A fused ring electron acceptor material based on trifluoromethylthio modification and a preparation method and application thereof

Abstract

The application discloses a kind of based on trifluoromethyl sulfanyl modification fused ring electron acceptor material and preparation method and application thereof, it is related to organic solar cell material technical field.The based on trifluoromethyl sulfanyl modification fused ring electron acceptor material includes the quinoxaline thiophene fused ring unit central core containing trifluoromethyl sulfanyl and electron-withdrawing end group, electron-withdrawing end group is connected at the two ends of central core, its preparation process is with fused ring thiadiazole compound as raw material, sequentially through reduction reaction, cyclization and Vilsmeier-Haack reaction obtains the phenazine thiophene fused ring unit central core containing trifluoromethyl sulfanyl, and then end group structure is introduced by Knoevenagel reaction.The acceptor material solubility is good, it is easy to solution processing into film, and have good coplanarity and conformational stability, for preparing organic solar cell device, reach 19.4% single junction cell photoelectric conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of organic solar cell materials technology, specifically to a fused ring electron acceptor material based on trifluoromethylthioyl modification, its preparation method, and its application. Background Technology

[0002] Organic solar cells (OSCs) have shown significant application potential in portable electronics, wearable devices, and building-integrated photovoltaics (BIPV) due to their advantages such as lightweight, flexibility, wide availability of materials, and solution processing capabilities. In recent years, through molecular design strategies such as end-group substitution, side-chain engineering, and central core modification, the power conversion efficiency of single-junction OSCs based on A-DA'DA type non-fullerene acceptors has exceeded 20%. However, compared to inorganic and perovskite solar cells, OSCs still face bottlenecks such as high exciton binding energy, high non-radiative energy loss, and low carrier mobility, which limit further efficiency improvements. Therefore, developing novel acceptor materials that can simultaneously improve open-circuit voltage, short-circuit current density, and fill factor remains a key challenge in this field.

[0003] In acceptor molecular design, central core engineering, particularly the modification of electron-deficient A' units, has become a core strategy for constructing highly efficient non-fullerene acceptors. Represented by Y6, various electron-deficient units such as benzotriazole, benzothiadiazole, and quinoxaline (Qx) have been successively employed. Among them, Qx has attracted attention due to its combination of a rigid molecular framework (beneficial for reducing recombination energy) and flexible substitution sites (facilitating the modulation of photoelectric properties). Further, through two-dimensional conjugation extension of the central core, a tight π-π stack can be formed, improving charge mobility. However, the extension of aromatic rings significantly reduces the average molecular electrostatic potential of the acceptor, thereby weakening the electrostatic potential difference at the donor / acceptor interface, which is detrimental to exciton dissociation. For example, the conjugated extended acceptor CH4 reported in the literature has an average electrostatic potential as low as 4.23 kcal / mol, resulting in insufficient driving force for exciton dissociation, and the corresponding device efficiency is only 16.4%. Angew. Chem. Int. Ed . 2022, 134, e202209580].

[0004] To improve the average electrostatic potential, the current mainstream strategy is to halogenate the central core, with fluorine atoms being the most widely used due to their strong electronegativity and small atomic radius. Central core fluorination can also promote self-assembly, increase crystallinity, and improve charge mobility through the formation of intramolecular / intermolecular interactions such as F…H and F…S. However, existing fluorination strategies still have significant limitations: the improvement in average electrostatic potential from a single fluorine atom is limited; and while introducing trifluoromethyl groups can significantly improve charge separation, it leads to an excessively high proportion of charge-transferred states in the donor-acceptor excited states, reducing luminescence efficiency and increasing non-radiative energy loss.

[0005] Therefore, it is urgent to explore new fluorination unit or molecular design strategies to achieve a balance between charge separation efficiency and energy loss, thereby achieving a synergistic improvement in short-circuit current, open-circuit voltage and fill factor. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned shortcomings and problems of the prior art by providing a novel quinoxaline-based central nuclear modified acceptor, its preparation method, and its application, thereby further improving the photoelectric conversion performance of organic solar cells.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a fused-ring electron acceptor material based on trifluoromethylthioyl modification, the general structural formula of which is shown below: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups; It can be any one of the following groups, where the dashed lines indicate the connection positions: in, R3 is a hydrogen atom, a halogen substituent, or a cyano group; R4 is a hydrogen atom, a halogen substituent, or a cyano group.

[0008] The acceptor material of the present invention comprises a phenazine-thiophene fused ring unit central core containing a trifluoromethylthio group and an electron-withdrawing end group, wherein the electron-withdrawing end group is connected to both ends of the central core to form an n-type non-fullerene acceptor material with an A-DA'DA type conjugated structure, and has the following structural characteristics: (i) it has strong absorption in the visible-near infrared region and a wide absorption spectrum; (ii) a trifluoromethylthio group (SCF3) is introduced on the phenazine parent ring of the central core, which has a moderate electron-withdrawing ability.

[0009] According to a second aspect of the present invention, the present invention also provides a method for preparing a fused-ring electron acceptor material based on trifluoromethylthioyl modification, comprising the following steps: (1) After reduction, fused-ring thiadiazole compounds are used to generate intermediate a; The structural formula of the fused-ring thiadiazole compound is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups; The structural formula of intermediate a is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups.

[0010] (2) Intermediate a was cyclized with 4-trifluoromethylthio-1,2-phenylenediamine to obtain intermediate b; The structural formula of the 4-trifluoromethylthio-1,2-phenylenediamine compound is: The structural formula of intermediate b is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups.

[0011] (3) Intermediate b undergoes a Vilsmeier-Haack reaction to obtain intermediate c; The structural formula of the intermediate c is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups.

[0012] (4) Intermediate c reacts with compound EG via Knoevenagel to obtain a fused ring electron acceptor material based on trifluoromethylthio group modification; The compound EG is any one of the following: in, R3 is a hydrogen atom, a halogen substituent, or a cyano group; R4 is a hydrogen atom, a halogen substituent, or a cyano group.

[0013] As a further preferred technical solution of the present invention, the solvent is tetrahydrofuran, the reducing agent is lithium aluminum hydride, and the reaction is carried out at a temperature of 70-100 °C for 8-12 hours with a molar ratio of fused-ring thiadiazole compound to lithium aluminum hydride of 1:5 to 1:10. And / or, the cyclization reaction is carried out under the following conditions: using chloroform as the solvent, reacting at room temperature for 6 to 12 hours with the molar ratio of intermediate a to 4-trifluoromethylthio-1,2-phenylenediamine compound being 1:5 to 10. And / or, the conditions for the Vilsmeier-Haack reaction are as follows: using 1,2-dichloroethane as the solvent, phosphorus oxychloride as the formylation reagent, and refluxing at 80-100 °C for 9-12 hours with a molar ratio of intermediate b to phosphorus oxychloride of 1:20-1:30; And / or, the conditions for the Knoevenagel reaction are as follows: using toluene as solvent, boron trifluoride diethyl ether complex and acetic anhydride as catalysts, with a molar ratio of intermediate to compound EG of 1:2 to 1:2.8, and reacting at room temperature for 30 to 60 minutes.

[0014] According to a third aspect of the present invention, the present invention also provides an application of a trifluoromethylthio-modified fused-ring electron acceptor material as an acceptor material for organic solar cells.

[0015] As a further preferred technical solution of the present invention, a photoelectric conversion layer is made by combining a trifluoromethylthio-modified fused ring electron acceptor material and an electron donor material for use in organic solar cell devices.

[0016] As a further preferred embodiment of the present invention, the molar ratio of the fused ring electron acceptor material based on trifluoromethylthioyl modification to the electron donor material is 1:1 to 1:1.5.

[0017] As a further preferred embodiment of the present invention, the electron donor material is at least one of PM6, D18, PBDB-T and other organic electron donor materials.

[0018] According to a fourth aspect of the present invention, the present invention also provides an organic solar cell, wherein the photoelectric conversion layer employs the fused ring electron acceptor material based on trifluoromethylthioyl modification as described in the first aspect.

[0019] Compared with the prior art, the present invention can achieve the following beneficial effects: Compared with the prior art, the technical solution of the present invention has the following significant advantages: This invention provides a fused-ring electron acceptor material based on trifluoromethylthioyl (SCF3) modification. For the first time, a trifluoromethylthioyl (SCF3) group is introduced into the quinoxaline (phenazine) central core of a non-fullerene acceptor. Its moderate electron-withdrawing ability allows for precise control of the molecular electrostatic potential, significantly reducing non-radiative energy loss while ensuring efficient exciton dissociation. On one hand, the introduction of SCF3 induces multiple non-covalent intermolecular interactions, forming a unique three-dimensional honeycomb network structure with multiple π-π stacking modes, significantly enhancing intermolecular interactions and improving carrier mobility. On the other hand, SCF3 has high lipophilicity, resulting in good solubility in common solvents such as chloroform, toluene, o-xylene, and chlorobenzene, enabling room-temperature solution processing, making it particularly suitable for the fabrication of large-area devices.

[0020] The fused ring electron acceptor material based on trifluoromethylthioyl modification provided by this invention can achieve high-efficiency photovoltaic performance with different donor materials (such as PM6, D18, PBDB-T) and has good donor compatibility.

[0021] The synthetic route of the trifluoromethylthio-modified fused ring electron acceptor material provided by this invention is simple, the raw materials are readily available, and it is conducive to large-scale production and application. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Figure 1 It is the organic small molecule receptor ZY-SCF3-HD shown in Example 1. 1 H NMR.

[0024] Figure 2 This is the organic small molecule receptor CH-CF3 shown in Example 1. 1 H NMR.

[0025] Figure 3 It is the organic small molecule receptor ZY-SCF3-HD shown in Example 1. 13 C NMR.

[0026] Figure 4 This is the organic small molecule receptor CH-CF3 shown in Example 1. 13 C NMR.

[0027] Figure 5 This is the UV-Vis-NIR absorption spectrum of the organic small molecule receptor ZY-SCF3-HD shown in Example 1.

[0028] Figure 6 This is the UV-Vis-NIR absorption spectrum of the organic small molecule receptor CH-CF3 shown in Comparative Example 1.

[0029] Figure 7 The cyclic voltammetry curves are those of the organic small molecule receptor ZY-SCF3-HD shown in Example 1.

[0030] Figure 8 The cyclic voltammetry curves for the organic small molecule receptor CH-CF3 shown in Comparative Example 1 are shown.

[0031] Figure 9 This is the current density-voltage curve of the organic solar cell prepared by the organic small molecule acceptor ZY-SCF3-HD and the donor PM6 as shown in Example 1.

[0032] Figure 10 This is a current density-voltage curve of an organic solar cell prepared by organic small molecule acceptor CH-CF3 and donor PM6 as shown in Comparative Example 1.

[0033] Figure 11 This is the current density-voltage curve of the organic solar cell prepared by the organic small molecule acceptor ZY-SCF3-HD and the donor D18 as shown in Example 1.

[0034] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0036] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0037] Example 1 The fused-ring electron acceptor material based on trifluoromethylthioyl modification provided in this embodiment has the following structural formula: In the above structural formula, R1 is taken as R2 is taken , Pick The organic small molecule acceptor material was named ZY-SCF3-HD, and its specific synthetic route is as follows: The specific synthesis method of this receptor material is as follows: (1) Synthesis of intermediate A: Compound 1 (600 mg, 0.50 mmol) and solvent tetrahydrofuran (30 mL) were added to a two-necked flask. Under nitrogen protection, lithium aluminum hydride (95 mg) was added. The resulting mixture was stirred and heated to reflux for 12 hours. After cooling to 0°C, water (30 mL) was slowly added dropwise to the reaction mixture. The mixture was extracted with dichloromethane and dried over anhydrous magnesium sulfate. The solvent was removed by rotary evaporation to obtain intermediate A.

[0038] (2) Synthesis of intermediate B: The crude product of intermediate A obtained above was added to chloroform (20 mL), followed by the sequential addition of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (565.7 mg) and 4-trifluoromethylthio-1,2-phenylenediamine dihydrochloride (702.8 mg). The reaction was stirred at room temperature for 6 h, and after removing the solvent under vacuum, the product was purified by silica gel column chromatography (dichloromethane / n-hexane = 1:5) to obtain a purplish-black intermediate B (469.0 mg, yield of 70% in the above two steps).

[0039] (3) Synthesis of intermediate C: Under nitrogen protection, compound 4 (460 mg, 0.343 mmol) and 1,2-dichloroethane (15 ml) were added to a two-necked flask, followed by the addition of anhydrous N,N-dimethylformamide (1 ml) and phosphorus oxychloride (1.2 ml). The resulting mixture was stirred and heated to reflux for 12 hours. After the reaction was complete, the reaction solution was quenched in a saturated aqueous solution of sodium bicarbonate. The mixture was extracted with dichloromethane and dried over anhydrous magnesium sulfate. The mixture was then purified by silica gel column chromatography (CH2Cl2 / n-hexane = 1:1 (v / v)) to obtain a red solid, which was intermediate C.

[0040] (4) Synthesis of target compound D (ZY-SCF3-HD): The intermediate C obtained above, 5,6-difluoro-3-3-(dicyanomethylene)indophenone (194.7 mg, 0.86 mmol), boron trifluoride diethyl ether complex (0.2 ml), and acetic anhydride (1.0 ml) were reacted in toluene (20 mL) for 30 min. After removing the solvent under vacuum, the mixture was purified by silica gel column chromatography (dichloromethane / n-hexane = 1:1 (v / v)) to give a black solid ZY-SCF3-HD (380.9 mg, yield of the above two steps was 61%).

[0041] The nuclear magnetic resonance (NMR) data results are as follows: 1 H NMR (600 MHz, CDCl3) δ 9.14 (s, 2H), 8.68 (s, 1H), 8.55-8.49 (m,2H), 8.34 (d, J= 8.7 Hz, 1H), 8.00 (d, J = 8.7 Hz, 1H), 7.72 (t, J = 7.3 Hz,2H), 4.84 (d, J = 7.7 Hz, 4H), 3.27 (t, J = 7.8 Hz, 4H), 2.25 (s, 2H), 1.90 (p, J = 7.8 Hz, 4H), 1.43 - 1.24 (m, 40H), 1.15 - 0.96 (m, 40H), 0.86 (t, J = 6.8 Hz,6H), 0.73 (t, J = 7.3 Hz, 6H), 0.68 (t, J = 6.7 Hz, 6H). 13 C NMR (151 MHz, CDCl3) δ 185.11, 157.З7, 154.16, 152.93, 152.51, 152.44, 145.31, 145.29, 140.65,139.72, 138.01, 137.65, 136.82, 136.79, 136.54, 135.51, 134.84, 133.93,133.71, 133.42, 132.85, 132.63, 132.19, 130.28, 129.49, 129.OS, 127.44,124.57, 118.69, 117.99, 117.90, 113.89, 113.72, 113.39, 111.53, 111.42,SS.89, 39.70, 30.89, 30.87, 30.42, 30.37, 29.19, 28.92, 28.85, 28.67, 28.65,28.63, 28.61, 28.56, 28.53, 28.33, 28.30, २6.92, 22.48, 22.40, 22.01, 21.65,21.64, 13.05, 13.04, 12.82, 9.46, 9.42. 19 F NMR (565 MHz, CDCl3) δ -41.66, -122.95, -124.32. Comparative Example 1 Please note that there seems to be a character encoding issue in the original text where "З" is likely a misrepresentation. I've translated it as best as possible while keeping the original format. If this was a specific symbol that should be translated differently, more context would be needed.Referring to the synthetic route of Example 1, only the reagent 4-trifluoromethylthio-1,2-phenylenediamine dihydrochloride (containing -SCF3) in synthetic step (2) was replaced with 4-trifluoromethyl-1,2-phenylenediamine (containing -CF3). The other raw materials, feed ratios, reaction conditions, and purification methods were kept the same as in Example 1, and the target product CH-CF3 was obtained. The synthetic route is as follows: The NMR data results for CH-CF3 are as follows: 1 H NMR (600 MHz, CDCl3) δ 9.05 (d, 2H), 8.62-8.30 (m, 4H), 7.92 (d,1H), 7.64 (t, 2H), 4.78 (d, 4H), 3.18 (d, 4H), 2.19 (s, 2H), 1.81 (t, 4H), 1.53-1.18 (m, 40H), 0.96 (d, 40H), 0.79-0.65 (m, 12H), 0.60 (d, 6H). 13 C NMR(151 MHz, CDCl3) δ 185.11, 157.65, 154.24, 153.02, 145.34, 145.27, 141.39,139.34, 138.56, 138.16, 136.75, 136.68, 135.57, 134.94, 134.91, 134.14,133.32, 133.04, 132.24, 132.21, 130.79, 130.70, 129.48, 126.40, 118.76,118.72, 117.80, 117.76, 113.93, 113.50, 111.45, 111.32, 67.46, 54.85, 30.89, 30.87, 30.82, 30.61, 28.88, 28.83, 28.68, 28.62, 28.61, 28.53, 28.51, 28.37, 28.34, 28.31, 28.19, 21.64, 21.55, 21.48, 13.07, 13.01, 12.99, -1.04. 19 F NMR (565 MHz, CDCl3) δ -62.30, -122.90, -124.32. The organic small molecule acceptor materials prepared in Example 1 and Comparative Example 1 were subjected to UV-Vis absorption spectroscopy measurements using a UV-Vis spectrophotometer. First, the small molecule acceptor material was dissolved in chloroform, and the light absorption curve of the solution was measured. Then, the chloroform solution of the small molecule acceptor material was spin-coated onto a glass slide to prepare a thin film, and the light absorption curve of the thin film was measured. The test results are as follows: Figures 5-6 As shown.

[0042] from Figure 5 It can be seen that ZY-SCF3-HD has a maximum absorption peak of 742 nm in dilute chloroform solution, a maximum absorption peak of 808 nm in thin film, an absorption edge of 914 nm, and an optical band gap of 1.357 eV.

[0043] from Figure 6 It can be seen that the maximum absorption peak of CH-CF3 in dilute chloroform solution is 738 nm, the maximum absorption peak of thin film is 802 nm, the absorption edge reaches 900 nm, and the optical band gap is 1.378 eV.

[0044] In chloroform solution, the maximum absorption peak of ZY-SCF3-HD showed a redshift compared to CH-CF3, indicating that the intramolecular charge transfer effect of ZY-SCF3-HD is stronger than that of CH-CF3. This suggests that SCF3 has a weaker electron-withdrawing ability than CF3, with a more moderate intensity. Compared to its absorption in solution, ZY-SCF3-HD exhibited a 66 nm redshift in the thin-film state, which is greater than the redshift value of CH-CF3 (64 nm), indicating that the SCF3-containing acceptor has a stronger π-π stacking interaction than its CF3-containing counterpart. ZY-SCF3-HD also exhibited strong absorption and a broad absorption spectrum in the visible to near-infrared region.

[0045] The organic small molecule acceptor materials prepared in Example 1 and Comparative Example 1 were subjected to cyclic voltammetry tests. The initial oxidation and reduction potentials of the molecules were determined by cyclic voltammetry, and the energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were calculated. In this invention, an electrochemical workstation was used for electrochemical property testing, with Ag / AgCl as the reference electrode, a platinum sheet electrode as the auxiliary electrode, and a glassy carbon electrode as the working electrode. The polymer was dissolved in CHCl3 solution and then drop-coated onto the electrode surface to form a thin film. An anhydrous acetonitrile solution of 0.1 mol / L tetrabutylammonium hexafluorophosphate was used as the electrolyte. The potential was calibrated using a ferrocene / ferrocene redox couple. The test results are as follows. Figures 7-8 As shown.

[0046] from Figure 7 It can be seen that the E(HOMO) of ZY-SCF3-HD in Example 1 is... 5.75 eV, E(LUMO) = 3.96 eV.

[0047] from Figure 8 It can be seen that the E(HOMO) of CH-CF3 in Comparative Example 1 is = 5.76 eV, E(LUMO) = 3.94 eV.

[0048] The donors PM6 and D18 used in this invention were both commercially available. A fused-ring electron acceptor material based on trifluoromethylthioyl modification, as provided in this invention, was used as the acceptor in an organic solar cell. The device structure adopted a traditional bulk heterojunction structure (ITO / 2PACz / active layer / PDINN / Ag). The acceptor material and electron donor material were mixed at a mass ratio of 1:1.2. 1,3,5-trichlorobenzene (TCB) was used as an additive, and an appropriate amount of chloroform solvent was added to dissolve the blend. The mixture was then spin-coated onto conductive glass to prepare a thin film, and a metal electrode was deposited onto the film to form an organic solar cell.

[0049] Organic solar cells were fabricated using ZY-SCF3-HD from Example 1 and CH-CF3 from Comparative Example 1 as acceptor materials, respectively. The structures of the organic solar cells were ITO / 2PACz / PM6:ZY-SCF3-HD / PDINN / Ag and ITO / 2PACz / PM6:CH-CF3 / PDINN / Ag, respectively. Furthermore, an organic solar cell with the structure ITO / 2PACz / D18:ZY-SCF3-HD / PDINN / Ag was further fabricated using ZY-SCF3-HD from Example 1 as the acceptor material.

[0050] The specific fabrication process of the organic solar cell is as follows: An etched ITO glass slide is placed on a cleaning rack and ultrasonically treated sequentially with detergent, deionized water, acetone, and isopropanol for 45 min each. The cleaned ITO glass is then dried with a nitrogen gun to remove surface solvent and placed in a plasma cleaner for 3 min. Next, a 0.3 mg / mL 2PACz solution dissolved in ethanol is applied to the ITO glass slide using a static spin-coating method. The slide is then rotated at 3000 rpm for 30 s, placed on a heating stage, and annealed at 90°C for 5 min. Finally, it is transferred to a vacuum glove box. The pre-prepared active layer solutions (PM6:ZY-SCF3-HD, PM6:CH-CF3, and D18:ZY-SCF3-HD) were dissolved in chloroform at a D:A mass ratio of 1:1.2 to a concentration of 15 mg / mL, with 6 mg / mL of 1,3,5-trichlorobenzene (TCB) added as an additive. These solutions were then spin-coated onto the 2PACz interface layer at 2500 rpm. After coating, the layer was placed in a transition chamber for 5 min, annealed in CS2 solvent for 10 s, and finally annealed at 90 °C for 5 min. A PDINN solution at a concentration of 1 mg / mL in methanol was spin-coated at 3000 rpm for 30 s. The common electrode ITO was scraped out using a utility knife. Finally, 120 nm of metallic Ag was deposited onto the active layer surface to obtain the organic solar cell device.

[0051] Under standard sunlight (AM 1.5 G, 100 mW cm⁻¹) -2 The performance of the aforementioned organic solar cell device was tested under irradiation. The current density-voltage curve of the organic solar cell is shown below. Figures 9-11 As shown in Table 1, the specific photovoltaic performance parameters are listed. When PM6 is used as the donor, the open-circuit voltage of the bulk heterojunction organic solar cell device fabricated using ZY-SCF3-HD as the acceptor material is 0.89 V, and the short-circuit current is 26.8 mA cm⁻¹. -2 The fill factor was 81.2%, and the photoelectric conversion efficiency was 19.4%. The bulk heterojunction organic solar cell device fabricated using CH-CF3 as the acceptor material had an open-circuit voltage of 0.88 V and a short-circuit current of 25.8 mA cm⁻¹. -2 The fill factor is 77.5% and the photoelectric conversion efficiency is 17.6%.

[0052] The comparison shows that the PM6:ZY-SCF3-HD device based on the acceptor material of Example 1 has significantly better performance than the PM6:CH-CF3 device based on the acceptor material of Comparative Example 1, achieving a synergistic improvement in short-circuit current, open-circuit voltage and fill factor.

[0053] Furthermore, when the PM6 donor was replaced with the D18 donor, the open-circuit voltage of the bulk heterojunction organic solar cell device based on the ZY-SCF3-HD acceptor material was 0.89 V, and the short-circuit current was 26.9 mA cm⁻¹. -2 The fill factor was 80.0%, and the photoelectric conversion efficiency was 19.2%, which is comparable to the efficiency (19.4%) of the device based on ZY-SCF3-HD as the acceptor with PM6 as the donor. Specific data are shown in Table 1. These results demonstrate that ZY-SCF3-HD, as a fused-ring electron acceptor, can achieve high-efficiency photovoltaic performance with donor materials of different structures such as PM6 and D18, exhibiting good donor compatibility.

[0054] Table 1 While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A fused-ring electron acceptor material based on trifluoromethylthioyl modification, characterized in that, The general structural formula of the receptor material is shown below: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups; It can be any one of the following groups, where the dashed lines indicate the connection positions: in, R3 is a hydrogen atom, a halogen substituent, or a cyano group; R4 is a hydrogen atom, a halogen substituent, or a cyano group.

2. The method for preparing the fused-ring electron acceptor material based on trifluoromethylthioyl modification as described in claim 1, characterized in that, Includes the following steps: (1) After reduction, fused-ring thiadiazole compounds are used to generate intermediate a; The structural formula of the fused-ring thiadiazole compound is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups; The structural formula of intermediate a is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups. (2) Intermediate a was cyclized with 4-trifluoromethylthio-1,2-phenylenediamine to obtain intermediate b; The structural formula of the 4-trifluoromethylthio-1,2-phenylenediamine compound is: The structural formula of intermediate b is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups. (3) Intermediate b undergoes a Vilsmeier-Haack reaction to obtain intermediate c; The structural formula of the intermediate c is: in, R1 is C1-C 18 Straight-chain or branched alkyl groups; R2 is C1-C 18 Straight-chain or branched alkyl groups. (4) Intermediate c reacts with compound EG via Knoevenagel to obtain a fused ring electron acceptor material based on trifluoromethylthio group modification; The compound EG is any one of the following: in, R3 is a hydrogen atom, a halogen substituent, or a cyano group; R4 is a hydrogen atom, a halogen substituent, or a cyano group.

3. The preparation method according to claim 2, characterized in that, The conditions for the reduction reaction are as follows: using tetrahydrofuran as the solvent and lithium aluminum hydride as the reducing agent, the reaction is carried out under reflux at 70-100 °C for 8-12 hours at a molar ratio of fused-ring thiadiazole compound to lithium aluminum hydride of 1:5 to 1:

10. And / or, the cyclization reaction is carried out under the following conditions: using chloroform as the solvent, reacting at room temperature for 6 to 12 hours with the molar ratio of intermediate a to 4-trifluoromethylthio-1,2-phenylenediamine compound being 1:5 to 1:

10. And / or, the conditions for the Vilsmeier-Haack reaction are as follows: using 1,2-dichloroethane as the solvent, phosphorus oxychloride as the formylation reagent, and refluxing at 80-100 °C for 9-12 hours with a molar ratio of intermediate b to phosphorus oxychloride of 1:20-1:30; And / or, the conditions for the Knoevenagel reaction are as follows: using toluene as solvent, boron trifluoride diethyl ether complex and acetic anhydride as catalysts, with a molar ratio of intermediate to compound EG of 1:2 to 1:2.8, and reacting at room temperature for 30 to 60 minutes.

4. The application of the trifluoromethylthio-modified fused-ring electron acceptor material as described in claim 1 as an acceptor material for organic solar cells.

5. The application according to claim 4, characterized in that, A photoelectric conversion layer based on trifluoromethylthio-modified fused-ring electron acceptor material and electron donor material is used in organic solar cell devices.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the fused ring electron acceptor material to the electron donor material based on trifluoromethylthioyl modification is 1:1 to 1.5:

1.

7. The preparation method according to claim 6, characterized in that, The electron donor material is at least one of PM6, D18, and PBDB-T.

8. An organic solar cell, characterized in that, Its photoelectric conversion layer uses the fused ring electron acceptor material based on trifluoromethylthio group modification as described in claim 1.

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