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

Abstract

This invention relates to a fullerene derivative, its preparation method and application, and a tin-based perovskite solar cell photovoltaic device, belonging to the field of optoelectronic materials and devices technology. The fullerene derivative of this invention has the structure shown in Formula I; in Formula I, X... ‑ It is a halide ion or pseudohalogen ion; R is an alkenyl, four-membered cycloalkyl, or dithiocyclopentyl; Fu is C 60 C 70 C 84 Alternatively, it can be an embedded metallofullerene. In the fullerene derivatives of this invention, R is an alkenyl, a four-membered cycloalkyl, or a dithiocyclopentyl group. R can open double bonds or open rings to form polymers. Furthermore, the thiol group after ring opening of the dithiocyclopentyl group and the carbonyl group in the structure can form coordination bonds with divalent tin ions in tin-based perovskite solar cells, thereby regulating the crystallization rate of perovskite and reducing the lattice stress of perovskite. At the same time, the fullerene derivatives have good solubility, reducing the lattice stress generated by rapid crystallization of the perovskite active layer, and further improving the stability of tin-based perovskite solar cells.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic materials and devices, and particularly relates to a fullerene derivative, a preparation method and application thereof, and a tin-based perovskite solar cell. BACKGROUND

[0002] The perovskite solar cell is a solar cell using an organic metal halide semiconductor material with a perovskite crystal structure as a light-absorbing layer. Compared with traditional photovoltaic devices, the perovskite solar cell is more suitable for manufacturing flexible devices due to the thin film preparation characteristics of the light-absorbing layer, and can be widely used in portable power sources. On the other hand, the perovskite solar cell can be combined into a rigid module for large-scale photovoltaic devices as a flexible device with continuous, low-cost and manufacturable flexibility. However, the toxicity of lead has been a hindrance to the further commercial development of the perovskite solar cell, which makes many researchers explore and find a substitute element for lead as a substitution element in the B position of the perovskite crystal structure ABX3 to develop a non-toxic and environmentally friendly perovskite solar cell.

[0003] The tin element is in the same main group as the lead element, has a similar electronic configuration, and the ionic radius of the divalent tin ion (Sn 2+ ) is similar to the ionic radius of the lead ion (Pb 2+ ), which is (Sn ) and (Pb ), respectively. This makes the tin-based perovskite have most of the excellent photoelectric properties of the lead-based perovskite. The tin-based perovskite has the advantages of a suitable optical band gap (1.2-1.4 eV), a strong light absorption coefficient, a low exciton binding energy and a high carrier mobility (10 2 -10 3 cm -2 V -1 s -1 ), etc. among many lead-free perovskites. However, the existing tin-based perovskite solar cell (FASnI3 or MASnI3) has a large amount of residual stress and defects in the perovskite active layer due to the too fast perovskite crystallization rate, has poor stability, and thus the photoelectric conversion efficiency of the current tin-based perovskite solar cell is low, and the highest conversion efficiency of the flexible device is only 8.56%. SUMMARY

[0004] The application provides a fullerene derivative, a preparation method and application thereof, and a tin-based perovskite solar cell. The fullerene derivative provided by the application has excellent stability when applied to the tin-based perovskite solar cell, so that the tin-based perovskite solar cell has a high photoelectric conversion efficiency.

[0005] In order to achieve the object of the application, the application provides the following technical solutions.

[0006] A fullerene derivative having a structure shown in Formula I:

[0007]

[0008] In Formula I, X - is a halide ion or a pseudohalide ion;

[0009] R is an alkenyl group, a tetraalkyl group or a dithiolyl group;

[0010] Fu is C 60 , C 70 , C 84 or a metallofullerene;

[0011] Preferably, X - includes F - , Cl - , Br - , I - , SCN - or CN - .

[0012] Preferably, the alkenyl group includes a vinyl group, a propenyl group or a 2-methyl-1-propenyl group; the tetraalkyl group includes a cyclobutyl group, a methylcyclobutyl group or a 1,1-dimethylcyclobutyl group; and the dithiolyl group has the following structure:

[0013]

[0014] The present application provides a preparation method of the fullerene derivative described in the above technical solution, comprising the following steps:

[0015] Mixing compound 1, 4-hydroxybenzaldehyde, a catalyst and a first organic solvent to perform an esterification reaction to obtain intermediate 1;

[0016] Mixing the intermediate 1, sarcosine, a fullerene source and a second organic solvent to perform an addition reaction to obtain intermediate 2;

[0017] Mixing the intermediate 2, compound 2 and a third organic solvent to perform a quaternary ammonium reaction to obtain the fullerene derivative; the fullerene source is C 60 , C 70 , C 84 or a metallofullerene;

[0018] The compound 1 has a structure shown in Formula II:

[0019] In Formula II, R is defined as in Formula I;

[0020] The chemical formula of the compound 2 is CH3X; X is defined as in Formula I.

[0021] Preferably, the catalyst comprises 4-dimethylaminopyridine and / or dicyclohexylcarbodiimide.

[0022] Preferably, the first organic solvent is tetrahydrofuran; the second and third organic solvents are independently one or more of toluene, chlorobenzene and o-dichlorobenzene.

[0023] This invention provides the application of the fullerene derivatives described in the above technical solutions or the fullerene derivatives prepared by the preparation methods described in the above technical solutions in tin-based perovskite solar cells.

[0024] This invention provides a tin-based perovskite solar cell, comprising a conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a hole blocking layer, and a metal electrode stacked sequentially; the perovskite active layer is doped with the fullerene derivative described in the above technical solution.

[0025] Preferably, the perovskite active layer comprises the following raw materials: fullerene derivatives, stannous iodide, phenethylamine iodide, formamidinic hydroiodic acid, methylamine hydroiodic acid, stannous fluoride, and ammonium thiocyanate.

[0026] Preferably, the mass of the fullerene derivative in the perovskite active layer is 0.2-3% of the total mass of stannous iodide, phenethylamine iodide, and formamidinic hydroiodic acid.

[0027] This invention provides a fullerene derivative having the structure shown in Formula I:

[0028]

[0029] In formula I, X - It is a halide ion or pseudohalogen ion; R is an alkenyl, four-membered cycloalkyl, or dithiocyclopentyl; Fu is C 60 C 70 C 84 Alternatively, it can be an embedded metallofullerene. In the fullerene derivatives provided by this invention, R is alkenyl, a four-membered cycloalkyl, or a dithiocyclopentyl. When R is alkenyl, the double bond opens and polymerizes; when R is a four-membered cycloalkyl or a dithiocyclopentyl, ring-opening can form a polymer. Furthermore, the thiol group after ring-opening of the dithiocyclopentyl and the carbonyl group in the structure can form coordination bonds with divalent tin ions in tin-based perovskite solar cells, thereby regulating the perovskite crystallization rate and reducing the perovskite lattice stress, thus improving the stability of tin-based perovskite solar cells. Simultaneously, the fullerene derivatives provided by this invention have good solubility and can be uniformly dispersed at the grain boundaries of the perovskite active layer in tin-based perovskite solar cells, effectively reducing the lattice stress generated by rapid crystallization of the perovskite active layer, further improving the stability of tin-based perovskite solar cells.

[0030] Further, the fullerene derivative doped in the perovskite active layer of the tin-based perovskite solar cell has good electron extraction capacity, is beneficial to the transfer of electrons in the tin-based perovskite solar cell, and thus improves the photoelectric conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0032] Figure 1 The mass spectrum of the fullerene derivative FTAI;

[0033] Figure 2 The ultraviolet-visible spectrum of the fullerene derivative FTAI;

[0034] Figure 3 The structure diagram of the tin-based perovskite solar cell described in Application Example 1;

[0035] Figure 4 The structure diagram of the tin-based perovskite solar cell described in Comparative Example 2;

[0036] Figure 5 The J-V curve diagram of the tin-based perovskite solar cell described in Application Example 1 and Comparative Example 1;

[0037] Figure 6 The J-V curve diagram of the tin-based perovskite solar cell described in Application Example 2 and Comparative Example 2;

[0038] Figure 7 The photoelectric conversion efficiency statistical diagram of the tin-based perovskite solar cell described in Application Examples 1-2 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0039] The present application provides a fullerene derivative, which has the structure shown in Formula I:

[0040]

[0041] In Formula I, X - is a halogen ion or a pseudo-halogen ion;

[0042] R is an alkenyl group, a four-membered ring alkyl group or a dithiolyl group;

[0043] Fu is C 60 , C 70 , C 84 or an endohedral metallofullerene.

[0044] In the present application, X - is a halide ion or a pseudohalide ion, preferably a halide ion. In the present application, the halide ion preferably includes F - , Cl - , Br - or I - , more preferably I - . In the present application, the pseudohalide ion preferably includes SCN - or CN - . In the present application, the halide ion or the pseudohalide ion can be preferably coordinated with a metal ion, which preferably includes one or more of Sn 2+ , Pb 2+ , Bi 3+ and Ge 2+ , more preferably Sn 2+ . Taking X - as I - and R as dithiolane as an example, the product formed by coordination of the fullerene derivative of the present application with Sn 2+ has the structure shown in formula III:

[0045]

[0046] The fullerene derivative with a halide ion or a pseudohalide ion selected in the present application can enable the perovskite solar cell prepared to have better defect passivation ability, higher device mechanical stability and higher photoelectric conversion efficiency.

[0047] In the present application, R is an alkenyl group, a four-membered ring alkyl group or a dithiolane group, preferably a dithiolane group. In the present application, the dithiolane group has the following structure:

[0048]

[0049] In the present application, the alkenyl group preferably includes a vinyl group, a propenyl group or a 2-methyl-1-propenyl group, more preferably a vinyl group. In the present application, the vinyl group, the propenyl group and the 2-methyl-1-propenyl group have the following structures, respectively:

[0050]

[0051] In the present application, the four-membered ring alkyl group preferably includes a cyclobutyl group, a methylcyclobutyl group or a 1,1-dimethylcyclobutyl group, more preferably a cyclobutyl group. In the present application, the cyclobutyl group, the methylcyclobutyl group or the 1,1-dimethylcyclobutyl group has the following structure:

[0052]

[0053] In the present application, the alkenyl group, the four-membered ring alkyl group and the dithiolyl group can all be self-crosslinked. Taking the dithiolyl group with R as an example, the product formed by self-crosslinking of the fullerene derivative in the present application has the structure shown in Formula IV:

[0054]

[0055] The dithiolyl group in the present application can undergo ring-opening polymerization at 70℃, and the sulfur atom contained therein can form coordination with tin ions, thereby improving the stability of tin ions in tin-based perovskite solar cells.

[0056] In the present application, the Fu is C 60 , C 70 , C 84 or an endohedral metallofullerene, preferably C 60 .

[0057] The present application provides a preparation method of the fullerene derivative in the above technical solution, which comprises the following steps:

[0058] Compound 1, 4-hydroxybenzaldehyde, a catalyst and a first organic solvent are mixed to perform esterification reaction, thereby obtaining intermediate 1;

[0059] The intermediate 1, sarcosine, a fullerene source and a second organic solvent are mixed to perform addition reaction, thereby obtaining intermediate 2;

[0060] The intermediate 2, compound 2 and a third organic solvent are mixed to perform quaternary ammonium reaction, thereby obtaining the fullerene derivative;

[0061] The compound 1 has the structure shown in Formula II:

[0062] In Formula II, R is defined as in Formula I;

[0063] The compound 2 has the chemical formula CH3X; and X is defined as in Formula I.

[0064] In the present application, all the preparation raw materials are preferably commercially available products unless otherwise specified.

[0065] In the present application, compound 1, 4-hydroxybenzaldehyde, a catalyst and a first organic solvent are mixed to perform esterification reaction, thereby obtaining intermediate 1. In the present application, the compound 1 can be specifically lipoic acid. In the present application, the catalyst preferably comprises 4-dimethylaminopyridine and / or dicyclohexyl carbodiimide, and more preferably comprises a mixture of 4-dimethylaminopyridine and dicyclohexyl carbodiimide. In the present application, the first organic solvent is preferably tetrahydrofuran or N,N-dimethylformamide, and more preferably tetrahydrofuran.

[0066] In the present application, the molar ratio of compound 1, 4-hydroxybenzaldehyde, 4-dimethylaminopyridine and dicyclohexyl carbodiimide is preferably 2:2.2-2.5:1.5-2:2.2-2.5, more preferably 2:2.25:1.6:2.25. The present application does not have special provisions for the amount of the first organic solvent, and the amount of solvent used in the chemical reaction well known to those skilled in the art can be used.

[0067] In the present application, the mixing method of compound 1, 4-hydroxybenzaldehyde, catalyst and the first organic solvent is preferably: first mixing compound 1, 4-hydroxybenzaldehyde and the first organic solvent to obtain a first mixed solution; mixing the catalyst and the first organic solvent to obtain a second mixed solution; adding the second mixed solution dropwise to the first mixed solution after cooling. The present application preferably cools the first mixed solution to 0°C in an ice bath, and then adds the second mixed solution dropwise; after the addition of the second mixed solution is completed, the esterification reaction is preferably carried out after stirring at 0°C for 30 minutes. The present application does not have special limitations on the stirring rate, and the conventional stirring rate in the art can be used.

[0068] In the present application, the temperature of the esterification reaction is preferably room temperature. The present application does not have special provisions for the time of the esterification reaction, and the thin layer chromatography (TLC) well known to those skilled in the art can be used for monitoring, which is preferably 1-3 days, more preferably 2 days. The chemical reaction equation of the esterification reaction of the present application is shown in formula V:

[0069]

[0070] After the esterification reaction is completed, the present application also preferably carries out solid-liquid separation on the product of the esterification reaction, and then sequentially removes the organic solvent and separates by chromatography from the liquid phase after the solid-liquid separation to obtain intermediate 1. The present application does not have special provisions for the method of removing the organic solvent, and the solvent can be separated from the reaction system by the method well known to those skilled in the art, which can be rotary evaporation. In the present application, the chromatographic separation is preferably column chromatographic separation. The present application does not have special provisions for the method of column chromatographic separation, and the impurities in the crude product obtained after removing the organic solvent can be separated to achieve purification by the method well known to those skilled in the art. In the examples of the present application, the packing of the column chromatographic separation is preferably SiO2; the eluent is preferably dichloromethane.

[0071] After obtaining intermediate 1, the present application mixes intermediate 1, sarcosine, a fullerene source and a second organic solvent to carry out an addition reaction to obtain intermediate 2. In the present application, the fullerene source is C 60 , C 70 , C 84 or metal-embedded fullerene, preferably C 60In the present application, the second organic solvent is preferably one or more of toluene, chlorobenzene and o-dichlorobenzene, and more preferably toluene; and the toluene is more preferably anhydrous toluene. In the present application, the second organic solvent is preferably treated to remove water and oxygen to avoid the hydrolysis of intermediate 1 and the adverse effect of oxygen on the reaction yield. The use of anhydrous toluene as the solvent in the present application is advantageous for improving the solubility of the raw materials in the solvent and facilitating the addition reaction.

[0072] In the present application, the molar ratio of intermediate 1, sarcosine and the fullerene source is preferably 0.15-0.2:0.56-0.84:0.14, and more preferably 0.16:0.7:0.14. The present application does not have special provisions for the amount of the second organic solvent, and the amount of the solvent used in the chemical reaction known to those skilled in the art can be used.

[0073] In the present application, the mixing method of intermediate 1, sarcosine, the fullerene source and the second organic solvent is preferably as follows: the fullerene source, sarcosine and the second organic solvent are mixed to obtain a third mixture; intermediate 1 and the second organic solvent are mixed to obtain an intermediate 1 solution; and the intermediate 1 solution is added dropwise to the third mixture. In the present application, the temperature for mixing intermediate 1, sarcosine, the fullerene source and the second organic solvent is preferably room temperature.

[0074] In the present application, the addition reaction is preferably Bingel reaction, carbene addition reaction, Prato addition reaction or 1,3-dipolar cycloaddition reaction, and more preferably 1,3-dipolar cycloaddition reaction. In the present application, the temperature for the addition reaction is preferably 100-120°C, and more preferably under reflux conditions. For example, when the second organic solvent is toluene, the temperature for the addition reaction is preferably 110°C. The present application does not have special provisions for the time for the addition reaction, and the time can be monitored by using the thin layer chromatography known to those skilled in the art. In the examples of the present application, the time for the addition reaction is preferably 12-16h, and more preferably 14h; and the addition reaction is preferably carried out under an inert gas atmosphere. In the present application, the addition reaction is carried out by the dehydration reaction of sarcosine and substituted formaldehyde (i.e. intermediate 1) to produce a methine iminium inner salt, which can undergo 1,3-dipolar cycloaddition with the 6,6-bond in the fullerene source to obtain the corresponding substituted pyrrolidinyl fullerene. When the fullerene source is C 60 , the principle is shown in formula VI:

[0075]

[0076] After the addition reaction is completed, the product of the addition reaction is preferably subjected to organic solvent removal and chromatographic separation to obtain intermediate 2. In this invention, the method of organic solvent removal is preferably the same as that used after the esterification reaction, and will not be repeated here. In this invention, the chromatographic separation is preferably column chromatography. This invention does not specify a particular method for column chromatography; any column chromatography method well-known to those skilled in the art can be used to separate impurities from the crude product obtained after organic solvent removal to achieve purification. In the embodiments of this invention, the packing material for column chromatography is preferably SiO2; the eluent is preferably toluene.

[0077] After obtaining intermediate 2, the present invention mixes intermediate 2, compound 2, and a third organic solvent to perform a quaternization reaction to obtain the fullerene derivative. In the present invention, the third organic solvent is preferably one or more of toluene, chlorobenzene, and o-dichlorobenzene, more preferably o-dichlorobenzene. In the present invention, compound 2 is preferably CH3F, CH3Br, or CH3I, more preferably CH3I.

[0078] In this invention, the molar ratio of intermediate 2 to compound 2 is preferably 1:4000-4800. This invention does not specify the amount of the third organic solvent; any solvent amount known to those skilled in the art for use in chemical reactions may be used.

[0079] In this invention, the temperature of the quaternization reaction is preferably 25–75°C, more preferably 40°C; the time is preferably 5–10 days, more preferably 6–7 days; and the quaternization reaction is preferably carried out under a protective inert atmosphere. By limiting the temperature and time of the quaternization reaction to the above ranges, this invention facilitates the smooth progress of the quaternization reaction and simultaneously improves the product yield.

[0080] After the quaternization reaction is completed, the present invention preferably performs solid-liquid separation of the product of the quaternization reaction, and washes the solid phase after solid-liquid separation to obtain the fullerene derivative. In the present invention, the washing reagents preferably used are CS2, CHCl3 and MeOH in sequence.

[0081] This invention provides the application of the fullerene derivatives described in the above technical solutions or the fullerene derivatives prepared by the preparation methods described in the above technical solutions in tin-based perovskite solar cells.

[0082] This invention provides a tin-based perovskite solar cell, comprising an ITO conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a hole blocking layer, and a metal electrode stacked sequentially; the perovskite active layer is doped with the fullerene derivative described in the above-mentioned technical solution. In this invention, the tin-based perovskite solar cell is preferably an inverted planar structure.

[0083] The tin-based perovskite solar cell described in this invention includes an ITO conductive substrate. Preferably, the ITO conductive substrate comprises a polyester resin (PET) / ITO conductive substrate or a glass / ITO conductive substrate. Specifically, when using the PET / ITO conductive substrate, the resulting tin-based perovskite solar cell is a flexible tin-based perovskite solar cell; when using the glass / ITO conductive substrate, the resulting tin-based perovskite solar cell is a rigid tin-based perovskite solar cell. This invention does not specify the source of the ITO conductive substrate; any ITO conductive substrate known to those skilled in the art for preparing solar cells can be used. This invention also preferably involves cleaning the ITO conductive substrate. Preferably, the cleaning process includes: sequential ultrasonic cleaning with deionized water, isopropanol, acetone, and ethanol, followed by ultraviolet ozone cleaning to obtain a pretreated ITO conductive substrate. Preferably, the ultrasonic cleaning time for each reagent is 10–20 min; the ultraviolet ozone cleaning time is preferably 15–30 min.

[0084] The tin-based perovskite solar cell of this invention includes a hole transport layer stacked on one side of the ITO conductive substrate. In this invention, the raw material for the hole transport layer is preferably poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS). Using PEDOT:PSS as the raw material for the hole transport layer in this invention results in a perovskite solar cell with a high photoelectric conversion efficiency in its inverted planar structure. This invention does not specify a particular method for preparing the hole transport layer; any method well-known to those skilled in the art can be used. In the embodiments of this invention, spin-coating is preferred for preparing the hole transport layer.

[0085] The tin-based perovskite solar cell of this invention includes a perovskite active layer stacked on the surface of the hole transport layer. In this invention, the perovskite active layer preferably comprises the following raw materials: fullerene derivatives, stannous iodide, phenylethylamine iodide, formamidinic acid, methylamine iodide, stannous fluoride, and ammonium thiocyanate; the fullerene derivative is the fullerene derivative described in the above technical solution.

[0086] In this invention, the preferred method for preparing the perovskite active layer includes: mixing and dissolving a fullerene derivative with stannous iodide, phenylethylamine iodide, formamidinic acid, methylaminoiodic acid, stannous fluoride, and ammonium thiocyanate to obtain a perovskite active solution; and spin-coating the perovskite active solution onto the surface of the hole transport layer to obtain the perovskite active layer. In this invention, the preferred mass ratio of the fullerene derivative, stannous iodide, phenylethylamine iodide, formamidinic acid, methylaminoiodic acid, stannous fluoride, and ammonium thiocyanate is 0.4–0.5:332.5:33.6–36:127.6–131.6:10:14:6. In this invention, the perovskite active solution is preferably filtered before spin-coating. In this invention, the filter mesh size is preferably 0.1–0.22 μm.

[0087] In this invention, the mass of the fullerene derivative in the perovskite active layer is preferably 0.2-3% of the total mass of stannous iodide, phenethylamine iodide, and formamidinic hydroiodic acid, more preferably 0.4-0.5%.

[0088] The tin-based perovskite solar cell of this invention includes an electron transport layer stacked on the surface of the perovskite active layer. In this invention, the electron transport layer is preferably formed by spin-coating [6,6]phenyl-C61-butyrate isomethyl ester (PCBM) dissolved in chlorobenzene. In this invention, the solid-liquid ratio of [6,6]phenyl-C61-butyrate isomethyl ester to chlorobenzene is preferably 10–30:1 mg / mL, more preferably 20:1 mg / mL.

[0089] The tin-based perovskite solar cell of this invention includes a hole-blocking layer stacked on the surface of the electron transport layer. In this invention, the hole-blocking layer is preferably formed by spin-coating 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) dissolved in isopropanol. In this invention, the solid-liquid ratio of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline to isopropanol is preferably 0.5–2:1 mg / mL, more preferably 1:1 mg / mL.

[0090] The tin-based perovskite solar cell of this invention includes electrodes stacked on the surface of the hole-blocking layer. In this invention, the electrodes are preferably silver electrodes. In this invention, the thickness of the silver electrodes is preferably 80–100 nm. In this invention, the silver electrodes are preferably prepared by thermal evaporation deposition, wherein the thermal evaporation deposition temperature is preferably 50–65 °C and the pressure is preferably 5.5 × 10⁻⁶. -4 Pa.

[0091] The present invention does not impose any special limitations on the spin coating method and conditions; any method and conditions known to those skilled in the art can be used.

[0092] In this invention, when preparing the hole transport layer, perovskite active layer, electron transport layer, and hole blocking layer, annealing is preferably performed after spin coating. In this invention, the annealing temperature is preferably 30–150°C, more preferably 70°C; the annealing time is preferably 3–15 min, more preferably 10 min.

[0093] To further illustrate the present invention, the fullerene derivatives 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.

[0094] Example 1

[0095] The fullerene derivative FTAI was prepared with the following chemical structural formula:

[0096]

[0097] The reaction formula for preparing the fullerene derivative FTAI is as follows:

[0098]

[0099] The specific preparation method of intermediate C1 is as follows:

[0100] 2 mol of lipoic acid and 2.25 mol of 4-hydroxybenzaldehyde were dissolved in 20 mL of anhydrous tetrahydrofuran to obtain a first mixture. 1.6 mol of 4-dimethylaminopyridine and 2.25 mol of dicyclohexylcarbodiimide were dissolved in 3–5 mL of anhydrous tetrahydrofuran to obtain a transparent second mixture. The first mixture was cooled to 0 °C in an ice bath under stirring, and then the second mixture was added dropwise. After the addition was complete, the mixture was stirred at 0 °C for 30 min, and then heated to room temperature for esterification for 2 days. After the reaction was completed, the obtained esterification product system was filtered to remove the solids, and the filtrate was vacuum distilled to remove the solvent. The residue was separated and purified by column chromatography (SiO2 as packing material, dichloromethane as eluent) to obtain a yellow oily substance (4-(acyloxy)benzaldehyde), denoted as intermediate C1, with a yield of 48%.

[0101] The specific preparation method of intermediate FTA is as follows:

[0102] 0.14 mmol C 600.7 mmol of sarcosine was dissolved in 35 mL of anhydrous toluene to obtain a third mixture. 0.16 mmol of 4-(acyloxy)benzaldehyde was dissolved in 5 mL of anhydrous toluene to obtain an intermediate solution. The above intermediate solution was added dropwise to the above third mixture. After the addition was complete, the temperature was raised to 110 °C, and the addition reaction was carried out for 14 h in the presence of argon. After the reaction was completed, the obtained product system was cooled to room temperature and the solvent was evaporated. The residue was separated and purified by column chromatography (SiO2 as packing material, dichloromethane as eluent). The crude product was precipitated with methanol, and after solid-liquid separation, a brown solid intermediate FTA was obtained. The yield of intermediate FTA was 35%.

[0103] The specific preparation method of the fullerene derivative FTAI is as follows:

[0104] 0.1 mmol of intermediate FTA was dissolved in 25 mL of o-dichlorobenzene (o-DCB) and mixed with 25 mL of iodomethane to obtain a mixed system. The mixed system was heated to 40 °C and subjected to quaternization reaction for 7 days under an argon atmosphere and stirring. After the reaction was completed, the obtained product system was subjected to solid-liquid separation to obtain a brown precipitate. The brown precipitate was washed sequentially with CS2, CHCl3 and MeOH until the washing solution was colorless and clear to obtain the fullerene derivative FTAI with a yield of 85%.

[0105] Application Example 1

[0106] The specific steps for fabricating a tin-based perovskite solar cell with a structure of glass / ITO / PEDOT:PSS / perovskite / PCBM / BCP / silver are as follows:

[0107] Cleaning the glass / ITO substrate: The glass / ITO substrate was ultrasonically cleaned for 20 minutes each with deionized water, isopropanol, acetone and ethanol, and then cleaned with ultraviolet ozone for 30 minutes to obtain the pretreated glass / ITO substrate.

[0108] Spin-coated hole transport layer: Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT:PSS) was spin-coated onto the surface of a pretreated glass / ITO substrate. After spin-coating, the substrate was annealed at 150°C for 15 min to obtain a hole transport layer with a thickness of 50 nm on the surface of the glass / ITO substrate.

[0109] Preparation of the perovskite active layer: Weigh 332.5 mg stannous iodide, 33.6 mg phenethylamine iodide, 131.6 mg formamidinic acid, 10 mg methylaminohydriodic acid, 14 mg stannous fluoride, 6 mg ammonium thiocyanate, and 0.5 mg fullerene derivative FTAI, and dissolve them in 800 μL DMF and 200 μL DMF. A perovskite active solution was obtained by stirring a DMSO mixed polar solution at 50°C for 30 min. The perovskite active solution was then filtered through a polytetrafluoroethylene filter with a pore size of 0.22 μm to obtain a perovskite spin-coating solution. 50 μL of the perovskite spin-coating solution was dropped onto the hole transport layer. At the 30s of spin coating, 600 μL of anhydrous toluene was pipetted onto the spin-coated hole transport layer. After the perovskite spin-coating solution and anhydrous toluene were completely added, the spin-coated substrate was annealed at 30°C for 3 min, and then transferred to a 70°C hot plate for annealing for 10 min. A perovskite active layer was obtained by stacking the perovskite active layer on the hole transport layer. The mass content of FTAI in the perovskite active layer was 0.5 wt%, which is the mass fraction of FTAI in 0.5 mg of FTAI in 335.2 mg of stannous iodide, 33.6 mg of phenethylamine iodide, and 131.6 mg of formamidinium hydroiodic acid.

[0110] Preparation of electron transport layer: 20 mg of [6,6]phenyl-C61-butyric acid isomethyl ester (PCBM) was dissolved in 1 mL of chlorobenzene and spin-coated onto the above perovskite active layer. The spin-coated substrate was annealed at 70 °C for 10 min. An electron transport layer with a thickness of 30 nm was obtained by stacking on the perovskite active layer.

[0111] Preparation of hole blocking layer: 1 mg of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was weighed and dissolved in 1 mL of isopropanol, and then spin-coated onto the above electron transport layer. The spin-coated substrate was annealed at 70 °C for 10 min. A hole blocking layer with a thickness of 8 nm was obtained by stacking on the electron transport layer.

[0112] Electrode fabrication: at 5.5 × 10 -4 Under conditions of Pa and 55°C, a silver layer with a thickness of 80 nm was thermally evaporated and deposited on the surface of the hole blocking layer as an electrode to obtain a tin-based perovskite solar cell, denoted as FTAI-1. The structure of the tin-based perovskite solar cell is as follows: Figure 3 As shown.

[0113] Application Example 2

[0114] A tin-based perovskite solar cell with a structure of PET / ITO / PEDOT:PSS / perovskite / PCBM / BCP / silver was prepared according to the preparation method described in Application Example 1. It is denoted as FTAI-2, with the only difference being that the substrate is a PET / ITO substrate.

[0115] Comparative Example 1

[0116] A tin-based perovskite solar cell with a structure of glass / ITO / PEDOT:PSS / perovskite / PCBM / BCP / silver was prepared according to the preparation method described in Application Example 1. The only difference was that FTAI was not doped in the preparation of the perovskite active layer, which was denoted as Control-1.

[0117] Comparative Example 2

[0118] A tin-based perovskite solar cell with a structure of PET / ITO / PEDOT:PSS / perovskite / PCBM / BCP / silver was prepared according to the preparation method described in Application Example 1, the only difference being that the substrate is a PET / ITO substrate, and FTAI is not doped in the preparation of the perovskite active layer, denoted as Control-2. The structure of the tin-based perovskite solar cell is as follows. Figure 4 As shown.

[0119] Test case

[0120] The intermediate C1, intermediate FTA, and fullerene derivative FTAI prepared in Example 1 were characterized by NMR. The NMR characterization data of intermediate C1 are as follows:

[0121] 1 H-NMR (500MHz, CDCl3): δ (ppm) 9.98 (s, 1H), 7.90, 7.25 (d, 2H), 3.64-3.54 (m, 1H), 3.21-3.06 (m ,2H),2.60(t,2H),2.53-2.41(m,1H),1.97-1.85(m,1H),1.82-1.70(m,4H),1.62-1.51(m,2H). 13 C-NMR (125MHz, CDCl3): δ (ppm) 191.00, 171.34, 155.46, 134.04, 131.30, 122.43, 56.35, 40.34, 38.61, 34.66, 34.22, 28.65, 24.59.;

[0122] The NMR characterization data of the intermediate FTA are as follows:

[0123] 1 H-NMR (500MHz, CDCl3): δ (ppm) 7.16 (m, 4H), 5.00 (d, 2H), 4.96 (s, 1H), 4.29 (d, 2H), 3.57 (m ,2H),3.20-3.10(m,2H),2.83(s,3H),2.57(t,2H),2.49(m,2H),1.96(m,1H),1.76(m,2H).13 C-NMR (125MHz, CDCl3): δ (ppm) 170.89, 156.01, 153.78, 153.12, 152.90, 150.77, 147.26, 146.55, 146.29, 146.19, 146.11,146.01,145.91,145.57,145.53,145.46,145.35,145.29,145.25,144.68,144.59,144.36,144.34,142.24 ,142.21,142.14,142.12,142.07,142.02,141.98,141.86,141.85,141.67,141.54,140.21,140.18,139.96,139.5 7,121.79,82.90,69.99,68.87,56.38,40.36,39.98,38.77,34.82,34.22,28.93,24.84.MS(APCI):m / z=1057.0[M] － .

[0124] The NMR characterization data of the fullerene derivative FTAI are as follows:

[0125] 1 H-NMR (500MHz, CDCl3): δ (ppm) 7.43 (m, 4H), 7.26 (d, 2H), 7.24 (s, 1H), 6.03 (d, 2H), 5.75 (m, 2H), 5.14-5.04(m,2H),4.21(s,3H),3.64(s,3H),2.88(t,2H),2.64(m,2H),2.08(m,1H),1.99(m,2H). 13C-NMR (125MHz, CDCl3): δ (ppm) 170.99, 153.56, 153.38, 149.70, 147.46, 147.29, 146.49, 146.30, 146.16, 145.89, 145. 84,145.75,145.69,145.60,145.53,145.47,145.28,145.24,144.99,144.74,144.50,144.38,143.39,143.20,143.01 ,142.91,142.85,142.81,142.63,142.36,142.21,141.95,141.77,141.48,141.43,141.32,140.44,140.00,139.81,1 23.62,83.85,77.31,73.27,69.61,67.83,52.89,46.98,34.25,33.73,31.78,26.51,24.95. MS (ESI): m / z=1072.1402.

[0126] The fullerene derivative FTAI prepared in Example 1 was characterized by mass spectrometry, and the results are as follows: Figure 1 As shown.

[0127] Figure 1 This is the mass spectrum of the fullerene derivative FTAI, from... Figure 1 Based on the NMR characterization data, it can be seen that the theoretical molecular weight of the fullerene derivative FTAI prepared in this invention is consistent with the measured value. The results of the proton NMR spectrum and mass spectrometry complement each other to show that the chemical structure of FTAI is correct.

[0128] The fullerene derivative FTAI prepared in Example 1 was heated to 70°C, and the fullerene derivative FTAI before and after heating was characterized by ultraviolet-visible light. The results are as follows. Figure 2 As shown.

[0129] Figure 2 The images show the UV-Vis spectra of the fullerene derivative FTAI before and after heating. Figure 2 The results show that after heating to 70°C, the characteristic peaks of dithiocyclopentane in FTAI at 320–350 nm are significantly weakened. This indicates that at lower annealing temperatures, the dithiocyclopentane group in FTAI can open the ring and self-crosslink to form fullerene polymers.

[0130] Test Example 2

[0131] The photoelectric conversion efficiency of the tin-based perovskite solar cells described in Examples 1-2 and Comparative Examples 1-2 was tested, and the results are shown in the figure below.

[0132] Figure 5 The JV curves of the tin-based perovskite solar cells described in Application Example 1 and Comparative Example 1 are shown below; Figure 5 The results show that the perovskite solar cell prepared using Example 1 exhibits superior photoelectric conversion efficiency. This is because the polymerizable fullerene derivative doped into the perovskite layer contains abundant functional groups (carbonyl groups, ring-opening disulfide bonds), which can coordinate with divalent tin ions. The interaction between FTAI and perovskite promotes slow growth of the perovskite crystals. Furthermore, the polymer is applied to the perovskite mesophase before the perovskite film undergoes 70°C hot annealing. This treatment significantly reduces the organic cations (FACs) at the A-site of the surface perovskite during hot annealing. + MA + The loss of FTAI (sulfuric acid) is reduced. Furthermore, iodine ions in FTAI can fill iodine vacancies in perovskite, improving the stability of perovskite photovoltaic devices.

[0133] Figure 6 To illustrate the JV curves of the tin-based perovskite solar cells described in Application Example 2 and Comparative Example 2, from... Figure 6 The results show that the perovskite film exhibits a non-uniform residual stress distribution, with more severe lattice tensile strain in the top perovskite film region, which is detrimental to carrier transport at the perovskite interface and within the film, and is more pronounced in flexible devices. Doping the perovskite layer with FTAI can not only form a polymer through ring-opening of dithiocyclopentane, establishing a polymer network to reduce residual stress within the perovskite and improve the mechanical stability of flexible devices, but also, the superior conductivity of FTAI distributed at the grain boundaries itself is more conducive to carrier transport at the grain boundaries and interfaces, thereby improving the photoelectric conversion efficiency of flexible perovskites.

[0134] Figure 7 The graph shows the photoelectric conversion efficiency statistics of the tin-based perovskite solar cells described in Examples 1-2 and Comparative Examples 1-2, by... Figure 7 The results show that for rigid substrate devices, the highest photoelectric conversion efficiency of Control-1 is 10.52%, and that of FTAI-1 is 14.68%, which is similar to the highest photoelectric conversion efficiency of 14.81% reported for rigid substrate tin-based perovskite solar cells. For flexible substrate devices, the highest photoelectric conversion efficiency of Control-2 is 7.04%, and that of FTAI-2 is 9.22%, which is much higher than the 8.56% reported for flexible tin-based perovskite solar cells.

[0135] In summary, the fullerene derivatives prepared in this invention have the characteristic of being cross-linked to form polymers. This not only releases residual stress inside the perovskite and improves the mechanical stability of the perovskite on both rigid and flexible substrates, but the introduction of fullerenes can also enhance the transport of charge carriers inside and at the interface of the perovskite, enabling flexible tin-based perovskite solar cells to achieve excellent photoelectric conversion efficiency.

[0136] 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 derivative having the structure shown in Formula I: In formula I, X - It is a halide ion or a pseudohalogen ion; the halide ion is F. - Cl - ,Br - I - The pseudohalogen ion is SCN. - or CN - ; R is a dithionylcyclopentyl group; Fu is C 60 C 70 C 84 Or it may contain embedded metallofullerenes.

2. The fullerene derivative according to claim 1, characterized in that, The dithiohexacyclopentyl group has the following structure:

3. A method for preparing the fullerene derivative according to claim 1 or 2, comprising the following steps: Compound 1, 4-hydroxybenzaldehyde, catalyst and first organic solvent were mixed and esterified to obtain intermediate 1. The intermediate 1 has the following chemical structure: Intermediate 1, sarcosine, fullerene source, and a second organic solvent are mixed and subjected to an addition reaction to obtain intermediate 2; the fullerene source is C2. 60 C 70 C 84 Or embedded metallofullerene; The intermediate 2, compound 2 and the third organic solvent were mixed and quaternized to obtain the fullerene derivative having the structure shown in Formula I. When the fullerene source is C 60 At that time, the intermediate 2 has the following chemical structure: Compound 1 has the structure shown in Formula II: In equation II, R is as defined in equation I; The chemical formula of compound 2 is CH3X; X is as defined in formula I.

4. The preparation method according to claim 3, characterized in that, The catalyst comprises 4-dimethylaminopyridine and / or dicyclohexylcarbodiimide.

5. The preparation method according to claim 3, characterized in that, The first organic solvent is tetrahydrofuran; the second and third organic solvents are independently one or more of toluene, chlorobenzene and o-dichlorobenzene.

6. The use of the fullerene derivative of claim 1 or 2 in tin-based perovskite solar cells.

7. A tin-based perovskite solar cell, comprising a conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a hole blocking layer, and a metal electrode stacked sequentially; wherein the perovskite active layer is doped with the fullerene derivative of claim 1 or 2.

8. The tin-based perovskite solar cell according to claim 7, characterized in that, The perovskite active layer comprises the following raw materials: fullerene derivatives, stannous iodide, phenethylamine iodide, formamidinic hydroiodic acid, methylamine hydroiodic acid, stannous fluoride, and ammonium thiocyanate.

9. The tin-based perovskite solar cell according to claim 8, characterized in that, The mass of the fullerene derivative in the perovskite active layer is 0.2-3% of the total mass of stannous iodide, phenethylamine iodide, and formamidinic hydroiodic acid.

Images