An asymmetric organic small-molecule photovoltaic material based on a benzo-phenazine donor core, and a preparation method and application thereof

Abstract

The application discloses a kind of based on benzo phenazine donor core asymmetric organic small molecule photovoltaic material and its preparation method and application.The asymmetric organic small molecule photovoltaic material has structure: wherein, D is donor unit, A is acceptor unit;The donor unit is selected from one of the structures shown in formula I: formula I;In formula I, R 12 Independent selection is one of hydrogen, halogen, trifluoromethyl, alkyl, X is selected from one of sulfur atom or selenium atom;The acceptor unit is selected from one of the structures shown in formula II: formula II;In formula II, R 13 It is selected from one of H, F or Cl;Indicate the connection position of acceptor unit or donor unit.The organic small molecule photovoltaic material designed and synthesized in the application has asymmetry, better molecular packing effect, strong crystallinity and solution processing, and can be used in organic solar cell, to improve its energy conversion efficiency.

Description

Technical Field

[0001] This invention relates to an organic solar cell acceptor material, particularly to an asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core, and also to its preparation method, as well as the application of this type of molecule as an active layer electron acceptor material in organic solar cells, belonging to the field of organic solar cell material preparation technology. Background Technology

[0002] In recent years, organic solar cells (OSCs) have attracted widespread attention from the scientific and industrial communities due to their advantages such as solution-processability, light weight, ease of large-scale fabrication, and suitability for portable power supplies and building-integrated photovoltaics (BIPV). Non-fullerene acceptors possess advantages such as strong absorption in the visible-near-infrared region, easily tunable energy levels, and easily modifiable structures. With the rapid development of material structure and device technology, the optimal photoelectric conversion efficiency of organic solar cells based on non-fullerene acceptor materials has reached 19%.

[0003] However, the photoelectric conversion efficiency of organic solar cells remains lower than that of crystalline silicon and perovskite solar cells. In fact, the fill factor of most high-performance organic solar cells is still limited to 0.75-0.80, and the low carrier mobility of organic semiconductor materials is a significant factor limiting the photoelectric conversion efficiency of organic solar cells. Therefore, further improving the device efficiency of organic solar cells remains challenging. To effectively improve the fill factor of organic solar cells, it is also necessary to optimize the structure of non-fullerene acceptor materials.

[0004] Benzophenes and their derivatives possess advantages such as asymmetric rigid planar structures, ease of chemical modification, and multiple substitution positions, allowing for precise control of their physicochemical properties. Asymmetric small molecule acceptors exhibit larger dipole moments compared to symmetric structures, which enhances intermolecular dipole-dipole interactions, thereby achieving high carrier mobility. How to apply the planarity and easily modified asymmetric benzophenonezine donor units to solution-processable small acceptor molecules to prepare solution-processable organic small acceptor molecules with good planarity, crystallinity, high fill factor, and high efficiency has become an urgent problem to be solved.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide an asymmetric organic small molecule photovoltaic material based on benzophenazine donor core, its preparation method and application, aiming to design and synthesize a solution-processable organic acceptor small molecule with good molecular stacking, strong crystallinity, high fill factor and efficiency, and apply it to organic solar cells, thereby solving the problems of low energy conversion efficiency and fill factor of existing organic solar cells.

[0007] The technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides an asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core, the asymmetric organic small molecule photovoltaic material having the following structure:

[0009]

[0010] Where D is the donor unit and A is the acceptor unit;

[0011] The donor unit is selected from any one of the structures shown in Equation I below:

[0012]

[0013] in, Indicates the location of receptor unit connection;

[0014] R1 and R2 are independently selected from any one of alkyl or aromatic alkyl groups;

[0015] R3 to R 12 It is independently selected from any one of hydrogen, halogen, trifluoromethyl, and alkyl;

[0016] X is independently selected from either sulfur or selenium atoms;

[0017] The receptor unit is independently selected from any one of the structures shown in Formula II below:

[0018]

[0019] in, Indicates the connection position of the body element;

[0020] R 13 It can be independently selected from any one of H, F or Cl.

[0021] Specifically, in this invention, the core shown in Formula I and the end group shown in Formula II can be freely combined to obtain asymmetric organic small molecule photovoltaic materials based on benzophenazine-type donor cores.

[0022] This invention uses a core that expands the conjugation of the intermediate backbone of the traditional acceptor small molecule Y6 (CAS: 2304444-49-1) as the intermediate electron-donating unit, symmetrically connecting electron-withdrawing units such as dicyandioxanone at both ends. This allows for the application of planar and easily chemically modified intermediate donor and acceptor units to the design and synthesis of soluble organic small molecule photovoltaic materials, resulting in solution-processable asymmetric organic acceptor small molecules with good planarity, crystallinity, high fill factor, and high efficiency. The asymmetric organic small molecule photovoltaic material based on a benzopyrazine-based donor core synthesized in this invention, when used as an acceptor material, possesses the advantage of matching HOMO and LUM0 energy levels with the donor material. Furthermore, this type of organic small molecule acceptor material exhibits good reproducibility with no batch-to-batch variation. When the asymmetric organic small molecule photovoltaic material based on a benzopyrazine-based donor core provided in this invention is blended with the polymer donor material PM6, the energy conversion efficiency exceeds 19%, and the fill factor reaches 81%.

[0023] Preferably, R1 is selected from any one of C8-C11 straight-chain alkyl (e.g., C8 straight-chain alkyl, C9 straight-chain alkyl, C10 straight-chain alkyl and C11 straight-chain alkyl), C8-C12 branched alkyl (e.g., C8 branched alkyl, C9 branched alkyl, C10 branched alkyl, C11 branched alkyl and C12 branched alkyl) or C8-C11 aromatic alkyl (e.g., C8 arylalkyl, C9 arylalkyl, C10 arylalkyl and C11 arylalkyl).

[0024] Preferably, R2 is selected from any one of C12-C20 branched alkyl groups (e.g., C12-C20 branched alkyl groups, C13-C14-C15-C16-C17-C18-C19-C20 branched alkyl groups) or C12-20 silane groups (e.g., C12-C13-C14-C15-C16-C17-C18-C19-C20 silane groups).

[0025] More preferably, R1 is selected from C9-C11 straight-chain alkyl groups (e.g., C9 straight-chain alkyl, C10 straight-chain alkyl, and C11 straight-chain alkyl).

[0026] More preferably, R2 is selected from any of the following structures:

[0027]

[0028] Preferably, the receptor unit is selected from any of the following structures:

[0029] in, Indicates the connection location of the body element.

[0030] Preferably, the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core is selected from any one of the following M1-M4:

[0031]

[0032] A second aspect of the present invention provides a method for preparing an asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core as described in the first aspect, characterized in that it includes the following steps:

[0033] (1) Mix the first raw material, phosphorus oxychloride and N,N-dimethylformamide, and react to obtain a dialdehyde-terminated compound;

[0034] (2) The dialdehyde end-group compound, the second raw material, pyridine and chloroform are mixed and reacted to obtain the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core;

[0035] The first raw material is selected from any one of the following compounds:

[0036]

[0037] The second raw material is selected from any one of the following compounds:

[0038]

[0039] Specifically, in step (1), the first raw material containing the donor unit shown in Formula I, the VHA reagent and the halogenating agent are mixed and reacted to obtain a dialdehyde end-group compound; in step (2), the dialdehyde end-group compound obtained in step (1), the second raw material containing the acceptor unit shown in Formula II, pyridine and chloroform are mixed and reacted to obtain the asymmetric organic small molecule photovoltaic material based on the benzophenazine donor core.

[0040] Preferably, in step (1), the molar ratio of the first raw material, DMF and phosphorus oxychloride is 1:(15-50):(15-50), for example, it can be 1:15:15, 1:20:20, 1:20:30, 1:30:30, 1:50:50, etc.; more preferably, the molar ratio of the first raw material, DMF and phosphorus oxychloride is 1:20:20.

[0041] Preferably, in step (1), the mixing temperature is 0-25℃, for example, it can be 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, etc.; more preferably, the mixing temperature is 0-5℃, for example, it can be 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, etc.

[0042] Preferably, in step (1), the reaction temperature is 60-95℃, for example, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, etc.; more preferably, the reaction temperature is 75-85℃, for example, it can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, etc.

[0043] Preferably, in step (1), the reaction time is 12-36 hours, for example, 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, etc.; more preferably, the reaction time is 20-24 hours, for example, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, etc.

[0044] Preferably, in step (1), the reaction is carried out in a chlorinated solvent, which includes any one or a combination of at least two of 1,2-dichloroethane, dichloromethane or trichloromethane; more preferably, the chlorinated solvent is 1,2-dichloroethane (EDC).

[0045] In this invention, in step (1), after the reaction is completed, the reaction solution is cooled to room temperature and then added dropwise to methanol to precipitate. The precipitate is collected by centrifugation. Then, it is purified by silica gel chromatography using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 2:3. The organic solvent is removed by rotary evaporation to obtain a relatively pure dialdehyde end-group compound.

[0046] Preferably, in step (2), the molar ratio of the dialdehyde end-group compound to the second raw material is 1:(4-10), for example, it can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.; more preferably, the molar ratio of the dialdehyde end-group compound to the second raw material is 1:(5-7), for example, it can be 1:5, 1:6, 1:7, etc.

[0047] Preferably, in step (2), the reaction temperature is 30-80℃, for example, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, etc.; more preferably, the reaction temperature is 50-70℃, for example, 50℃, 55℃, 60℃, 65℃, 70℃, etc.

[0048] Preferably, in step (2), the mass ratio of the dialdehyde end-group compound to pyridine is (6-8):100, for example, it can be 6:100, 6.5:100, 7:100, 7.5:100, 8:100, etc.; more preferably, the mass ratio of the dialdehyde end-group compound to pyridine is (7-7.5):100, for example, it can be 7:100, 7.5:100, etc.

[0049] In this invention, in step (2), after the reaction is completed, the reaction solution is cooled to room temperature, and then the reaction solution is added dropwise to methanol to precipitate. The precipitate is collected by centrifugation. Then, the solution is purified by silica gel chromatography using a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 2:3. The organic solvent is removed by rotary evaporation to obtain the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core.

[0050] Preferably, the method for preparing the first raw material includes the following steps:

[0051] (a) The first intermediate and the reducing agent are mixed and reacted to obtain the intermediate product;

[0052] (b) The intermediate product and the second intermediate are mixed and reacted to obtain the first raw material;

[0053] The first intermediate is selected from any one of the following compounds:

[0054]

[0055] The second intermediate is selected from any one of the following compounds:

[0056]

[0057] Preferably, in the preparation method of the first raw material, in step (a), the molar ratio of the first intermediate to the reducing agent is 1:(10-40), for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, etc.; more preferably, the molar ratio of the first intermediate to the reducing agent is 1:(30-40), for example, it can be 1:30, 1:32, 1:34, 1:36, 1:38, 1:40, etc.

[0058] Preferably, in step (a), the reducing agent includes lithium aluminum hydride, zinc powder, and sodium borohydride; more preferably, the reducing agent is lithium aluminum hydride.

[0059] Preferably, in step (a), the reaction temperature is 40-90°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, etc.; more preferably, the reaction temperature is 70-75°C, for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, etc.

[0060] Preferably, in step (a), the reaction time is 12-36 hours, for example, 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, etc.; more preferably, the reaction time is 18-24 hours, for example, 18 hours, 20 hours, 22 hours, 24 hours, etc.

[0061] Preferably, in step (a), the reaction is carried out in a solvent, the solvent including glacial acetic acid and tetrahydrofuran; more preferably, the solvent is tetrahydrofuran.

[0062] Preferably, in step (a), the reaction is carried out in a protective gas atmosphere, the protective gas including any one of nitrogen, argon or helium.

[0063] In this invention, in step (a), after the reaction is completed, the reaction solution obtained after the reaction is cooled to room temperature and then washed with sodium chloride aqueous solution, dried with anhydrous magnesium sulfate, and the solvent is evaporated under vacuum to obtain an intermediate product (brown liquid).

[0064] Preferably, in step (b), the molar ratio of the intermediate product to the second intermediate is 1:(2-4), for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.; more preferably, the molar ratio of the intermediate product to the second intermediate is 1:(2.5-3.5), for example, it can be 1:2.5, 1:3, 1:3.5, etc.

[0065] Preferably, in step (b), the reaction temperature is 30-80℃, for example, it can be 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, etc.

[0066] Preferably, in step (b), the reaction time is 20-24 hours, for example, 20 hours, 22 hours, 24 hours, etc.

[0067] In this invention, in step (b), after the reaction is completed, the reaction solution obtained after the reaction is cooled to room temperature, the crude product is precipitated, the precipitated crude product is collected by centrifugation, and then purified by silica gel chromatography with a mixed solvent of petroleum ether and dichloromethane in a volume ratio of 6:1. The organic solvent is removed by rotary evaporation, thus obtaining the first raw material containing the donor unit shown in Formula I.

[0068] As a preferred embodiment of the present invention, the preparation method of the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core includes the following steps:

[0069] (A) Mix the first intermediate with lithium aluminum hydride and react at 70-75°C for 18-24 h to obtain the intermediate product;

[0070] (B) Mix the intermediate product and the second intermediate obtained in step (A) and react at 30-80℃ for 20-24 hours to obtain the first raw material;

[0071] (C) The first raw material obtained in step (B), DMF and phosphorus oxychloride are mixed at 0-5℃ and reacted at 75-85℃ for 20-24h to obtain a dialdehyde end-group compound;

[0072] (D) The dialdehyde end-group compound obtained in step (C), the second raw material and pyridine are mixed and reacted at 50-70℃ for 2 hours to obtain the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core.

[0073] A third aspect of the present invention provides an application of asymmetric organic small molecule photovoltaic materials based on benzophenazine donor cores, as described in the first aspect, in the fabrication of photovoltaic devices.

[0074] Preferably, the photovoltaic device includes an organic solar cell; the active layer of the organic solar cell includes a donor material and an acceptor material; the acceptor material includes the asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core, and the donor material includes a polymer donor material.

[0075] Preferably, the polymer donor material is PM6.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] (1) In this invention, donor units and acceptor units with good planar structure are applied to the design and synthesis of soluble organic small molecule photovoltaic materials to obtain a series of asymmetric acceptor small molecules with good planarity and good crystallization ability.

[0078] (2) This invention uses the core of the Y6 intermediate backbone of the traditional acceptor small molecule as the intermediate donor unit to synthesize asymmetric organic small molecule photovoltaic materials based on benzophenazine donor cores; such organic small molecule photovoltaic materials have good crystallinity and good solubility in common organic solvents (tetrahydrofuran, dichloromethane, trichloromethane, etc.), and can be used to prepare high-performance organic solar cells by solution method; at the same time, these soluble asymmetric organic small molecule photovoltaic materials have good stacking on the film and all exhibit the characteristics of surface stacking.

[0079] (3) The asymmetric organic small molecule photovoltaic material based on benzophenazine donor core synthesized in this invention has the advantage of matching HOMO and LUM0 energy levels with the donor material as an acceptor material; and such organic small molecule acceptor materials do not have batch differences and have good reproducibility.

[0080] (4) The asymmetric organic small molecule photovoltaic material based on benzophenazine donor core provided by the present invention, when used as an acceptor material, has an energy conversion efficiency of over 19% and a fill factor of up to 81% when blended with polymer donor material PM6. Attached Figure Description

[0081] Figure 1 This is the UV-Vis absorption spectrum of M1 measured in thin film condition.

[0082] Figure 2 This is the UV-Vis absorption spectrum of M2 measured in thin film condition.

[0083] Figure 3 To compare the UV-Vis absorption spectrum of molecule 1 measured in the thin film state.

[0084] Figure 4 The cyclic voltammetry curve for M1 is shown.

[0085] Figure 5 The cyclic voltammetry curve for M2 is shown.

[0086] Figure 6 To compare the cyclic voltammetry curves of molecule 1.

[0087] Figure 7 The JV curve is for the organic solar cell M1.

[0088] Figure 8 The JV curve is for the organic solar cell M2.

[0089] Figure 9 The JV curve of the organic solar cell of molecule 1 is shown for comparison.

[0090] Figure 10 This is the two-dimensional grazing incidence X-ray diffraction pattern of M1.

[0091] Figure 11 This is the two-dimensional grazing incidence X-ray diffraction pattern of M2.

[0092] Figure 12 For comparison, the two-dimensional grazing incidence X-ray diffraction pattern of molecule 1 is shown. Detailed Implementation

[0093] This invention provides an asymmetric organic small molecule photovoltaic material based on a benzophenazine-based donor core, its preparation method, and its applications. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, specific embodiments are provided below for further detailed explanation. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0094] Example 1

[0095] This embodiment provides an asymmetric organic small molecule photovoltaic material M1 based on a benzophenazine donor core, and the synthetic route is shown below:

[0096]

[0097] Synthesis of compound M1-3: In a 100 mL round-bottom flask, 2.0 mmol of compound M1-1 was weighed, and after two purging cycles, 4 mL of a 1 mmol / mL lithium aluminum hydride tetrahydrofuran (THF) solution was added, followed by 20 mL of ultra-dry tetrahydrofuran. The mixture was stirred at 70 °C for 18 hours, then cooled to room temperature. The reaction solution was slowly poured into ice water, extracted, and evaporated to dryness to obtain an intermediate (yellowish-brown liquid). The obtained intermediate was then reacted with compound M1-2 (6 mmol) in THF solution at 70 °C for 18 hours. The reaction solution was cooled to room temperature, extracted, and evaporated to dryness. The resulting solid product was separated by silica gel (200-300 mesh) column chromatography using petroleum ether / dichloromethane as the eluent. The product was a red solid, which was compound M1-3.

[0098] Synthesis of compound M1-4: In a 100 mL three-necked flask, compound M1-3 (0.5 mmol) and anhydrous DMF (10 mL) were added. The mixture was in an ice-water bath for five minutes, followed by the addition of phosphorus oxychloride (2 mL) and 1,2-dichloroethane (20 mL). The mixture was stirred for 2 hours. The temperature was raised to 70 °C and stirred overnight. After cooling to room temperature, the mixture was extracted with dichloromethane, and the solvent was evaporated. The crude product was purified by silica gel column chromatography (petroleum ether / CH2Cl2 = 1:2) to obtain a bright orange solid compound, which was compound M1-4.

[0099] Synthesis of compound M1: Compound M1-4 (0.2 mmol) and compound M1-5 (1 mmol) were added sequentially to a 50 mL two-necked flask, and the mixture was purged three times. Then, chloroform (20 mL) was added under N2 purging, and the mixture was stirred for 5 min to completely dissolve both compounds. Pyridine (0.8 mL) was then added, and the solution slowly turned green. The mixture was refluxed at 65 °C for 20 h to evaporate most of the solvent. The crude product was washed with methanol to remove excess compound M1-5, and further purified by column chromatography using petroleum ether:dichloromethane (2:3) as the eluent to obtain compound M1, a dark blue solid. C, 72.14; H, 6.81; N, 7.01; S, 12.04; Found value: C, 72.18; H, 6.85; N, 7.99; S, 12.09.

[0100] The UV-Vis absorption spectrum based on M1 is as follows: Figure 1 As shown, the cyclic voltammetry curve is as follows: Figure 4 As shown, the two-dimensional grazing incidence X-ray diffraction pattern of the pure M1 film is as follows. Figure 10 As shown.

[0101] Example 2

[0102] This embodiment provides an asymmetric organic small molecule photovoltaic material M2 based on a benzophenazine donor core. The synthetic route is shown below:

[0103]

[0104] Synthesis of compound M2-2: In a 100 mL round-bottom flask, 2.0 mmol of compound M1-1 was weighed, and after two purging cycles, 4 mL of a 1 mmol / mL lithium aluminum hydride tetrahydrofuran (THF) solution was added, followed by 20 mL of ultra-dry tetrahydrofuran. The mixture was stirred at 70 °C for 18 hours, then cooled to room temperature. The reaction solution was slowly poured into ice water, extracted, and evaporated to dryness to obtain an intermediate (yellowish-brown liquid). The obtained intermediate and compound M2-1 (6 mmol) were then reacted in THF solution at 70 °C for 18 hours. The reaction solution was cooled to room temperature, extracted, and evaporated to dryness. The resulting solid product was separated by silica gel (200-300 mesh) column chromatography using petroleum ether / dichloromethane as the eluent. The product was a red solid, which was compound M2-2.

[0105] Synthesis of compound M2-3: In a 100 mL three-necked flask, compound M2-2 (0.5 mmol) and anhydrous DMF (10 mL) were added. The mixture was in an ice-water bath for five minutes, followed by the addition of phosphorus oxychloride (2 mL) and 1,2-dichloroethane (20 mL). The mixture was stirred for 2 hours. The temperature was raised to 70 °C and stirred overnight. After cooling to room temperature, the mixture was extracted with dichloromethane, and the solvent was evaporated. The crude product was purified by silica gel column chromatography (petroleum ether / CH2Cl2 = 1:2) to obtain a bright orange solid compound, which was compound M2-3.

[0106] Synthesis of compound M2: Compound M2-3 (0.2 mmol) and compound M2-4 (1 mmol) were added sequentially to a 50 mL two-necked flask, and the mixture was purged three times. Then, chloroform (20 mL) was added under N2 purging, and the mixture was stirred for 5 min to completely dissolve both compounds. Pyridine (0.8 mL) was then added, and the solution slowly turned green. The mixture was refluxed at 65 °C for 20 h to evaporate most of the solvent. The crude product was washed with methanol to remove excess compound M2-4, and further purified by column chromatography using petroleum ether:dichloromethane (2:3) as the eluent to obtain compound M2, a dark blue solid. C, 70.96; H, 6.37; N, 6.62; S, 7.58; Found value: C, 70.93; H, 6.40; N, 6.59; S, 7.52.

[0107] The UV-Vis absorption spectrum based on M2 is as follows: Figure 2 As shown, the cyclic voltammetry curve is as follows: Figure 5 As shown, the two-dimensional grazing incidence X-ray diffraction pattern of the pure M2 film is as follows. Figure 11 As shown.

[0108] Comparative molecule 1: The structure of reported symmetric organic small molecule photovoltaic materials based on quinoxaline donor cores

[0109]

[0110] Based on the UV-Vis absorption spectrum of contrast molecule 1, as follows Figure 3 As shown, the cyclic voltammetry curve is as follows: Figure 6 As shown, the two-dimensional grazing incidence X-ray diffraction pattern of the pure film of molecule 1 is as follows: Figure 12 As shown.

[0111] Depend on Figure 10-12 It can be seen that, compared with the symmetrical contrast molecule 1, M1 and M2, which have asymmetrical structures, exhibit more obvious face-to-face packing characteristics and stronger crystallization characteristics, which is conducive to achieving high carrier mobility and filling factor.

[0112] Application Example 1

[0113] Methods for fabrication and performance testing of solar photovoltaic devices:

[0114] Commercially purchased indium tin oxide (ITO) glass was first cleaned with detergent, then ultrasonically cleaned sequentially with water, deionized water, acetone, and isopropanol. After drying, a 30 nm thick polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS, weight ratio 1:1, model 4083) anode modification layer was spin-coated and dried at 150°C for 15 minutes for later use. The asymmetric organic small molecule photovoltaic materials M1 and M2 based on benzophenonezine donor cores from Examples 1 and 2 were spin-coated with polymer donor material PM6 (weight ratio 1:0.8, 15 mg / ml) onto the PEDOT:PSS (4083) anode modification layer to form the active layer of the device. The effective area of ​​the photovoltaic device active layer was 4 mm². 2 Vacuum (3×10⁻⁶) on the active layer -5 Aluminum metal with a vapor deposition thickness of about 50 nm is used as the cathode of the photovoltaic device.

[0115] A Newport 500W xenon lamp equipped with an AM1.5 filter was used as a simulated solar light source at 100mW / cm². 2 Photovoltaic performance tests were performed on the device under light intensity, which was calibrated using a standard monocrystalline silicon solar cell. The JV curve was measured using a Keithley 236 and controlled by a computer via LabVIEW software.

[0116] The structure of the polymer donor material used in this invention is as follows:

[0117]

[0118] The JV curve of the organic solar cell fabricated by M1 is as follows: Figure 7 As shown. By Figure 7 It can be seen that the measured short-circuit current Jsc of the device is (26.14) mA cm. -2 The open-circuit voltage Voc is (0.889)V, the fill factor FF is (79.85)%, and the power conversion efficiency PCE is (18.56)%.

[0119] The JV curve of the organic solar cell prepared by M2 is as follows: Figure 8 As shown. By Figure 8 It can be seen that the measured short-circuit current Jsc of the device is (26.34) mA cm. -2 The open-circuit voltage Voc is (0.902)V, the fill factor FF is (81.02)%, and the power conversion efficiency PCE is (19.25)%.

[0120] The JV curve of the organic solar cell prepared by molecule 1 is as follows: Figure 9 As shown. By Figure 9 It can be seen that the measured short-circuit current Jsc of the device is (25.74) mA cm. -2 The open-circuit voltage Voc is (0.899)V, the fill factor FF is (74.13)%, and the power conversion efficiency PCE is (17.15)%.

[0121] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An asymmetric organic small molecule photovoltaic material based on a benzophenazine-based donor core, characterized in that, The asymmetric organic small molecule photovoltaic material has the following structure: ； Where D is the donor unit and A is the acceptor unit; The donor unit is selected from any one of the structures shown in Equation I below: Formula I; in, Indicates the location of receptor unit connection; R1 is selected from any one of C8-C11 straight-chain alkyl, C8-C12 branched alkyl, or C8-C11 arylalkyl; R2 is selected from any one of C12-C20 branched alkyl or C12-20 silyl alkyl; R3 to R 12 It is independently selected from any one of hydrogen, halogen, trifluoromethyl, and alkyl; X is independently selected from either sulfur or selenium atoms; The receptor unit is independently selected from any one of the structures shown in Formula II below: Formula II; in, Indicates the connection position of the body element; R 13 It can be independently selected from any one of H, F or Cl.

2. The asymmetric organic small molecule photovoltaic material based on benzophenazine-based donor cores according to claim 1, characterized in that, R1 is selected from C9-C11 straight-chain alkyl groups.

3. The asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core according to claim 1, characterized in that, R2 is selected from any of the following structures: 。 4. The asymmetric organic small molecule photovoltaic material based on a benzophenazine-based donor core according to claim 1, characterized in that, The asymmetric organic small molecule photovoltaic material based on benzophenazine donor cores is selected from any one of the following M1-M4: 。 5. A method for preparing an asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core as described in any one of claims 1-4, characterized in that, Including the following steps: The first raw material, phosphorus oxychloride and N,N-dimethylformamide were mixed and reacted to obtain a dialdehyde-terminated compound; The dialdehyde end-group compound, the second raw material, pyridine and chloroform are mixed and reacted to obtain the asymmetric organic small molecule photovoltaic material based on benzophenazine donor core. The first raw material is selected from any one of the following compounds: ； The second raw material is selected from any one of the following compounds: 。 6. The method for preparing asymmetric organic small molecule photovoltaic materials based on benzophenazine-based donor cores according to claim 5, characterized in that, The preparation method of the first raw material includes the following steps: The first intermediate and the reducing agent are mixed and reacted to obtain the intermediate product; The intermediate product and the second intermediate are mixed and reacted to obtain the first raw material; The first intermediate is selected from any one of the following compounds: ； The second intermediate is selected from any one of the following compounds: 。 7. The application of an asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core as described in any one of claims 1-4 in the fabrication of photovoltaic devices.

8. The application according to claim 7, characterized in that, The photovoltaic device is selected from organic solar cells; the active layer of the organic solar cell includes a donor material and an acceptor material; the acceptor material includes the asymmetric organic small molecule photovoltaic material based on a benzophenazine donor core, and the donor material includes a polymer donor material.

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