A water-soluble electron transport layer material, a preparation method thereof, an electron transport layer and an organic solar cell

Abstract

The application belongs to the technical field of solar cells, and particularly relates to a water-soluble electron transport layer material, a preparation method thereof, an electron transport layer and an organic solar cell. Through synergistic optimization of the molecular structure, chemical composition and preparation process of the water-soluble electron transport layer material, the comprehensive improvement of the material in the aspects of work function regulation, optical performance, conductive performance and stability is realized, the interface defects between the material and the active layer are effectively reduced, the interface compatibility is enhanced, and then the photoelectric conversion efficiency and overall performance of the organic solar cell are significantly improved, which lays a solid foundation for the wide application of the organic solar cell in the field of clean energy.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a water-soluble electron transport layer material and its preparation method, an electron transport layer, and an organic solar cell. Background Technology

[0002] Against the backdrop of the global energy structure's accelerated transition to clean energy, organic solar cells (OSCs) have garnered widespread attention in research and industry due to their significant advantages, including low cost, large-area fabrication via solution processing, and flexibility. Currently, the photoelectric conversion efficiency of a single conventional OSC device has successfully exceeded 20%. While innovation in the photoactive layer material is undoubtedly a key direction for improving device performance in the structural design and development of OSCs, the charge extraction and transport efficiency at the interface also has a decisive impact on the overall device performance. Among these, the electron transport layer, as the crucial connection between the active layer and the electrodes, plays an irreplaceable role in promoting the selective collection and transport of electrons and reducing the interfacial energy barrier. Traditional electron transport materials and related preparation processes face numerous unresolved issues. Polar solvents such as methanol, ethanol, tetrahydrofuran, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) are commonly used in the preparation of electron transport layers. However, most of these solvents are toxic, causing environmental pollution during production, use, and disposal, and posing potential threats to the health of operators. This contradicts the concept of green and sustainable development, thus limiting the green development of the organic solar cell industry.

[0003] Existing electron transport layer materials also face challenges. Taking the traditional metal oxide zinc oxide (ZnO) as an example, while it possesses some electron transport capabilities, its photocatalytic properties accelerate the decomposition of active materials under long-term light exposure when used in inverted devices, severely limiting device stability and lifespan, and significantly restricting its practical applications. Organic small-molecule electron transport layer materials perform reasonably well in some performance indicators, but they struggle to overcome inherent defects such as poor solubility and suboptimal film quality. This makes large-scale solution processing extremely difficult, failing to meet the demands of industrial production. While the strategy of introducing functional groups into the polymer backbone to prepare electron transport layer materials is theoretically feasible, practical operation faces severe challenges due to complex synthesis processes and high costs, undoubtedly setting insurmountable obstacles to its commercialization. Compared to the aforementioned organic solvents, water offers unparalleled advantages as a solvent. Water is environmentally friendly and pollution-free, aligning with the global trend of green development; its raw material sources are extremely abundant, and its acquisition cost is low, effectively reducing production costs. Based on these significant advantages, developing water-soluble electron transport layer materials can not only solve the environmental pollution and health risks associated with traditional solvents but also fully utilize water's low cost and easy availability, meeting the needs of large-scale industrial production and opening up new pathways for the development of organic solar cells.

[0004] With the continuous advancement of technology, the performance requirements for OSCs (Optical System Capabilities) devices are becoming increasingly stringent, especially in the field of thick-film processing. The market demand for electron transport layer materials with strong work function modification capabilities, weak or no absorption in the visible light region, high conductivity, and good stability is becoming increasingly urgent. At the same time, improving the interfacial compatibility between the material and the active layer and reducing interfacial defects have become crucial issues that urgently need to be addressed in the current OSC research field. Solving these problems is of paramount importance for further improving the overall performance of OSCs and promoting their large-scale commercial application. Summary of the Invention

[0005] The purpose of this invention is to provide a water-soluble electron transport layer material and its preparation method, as well as an electron transport layer and an organic solar cell. This invention aims to significantly improve the overall performance of organic solar cells through material innovation and technology optimization, injecting new vitality into their commercialization process and providing a practical green technology solution.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a water-soluble electron transport layer material having the structure shown in Formula I: Formula I; R1, R2, R3 and R4 are independently unsubstituted or substituted alkyl or unsubstituted or substituted alkoxy groups; The Ar includes unsubstituted or substituted carbocyclic aryl groups or unsubstituted or substituted heterocyclic aryl groups.

[0007] Preferably, the alkyl group comprises C1-C12C46 ... 20 Straight-chain alkyl or C1-C 20 Branched alkyl groups; The C1-C 20 Straight-chain alkyl groups include methyl, ethyl, propyl, butyl, pentyl, or hexyl; The alkoxy group includes C1-C 20 Straight-chain alkoxy or C1-C 20 Branched alkoxy groups; the C1-C 20 Directly linked alkoxy groups include pentoxy or hexoxy groups; The substituent groups in the substituted alkyl or substituted alkoxy groups include halogens, hydroxyl groups, or nitro groups.

[0008] Preferably, the heteroatom on the heterocyclic aryl group includes any one of B, N, P, S, Si, and Se; The carbocyclic aryl or heterocyclic aryl group includes phenyl or polycyclic aryl groups, wherein the number of carbon atoms in the polycyclic aryl group does not exceed 60. The substituent groups on the substituted carbocyclic aryl or substituted heterocyclic aryl include halogen, alkyl, alkoxy, nitro, cyclic ether, or thioether groups.

[0009] Preferably, the Ar includes any one of the following structural compounds; .

[0010] Preferably, X1 is F - Cl - ,Br - I - OH - HSO4 - OTf - HCO3 - BF4 - ,Tf2N - and NO3 - Any one of them.

[0011] Preferably, the water-soluble electron transport layer material comprises any one of the following structural compounds: .

[0012] This invention also provides a method for preparing the water-soluble electron transport layer material described in the above technical solution, comprising the following steps: The compound with the structure shown in Formula 1 and the compound with the structure shown in Formula 2 are first mixed with a solvent to carry out a first reaction, thereby obtaining the compound with the structure shown in Formula 3. The compound with the structure shown in Formula 3 and the compound with the structure shown in Formula 4 are mixed with a solvent to carry out a second reaction, thereby obtaining the water-soluble electron transport layer material. Compounds with the structure shown in Formula 1; Compounds with the structure shown in Formula 2; Compounds with the structure shown in Formula 3; Compounds with the structure shown in Formula 4.

[0013] Preferably, in the first reaction, the molar ratio of the compound with the structure shown in Formula 1 to the compound with the structure shown in Formula 2 is 1:4~10; the ratio of the compound with the structure shown in Formula 1 to the solvent is 1 mmol: 5~300 mL; the temperature of the first reaction is 60~180 ℃, and the time is 6~48 h; In the second reaction, the molar ratio of the compound with the structure shown in Formula 3 to the compound with the structure shown in Formula 4 is 1:2~8; the ratio of the amount of the compound with the structure shown in Formula 3 to the amount of solvent is 1 mmol:10 mL; the temperature of the second reaction is 40~100 °C, and the time is 4~24 h.

[0014] The present invention also provides an electron transport layer, the raw material for which is the water-soluble electron transport layer material described in the above technical solution or the water-soluble electron transport layer material prepared by the preparation method described in the above technical solution.

[0015] The present invention also provides an organic solar cell, including the electron transport layer described in the above technical solution.

[0016] Compared with the prior art, the beneficial effects of the present invention include: The water-soluble electron transport layer material, its preparation method, and its application in organic solar cells provided by this invention have several significant advantages over existing technologies. These advantages are closely related to the core technologies of this invention, as follows: (1) Excellent environmental friendliness and low cost: Existing electron transport layer preparation often uses toxic polar solvents such as methanol and ethanol, which pose environmental pollution and health risks. The water-soluble electron transport layer material provided by this invention uses water as a solvent in the application process. Water has the characteristics of being environmentally friendly, pollution-free, widely available, and inexpensive, thus solving the drawbacks of traditional solvents from the source. Based on this technical point, this invention not only conforms to the concept of green and sustainable development, but also significantly reduces production costs, providing strong support for the large-scale industrial production of organic solar cells and significantly enhancing the green competitiveness of the industry. (2) Good stability and long lifespan: Traditional metal oxide electron transport layer materials (such as zinc oxide) have photocatalytic properties, which can accelerate the decomposition of active materials and affect the stability and lifespan of devices. The water-soluble electron transport layer material developed in this invention avoids the side effects of photocatalysis through molecular structure design and functional group regulation. It improves the stability of the device under light conditions from the material's essence, extends the lifespan of organic solar cells, and provides a guarantee for their long-term stable operation.

[0017] (3) Excellent solution processing performance: Organic small molecule electron transport layer materials suffer from poor solubility and poor film quality, making it difficult to meet the needs of industrial production. The water-soluble electron transport layer material of this invention can use water as a solvent and utilize the special interaction between water molecules and material molecules to significantly improve the solubility and film-forming properties of the material. During solution processing, it can form a uniform and dense electron transport layer film, ensuring consistency and stability in large-scale preparation and effectively solving the problems of traditional materials in solution processing. (4) Simplified synthesis process and reduced cost: Introducing functional groups into the polymer backbone to prepare electron transport layer materials faces the challenges of complex synthesis processes and high costs. This invention optimizes the preparation method of water-soluble electron transport layer materials through innovative synthesis routes and molecular design, reduces cumbersome reaction steps and the use of expensive raw materials, lowers the synthesis difficulty and cost, improves production efficiency, and makes the material preparation easier to realize industrial production, thus accelerating the commercialization process of organic solar cells. (5) Comprehensive performance improvement: In response to the market demand for electron transport layer materials with strong work function modification capabilities, weak or no absorption in the visible light region, high conductivity and good stability, this invention achieves comprehensive improvement in work function regulation, optical performance, conductivity and stability of water-soluble electron transport layer materials through synergistic optimization of molecular structure, chemical composition and preparation process. This effectively reduces interface defects between the material and the active layer, enhances interface compatibility, and significantly improves the photoelectric conversion efficiency and overall performance of organic solar cells, laying a solid foundation for the widespread application of organic solar cells in the field of clean energy. Attached Figure Description

[0018] Figure 1 The JV curve is for the solar cell in Comparative Example 1; Figure 2 The JV curve of the solar cell in Example 3; Figure 3 The JV curve is for the solar cell of Example 4. Detailed Implementation

[0019] This invention provides a water-soluble electron transport layer material having the structure shown in Formula I: Formula I; R1, R2, R3 and R4 are independently unsubstituted or substituted alkyl or unsubstituted or substituted alkoxy groups; The Ar includes unsubstituted or substituted carbocyclic aryl groups or unsubstituted or substituted heterocyclic aryl groups.

[0020] In this invention, the alkyl group preferably comprises C1-C2. 20Straight-chain alkyl or C1-C 20 Branched alkyl groups; the C1-C 20 The straight-chain alkyl group preferably includes methyl, ethyl, propyl, butyl, pentyl, or hexyl; the alkoxy group preferably includes C1-C. 20 Straight-chain alkoxy or C1-C 20 Branched alkoxy groups; the C1-C 20 The direct alkoxy group preferably includes pentoxy or hexoxy; the substituent group in the substituted alkyl or substituted alkoxy group preferably includes halogen, hydroxyl or nitro.

[0021] In this invention, the heteroatom on the heterocyclic aryl group preferably includes any one of B, N, P, S, Si, and Se; the carbocyclic aryl or heterocyclic aryl group preferably includes phenyl or polycyclic aryl, and the number of carbon atoms in the polycyclic aryl group preferably does not exceed 60; the polycyclic aryl group preferably includes naphthyl, anthraceneyl, or pyreneyl; the substituent group on the substituted carbocyclic aryl or substituted heterocyclic aryl group preferably includes halogen, alkyl, alkoxy, nitro, cyclic ether, or thioether groups.

[0022] In this invention, the Ar preferably comprises any one of the following structural compounds: .

[0023] In this invention, X1 is preferably F. - Cl - ,Br - I - OH - HSO4 - OTf - HCO3 - BF4 - ,Tf2N - and NO3 - Any one of them.

[0024] In this invention, the water-soluble electron transport layer material preferably comprises any one of the following structural compounds: .

[0025] This invention also provides a method for preparing the water-soluble electron transport layer material described in the above technical solution, comprising the following steps: The compound with the structure shown in Formula 1 and the compound with the structure shown in Formula 2 are first mixed with a solvent to carry out a first reaction, thereby obtaining the compound with the structure shown in Formula 3. The compound with the structure shown in Formula 3 and the compound with the structure shown in Formula 4 are mixed with a solvent to carry out a second reaction, thereby obtaining the water-soluble electron transport layer material. Compounds with the structure shown in Formula 1; Compounds with the structure shown in Formula 2; Compounds with the structure shown in Formula 3; Compounds with the structure shown in Formula 4.

[0026] In this invention, the compound with the structure shown in Formula 1, the compound with the structure shown in Formula 2, and a solvent are first mixed and subjected to a first reaction to obtain the compound with the structure shown in Formula 3.

[0027] In this invention, the molar ratio of the compound with the structure shown in Formula 1 to the compound with the structure shown in Formula 2 is preferably 1:4 to 10, specifically 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10.

[0028] In this invention, the solvent in the first mixture preferably includes at least one selected from alcohol solvents, organic acid solvents, amide solvents, and imidazole; the alcohol solvent preferably includes at least one selected from ethanol and butanol; the organic acid solvent preferably includes acetic acid; and the amide solvent preferably includes N,N-dimethylformamide. In this invention, the preferred ratio of the compound with the structure shown in Formula 1 to the solvent is 1 mmol: 5~300 mL, specifically 1 mmol: 5 mL, 1 mmol: 50 mL, 1 mmol: 100 mL, 1 mmol: 150 mL, 1 mmol: 200 mL, 1 mmol: 250 mL, or 1 mmol: 300 mL.

[0029] In this invention, the temperature of the first reaction is preferably 60~180℃, specifically 60℃, 80℃, 100℃, 120℃, 140℃, 160℃, or 180℃; the time is preferably 6~48 h, specifically 6h, 12h, 18h, 24h, 30h, 36h, 42h, or 48h.

[0030] In this invention, after the first reaction, a post-treatment is preferably performed; the post-treatment preferably includes: cooling the obtained reaction system to room temperature, pouring it into 200 mL of ice water, filtering to obtain a red precipitate, and washing it sequentially with ultrapure water and methyl tert-butyl ether.

[0031] After obtaining the compound with the structure shown in Formula 3, the present invention mixes the compound with the structure shown in Formula 3, the compound with the structure shown in Formula 4, and a solvent to carry out a second reaction to obtain the water-soluble electron transport layer material.

[0032] In this invention, the molar ratio of the compound with the structure shown in Formula 3 to the compound with the structure shown in Formula 4 is preferably 1:2 to 8, specifically 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, or 1:8.

[0033] In this invention, the solvent in the second mixture preferably includes trifluoroethanol and chloroform; the volume ratio of trifluoroethanol to chloroform is preferably 1:1 to 10, specifically 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. In this invention, the preferred ratio of the compound with the structure shown in Formula 3 to the solvent is 1 mmol: 10 mL.

[0034] In this invention, the temperature of the second reaction is preferably 40~100℃, specifically 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃; the time is preferably 4~24 h, specifically 4h, 6h, 12h, 18h, or 24h.

[0035] In this invention, after the second reaction, it is preferable to perform a post-treatment; the post-treatment preferably includes: cooling the obtained reaction system to room temperature, removing the solvent, pouring it into 200 mL of water, filtering to remove the red precipitate, collecting the filtrate, and removing the solvent.

[0036] The schematic diagram of the preparation method provided by this invention is as follows: .

[0037] The present invention also provides an electron transport layer, the raw material for which is the water-soluble electron transport layer material described in the above technical solution or the water-soluble electron transport layer material prepared by the preparation method described in the above technical solution.

[0038] In this invention, the preferred method for preparing the electron transport layer includes: dissolving the water-soluble electron transport layer material in water, and spin-coating the resulting solution to obtain the electron transport layer. In this invention, the concentration of the solution is preferably 1 mg / mL. This invention does not impose any particular limitation on the spin-coating process; any process well-known to those skilled in the art can be used.

[0039] The present invention also provides an organic solar cell, including the electron transport layer described in the above technical solution.

[0040] In this invention, the organic solar cell preferably comprises a transparent conductive glass, a hole transport layer, an active layer, an electron transport layer, and a metal electrode stacked sequentially.

[0041] In this invention, the transparent conductive glass is preferably indium tin oxide (ITO).

[0042] In this invention, the material of the hole transport layer preferably includes 2PACZ; the thickness of the hole transport layer is preferably 2 nm.

[0043] In this invention, the material of the active layer preferably includes PM6:Y6; the thickness of the active layer is preferably 110 nm.

[0044] In this invention, the thickness of the electron transport layer is preferably 7 nm.

[0045] In this invention, the material of the metal electrode preferably includes silver; the thickness of the metal electrode is preferably 100 nm.

[0046] The present invention does not impose any particular limitation on the preparation method of the organic solar cell. The preparation of the hole transport layer, the active layer and the metal electrode can be carried out using preparation processes well known to those skilled in the art. The preparation method of the electron transport layer is preferably the same as that described in the above technical solution, and will not be repeated here.

[0047] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0048] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0049] Example 1 The synthesis route in this embodiment: (1) Synthesis of compound 3: 3,4,9,10-tetracarboxylic anhydride (0.78 g, 2 mmol), N,N-dimethyl-1,3-diaminopropane (0.82 g, 8 mmol) and 1 mL of n-butanol were placed in a 100 mL single-necked round-bottom flask; the solution was heated at 100 °C for 20 h, cooled to room temperature, poured into 200 mL of ice water, filtered to obtain a red precipitate, and washed successively with ultrapure water and methyl tert-butyl ether to obtain compound 3 (0.92 g, yield 82.0%). (2) Synthesis of compound W-PDI: Compound 3 (0.56 g, 1 mmol), 2-bromoethanol (0.50 g, 4 mmol), 5 mL of trifluoroethanol and 5 mL of chloroform were placed in a 50 mL single-necked round-bottom flask; the solution was heated at 60 °C for 10 h, cooled to room temperature, the solvent was removed, and the solution was poured into 200 mL of water. The red precipitate was removed by filtration, the filtrate was collected, the solvent was removed, and pure compound W-PDI (0.80 g, yield 99.0%) was obtained.

[0050] Example 2 The synthesis route in this embodiment is as follows: (1) Synthesis of compound 3: 1,4,5,8-naphthalenetetracarboxylic anhydride (0.54 g, 2 mmol), N,N-dimethyl-1,3-diaminopropane (0.82 g, 8 mmol) and 15 mL of n-butanol were placed in a 100 mL single-necked round-bottom flask; the solution was heated at 100 °C for 20 h, cooled to room temperature, poured into 200 mL of ice water, filtered to obtain a red precipitate, and washed successively with ultrapure water and methyl tert-butyl ether to obtain compound 3 (0.92 g, yield 82.0%). (2) Synthesis of compound W-NDI: Compound 3 (0.44 g, 1 mmol), 2-bromoethanol (0.50 g, 4 mmol), 5 mL of trifluoroethanol and 5 mL of chloroform were placed in a 50 mL single-necked round-bottom flask; the solution was heated at 60 °C for 10 h, cooled to room temperature, the solvent was removed, and the solution was poured into 200 mL of water. The red precipitate was removed by filtration, the filtrate was collected, the solvent was removed, and compound W-NDI (0.69 g, yield 99.0%) was obtained.

[0051] Example 3 The preparation of an organic solar cell includes the following steps: The structure is: indium tin oxide (ITO) / hole transport layer / active layer / electron transport layer / metal electrode; The ITO-coated glass substrate was cleaned sequentially with a detergent-containing aqueous solution, ultrapure water, acetone and isopropanol, dried with nitrogen, and then treated in an ultraviolet ozone generator for 15 minutes. In a nitrogen atmosphere, a hole transport layer (2PACZ) solution of 0.27 mg / mL was prepared using ethanol, spin-coated onto an ITO-coated glass substrate, and annealed at 100 °C for 10 min to form a hole transport layer with a thickness of 2 nm. A DIB solution with a concentration of 12.5 mg / mL was prepared using chloroform, and then PM6:Y6 (mass ratio 1:1.2) was added to prepare an active layer solution with a concentration of 16 mg / mL. This solution was then spin-coated onto the hole transport layer and annealed at 100 °C for 10 min to form an active layer with a thickness of 100 nm. Then, a solution of compound W-PDI (Example 1) prepared with water at a concentration of 1 mg / mL was spin-coated to obtain an electron transport layer with a thickness of 7 nm. Finally, an Ag layer with a thickness of 100 nm is deposited as a metal electrode to obtain the organic solar cell.

[0052] Example 4 The preparation of an organic solar cell includes the following steps: The structure is: indium tin oxide (ITO) / hole transport layer / active layer / electron transport layer / metal electrode; The ITO-coated glass substrate was cleaned sequentially with a detergent-containing aqueous solution, ultrapure water, acetone and isopropanol, dried with nitrogen, and then treated in an ultraviolet ozone generator for 15 minutes. In a nitrogen atmosphere, a hole transport layer (2PACZ) solution of 0.27 mg / mL was prepared using ethanol, spin-coated onto an ITO-coated glass substrate, and annealed at 100 °C for 10 min to form a hole transport layer with a thickness of 2 nm. Then, PM6:Y6 was prepared in a mass ratio of 1:1.2 using chloroform to form a 12.5 mg / mL DIB solution, which was then used to prepare a 16 mg / mL active layer solution. This solution was spin-coated onto a glass substrate with an ITO coating modified by a hole transport layer (2PACZ). After annealing at 100°C for 10 min, an active layer with a thickness of 100 nm was formed. Then, a solution of compound W-NDI (Example 2) prepared with water at a concentration of 1 mg / mL was spin-coated to obtain an electron transport layer with a thickness of 7 nm. Finally, an Ag layer with a thickness of 100 nm is deposited as a metal electrode to obtain the organic solar cell.

[0053] Comparative Example 1 An organic solar cell was prepared according to the method of Example 3, wherein the electron transport layer material was replaced with PDIN, which has the following structure: .

[0054] Performance testing The photovoltaic parameters of the organic solar cells obtained from the test examples and comparative examples were tested under the following conditions: JV characteristics were tested in an N2-filled glove box with a Keithley 2400 source meter under simulated AM1.5G illumination using a 300W Xe lamp solar simulator (SS-F5-3A, ENLITECH), with intensity corrected by certified standard silicon solar cells. See the obtained JV curve. Figures 1-3 ,in Figure 1 The JV curve is for the solar cell in Comparative Example 1. Figure 2 The JV curve of the solar cell in Example 3 is shown. Figure 3 The JV curve of the solar cell in Example 4; See Table 1 for specific results; Table 1. Photovoltaic parameters of solar cells obtained in the examples and comparative examples.

[0055] from Figures 1-3 As can be seen from Table 1, the efficiency of the solar cells based on Examples 3 and 4 is better than that of the solar cell based on Comparative Example 1.

[0056] 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. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A water-soluble electron transport layer material, characterized in that, It has the structure shown in Equation I: Formula I; R1, R2, R3 and R4 are independently unsubstituted or substituted alkyl or unsubstituted or substituted alkoxy groups; The Ar includes unsubstituted or substituted carbocyclic aryl groups or unsubstituted or substituted heterocyclic aryl groups.

2. The water-soluble electron transport layer material according to claim 1, characterized in that, The alkyl group includes C1-C 20 Straight-chain alkyl or C1-C 20 Branched alkyl groups; The C1-C 20 Straight-chain alkyl groups include methyl, ethyl, propyl, butyl, pentyl, or hexyl; The alkoxy group includes C1-C 20 Straight-chain alkoxy or C1-C 20 Branched alkoxy groups; the C1-C 20 Directly linked alkoxy groups include pentoxy or hexoxy groups; The substituent groups in the substituted alkyl or substituted alkoxy groups include halogens, hydroxyl groups, or nitro groups.

3. The water-soluble electron transport layer material according to claim 1, characterized in that, The heteroatom on the heterocyclic aryl group includes any one of B, N, P, S, Si, and Se; The carbocyclic aryl or heterocyclic aryl group includes phenyl or polycyclic aryl groups, wherein the number of carbon atoms in the polycyclic aryl group does not exceed 60. The substituent groups on the substituted carbocyclic aryl or substituted heterocyclic aryl include halogen, alkyl, alkoxy, nitro, cyclic ether, or thioether groups.

4. The water-soluble electron transport layer material according to claim 1 or 3, characterized in that, The Ar includes any one of the following structural compounds; 。 5. The water-soluble electron transport layer material according to claim 1, characterized in that, X1 is F - Cl - ,Br - I - OH - HSO4 - OTf - HCO3 - BF4 - ,Tf2N - and NO3 - Any one of them.

6. The water-soluble electron transport layer material according to claim 1, characterized in that, The water-soluble electron transport layer material includes any one of the following structural compounds: 。 7. The method for preparing the water-soluble electron transport layer material according to any one of claims 1 to 6, characterized in that, Includes the following steps: The compound with the structure shown in Formula 1 and the compound with the structure shown in Formula 2 are first mixed with a solvent to carry out a first reaction, thereby obtaining the compound with the structure shown in Formula 3. The compound with the structure shown in Formula 3 and the compound with the structure shown in Formula 4 are mixed with a solvent to carry out a second reaction, thereby obtaining the water-soluble electron transport layer material. Compounds with the structure shown in Formula 1; Compounds with the structure shown in Formula 2; Compounds with the structure shown in Formula 3; Compounds with the structure shown in Formula 4.

8. The preparation method according to claim 7, characterized in that, In the first reaction, the molar ratio of the compound with the structure shown in Formula 1 to the compound with the structure shown in Formula 2 is 1:4~10; the ratio of the compound with the structure shown in Formula 1 to the solvent is 1 mmol:5~300 mL; the temperature of the first reaction is 60~180 ℃, and the time is 6~48 h; In the second reaction, the molar ratio of the compound with the structure shown in Formula 3 to the compound with the structure shown in Formula 4 is 1:2~8; the ratio of the amount of the compound with the structure shown in Formula 3 to the amount of solvent is 1 mmol:10 mL; the temperature of the second reaction is 40~100℃ and the time is 4~24 h.

9. An electron transport layer, characterized in that, The raw materials for its preparation are the water-soluble electron transport layer material as described in any one of claims 1 to 6 or the water-soluble electron transport layer material prepared by the preparation method described in claim 7 or 8.

10. An organic solar cell, characterized in that, Includes the electronic transport layer as described in claim 9.

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