An electron acceptor with a sulfur-containing bridging central unit, its preparation method and application

Abstract

This invention discloses an electron acceptor with a sulfur-containing bridging central unit, its preparation method, and its application, belonging to the field of optoelectronic materials technology. It solves the problem that non-fullerene acceptors in existing technologies cannot simultaneously possess optoelectronic properties and have simple preparation methods. The electron acceptor structure of this sulfur-containing bridging central unit is shown in Formulas I and II; wherein X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen atoms and halogen atoms; Y1 and Y2 are independently selected from any one of sulfur atoms and selenium atoms; R1 and R2 are independently selected from C1-C15 alkyl groups; and R3 and R4 are independently selected from hydrogen atoms and C1-C15 alkyl groups. The organic optoelectronic material prepared by this method is simple to process, easy to purify, and has a well-defined structure. Organic photovoltaic devices prepared using the organic optoelectronic material of this invention exhibit high photoelectric conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials technology, and more specifically to an electron acceptor containing a sulfur-bridging central unit, its preparation method, and its application. Background Art

[0002] Organic solar cells, as a clean and renewable green energy technology, offer advantages such as low cost, light weight, solution-processability, and good mechanical flexibility. In recent years, with the rapid development of organic photoactive layer materials and the continuous improvement of photovoltaic device technology, the power conversion efficiency (PCE) of organic photovoltaic devices has been rapidly improved, achieving a significant breakthrough with PCE exceeding 20%. The design of high-performance non-fullerene acceptors (NFAs) is crucial, yet extremely challenging. The non-fullerene acceptors in the active layer are responsible for capturing low-energy photons, allowing for better matching of the solar spectrum, but also subjecting them to the strict limitations of the "bandgap law."

[0003] Compared to other types of non-fullerene receptors, high-performance Y-series non-fullerene receptors have formed a more compact and ordered three-dimensional (3D) molecular stacking network. The delocalization of molecular vibrations on adjacent stacked molecules helps non-fullerene receptors escape the limitations of the bandgap law, especially for near-infrared (NIR) non-fullerene receptors. More excitingly, further enhancing the molecular stacking strength and order through innovative structural exploration—for example, extending the central unit to two dimensions, considering the irreplaceable role of the central core in determining the molecular stacking pattern and constructing the three-dimensional network—potentially strengthens this advantageous property.

[0004] However, apart from diimide-based structures (such as benzothiadiazole, quinoxaline, or phenazine), very few candidate structures have been successfully developed and become the central core of high-performance non-fullerene acceptors. Therefore, it is crucial to construct high-performance non-fullerene acceptors that satisfy specific photoelectric properties and are easy to synthesize. Summary of the Invention

[0005] This invention provides an electron acceptor containing a sulfur-bridged central unit, its preparation method, and its application, in order to solve the problem that non-fullerene acceptors in the prior art cannot simultaneously possess photoelectric properties and have simple preparation methods.

[0006] In a first aspect, the present invention provides an electron acceptor containing a sulfur-bridged central unit, the structure of which is shown in Formula I to Formula II;

[0007]

[0008] Among them, X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen atoms and halogen atoms; Y1 and Y2 are independently selected from any one of sulfur atoms and selenium atoms; R1 and R2 are independently selected from C1 to C15 alkyl groups; R3 and R4 are independently selected from hydrogen atoms and C1 to C15 alkyl groups.

[0009] A1 and A2 are independently selected from any one of the groups shown in formulas A to D:

[0010]

[0011] Among them, R5, R6, R7, and R8 are independently selected from any one of hydrogen atoms and halogen atoms.

[0012] As one possible implementation, the structure of the electron acceptor of the sulfur-containing bridging central unit is shown in equations (1) to (4);

[0013]

[0014]

[0015] In a second aspect, the present invention provides a method for preparing an electron acceptor of a sulfur-containing bridging central unit as described in any possible implementation of the first aspect, comprising the following steps: mixing a dialdehyde compound, an electron-deficient terminal group precursor compound, an organic solvent and a catalyst, reacting for 24 hours, extracting, combining the organic phases, drying, removing the solvent, and separating by column chromatography to obtain the electron acceptor of the sulfur-containing bridging central unit; wherein the structural formula of the dialdehyde compound is shown in Formulas III to IV.

[0016]

[0017] Wherein, X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen atoms and halogen atoms; Y1 and Y2 are independently selected from any one of sulfur atoms and selenium atoms; R1 and R2 are independently selected from C1 to C15 alkyl groups; R3 and R4 are independently selected from hydrogen atoms and C1 to C15 alkyl groups; the precursor compound with the electron-deficient terminal group is selected from any one of alkanes containing the groups shown in Formulas A to E.

[0018] As one possible implementation, the organic solvent is any one of chloroform, dichloromethane, and tetrahydrofuran; and / or, the catalyst is any one of triethylamine, piperidine, pyridine, ammonium acetate, ammonium propionate, and ammonium butyrate.

[0019] As one possible implementation, the ratio of the organic solvent to the dialdehyde compound is 10 to 20:1 in L / mol; and / or the molar ratio of the catalyst to the dialdehyde compound is 1:5.

[0020] As one possible implementation, the preparation method of the dialdehyde compound includes the following steps: mixing an intermediate donor compound, phosphorus oxychloride, anhydrous N,N-dimethylformamide, and a haloalkane organic solvent, reacting for 6–24 hours, then adding a saturated sodium acetate aqueous solution, reacting at room temperature for 0.5–2 hours, extracting, combining the organic phases, drying, removing the solvent, and separating by column chromatography to obtain the dialdehyde compound; wherein the structural formula of the intermediate donor compound is shown in Formulas V to VI;

[0021]

[0022] Among them, X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen atoms and halogen atoms; Y1 and Y2 are independently selected from any one of sulfur atoms and selenium atoms; R1 and R2 are independently selected from C1 to C15 alkyl groups; and R3 and R4 are independently selected from hydrogen atoms and C1 to C15 alkyl groups.

[0023] As one possible implementation, the haloalkane organic solvent is any one of chloroform, dichloromethane, and 1,2-dichloroethane; and / or, in L / mol, the ratio of the haloalkane organic solvent to the intermediate donor is 10-20:1; and / or, the molar ratio of the intermediate donor, the phosphorus oxychloride, and the anhydrous N,N-dimethylformamide is 1:5:10.

[0024] As one possible implementation, the preparation method of the intermediate donor includes the following steps: after the precursor compound undergoes a cyclization reaction with triphenylphosphine, it undergoes a one-pot substitution reaction with 3-(bromomethyl)heptane / 2-butyl-1-bromooctane to obtain the intermediate donor; wherein the structural formula of the precursor compound is shown in Formulas VII to VIII;

[0025]

[0026] Among them, X1, X2, X3, X4, and X5 are independently selected from any one of hydrogen atoms and halogen atoms; Y1 and Y2 are independently selected from any one of sulfur atoms and selenium atoms; R3 and R4 are independently selected from hydrogen atoms and C1 to C15 alkyl groups.

[0027] Thirdly, the present invention provides an application of the electron acceptor of the sulfur-containing bridging central unit as described in any possible implementation of the first aspect or the electron acceptor of the sulfur-containing bridging central unit prepared by the preparation method described in any possible implementation of the second aspect in organic optoelectronic devices.

[0028] Fourthly, the present invention provides an organic optoelectronic device, wherein the electron acceptor of the sulfur-containing bridging central unit described in any possible implementation of the first aspect or the electron acceptor of the sulfur-containing bridging central unit prepared by the preparation method described in any possible implementation of the second aspect is used as its active layer material.

[0029] As one possible implementation, the device is an organic solar cell, a field-effect transistor, or an organic light-emitting diode.

[0030] This invention provides a method for preparing organic optoelectronic materials that is simple in steps, easy to purify, has a well-defined structure, good solubility, and is easy to process into films. Through moderate chlorination modification of thiaanthracene molecules, the molecular stacking mode and fibrous film morphology are further optimized. Organic photovoltaic devices prepared using the organic optoelectronic materials of this invention as electron acceptor materials exhibit superior photovoltaic performance, with a photoelectric conversion efficiency reaching 19.0%. This innovative work provides a potential pathway for developing novel non-fullerene acceptors and is expected to help devices break through the 20% efficiency bottleneck. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 The ultraviolet-visible absorption spectra of solutions of compounds 1 to 4 provided in the embodiments of the present invention.

[0033] Figure 2 The ultraviolet-visible absorption spectra of the thin films of compounds 1 to 4 provided in the embodiments of the present invention. Detailed Implementation

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] To address the problem that non-fullerene acceptors in the prior art cannot simultaneously possess photoelectric properties and have simple preparation methods, this embodiment provides an electron acceptor with a sulfur-containing bridging central unit, its preparation method, and its application.

[0036] This invention provides a method for preparing organic optoelectronic materials that is simple in steps, easy to purify, has a well-defined structure, good solubility, and is easy to process into films. Through moderate chlorination modification of thiaanthracene molecules, the molecular stacking mode and fibrous film morphology are further optimized. Organic photovoltaic devices prepared using the organic optoelectronic materials of this invention as electron acceptor materials exhibit superior photovoltaic performance, with a photoelectric conversion efficiency reaching 19.0%. This innovative work provides a potential pathway for developing novel non-fullerene acceptors and is expected to help devices break through the 20% efficiency bottleneck.

[0037] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0038] Example 1

[0039] This embodiment provides the preparation of optoelectronic materials.

[0040] Synthesis Route 1:

[0041]

[0042] Synthesis Route 2:

[0043]

[0044] In the above-mentioned "Synthetic Route 1" and "Synthetic Route 2", X1, X2, X3, and X4 are all hydrogen atoms or all chlorine atoms; X5 is a fluorine atom; Y1 and Y2 are all sulfur atoms; R1 and R2 are all n-undecyl; R3 and R4 are all 2-ethylhexyl or all 2-butyloctyl; A1 and A2 are all the following groups:

[0045]

[0046] Among them, R5 and R8 are both hydrogen atoms, and R6 and R7 are both fluorine atoms.

[0047] 1. Synthesis of compound (1):

[0048]

[0049] Under nitrogen protection, potassium carbonate (304 mg, 2.2 mmol) was added to an anhydrous N,N-dimethylformamide (DMF, 15.0 mL) solution of compound 5 (788 mg, 1.00 mmol). After stirring at room temperature for 0.5 hours, o-dithiophenol (142 mg, 1.00 mmol) was added to the mixture. Stirring was continued at room temperature for 30 minutes, followed by quenching with water and extraction three times with dichloromethane. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (v / v 1:8) as eluent to give compound 6 (721 mg, 81% yield) as a yellow solid.

[0050] 1 H NMR(400MHz,Chloroform-d)δ7.12(d,J=7.2Hz,4H),7.06(dd,J=5.8,3.4Hz,2H),6.95(s, 2H), 2.63(t,J=7.7Hz,4H),1.71–1.62(m,4H),1.29–1.13(m,32H),0.75(t,J=6.6Hz,6H). 13 C NMR(101MHz,Chloroform-d)δ143.9,142.8,142.4,138.4,135.1,133.4,131.4,129.1,128 .9,128.2,123.6,123.5,32.1,30.0,29.8,29.8,29.7,29.6,29.6,29.5,28.7,22.8,14.3.

[0051]

[0052] Under a nitrogen atmosphere, triphenylphosphine (PPh3, 10.26 g, 39.10 mmol) was added to a solution of compound 6 (1.74 g, 1.96 mmol) in o-dichlorobenzene (ODCB, 8.5 mL). The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the mixture was rapidly passed through a silica gel column using dichloromethane as the eluent to give a dark red solid crude cyclized product. To avoid oxidation, the crude product was not further purified, but was directly mixed under a nitrogen atmosphere with potassium carbonate (K₂CO₃, 696 mg, 5.04 mmol), potassium iodide (KI, 836 mg, 5.04 mmol), 3-(bromomethyl)heptane (1.05 g, 5.04 mmol), and anhydrous N,N-dimethylformamide (DMF, 15.0 mL). This mixture was stirred at 100 °C for 3 hours. After cooling to room temperature, the reaction was quenched with water and extracted three times with petroleum ether. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether as eluent to give a light yellow solid alkylated product 7 (1.31 g, yield 64%).

[0053] 1 H NMR(400MHz,Chloroform-d)δ7.72(dd,J=5.8,3.3Hz,2H),7.29(dd,J=5.8,3.3Hz,2H),7.01(s,2H),4.56(t,J=7.8Hz,4H ),2.86(t,J=7.7Hz,4H),2.06–1.97(m,2H),1.89(q,J=7.5Hz,4H),1.46–1.29(m,32H),1.11–0.84(m,22H),0.64(m,12H). 13 C NMR(101MHz,Chloroform-d)δ142.7,138.5,136.7,136.4,129.5,129.5,129.2,127.6,123.7,121.6,119.9,119.3,118.9,5 4.8,39.6,32.0,29.8,29.8,29.7,29.7,29.6,29.6,29.5,29.5,28.9,27.7,23.1,23.0,22.8,22.8,14.2,13.8,10.1,10.1.

[0054]

[0055] Under argon protection, phosphorus oxychloride (0.6 mL) was added to a solution of compound 7 (546 mg, 0.52 mmol) and N,N-dimethylformamide (DMF, 0.6 mL) in 1,2-dichloroethane (DCE, 30 mL). The resulting mixture was stirred and refluxed for 12 hours, followed by cooling to 0 °C. The resulting mixture was slowly added to a saturated sodium acetate solution (40 mL), and then stirred at room temperature for 2 hours. The resulting mixture was extracted with dichloromethane, and the organic layer was dried over anhydrous sodium sulfate for 1 hour. After solvent removal, the crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (v / v) as eluent to give compound 8 (510 mg, 88% yield) as a yellow solid.

[0056] 1 H NMR(400MHz,Chloroform-d)δ10.14(s,2H),7.71(dd,J=5.8,3.3Hz,2H),7.31(dd,J=5.8,3.3Hz,2H),4.58(dt,J=8.0, 3.8Hz,4H),3.22(t,J=7.7Hz,4H),1.95(t,J=7.5Hz,6H),1.49–1.26(m,32H),1.06–0.85(m,22H),0.66–0.60(m,12H). 13 C NMR(101MHz,Chloroform-d)δ181.8,146.8,143.7,138.1,138.1,137.1,135.7,130.5,130.5,129.6,129.3,128.0,125.0,124.9 ,121.9,120.7,55.0,39.8,32.0,30.5,29.8,29.7,29.7,29.6,29.5,29.4,29.4,28.2,27.6,23.0,22.7,14.2,13.7,10.1,10.1.

[0057]

[0058] Under argon protection, compound 8 (111 mg, 0.1 mmol), dicyandiamide (115 mg, 0.5 mmol), and 10 mL of dry chloroform were added to a 100 mL double-necked round-bottom flask. Then, 0.2 mL of pyridine was added dropwise to the mixture. The reaction mixture was stirred at 70 °C for 12 hours. After cooling to room temperature, the reaction mixture was poured into 70 mL of methanol to precipitate. The precipitate was purified by silica gel column chromatography using petroleum ether / chloroform (v / v 4:5) as eluent to give the black target compound 1 (131 mg, 86% yield).

[0059] 1 H NMR(400MHz,Chloroform-d)δ9.17(s,2H),8.58(dd,J=10.0,6.4Hz,2H),7.76–7.68(m,4H),7.36(dd,J=5.8,3.3Hz,2H),4.67(d,J=7.5Hz,4H),3.27(t,J=7 .8Hz,4H),2.05–1.99(m,2H),1.90(t,J=7.2Hz,4H),1.56(m,8H),1.40–1.25( m,30H),1.00–0.85(m,16H),0.74–0.64(m,12H).HR-MS(m / z,MALDI):Calc.for C 88 H 90 F4N6O2S6[M + ],1531.5386; found:1531.5429.

[0060] 2. Synthesis of compound (2):

[0061]

[0062] Under nitrogen protection, potassium carbonate (304 mg, 2.2 mmol) was added to an anhydrous N,N-dimethylformamide (DMF, 15.0 mL) solution of compound 5 (788 mg, 1.00 mmol). After stirring at room temperature for 0.5 hours, 3,6-dichloro-1,2-benzenedithiol (211 mg, 1.00 mmol) was added to the mixture. Stirring was continued at room temperature for 30 minutes, followed by quenching with water and extraction three times with dichloromethane. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (v / v 1:8) as eluent to give compound 9 (720 mg, 75% yield) as a yellow solid.

[0063] 1 H NMR(400MHz,Chloroform-d)δ7.43(s,2H),7.33(s,2H),7.20(s,2H),2.87(t,J =7.6Hz,4H),1.90(t,J=7.4Hz,4H),1.47–1.38(m,30H),0.99(t,J=6.6Hz,8H). 13C NMR(101MHz,Chloroform-d)δ143.3,143.1,142.7,138.5,135.1,134.4,132.4,131.0,130 .0,128.9,123.8,123.7,32.1,30.0,29.8,29.8,29.7,29.6,29.5,29.5,28.7,22.9,14.3.

[0064]

[0065] Under a nitrogen atmosphere, triphenylphosphine (PPh3, 10.26 g, 39.10 mmol) was added to a solution of compound 9 (1.88 g, 1.96 mmol) in o-dichlorobenzene (ODCB, 8.5 mL). The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the mixture was rapidly passed through a silica gel column using dichloromethane as the eluent to give a dark red solid crude cyclized product. To avoid oxidation, the crude product was not further purified, but was directly mixed under a nitrogen atmosphere with potassium carbonate (K₂CO₃, 696 mg, 5.04 mmol), potassium iodide (KI, 836 mg, 5.04 mmol), 3-(bromomethyl)heptane (1.05 g, 5.04 mmol), and anhydrous N,N-dimethylformamide (DMF, 15.0 mL). This mixture was stirred at 100 °C for 3 hours. After cooling to room temperature, the reaction was quenched with water and extracted three times with petroleum ether. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether as eluent to give a light yellow solid alkylated product 10 (1.23 g, yield 56%).

[0066] 1 H NMR(400MHz,Chloroform-d)δ7.22(s,2H),7.01(s,2H),4.64(t,J=8.0Hz,4H),2.89(t,J=7.6Hz ,4H),2.14–2.03(m,2H),1.91(p,J=7.5Hz,4H),1.48–1.31(m,32H),0.98(m,22H),0.70(m,12H). 13C NMR(101MHz,Chloroform-d)δ143.2,138.8,138.8,137.5,136.8,132.0,129.8,129.8,128.4,123.6,121.7,119.9,119.9,119. 5,117.9,54.9,39.7,32.1,29.9,29.8,29.8,29.7,29.7,29.6,29.5,28.9,27.8,23.1,23.1,22.9,22.9,14.3,13.8,10.1,10.1.

[0067]

[0068] Under argon protection, phosphorus oxychloride (0.6 mL) was added to a solution of compound 10 (582 mg, 0.52 mmol) and N,N-dimethylformamide (DMF, 0.6 mL) in 1,2-dichloroethane (DCE, 30 mL). The resulting mixture was stirred and refluxed for 12 hours, followed by cooling to 0 °C. The resulting mixture was slowly added to a saturated sodium acetate solution (40 mL), and then stirred at room temperature for 2 hours. The resulting mixture was extracted with dichloromethane, and the organic layer was dried over anhydrous sodium sulfate for 1 hour. After solvent removal, the crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (v / v) as eluent to give compound 11 (475 mg, 88% yield) as a yellow solid.

[0069] 1 H NMR(400MHz,Chloroform-d)δ10.06(s,2H),7.18(s,2H),4.52(q,J=5.5Hz,4H),3.13 (t,J=7.5Hz,4H),1.88(m,6H),1.36–1.14(m,32H),1.00–0.74(m,22H),0.56(m,12H). 13 C NMR(101MHz,Chloroform-d)δ181.8,146.7,144.0,138.3,138.3,137.3,136.8,132.1,130.7,130.7,129.4,128.7,124.8,124.8,1 21.9,119.6,55.1,39.9,32.0,30.6,29.7,29.7,29.6,29.6,29.6,29.4,29.4,28.1,27.7,23.1,22.8,22.7,14.2,13.7,10.1,10.1.

[0070]

[0071] Under argon protection, compound 11 (118 mg, 0.1 mmol), dicyandiamide (115 mg, 0.5 mmol), and 10 mL of dry chloroform were added to a 100 mL double-necked round-bottom flask. Then, 0.2 mL of pyridine was added dropwise to the mixture. The reaction mixture was stirred at 70 °C for 12 hours. After cooling to room temperature, the reaction mixture was poured into 70 mL of methanol to precipitate. The precipitate was purified by silica gel column chromatography using petroleum ether / chloroform (v / v 4:5) as eluent to give the black target compound 2 (136 mg, 85% yield).

[0072] 1 H NMR(400MHz,Chloroform-d)δ9.18(s,2H),8.63–8.54(m,2H),7.72(t,J=7.4Hz,2H),7.40(s,2H),4.70(t,J=7.1Hz,4H),3.28(t,J=7.8H z,4H),2.03(s,2H),1.95–1.86(m,4H),1.55(m,5H),1.41–0.96(m,43H),0.90–0.84(m,6H),0.71(m,12H).HR-MS(m / z,MALDI):Calc.for C 88 H 88 Cl2F4N6O2S6[M + ],1600.4606; found:1600.4617.

[0073] 3. Synthesis of compound (3):

[0074]

[0075] Under nitrogen protection, potassium carbonate (304 mg, 2.2 mmol) was added to an anhydrous N,N-dimethylformamide (DMF, 15.0 mL) solution of compound 5 (788 mg, 1.00 mmol). After stirring at room temperature for 0.5 hours, 3,4,6-trichloro-1,2-benzenedithiol (245 mg, 1.00 mmol) was added to the mixture. Stirring was continued at room temperature for 30 minutes, followed by quenching with water and extraction three times with dichloromethane. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (v / v 1:8) as eluent to give compound 12 (776 mg, 78% yield) as a yellow solid.

[0076] 1HNMR(400MHz,Chloroform-d)δ7.50(s,1H),7.39(d,J=3.7Hz,2H),7.15(s,2H),2.8 3(t,J=7.6Hz,4H),1.87(t,J=7.4Hz,4H),1.45–1.33(m,31H),0.96(t,J=6.6Hz,7H). 13 C NMR(101MHz,Chloroform-d)δ143.4,143.4,142.9,142.7,142.6,138.6,136.5,135.1,134.1,132.7,132.2, 130.9,130.8,130.3,129.1,129.0,124.0,123.8,32.1,30.0,29.9,29.9,29.8,29.6,29.6,28.7,22.9,14.3.

[0077]

[0078] Under a nitrogen atmosphere, triphenylphosphine (PPh3, 10.26 g, 39.10 mmol) was added to a solution of compound 12 (1.95 g, 1.96 mmol) in o-dichlorobenzene (ODCB, 8.5 mL). The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the mixture was rapidly passed through a silica gel column using dichloromethane as the eluent to give a dark red solid crude cyclized product. To avoid oxidation, the crude product was not further purified, but was directly mixed under a nitrogen atmosphere with potassium carbonate (K₂CO₃, 696 mg, 5.04 mmol), potassium iodide (KI, 836 mg, 5.04 mmol), 3-(bromomethyl)heptane (1.05 g, 5.04 mmol), and anhydrous N,N-dimethylformamide (DMF, 15.0 mL). This mixture was stirred at 100 °C for 3 hours. After cooling to room temperature, the reaction was quenched with water and extracted three times with petroleum ether. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using petroleum ether as eluent to give a light yellow solid alkylated product 13 (1.22 g, yield 54%).

[0079] 1 H NMR(400MHz,Chloroform-d)δ7.30(s,1H),6.84(s,2H),4.45(t,J=8.0Hz,4H),2.70(t,J=7.6Hz,4H ),1.95–1.85(m,2H),1.73(t,J=7.4Hz,4H),1.33–1.14(m,32H),0.99–0.73(m,22H),0.52(m,12H). 13C NMR(101MHz,Chloroform-d)δ143.2,143.2,139.7,138.9,136.8,136.8,135.9, 132.2,131.7,130.5,129.9,129.8,129.8,128.7,123.6,121.7,121.7,119.8,1 19.8,119.8,119.7,119.6,117.7,117.5,55.0,39.7,32.1,29.9,29.8,29.8,29.7,29.7,29.6,29.5,28.9,27.8,23.1,23.1,22.9,22.8,14.3,13.8,10.1,10.1.

[0080]

[0081] Under argon protection, phosphorus oxychloride (0.6 mL) was added to a solution of compound 13 (600 mg, 0.52 mmol) and N,N-dimethylformamide (DMF, 0.6 mL) in 1,2-dichloroethane (DCE, 30 mL). The resulting mixture was stirred and refluxed for 12 hours, then cooled to 0 °C. The resulting mixture was slowly added to a saturated sodium acetate solution (40 mL), and then stirred at room temperature for 2 hours. The resulting mixture was extracted with dichloromethane, and the organic layer was dried over anhydrous sodium sulfate for 1 hour. After solvent removal, the crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (v / v) as eluent to give compound 14 (547 mg, 87% yield) as a yellow solid.

[0082] 1 H NMR(400MHz,Chloroform-d)δ10.14(s,2H),7.48(s,1H),4.68–4.52(m,4H),3.22(t,J =7.7Hz,4H),2.01–1.90(m,6H),1.49–1.23(m,35H),1.06–0.85(m,19H),0.64m,12H). 13C NMR(101MHz,Chloroform-d)δ181.8,146.8,146.7,144.0,143.9,139.0,138.4,13 8.3,137.3,135.2,132.7,131.8,130.8,130.8,130.7,130.6,129.4,129.0,124.7 ,124.7,124.6,124.6,121.9,121.8,119.5,119.3,55.1,39.8,32.0,30.6,29.8,29.7,29.7,29.6,29.6,29.4,29.4,28.1,27.6,23.0,22.8,22.7,14.2,13.7,10.1.

[0083]

[0084] Under argon protection, compound 14 (121 mg, 0.1 mmol), dicyandiamide (115 mg, 0.5 mmol), and 10 mL of dry chloroform were added to a 100 mL double-necked round-bottom flask. Then, 0.2 mL of pyridine was added dropwise to the mixture. The reaction mixture was stirred at 70 °C for 12 hours. After cooling to room temperature, the reaction mixture was poured into 70 mL of methanol to precipitate. The precipitate was purified by silica gel column chromatography using petroleum ether / chloroform (v / v 4:5) as eluent to give black compound 3 (132 mg, 81% yield).

[0085] 1 H NMR(400MHz,Chloroform-d)δ9.17(d,J=0.6Hz,2H),8.58(dd,J=7.5,4.8Hz,2H),7.71(t,J=5.6Hz,2H),7.59(s,1H),4.70(t,J=5.3Hz,4H),3.27(t,J=5. 9Hz,4H),2.02(m,2H),1.94–1.85(m,4H),1.59–1.51(m,6H),1.41–1.17(m,3 2H),0.99(m,10H),0.86(m,6H),0.70(m,12H).HR-MS(m / z,MALDI):Calc.for C 88 H 87 Cl3F4N6O2S6[M + ],1635.4187; found:1635.4617.

[0086] 4. Synthesis of compound (4):

[0087]

[0088] Under nitrogen protection, potassium carbonate (304 mg, 2.2 mmol) was added to an anhydrous N,N-dimethylformamide (DMF, 15.0 mL) solution of compound 5 (788 mg, 1.00 mmol). After stirring at room temperature for 0.5 hours, 3,4-dichlorothiophenol (179 mg, 1.00 mmol) was added to the mixture. Stirring was continued at room temperature for 30 minutes, followed by quenching with water and extraction three times with dichloromethane. The organic layer was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using dichloromethane and petroleum ether (v / v 1:8) as eluent to give compound 15 (436 mg, 46% yield) as a yellow solid.

[0089] 1 H NMR(400MHz,Chloroform-d)δ7.34(s,1H),7.28(d,J=2.1Hz,1H),7.26–7.22(m,1H),7.09(d,J=3.7Hz,2H),7.07(s,1H ),7.03(dd,J=8.4,2.2Hz,1H),2.70(t,J=7.8Hz,4H),1.74(q,J=7.3Hz,4H),1.39–1.24(m,32H),0.88(t,J=6.6Hz,6H). 13 C NMR(101MHz,Chloroform-d)δ160.7,158.2,143.0,142.8,142.7,142.4,141.4, 141.4,138.7,138.4,135.0,133.5,133.1,132.8,132.6,132.1,132.1,131.1,1 31.0,130.8,130.6,130.6,130.4,125.9,124.5,124.0,123.7,119.5,119.3,32.0,29.9,29.9,29.8,29.7,29.7,29.7,29.7,29.5,29.5,28.6,28.6,22.8,14.2.

[0090]

[0091] Under a nitrogen atmosphere, triphenylphosphine (PPh3, 10.26 g, 39.10 mmol) was added to a solution of compound 15 (1.86 g, 1.96 mmol) in o-dichlorobenzene (ODCB, 8.5 mL). The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the mixture was rapidly passed through a silica gel column using dichloromethane as the eluent to give a dark red solid crude cyclized product. To avoid oxidation, the crude product was not further purified, but was directly mixed under a nitrogen atmosphere with potassium carbonate (K₂CO₃, 696 mg, 5.04 mmol), potassium iodide (KI, 836 mg, 5.04 mmol), 2-butyl-1-bromooctane (1.26 g, 5.04 mmol), and anhydrous N,N-dimethylformamide (DMF, 15.0 mL). This mixture was stirred at 100 °C for 3 hours. After cooling to room temperature, the reaction was quenched with water and extracted three times with petroleum ether. The organic layer was concentrated under reduced pressure to give a pale yellow solid crude alkylated product. To avoid oxidation, the crude product was not further purified; instead, phosphorus oxychloride (0.6 mL) was added directly to a solution of the crude alkylated product (635 mg, 0.52 mmol) and N,N-dimethylformamide (DMF, 0.6 mL) in 1,2-dichloroethane (DCE, 30 mL) under argon protection. The resulting mixture was stirred and refluxed for 12 hours, then cooled to 0 °C. The mixture was slowly added to a saturated sodium acetate solution (40 mL), and then stirred at room temperature for 2 hours. The resulting mixture was extracted with dichloromethane, and the organic layer was dried over anhydrous sodium sulfate for 1 hour. After solvent removal, the crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (1:1 v / v) as eluent to give a yellow solid compound 16 (478 mg, 72% yield).

[0092] 1 H NMR(400MHz,Chloroform-d)δ10.14(d,J=11.9Hz,2H),7.25–7.18(m,2H),7.01(d,J=8.6Hz,1H),4.57(dd,J=19.8,7.8Hz,4H ),3.16(dt,J=20.1,7.7Hz,4H),1.95(ddt,J=63.3,17.2,7.3Hz,7H),1.45–1.24(m,36H),1.06–0.85(m,32H),0.66(m,13H). 13CNMR(101MHz,Chloroform-d)δ182.0,146.8,146.7,144.3,143.6,139.2,138.0,137.5,137.3,133.2,130.7,130.1,129.2,128.6,12 7.8,126.4,125.5,123.0,55.0,38.7,31.9,31.6,30.4,30.2,29.6,29.5,29.4,29.4,28.1,27.9,25.2,22.8,22.5,14.2,14.0,13.7.

[0093]

[0094] Under argon protection, compound 16 (128 mg, 0.1 mmol), dicyandiamide (115 mg, 0.5 mmol), and 10 mL of dry chloroform were added to a 100 mL double-necked round-bottom flask. Then, 0.2 mL of pyridine was added dropwise to the mixture. The reaction mixture was stirred at 70 °C for 12 hours. After cooling to room temperature, the reaction mixture was poured into 70 mL of methanol to precipitate. The precipitate was purified by silica gel column chromatography using petroleum ether / chloroform (v / v 4:5) as eluent to give the black target compound 4 (151 mg, 89% yield).

[0095] 1 H NMR(400MHz,Methylene Chloride-d2)δ9.14(d,J=13.2Hz,2H),8.56(ddd,J=10.1,6.6,5.1Hz,2H),7.71(td,J=7. 6,5.7Hz,2H),7.31–7.25(m,2H),7.09(dd,J=8.6,2.2Hz,1H),4.73(dd,J=21.7,7.9Hz,4H) ,3.20(dt,J=21.4,7.8Hz,4H),2.11(dd,J=12.7,6.2Hz,2H),1.82(ddd,J=20.9,14.8,7.8H z,4H),1.54(m,8H),1.40–0.80(m,62H),0.73–0.62(m,12H).HR-MS(m / z,MALDI):Calc.for C96H105Cl2F5N6O2S5[M+],1700.6307; found:1700.6195.

[0096] Example 2

[0097] This embodiment provides a test for ultraviolet-visible absorption spectroscopy.

[0098] The organic photoelectric compounds prepared in Example 1 were formulated into 10... -5 mol / L and 10 -2 A mol / L chloroform solution was used for measuring the UV-Vis absorption in solution, while the solution was spun onto a quartz plate at 1200 rpm to measure the UV-Vis absorption of the thin film. The scanning range for both was 300–1000 nm, and the measuring instrument was a Jasco V-570UV / VIS / NIR Spectrophotometer. The testing methods for the compounds were consistent.

[0099] The UV-Vis absorption spectra of compounds 1–4 are as follows: Figure 1 As shown, the compound exhibits strong absorption in the solution range of 600–900 nm, with the maximum absorption peak located between 700 and 800 nm. In contrast, the thin-film absorption shows a significant red shift and a wider absorption range, with the maximum absorption peak located between 750 and 850 nm. When blended with a spectrally complementary wide-bandgap donor material, it can achieve high photoelectric conversion efficiency in photovoltaic devices. It is evident that the compound exhibits wide and strong UV-Vis absorption in both solution and thin-film states, which contributes to the effective absorption of sunlight, thereby achieving a high short-circuit current density.

[0100] Example 3

[0101] This embodiment provides the fabrication and testing of a solar cell device using electron acceptors as raw materials.

[0102] Conventional devices based on donor D18:non-fullerene acceptors (NFAs) are fabricated using an ITO / 2PACz / D18:NFAs / PNDIT-F3N / Ag structure. The specific steps are as follows:

[0103] First, glass substrates coated with indium tin oxide (ITO) were sequentially immersed in a detergent solution, deionized water, acetone, and isopropanol, and ultrasonically cleaned for 15 minutes in each solution, followed by drying with nitrogen. Before use, the cleaned ITO substrates were subjected to UV exposure for 15 minutes in a UV ozone chamber (Jellyat). Next, (2-(9H-carbazole-9-yl)ethylphosphonic acid (2PACz) was spin-coated onto the ITO substrate at 3000 rpm for 20 seconds. The substrates were then dried in air at 100°C for 10 minutes. Afterward, the substrates were transferred to a nitrogen-filled glove box. Then, D18:NFAs (donor to acceptor ratio of 1:1) was completely dissolved in chloroform (CF) at a donor concentration of 4.0 mg / mL and spin-coated onto the 2PACz layer at 2000 rpm for 30 seconds. After spin-coating, the mixed film was annealed at 90°C for 5 minutes. The optimal active layer thickness is approximately 100 nm. PNDIT-F3N (dissolved at a concentration of 1 mg / mL in methanol containing 0.5% (v / v) glacial acetic acid) is then spin-coated onto the active layer at 3000 rpm for 20 seconds. Finally, [the coating process is described in 2×10⁻⁶]. -6 A 150 nm thick silver electrode was deposited under vacuum conditions. The active area of ​​the device is 4 mm². A mask with an area of ​​3.24 mm² was used for current-voltage (JV) testing.

[0104] The photoelectric parameters of the solar cell devices prepared using compounds 1-4 as electron acceptor materials and D18 as donor material are shown in Table 1.

[0105] Table 1 Solar Cell Performance

[0106]

[0107] Solar cells prepared using compounds 1 to 4 as electron acceptor materials can all achieve high energy conversion efficiency.

[0108] In summary, monolayer bulk heterojunction solar cell devices prepared using the compounds of this application as electron acceptor materials all exhibit high photoelectric conversion efficiencies, with the highest photoelectric conversion efficiency reaching 19%. Furthermore, the compounds of this invention possess precise molecular weights, easily tunable molecular structures, and are readily purified, making them suitable for preparing high-performance organic solar cells with high open-circuit voltages, good stability, flexibility, and large area.

[0109] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0110] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An electron acceptor containing a sulfur-bridging central unit, characterized in that, Its structural formulas are shown in equations (2) to (4); Equation (2) Equation (3) Equation (4).

2. The method for preparing the electron acceptor of the sulfur-containing bridging central unit according to claim 1, characterized in that, Includes the following steps: The dialdehyde compound, the precursor compound with an electron-deficient terminal group, the organic solvent and the catalyst were mixed and reacted for 24 hours. The mixture was extracted, the organic phases were combined, dried, the solvent was removed, and the mixture was separated by column chromatography to obtain the electron acceptor of the sulfur-containing bridging central unit. The structural formulas of the dialdehyde compounds are shown in Formulas 11, 14, and 16. Formula 11 Formula 14 Formula 16 The precursor compound with the electron-deficient terminal group is selected from compound 11; compound 11 is: ； The organic solvent is any one of chloroform, dichloromethane, and tetrahydrofuran; The catalyst is any one of triethylamine, piperidine, pyridine, ammonium acetate, ammonium propionate, and ammonium butyrate.

3. The preparation method according to claim 2, characterized in that, The ratio of the organic solvent to the dialdehyde compound is 10-20:1, expressed in L / mol. And / or, the molar ratio of the catalyst to the dialdehyde compound is 1:

5.

4. The preparation method according to claim 2 or 3, characterized in that, The preparation method of the dialdehyde compound includes the following steps: The intermediate donor compound, phosphorus oxychloride, anhydrous N,N-dimethylformamide, and a haloalkane organic solvent were mixed and reacted for 6–24 hours. Then, a saturated sodium acetate aqueous solution was added, and the reaction was carried out at room temperature for 0.5–2 hours. The mixture was extracted, the organic phases were combined, dried, the solvent was removed, and the mixture was separated by column chromatography to obtain the dialdehyde compound. The structural formulas of the intermediate donor compounds are shown in Formulas 10 and 13. Formula 10 Formula 13.

5. The preparation method according to claim 4, characterized in that, The halogenated alkane organic solvent is any one of chloroform, dichloromethane, and 1,2-dichloroethane; And / or, in L / mol, the ratio of the haloalkane organic solvent to the intermediate donor is 10~20:1; And / or, the molar ratio of the intermediate donor, the phosphorus oxychloride, and the anhydrous N,N-dimethylformamide is 1:5:

10.

6. The preparation method according to claim 4, characterized in that, The method for preparing the intermediate donor includes the following steps: The precursor compound was subjected to a cyclization reaction with triphenylphosphine, followed by a one-pot substitution reaction with 3-(bromomethyl)heptane to obtain the intermediate donor. The structural formulas of the precursor compounds are shown in Formula 9 and Formula 12. Formula 9 Equation 12.

7. The application of the electron acceptor of the sulfur-containing bridging central unit as described in claim 1 in organic optoelectronic devices.

8. An organic optoelectronic device, characterized in that, The electron acceptor of the sulfur-containing bridging central unit as described in claim 1 is used as its active layer material.

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