Fullerene C60 tetra-addition derivative as well as preparation method and application thereof

Abstract

The invention discloses a fullerene C60 tetra-addition derivative as well as a preparation method and application thereof. The structure of the fullerene C60 tetra-addition derivative is shown as a formula I. The specific preparation method comprises the following steps: under the protection of inert gas, taking fullerene C60, tetrabutyl ammonium hydroxide hydrate, benzyl bromide and a TBAOH methanol solution as raw materials, taking o-dichlorobenzene or methylbenzene as a solvent, and reacting at 60-80 DEG C to obtain the target fullerene C60 tetra-addition derivative. The preparation method of the fullerene C60 tetra-addition derivative has the advantages of simple operation steps, safety, easiness in control, high selectivity and the like. A photovoltaic device prepared by using the fullerene derivative as an acceptor material has high open-circuit voltage, and is a very potential photovoltaic material. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of fullerene derivatives, and particularly relates to a fullerene C 60 Tetra-addition derivatives and preparation methods and applications thereof. The fullerene derivatives can be used as receptor materials in the field of organic solar cells. Background Art

[0002] Fullerene, as a hollow molecule composed entirely of carbon, has a unique zero-dimensional structure and a conjugated π electron system. Functionalization of the carbon skeleton of fullerenes by introducing various functional groups has become an important research direction in the field of fullerene chemistry. At present, many fullerene derivatives have been successfully synthesized and widely used in materials science, drug development, electronic devices, and energy storage. These derivatives not only inherit the excellent properties of the fullerene family, such as excellent electron mobility and unique chemical reactivity, but also introduce new functions through chemical modification, such as enhanced solubility, improved biocompatibility, and specific spectral characteristics. Among them, the monoaddition fullerene C 60 Derivatives [6,6]-phenyl-C 61 -Butyric acid methyl ester (PCBM) is used as an acceptor material and blended with the donor material poly-3-hexylthiophene (P3HT) to construct organic solar cells (OSCs) photovoltaic devices, which can effectively promote the separation and transmission of photogenerated charges and play a key role in photovoltaic devices.

[0003] Fullerene C 60 Tetra-addition derivatives belong to a class of fullerene derivatives with special structures and properties. Compared with the single addition fullerene C 60 Derivatives, these derivatives introduce four addition groups on the four carbon atoms of the fullerene carbon cage, thus forming new compounds. These derivatives retain the fullerene C 60 The parent has many excellent properties, such as higher electron mobility. In addition, compared with the mono-addition derivative PCBM, the tetra-addition derivative exhibits a higher LUMO (lowest unoccupied molecular orbital) energy level due to the reduction of the number of conjugated π electrons. The increase in LUMO energy level helps to increase the open circuit voltage of photovoltaic devices, thereby enhancing the energy conversion efficiency of solar cells.

[0004] Fullerene C 60The tetraaddition derivatives can be prepared by a variety of chemical reactions, such as the Prato reaction, the Bingel reaction, etc. By introducing addition groups, the solubility, electronic properties and energy level distribution of fullerenes can be adjusted to meet the needs of different applications. However, it is still a challenge to achieve regioselective control of tetraaddition products. In the process of synthesizing these tetraaddition derivatives, the following difficulties are generally faced: complex operating steps, harsh reaction conditions, the existence of multiple regioisomers in the obtained products, and difficulty in separating and purifying the products. In addition, when these regioisomer mixtures are used as acceptor materials for organic solar cells, their disordered stacking will lead to a reduction in the number of charge carriers reaching the electrode, thereby reducing the charge extraction and transfer efficiency inside the battery. This phenomenon will lead to a decrease in short-circuit current density and fill factor, which will have an adverse effect on the performance of organic solar cells.

[0005] Therefore, it is necessary to develop a fullerene C with high selectivity and ease of operation. 60 The preparation method of tetraaddition derivatives is crucial. By introducing appropriate modifying groups through this method, the selectivity of the reaction can be improved, which is conducive to separation and purification, and thus a pure and single-structured fullerene C can be obtained. 60 Tetra-addition derivatives. This fullerene C 60 Tetraaddition derivatives have higher LUMO energy levels and can effectively increase the open circuit voltage of photovoltaic devices as acceptor materials, which is expected to improve the photoelectric performance of organic solar cells. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a fullerene C 60 Tetra-addition derivatives and preparation methods and applications thereof. The derivative preparation method has the advantages of simple operation steps, safety, easy control, high selectivity, etc. 60 Organic solar cell devices constructed with tetraaddition derivatives as acceptor materials have higher open circuit voltage and exhibit good photovoltaic performance.

[0007] To achieve the above object, the first aspect of the present invention is to provide a fullerene C 60 Tetra-addition derivatives, the fullerene C 60 The structural formula of the tetraaddition derivative is shown in Formula I.

[0008]

[0009] The second aspect of the present invention is to provide a fullerene C 60 The preparation method of the tetraaddition derivative comprises the following preparation steps:

[0010] Step 1: Under the protection of inert gas, add fullerene C 60, organic solvent, tetrabutylammonium hydroxide hydrate, stirring and reacting at a certain temperature for 0.5 to 1 hour;

[0011] Step 2: Based on the step 1, add benzyl bromide into the round-bottom flask and react for 0.5 to 1 hour;

[0012] Step 3: Based on the step 2, continue to add TBAOH methanol solution into the round-bottom flask, react for 0.5 to 1 hour, and after the reaction is completed, evaporate the solvent to obtain a crude product after elution and drying;

[0013] Step 4: Separate and purify the crude product obtained in step 3 by high performance liquid chromatography to obtain the target fullerene C 60 Tetra-addition derivatives.

[0014] In the technical solution of the present invention, the chemical reaction that occurs is as shown in Formula II.

[0015]

[0016] In the technical solution of the present invention, step 1: under the protection of inert gas, add fullerene C 60 , organic solvent, tetrabutylammonium hydroxide hydrate, stir and react at a certain temperature for 0.5 to 1 hour. Adding tetrabutylammonium hydroxide hydrate to participate in the reaction helps to generate C 60 Negative ions, increase fullerene C 60 Reaction activity; Step 2: Based on step 1, add benzyl bromide to the round-bottom flask and react for 0.5 to 1 hour. In this step, benzyl bromide acts as an electrophilic reagent and reacts with C 60 negative ions react; Step 3: Based on step 2, continue to add TBAOH methanol solution to the round-bottom flask, react for 0.5 to 1 hour, and after the reaction is completed, evaporate the solvent, then elute and dry to finally obtain a crude product. In this step, the use of TBAOH methanol solution is to provide methoxyl anions for nucleophilic reaction to prepare the target fullerene derivative; Step 4: The crude product obtained in step 3 is separated and purified by high performance liquid chromatography to obtain the target fullerene C 60 Tetra-addition derivatives. High-performance liquid chromatography (HPLC) can achieve efficient separation, thereby ensuring that the obtained fullerene derivatives have extremely high purity.

[0017] Preferably, the fullerene C 60 The molar ratio of tetrabutylammonium hydroxide hydrate, benzyl bromide and TBAOH methanol solution is 1:3-5:10-20:2-4.

[0018] In the technical solution of the present invention, the fullerene C60 The molar ratio of tetrabutylammonium hydroxide hydrate, benzyl bromide, and TBAOH methanol solution is 1:3-5:10-20:2-4. Within this ratio range, each reaction component can fully react, thereby achieving a higher yield and effectively avoiding the waste of drugs. If the molar ratio of the reactants is lower than this range, the reaction may not be complete; if the molar ratio is higher than this range, it may lead to excessive consumption of drugs, resulting in unnecessary waste.

[0019] Preferably, the tetrabutylammonium hydroxide hydrate is TBAOH·30H2O.

[0020] In the technical solution of the present invention, the tetrabutylammonium hydroxide hydrate is TBAOH·30H2O, which helps to generate C 60 Negative ions, increase fullerene C 60 Reactivity.

[0021] Preferably, the inert gas is Ar or N2.

[0022] In the technical solution of the present invention, the inert gas in step 1 is Ar or N2, which can effectively block the interference of air and avoid C 60 Negative ions are oxidized by oxygen in the air, providing protection for the reaction system and promoting the efficient and stable progress of the reaction.

[0023] Preferably, the organic solvent is o-dichlorobenzene or toluene.

[0024] In the technical solution of the present invention, the organic solvent in step 1 is o-dichlorobenzene or toluene. First, o-dichlorobenzene and toluene are both effective for fullerene C 60 They exhibit high solubility. Secondly, both solvents have good chemical and thermal stability, which helps to ensure the safety and stability of the overall reaction.

[0025] Preferably, the concentration of the TBAOH methanol solution is 0.5-1.5 mol / L.

[0026] In the technical solution of the present invention, tetrabutylammonium hydroxide (TBAOH) reacts with methanol in a methanol solution to generate methoxyl anions. The anions then react with C 60 Nucleophilic reaction occurs, and it is added to the fullerene carbon cage as a modification group. The reaction activity of TBAOH methanol solution is best in the range of 0.5-1.5 mol / L. A concentration lower than 0.5 mol / L will reduce the reaction rate, while a concentration higher than 1.5 mol / L may cause TBAOH to precipitate, which is not conducive to controlling the reaction conditions.

[0027] Preferably, the reaction temperature is 60-80°C.

[0028] In the technical solution of the present invention, the reaction temperature is 60-80°C. Mild reaction conditions are conducive to the stability of the entire reaction process and are beneficial to the target fullerene C 60 Formation of tetraaddition derivatives.

[0029] Preferably, the high performance liquid chromatography method uses a pyrenepropyl bonded silica gel chromatography column (Buckyprep) as a separation column and toluene as a mobile phase, and separates and purifies by a high performance liquid chromatograph to obtain a pure product.

[0030] In the technical solution of the present invention, the purification technology used is high performance liquid chromatography (HPLC), and the specific operation is as follows: Buckyprep is selected as a separation column, toluene is used as a mobile phase, the crude product is dissolved in toluene, and separated and purified by a high performance liquid chromatograph to obtain a pure product. This technology can achieve an excellent purification effect.

[0031] The third aspect of the present invention is to provide the fullerene C 60 The application of tetraaddition derivatives as acceptor materials in the preparation of photovoltaic devices in the field of organic solar cells.

[0032] The specific steps are:

[0033] S1: Poly-3-hexylthiophene (P3HT) is used as the donor material, and the fullerene C prepared in the present invention is used as the donor material. 60 The tetraaddition derivative is used as an acceptor material, and the donor material and the acceptor material are dissolved in an organic solvent according to a certain mass ratio, and stirred to obtain a mixed solution;

[0034] S2: On the conductive glass (ITO) after ultrasonic cleaning and ultraviolet ozone cleaning machine (UVO) cleaning, a layer of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (PEDOT / PSS) was spin-coated at 3000 rpm with a thickness of 30 nm, and then dried at 150 ° C for 10 min;

[0035] S3: spin-coat the mixed solution obtained in S1 on PEDOT / PSS, and anneal at 150°C for 10 min to obtain an annealed film;

[0036] S4: vacuum evaporating a cathode modification layer and an electrode on the thin film obtained in S3 to prepare a photovoltaic device.

[0037] In the above process S1, the mass ratio of the donor material to the acceptor material is 1:0.5-1, the organic solvent is selected from one of o-dichlorobenzene and chlorobenzene, and the concentration of the mixed solution is 20 mg / mL.

[0038] In the above process S3, the spin coating speed is 1000-2500 rpm, and the spin coating time is 30 s.

[0039] In the above process S4, the cathode modification layer material is selected from one of lithium fluoride, calcium and magnesium, and the electrode is selected from one of silver and aluminum.

[0040] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0041] (1) The present invention provides a method for synthesizing fullerene C 60 The method of tetraaddition derivatives is highly selective, making the purity and yield of the target product higher. Through this highly selective synthesis method, the subsequent separation and purification process can be simplified, thereby reducing production costs.

[0042] (2) The fullerene C of the present invention 60 Mild reaction conditions are used in the synthesis of tetraaddition derivatives, thereby improving the safety of operation and reducing the requirements for equipment performance. The use of a simple and efficient preparation method helps to simplify the complexity of the production process, and its simple process flow is suitable for large-scale production.

[0043] (3) The fullerene C of the present invention 60 The tetraaddition derivative can be used as an acceptor material for organic solar cells. Compared with the widely used PCBM, the fullerene derivative exhibits a higher open circuit voltage as an acceptor material in photovoltaic devices. 60 Tetraaddition derivatives have excellent solubility and high electron mobility. In addition to being suitable for traditional organic solar cells, they are expected to be used in new optoelectronic devices such as field-effect transistors and organic photoconductors. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Fullerene C 60 Schematic diagram of the molecular structure of tetraaddition derivatives

[0045] Figure 2 Fullerene C 60 Tetra-addition derivatives 1 H NMR spectrum

[0046] Figure 3 Fullerene C 60 Tetra-addition derivatives 13 C NMR spectrum

[0047] Figure 4 Fullerene C 60 UV-visible absorption spectrum of tetraaddition derivatives

[0048] Figure 5 Fullerene C 60 Cyclic voltammetry curves of tetra-addition derivatives and PCBM

[0049] Figure 6 Fullerene C 60 Molecular conformation, LUMO orbital and energy level diagram of tetraaddition derivatives and PCBM

[0050] Figure 7 Current-voltage curve of the photovoltaic device prepared in Example 5

[0051] Figure 8 Current-voltage curves of photovoltaic devices prepared in Example 6 and Comparative Example DETAILED DESCRIPTION

[0052] Unless otherwise specified, the instruments, materials, reagents, etc. used in all the following examples can be purchased from commercial channels, and the methods of using the relevant instruments, materials, reagents, etc. are carried out according to the relevant operating instructions.

[0053] The technical solution of the present invention will be further illustrated and described by examples below, with the purpose of enabling researchers in the field to better understand the technical solution of the present invention. However, the content of the present invention is not limited to the following examples, and relevant technical personnel should understand it.

[0054] In particular, in the following Examples 1 to 4, the addition of N times the molar equivalent of a drug means that the amount of the drug to be added is the amount of fullerene C added in this example. 60 N times the amount of substance.

[0055] Example 1

[0056] The specific steps are:

[0057] Under Ar protection, o-dichlorobenzene (30 mL) was first added to the round-bottom flask, followed by fullerene C 60 (50 mg) and 3 times the molar equivalent of TBAOH·30H2O (166.4 mg), heated in an oil bath at 60°C, reacted for 0.5 hours, then 10 times the molar equivalent of benzyl bromide (82.4 μL) was added to the round-bottom flask, and reacted for 1 hour; then 2 times the molar equivalent of TBAOH methanol solution (1.5 mol / L, 92.5 μL) was added, and reacted for 1 hour. After the reaction was completed, the solvent was evaporated and removed, and a crude product was obtained after elution and drying; the crude product was separated and purified by high performance liquid chromatography (HPLC) with toluene as the mobile phase using a Buckyprep separation column to obtain the target fullerene C 60 Tetra-addition derivatives.

[0058] Example 2

[0059] The specific steps are:

[0060] Under Ar protection, toluene (30 mL) was first added to the round-bottom flask, followed by fullerene C 60 (50 mg) and 5 times the molar equivalent of TBAOH·30H2O (277.3 mg), heated in an oil bath at 80°C, reacted for 0.5 hour, then 20 times the molar equivalent of benzyl bromide (164.8 μL) was added to the round-bottom flask, and reacted for 0.5 hour; then 4 times the molar equivalent of TBAOH methanol solution (0.5 mol / L, 555.1 μL) was added, and reacted for 1 hour. After the reaction was completed, the solvent was evaporated and removed, and a crude product was obtained after elution and drying; the crude product was separated and purified by high performance liquid chromatography (HPLC) with toluene as the mobile phase and a Buckyprep separation column to obtain the target fullerene C 60 Tetra-addition derivatives.

[0061] Example 3

[0062] The specific steps are:

[0063] Under N2 protection, toluene (30 mL) was first added to the round-bottom flask, followed by fullerene C 60 (50 mg) and 4 times molar equivalent of TBAOH·30H2O (221.9 mg), heated in an oil bath at 70°C, reacted for 0.5 hour, then 15 times molar equivalent of benzyl bromide (123.6 μL) was added to the round-bottom flask, reacted for 1 hour; then 3 times molar equivalent of TBAOH methanol solution (1.2 mol / L, 173.5 μL) was added, reacted for 0.5 hour, the reaction was terminated, the solvent was evaporated to remove, and the crude product was obtained after elution and drying; then the crude product was separated and purified by high performance liquid chromatography (HPLC), with toluene as the mobile phase, using a Buckyprep separation column to obtain the target fullerene C 60 Tetra-addition derivatives.

[0064] Example 4

[0065] The specific steps are:

[0066] Under N2 protection, o-dichlorobenzene (50 mL) was first added to the round-bottom flask, followed by fullerene C 60(100 mg) and 3 times the molar equivalent of TBAOH·30H2O (332.8 mg), heated in an oil bath at 80°C, reacted for 1 hour, then 10 times the molar equivalent of benzyl bromide (164.8 μL) was added to the round-bottom flask, and reacted for 1 hour; then 3 times the molar equivalent of TBAOH methanol solution (1.0 mol / L, 416.3 μL) was added, and reacted for 1 hour. After the reaction was completed, the solvent was evaporated and removed, and a crude product was obtained after elution and drying; the crude product was separated and purified by high performance liquid chromatography (HPLC) with toluene as the mobile phase and a Buckyprep separation column to obtain the target fullerene C 60 Tetra-addition derivatives.

[0067] Fullerene C 60 Tetra-addition derivatives 1 H NMR, 13 C NMR and UV-visible absorption spectrum test data. 1 H NMR(600MHz,in CS2,CDCl3 was used as the external lock solvent)δ7.54-7.51(m,2H),7.48-7.45(m,2H),7.35(dt,J=15.3,7.7Hz,4H),7.32-7.28(m,1H),7.26-7.23(m,1H),7.22(d,J=1.8Hz,1H),7.21(s ,2H),7.18(s,2H),4.67(d,J=13.4Hz,1H),4.33(d,J=12.7Hz,1H),4.20( d,J=13.4Hz,1H),3.99(s,4H),3.48-3.42(m,1H),3.31(d,J=13.2Hz,1H). like Figure 2 . 13C NMR(150MHz,CS2 / CDCl3)(all 1C unless indicated)δ160.74,160.62,154.65,152.64,150.39,149.99,149.67,149.13( 2C),148.91,148.56(2C),147.93,147.58,147.51(3C),147.19,146.97,146.76 ,146.57(2C),146.46,146.40,145.86(2C),145.62,145.46,145.44,145.38,14 5.33,145.30,145.20,145.04,144.90(2C),144.72,144.57,144.55,144.22,14 4.07,143.76,143.73,143.14,142.83,142.70,142.45,141.58,141.51,141.48 ,140.24,139.13,138.11,136.90,136.20,135.86,135.16(Ph),134.79(Ph),13 2.39(Ph),132.32(2C,Ph),131.16(2C,Ph),130.67(2C,Ph),128.57(2C,Ph),12 8.24(2C,Ph),127.73(2C,Ph),127.53(Ph),127.21(Ph),126.93(Ph),88.19(sp 3 ,C 60 -O),67.78(sp 3 ,C 60 -CH2),59.42(sp 3 ,C 60 -CH2),56.64(sp 3 ,C 60 -CH2),55.00(sp 3 ,O-CH3),47.22(sp 3 ,CH2),46.89(sp 3 ,CH2),44.78(sp 3 ,CH2). Figure 3 . UV-vis (hexane) λ max / nm: 210, 250, 296, 361, 462. Figure 4 .

[0068] Fullerene C 60Comparison of LUMO energy levels of tetraaddition derivatives and PCBM. Cyclic voltammetry curve data: Cyclic voltammetry measurements were performed in a benzonitrile (PhCN) solution containing 0.1 M tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte, using ferrocene as an internal standard, a glassy carbon electrode (GCE) as the working electrode, a platinum wire electrode (Pt) as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode, with a scan rate of 100 mV / s. Figure 5 , fullerene C 60 The first reduction half-wave potential (E 1 / 2 red1 ) is -1.21 V, and through the formula LUMO = -(4.80 + E 1 / 2 red1 )eV, the LUMO energy level is -3.59eV; under the same conditions, the first reduction half-wave potential of PCBM is -1.00V, and the LUMO energy level is -3.80eV calculated by the formula; the cyclic voltammetry test results show that fullerene C 60 The LUMO energy level of the tetraaddition derivative is higher than that of PCBM. Theoretical calculation simulation data: The calculation data of density functional theory (DFT) at the B3LYP / 6-31G(d) level are as follows Figure 6 As shown, fullerene C 60 The calculated LUMO energy level of the tetraaddition derivative is -2.90 eV, while that of PCBM is -3.09 eV. 60 The tetraaddition derivative has a higher LUMO energy level than PCBM. This theoretical calculation simulation result is consistent with the data trend obtained from the cyclic voltammetry test, which strongly confirms the potential applicability of the derivative as an electron acceptor material.

[0069] Example 5

[0070] The specific steps are:

[0071] S1: P3HT as donor material, fullerene C 60 The tetraaddition derivative is used as the acceptor material, and the donor material and the acceptor material are dissolved in o-dichlorobenzene at a mass ratio of 1:0.5, and stirred to obtain a mixed solution with a solution concentration of 20 mg / mL;

[0072] S2: On the ultrasonically cleaned and UVO treated conductive glass (ITO), a layer of PEDOT / PSS was spin-coated at 3000 rpm with a thickness of 30 nm, and then dried at 150 °C for 10 min;

[0073] S3: Spin-coat the mixed solution obtained in S1 on PEDOT / PSS at a rotation speed of 1500 rpm for 30 seconds, and then anneal at 150°C for 10 minutes to obtain an annealed film;

[0074] S4: On the thin film obtained in S3, Ca and Al are evaporated to the top layer with thicknesses of 10 nm and 150 nm respectively, to prepare a photovoltaic device.

[0075] At AM 1.5100mW / cm 2 Under the light intensity, the open circuit voltage of the photovoltaic device prepared in Example 5 is 0.79V and the short circuit current is 2.99mA / cm 2 , the fill factor is 38.48%, and the photoelectric conversion efficiency is 0.91%. The current-voltage curve of the photovoltaic device is as follows Figure 7 shown.

[0076] Example 6

[0077] The specific steps are:

[0078] S1: P3HT as donor material, fullerene C 60 The tetraaddition derivative is used as the acceptor material, and the donor material and the acceptor material are dissolved in o-dichlorobenzene at a mass ratio of 1:1, and stirred to obtain a mixed solution with a solution concentration of 20 mg / mL;

[0079] S2: On the ultrasonically cleaned and UVO treated conductive glass (ITO), a layer of PEDOT / PSS was spin-coated at 3000 rpm with a thickness of 30 nm, and then dried at 150 °C for 10 min;

[0080] S3: Spin-coat the mixed solution obtained in S1 on PEDOT / PSS at a rotation speed of 1500 rpm for 30 seconds, and then anneal at 150°C for 10 minutes to obtain an annealed film;

[0081] S4: On the thin film obtained in S3, Ca and Al are evaporated to the top layer with thicknesses of 10 nm and 150 nm respectively, to prepare a photovoltaic device.

[0082] At AM 1.5 100mW / cm 2 Under the light intensity, the open circuit voltage of the photovoltaic device prepared in Example 6 is 0.78V, and the short circuit current is 3.31mA / cm 2 , the fill factor is 41.40%, and the photoelectric conversion efficiency is 1.07%. The current-voltage curve of the photovoltaic device is as follows Figure 8 shown.

[0083] Comparative Example 1

[0084] The difference between this embodiment and embodiment 6 is that in process S3, the spin coating speed is 1000 rpm.

[0085] After testing, the open circuit voltage of the photovoltaic device prepared in Comparative Example 1 was 0.78 V and the short circuit current was 3.18 mA / cm 2 , the fill factor is 40.77%, and the photoelectric conversion efficiency is 1.01%. The current-voltage curve of the photovoltaic device is as follows Figure 8 shown.

[0086] Comparative Example 2

[0087] The difference between this embodiment and embodiment 6 is that in process S3, the spin coating speed is 2000 rpm.

[0088] After testing, the open circuit voltage of the photovoltaic device prepared in Comparative Example 2 was 0.80 V and the short circuit current was 2.95 mA / cm 2 , the fill factor is 43.40%, and the photoelectric conversion efficiency is 1.02%. The current-voltage curve of the photovoltaic device is as follows Figure 8 shown.

[0089] Comparative Example 3

[0090] The difference between this embodiment and embodiment 6 is that in process S3, the spin coating rotation speed is 2500 rpm.

[0091] After testing, the open circuit voltage of the photovoltaic device prepared in Comparative Example 3 was 0.80 V and the short circuit current was 3.02 mA / cm 2 , the fill factor is 43.73%, and the photoelectric conversion efficiency is 1.05%. The current-voltage curve of the photovoltaic device is as follows Figure 8 shown.

[0092] Result analysis: By analyzing the data of Example 6 and Comparative Examples 1 to 3, it can be found that in process S3, the relationship between the photoelectric conversion efficiency and the spin coating speed is not significant. When the spin coating speed is 1500rpm, the prepared photovoltaic device shows the highest photoelectric conversion efficiency; when the spin coating speed is increased from 1000rpm to 1500rpm, the photoelectric conversion efficiency of the prepared photovoltaic device shows a trend of increasing with the increase of the spin coating speed; when the spin coating speed exceeds 1500rpm, further increasing the spin coating speed will not increase the photoelectric conversion efficiency of the photovoltaic device.

[0093] The above-described embodiments and comparative examples are only preferred embodiments of the present invention and do not represent all possible embodiments. The protection scope of this patent covers all requirements described in the claims. Any minor non-creative changes to the experimental steps, processes and techniques involved in this patent are deemed to be within the protection scope of this patent.

Claims

1. A fullerene C 60 A tetraaddition derivative, characterized in that The fullerene C 60 The structural formula of the tetraaddition derivative is shown in Formula Ⅰ.

2. A fullerene C according to claim 1 60 The method for preparing a tetraaddition derivative is characterized in that: The method comprises the following preparation steps: Step 1: Under the protection of inert gas, add fullerene C 60 , organic solvent, tetrabutylammonium hydroxide hydrate, stirring and reacting at a certain temperature for 0.5 to 1 hour; Step 2: Based on the step 1, add benzyl bromide into the round-bottom flask and react for 0.5 to 1 hour; Step 3: Based on the step 2, continue to add TBAOH methanol solution into the round-bottom flask, react for 0.5 to 1 hour, and after the reaction is completed, evaporate the solvent to obtain a crude product after elution and drying; Step 4: Separate and purify the crude product obtained in step 3 by high performance liquid chromatography to obtain the target fullerene C 60 Tetra-addition derivatives.

3. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The fullerene C 60 The molar ratio of tetrabutylammonium hydroxide hydrate, benzyl bromide and TBAOH methanol solution is 1:3-5:10-20:2-4.

4. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The tetrabutylammonium hydroxide hydrate is TBAOH·30H2O.

5. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The inert gas is Ar or N2.

6. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The organic solvent is o-dichlorobenzene or toluene.

7. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The concentration of the TBAOH methanol solution is 0.5-1.5 mol / L.

8. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The reaction temperature is 60-80°C.

9. The fullerene C according to claim 2 60 The method for preparing a tetraaddition derivative is characterized in that: The high performance liquid chromatography method uses a pyrenepropyl bonded silica gel chromatography column (Buckyprep) as a separation column and toluene as a mobile phase, and separates and purifies the product through a high performance liquid chromatograph to obtain a pure product.

10. The fullerene C according to claim 1 60 The application of tetraaddition derivatives as acceptor materials in the preparation of photovoltaic devices in the field of solar cells.

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