An intermediate of a non-fused ring electron acceptor material of A-D-D'-A type and a preparation method thereof

Abstract

The application belongs to the field of organic solar cell materials, and provides an intermediate of a non-fused ring electron acceptor material of A-D-D'-A type, a preparation method and application of the intermediate. The non-fused ring acceptor material of A-D-D'-A type prepared from the intermediate according to the application promotes planarization of a molecular skeleton through non-covalent bond interaction, so that the acceptor molecule has excellent molecular packing orientation, and thus is more conducive to charge transmission. Therefore, the solar cell prepared from the intermediate according to the application has excellent photoelectric properties.

Description

Technical Field

[0001] This invention belongs to the field of organic solar cell materials, and particularly relates to intermediates of fused ring electron acceptor materials, methods for preparing such intermediates, and applications. Background Technology

[0002] Bulk heterojunction (BHJ) organic solar cells (OSCs) have attracted significant interest from academia and industry due to their unique technological advantages, including solution-processability, flexibility, lightweight, and semi-transparency. Thanks to the groundbreaking innovation of the fused-ring electron acceptor structure, the photon-to-electron conversion efficiency (PCE) of single-junction and tandem OSCs has exceeded 17%. To further improve the performance and stability of OSCs to meet the fundamental requirements of commercial applications, researchers have successfully developed device fabrication processes (e.g., using additives, thermal annealing, and solvent vapor annealing) to control the morphology of blended thin films of the active layer.

[0003] On the one hand, in receptor molecule design, extending the conjugation length of the fused-ring core of the receptor is one of the important means to obtain high-performance receptors. However, simply extending the conjugation length of the core can easily lead to drawbacks such as increased synthesis difficulty and excessive molecular aggregation. Therefore, current high-efficiency small molecule receptor materials generally suffer from complex molecular structures, high synthesis costs, and great difficulty.

[0004] On the other hand, from the perspective of device fabrication technology, polymer donor materials and small molecule acceptor materials have different crystallization rates. Adding solvent additives can make the two materials have matching crystallization rates in the blend solution, thereby obtaining a thin film morphology that is conducive to charge transport. However, solvent additives are difficult to remove under the subsequent thermal annealing conditions of the active layer, and during long-term storage of the device, these residual solvent additives will damage the morphology of the active layer, resulting in a significant degradation of device performance. For example, patent application CN113563362A discloses an AD-D'-A type asymmetric organic photovoltaic acceptor material. However, this acceptor material is a fused-ring small molecule, and in the process of mixing it with the acceptor to prepare a solar photovoltaic cell, it is necessary to add solvent additives (such as CN) and perform annealing treatment (such as annealing at 100°C and CS2 solvent vapor annealing treatment successively).

[0005] To obtain stable and efficient organic solar cells, the use of liquid additives with high boiling points should be avoided as much as possible. Although researchers have developed volatile solid additives, such as adding ferrocene or thiophene derivatives to chlorobenzene or chloroform solvents, while these solid additives improve both cell efficiency and stability, they cannot avoid the drawback of these additives being difficult to remove during the annealing process. Summary of the Invention

[0006] This invention provides an intermediate for non-fused-ring electron acceptor materials, aiming to solve the problems of complex structure, high synthesis cost, and great difficulty in synthesizing electron acceptor materials.

[0007] The present invention is implemented as follows: the molecular structural formula of the intermediate is as follows. in:

[0008] R1 is selected from any of the following groups:

[0009]

[0010]

[0011] R2 is -C x H y or -CH(C n H m CxH y x is an integer from 4 to 12, y is an integer from 11 to 23, n is an integer from 2 to 8, and m is an integer from 7 to 15;

[0012] R3 is C 4-10 Alkyl groups;

[0013] R4 is -C a H b -OC a H b , -CH(C c H d C a H b or -OCH(C c H d C a H b a is an integer from 2 to 12, b is an integer from 7 to 23, c is an integer from 1 to 8, and d is an integer from 3 to 15.

[0014] Furthermore, R2 is a saturated alkyl group, and x is an even number from 4 to 12, and n is an even number from 2 to 8.

[0015] Furthermore, R2 is selected from any of the following groups:

[0016] R2=C6H 13 R2=C8H 17 R2 = C 10 H 21

[0017]

[0018] Furthermore, R4 is a saturated alkyl or saturated alkoxy, and a is an even number from 2 to 12, and c is an even number from 2 to 8.

[0019] Furthermore, R4 is selected from any of the following groups:

[0020] R4 = C6H 13 R4 = OC6H 13

[0021] R4 = C8H 17 R4 = OC8H 17

[0022] R4=C 10 H 21 R4 = OC 10 H 21

[0023] The present invention also provides a method for preparing an intermediate according to the present invention, which includes the following steps:

[0024] S1: Compound 1 It undergoes a formylation reaction with N,N-dimethylformamide to generate compound 2.

[0025] S2: Compound 2 It reacts with tributyltin chloride to form compound 3

[0026] S3: Compound 3 With compound 4 The intermediate is generated under the catalysis of a palladium catalyst.

[0027] Furthermore, step S2 is a lithium-halogen exchange reaction and includes the following steps:

[0028] a: N-methylpiperazine reacts with n-butyllithium in tetrahydrofuran to generate Li-methylpiperazine;

[0029] b: After step a is completed, add compound 2, and then add n-butyllithium while stirring;

[0030] c: Add tributyltin chloride at a temperature between -78°C and -20°C;

[0031] d: Pour the mixture obtained in step c into an acidic solution, then neutralize it with an alkaline solution, and finally extract it with an organic solution.

[0032] Furthermore, the reaction in step S1 is carried out in a tetrahydrofuran solvent and in the presence of n-butyllithium.

[0033] Furthermore, the palladium catalyst is tetrakis(triphenylphosphine)palladium or tris(dibenzylideneacetone)dipalladium.

[0034] Furthermore, steps S1, S2, and S3 are performed under nitrogen protection.

[0035] This invention also provides the use of the intermediate according to the invention in the preparation of non-fused-ring electron acceptor materials, said intermediate in combination with compound 6 Under the action of a catalyst, an AD-D'-A type non-fused ring electron acceptor as shown in Formula I is generated. R1 and R4 are defined as above, and X is a halogen.

[0036] Preferably, the catalyst is β-alanine.

[0037] Furthermore, X is either Cl or F.

[0038] The non-fused-ring AD-D'-A type acceptor material prepared from the intermediate according to the present invention promotes the planarization of the molecular backbone through non-covalent interactions, resulting in excellent molecular packing orientation of the acceptor molecules, which is therefore more conducive to charge transport. This endows the solar cells prepared from the intermediate according to the present invention with excellent photoelectric properties. Attached Figure Description

[0039] Figure 1 This is the UV-Vis absorption spectrum of the electron acceptor material DTP-EHT-4F according to Embodiment 1 of the present invention in solution and thin film states;

[0040] Figure 2 This is a schematic diagram of the structure of an organic solar cell prepared from the intermediate according to the present invention;

[0041] Figure 3 The JV curve of the organic solar cell prepared from the non-fused-ring electron acceptor material DTP-EHT-4F of Example 1 is shown.

[0042] Figure 4 The JV curves of organic solar cells with non-fused-ring electron acceptor materials in Comparative Examples 1 to 3 after additive and thermal annealing treatment are shown.

[0043] Figure 5 The JV curves of organic solar cells prepared from non-fused-ring electron acceptor materials in Comparative Examples 4 to 7 after different solvent vapor annealing treatments are shown.

[0044] Figure 6 This is a graph showing the efficiency degradation of an organic solar cell fabricated from the non-fused-ring electron acceptor material DTP-EHT-4F according to Embodiment 1 of the present invention after continuous illumination or heating. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] In acceptor molecule design, extending the conjugation length of the fused-ring core is a crucial method for obtaining high-performance acceptors. However, simply extending the conjugation length can lead to drawbacks such as increased synthetic difficulty and excessive molecular aggregation. This invention employs a non-fused-ring electronic structure, different from traditional fused-ring electron acceptor intermediates, by introducing nitrogen-functionalized two-dimensional side chains into the non-fused-ring electron acceptor structure. The non-fused-ring electron acceptor prepared from the intermediate according to this invention exhibits ideal solubility, achieves ideal phase separation morphology when blended with donor materials, and ensures efficient charge transport without requiring an annealing step during solar cell fabrication.

[0047] In this invention, the term "non-fused-ring electron acceptor" means an electron acceptor comprising at least one monocyclic unit. In this invention, the thiophene unit is a monocyclic unit, while the dithiophene-pyrrole unit is a polycyclic unit, and the thiophene unit and the dithiophene-pyrrole unit are connected only by a single bond to form a conjugated structure.

[0048] Examples of intermediates according to the present invention are as follows:

[0049]

[0050] Example 1

[0051] This embodiment provides a non-fused-ring narrow-bandgap electron acceptor material, DTP-EHT-4F, whose synthesis route is as follows:

[0052]

[0053] The specific synthesis steps are as follows:

[0054] S1: Compound 1 undergoes a Vilsmeier-Haack formylation reaction with N,N-dimethylformamide to generate compound 2.

[0055] Specifically, under nitrogen protection, compound 1 was... (3.0 g, 7.2 mmol) was dissolved in a dry tetrahydrofuran solution (80 mL). Over 10 minutes, n-butyllithium (3.0 mL, 7.2 mmol) was added dropwise to the above solution. After stirring at -78 °C for 1.5 h, N,N-dimethylformamide (DMF) (1.1 g, 14.4 mmol) was added dropwise, and the solution was then warmed to room temperature and stirred for another 1 h. The mixture was poured into ice water (100 mL), neutralized with Na₂CO₃ solution, and extracted with dichloromethane. The organic layer was washed with water and brine and dried over anhydrous MgSO₄. After removing the solvent by rotary evaporation under reduced pressure, the crude product was purified by silica gel column chromatography to give 3.0 g of compound 2. (Yellow solid, yield 93%).

[0056] S2: Compound 2 reacts with tributyltin chloride to form compound 3; more specifically, compound 2 should form compound 3 by undergoing a lithium-halogen exchange reaction with n-butyllithium under low temperature conditions.

[0057] Specifically, under nitrogen protection, N-methylpiperazine (858.6 mL, 7.7 mmol) was dissolved in a dry tetrahydrofuran solution (80 mL). Within 10 minutes, n-butyllithium (3.2 mL, 7.7 mmol) was added dropwise to the solution. After stirring at -78°C for 30 minutes, compound 2 was added... (3 g, 6.7 mmol) was added, and the mixture was stirred again for 30 minutes. Then, n-butyllithium (3.2 mL, 7.7 mmol) was added dropwise to the above solution again. After stirring at -20 °C for 2 h, the temperature was lowered to -78 °C, and tributyltin chloride (2.2 mL, 8.1 mmol) was added dropwise. The solution was then warmed to room temperature and stirred for another 2 h. The mixture was poured into an aqueous hydrochloric acid solution (50 mL), neutralized with Na₂CO₃ solution, and extracted with ethyl acetate. The organic layer was washed with water and brine and dried over anhydrous MgSO₄. After removing the solvent by rotary evaporation under reduced pressure, compound 3 was obtained. (Viscous liquid) was directly incorporated into the synthesis of compound 5 without further purification.

[0058] S3: Compound 3 and compound 4 are coupled together under the catalysis of a palladium catalyst to generate compound 5.

[0059] Specifically, under nitrogen protection, compound 3 was... (1.2g, 1.6mmol), compound 4 (625.7 mg, 2.0 mmol) of dried toluene (12 mL) was placed in a Schlenk vacuum-sealed flask (50 mL). After freezing with liquid nitrogen, the mixture was purged with argon three times, followed by the addition of tetraphenylphosphine palladium (37.8 mg, 32.7 μmol). The mixture was heated to reflux at 110 °C for 6 hours. After the reaction was completed and cooled to room temperature, the reaction solution was filtered through diatomaceous earth, the organic phase was collected, washed with water, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give 940 mg of compound 5. (Orange viscous liquid, yield 82%), which is the intermediate according to the present invention.

[0060] S4: Compound 5 and compound 6 (fluoroindanedione) react with a catalyst via Knoevenagel to generate compound 7DTP-EHT-4F.

[0061] Specifically, compound 5 Fluorinated indanedione (200 mg, 292 μmol) was dissolved in a mixture of 1,2-dichloroethane (20 mL) and dry ethanol (4 mL), and β-alanine (2.6 mg, 29.2 μmol) was added. The mixture was heated under reflux at 55 °C for 12 hours. After the reaction was complete, the reaction solution was extracted with dichloromethane, the organic phase was collected, washed with water, and the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography to give 240 mg of the final product DTP-EHT-4F (dark black solid, yield 75%).

[0062] When R1 is And R2 is a straight-chain alkyl-C x H y or branched alkyl-CH(C) n H m C x H y This effectively ensures the solubility of the acceptor molecules, allowing for a more ideal phase separation morphology when the acceptor molecules are blended with the polymer donor material. Specifically, an ideal phase separation morphology refers to an interpenetrating nanofiber network structure. Under this ideal film morphology, excitons are effectively separated, charge can be transported efficiently, the fill factor (FF) is significantly improved, and the PCE (photoelectric conversion efficiency) is naturally enhanced.

[0063] When R1 is a cyclic group, it can exert a steric hindrance effect, inhibiting excessive self-aggregation of acceptor molecules. However, steric hindrance and solubility need to be balanced. In this invention, the C5-C10 straight-chain alkyl group R3 can balance steric hindrance and solubility.

[0064] Furthermore, by introducing nitrogen-functionalized two-dimensional side chains into the design of non-fused-ring electron acceptors based on the dithiophene-pyrrole (DTP) unit of compound 1, excessive self-aggregation of acceptor molecules can be effectively suppressed. Unlike carbon-functionalized two-dimensional side chains, the electron-rich nitrogen atoms in DTP can improve the stability of organic semiconductors in the oxidized state, thereby increasing the operating time of optoelectronic devices. Simultaneously, due to the steric hindrance between the two-dimensional side chains and adjacent thiophene groups, a certain dihedral angle is generated between the two-dimensional side chains and the core framework, which can effectively improve the stacking orientation of acceptor molecules, providing more charge transport channels for both lateral and longitudinal transport. Therefore, the battery prepared using the acceptor of this invention exhibits superior photoelectric performance.

[0065] The synthesis of the non-fused-ring electron acceptor intermediate according to the present invention is simple, requiring only three synthetic steps to obtain the intermediate. Furthermore, the synthesis steps from the intermediate to the final non-fused-ring electron acceptor are also simple, the separation and purification are straightforward, and the yield is ideal.

[0066] like Figure 1 As shown, the maximum absorption peak of the non-fused-ring narrow-bandgap electron acceptor material DTP-EHT-4F is located at 713 nm in solution and at 802 nm in thin film. From solution to thin film, the DTP-EHT-4F acceptor molecule exhibits a nearly 90 nm redshift. Furthermore, the onset absorption edge of the DTP-EHT-4F acceptor molecule in thin film can be observed at 905 nm, corresponding to an optical bandgap of 1.37 eV.

[0067] Example 2

[0068] In Example 2, the specific structure of compound 1 is as follows: Furthermore, the electron acceptor structure DTP-Th-EHT-4F was finally synthesized as follows:

[0069]

[0070] Example 3

[0071] In Example 3, the specific structure of compound 1 is as follows: Furthermore, the electron acceptor structure DTP-Ph-EHT-4F was finally synthesized as follows:

[0072]

[0073] Example 4

[0074] In Example 4, the specific structure of compound 1 is as follows: Furthermore, the electron acceptor structure DTP-TT-EHT-4F was finally synthesized as follows:

[0075]

[0076] The specific synthesis method of compound 1 in Examples 2 to 4 has been reported in the inventor's published literature "2DSide-ChainEngineered Asymmetric Acceptors Enabling Over 14% Efficiency and 75% FillFactor Stable Organic Solar Cells" (Jinru Cao etc.Adv.Funct.Mater.2020,2006141).

[0077] Example 5

[0078] This embodiment provides an organic solar cell fabricated from a non-fused-ring electron acceptor material. For example... Figure 2 As shown, the glass substrate comprises, from bottom to top: a cathode electrode, an electron transport layer, an active layer, a hole transport layer, and an anode electrode.

[0079] The specific fabrication steps for organic solar cells are as follows:

[0080] Step 1: The transparent conductive glass with striped ITO (cathode) etched on its surface is cleaned sequentially using glass cleaner, deionized water, acetone, and isopropanol as cleaning agents under ultrasonic conditions. The ultrasonic time for each step is 15 minutes. The cleaned ITO glass is dried with a nitrogen gun and then placed in a vacuum plasma machine for 3 minutes to optimize the surface wettability and work function of the ITO.

[0081] Step 2: The preparation method of the electron transport layer ZnO is as follows: 1g of zinc acetate dihydrate particles and 0.28g of ethanolamine were dissolved in 10mL of 2-methoxyethanol solution and stirred at room temperature for 5h. Then, the mixed solution was uniformly spin-coated onto the surface of ITO glass at 5000 rpm for 30s. The spin-coated ZnO substrate was then placed on a heating stage at 200℃ and annealed for 1h.

[0082] Step 3: The preparation of the active layer was completed in a nitrogen-filled glove box. The active layer solution was prepared by dissolving the donor material PM6 and the acceptor material in chloroform solvent, with a total concentration of 15 mg / mL and a donor-to-acceptor mass ratio of 1:1. The mixture was stirred at room temperature for 12 hours to ensure complete dissolution. The mixture was then spin-coated onto a ZnO film at 3000 rpm for 30 seconds. Compared with existing device fabrication techniques, the device prepared from the intermediate according to this invention does not require annealing or the addition of high-boiling-point additives during the fabrication process, yet still achieves good photoelectric conversion efficiency, which will be described in detail below.

[0083] Step 4: Both the hole transport layer MoO3 and the metal electrode Ag were prepared by vacuum evaporation, and the preparation process is as follows: at 5×10 -4 At low pressures below Pa, respectively, 0.1 / s and 1 The films were deposited at a rate of / s, with thicknesses of 10nm and 150nm, respectively. The effective area of ​​the cell is 3.97mm². 2 .

[0084] Comparative Example

[0085] In Comparative Examples 1 to 7, only the preparation process in step 3 is different, while the remaining steps 1, 2 and 4 remain unchanged.

[0086] The preparation process of the active layer in Comparative Example 1 is as follows: The donor material PM6 and the acceptor material DTP-EHT-4F were dissolved in chloroform solvent, with a total concentration of 15 mg / mL and a donor-to-acceptor mass ratio of 1:1. The mixture was stirred at room temperature for 12 h to ensure complete dissolution. Then, the mixture was spin-coated onto a ZnO film at 3000 rpm for 30 s. Finally, the active layer was annealed at 100 °C for 10 min.

[0087] The preparation process of the active layer in Comparative Example 2 is as follows: The donor material PM6 and the acceptor material DTP-EHT-4F were dissolved in chloroform solvent, with a total concentration of 15 mg / mL and a donor-to-acceptor mass ratio of 1:1. 0.5% DIO (by volume) was added as an additive. The mixture was stirred at room temperature for 12 h to ensure complete dissolution. Then, the mixture was spin-coated onto a ZnO film at 3000 rpm for 30 s.

[0088] The preparation process of the active layer in Comparative Example 3 is as follows: The donor material PM6 and the acceptor material DTP-EHT-4F were dissolved in chloroform solvent, with a total concentration of 15 mg / mL and a donor-to-acceptor mass ratio of 1:1. 0.5% DIO (by volume) was added as an additive. The mixture was stirred at room temperature for 12 h to ensure complete dissolution. Then, the mixture was spin-coated onto a ZnO film at 3000 rpm for 30 s. Finally, the active layer was annealed at 100 °C for 10 min.

[0089] The preparation process of the active layer in Comparative Example 4 is as follows: The donor material PM6 and the acceptor material DTP-EHT-4F were dissolved in chloroform solvent, with a total concentration of 15 mg / mL and a donor-to-acceptor mass ratio of 1:1. The mixture was stirred at room temperature for 12 h to ensure complete dissolution. Then, the mixture was spin-coated onto a ZnO film at 3000 rpm for 30 s. Finally, the active layer was placed in a 1.5 cm diameter petri dish, and 45 μL of chloroform solvent was quickly added along the edge of the dish. The dish was then capped and annealed with solvent vapor for 15 s.

[0090] Similar to Comparative Example 4, the only difference in Comparative Example 5 is that the solution in the solution vapor annealing step is 45 μL of dichloromethane solvent; the only difference in Comparative Example 6 is that the solution in the solution vapor annealing step is 45 μL of carbon disulfide solvent; and the only difference in Comparative Example 7 is that the solution in the solution vapor annealing step is 45 μL of tetrahydrofuran solvent.

[0091] Using AM1.5G spectral distribution and illuminance of 100 mw / cm², 2 Using an Oriel 300W solar simulator as the light source, the photoelectric performance of the organic solar cells prepared from the intermediates according to the present invention and the organic solar cells obtained in Comparative Examples 1 to 7 was tested. The JV curves were obtained by measuring with a Keithly 2400 digital source meter. Figure 4 and Figure 5 As shown in the figure, the photoelectric performance test parameters are obtained, as shown in Table 1.

[0092] Table 1: Comparison of photoelectric performance test parameters of solar cells in Examples 1-4 and Comparative Examples 1-7

[0093]

[0094]

[0095] As shown in Table 1, compared to the various device optimization strategies used in the comparative examples, including organic solar cells prepared by adding additives, thermal annealing, and solvent vapor annealing, the devices prepared using the intermediates according to the present invention still achieved a photoelectric conversion efficiency of 7.6-8.6% without any additives or annealing treatment. This superior photoelectric performance demonstrates that the non-fused-ring AD-D'-A type acceptor material prepared using the intermediates according to the present invention can promote the planarization of the molecular framework through non-covalent interactions, greatly reducing the complexity and cost of acceptor material synthesis, and also endowing structurally simple acceptor materials with excellent photoelectric properties.

[0096] To further observe the stability of devices directly fabricated based on this acceptor material (as-cast) under conditions without any additives or annealing, we placed devices fabricated from DTP-EHT-4F in a glove box and tested their efficiency after 200 hours of continuous illumination or 200 hours of continuous heating (at 85°C). Figure 6 As shown, after continuous illumination or heating in a glove box for 200 hours, the directly prepared device still maintains more than 90% of its initial efficiency, further demonstrating that this acceptor material has excellent photovoltaic performance and is expected to be used in semi-transparent and indoor photovoltaic devices.

[0097] In summary, the non-fused-ring AD-D'-A type acceptor material prepared according to the intermediates of the present invention has a non-fused-ring framework, which greatly reduces the complexity and cost of acceptor material synthesis. Furthermore, the acceptor material prepared according to the intermediates of the present invention promotes planarization of the molecular framework through non-covalent interactions, resulting in excellent molecular packing orientation of the acceptor molecules, thus facilitating charge transport. This endows the solar cells prepared from the intermediates of the present invention with excellent photoelectric properties.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An intermediate of a non-fused ring electron acceptor material of A-D-D'-A type, characterized by, The A-D-D'-A non-fused electron acceptor material is applied to prepare an active layer of an organic solar cell, the intermediate has a general structural formula as shown in formula II wherein: R1 is selected from any one of the following groups: ， R3is C 4-10 alkyl; R4is -C a H b , -OC a H b , -CH(C c H d )C a H b or -OCH(C c H d )C a H b , a is an integer from 2 to 12, b is an integer from 7 to 23, c is an integer from 1 to 8, d is an integer from 3 to 15.

2. The intermediate of claim 1, wherein, R4 is a saturated alkyl or saturated alkoxy, and a is an even number from 2 to 12, and c is an even number from 2 to 8.

3. The intermediate of claim 1 or 2, wherein, R4 is selected from any one of the following groups: 。 4. The method of producing an intermediate according to any one of claims 1 to 3, wherein The method comprises the following steps: S1 : Compound 1 formylation reaction with N,N-dimethylformamide to give Compound 2 ; S2: said compound 2 with tributyltin chloride to give compound 3 ; S3: the compound 3 with compound 4 under catalysis of a palladium catalyst to form an intermediate as shown in formula II .

5. The production method according to claim 4, wherein Step S2 is a lithium-halogen exchange reaction, and The method comprises the following steps: a: N-methylpiperazine reacts with n-butyllithium in tetrahydrofuran to generate Li-methylpiperazine; b: after step a is completed, compound 2 is added, then n-butyllithium is added under stirring; c: tributyltin chloride is added at a temperature between -78°C and -20°C; d: the mixture obtained in step c is poured into an acidic solution, then neutralized with a basic solution, and finally extracted with an organic solution.

6. The production method according to claim 4, wherein The reaction in step S1 is carried out in a tetrahydrofuran solvent and in the presence of n-butyllithium.

7. The production method according to claim 4, wherein The palladium catalyst is tetrakis triphenylphosphine palladium or tris (dibenzylideneacetone) dipalladium.

8. The production method according to claim 4, wherein Steps S1, S2 and S3 are carried out under nitrogen protection.

9. Use of the intermediate according to any one of claims 1 to 3 for the preparation of a non-fused electron acceptor material, characterized in that, said intermediate with compound 6 under the action of a catalyst to form a non-fused ring electron acceptor of the type A-D-D'-A as shown in formula I wherein R1, R4 are as defined in any one of claims 1 to 3, and X is halogen.

10. Use according to claim 9, wherein the compound is ###0002### The catalyst is beta-alanine.

11. Use according to claim 9, wherein the compound is ###00006### 10 X is Cl or F.

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