Fullerene-based derivative, preparation method and application thereof, and perovskite solar cell

Abstract

This invention provides a fullerene-based derivative, its preparation method, and applications, as well as perovskite solar cells, relating to the field of optoelectronic materials and devices. The fullerene-based derivative provided by this invention comprises a fullerene and a graft group grafted onto the fullerene, wherein the graft group has the structure shown in Formula I. The fullerene-based derivative provided by this invention has multiple peripheral hole transport channels, which is beneficial for hole extraction and transport; wherein R is one of fluorenyl, aromatic amino, carbazole, and porphyrinyl, possessing abundant functional groups and good molecular solubility. Furthermore, this fullerene-based derivative can undergo intramolecular electron transfer, i.e., electrons can be transferred from the peripheral donor to the fullerene acceptor, thereby improving conductivity; simultaneously, this fullerene-based derivative exhibits high thermal stability. The fullerene-based derivative provided by this invention exhibits good device performance in both conventional and trans-perovskite solar cells.

Description

Technical Field

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

[0002] In recent years, organic-inorganic hybrid perovskite solar cells have developed rapidly, attracting widespread attention due to their advantages such as excellent light absorption coefficient, tunable band gap, suitable bandgap width, high charge mobility and long charge diffusion length.

[0003] A typical perovskite solar cell structure generally includes a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and metal electrodes. The hole transport layer, acting as a carrier transport channel, extracts and transports holes, while also preventing moisture erosion of the perovskite in the light-absorbing layer. Currently, Spiro-OMeTAD is a commonly used hole transport material in formal perovskite solar cells; however, its intrinsic conductivity and hole mobility are low, failing to meet device requirements. Typically, a large amount of lithium salt is doped to improve conductivity, but hygroscopic lithium salts accelerate the degradation of perovskite in the light-absorbing layer, leading to reduced stability of the perovskite solar cell.

[0004] The structure of an inverted perovskite solar cell generally includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole-blocking layer, and a metal electrode. The hole transport layer also serves as a channel for carrier transport, extracting and transporting holes. In inverted perovskite solar cells, defects at the interface between the perovskite light-absorbing layer and the charge transport layer are key factors limiting their efficiency and stability. Studies have shown that modifying the interface with organic materials can promote the extraction and transport of photogenerated carriers at the interface; however, commonly used organic materials typically have poor conductivity (such as undoped PTAA and Spiro-OMeTAD). Therefore, designing and synthesizing novel hole transport materials with high hole mobility is crucial for improving the performance of perovskite solar cells. Summary of the Invention

[0005] The purpose of this invention is to provide a fullerene-based derivative, its preparation method and application, and a perovskite solar cell. The thin film prepared using the fullerene-based derivative provided by this invention has excellent hole transport performance, and the prepared perovskite solar cell exhibits excellent photoelectric conversion efficiency.

[0006] To achieve the objectives of this invention, the following technical solutions are provided:

[0007] A fullerene-based derivative comprising a fullerene and a graft group grafted onto the fullerene, the graft group having the structure shown in Formula I:

[0008]

[0009] In Formula I, R is one of arylamine, fluorenyl, carbazolyl, and porphyrinyl.

[0010] Preferably, the molar ratio of the fullerene to the grafted group is 1:4 to 6.

[0011] Preferably, R is:

[0012]

[0013] This invention also provides a method for preparing the fullerene derivatives described in the above technical solution, comprising the following steps:

[0014] A fullerene intermediate, intermediate 3, copper sulfate, sodium ascorbate, and a fifth organic solvent were mixed and subjected to an azideyne cycloaddition reaction to obtain the fullerene derivative; the structural formula of intermediate 3 is as follows: Wherein R is as defined in Formula I; the fullerene intermediate comprises a fullerene and a bis(6-azidohexyl)2,2-dialkylmalonate group grafted onto the fullerene.

[0015] Preferably, the method for preparing the fullerene intermediate includes the following steps:

[0016] 6-Azide-1-hexanol, triethylamine, malonyl chloride and a first organic solvent are mixed and subjected to an acylation reaction to give intermediate 1;

[0017] The intermediate 1, C 60 The fullerene intermediate is obtained by reacting carbon tetrabromide, 1,8-diazabicycloundec-7-ene, and a second organic solvent with a Binger reaction.

[0018] Preferably, the preparation method of the intermediate 3 includes the following steps:

[0019] Compound 1, trimethylsilylacetylene, a catalyst, cuprous iodide, an alkaline source, and a third organic solvent were mixed and coupled to obtain intermediate 2. The structural formula of compound 1 is XR, where X is a halogen atom and R is as defined in Formula I. The structural formula of intermediate 2 is... Where R is defined as in equation I;

[0020] Intermediate 2, tetrabutylammonium fluoride, and a fourth organic solvent are mixed and subjected to a deprotection reaction to obtain intermediate 3.

[0021] Preferably, the molar ratio of the fullerene intermediate, intermediate 3, copper sulfate and sodium ascorbate is 1:14-15:2-3:7-8.

[0022] Preferably, the temperature of the azidoyne cycloaddition reaction is 20–30°C, and the time is 24–72 h; the azidoyne cycloaddition reaction is carried out under light-protected conditions.

[0023] This invention also provides the application of the fullerene derivatives described in the above technical solution in perovskite solar cells.

[0024] The present invention also provides a perovskite solar cell, including a formal nip structure single-junction perovskite solar cell or an inverted pin structure single-junction perovskite solar cell;

[0025] The formal nip structure single-junction perovskite solar cell includes a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode stacked sequentially.

[0026] The inverted pin structure single-junction perovskite solar cell includes a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode stacked sequentially.

[0027] The raw materials for preparing the hole transport layer in the formal nip structure single-junction perovskite solar cell and the inverse pin structure single-junction perovskite solar cell are the fullerene derivatives described in the above technical solution.

[0028] This invention provides a fullerene-based derivative comprising a fullerene and a graft group grafted onto the fullerene, wherein the graft group has the structure shown in Formula I:

[0029]

[0030] In Formula I, R is one of arylamine, fluorenyl, carbazole, and porphyrinyl groups. The fullerene derivative provided by this invention possesses multiple peripheral hole transport channels, which is beneficial for hole extraction and transport; wherein R is one of arylamine, fluorenyl, carbazole, and porphyrinyl groups, possessing abundant functional groups and good molecular solubility. Furthermore, this fullerene derivative can undergo electron transfer, i.e., electrons can be transferred from the peripheral donor to the fullerene acceptor, thereby improving conductivity; simultaneously, this fullerene derivative exhibits high thermal stability, remaining intact at 400°C in a nitrogen atmosphere.

[0031] The present invention also provides a method for preparing the fullerene derivative described in the above technical solution, comprising a fullerene and a bis(6-azidohexyl)2,2-dialkylmalonic acid ester group grafted onto the fullerene; the fullerene derivative has multiple hole transport channels and a shallow LUMO energy level, which promotes hole extraction and blocks electrons, thereby reducing nonradiative recombination. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a structural diagram of a formal nip structure single-junction perovskite solar cell;

[0034] Figure 2 This is a structural diagram of an inverted pin-structured single-junction perovskite solar cell.

[0035] Figure 3 The mass spectrum of the fullerene derivative F-HTM;

[0036] Figure 4 The JV curve is shown for a formal nip structure single-junction perovskite solar cell.

[0037] Figure 5 This is a JV curve diagram for an inverted pin-structured single-junction perovskite solar cell. Detailed Implementation

[0038] This invention provides a fullerene-based derivative comprising a fullerene and a graft group grafted onto the fullerene, wherein the graft group has the structure shown in Formula I:

[0039]

[0040] In Formula I, R is one of arylamine, fluorenyl, carbazolyl, and porphyrinyl.

[0041] In this invention, the molar ratio of the fullerene to the grafted group is preferably 1:4 to 6, more preferably 1:5. In this invention, when the molar ratio of the fullerene to the grafted group is preferably 1:6, the fullerene-based derivative has the structure shown in Formula II:

[0042] R is defined as in equation I.

[0043] When the molar ratio of the fullerene to the grafted group is preferably 1:4, the fullerene-based derivative has the structure shown in Formula III:

[0044]

[0045] Equation III; where R is as defined in Equation I.

[0046] When the molar ratio of the fullerene to the grafted group is preferably 1:5, the fullerene-based derivative has the structure shown in Formula IV:

[0047]

[0048] Equation IV; where R is defined as in Equation I.

[0049] In this invention, R is preferably:

[0050]

[0051] This invention also provides a method for preparing the fullerene derivatives described in the above technical solution, comprising the following steps:

[0052] A fullerene intermediate, intermediate 3, copper sulfate, sodium ascorbate, and a fifth organic solvent were mixed and subjected to an azideyne cycloaddition reaction to obtain the fullerene derivative; the structural formula of intermediate 3 is as follows: R is defined as in equation I.

[0053] In this invention, unless otherwise specified, all raw materials used in the preparation are preferably commercially available products known to those skilled in the art or prepared using methods known to those skilled in the art.

[0054] This invention involves mixing a fullerene intermediate, intermediate 3, copper sulfate, sodium ascorbate, and a fifth organic solvent to perform an azideyne cycloaddition reaction to obtain the fullerene-based derivative; the structural formula of intermediate 3 is as follows: Wherein R is as defined in Formula I; the fullerene intermediate comprises a fullerene and a bis(6-azidohexyl)2,2-dialkylmalonate group grafted onto the fullerene. In this invention, the molar ratio of the fullerene to the bis(6-azidohexyl)2,2-dialkylmalonate group is preferably 1:4 to 6, more preferably 1:5.

[0055] In this invention, when the molar ratio of the fullerene to bis(6-azidohexyl)2,2-dialkylmalonic acid ester is preferably 1:6, the fullerene intermediate preferably has the structure shown in Formula V:

[0056]

[0057] In this invention, the method for preparing the fullerene intermediate preferably includes the following steps:

[0058] 6-Azide-1-hexanol, triethylamine, malonyl chloride and a first organic solvent were mixed and subjected to an acylation reaction to obtain intermediate 1;

[0059] The intermediate 1, C 60Carbon tetrabromide, 1,8-diazabicycloundec-7-ene, and a second organic solvent are mixed and subjected to a Binger reaction to obtain the fullerene intermediate.

[0060] This invention involves mixing 6-azido-1-hexanol, triethylamine (NEt3), malonyl chloride, and a first organic solvent to perform an acylation reaction, yielding intermediate 1. In this invention, the first organic solvent is preferably dichloromethane (DCM). The molar ratio of 6-azido-1-hexanol, triethylamine, and malonyl chloride is preferably 2–5:2–5:1–2. This invention does not specify the amount of the first organic solvent; any solvent amount known to those skilled in the art for chemical reactions may be used. In this invention, the acylation reaction temperature is preferably 0–25°C; the reaction time is preferably 12–16 hours. In this invention, the acylation reaction is preferably carried out under stirring and a protective gas atmosphere; the protective gas is preferably argon. In this invention, the stirring rate is preferably 600–800 rpm.

[0061] The present invention also preferably involves sequentially extracting, removing the solvent, and purifying the product after the acylation reaction. In the present invention, the extraction reagents are preferably dichloromethane and water. In the present invention, the solvent removal method is preferably vacuum distillation. In the present invention, the purification method is preferably column chromatography; the eluent used in the column chromatography is preferably dichloromethane and ethyl acetate, and the volume ratio of dichloromethane to ethyl acetate is preferably 70:1.

[0062] After obtaining intermediate 1, the present invention will combine intermediate 1 and C 60 Carbon tetrabromide (CBr4), 1,8-diazabicycloundec-7-ene (DBU), and a second organic solvent are mixed and subjected to a Binger reaction to obtain the fullerene intermediate. In this invention, the second organic solvent is preferably o-dichlorobenzene (o-DCB). In this invention, the intermediate 1, C... 60 The molar ratio of CBr4 to DBU is preferably 0.6–1.2:0.1–0.12:10–12:2–2.4, more preferably 0.66–1.11:0.11:11.1:2.21; and even more preferably 0.88:0.11:11.1:2.21. The present invention does not specify the amount of the second organic solvent; any solvent amount known to those skilled in the art in chemical reactions may be used.

[0063] In this invention, it is preferable to first prepare the intermediates 1 and C. 60The mixture is prepared by mixing CBr4 and a second organic solvent and dissolving to obtain a solution. The dissolution time is preferably 5-10 min and the temperature is preferably room temperature. Then, the solution is mixed with DBU and subjected to a Binger reaction to obtain the fullerene intermediate. The Binger reaction time is preferably 3-4 days and the temperature is preferably room temperature.

[0064] The present invention also preferably involves sequentially removing the solvent and purifying the product after the Binger reaction. In the present invention, the solvent removal is preferably performed by vacuum distillation. In the present invention, the purification is preferably performed by column chromatography; the eluent used in the column chromatography is preferably dichloromethane and n-hexane, and the volume ratio of dichloromethane to n-hexane is preferably 7:3.

[0065] In this invention, the structural formula of the intermediate 3 is as follows: R is defined as in equation I.

[0066] In this invention, the preparation method of the intermediate 3 preferably includes the following steps:

[0067] Compound 1, trimethylsilylacetylene (TMSA), a catalyst, cuprous iodide, an alkaline source, and a third organic solvent were mixed and coupled to obtain intermediate 2. The structural formula of compound 1 is XR, where X is a halogen atom and R is as defined in Formula I. The structural formula of intermediate 2 is... Where R is defined as in equation I;

[0068] Intermediate 2, tetrabutylammonium fluoride, and a fourth organic solvent are mixed and subjected to a deprotection reaction to obtain intermediate 3.

[0069] In this invention, compound 1, trimethylsilylacetylene, a catalyst, cuprous iodide, an alkaline source, and a third organic solvent are mixed and coupled to obtain intermediate 2. In this invention, the preferred structural formula of compound 1 is XR, where X is preferably a halogen atom, more preferably -I, -Br, -Cl, or -F, and even more preferably -I; R is as defined in formula I.

[0070] In this invention, when X is preferably -I, the preparation method of compound 1 preferably includes the following steps:

[0071] 3,6-(diphenylamino)carbazole, 1-fluoro-4-iodobenzene, cesium carbonate, and an organic solvent are mixed and dissolved, and a coupling reaction is carried out to obtain compound 1. In this invention, the organic solvent is preferably N,N-dimethylformamide (DMF). In this invention, the temperature of the coupling reaction is preferably 140–160°C, more preferably 150°C; the time is preferably 20–24 h. In this invention, the coupling reaction is preferably carried out under a protective gas and stirring conditions. In this invention, the protective gas is preferably argon or nitrogen; the stirring rate is preferably 600–800 r / min, more preferably 750 r / min.

[0072] The present invention also preferably involves sequentially extracting and purifying the dissolved system. In this invention, the purification method is preferably column chromatography; the eluent used in the column chromatography is preferably dichloromethane and n-hexane, and the volume ratio of dichloromethane to n-hexane is preferably 7:3. In this invention, the extraction method is preferably the same as the extraction method described above.

[0073] In this invention, the catalyst preferably includes one of a palladium catalyst, a platinum catalyst, and an iridium catalyst, more preferably a palladium catalyst, and the palladium catalyst is more preferably Pd(PPh3)4. In this invention, the base source preferably includes one of triethylamine, cesium carbonate, and potassium carbonate, more preferably triethylamine (NEt3). In this invention, the third organic solvent is preferably one of tetrahydrofuran, toluene, and 1,4-dioxane, more preferably tetrahydrofuran, and the tetrahydrofuran is more preferably anhydrous tetrahydrofuran. In this invention, the molar ratio of compound 1, trimethylsilylacetylene, catalyst, cuprous iodide, and base source is preferably 0.5:0.5–0.6:0.02–0.03:0.04–0.06:2–3, more preferably 0.5:0.55:0.025:0.05:2.5. This invention does not specify the amount of the third organic solvent; solvent amounts familiar to those skilled in the art in chemical reactions are acceptable.

[0074] In this invention, the coupling reaction is preferably carried out at a temperature of 66–70°C and for a time of 12–16 hours. The coupling reaction is preferably carried out under a protective gas atmosphere. The protective gas is preferably argon or nitrogen.

[0075] The present invention also preferably involves sequentially extracting and purifying the products after the coupling reaction. In this invention, the purification method is preferably column chromatography; the eluent used in the column chromatography is preferably dichloromethane and n-hexane, and the volume ratio of dichloromethane to n-hexane is preferably 7:3. In this invention, the extraction method is consistent with the extraction method described above.

[0076] After obtaining intermediate 2, the present invention mixes intermediate 2, tetrabutylammonium fluoride (TBAF), and a fourth organic solvent to carry out a deprotection reaction to obtain intermediate 3. In the present invention, the molar ratio of intermediate 2 to tetrabutylammonium fluoride is preferably 0.3–0.4:0.45–0.55, more preferably 0.356:0.5. In the present invention, the fourth organic solvent is preferably the same as the third organic solvent. In the present invention, the temperature of the deprotection reaction is preferably room temperature, and the time is preferably 1–2 hours. In the present invention, the deprotection reaction preferably includes the removal of the organic solvent; the method of removing the organic solvent is preferably vacuum distillation.

[0077] The present invention also preferably involves sequentially extracting and purifying the product after removal of the organic solvent. In this invention, the purification method is preferably column chromatography; the eluent used in the column chromatography is preferably dichloromethane and n-hexane, and the volume ratio of dichloromethane to n-hexane is preferably 7:3. In this invention, the extraction method is preferably the same as the extraction method described above.

[0078] In this invention, the copper sulfate is preferably copper sulfate pentahydrate (CuSO4·5H2O).

[0079] In this invention, the fifth organic solvent is preferably chloroform (CHCl3), ethanol, and water. The volume ratio of chloroform, ethanol, and water is preferably 5–7:5–7:1–3, more preferably 6:6:2.

[0080] In this invention, the molar ratio of the fullerene intermediate, intermediate 3, copper sulfate, and sodium ascorbate is preferably 0.025:0.3-0.4:0.05-0.07:0.18-0.19, more preferably 0.025:0.358:0.062:0.185. This invention does not specify the amount of the fifth organic solvent; any solvent amount known to those skilled in the art in chemical reactions may be used.

[0081] In this invention, the preferred method for mixing the fullerene intermediate, intermediate 3, copper sulfate, sodium ascorbate, and the fifth organic solvent is as follows: intermediate 3 is mixed with chloroform to obtain an intermediate 3 solution; the fullerene intermediate is mixed with chloroform to obtain a fullerene intermediate solution; the intermediate 3 solution and the fullerene intermediate solution are mixed to obtain a mixed system; then ethanol, water, copper sulfate, and sodium ascorbate are sequentially mixed with the mixed system.

[0082] In this invention, the preferred temperature for the azidoyne cycloaddition reaction is 25–30°C; the preferred time is 24–72 h, more preferably 48 h. In this invention, the azidoyne cycloaddition reaction is preferably carried out under light-protected, protective gas, and stirring conditions. In this invention, the protective gas is preferably argon or nitrogen. In this invention, the stirring rate is preferably 600–800 r / min, more preferably 750 r / min.

[0083] The present invention also preferably involves sequentially extracting, drying, and purifying the product of the azidoyne cycloaddition reaction. In the present invention, the extraction reagent is preferably dichloromethane and water; the extraction process further preferably includes washing the extracted organic phase with brine. In the present invention, the drying method is preferably to dry the extracted organic phase with anhydrous magnesium sulfate, followed by filtration and then vacuum distillation to remove the organic solvent. In the present invention, the purification method is preferably to sequentially perform column chromatography separation and precipitation; the eluent used in the column chromatography separation is preferably dichloromethane and ethyl acetate, with a preferred volume ratio of dichloromethane to ethyl acetate of 70:1. In the present invention, it is preferable to dissolve the column chromatography product in dichloromethane, and then add pentane dropwise to precipitate it, which is recorded as one precipitation. In the present invention, the number of precipitation cycles is preferably 3 to 5.

[0084] This invention also provides the application of the fullerene derivatives described in the above technical solution in perovskite solar cells.

[0085] The present invention also provides a perovskite solar cell, including a formal nip structure single-junction perovskite solar cell or an inverted pin structure single-junction perovskite solar cell;

[0086] The formal nip structure single-junction perovskite solar cell sequentially comprises a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode.

[0087] The inverted pin structure single-junction perovskite solar cell comprises, in sequence, a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode.

[0088] The raw materials for preparing the hole transport layer in the formal nip structure single-junction perovskite solar cell and the inverse pin structure single-junction perovskite solar cell are the fullerene derivatives described in the above technical solution.

[0089] In this invention, the formal nip structure single-junction perovskite solar cell sequentially comprises a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode; the raw material for preparing the hole transport layer in the formal nip structure single-junction perovskite solar cell is the fullerene-based derivative described in the above technical solution.

[0090] The present invention describes a formal nip structure single-junction perovskite solar cell comprising a substrate. In this invention, the substrate preferably comprises one of an ITO glass substrate, an FTO substrate, a quartz glass substrate, an AZO substrate, a PET substrate, and a PEN substrate. The present invention does not specify the source of the ITO glass substrate; any ITO glass substrate well-known to those skilled in the art for preparing solar cells can be used. The present invention also preferably cleans the ITO glass substrate. In this invention, the cleaning preferably comprises: sequentially ultrasonically cleaning with deionized water, isopropanol, acetone, and ethanol, followed by ultraviolet ozone cleaning, to obtain a pretreated ITO glass substrate. In this invention, the ultrasonic cleaning time for each reagent is preferably 10–20 min; the ultraviolet ozone cleaning time is preferably 15–30 min, more preferably 20 min.

[0091] The formal nip structure single-junction perovskite solar cell described in this invention includes an electron transport layer disposed on one side of the substrate. In this invention, the electron transport layer is preferably formed by spin-coating SnO2.

[0092] The formal nip structure single-junction perovskite solar cell described in this invention includes a perovskite light-absorbing layer disposed on the surface of the electron transport layer. In this invention, the raw materials for preparing the perovskite light-absorbing layer preferably include cesium iodide (CsI), lead iodide (PbI2), methylamine iodide (MAI), methylamine bromide (MABr), methylamine chloride (MACl), formamidinium hydroiodate (FAI), and an organic solvent; the organic solvent is preferably N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or isopropanol (IPA). In this invention, the mass ratio of cesium iodide (CsI), lead iodide (PbI2), methylamine iodide (MAI), methylamine bromide (MABr), methylamine chloride (MACl) to formamidinium hydroiodate (FAI) is preferably 19-20:691-692:5:5-6:18:118-119, more preferably 19.5:691.5:5:5.6:18:118.6.

[0093] In this invention, the preparation method of the perovskite light-absorbing layer includes the following steps: mixing CsI, PbI2, and an organic solvent, dissolving them, and then spin-coating to obtain an ITO / SnO2 / PbI2 structure; mixing MAI, MABr, MACl, FAI, and an organic solvent, dissolving them, and then spin-coating to obtain a perovskite light-absorbing layer on the surface of the electron transport layer. In this invention, the dissolution time is preferably 10–12 h; the dissolution is preferably carried out under stirring conditions; and the stirring rate is preferably 700–800 rpm.

[0094] The formal NIP structure single-junction perovskite solar cell described in this invention includes a hole transport layer disposed on the surface of the perovskite light-absorbing layer. In this invention, the hole transport layer is preferably formed by spin-coating a fullerene derivative, LiTFSI, and 4-tert-butylpyridine (t-BP) dissolved in chlorobenzene, as described in the above-mentioned technical solution. In this invention, it is preferred to first dissolve the fullerene derivative in chlorobenzene to obtain a fullerene derivative solution; then mix the fullerene derivative solution with LiTFSI and t-BP to obtain a spin-coating solution. In this invention, the concentration of the fullerene derivative solution is preferably 30–35 mg / mL. In this invention, the volume ratio of the fullerene derivative solution, LiTFSI, and t-BP is preferably 1:0.016–0.018:0.025–0.030, more preferably 1:0.0164:0.0278.

[0095] The formal NIP structure single-junction perovskite solar cell described in this invention includes a metal electrode disposed on the surface of the hole transport layer. In this invention, the metal electrode is preferably a silver electrode. In this invention, the thickness of the silver electrode is preferably 80–100 nm. In this invention, the silver electrode is preferably prepared by vapor deposition, and the vapor deposition pressure is preferably 5.5 × 10⁻⁶. -4 Pa.

[0096] In this invention, the inverted pin structure single-junction perovskite solar cell sequentially comprises a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode.

[0097] The inverted pin structure single-junction perovskite solar cell of the present invention includes a substrate, which is preferably the same as the substrate in the above-mentioned formal nip structure single-junction perovskite solar cell.

[0098] The inverse pin-structured single-junction perovskite solar cell of this invention includes a hole transport layer disposed on one side of the substrate. Preferably, the hole transport layer comprises an inorganic hole transport layer and an organic hole transport layer stacked sequentially; the inorganic hole transport layer is preferably in contact with the substrate. Preferably, the inorganic hole transport layer is formed by spin-coating an aqueous solution of nano-nickel oxide. Preferably, the organic hole transport layer is formed by spin-coating a fullerene-based derivative as described in the above-mentioned technical solution dissolved in chlorobenzene.

[0099] The inverse pin-structured single-junction perovskite solar cell of this invention includes a perovskite light-absorbing layer disposed on the surface of the hole transport layer. In this invention, the raw materials for preparing the perovskite light-absorbing layer preferably include FAI, MABr, CsI, PbBr2, PbI2, and an organic solvent; the organic solvent is preferably N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). In this invention, the mass ratio of FAI, MABr, CsI, PbBr2, and PbI2 is preferably 232–233:8:19–20:28–29:669–670, more preferably 232.8:8:19.5:28.2:669.9.

[0100] In this invention, the preparation method of the perovskite light-absorbing layer includes the following steps: mixing FAI, MABr, CsI, PbBr2, PbI2 and an organic solvent, dissolving them, and then spin-coating the mixture; then adding anisole to obtain the perovskite light-absorbing layer on the surface of the hole transport layer. In this invention, the dissolution time is preferably 2–3 hours; the dissolution is preferably carried out under stirring conditions; and the stirring rate is preferably 700–800 rpm.

[0101] The present invention does not impose any particular limitation on the spin coating method, and any method well known to those skilled in the art can be used. In the present invention, the spin coating rate is preferably 500-4000 rpm, more preferably 1000-3000 rpm, and most preferably 2000 rpm; the spin coating time is preferably 5-30 s, more preferably 10-20 s.

[0102] In this invention, the spin coating process preferably includes an annealing treatment. In this invention, the annealing temperature is preferably 100–150°C; the time is preferably 1–30 min, more preferably 10–15 min. In this invention, the annealing is preferably performed in an air environment or a nitrogen environment.

[0103] The inverted pin-structured single-junction perovskite solar cell of this invention includes an electron transport layer disposed on the surface of the perovskite light-absorbing layer. In this invention, the electron transport layer is preferably made of C... 60 Formed by vapor deposition. In this invention, the vapor deposition pressure is preferably 5.5 × 10⁻⁶. -4 Pa.

[0104] The inverted pin structure single-junction perovskite solar cell of this invention includes a hole-blocking layer disposed on the surface of the electron transport layer. In this invention, the hole-blocking layer is preferably formed by vapor deposition of bath copper flux (BCP).

[0105] The inverted pin-structured single-junction perovskite solar cell of this invention includes a metal electrode disposed on the surface of the hole-blocking layer. In this invention, the metal electrode is preferably a silver electrode, the thickness of the silver electrode is preferably 80–100 nm, and the silver electrode is preferably prepared by vapor deposition, with the vapor deposition pressure preferably being 5.5 × 10⁻⁶. -4 Pa.

[0106] To further illustrate the present invention, the fullerene-based derivatives and perovskite solar cells provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0107] Example 1

[0108] The fullerene derivative F-HTM was prepared with the following chemical structural formula:

[0109]

[0110] The reaction formula for preparing the fullerene derivative F-HTM is as follows:

[0111]

[0112]

[0113] The preparation method of intermediate 3 is as follows:

[0114] 0.74 mol of 3,6-(diphenylamino)carbazole (460 mg), 2.96 mol of 1-fluoro-4-iodobenzene (658 mg), and 2.96 mmol of cesium carbonate (965 mg) were weighed and dissolved in 10 mL of DMF. The mixture was reacted at 750 rpm, 150 °C, and argon for 24 h. After cooling to room temperature, the mixture was extracted with dichloromethane and water. The residue was concentrated by rotary evaporation and then purified by column chromatography (dichloromethane to n-hexane volume ratio of 7:3) to obtain 481 mg of bright green solid (compound 1), with a yield of 79%.

[0115] Weigh 0.5 mol of compound 1 (412 mg), 0.05 mmol of cuprous iodide (9.6 mg), and 2.5 mmol of triethylamine (253 mg), dissolve them in 10 mL of anhydrous tetrahydrofuran under argon atmosphere, and then degas under an argon atmosphere for 15 min to obtain a mixed solution; then mix 0.025 mmol of Pd(PPh3)4 (30 mg) and 0.55 mmol of TMSA (54 mg) with the above mixed solution, reflux at 70 °C for 6 h, cool to room temperature, remove anhydrous tetrahydrofuran under reduced pressure, extract with dichloromethane and water, concentrate by rotary evaporation, and separate and purify the residue by column chromatography (dichloromethane to n-hexane volume ratio of 7:3) to obtain 310 mg of orange-yellow solid (intermediate 2), with a yield of 78%;

[0116] 0.356 mmol of intermediate 2 (284 mg) was weighed and dissolved in 10 mL of anhydrous tetrahydrofuran. Then, 0.5 mmol of 1 M TBAF solution (500 μL, anhydrous tetrahydrofuran) was added. The mixture was stirred at room temperature and 750 rpm for 1 h. After removing the anhydrous tetrahydrofuran under reduced pressure, the mixture was extracted with dichloromethane and water. The residue was concentrated by rotary evaporation and then purified by column chromatography (dichloromethane to n-hexane volume ratio 7:3) to obtain 241 mg of yellow powder (intermediate 3), with a yield of 94%. The NMR and CMR data of intermediate 3 are as follows:

[0117] 1 H-NMR (500MHz, d6-DMSO): δ [ppm] = 7.72 (d, J = 8.45Hz, 2H), 7.67 (d, J = 2.0Hz, 2H), 7.60 (d, J = 8.45Hz, 2H), 7.32 (d, J = 8.8H z,2H),7.07-7.05(dd,J1=8.8Hz,J2=2.05Hz,2H),6.85-6.79(dd,J1=22.6Hz,J2=9.1Hz,16H),4.34(s,1H),3.68(s,12H).

[0118] 13 C-NMR (125MHz, d6-DMSO): δ [ppm] = 154.56, 142.06, 141.80, 137.59, 136.83, 133.67, 1 26.81,124.57,124.23,123.84,120.64,116.53,114.89,110.96,83.09,81.85,55.37.

[0119] The preparation method of fullerene intermediates is as follows:

[0120] Weigh 10 mmol of 6-azido-1-hexanol (1.432 g) and 10 mmol of NEt3 (1.01 g) and dissolve them in 40 mL of DCM at 0 °C under argon atmosphere. Then, add 4 mmol of malonyl chloride (564 mg) to 5 mL of DCM over 1 min and stir at 0 °C and 600 rpm for 1 h. Then, heat to room temperature at 5 °C / min overnight. Extract with dichloromethane and water. After removing the solvent by vacuum distillation, separate and purify the residue by column chromatography (dichloromethane to ethyl acetate volume ratio of 70:1) to obtain 1.16 g of pale yellow oil (intermediate 1) with a yield of 82%.

[0121] Weigh 0.11 mmol C 60 80 mg of DBU, 1.11 mmol of intermediate 1 (392 mg), and 11.1 mmol of CBr4 (3.67 g) were dissolved in 33 mL of o-DCB. The mixture was stirred at 850 rpm, room temperature, and under argon atmosphere for 5 min. Then, 2.21 mmol of DBU (337 mg) was added, and the mixture was stirred at 850 rpm, room temperature, for 72 h. The o-DCB solvent was removed by vacuum distillation. The remaining organic phase was purified by column chromatography (dichloromethane to ethyl acetate, volume ratio 70:1) to obtain 142 mg of a red glassy membrane (fullerene intermediate), with a yield of 45%. The intermediate was then stored in toluene solution under refrigeration for later use. The NMR and CMR data of the fullerene intermediate are as follows:

[0122] 1 H-NMR (500MHz, CDCl3): δ [ppm] = 4.26 (t, J = 6.65Hz, 24H), 3.27 (t, J = 6.85Hz, 24H), 1.74-1.34 (96H).

[0123] 13 C-NMR (125MHz, CDCl3): δ [ppm] = 163.77, 145.74, 141.14, 69.13, 66.73, 51.29, 45.46, 28.74, 28.33, 26.29, 25.44.

[0124] The preparation method of the fullerene derivative F-HTM is as follows:

[0125] Under argon atmosphere, 0.358 mmol of intermediate 3 (259 mg) was weighed and dissolved in 6 mL of CHCl3 to obtain intermediate 3 solution;

[0126] Weigh 0.025 mmol of the above fullerene intermediate (70 mg) and dissolve it in 6 mL of CHCl3 to obtain a fullerene intermediate solution;

[0127] The intermediate 3 solution and the fullerene intermediate solution were mixed to obtain a mixed system. Then, 6 mL of ethanol, 2 mL of H2O, 0.062 mmol of CuSO4·5H2O (15.4 mg), and 0.185 mmol of sodium ascorbate (36.7 mg) were added sequentially to the mixed system. The azidoyne cycloaddition reaction was carried out at 25 °C, 750 rpm, and in the dark for 72 h. The mixture was extracted with dichloromethane and water. The extracted organic phase was washed with brine and dried with Na2SO4. After filtration, the organic solvent in the filtrate was removed by vacuum distillation. The residue was separated and purified by column chromatography (dichloromethane to ethyl acetate in a volume ratio of 70:1). The purified product (brown glass membrane) was dissolved in dichloromethane, and pentane was added to precipitate it. After solid-liquid separation, 144 mg of the fullerene derivative F-HTM was obtained. F-HTM was a light brown powder with a yield of 50%. The NMR, CMR, and mass spectrometry data of the fullerene derivative F-HTM are as follows:

[0128] 1 H-NMR (500MHz, C6D6): δ [ppm] = 8.07 (s, 24H), 7.83 (s, 24H), 7.63 (s, 12H), 7.39 (s, 24H), 7.22 (s, 48H), 7.05 (s, 96H) ,6.68(s,96H),4.03(d,J=31.5Hz,48H),3.32(s,144H),1.63(s,24H),1.27-1.24(m,24H),4.03(d,J=34.85Hz,48H).

[0129] 13 C-NMR (125MHz, C6D6): δ [ppm] = 163.94, 155.39, 147.07, 146.51, 143.03, 142.47, 138.09, 137.75, 130.55, 128.35, 127 .47,125.55,124.75,120.42,117.69,115.08,111.20,70.40,67.20,55.14,50.19,47.35,30.39,28.41,26.21,25.56.

[0130] MALDI-TOF m / z for C 726 H 612 N 72 O 72 [M+Na] + 11520.1; found 11520.9.

[0131] Example 2

[0132] Cleaning the ITO glass substrate: The ITO glass substrate was ultrasonically cleaned for 20 minutes each with deionized water, isopropanol, acetone and ethanol, respectively, and then cleaned with ultraviolet ozone for 30 minutes to obtain the pretreated ITO glass substrate.

[0133] Spin-coating electron transport layer: SnO2 solution was spin-coated on the surface of pretreated ITO glass substrate at 4000 rpm for 20 s, and then annealed at 150 °C for 15 min to obtain an electron transport layer with a thickness of 30 nm on the surface of ITO glass substrate. Then it was transferred to a nitrogen glove box.

[0134] Spin-coating the perovskite light-absorbing layer: 19.5 mg CsI and 691.5 mg PbI2 were dissolved in 1000 μL of a mixed organic solvent of DMF and DMSO (900 μL DMF + 100 μL DMSO). After stirring at 600 rpm for 12 h, the solution was filtered to obtain the first spin-coating solution. The first spin-coating solution was then spin-coated onto the surface of the electron transport layer at 2000 rpm for 30 s, and then annealed at 70 °C for 1 min under nitrogen atmosphere to obtain the ITO / SnO2 / PbI2 structure. 5 mg MAI, 5.6 mg MABr, 18 mg MACl, and 118.6 mg... FAI was dissolved in 2 mL of isopropanol solvent to obtain a second spin coating solution. The second spin coating solution was then spin coated on the surface of the above ITO / SnO2 / PbI2 structure at 4000 rpm for 30 s. Then, it was annealed at 150 °C for 15 min in air atmosphere to obtain a perovskite light-absorbing layer with a thickness of 650 nm on the electron transport layer surface. Then, it was transferred to a nitrogen glove box.

[0135] Spin-coating hole transport layer: Weigh 35 mg of F-HTM described in Example 1 and dissolve it in 1 mL of chlorobenzene. Then add 16.4 μL of LiTFSI and 27.8 μL of t-BP, mix well to obtain a spin-coating solution, and spin-coat the above perovskite light-absorbing layer at 3000 rpm for 30 s to obtain a hole transport layer with a thickness of 60 nm on the surface of the perovskite light-absorbing layer.

[0136] Fabrication of metal electrodes: at 5.5 × 10⁻⁶ -4 Under Pa conditions, a 95 nm thick layer of silver was deposited on the surface of the hole transport layer as an electrode, resulting in an effective area of ​​0.119 cm². 2 The formal nip structure single-junction perovskite solar cell, the structure of which is as follows: Figure 1 As shown.

[0137] Example 3

[0138] Cleaning the ITO glass substrate: The ITO glass substrate was ultrasonically cleaned for 20 minutes each with deionized water, isopropanol, acetone and ethanol, respectively, and then cleaned with ultraviolet ozone for 30 minutes to obtain the pretreated ITO glass substrate.

[0139] Spin-coating inorganic hole transport layer: 10 mg / mL nano nickel oxide aqueous dispersion was spin-coated on the surface of pretreated ITO glass substrate at 4000 rpm for 20 s, and then annealed at 150 °C for 10 min in air to obtain an inorganic hole transport layer with a thickness of 30 nm on the surface of ITO glass substrate, and then transferred to a nitrogen glove box.

[0140] Spin-coating organic hole transport layer: Weigh 1 mg of F-HTM described in Example 1 and dissolve it in 1 mL of chlorobenzene. After mixing evenly, a spin-coating solution is obtained. Spin-coating solution is applied to the inorganic hole transport layer at 3000 rpm for 30 s. Then, it is annealed at 100 °C for 10 min in a nitrogen atmosphere to obtain an organic hole transport layer with a thickness of 2 nm on the surface of the inorganic hole transport layer.

[0141] Spin-coated perovskite light-absorbing layer: Weigh 232.8 mg FAI, 8 mg MABr, 19.5 mg CsI, 28.2 mg PbBr2 and 669.9 mg PbI2 and dissolve them in a mixed organic solvent of 1000 μL LMF and DMSO (800 μL LMF + 200 μL LDMSO). Stir at 500 rpm for 30 min and then filter to obtain perovskite precursor solution. Spin-coat the obtained perovskite precursor solution on the surface of hole transport layer at 1000 rpm for 5 s, and then continue spin-coating at 500 rpm for 30 s. In the last 6 s, drop 150 μL anisole as antisolvent. Finally, anneal at 100 °C for 30 min to obtain a perovskite light-absorbing layer with a thickness of 600 nm on the surface of hole transport layer.

[0142] Fabrication of the electron transport layer: at 5.5 × 10⁻⁶ -4 Under Pa conditions, a C layer with a thickness of 30 nm is deposited on the surface of the perovskite light-absorbing layer. 60 Electron transport layer;

[0143] Preparation of hole-blocking layer: at 5.5 × 10 -4 Under Pa conditions, a BCP hole blocking layer with a thickness of 8 nm is deposited on the surface of the electron transport layer.

[0144] Fabrication of metal electrodes: at 5.5 × 10⁻⁶ -4 Under Pa conditions, a 100 nm thick layer of silver is deposited on the surface of the hole-blocking layer as an electrode to obtain an inverted pin-structured single-junction perovskite solar cell. The structure of the inverted pin-structured single-junction perovskite solar cell is as follows: Figure 2 As shown.

[0145] Comparative Example 1

[0146] A formal nip structure single-junction perovskite solar cell was prepared according to the preparation method of Example 2, the only difference being that the material in the spin-coating hole transport layer step was changed to Spiro-OMeTAD; the specific steps are as follows:

[0147] Spin-coating hole transport layer: Weigh 90 mg of Spiro-OMeTAD described in Example 1 and dissolve it in 1 mL of chlorobenzene. Then add 21.8 μL of LiTFSI and 37 μL of t-BP, mix well to obtain a spin-coating solution, and spin-coate the solution onto the perovskite light-absorbing layer at 3000 rpm for 30 s without annealing. A hole transport layer with a thickness of 150 nm is obtained on the surface of the perovskite light-absorbing layer. This photovoltaic device is named Spiro-OMeTAD.

[0148] Comparative Example 2

[0149] A reverse pin-structured single-junction perovskite solar cell was prepared according to the preparation method of Example 3, the only difference being that the organic hole transport layer prepared by F-HTM as described in Example 1 was not spin-coated. This photovoltaic device was named NiOx.

[0150] Test Example 1

[0151] Intermediate 3, fullerene intermediate, and fullerene derivative F-HTM prepared in Example 1 were characterized.

[0152] Figure 3 The mass spectrum of the fullerene derivative F-HTM described in Example 1 is obtained from... Figure 3 It can be seen that the fullerene derivative in Example 1 was obtained.

[0153] Test Example 2

[0154] The photovoltaic performance of the forward / reverse nip / pin structure single-junction perovskite solar cells prepared in Examples 1-2 and Comparative Examples 1-2 was tested. The test results are shown in Tables 1-2 and 2. Figures 4-5 As shown.

[0155] Table 1. Photovoltaic performance test results of formal NIP structure single-junction perovskite solar cells.

[0156] Spiro-OMeTAD 1.139 25.01 82.29 23.44 F-HTM 1.147 25.03 82.61 23.71

[0157] Figure 4 This is the JV curve of a formal nip structure single-junction perovskite solar cell, from... Figure 4The results show that the fullerene-based hole transport material provided by this invention has a higher photoelectric conversion efficiency in actual devices than the traditional hole transport material Spiro-OMeTAD, making it a very promising hole transport material.

[0158] Table 2. Photovoltaic performance test results of inverted pin structure single-junction perovskite solar cells.

[0159]

[0160]

[0161] Figure 5 This is a JV curve diagram of an inverted pin-structured single-junction perovskite solar cell, from... Figure 5 The results show that the inverted device achieved higher photoelectric conversion efficiency after the addition of the organic hole transport layer F-HTM.

[0162] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A fullerene-based derivative, characterized in that, It includes a fullerene and a graft group grafted onto the fullerene, the graft group having the structure shown in Formula I: Equation I; In Equation I, R is or The fullerene is a C60 fullerene; the molar ratio of the fullerene to the grafting group is 1:4~6.

2. The method for preparing the fullerene derivative according to claim 1, characterized in that, The fullerene intermediate comprises a fullerene and a bis(6-azidohexyl)2,2-dialkylmalonate group grafted onto the fullerene; When the molar ratio of the fullerene to bis(6-azidohexyl)2,2-dialkylmalonate is 1:6, the specific structure is as follows: The preparation method of the fullerene derivative includes the following steps: The fullerene intermediate, intermediate 3, copper sulfate, sodium ascorbate, and a fifth organic solvent were mixed and subjected to an azideyne cycloaddition reaction to obtain the fullerene derivative; the structural formula of intermediate 3 is as follows: , where R is defined as in equation I.

3. The preparation method according to claim 2, characterized in that, The method for preparing the fullerene intermediate includes the following steps: 6-Azide-1-hexanol, triethylamine, malonyl chloride, and a first organic solvent were mixed and subjected to an acylation reaction to obtain intermediate 1; the specific structure of intermediate 1 is shown below: ； The intermediate 1, C 60 The fullerene intermediate is obtained by reacting carbon tetrabromide, 1,8-diazabicycloundec-7-ene, and a second organic solvent with a Binger reaction.

4. The preparation method according to claim 2, characterized in that, The preparation method of the intermediate 3 includes the following steps: Compound 1, trimethylsilylacetylene, a catalyst, cuprous iodide, an alkaline source, and a third organic solvent were mixed and subjected to a coupling reaction to obtain intermediate 2; the structural formula of compound 1 is as follows. Where X is a halogen atom, and R is as defined in Formula I; the structural formula of the intermediate 2 is , where R is as defined in Formula I; the catalyst is Pd(PPh3)4; Intermediate 2, tetrabutylammonium fluoride, and a fourth organic solvent are mixed and subjected to a deprotection reaction to obtain intermediate 3.

5. The preparation method according to any one of claims 2 to 4, characterized in that, The molar ratio of the fullerene intermediate, intermediate 3, copper sulfate, and sodium ascorbate is 1:14~15:2~3:7~8.

6. The preparation method according to claim 2, characterized in that, The azidoyne cycloaddition reaction is carried out at a temperature of 20-30°C for 24-72 hours; the azidoyne cycloaddition reaction is carried out under light-protected conditions.

7. The application of the fullerene derivative of claim 1 in perovskite solar cells.

8. A perovskite solar cell, characterized in that, This includes formal nip structure single-junction perovskite solar cells or inverted pin structure single-junction perovskite solar cells; The formal nip structure single-junction perovskite solar cell includes a substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode stacked sequentially. The inverted pin structure single-junction perovskite solar cell includes a substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a metal electrode stacked sequentially. The raw materials for preparing the hole transport layer in the formal nip structure single-junction perovskite solar cell and the inverse pin structure single-junction perovskite solar cell include the fullerene derivatives described in claim 1.

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