Compound formed by coupling asymmetric Y-series receptor and fluorene as well as preparation method and application of compound

Abstract

The invention relates to the technical field of photoelectric materials, in particular to an asymmetric Y-series receptor and fluorene coupled compound and a preparation method and application thereof. The invention provides a fluorenyl-cyclic structure-asymmetric Y6 ternary fusion structure with a clear structure-function relationship. The rigid plane structure of fluorene provides excellent hole transport capability and inherent thermal form stability for molecules. The asymmetric Y6 can effectively regulate and control the energy level structure of molecules and enhance intramolecular charge transfer, and meanwhile, the asymmetric structure of the asymmetric Y6 is beneficial to inhibition of excessive crystallization and optimization of phase separation. The combination of the two can generate a synergistic effect. The fluorene unit can compensate voltage loss caused by introduction of bromine, and realizes wider spectral absorption and higher charge generation and transmission efficiency through combined action. A cyclic structure is introduced into a fluorene core, so that the LUMO energy level of the whole molecular receptor is effectively increased. The compound as an acceptor material is excellent in performance, has a three-dimensional charge transfer characteristic, and is beneficial to improvement of charge mobility.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic materials technology, and in particular to an asymmetric Y-series acceptor coupled with fluorene, its preparation method and application. Background Technology

[0002] Organic solar cells (OSCs) have become an important development direction for next-generation photovoltaic technology due to their outstanding advantages such as light weight, flexibility, solution-processability, and suitability for fabricating large-area devices. In recent years, OSCs have achieved breakthroughs in photoelectric conversion efficiency, mainly thanks to the successful development of non-fullerene acceptors (NFAs), particularly A-DA'DA type fused-ring electron acceptors represented by Y6 and its derivatives. These acceptor materials possess strong and broad near-infrared absorption, tunable energy levels, and favorable molecular packing characteristics, driving continuous improvement in the efficiency of single-junction OSCs.

[0003] However, key challenges remain in moving OSCs from laboratory research to practical applications and commercialization: First, further improvements in efficiency require overcoming the open-circuit voltage (V). OC ) and short-circuit current density (J SC The interrelationship between V and fill factor (FF) and how to effectively improve V while maintaining strong light absorption capacity. OC This is one of the core challenges. Secondly, the molecular aggregation behavior of the active layer material is difficult to precisely control, easily leading to excessive aggregation or excessively large phase region sizes, resulting in severe charge recombination and low transport efficiency, thus limiting the improvement of FF (Functional Filter). Furthermore, active layers prepared from small molecule materials typically lack sufficient thermodynamic and morphological stability, making them prone to phase separation and coarsening under long-term device operation or thermal stress, leading to performance degradation and affecting device lifespan. Finally, the solubility and film-forming properties of the material directly affect its compatibility with large-area printing processes (such as blade coating and inkjet printing), representing a processing problem that must be solved for industrialization. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a compound coupled with an asymmetric Y-series receptor and fluorene, along with its preparation method and applications.

[0005] The first objective of this invention is to provide a compound coupled with an asymmetric Y-series receptor and fluorene, the structural formula of which is shown in Formula I:

[0006] In Formula I, n can be 1-10; R1 can be H, a straight-chain alkyl group of C6-C18 or a branched alkyl group of C6-C39 independently; R2 can be independently a straight-chain alkyl group of C6-C18 or a branched alkyl group of C6-C39.

[0007] Furthermore, R1 and R2 are (-C 11 H 23 -(CH2)CH(C6H) 13 (C8H) 17 -(CH2)CH(C8H) 17 (C) 10 H 21 ) or -(CH2)CH(C 10 H 21 (C) 12 H 25 ).

[0008] Furthermore, when n is 2, the compound shown in Formula I is specifically: .

[0009] A second objective of this invention is to provide a method for preparing the asymmetric Y-series acceptor coupled with fluorene as described above, comprising the following steps: 1) Using 2,7-dibromofluorene as a starting material, the compound shown in Formula II1 was obtained by alkylation reaction: ; 2) Using n-butyllithium as a nucleophile, a rapid metal-halogen exchange reaction occurs with the compound shown in formula II2. The newly generated organolithium reagent then acts as a nucleophile, undergoing an SN2-type substitution reaction to yield the compound shown in formula II2. ; 3) Compound III3 is obtained by coupling reaction of the compounds shown in Formula III1 and Formula III2 with a palladium dichloride catalyst catalyzed by bis(triphenylphosphine): ; 4) Using triphenylphosphine as a reducing agent and K2CO3 as a base, the product of the reduction cyclization of the compound shown in formula III3 and the compound shown in formula III4 undergo a nucleophilic substitution reaction to give the compound shown in formula III5: ; 5) The compound shown in Formula III5 undergoes a formylation reaction with phosphorus oxychloride to produce the compound shown in Formula III6: ; 6) Compounds of Formula III7 and III8 are capped with compound of Formula III6 via a Knoevenagel condensation reaction to obtain compound of Formula III9: ; 7) The compound shown in Formula II2 and the compound shown in Formula III9 undergo a Stille coupling reaction catalyzed by tris(dibenzylidene indacetone)dipalladium(O) and tris(o-methylphenyl)phosphine to give the compound shown in Formula I.

[0010] Furthermore, the reaction described in step 1) is carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: Compounds 2,7-dibromofluorene and 1,3-dibromopropane, along with potassium hydroxide, are added sequentially to a round-bottom flask equipped with a magnetic stir bar. The mixture is evacuated and purged with nitrogen, and this process is repeated three times. Then, solvent DMSO is added to the flask, and the reaction is carried out at room temperature for 8-24 hours. After the reaction is complete, the remaining base and reactive intermediates are quenched. The reaction solution is added to a 10% sodium thiosulfate aqueous solution and stirred for 1 hour. The solution is extracted with ethyl acetate and washed with deionized water and saturated brine. The organic phase is dried over anhydrous sodium sulfate and the solvent is removed by rotary evaporation. The crude product is purified by silica gel column chromatography to obtain the compound shown in formula II1.

[0011] Furthermore, the reaction in step 2) is carried out at a temperature of -78 to 0 °C for 2 to 24 hours. The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: Compound II1 is added to a round-bottom flask equipped with a magnetic stir bar. The mixture is evacuated and purged with nitrogen, and this process is repeated three times. Then, tetrahydrofuran solvent is added to the flask, and the temperature is lowered to -78 °C. Butyllithium is added dropwise to the reaction flask, and the mixture is heated to room temperature for 30 minutes. The temperature is then lowered to -78 °C, and trimethyltin chloride is slowly added. The mixture is then allowed to warm to room temperature overnight. After the reaction is complete, the reaction is quenched with deionized water, extracted with dichloromethane, and the organic phase is dried with anhydrous sodium sulfate. The solvent is removed by rotary evaporation. After rotary evaporation, the system is recrystallized by adding a small amount of dichloromethane and methanol, freezing the mixture, and allowing it to stand for a period of time until the solid precipitates. After recrystallization, the product is filtered and washed to obtain compound II2. The reaction in step 3) is carried out at a temperature of 80-120 °C for 6-48 h. The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: Compound 4,7-dibromo-5,6-dinitrobenzo[C][1,2,5]thiadiazole and tributyl(6-undecylthienro[3,2-B]thien-2-yl)tinane are added to a round-bottom flask equipped with a magnetic flask. Then, palladium dichloride of bis(triphenylphosphine) chloride is weighed, the mixture is evacuated and purged with nitrogen, and this process is repeated three times. Toluene, the solvent, is added to the reaction flask, and the reaction proceeds at 110 °C. oHeating at C for 12 hours; after the reaction was complete, cooling to room temperature, quenching with deionized water, and extracting the mixture with dichloromethane; drying the organic layer with anhydrous sodium sulfate and concentrating under reduced pressure to remove the solvent, and then purifying the crude product by rapid column chromatography to obtain a red solid, namely the compound shown in formula III3; The reaction in step 4) is carried out at a temperature of 40-100 °C for 6-48 h. The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: under nitrogen atmosphere, triphenylphosphine and KI are dissolved in NMP and stirred for 10 min; the compound shown in Formula III3 is added, and the temperature is raised to 70°C. o React at C for 2 hours; then cool to 50°C. o C. Add KOH powder in batches; add NMP solution of the compound shown in Formula III4 dropwise, and heat to 85°C. o After the reaction was completed at step C for 8 hours, it was quenched by slowly adding ice water. The mixture was extracted with ethyl acetate, the organic layers were combined, dried on MgSO4 and concentrated under reduced pressure to remove the solvent. The mixture was then purified by column chromatography on silica gel to obtain a red solid, which is the compound shown in formula III5.

[0012] Furthermore, the temperature of the reaction described in step 5) can be 0~100 ℃; the time can be 2-20 h; The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: DMF is added to the reaction flask, and the mixture is cooled to 0°C in an ice bath. o C; Slowly add phosphorus oxychloride dropwise, stirring for 30 minutes; Add the compound shown in formula III5 in batches, maintaining 0 o Stir for 30 minutes, remove from ice bath, and stir for 1 hour at room temperature; heat oil bath to 80°C. o C. Stir for 6 hours. After the reaction is complete, quench the reactants and cool the reaction solution in an ice bath to 0°C. o C. Slowly pour into the ice-water mixture, then add saturated NaOAc solution to adjust the pH to neutral, extract with ethyl acetate, combine the organic phases, wash the organic phase with deionized water and saturated brine; dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and purify by column chromatography on silica gel to obtain a red solid, namely the compound shown in formula III6. The reaction in step 6) is carried out at a temperature of 50-100 °C for 2-20 h. The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: Compounds of formulas III6, III7, and III8 are added to a round-bottom flask equipped with a magnetic stir bar. The mixture is evacuated and purged with nitrogen gas, repeated three times. Then, chloroform is added to the reaction flask, stirred until completely dissolved, pyridine is added, and the mixture is heated to 65°C. o C, react overnight; after the reaction is complete, cool to room temperature, quench with deionized water, and extract the mixture with dichloromethane and wash twice with water; the organic layer is dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent, and then the crude product is purified by silica gel column chromatography to obtain the compound shown in product formula III9; The reaction temperature described in step 7) can be 90~120 °C, specifically 110 °C; the time can be 6-48 h, specifically 12 h. The reaction was carried out under a nitrogen atmosphere; The specific operation of the reaction is as follows: Compounds of Formula II2 and Formula III9, tris(dibenzylindeneacetone)dipalladium, and tris(o-methylphenyl)phosphine are added to a round-bottom flask equipped with a magnetic stir bar. The mixture is evacuated and purged with nitrogen, and this process is repeated three times. Then, anhydrous toluene is added to the reaction flask, and the reaction proceeds at 110 °C. o Heating at C for 12 hours; after the reaction was complete, cooling to room temperature, the crude product was purified by silica gel column chromatography to obtain a black solid product, namely the compound shown in Formula I.

[0013] Furthermore, the molar ratio of 2,7-dibromofluorene to 1,3-dibromopropane is 1:1-6, and the molar ratio of 2,7-dibromofluorene to potassium hydroxide is 1:4-6. The molar ratio of the compound shown in Formula II1 to n-butyllithium is 1:2-2.5, and the molar ratio of the compound shown in Formula II1 to trimethyltin chloride is 1:2-2.5. The molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole to tributyl(6-undecylthienro[3,2-B]thien-2-yl)stanane is 1:2.2-2.5, and the molar ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole to bis(triphenylphosphine)palladium dichloride is 1:0.05-0.1. The molar ratio of the compound shown in Formula III3 to the compound shown in Formula III4 is 1:2.2-2.5; the molar ratio of the compound shown in Formula III3 to triphenylphosphine is 1:0.05-0.1; the molar ratio of the compound shown in Formula III3 to KOH and KI is 1:2-3:1-1.5. The molar ratio of the compound shown in Formula III5 to phosphorus oxychloride is 1:1.5-2.5; The molar ratio of the compounds shown in Formulas III6, III7, and III8 can be 1: 1-1.3: 1-1.3; The molar ratio of the compounds shown in Formula II2 and Formula III9 is ​​1:2; the molar ratio of the compound shown in Formula II2 to tris(dibenzylidene indeneacetone)dipalladium and tris(o-methylphenyl)phosphine is 1:0.06:2.4.

[0014] A third objective of this invention is to provide an active layer for an organic solar cell device, wherein the donor material is D18, the acceptor material is L8-BO and a compound coupled with fluorene and an asymmetric Y-series acceptor as described above, with a mass ratio of 1:1:0.1.

[0015] A fourth objective of the present invention is to provide an organic solar cell device comprising, in sequence, an ITO substrate, a PEDOT:PSS layer, an active layer as described above, PDINN, and an Ag electrode.

[0016] This invention provides a fluorene-cyclic-asymmetric Y6 ternary fusion structure with a clear structure-property relationship. The structure achieves a performance breakthrough through the following synergistic effects: (1) The strain effect of the cyclic structure, such as the four-membered ring, can reconstruct the electron cloud distribution of the fluorene nucleus, generate a significant electron-donating effect, enhance the acceptor LUMO energy level, and significantly improve the open-circuit voltage while maintaining strong near-infrared absorption; (2) The three-dimensional conformation can effectively inhibit excessive molecular aggregation, induce the formation of an ideal nanoscale phase separation morphology, and provide an optimized pathway for charge transport; (3) The retained bromine reaction sites provide the possibility of constructing a cross-linked network, significantly improving thermal stability and morphological stability.

[0017] At the application level, its tunable energy level makes it an ideal choice for tandem solar cells, capable of breaking through the efficiency limit of single-junction cells. At the industrialization level, its excellent solution processability and cross-linking stability are compatible with large-area printing processes. This research not only provides a new material platform for OSCs, but also pioneers a new paradigm for performance optimization through tension engineering and three-dimensional conformational control, which has significant implications for emerging fields such as flexible electronics and building-integrated photovoltaics.

[0018] The present invention has the following advantages: The rigid planar structure of fluorene provides the molecule with excellent hole transport capabilities and inherent thermal stability. The bromine atom in the asymmetric Y6 molecule acts as a powerful electron-withdrawing group and reaction site, effectively modulating the molecular energy level structure and enhancing intramolecular charge transfer. Simultaneously, its asymmetric structure helps suppress over-crystallization and optimize phase separation. The combination of these two elements produces a synergistic effect. The fluorene unit can compensate for the voltage loss caused by the introduction of bromine, working together to achieve broader spectral absorption and higher charge generation and transport efficiency.

[0019] Introducing a ring structure into the fluorene nucleus is a revolutionary modification of the classic fluorene framework. This is not merely adding a ring, but introducing significant ring strain and geometric distortion. High ring strain significantly alters the electron cloud distribution of the fluorene nucleus, generating a powerful electron-donating effect and effectively raising the LUMO energy level of the entire molecular acceptor.

[0020] The compounds of this invention, which are asymmetric Y-series acceptors coupled with fluorene, exhibit excellent acceptor material properties and three-dimensional charge transport characteristics, contributing to improved charge mobility. The ternary device based on compound D18:L8-BO:Y4Y achieves a PCE of 19.82% and a fill factor FF of 82.40%. Attached Figure Description

[0021] Figure 1 This is a chemical synthesis flowchart of the compound shown in Formula I in Example 1 of the present invention; Figure 2 The compound of formula II1 prepared in this invention 1 H NMR spectrum; Figure 3 The compound of formula II1 prepared in this invention 13 C NMR spectrum; Figure 4 The compound of formula I prepared in Example 1 of this invention 1 H NMR spectrum; Figure 5 The HRMS spectrum of the compound of formula I prepared in Example 1 of this invention; Figure 6 The UV-Vis spectra of the compound of formula I prepared in Example 1 of this invention in solution and thin film (f) are shown. Figure 7 The current density-voltage (JV) test graphs of the binary and ternary organic solar energy devices prepared in this invention are shown. Figure 8 The external quantum efficiency (EQE) test results are shown for the binary and ternary organic solar energy devices prepared according to this invention. Detailed Implementation

[0022] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0024] Unless otherwise specified, the "water" used in the following examples is deionized water.

[0025] In the following tests of this invention, proton nuclear magnetic resonance (NMR) spectra were performed on an AVANCE NEO 400MHz NMR spectrometer from Bruker GmbH, Germany. The solvent used was deuterated chloroform (CDCl3), and the instrument was calibrated with tetramethylsilane (TMS).

[0026] The Y4Y receptor molecule provided by this invention has the structural formula shown in Formula I:

[0027] The present invention also provides the application of the compound shown in Formula I as an organic solar cell acceptor material, specifically the application of the compound shown in Formula I in the preparation of organic solar cell devices.

[0028] This invention also provides an organic solar cell device and a method for its fabrication.

[0029] The organic solar cell device provided by this invention uses the compound shown in Formula I above as the acceptor material.

[0030] The binding strategy of fluorene with the asymmetric Y6 acceptor provided by this invention not only achieves a more stable and efficient active layer morphology, significantly reducing efficiency loss, but also significantly improves the device's lifetime, representing a crucial step towards commercialization. This combination represents a proactive exploration of synergistically addressing the core contradictions of efficiency, stability, and processability through sophisticated molecular design, opening up an attractive material platform for developing next-generation high-performance, long-lifetime, solution-processable organic solar cells.

[0031] Example 1: The chemical synthesis flowchart of the compound shown in Formula I is as follows. Figure 1 As shown, the specific reaction conditions are as follows: (1) Synthesis of the compound shown in formula II1 and the compound shown in formula II2 in steps 1-2: The synthetic steps of the compound shown in Formula II1 are as follows: In a round-bottom flask equipped with a magnetic stir bar, compounds 2,7-dibromofluorene (5 g, 15.4 mmol) and 1,3-dibromopropane (3.11 g, 15.4 mmol), and potassium hydroxide (3.45 g, 61.6 mmol) were added sequentially. The mixture was evacuated and purged with nitrogen, and this process was repeated three times. Then, 20 mL of DMSO solvent was added to the flask, and the reaction was carried out at room temperature for 12 hours. After the reaction was complete, the remaining base (KOH) and reactive intermediates were quenched. The reaction solution was added to a 10% sodium thiosulfate aqueous solution (volume ≈ 1.5 times the volume of the reaction solution), and stirred for 15 minutes. The mixture was extracted three times with ethyl acetate, washed twice with deionized water, and washed once with saturated brine (NaCl). The organic phase was dried over anhydrous sodium sulfate and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography using pure petroleum ether as the eluent to give a white powder compound, namely the compound shown in Formula II1. 1 The H NMR spectrum is shown in [reference]. Figure 2 ,That 13 The C NMR spectrum is shown below. Figure 3 .

[0032] The structural verification data is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 7.87 (s, 2H), 7.47 (q, J = 8.0 Hz, 4H), 2.62 (t, J = 7.9 Hz, 4H), 2.39 (p, J = 7.6 Hz, 2H); 13 C NMR (101 MHz, Chloroform-d) δ 153.91, 137.32, 130.30, 126.22, 121.67, 120.91, 51.99, 32.99,16.84. As can be seen from the above, the structure of the product is correct.

[0033] The synthetic steps of the compound shown in Formula II2 are as follows: The compound shown in Formula II1 (416 mg, 1.14 mmol) was added to a round-bottom flask equipped with a magnetic stir bar. The mixture was evacuated and purged with nitrogen, and this process was repeated three times. Then, tetrahydrofuran (30 mL) was added to the flask, and the mixture was cooled to -78 °C. Butyllithium (1.78 mL, 2.85 mmol) was added dropwise to the reaction flask. The mixture was heated to room temperature and reacted for 30 min. Then, the temperature was lowered to -78 °C, and trimethyltin chloride (2.51 mL, 2.51 mmol) was slowly added. The mixture was then allowed to warm to room temperature overnight. After the reaction was complete, the reaction was quenched with deionized water (10 mL), extracted with dichloromethane (30 mL × 3), and the organic phase was dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation. After drying, the system was recrystallized by adding a small amount of dichloromethane and methanol, freezing the mixture, and allowing it to stand for a period of time to allow the solid to precipitate. After recrystallization, the product was filtered and washed to obtain the compound shown in formula II2.

[0034] (2) Synthesis of the compounds shown in formulas III3, III5, III6 and III9 in steps 3-6: The synthetic steps of the compound shown in Formula III3 are as follows: In a round-bottom flask fitted with a magnetic stir bar, compound 4,7-dibromo-5,6-dinitrobenzo[C][1,2,5]thiadiazole (2.1 g, 5.51 mmol) and tributyl(6-undecylthieno[3,2-B]thieno-2-yl)stanane (7.5 g, 12.84 mmol) were added, followed by the weighing of palladium dichloride bis(triphenylphosphine) (386 mg, 0.56 mmol). The mixture was evacuated and purged with nitrogen, and the reaction was repeated three times. Toluene (60 mL) was added to the reaction flask, and the mixture was heated to 110 °C for 12 hours. After the reaction was complete, it was cooled to room temperature, quenched with deionized water (10 mL), and the mixture was extracted with dichloromethane (30 mL × 3). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was then purified by rapid column chromatography using petroleum ether (60-90 °C) / dichloromethane = 5 / 1 as the eluent to give a red solid, namely the compound shown in formula III3.

[0035] The synthetic steps of the compound shown in Formula III5 are as follows: Under nitrogen atmosphere, triphenylphosphine (581 mg, 2.22 mmol) and KI (459 mg, 2.78 mmol) were dissolved in NMP and stirred for 10 min. The compound shown in Formula III3 (1.5 g, 1.85 mmol) was added, and the mixture was heated to 70 °C for 2 h. The temperature was lowered to 50 °C, and KOH powder (207 mg, 3.69 mmol) was added in portions. A solution of 1-bromo-2-octyldodecane (the compound shown in Formula III4) (1.46 g, 4.07 mmol) in NMP was added dropwise, and the mixture was heated to 85 °C for 8 h. After the reaction was complete, it was quenched by slowly adding ice water (10 times its volume). The mixture was extracted with ethyl acetate (30 mL × 3), the organic layers were combined, dried over anhydrous MgSO4, concentrated under reduced pressure to remove the solvent, and purified by column chromatography on silica gel using dichloromethane / petroleum ether (1 / 10, v / v) as the eluent to obtain a red solid, namely the compound shown in Formula III5.

[0036] The synthetic steps of the compound shown in Formula III6 are as follows: Add DMF (128 mg, 1.74 mmol) to the reaction flask and cool to 0 °C in an ice bath. Slowly add phosphorus oxychloride (354 mg, 2.31 mmol) dropwise while stirring for 30 minutes. Add the compound shown in Formula III5 (1.5 g, 1.16 mmol) in portions while maintaining stirring at 0 °C for 30 minutes. Remove the ice bath and allow to reach room temperature, stirring for 1 hour (the solution turns deep red / brown). Heat in an oil bath to 80 °C and stir for 6 hours. After the reaction is complete, quench the reactants, cool the reaction mixture to 0 °C in an ice bath, and slowly pour it into an ice-water mixture (10 times the volume). Then, adjust the pH to neutral by adding saturated NaOAc solution, extract with ethyl acetate (3 × 30 mL), combine the organic phases, wash twice with 50 mL of deionized water, and wash once with 20 mL of saturated brine. Dry the organic phase with anhydrous sodium sulfate and remove the solvent by rotary evaporation. The compound was purified by column chromatography on silica gel using petroleum ether / dichloromethane (1 / 1, v / v) as the eluent to obtain a red solid, namely the compound shown in Formula III6.

[0037] The synthetic steps of the compound shown in Formula III9 are as follows: In a round-bottom flask equipped with a magnetic stir bar, add compounds of formula III6 (1 g, 0.73 mmol), 5,6-difluoro-3-(dicyanomethylene)indophenone (compound shown in formula III7) (276 mg, 0.95 mmol), and 2-(5-bromo-4-fluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile (compound shown in formula III8) (219 mg, 0.95 mmol). Vacuum the mixture and purge with nitrogen, repeating this process three times. Then, add 150 mL of chloroform solvent to the reaction flask, stir until completely dissolved, add pyridine (3 mL), and heat to 65 °C. React overnight. After the reaction is complete, cool to room temperature, quench with 10 mL of deionized water, and extract the mixture with 30 mL × 3 of dichloromethane, washing twice with water. The organic layer is dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was then purified by silica gel column chromatography using petroleum ether (60-90 °C) / dichloromethane (4 / 1, v / v) as the eluent to give the product shown in formula III9.

[0038] (3) Perform the synthesis of the compound shown in Formula I in step 7: The synthetic steps of the compound shown in Formula I are as follows: The specific procedure for the reaction is as follows: In a round-bottom flask equipped with a magnetic stir bar, add compound II2 (13 mg, 0.025 mmol), compound III9 (100 mg, 0.05 mmol), tris(dibenzylindeneacetone)palladium (1.4 mg, 0.0015 mmol), and tris(o-methylphenyl)phosphine (1.8 mg, 0.06 mmol), evacuate the flask, and purge with nitrogen. Repeat this process three times. Then, add anhydrous toluene (20 mL) to the reaction flask, and heat to 110 °C. o The mixture was heated to C and reacted for 12 hours. After the reaction was complete, it was cooled to room temperature, and the crude product was purified by silica gel column chromatography to obtain a black solid product, namely the compound shown in Formula I. The compound shown in Formula I... 1 The H NMR spectrum is shown in [reference]. Figure 4 Its high-resolution mass spectrometry (HRMS) spectrum is as follows: Figure 5 As shown, the molecular weight is completely consistent with the isotope peaks of the elements and the theoretical molecular weight and isotope peaks of the compounds.

[0039] The structural verification data is as follows: 1H NMR (400 MHz, Chloroform-d) δ 9.23 (s, 2H), 9.16 (s, 2H), 8.67 (d,J = 7.8 Hz, 2H), 8.60 – 8.52 (m, 2H), 8.15 (s, 2H), 8.01 (t, J = 7.5 Hz, 2H), 7.91 (d, J = 7.7 Hz, 2H), 7.69 (d, J = 8.2 Hz, 4H), 4.76 (d, J = 7.9 Hz, 8H), 3.25 (dd, J = 14.8, 7.8 Hz, 8H), 2.81 (t, J = 7.7 Hz, 4H), 2.53 (s, 2H), 2.13(s, 4H), 1.97 – 1.82 (m, 8H), 1.58 – 0.60 (m, 228H). As can be seen from the above, the structure of the product is correct.

[0040] Example 2: Fabrication and Characterization of Organic Solar Cell Devices First, the substrate was cleaned by rubbing the ITO-coated glass substrate with detergent water. Then, it was ultrasonically treated for 30 minutes each in deionized water, ethanol, acetone, and ethanol solvents. After ultrasonication, the substrate was dried with nitrogen gas and then treated in a UV ozone generator for 20 minutes. The UV-treated ITO substrate was then placed on a spin coater. A 1 ml syringe was used to draw PEDOT:PSS solution, which was then evenly dripped onto the substrate surface and spin-coated at 4000 rpm for 30 seconds. The PEDOT:PSS-coated substrate was then placed on a heating stage and annealed at 150 °C for 15 minutes to form a hole transport layer. The substrate with the hole transport layer was then transferred to a glove box.

[0041] Then, donor D18 and acceptor L8-BO were mixed separately to prepare a binary organic solar cell device (the preferred mass ratio of donor and acceptor materials was 1:1). The Y4Y acceptor material prepared in Example 1 (structure shown below) was then used as a third component to dope into the D18:L8-BO binary device to prepare a high-efficiency ternary organic solar cell device (the preferred mass ratio of donor, acceptor, and third component was 1:1:0.1). A blend solution was prepared (total concentration of donor and acceptor was 20 mg / mL), and the blend solution was spin-coated onto a substrate at a spin coating speed of 2000 rpm, resulting in an active layer approximately 130 nm thick on the substrate surface.

[0042] PDINN solution was uniformly dropped onto the surface of the active layer at a speed of 3000 rpm for 30 seconds to form an electron transport layer. Finally, the substrate was transferred to a vacuum evaporator and deposited at a certain rate under a low pressure of 10⁻⁵ Pa to form an electrode of about 100 nm.

[0043]

[0044] Figure 6 The UV-Vis spectra are as follows: The UV-Vis absorption spectra of the solution and the thin film were recorded using a Hitachi U-4100 spectrophotometer, where Y4Y-f refers to the UV-Vis absorption spectrum of the thin film. The solution absorption test sample was dissolved in chloroform at a concentration of 0.01 mg / mL and measured at room temperature. The optical absorption spectrum of the thin film was prepared by spin-coating a chloroform solution (5.0 mg / mL, 1500 rpm) onto a quartz plate. Figure 6 As can be seen, the absorption intensity of compound Y4Y does not change much in solution and film. The maximum absorption peaks in solution and film are located at 737 nm and 795 nm, respectively. Compared with solution, the absorption peak of film is red-shifted by 58 nm, showing weaker aggregation behavior.

[0045] Using a Newport Oriel-Sol3A to simulate AM 1.5G sunlight, the current density versus voltage (JV) curves were obtained through a Keithley 2400, as shown below. Figure 7 As shown, the binary organic solar cell device based on the D18:L8-BO system has a PCE of 18.98% and a fill factor FF of 80.02%, while the ternary device based on the compound D18:L8-BO:Y4Y has a PCE of 19.82% and a fill factor FF of 82.40%. The improvement in the efficiency of organic solar cells is obvious, indicating that the ternary device based on the compound D18:L8-BO:Y4Y has a larger exciton diffusion coefficient and a faster exciton dissociation process.

[0046] External quantum efficiency test graph as shown Figure 8 As shown, the EQE spectrum was analyzed using a certified Newport IPCE measurement system. High-sensitivity EQE was measured using an integrated system (PECT-600, Enlitech), where the photocurrent was amplified and modulated via a locked instrument. After incorporation of compound Y4Y into the acceptor layer, the ternary device based on the D18:L8-BO:Y4Y compound exhibited a significant enhancement in the 450-800 nm range compared to the binary organic solar cell device based on the D18:L8-BO system, with a higher J... SCThis consistency means that Y4Y-based organic solar cell devices have more efficient internal charge transfer and more absorbed photons to generate charge carriers.

[0047] For any points not covered above, existing technologies shall apply.

[0048] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A compound of asymmetric Y series acceptor coupled with fluorene, characterized in that, The structural formula is shown as formula I: In formula I, n can be 1-10; R1 can be independently H, C6-C18 straight chain alkyl or C6-C39 branched chain alkyl; R2 can be independently C6-C18 straight chain alkyl, C6-C39 branched chain alkyl.

2. A compound of asymmetric Y series acceptor coupled with fluorene according to claim 1, characterized in that, R1, R2 are (-C 11 H 23 ), -(CH2)CH(C6H 13 )(C8H 17 ), -(CH2)CH(C8H 17 )(C 10 H 21 ) or -(CH2)CH(C 10 H 21 )(C 12 H 25 ).

3. A compound of asymmetric Y series acceptor coupled with fluorene according to claim 1, characterized in that, When n is 2, the compound shown as formula I is specifically: 。 4. A process for the preparation of a compound of asymmetric Y series acceptor coupled to fluorene as claimed in any one of claims 1 to 3, characterized in that: Comprising the following steps: 1) taking 2,7-dibromofluorene as raw material, obtaining the compound shown as formula II1 through alkylation reaction: ； 2) taking n-butyllithium as nucleophilic reagent, and rapidly carrying out metal-halogen exchange with the compound shown as formula II1, the newly generated organolithium reagent as nucleophilic reagent, and carrying out SN2 type substitution reaction to obtain the compound shown as formula II2 ； 3) the compound shown as formula III1 and the compound shown as formula III2 are coupled under the action of bis-triphenylphosphine palladium dichloride catalyst to obtain the compound shown as formula III3: ； 4) taking triphenylphosphine as reducing agent and K2CO3 as base, carrying out nucleophilic substitution reaction between the product after reduction and cyclization of the compound shown as formula III3 and the compound shown as formula III4 to obtain the compound shown as formula III5: ； 5) carrying out formylation reaction between the compound shown as formula III5 and phosphorus oxychloride to obtain the compound shown as formula III6: ； 6) carrying out Knoevenagel condensation reaction between the compounds shown as formula III7 and formula III8 and the compound shown as formula III6 to obtain the compound shown as formula III9: ； 7) carrying out Stille coupling reaction between the compound shown as formula II2 and the compound shown as formula III9 under the catalysis of tris(dibenzylideneacetone) palladium (0) and tris(o-methylphenyl) phosphorus to obtain the compound shown as formula I.

5. The method of claim 4, wherein: The reaction in step 1) is carried out under nitrogen atmosphere; The specific operation of the reaction is: in a round-bottom flask with a magnetic stirrer, sequentially adding compound 2,7-dibromofluorene, 1,3-dibromopropane and compound potassium hydroxide, evacuating and filling nitrogen, repeating three times; then adding solvent DMSO into the flask, reacting at room temperature for 8-24 h; after the reaction is completed, quenching the remaining base and reactive intermediates; adding the reaction solution into 10% aqueous sodium thiosulfate solution, stirring for 1; extracting with ethyl acetate, washing with deionized water and saturated brine; drying the organic phase with anhydrous sodium sulfate, and removing the solvent by rotary evaporation; purifying the crude product by silica gel column chromatography to obtain the product shown as formula II1.

6. The method of claim 5, wherein: The temperature of the reaction in step 2) is -78~0℃; the time is 2-24 h; The reaction is carried out under nitrogen atmosphere; The reaction is specifically operated as follows: a compound shown as formula II1 is added into a round-bottom flask equipped with a magnet, the mixture is pumped and filled with nitrogen, and the operation is repeated three times; then, a solvent tetrahydrofuran is added into the flask, the temperature is lowered to -78 °C, n-butyl lithium is added into the reaction bottle drop by drop, the temperature is raised to room temperature, and the reaction is performed for 30 min; then, the temperature is lowered to -78 °C, trimethyl tin chloride is slowly added, and then the temperature is naturally raised to room temperature overnight; after the reaction is completed, the reaction is quenched with deionized water, extracted with dichloromethane, and dried with anhydrous sodium sulfate; then, the solvent is removed by using a rotary evaporator; after being dried, the system is recrystallized, that is, a small amount of dichloromethane and methanol is added, and the system is frozen in a refrigerator, and then is left to stand for a period of time, and the solid is precipitated; after recrystallization, the product is filtered and washed to obtain a compound shown as formula II2; The temperature of the reaction in step 3) is 80-120 °C, and the time is 6-48 h; The reaction is performed under a nitrogen atmosphere; The reaction is specifically operated as follows: compound 4,7-dibromo-5,6-dinitrobenzo[C][1,2,5]thiadiazole and tributyl(6-undecylthieno[3,2-B]thiophen-2-yl)stannane are added into a round-bottom flask equipped with a magnetic stirrer, then dichlorobis(triphenylphosphine)palladium is weighed, and the flask is degassed and filled with nitrogen three times; solvent toluene is added into the reaction flask, 110 o C is heated, and the reaction is carried out for 12 hours; after the reaction is completed, it is cooled to room temperature, quenched with deionized water, and the mixture is extracted with dichloromethane; the organic layer is dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent, and then the crude product is purified by flash column chromatography to obtain a red solid, i.e., a compound shown in formula III3; The temperature of the reaction in step 4) is 40-100 °C; and the time is 6-48 h; The reaction is performed under a nitrogen atmosphere; The reaction is specifically operated as follows: triphenylphosphine and KI are dissolved in NMP under nitrogen environment, and stirred for 10 min; the compound shown in formula III3 is added, and the temperature is increased to 70 o C, and the reaction is carried out for 2 hours; the temperature is decreased to 50 o C, KOH powder is added in batches; the NMP solution of the compound shown in formula III4 is added dropwise, the temperature is increased to 85 o C, and the reaction is carried out for 8 hours; after the reaction is completed, quenching is carried out, that is, ice water is slowly added; the mixture is extracted with ethyl acetate, the organic layers are combined, dried over MgSO4, and concentrated under reduced pressure to remove the solvent; column chromatography is carried out on silica gel to purify, and a red solid, that is, the compound shown in formula III5, is obtained.

7. The method of claim 6, wherein: The temperature of the reaction in step 5) can be 0-100 °C; and the time can be 2-20 h; The reaction is performed under a nitrogen atmosphere; The reaction is specifically operated as follows: DMF is added into a reaction bottle, and the temperature is reduced to 0 o C by ice bath; phosphorus oxychloride is slowly added dropwise, and stirred for 30 minutes; the compound shown in formula III 5 is added batch by batch, and stirred for 30 minutes at 0 o C; the ice bath is removed, and the temperature is increased to room temperature for stirring for 1 hour; the oil bath is heated to 80 o C, and stirred for 6 hours; after the reaction is completed, the reaction is quenched, and the reaction solution is cooled to 0 o C by ice bath; the reaction solution is slowly poured into an ice water mixture, and then a saturated NaOAc solution is added to adjust the pH value to neutral; the organic phase is extracted with ethyl acetate, and washed with deionized water and saturated brine; the organic phase is dried with anhydrous sodium sulfate, and dried and removed by a rotary evaporator; column chromatography is performed on silica gel to purify, and a red solid, i.e. the compound shown in formula III 6, is obtained. The temperature of the reaction in step 6) is 50-100 °C; and the time is 2-20 h; The reaction is performed under a nitrogen atmosphere; The reaction is specifically operated as follows: a round-bottom flask with a magnet is added with a compound represented by formula III6, formula III7, formula III8, air is extracted and nitrogen is filled, the operation is repeated three times, then chloroform is added to the reaction bottle, stirring is performed until complete dissolution, pyridine is punched in, heating is performed to 65 o C, and the reaction is performed overnight; after the reaction is completed, it is cooled to room temperature, quenched with deionized water, and the mixture is extracted with dichloromethane, washed with water twice; the organic layer is dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent, and then the crude product is purified by silica gel column chromatography to obtain a compound represented by formula III9. The temperature of the reaction in step 7) can be 90-120 °C, and specifically can be 110 °C; and the time can be 6-48 h, and specifically can be 12 h; The reaction is performed under a nitrogen atmosphere; The reaction is specifically operated as follows: a round bottom flask with a magnet is added with a compound shown as formula II2, a compound shown as formula III9, tris(dibenzylideneacetone) dipalladium and tri(o-methylphenyl) phosphorus, vacuumed and filled with nitrogen for three times; then anhydrous toluene is added into the reaction flask, 110 o C is heated, and the reaction is carried out for 12 hours; after the reaction is completed, the crude product is purified by silica gel column chromatography to obtain a black solid product, i.e. a compound shown as formula I.

8. The preparation method of claim 7, characterized in that: The molar ratio of the 2,7-dibromofluorene and the 1,3-dibromopropane is 1:1-6, and the molar ratio of the 2,7-dibromofluorene and the potassium hydroxide is 1:4-6; The molar ratio of the compound shown as formula II1 and the n-butyl lithium is 1:2-2.5, and the molar ratio of the compound shown as formula II1 and the trimethyl tin chloride is 1:2-2.5; The molar ratio of the 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and the tributyl(6-undecylthieno[3,2-B]thiophen-2-yl)stannane is 1:2.2-2.5, and the molar ratio of the 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and the bis(triphenylphosphine)palladium dichloride is 1:0.05-0.1; The molar ratio of the compound shown as formula III3 and the compound shown as formula III4 is 1:2.2-2.5; the molar ratio of the compound shown as formula III3 and the triphenylphosphine is 1:0.05-0.1; and the molar ratio of the compound shown as formula III3 and the KOH and the KI is 1:2-3:1-1.5; The molar ratio of the compound shown as formula III5 and the phosphorus oxychloride is 1:1.5-2.5; The molar ratio of the compounds shown as formula III6, formula III7 and formula III8 can be 1:1-1.3:1-1.3; The molar ratio of the compound shown as formula II2 and formula III9 is 1:2; the molar ratio of the compound shown as formula II2, tris(dibenzylideneacetone)dipalladium and tri(o-methylphenyl)phosphine is 1:0.06:2.

4.

9. An active layer of an organic solar cell device, characterized by: The donor material is D18, the acceptor material is L8-BO and the asymmetric Y series acceptor coupled with fluorene as claimed in any one of claims 1-3; the mass ratio is 1:1:0.

1.

10. An organic solar cell device, characterized by: It sequentially comprises ITO substrate, PEDOT:PSS layer, the active layer as claimed in claim 9, PDINN and Ag electrode.

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