An n-type polymer semiconductor material and a preparation method and application thereof

Abstract

This invention discloses an N-type polymer semiconductor material, its preparation method, and its applications. The preparation method includes: step one, preparation of the intermediate BDTT-Br; step two, preparation of the brominated monomer BDTOT-Br; and step three, preparation of the target polymer PBDTOT-BTZ. This invention introduces benzodithiophene tetraoxide structural units into a polymer conjugated system and copolymerizes them with benzothiadiazole structures to prepare an N-type polymer semiconductor material based on benzodithiophene. This material has the advantages of simple molecular structure and short synthesis steps. Field-effect transistors fabricated from this N-type polymer semiconductor material as the active layer exhibit high electron mobility, outperforming existing polymer semiconductor materials based on the benzodithiophene structure. It can be widely used in high-end electronic device fields such as organic integrated circuits, organic chips, wearable electronic devices, and flexible sensors, and has broad application prospects and significant industrialization value.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to an N-type polymer semiconductor material, its preparation method, and its applications. Background Technology

[0002] Compared with traditional inorganic semiconductor materials, organic polymer semiconductor materials have significant advantages such as good flexibility, light weight, easy processing, low cost, and large-area preparation by solution method. Polymer field-effect transistors with this as the active layer have shown great application potential in organic integrated circuits, flexible displays, sensors and other fields. According to the charge carrier type, polymer semiconductors can be divided into two types: P-type and N-type. However, the research progress of N-type polymers is significantly lagging behind that of P-type polymers.

[0003] Benzo[1,2-b:4,5-b']dithiophene, due to its high planarity, high carrier transport properties, and easily modifiable structure, has become an important basic unit of organic electronic materials and is widely used in the field of organic photovoltaics. However, its application in organic transistors is extremely limited, and its carrier mobility is generally below 0.01 cm²・V⁻¹・s⁻¹. More importantly, all reported benzothiophene polymers are p-type semiconductors, and no n-type polymer semiconductor materials based on benzodithiophene have been reported. Therefore, this paper proposes an n-type polymer semiconductor material, its preparation method, and its applications. Summary of the Invention

[0004] The purpose of this invention is to provide an N-type polymer semiconductor material, its preparation method, and its application, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an N-type polymer semiconductor material, wherein the structure of the N-type polymer is as follows:

[0006] Where: R1 is hydrogen, C1~C 60 Straight-chain or branched alkyl groups, C7-C6 60 R2 is any one of the aryl alkyl groups; R2 is hydrogen, C1 to C2. 60 Straight-chain or branched alkyl groups, C1-C 60 Straight-chain or branched alkoxy groups, C1-C 60 Straight-chain or branched alkylthio groups, C7-C6 60 It can be any one of the aralkyl groups, X can be any one of the halogens F, Cl, Br and I, and n is the degree of polymerization of the polymer, which can be any integer from 10 to 100.

[0007] R1 is preferably CH3, and R2 is preferably a straight-chain alkyl group C. 12 H 25X is preferably F.

[0008] A method for preparing an N-type polymer semiconductor material includes step one, preparation of intermediate BDTT-Br; step two, preparation of brominated monomer BDTOT-Br; and step three, preparation of target polymer PBDTOT-BTZ. In step one above, under the protection of an inert gas, compound BDTT is dissolved in an anhydrous organic solvent, cooled to the reaction temperature and reacted with n-butyllithium. After the reaction is completed, carbon tetrabromide is added to continue the reaction, and the intermediate BDTT-Br is obtained after post-treatment. In step two above, the intermediate BDTT-Br is dissolved in an organic solvent and reacted with m-chloroperoxybenzoic acid to undergo an oxidation reaction, and then post-processed to obtain the brominated monomer BDTOT-Br. In step three above, under inert gas protection, using an organic solvent and carbonate aqueous solution as a mixed solvent, a palladium catalyst and a phosphine ligand are added to conduct a Suzuki coupling copolymerization reaction between the brominated monomer BDTOT-Br and the borate ester monomer BTZ-Bpin. After post-treatment, the target polymer PBDTOT-BTZ is obtained.

[0009] In step one, the inert gas is either nitrogen or argon; the anhydrous organic solvent is either tetrahydrofuran, 1,4-dioxane, or ethylene glycol dimethyl ether, preferably tetrahydrofuran; the molar ratio of BDTT, n-butyllithium, and carbon tetrabromide is 1:2.1–2.8:2.5–3.5, preferably 1:2.6:3.0; the reaction temperature of BDTT and n-butyllithium is -78°C, and the reaction time is 0.5–2 hours, preferably 1 hour; after adding carbon tetrabromide, the reaction continues for 5–20 hours, preferably 12 hours.

[0010] In step one, the post-treatment is as follows: after the reaction is complete, deionized water is added, and the mixture is extracted 2-3 times with dichloromethane. All organic phases are combined, anhydrous magnesium sulfate is added to the organic phase, the drying agent is removed by filtration, the filtrate is transferred to a rotary evaporator, and dichloromethane and tetrahydrofuran are removed by rotary evaporation under reduced pressure to obtain a yellow oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain a pale yellow solid intermediate BDTT-Br.

[0011] In step two, the organic solvent is one of dichloromethane, trichloromethane, and toluene, preferably dichloromethane; the molar ratio of intermediate BDTT-Br to m-chloroperoxybenzoic acid is 1:2.5 to 3.5, preferably 1:3; the reaction temperature is room temperature, and the reaction time is 8 to 15 hours, preferably 12 hours.

[0012] In step two, the post-treatment is as follows: after the reaction is complete, saturated sodium carbonate solution is added, and the mixture is extracted 2-3 times with dichloromethane. All organic phases are combined, and anhydrous magnesium sulfate is added to the organic phase for drying. The desiccant is removed by filtration, and the filtrate is transferred to a rotary evaporator. Dichloromethane is removed by rotary evaporation under reduced pressure to obtain an orange-red oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain an orange solid brominated monomer BDTOT-Br.

[0013] In step three, the inert gas is either nitrogen or argon; the organic solvent is either toluene, ethylbenzene, xylene, chlorobenzene, or dichlorobenzene; the carbonate aqueous solution is either a 2 mol / L potassium carbonate aqueous solution or a sodium carbonate aqueous solution; the palladium catalyst is either tetraphenylphosphine palladium or tridibenzylacetone dipalladium; the phosphine ligand is either triphenylphosphine, tri-o-tolylphosphine, tri-2-furanylphosphine, or 2-di-tert-butylphosphine biphenyl; the amount of palladium catalyst is 0.1-10% of the molar amount of the brominated monomer BDTOT-Br, preferably 2.6%; the molar ratio of palladium catalyst to phosphine ligand is 1:3-8, preferably 1:4; the temperature of the Suzuki coupling copolymerization reaction is 80-120°C, preferably 120°C, and the reaction time is 8-48 hours, preferably 24 hours.

[0014] In step three, the post-processing is as follows: After the reaction is completed, the mixture is cooled to room temperature, and the reaction system is poured into methanol to precipitate the solid. The polymer precipitates as a brownish-black solid. The solid polymer is collected by filtration, and the solid polymer is extracted sequentially with methanol, acetone, and n-hexane to remove unreacted monomers, catalyst residues, and low molecular weight oligomers. Finally, the target product is extracted with chloroform, and the chloroform solution of the target product is concentrated by rotary evaporation. The concentrate is poured into methanol, and the polymer solid precipitates again. The solid is collected by suction filtration and dried to obtain the brownish-black solid target polymer PBDTOT-BTZ.

[0015] The above-mentioned N-type polymer semiconductor material is used in the fabrication of organic electronic devices, specifically organic field-effect transistors (OFETs). The N-type polymer semiconductor material is used as the active layer of the OFET, and the performance parameters of the OFET tested in air are: electron mobility of 0.05–0.27 cm⁻¹. 2 V -1 s -1 The threshold voltage is -22 to 13V; the current switching ratio is 10. 5 ~10 6 .

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention introduces benzodithiophene tetroxide structural units into a polymer conjugated system and copolymerizes them with benzothiadiazole structures to prepare an N-type polymer semiconductor material based on benzodithiophene. It has the advantages of simple molecular structure and short synthesis steps. The field-effect transistors prepared by the active layer of this N-type polymer semiconductor material exhibit high electron mobility and outperform existing polymer semiconductor materials based on the benzodithiophene structure. It can be widely used in high-end electronic device fields such as organic integrated circuits, organic chips, wearable electronic devices, and flexible sensors, and has broad application prospects and important industrialization value. Attached Figure Description

[0017] Figure 1 This is a flowchart of the steps of the present invention; Figure 2 This is a flowchart of the method of the present invention; Figure 3 Here is the flowchart of the method in Experiment Example 1; Figure 4 The transfer curves of the field-effect transistor based on PBDTOT-BTZ-1 are shown. Figure 5 The output curve of the field-effect transistor based on PBDTOT-BTZ-1 is shown. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see the appendix Figure 1 - Appendix Figure 2 The present invention provides a technical solution: an N-type polymer semiconductor material, the structure of which is as follows:

[0020] Where: R1 is hydrogen, C1~C 60 Straight-chain or branched alkyl groups, C7-C6 60 R2 is any one of the aryl alkyl groups; R2 is hydrogen, C1 to C2. 60 Straight-chain or branched alkyl groups, C1-C 60 Straight-chain or branched alkoxy groups, C1-C 60 Straight-chain or branched alkylthio groups, C7-C6 60R1 is any one of the aryl alkyl groups, X is any one of the halogens F, Cl, Br and I, and n is the degree of polymerization of the polymer, taking any integer value from 10 to 100; R1 is preferably CH3, and R2 is preferably a straight-chain alkyl group C. 12 H 25 X is preferably F.

[0021] A method for preparing an N-type polymer semiconductor material includes step one, preparation of intermediate BDTT-Br; step two, preparation of brominated monomer BDTOT-Br; and step three, preparation of target polymer PBDTOT-BTZ. In step one above, under an inert gas atmosphere, compound BDTT is dissolved in an anhydrous organic solvent, cooled to the reaction temperature, and then reacted with n-butyllithium. After the reaction is complete, carbon tetrabromide is added to continue the reaction, and the intermediate BDTT-Br is obtained after post-treatment. The inert gas is either nitrogen or argon; the anhydrous organic solvent is either tetrahydrofuran, 1,4-dioxane, or ethylene glycol dimethyl ether, preferably tetrahydrofuran; the molar ratio of BDTT, n-butyllithium, and carbon tetrabromide is 1:2.1–2.8:2.5–3.5, preferably 1:2.6:3.0; the reaction of BDTT with n-butyllithium... The temperature is -78℃, and the reaction time is 0.5 to 2 hours, preferably 1 hour. After adding carbon tetrabromide, the reaction continues for 5 to 20 hours, preferably 12 hours. The post-treatment is as follows: after the reaction is completed, deionized water is added, and the mixture is extracted with dichloromethane 2 to 3 times. All organic phases are combined, and anhydrous magnesium sulfate is added to the organic phase. The drying agent is removed by vacuum filtration, and the filtrate is transferred to a rotary evaporator. Dichloromethane and tetrahydrofuran are removed by rotary evaporation under reduced pressure to obtain a yellow oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain a pale yellow solid intermediate BDTT-Br. In step two above, the intermediate BDTT-Br is dissolved in an organic solvent and reacted with m-chloroperoxybenzoic acid to undergo an oxidation reaction. After post-treatment, the brominated monomer BDTOT-Br is obtained. The organic solvent is one of dichloromethane, trichloromethane, and toluene, preferably dichloromethane. The molar ratio of intermediate BDTT-Br to m-chloroperoxybenzoic acid is 1:2.5-3.5, preferably 1:3. The reaction temperature is room temperature, and the reaction time is 8-15 hours, preferably 12 hours. The post-treatment is as follows: after the reaction, saturated sodium carbonate solution is added, and the mixture is extracted 2-3 times with dichloromethane. All organic phases are combined, and anhydrous magnesium sulfate is added to the organic phase for drying. The drying agent is removed by vacuum filtration, and the filtrate is transferred to a rotary evaporator. Dichloromethane is removed by rotary evaporation under reduced pressure to obtain an orange-red oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain an orange solid brominated monomer BDTOT-Br. In step three above, under inert gas protection, using an organic solvent and a carbonate aqueous solution as a mixed solvent, a palladium catalyst and a phosphine ligand are added to induce a Suzuki coupling copolymerization reaction between the brominated monomer BDTOT-Br and the borate ester monomer BTZ-Bpin. After post-treatment, the target polymer PBDTOT-BTZ is obtained. The inert gas is either nitrogen or argon; the organic solvent is either toluene, ethylbenzene, xylene, chlorobenzene, or dichlorobenzene; the carbonate aqueous solution is either a 2 mol / L potassium carbonate aqueous solution or a sodium carbonate aqueous solution; the palladium catalyst is either tetratetraphenylphosphine palladium or tridibenzylacetone dipalladium; the phosphine ligand is either triphenylphosphine, tri-o-tolylphosphine, tri-2-furanylphosphine, or 2-di-tert-butylphosphine biphenyl; and the amount of palladium catalyst used is 0.1 molar of the brominated monomer BDTOT-Br. ~10%, preferably 2.6%; the molar ratio of palladium catalyst to phosphine ligand is 1:3 to 8, preferably 1:4; the temperature of Suzuki coupling copolymerization reaction is 80 to 120°C, preferably 120°C, and the reaction time is 8 to 48 hours, preferably 24 hours; the post-treatment is as follows: after the reaction is completed, cool to room temperature, pour the reaction system into methanol to precipitate the solid, the polymer precipitates as a brownish-black solid, filter and collect the solid polymer, and extract the solid polymer sequentially with methanol, acetone and n-hexane to remove unreacted monomers, catalyst residues and low molecular weight oligomers, and finally extract the target product with chloroform, concentrate the chloroform solution of the target product by rotary evaporation, pour the concentrate into methanol, precipitate the polymer solid again, filter and collect the solid, and dry to obtain the brownish-black solid target polymer PBDTOT-BTZ.

[0022] Experimental Example 1: The polymer PBDTOT-BTZ-1 was prepared using the method proposed in the above embodiments. The method flow is attached. Figure 3 As shown, the process includes step one, preparation of intermediate BDTT-Br-1; step two, preparation of brominated monomer BDTOT-Br-1; and step three, preparation of target polymer PBDTOT-BTZ-1. In step one above, under an inert gas atmosphere, compound BDTT (500 mg, 0.67 mmol) was dissolved in 10 mL of anhydrous tetrahydrofuran and cooled to -78°C. o After step C, a hexane solution of n-butyllithium (1.6 mol / L, 1.1 mL) was added to initiate the reaction, and the mixture was kept at -78°C. oAfter stirring for 1 hour, a tetrahydrofuran solution (10 mL) of carbon tetrabromide (662 mg, 2.00 mmol) was added. The mixture was stirred at room temperature for 12 hours. After the reaction was complete, 25 mL of water was added, and the mixture was extracted with dichloromethane (2 × 25 mL). The extract was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed. The crude product was purified by column chromatography to obtain a pale yellow solid, namely intermediate BDTT-Br-1 (499 mg, 82%). The NMR data of BDTT-Br-1 are as follows: 1 HNMR (400MHz, CDCl3) δ (ppm): 7.41 (s, 2H), 6.95 (s, 2H), 4.14 (s, 6H), 2.82 (t, 4H), 1.66 (m, 4H), 1.26–1.43 (m, 36H), 0.87 (t, 6H); In step two above, the intermediate BDTT-Br-1 (450 mg, 0.495 mmol) was dissolved in dichloromethane (10 mL), and then m-chloroperoxybenzoic acid (256 mg, 1.49 mmol) was added to the solution. After stirring the mixture at room temperature for 12 hours, a saturated sodium carbonate solution was added, and the mixture was extracted with dichloromethane (2 × 25 mL). The extract was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed. The crude product was purified by column chromatography to obtain an orange solid, namely BDTOT-Br-1 (322.7 mg, 67%). The NMR data of BDTOT-Br-1 are as follows: 1 HNMR (400MHz, CDCl3) δ (ppm): 7.20 (s, 2H), 7.04 (s, 2H), 4.32 (s, 6H), 2.71 (t, 4H), 1.64 (m, 4H), 1.25–1.43 (m, 36H), 0.88 (t, 6H); In step three above, BDTOT-Br-1 (243 mg, 0.25 mmol) and compound BTZ-Bpin-1 (106 mg, 0.25 mmol) were dissolved in 5.0 mL of toluene and 1.0 mL of 2 mol / L potassium carbonate aqueous solution. The mixture was bubbled with nitrogen for 10 minutes. Then, the catalyst tris(dibenzylacetone)palladium (5.95 mg, 0.0065 mmol) and the ligand tri-o-tolylphosphine (7.91 mg, 0.026 mmol) were added. The reaction tube was then purged to replace the nitrogen atmosphere, and the reaction was carried out at 120 °C. The reaction was terminated after 24 hours. After cooling the reaction system to room temperature, the solid was precipitated in 100 mL of methanol and filtered. The obtained polymer solid was then subjected to Soxhlet extraction with methanol, acetone, and n-hexane to remove impurities and low molecular weight fractions. Finally, the target product was extracted with chloroform. The chloroform solution of the target product was concentrated by rotary evaporation and then precipitated in 100 mL of methanol to obtain the polymer solid. The solid was then filtered and dried to obtain polymer PBDTOT-BTZ-1 (176.51 mg, yield: 71.8%). Elemental analysis of polymer PBDTOT-BTZ-1: Calculated value C. 50 H 60 F2N2O6S5 (%): C, 61.07; H, 6.15; N, 1.40; Measured values: C, 61.49; H, 6.02; N, 1.38; The number-average molecular weight M was determined by gel permeation chromatography. n =18.8kDa, polydispersity index (PDI) =1.6.

[0023] Experimental Example 2: The polymer PBDTOT-BTZ-1 prepared in Example 1 was prepared into a 5 mg / mL chlorobenzene solution for later use. 40 μL of this solution was pipetted onto a 1 × 1 cm benzocyclobutene (BCB) modified Si / SiO2 wafer at 1000 rpm to form a film. After annealing at 120 °C for 10 minutes, it was used as the active layer of a field-effect transistor. A 40 nm gold electrode was deposited onto the surface of the active layer using vacuum evaporation to form the top contact electrode. The channel length and width were 200 and 1000 μm, respectively. The performance of the field-effect transistor was tested, and the results are shown in the appendix. Figure 4 - Appendix Figure 5 As shown, the fabricated field-effect transistor is an N-type organic semiconductor. The performance parameters of the organic field-effect transistor tested in air are: electron mobility 0.05–0.27 cm⁻¹ 2 V - 1 s -1 The threshold voltage is -22 to 13V; the current switching ratio is 10. 5 ~10 6Device testing results demonstrate the application value of polymer PBDTOT-BTZ-1 in various high-end electronic device fields such as organic integrated circuits, flexible sensors, and organic chips.

[0024] Based on the above, this invention employs a reasonable molecular design strategy to introduce benzodithiophene tetroxide structural units into a polymer conjugated system for the first time, and copolymerizes them with benzothiadiazole structures to prepare N-type polymer semiconductor materials based on benzodithiophene, filling a technological gap in this field. The polymer has a simple molecular structure, the synthesis route involves only three core reactions, the reaction conditions are mild, the post-processing is conventional, the raw materials are readily available, and it has good scalability. Furthermore, the device fabrication process is mature and easy to operate, and the electron mobility of the obtained N-type polymer semiconductor material is significantly better than that of existing polymer semiconductor materials based on the benzodithiophene structure.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An N-type polymer semiconductor material, characterized in that: The structure of the N-type polymer is as follows: Where: R1 is hydrogen, C1~C 60 Straight-chain or branched alkyl groups, C7-C6 60 R2 is any one of the aryl alkyl groups; R2 is hydrogen, C1 to C2. 60 Straight-chain or branched alkyl groups, C1-C 60 Straight-chain or branched alkoxy groups, C1-C 60 Straight-chain or branched alkylthio groups, C7-C6 60 It can be any one of the aralkyl groups, X can be any one of the halogens F, Cl, Br and I, and n is the degree of polymerization of the polymer, which can be any integer from 10 to 100.

2. An N-type polymer semiconductor material according to claim 1, characterized in that: R1 is preferably CH3, and R2 is preferably a straight-chain alkyl group C. 12 H 25 X is preferably F.

3. A method for preparing an N-type polymer semiconductor material, comprising: step one, preparation of intermediate BDTT-Br; step two, preparation of brominated monomer BDTOT-Br; and step three, preparation of target polymer PBDTOT-BTZ; characterized in that: In step one above, under the protection of an inert gas, compound BDTT is dissolved in an anhydrous organic solvent, cooled to the reaction temperature and reacted with n-butyllithium. After the reaction is completed, carbon tetrabromide is added to continue the reaction, and the intermediate BDTT-Br is obtained after post-treatment. In step two above, the intermediate BDTT-Br is dissolved in an organic solvent and reacted with m-chloroperoxybenzoic acid to undergo an oxidation reaction, and then post-processed to obtain the brominated monomer BDTOT-Br. In step three above, under inert gas protection, using an organic solvent and carbonate aqueous solution as a mixed solvent, a palladium catalyst and a phosphine ligand are added to conduct a Suzuki coupling copolymerization reaction between the brominated monomer BDTOT-Br and the borate ester monomer BTZ-Bpin. After post-treatment, the target polymer PBDTOT-BTZ is obtained.

4. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step one, the inert gas is either nitrogen or argon; the anhydrous organic solvent is either tetrahydrofuran, 1,4-dioxane, or ethylene glycol dimethyl ether, preferably tetrahydrofuran; the molar ratio of BDTT, n-butyllithium, and carbon tetrabromide is 1:2.1–2.8:2.5–3.5, preferably 1:2.6:3.0; the reaction temperature of BDTT and n-butyllithium is -78°C, and the reaction time is 0.5–2 hours, preferably 1 hour; after adding carbon tetrabromide, the reaction continues for 5–20 hours, preferably 12 hours.

5. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step one, the post-treatment is as follows: after the reaction is complete, deionized water is added, and the mixture is extracted 2-3 times with dichloromethane. All organic phases are combined, anhydrous magnesium sulfate is added to the organic phase, the drying agent is removed by filtration, the filtrate is transferred to a rotary evaporator, and dichloromethane and tetrahydrofuran are removed by rotary evaporation under reduced pressure to obtain a yellow oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain a pale yellow solid intermediate BDTT-Br.

6. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step two, the organic solvent is one of dichloromethane, trichloromethane, and toluene, preferably dichloromethane; the molar ratio of intermediate BDTT-Br to m-chloroperoxybenzoic acid is 1:2.5 to 3.5, preferably 1:3; the reaction temperature is room temperature, and the reaction time is 8 to 15 hours, preferably 12 hours.

7. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step two, the post-treatment is as follows: after the reaction is complete, saturated sodium carbonate solution is added, and the mixture is extracted 2-3 times with dichloromethane. All organic phases are combined, and anhydrous magnesium sulfate is added to the organic phase for drying. The desiccant is removed by filtration, and the filtrate is transferred to a rotary evaporator. Dichloromethane is removed by rotary evaporation under reduced pressure to obtain an orange-red oily crude product. The crude product is purified by silica gel column chromatography, the target component is collected, the solvent is removed by rotary evaporation, and the product is dried under vacuum to obtain an orange solid brominated monomer BDTOT-Br.

8. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step three, the inert gas is either nitrogen or argon; the organic solvent is either toluene, ethylbenzene, xylene, chlorobenzene, or dichlorobenzene; the carbonate aqueous solution is either a 2 mol / L potassium carbonate aqueous solution or a sodium carbonate aqueous solution; the palladium catalyst is either tetraphenylphosphine palladium or tridibenzylacetone dipalladium; the phosphine ligand is either triphenylphosphine, tri-o-tolylphosphine, tri-2-furanylphosphine, or 2-di-tert-butylphosphine biphenyl; the amount of palladium catalyst is 0.1-10% of the molar amount of the brominated monomer BDTOT-Br, preferably 2.6%; the molar ratio of palladium catalyst to phosphine ligand is 1:3-8, preferably 1:4; the temperature of the Suzuki coupling copolymerization reaction is 80-120°C, preferably 120°C, and the reaction time is 8-48 hours, preferably 24 hours.

9. A method for preparing an N-type polymer semiconductor material according to claim 3, characterized in that: In step three, the post-processing is as follows: After the reaction is completed, the mixture is cooled to room temperature, and the reaction system is poured into methanol to precipitate the solid. The polymer precipitates as a brownish-black solid. The solid polymer is collected by filtration, and the solid polymer is extracted sequentially with methanol, acetone, and n-hexane to remove unreacted monomers, catalyst residues, and low molecular weight oligomers. Finally, the target product is extracted with chloroform, and the chloroform solution of the target product is concentrated by rotary evaporation. The concentrate is poured into methanol, and the polymer solid precipitates again. The solid is collected by suction filtration and dried to obtain the brownish-black solid target polymer PBDTOT-BTZ.

10. The application of the N-type polymer semiconductor material as described in any one of claims 1 to 2 in the fabrication of organic electronic devices, characterized in that: The organic electronic device is an organic field-effect transistor, and an N-type polymer semiconductor material is used as the active layer of the organic field-effect transistor.

Images