CN114899322B - Fullerene di (ethoxycarbonyl) methylene derivative electron transport material, application thereof, solar cell and preparation method thereof - Google Patents

Abstract

The invention provides a fullerene di (ethoxycarbonyl) methylene derivative electron transport material and application thereof, a solar cell and a preparation method thereof, and relates to the technical field of fullerene materials and tin-based perovskite solar cells. The fullerene di (ethoxycarbonyl) methylene derivative electron transport material is obtained by separating, purifying and drying fullerene di (ethoxycarbonyl) methylene derivative to obtain four positional isomers trans-2, trans-3, trans-4 and e and reasonably blending the proportions of the four isomers. The film forming property of the electron transport material can be improved through reasonable proportion, the energy disorder caused by the change of isomer proportion is reduced, the energy level of the electron transport material is better matched with that of tin-based perovskite, the electron extraction and transport capacity of the fullerene film is enhanced, meanwhile, the energy barrier of carrier diffusion at an interface can be effectively reduced, the open circuit voltage loss is reduced, and the tin-based perovskite solar cell with high photoelectric conversion efficiency is realized.

Description

Fullerene di(ethoxycarbonyl)methylene derivative electron transport material and application, solar cell and preparation method thereof

Technical Field

The invention relates to the technical field of fullerene materials and tin-based perovskite solar cells, and in particular to a fullerene di(ethoxycarbonyl)methylene derivative electron transport material and application thereof, a solar cell and a preparation method thereof.

Background technique

In order to use solar energy to solve the energy crisis and the environmental problems caused by the burning of fossil energy, researchers have conducted extensive research on organic-inorganic hybrid halide lead-based perovskite solar cells (LPSCs). LPSCs have developed very rapidly. In just over a decade, their photoelectric conversion efficiency has increased from the initial 3.8% to the current 25.7%. But at the same time, the toxicity of lead and the Shockley-Queisser limit of lead-based perovskites are also issues that cannot be ignored and hinder their further development. In order to solve these problems, non-lead perovskite solar cells have received widespread attention in recent years. Among them, tin-based perovskites have become the most promising non-lead perovskite materials because of their narrower band gap, stronger exciton binding energy and higher absorption coefficient.

At present, there is still a significant gap in the photoelectric conversion efficiency (PCE) of tin-based perovskite solar cells (TPSCs) compared to mainstream LPSCs. One of the main reasons is that the conduction band bottom of tin-based perovskites is higher than that of lead-based perovskites, which makes the fullerene electron transport layer materials (such as C60, PCBM, etc.) commonly used in trans-LPSCs not well matched with their energy levels, leading to large open-circuit voltage losses. Indene-C60 bisadduct (ICBA), which is also a disubstituted fullerene material, has too many isomers and the isomer ratios of different batches vary greatly, which can easily cause energy disorder and affect the photoelectric conversion efficiency of the device. Fullerene di(ethoxycarbonyl)methylene derivatives are simple to synthesize, and the LUMO energy level position is higher than that of C60, PCBM, etc., so it is more compatible with the energy level of tin-based perovskites as an electron transport layer material. However, fullerene di(ethoxycarbonyl)methylene derivatives contain a series of positional isomers, and the ratio of isomers in different batches of products is different, which makes it difficult to obtain a relatively stable photoelectric conversion efficiency when fullerene di(ethoxycarbonyl)methylene derivatives composed of isomers in different ratios are used in TPSCs. Therefore, how to adjust the ratio of these isomers to obtain a higher PCE has attracted extensive attention from researchers.

Summary of the invention

The object of the present invention is to provide a fullerene di(ethoxycarbonyl)methylene derivative electron transport material. The electron transport material can reduce the difference in the ratio of fullerene isomers in different batches, reduce energy disorder, enhance electron extraction and transmission capabilities, and achieve the purpose of improving the photoelectric conversion efficiency of the corresponding tin-based perovskite solar cell by reasonably adjusting the ratio between different isomers of the fullerene di(ethoxycarbonyl)methylene derivative.

Another object of the present invention is to provide the use of the above-mentioned fullerene bis(ethoxycarbonyl)methylene derivative electron transport material in the preparation of tin-based perovskite solar cells.

The third object of the present invention is to provide a method for preparing a tin-based perovskite solar cell, which is simple and has controllable parameters and is suitable for industrial large-scale production.

The fourth object of the present invention is to provide a tin-based perovskite solar cell, which uses a fullerene bis(ethoxycarbonyl)methylene derivative electron transport material as an electron transport layer, thereby improving its photoelectric conversion efficiency.

The present invention solves the technical problem by adopting the following technical solutions.

The present invention provides a fullerene bis(ethoxycarbonyl)methylene derivative electron transport material, including isomer trans-2, isomer trans-3, isomer trans-4 and isomer e, wherein the molecular structures of the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e are respectively:

Among them, in terms of mass percentage, in the fullerene di(ethoxycarbonyl)methylene derivative electron transport material, the mass percentage of the isomer trans-2 is 10% to 30%, the mass percentage of the isomer trans-3 is 25% to 40%, the mass percentage of the isomer trans-4 is 5% to 10%, and the mass percentage of the isomer e is 20% to 60%.

The present invention proposes the use of the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material in the preparation of tin-based perovskite solar cells.

The present invention provides a method for preparing a tin-based perovskite solar cell, comprising the following steps:

S1. Prepare an ITO conductive substrate layer, a hole transport layer and a tin-based perovskite light absorbing layer, wherein the hole transport layer is located on the ITO conductive substrate layer, and the tin-based perovskite light absorbing layer is located on the hole transport layer.

S2, after synthesizing the fullerene di(ethoxycarbonyl)methylene derivative, separating and purifying it to obtain the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e;

S3, weighing the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e according to the mass percentage of the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material and dissolving them in chlorobenzene to obtain a fullerene solution;

S4, after the fullerene solution is heated and stirred, it is allowed to stand and cool, filtered, and then spread on the surface of the tin-based perovskite light-absorbing layer by spin coating, and annealed at 60 to 80° C. for 5 to 15 minutes to obtain a fullerene electron transport layer film;

S5. Spin-coating a BCP hole blocking layer on the fullerene electron transport layer film, and depositing a metal electrode on the BCP hole blocking layer to obtain a tin-based perovskite solar cell.

The present invention also provides a tin-based perovskite solar cell, which is prepared according to the above-mentioned preparation method. The tin-based perovskite solar cell comprises, from bottom to top, an ITO conductive substrate layer, a hole transport layer, a tin-based perovskite light absorption layer, a fullerene electron transport layer, a BCP hole blocking layer and a metal electrode.

The beneficial effects of the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material and application, solar cell and preparation method thereof according to the embodiments of the present invention are:

The present invention separates and purifies and dries the fullerene di(ethoxycarbonyl)methylene derivative with methanol to obtain four positional isomers, namely trans-2, trans-3, trans-4 and e. By rationally allocating the ratios of the four isomers, the ratios between the fullerene isomers can be controlled to reduce energy disorder. The photoelectric conversion efficiency of the tin-based perovskite solar cell prepared by using the electron transport material as the electron transport layer can reach 13.87%.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

FIG1 is a scanning electron microscope image of the interface of the tin-based perovskite solar cell according to Example 1 of the present invention;

FIG2 is a J-V curve diagram of the tin-based perovskite solar cells of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5;

FIG3 is a PCE statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5;

FIG4 is a V _OC statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5;

FIG5 is a J _SC statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5;

FIG6 is a FF statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

Detailed ways

In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

The fullerene bis(ethoxycarbonyl)methylene derivative electron transport material and application, solar cell and preparation method thereof according to the embodiments of the present invention are described in detail below.

An embodiment of the present invention provides a fullerene bis(ethoxycarbonyl)methylene derivative electron transport material, characterized in that it includes isomer trans-2, isomer trans-3, isomer trans-4 and isomer e, and the molecular structures of the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e are respectively:

Among them, in terms of mass percentage, in the fullerene di(ethoxycarbonyl)methylene derivative electron transport material, the mass percentage of the isomer trans-2 is 10% to 30%, the mass percentage of the isomer trans-3 is 25% to 40%, the mass percentage of the isomer trans-4 is 5% to 10%, and the mass percentage of the isomer e is 20% to 60%.

By rationally adjusting the ratio of these four isomers, the film-forming property of the electron transport material can be improved, the energy disorder caused by the change in the isomer ratio can be reduced, the energy level of the electron transport material and the tin-based perovskite can be better matched, and the electron extraction and transmission capacity of the fullerene film can be enhanced. At the same time, it can effectively reduce the energy barrier of carrier diffusion at the interface, reduce the open circuit voltage loss, and thus improve the photoelectric conversion efficiency of tin-based perovskite solar cells.

Furthermore, in a preferred embodiment of the present invention, in terms of mass percentage, in the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material, the mass percentage of the isomer trans-2 is 30%, the mass percentage of the isomer trans-3 is 40%, the mass percentage of the isomer trans-4 is 10%, and the mass percentage of the isomer e is 20%.

The present invention provides the use of the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material in the preparation of tin-based perovskite solar cells.

The present invention provides a method for preparing a tin-based perovskite solar cell, comprising the following steps:

S1. Prepare an ITO conductive substrate layer, a hole transport layer and a tin-based perovskite light absorbing layer, wherein the hole transport layer is located on the ITO conductive substrate layer, and the tin-based perovskite light absorbing layer is located on the hole transport layer.

Specifically, the preparation of the ITO conductive substrate layer, the hole transport layer and the tin-based perovskite light absorbing layer includes the following steps:

Indium tin oxide (ITO) glass was ultrasonicated in acetone, isopropanol and ethanol for 20 minutes, and then treated in ultraviolet ozone for 20 minutes to obtain an ITO conductive substrate layer. Then PEDOT:PSS was dropped on the cleaned ITO conductive substrate layer at a speed of 4000rpm in air, spin-coated for 40s, and annealed at 150℃ for 15min to obtain a hole transport layer. Finally, PEAI, _SnF2 , FAI and _SnI2 were dissolved in a mixed solvent of DMF and DMSO (DMF:DMSO=4:1V/V) and stirred in a glove box at 70℃ for 1h to ensure full dissolution. Subsequently, the dissolved tin-based perovskite precursor solution was dropped on the surface of the PEDOT:PSS film and spin-coated at a speed of 1000rpm and 5000rpm for 10s and 30s, respectively. Among them, 600μL of toluene was added as an anti-solvent at the 20th second of spin coating at a speed of 5000rpm. Finally, annealing was performed at 70°C for 10 min to obtain a tin-based perovskite light-absorbing layer.

S2. After synthesizing the fullerene di(ethoxycarbonyl)methylene derivative, separation and purification are performed to obtain the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e.

The isomer separation and purification steps of the present invention include: separating fullerene di(ethoxycarbonyl)methylene derivatives by high performance liquid chromatography (HPLC), and purifying and drying with methanol to obtain four positional isomers, trans-2, trans-3, trans-4 and e.

S3. Weigh the isomer trans-2, isomer trans-3, isomer trans-4 and isomer e according to the mass percentage of the fullerene bis(ethoxycarbonyl)methylene derivative electron transport material and dissolve them in chlorobenzene to obtain a fullerene solution.

Furthermore, in a preferred embodiment of the present invention, the mass concentration of the fullerene solution is 20-30 mg/mL.

S4, after heating and stirring, the fullerene solution is cooled and filtered, and then spread on the surface of the deposited tin-based perovskite light-absorbing layer by spin coating, and annealed at 60-80°C for 5-15 minutes to obtain a fullerene electron transport layer film. After filtering, the fullerene solution is evenly and fully spread on the surface of the tin-based perovskite light-absorbing layer by spin coating, and annealed to remove the solvent chlorobenzene. Preferably, the annealing temperature is 70°C and the annealing time is 10 minutes.

Furthermore, in a preferred embodiment of the present invention, the heating and stirring step includes: placing the fullerene solution in a glove box at 60-70° C. and heating and stirring for 0.5-1.5 h. The heating and stirring can fully dissolve each isomer in the chlorobenzene solution.

Furthermore, in a preferred embodiment of the present invention, the filtration is performed using a filter head with a pore size of 0.2-0.45 μm. Preferably, 20 minutes before use, the fullerene solution is allowed to cool and filtered using a polytetrafluoroethylene (PTFE) filter head with a pore size of 0.22 μm.

Furthermore, in a preferred embodiment of the present invention, the thickness of the fullerene electron transport layer film is 50-70 nm.

S5. Spin-coating a BCP hole blocking layer on the fullerene electron transport layer film, and depositing a metal electrode on the BCP hole blocking layer to obtain a tin-based perovskite solar cell.

Furthermore, in a preferred embodiment of the present invention, the metal electrode is a gold electrode or a silver electrode, and the thickness of the metal electrode is 90-100 nm. Preferably, the metal electrode is deposited on the hole blocking layer by high vacuum metal thermal evaporation.

1 , the present invention further provides a tin-based perovskite solar cell, which is prepared according to the above-mentioned preparation method, and the tin-based perovskite solar cell includes, from bottom to top, an ITO conductive substrate layer, a hole transport layer, a tin-based perovskite light absorbing layer, a fullerene electron transport layer, a BCP hole blocking layer and a metal electrode.

The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

Example 1

The tin-based perovskite solar cell provided in this embodiment can be prepared according to the following method:

(1) Preparation of ITO conductive substrate layer: Indium tin oxide (ITO) glass was ultrasonicated in acetone, isopropanol and ethanol for 20 min in sequence, and then treated in ultraviolet ozone for 20 min to obtain an ITO conductive substrate layer.

(2) Preparation of hole transport layer: PEDOT:PSS was dropped onto the cleaned ITO conductive substrate layer at a rotation speed of 4000 rpm in air, spin coated for 40 seconds, and annealed at 15°C for 15 minutes.

(3) Preparation of perovskite layer: 14.9 mg PEAI, 9.4 mg _SnF2 , 116.9 mg FAI and 298 mg _SnI2 were dissolved in 1 mL of a mixed solvent of DMF and DMSO (DMF:DMSO = 4:1 V/V) and stirred in a glove box at 70°C for 1 h to ensure full dissolution. The dissolved tin-based perovskite precursor solution was then added dropwise to the surface of the PEDOT:PSS film and spin-coated at 1000 rpm and 5000 rpm for 10 s and 30 s, respectively. In particular, 600 μL of toluene was added as an anti-solvent at 5000 rpm at the 20th second of the spin coating. Finally, annealing was performed at 70°C for 10 min.

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed according to the mass percentage of trans-2, trans-3, trans-4 and e of 30%:40%:10%:20% (that is, the mass ratio between these four isomers is 3:4:1:2). The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a fullerene solution of 20-30 mg/mL. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

(5) Preparation of hole blocking layer: BCP (0.5 mg/mL, isopropanol) was spin coated at 5000 rpm for 30 s and then annealed at 70° C. for 10 min.

(6) Preparation of metal electrodes: Under high vacuum conditions with a gas pressure below 5×10 ^-4 pa, a layer of Ag electrode with a thickness of about 90 to 100 nm is deposited on the hole blocking layer by metal thermal evaporation to obtain a tin-based perovskite battery. Except for PEDOT:PSS, all other operations in the entire preparation process were carried out in a nitrogen glove box, and all solutions used were filtered with a polytetrafluoroethylene (PTFE) filter with a pore size of 0.22 μm.

Example 2

This embodiment provides a tin-based perovskite solar cell, which is mainly different from Embodiment 1 in that:

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed according to the mass percentage of trans-2, trans-3, trans-4 and e of 20%:40%:10%:30% (that is, the mass ratio between the four isomers is 2:4:1:3). The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a 20-30 mg/mL fullerene solution. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

Example 3

This embodiment provides a tin-based perovskite solar cell, which is mainly different from Embodiment 1 in that:

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed according to the mass percentage of trans-2, trans-3, trans-4 and e of 30%:30%:10%:30% (that is, the mass ratio between these four isomers is 3:3:1:3). The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a fullerene solution of 20-30 mg/mL. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

Comparative Example 1

This comparative example provides a tin-based perovskite solar cell, which is mainly different from Example 1 in that:

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed in a mass ratio of 1:2:1:2 for trans-2, trans-3, trans-4 and e. The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a 20-30 mg/mL fullerene solution. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

Comparative Example 2

This comparative example provides a tin-based perovskite solar cell, which is mainly different from Example 1 in that:

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed in a mass ratio of 1:1:1:1 among trans-2, trans-3, trans-4 and e. The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a 20-30 mg/mL fullerene solution. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

Comparative Example 3

This comparative example provides a tin-based perovskite solar cell, which is mainly different from Example 1 in that:

(4) Preparation of fullerene electron transport layer: First, the fullerene di(ethoxycarbonyl)methylene derivative was separated by high performance liquid chromatography (HPLC), purified and dried with methanol to obtain four positional isomers of pure trans-2, trans-3, trans-4 and e, and then mixed in a mass ratio of 2:1:2:1 among trans-2, trans-3, trans-4 and e. The mixture of the above four fullerene isomers was dissolved in chlorobenzene solvent to prepare a 20-30 mg/mL fullerene solution. The fullerene solution was then spin-coated on the surface of the tin-based perovskite layer at a speed of 1500 rpm for 30 seconds and annealed at 70°C for 10 minutes.

Comparative Example 4

This comparative example provides a tin-based perovskite solar cell, which is mainly different from Example 1 in that:

(4) [6,6]-phenyl C ₆₁ -butyric acid methyl ester (PCBM) was dissolved in chlorobenzene to prepare a solution with a concentration of 20-30 mg/mL, and then spin-coated on the surface of the tin-based perovskite layer at a rotation speed of 1500 rpm for 30 seconds, and annealed at 70°C for 10 minutes.

Comparative Example 5

This comparative example provides a tin-based perovskite solar cell, which is mainly different from Example 1 in that:

(4) Indene-C ₆₀ bisadduct (ICBA) was dissolved in chlorobenzene to prepare a solution with a concentration of 20-30 mg/mL, and then spin-coated on the surface of the tin-based perovskite layer at a rotation speed of 1500 rpm for 30 seconds, and annealed at 70°C for 10 minutes.

Test Example 1

This test example tests the photoelectric performance of the tin-based perovskite solar cell of Example 1 and the tin-based perovskite solar cells of Comparative Examples 1 to 5, respectively. The test example includes the following steps:

The current density-voltage characteristic curve of the device was measured under AM 1.5G conditions using an EnliTech, AAA solar simulator. The voltage scan range was 0-1V, the step size was 0.005V, and the delay time was 40ms. The light intensity used in the test was 1000w/ ^m2 , calibrated with a standard silicon solar cell. The effective area of the PSC used for the test was ^0.2cm2 , and a black shadow mask with an effective area of ^0.12cm2 was used to reduce light scattering. The external quantum efficiency (EQE) data was obtained by using an EQE system (EnliTech, QER666) without any bias light. The operating stability of the device was obtained by a thin film photovoltaic decay test system (Suzhou Derui Instrument Equipment Co., Ltd. SQ-1OOK-SOOQ). The dark JV curve was obtained using a CHI660E electrochemical workstation in a dark environment. Among them, the electroluminescence data of the device was measured using a fluorescence quantum efficiency test system of Xipu Optoelectronics Technology Co., Ltd., which was located in a glove box and equipped with an integrating sphere.

The test results are shown in Figures 2 to 6, wherein Figure 2 is a JV curve diagram of the tin-based perovskite solar cells of Examples 1 to 3 and the tin-based perovskite solar cells of Comparative Examples 1 to 5; Figure 3 is a PCE statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 and the tin-based perovskite solar cells of Comparative Examples 1 to 5; Figure 4 is a V _OC statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 and the tin-based perovskite solar cells of Comparative Examples 1 to 5; Figure 5 is a J _SC statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 and the tin-based perovskite solar cells of Comparative Examples 1 to 5; Figure 6 is a FF statistical diagram of the tin-based perovskite solar cells of Examples 1 to 3 and the tin-based perovskite solar cells of Comparative Examples 1 to 5. The photoelectric performance parameters of each tin-based perovskite solar cell in Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1:

Table 1 Photoelectric performance parameters of the optimal devices of each tin-based perovskite solar cell

As shown in Figures 2 to 6 and Table 1, the open circuit voltage of the optimal TPSCs device provided in Example 1 is 0.83V, the short circuit current is 21.71mA/ ^cm2 , the filling factor is 76.88%, and the PCE reaches 13.87%. Its various photoelectric performance parameters are significantly better than those of the TPSCs provided in Examples 2 to 3 and Comparative Examples 1 to 3, and the TPSCs using the monosubstituted fullerene PCBM as the electron transport material in Comparative Example 4. In addition, the open circuit voltage of the optimal TPSCs device using the disubstituted fullerene material ICBA as the electron transport material in Comparative Example 5 is 0.77V, the short circuit current is 19.07mA/ ^cm2 , the filling factor is 72.96%, and the PCE reaches 10.65%. It can be seen that the photoelectric performance of the TPSCs in Example 1 is better than that of the TPSCs in Comparative Example 5, that is, the photoelectric performance of the battery obtained by using the fullerene di(ethoxycarbonyl)methylene derivative electron transport material as the electron transport material is better than that of ICBA which is also a disubstituted fullerene.

The fullerene di(ethoxycarbonyl)methylene derivative electron transport material of the present invention can not only reduce the energy disorder caused by the irregular stacking of the fullerene isomers and promote the extraction and transport of carriers by reasonably regulating the ratio of the isomers, but also inhibit the oxidative corrosion of the tin-based perovskite light-emitting active layer by water and oxygen in the air. At the same time, the energy level of the fullerene di(ethoxycarbonyl)methylene derivative electron transport material is well matched with that of the tin-based perovskite, thereby effectively reducing the energy barrier of carrier diffusion at the interface, reducing the open circuit voltage loss, and improving the photoelectric conversion efficiency of the tin-based perovskite solar cell.

The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims (10)

1. An electron transport material of a fullerene bis (ethoxycarbonyl) methylene derivative, which is characterized by comprising an isomer trans-2, an isomer trans-3, an isomer trans-4 and an isomer e, wherein the molecular structures of the isomer trans-2, the isomer trans-3, the isomer trans-4 and the isomer e are respectively as follows:

，

Wherein, in terms of mass percent, in the fullerene di (ethoxycarbonyl) methylene derivative electron transport material, the mass percent of the isomer trans-2 is 10% -30%, the mass percent of the isomer trans-3 is 25% -40%, the mass percent of the isomer trans-4 is 5% -10%, and the mass percent of the isomer e is 20% -60%.

2. The electron transport material of claim 1, wherein the electron transport material of the fullerene bis (ethoxycarbonyl) methylene derivative has a mass percentage of 30% of the isomer trans-2, a mass percentage of 40% of the isomer trans-3, a mass percentage of 10% of the isomer trans-4, and a mass percentage of 20% of the isomer e.

3. The use of the fullerene bis (ethoxycarbonyl) methylene derivative electron transport material according to any one of claims 1-2 in the preparation of tin-based perovskite solar cells.

4. The preparation method of the tin-based perovskite solar cell is characterized by comprising the following steps of:

S1, preparing an ITO conductive substrate layer, a hole transport layer and a tin-based perovskite light absorption layer, wherein the hole transport layer is positioned on the ITO conductive substrate layer, and the tin-based perovskite light absorption layer is positioned on the hole transport layer;

s2, synthesizing fullerene di (ethoxycarbonyl) methylene derivatives, and then separating and purifying to obtain an isomer trans-2, an isomer trans-3, an isomer trans-4 and an isomer e;

S3, weighing the isomer trans-2, the isomer trans-3, the isomer trans-4 and the isomer e according to the mass percentage of the fullerene di (ethoxycarbonyl) methylene derivative electron transport material of any one of claims 1-2, and dissolving the mixture in chlorobenzene to obtain a fullerene solution;

S4, heating and stirring the fullerene solution, standing, cooling, filtering, spreading on the surface of the tin-based perovskite light absorption layer in a spin coating mode, and annealing for 5-15 min at 60-80 ℃ to obtain a fullerene electron transport layer film;

and S5, spin-coating a BCP hole blocking layer on the fullerene electron transport layer film, and depositing a metal electrode on the BCP hole blocking layer to obtain the tin-based perovskite solar cell.

5. The method for preparing the tin-based perovskite solar cell according to claim 4, wherein the mass concentration of the fullerene solution is 20-30 mg/mL.

6. The method of manufacturing a tin-based perovskite solar cell as claimed in claim 4, wherein in the step S4, the step of heating and stirring includes: and placing the fullerene solution in a glove box at 60-70 ℃ and heating and stirring for 0.5-1.5 h.

7. The method of manufacturing a tin-based perovskite solar cell according to claim 4, wherein in the step S4, a filter head with a pore diameter of 0.2-0.45 μm is used for the filtration.

8. The method of manufacturing a tin-based perovskite solar cell according to claim 4, wherein in the step S4, the thickness of the fullerene electron transport layer film is 50-70 nm.

9. The method of manufacturing a tin-based perovskite solar cell according to claim 4, wherein in the step S5, the metal electrode is a gold electrode or a silver electrode, and the thickness of the metal electrode is 90-100 nm.

10. The tin-based perovskite solar cell is characterized by comprising an ITO conductive substrate layer, a hole transport layer, a tin-based perovskite light absorption layer, a fullerene electron transport layer, a BCP hole blocking layer and a metal electrode from bottom to top in sequence.