moiety to form a fullerene moiety and a BCP and its derivative moiety, wherein the two are chemically bonded.

[0043] Specifically, fullerene raw materials, raw materials for forming BCP and its derivatives, and sarcosine and its derivatives are mixed and subjected to a Prato reaction.

[0044] The amino acid is selected from sarcosine and its derivatives; the molar ratio of the raw material forming the BCP and its derivative moiety to the fullerene raw material is 1:(1-10); for example, any value between 1:(1-10) or any range between two values, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, and 1:10. The molar ratio of the raw material forming the BCP and its derivative moiety to the amino acid is 1:(1-1.5); for example, any value between 1:(1-1.5) or any range between two values, such as 1:1, 1:1.2, and 1:1.5. The reaction temperature is 100-190℃, for example, any value between 100℃ and 190℃ or any range between two values, such as 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, and 190℃. The reaction time is 12-20 hours; for example, any value between 12-20 hours or any range between any two values, such as 12 hours, 15 hours, 17 hours, and 20 hours.

[0045] The above reaction conditions ensure the smooth progress of the Prattor reaction and are conducive to the formation of fullerene derivatives.

[0046] It should be noted that the fullerene raw materials and the raw materials used to form BCP and its derivatives can be purchased directly or synthesized independently. Independent synthesis can also be carried out by referring to existing literature or materials.

[0047] Thirdly, the present invention provides a solar cell comprising a functional layer formed from a fullerene derivative as described in the foregoing embodiments; wherein the solar cell is a perovskite single-cell cell or a perovskite tandem cell; the functional layer is an electron transport layer or a modification layer, wherein when the functional layer is a modification layer, the modification layer is located between the electron transport layer and the perovskite layer.

[0048] Specifically, the fullerene derivatives provided in this embodiment of the invention, while retaining the excellent electron extraction capability of fullerenes, introduce BCP and its derivatives, thereby exhibiting good wettability on the perovskite surface. This allows for the formation of a thin, smooth fullerene film layer, the modification layer mentioned in this embodiment, which blocks hole migration, reduces charge accumulation at the active layer interface, improves electron collection capability at the interface, increases carrier mobility, reduces carrier recombination, and thus improves the conversion efficiency and stability of the perovskite solar cell device. Simultaneously, this dense modification layer can improve the interface defects and contact between the perovskite film and C60. This modification layer further facilitates the interaction between perovskite and fullerenes, resulting in tighter contact between layers and further enhancing the performance of the perovskite solar cell.

[0049] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0050] Example 1

[0051] This invention provides a fullerene derivative with the following structural formula:

[0052]

[0053] This embodiment also provides a method for preparing the above-mentioned fullerene derivative, including:

[0054] S1, Synthetic compound 2;

[0055] Compound 2 was synthesized according to the following synthetic route:

[0056] Specifically, under N2 protection, trimethyl orthoacetate (210 mL, 1.85 mol) and Michaelis-Menten acid (8.7 g, 58.97 mmol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and thermometer. The mixture was refluxed at 100 °C for 15 min, then cooled to 40 °C and o-phenylenediamine (3 g, 27.78 mmol) was added. The mixture was then heated to 100 °C and refluxed for 2 h. Finally, the mixture was allowed to cool to room temperature and reacted overnight. After the reaction was complete, a solid precipitate was present. The precipitate was filtered, washed with diethyl ether, and dried under vacuum to obtain a white solid powder product, 5,5'-((1,2-phenylenebis(azonidyl))bis(ethane-1-yl-1-ylidene))di(2,2-dimethyl-1,3-dioxane-4,6-dione), 7.2 g, with a yield of 58.54%.

[0057] The characterization data are as follows: H 1-NMR (400MHz, Chloroform-d) δ12.83(s,2H),7.51(dd,J=5.9,3.5Hz,2H),7.36(ddd,J=26.0,5.8,3.6Hz,2H),2.54(s,6H),1.72(s,12H).

[0058] S2, Synthetic compound 3;

[0059] Compound 3 was synthesized according to the following synthetic route:

[0060] Specifically, under N2 protection, compound 2 (4.1 g, 9.23 mmol) and diphenyl ether (105 mL) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a thermometer. The mixture was heated to 240 °C and refluxed for 40 min. After the reaction was completed, the mixture was cooled to room temperature, and a brown solid precipitated. The solid was filtered, and the filter cake was washed with acetone, n-hexane, and diethyl ether. The filter cake was then vacuum dried to obtain 1.6 g of the brown solid powder product 2,9-dimethyl-1,10-dihydro-1,10-phenanthroline-4,7-dione, with a yield of 72.19%.

[0061] Characterization data: H 1 -NMR (400MHz, Methanol-d4) δ8.06(s,2H),6.56(s,2H),2.64(s,6H).

[0062] S3, Synthetic compound 4;

[0063] Compound 4 was synthesized according to the following synthetic route:

[0064] Specifically, under N2 protection, compound 3 (1.5 g, 6.25 mmol) and phosphorus tribromooxy (30 g, 104.64 mmol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a thermometer. The temperature was raised to 80 °C, and the reaction was allowed to proceed for 6 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was quenched in an ice-water mixture. The pH was adjusted to 14 with a saturated sodium hydroxide aqueous solution. The mixture was filtered, washed with water, and finally dried under vacuum to obtain 900 mg of the brown solid powder product 4,7-dibromo-2,9-dimethyl-1,10-phenanthroline, with a yield of 39.56%.

[0065] Characterization data: H 1 -NMR(400MHz,Chloroform-d)δ8.26(s,2H),7.64(s,2H),2.93(s,6H).

[0066] S4, Synthetic compound 5;

[0067] Compound 5 was synthesized according to the following synthetic route:

[0068] Specifically: Under N2 protection, compound 4 (908.1 mg, 2.49 mmol), p-aldehyde phenylboronic acid (780 mg, 5.2 mmol), potassium carbonate (1.03 g, 7.47 mmol), tetrakis(triphenylphosphine)palladium (143.79 mg, 0.05 mmol), dioxane (20 mL), and water (2 mL) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and thermometer. The reaction was carried out at 90 °C under nitrogen protection for 16 h. The reaction solution was cooled to room temperature, the dissolved components were removed by rotary evaporation, dissolved in ethyl acetate, washed with water, and back-extracted three times with water. The organic phase was dried over anhydrous sodium sulfate, and the crude product was purified by column chromatography to obtain 450 mg of the yellow solid product 4,4'-(2,9-dimethyl-1,10-phenanthroline-4,7-diyl)dibenzaldehyde, with a yield of 43.77%.

[0069] Characterization data: H 1 -NMR (400MHz, DMSO-d6) δ10.14(s,2H),8.11(d,J=7.9Hz,4H),7.81(d,J=7.9Hz,4H),7.68(d,J=12.9Hz,4H),2.88(s,6H).

[0070] It should be noted that compound 5 provided in this embodiment was prepared in-house, but it can also be purchased directly.

[0071] S5. Synthetic fullerene derivatives;

[0072] Fullerene derivatives were synthesized according to the following synthetic route;

[0073] Specifically, under N2 protection, compound 5 (50 mg, 0.12 mmol), C60 (429 mg, 0.5958 mmol), and sarcosine (14 mg, 0.1573 mmol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and thermometer. The mixture was dissolved in 10 mL of DCB and reacted at 110 °C for 16 h. After the reaction was complete, the mixture was cooled to room temperature and purified by column chromatography. C60 was first recovered with toluene, followed by elution with eluents of DCM:MeOH = 100:1 and 50:1. 33 mg of the target product was obtained.

[0074] Characterization data: MALDI-TOF-MS: m / z calcd for C92H30N4 1190.2, found 1191.2 [M+H] + .

[0075] Example 2

[0076] This embodiment provides a method for preparing a fullerene derivative, which is the same as the method in Example 1, except that the only difference is in step S5, where the molar ratio of BCP to fullerene is 1:1.2. Specifically, under N2 protection, compound 5 (150.7 mg, 0.3623 mmol), C60 (312.7 mg, 0.4343 mmol), and sarcosine (41.96 mg, 0.47 mmol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a thermometer, dissolved in DCB (15 mL), and reacted at 110 °C for 16 h. After the reaction was completed, the mixture was cooled to room temperature and purified by column chromatography. C60 was first recovered with toluene, and then eluted with eluents of DCM:MeOH = 100:1 and 50:1. 95 mg of the target product was obtained.

[0077] The MALDI-TOF-MS results showed that the product structure was consistent with that of the product in Example 1.

[0078] Example 3

[0079] This embodiment provides a method for preparing a fullerene derivative, which is the same as the method in Example 1, except that the only difference is in step S5, where the molar ratio of BCP to fullerene is 1:

[0080] 9.7. Specifically, under N2 protection, compound 5 (124 mg, 0.2981 mmol), C60 (2.08 g, 2.8889 mmol), and sarcosine (27.89 mg, 0.313 mmol) were added to a three-necked round-bottom flask equipped with a magnetic stirrer and a thermometer. The flask was dissolved in DCB (15 mL) and reacted at 110 °C for 16 h. After the reaction was complete, the mixture was cooled to room temperature and purified by column chromatography. C60 was first recovered with toluene, followed by elution with eluents of DCM:MeOH = 100:1 and 50:1. 102 mg of the target product was obtained.

[0081] The MALDI-TOF-MS results showed that the product structure was consistent with that of the product in Example 1.

[0082] Application Example 1

[0083] This embodiment provides a perovskite single-cell solar cell, which includes an electron transport layer formed from the fullerene derivative (hereinafter referred to as 1537) of Example 1. The structure of this perovskite solar cell is shown below. Figure 1 Specifically: ITO glass / hole transport layer / Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 )3 / 1537 / BCP / Cu.

[0084] This embodiment provides a method for preparing a perovskite solar cell:

[0085] 1) Substrate preparation: The etched ITO substrate is ultrasonically cleaned with detergent, deionized water, acetone and isopropanol for 15 minutes in sequence, dried in a nitrogen atmosphere, and then treated with ultraviolet ozone for 30 minutes to remove organic impurities from the surface of the ITO substrate.

[0086] 2) Hole transport layer preparation: A hole transport layer was prepared by spin-coating a chlorobenzene solution of PTAA (4 mg / mL) onto an ITO substrate at 5000 rpm for 30 seconds and then annealing at 100°C for 10 minutes.

[0087] 3) Perovskite layer preparation: 1.4 M Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 A perovskite layer was prepared by spin-coating a DMF:DMSO (4:1) precursor solution of 3 onto a hole transport layer at 3000 rpm for 25 s. The perovskite film was then treated by a vacuum method and annealed at 100 °C for 10 min to obtain the perovskite layer.

[0088] 4) Electron transport layer preparation: Fullerene derivatives were dissolved in chlorobenzene solution (concentration 14 mg / mL), and the solution was spin-coated onto the above perovskite thin film photosensitive layer at 3000 rpm, maintained for 30 seconds, and annealed at 100°C for 5 minutes to obtain an electron transport layer based on fullerene derivatives. Subsequently, 5 nm of BCP was deposited at a rate of 0.1 Å / s.

[0089] 5) Electrode preparation: In a vacuum chamber at 5 × 10⁻⁶... 4 A 100 nm thick copper electrode was deposited under high vacuum conditions.

[0090] Application Example 2

[0091] This embodiment provides a perovskite solar cell, which includes a modification layer formed from the fullerene derivative of Example 1. This modification layer is located between the perovskite layer and the electron transport layer. The structure of the perovskite solar cell is as follows: Figure 2 As shown.

[0092] The fabrication method of this perovskite solar cell is as follows:

[0093] 1) Substrate preparation: The etched ITO substrate is ultrasonically cleaned with detergent, deionized water, acetone and isopropanol for 15 minutes in sequence, dried in a nitrogen atmosphere, and then treated with ultraviolet ozone for 30 minutes to remove organic impurities from the surface of the ITO substrate.

[0094] 2) Hole transport layer preparation: A hole transport layer was prepared by spin-coating a chlorobenzene solution of PTAA (4 mg / mL) onto an ITO substrate at 5000 rpm for 30 seconds and annealing at 100°C for 10 minutes.

[0095] 3) Perovskite layer preparation: 1.4 M Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 A perovskite layer was prepared by spin-coating a DMF:DMSO (4:1) precursor solution of 3 onto a hole transport layer at 3000 rpm for 25 s. The perovskite film was then treated by a vacuum method and annealed at 100 °C for 10 min to obtain the perovskite layer.

[0096] 4) Preparation of the modified layer: The fullerene derivative was dissolved in chlorobenzene solution (concentration 1 mg / mL), and the solution was spin-coated onto the above perovskite film photosensitive layer at 3000 rpm. After maintaining the solution for 30 seconds, it was annealed at 100°C for 5 minutes to obtain an intermediate modified layer based on the fullerene derivative and fullerene.

[0097] 5) Electron transport layer preparation: A 20 nm thick fullerene C60 layer was deposited as the electron transport layer by thermal evaporation at a rate of 0.1 Å / s. Subsequently, a 5 nm thick BCP was deposited at a rate of 0.1 Å / s.

[0098] 6) Electrode preparation: In a vacuum chamber at 5 × 10⁻⁶... 4 A 100 nm thick copper electrode was deposited under high vacuum conditions.

[0099] Comparative Example 1

[0100] This comparative example provides a perovskite solar cell comprising an electron transport layer formed of fullerene C60. The structure of this perovskite solar cell is as follows: ITO glass / hole transport layer / Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 )3 / C60 / BCP / Cu.

[0101] The specific preparation method of this perovskite solar cell is as follows:

[0102] 1) Substrate preparation: The etched ITO substrate is ultrasonically cleaned with detergent, deionized water, acetone and isopropanol for 15 minutes in sequence, dried in a nitrogen atmosphere, and then treated with ultraviolet ozone for 30 minutes to remove organic impurities from the surface of the ITO substrate.

[0103] 2) Hole transport layer preparation: A hole transport layer was prepared by spin-coating a chlorobenzene solution of PTAA (4 mg / mL) onto an ITO substrate at 5000 rpm for 30 seconds and annealing at 100°C for 10 minutes.

[0104] 3) Perovskite layer preparation: 1.4 M Cs 0.22 FA 0.78 Pb(I 0.865 Br 0.135 A perovskite layer was prepared by spin-coating a DMF:DMSO (4:1) precursor solution of 3 onto a hole transport layer at 3000 rpm for 25 s. The perovskite film was then treated by a vacuum method and annealed at 100 °C for 10 min to obtain the perovskite layer.

[0105] 4) Electron transport layer preparation: A 20 nm thick fullerene C60 layer was deposited as the electron transport layer by thermal evaporation at a rate of 0.1 Å / s. Subsequently, a 5 nm thick BCP was deposited at a rate of 0.1 Å / s.

[0106] 5) Electrode preparation: In a vacuum chamber at 5 × 10⁻⁶... 4 A 100 nm thick copper electrode was deposited under high vacuum conditions.

[0107] The perovskite solar cell device in the above application examples and comparative examples has an area of ​​0.085 cm². 2 This is determined by the area of ​​the test mask. A xenon lamp solar simulator was used, with a test light source intensity of AM 1.5G and 100mW / cm². 2 The photoelectric properties of the fabricated battery device were tested to obtain the open-circuit voltage, current density, conversion efficiency, and fill factor of the perovskite battery.

[0108] See results Figures 3-5 and the following Table 1, in which Figure 3 The J / V curve of the perovskite solar cell in Application Example 1 is shown. Figure 4 The J / V curve of the perovskite solar cell in Application Example 2 is shown. Figure 5 The J / V curve is for the perovskite solar cell in Comparative Example 1.

[0109] Table 1

[0110]

[0111]

[0112] According to Table 2 above and Figures 3-5It can be seen that the perovskite solar cell using the electron transport layer formed by the fullerene derivative provided in the embodiments of the present invention has a photoelectric conversion efficiency of 11.41%, demonstrating the possibility of fullerene derivatives as electron transport materials. The perovskite solar cell using the modified layer formed by the fullerene derivative provided in the embodiments of the present invention has a photoelectric conversion efficiency of 21.34%, higher than the efficiency of Comparative Example 1 (fullerene C60, 20.56%). The improvement in open-circuit voltage (1.20→1.23V) and short-circuit current (20.74→21.15mA / cm2) fully demonstrates that the fullerene derivative, when used as a modified layer, effectively passivates interface defects on the perovskite layer, reduces carrier recombination, and improves carrier mobility. The formation of a smooth, dense modified layer can improve the interface defects and contact between the perovskite film and C60, improving the operability of related perovskite solar cell devices. This demonstrates the great potential of the fullerene derivatives formed by modifying BCP and its derivatives with fullerene provided in the embodiments of the present invention as electron transport and intermediate modified layers.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fullerene derivative, characterized in that, It comprises a fullerene moiety and a BCP and its derivative moiety, wherein the fullerene moiety and the BCP and its derivative moiety are chemically bonded together.

2. The fullerene derivative according to claim 1, characterized in that, The BCP and its derivatives are partially derived from any one of the compounds shown in the following structural formulas: The fullerene is derived from C20-C100 fullerenes.

3. The fullerene derivative according to claim 2, characterized in that, The chemical bond is achieved by the fullerene moiety and the BCP and its derivative moiety through a dipole cycloaddition of an aldehyde group.

4. The fullerene derivative according to any one of claims 1-3, characterized in that, The fullerene derivatives are selected from compounds shown in the following structural formulas: R1 and R2 are each independently selected from C1-C5 alkyl groups.

5. The fullerene derivative according to claim 4, characterized in that, R1 and R2 are each independently selected from C1-C3 alkyl groups.

6. The fullerene derivative according to claim 4, characterized in that, The fullerene derivatives are selected from compounds shown in the following structural formulas:

7. A method for preparing a fullerene derivative according to any one of claims 1-6, characterized in that, include: The fullerene feedstock that forms the fullerene moiety and the feedstock that forms the BCP and its derivative moiety are reacted to form the fullerene moiety and the BCP and its derivative moiety, and the two are chemically bonded.

8. The preparation method according to claim 7, characterized in that, include: The fullerene raw material, the raw material forming BCP and its derivatives, and sarcosine and its derivatives are mixed and subjected to a Prato reaction. The molar ratio of the raw material forming BCP and its derivatives to the fullerene raw material is 1:(1-10); The molar ratio of the raw material forming BCP and its derivatives to the sarcosine and its derivatives is 1:(1-1.5); The reaction temperature is 100-190℃, and the reaction time is 12-20 hours.

9. A solar cell, characterized in that, It includes a functional layer formed from the fullerene derivative as described in any one of claims 1-6.

10. The solar cell according to claim 9, characterized in that, The solar cell is a perovskite single-cell cell or a perovskite tandem cell. The functional layer is an electron transport layer or a modification layer, wherein the modification layer is located between the electron transport layer and the perovskite layer.

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