Inherently stretchable high mobility conjugated polymers based on indacenodithiophene units, methods of making and use thereof

Abstract

The application discloses an intrinsic stretchable high-mobility conjugated polymer based on an indacenodithiophene unit and a preparation method and application thereof. A structural formula of the organic conjugated polymer provided by the application is shown as formula I. By using a molecular design strategy, a modified spiro-indacenodithiophene unit is introduced into a near-amorphous polymer system to form strong short-range interchain cross points, so that the electrical transmission characteristics and mechanical properties of a thin film are improved. The polymer material provided by the application has simple preparation process, good scalability, and is suitable for preparing wearable electronic devices, flexible sensors, artificial skin and other fields, and has wide application prospect and important industrial value.

Description

Technical Field

[0001] This invention belongs to the field of organic electronics, specifically relating to an intrinsically stretchable high-mobility organic conjugated polymer semiconductor material based on modified indahedral dithiophene structural units, its preparation method, and its application in wearable electronic devices. Background Technology

[0002] In recent years, with the rapid development of wearable devices, AI-powered electronic skin, and implantable medical devices, the demand for stretchable organic electronic materials has been continuously increasing. As an important component of flexible electronics technology, stretchable organic field-effect transistors (OFETs) have become a research hotspot due to their excellent mechanical adaptability and electrical properties. Traditional stretchable electronic devices mainly rely on rigid inorganic silicon devices to achieve limited mechanical stretchability through strain engineering, induced wrinkle structures, or island-bridge designs. However, these methods are complex and difficult to manufacture in large areas at low cost. Therefore, developing organic semiconductor materials with intrinsic stretchability has become one of the key technologies for realizing next-generation wearable electronic devices.

[0003] The design philosophy of intrinsically stretchable organic semiconductor materials mainly focuses on molecular structure modulation. This involves introducing flexible units, dynamic non-covalent bonds, or rigid fused ring structures into the conjugated polymer backbone or side chains to optimize the material's mechanical flexibility and charge transport properties. Existing research largely relies on modification of highly crystalline semiconductor frameworks (such as pyrrolopyrrole dione (DPP) and isoindigo units). While this can achieve a balance between electrical and mechanical properties to some extent, the difficulty in balancing crystalline and amorphous domains often makes it challenging to maintain stable electrical output under high strain conditions. Furthermore, excessively high crystallinity can lead to irreversible cracking under stress, reducing the device's cycling stability.

[0004] Recent studies have found that high charge mobility does not necessarily depend on long-range ordered crystalline structures. Some near-amorphous polymers, such as the IDTBT (indacenodithiophene-co-benzothiadiazole) system, can achieve charge mobility exceeding 1 cm⁻¹ even without a distinct crystalline structure, thanks to their highly rigid main chain backbone, low-energy disorder, and excellent intrachain transport properties. 2 V -1 s -1 The high field-effect mobility. This discovery provides a new approach to the design of intrinsically stretchable semiconductor materials, namely, by maintaining efficient intrachain charge transport while introducing an appropriate amount of short-range interchain interactions, a flexible and stable three-dimensional conductive network can be constructed, thereby significantly improving mechanical properties while ensuring electrical performance.

[0005] However, current research on near-amorphous polymer systems mainly focuses on the bulk properties of the materials, lacking systematic methods to further control the density and distribution of weak interchain interactions to achieve higher-level synergistic optimization of electromechanical properties. Therefore, developing intrinsically stretchable semiconductor materials that can rationally control the density of interchain interaction points while maintaining excellent intrachain transport properties remains of significant scientific and practical value. Summary of the Invention

[0006] The purpose of this invention is to provide an intrinsically stretchable high-mobility conjugated polymer based on spiro-IDT units, its preparation method, and its applications. This polymer is a novel intrinsically stretchable organic conjugated polymer semiconductor material based on the introduction of spiro-IDT structural units into the main chain. By introducing spiro-IDT units with high rigidity and low steric hindrance into a near-amorphous polymer system, the density of short-range cross points between polymer chains can be directionally controlled while maintaining the efficient charge transport characteristics within the main chain, thus achieving both high charge mobility and excellent mechanical stretchability.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an organic conjugated polymer of Formula I:

[0009]

[0010] In Equation I, n is selected from any positive integer;

[0011] R1, R2, R3, and R4 are each independently selected from any one of the following: hydrogen, C1-C50 straight-chain alkyl, C1-C50 alkoxy, C7-C50 aralkyl, and C5-C50 heteroalkyl;

[0012] Ar is selected from any one of substituted or unsubstituted aryl and heteroaryl groups, and the bonding mode within its group is selected from at least one of single bond, double bond and triple bond;

[0013] X1 and X2 are each independently selected from either sulfur or selenium;

[0014] x:y = 1:(1~10).

[0015] Furthermore, R1, R2, R3, and R4 are each independently selected from any one of: hydrogen, C1-C50 straight-chain alkyl groups, and C1-C50 alkoxy groups; the C1-C50 straight-chain alkyl groups refer to straight-chain alkyl groups with a carbon number between 1 and 50, such as C... 16 H 33 The C1-C50 alkoxy groups refer to alkoxy groups with 1 to 50 carbon atoms.

[0016] And / or, the Ar is selected from any one of the groups shown in formulas a to u:

[0017]

[0018] In formulas a to u, the Ar group is represented at the connection position in formula I;

[0019] The ring containing n is an n+2-element ring, and when n equals 3, it is a 5-element ring, and so on.

[0020] In the above-mentioned organic conjugated polymer, the Ar is any one of 2,1,3-benzothiadiazole-4,7-diyl, 2,1,3-benzoselenidediazole-4,7-diyl, and 2,2-diselenophene.

[0021] As an example, in the organic conjugated polymer, n is 3, X1 and X2 are S, and R1, R2, R3, and R4 are all C. 16 H 33 Ar is 2,1,3-benzothiadiazole-4,7-diyl, and x:y is 1:10.

[0022] In a second aspect, the present invention provides a method for preparing the organic conjugated polymer described in any one of the above claims, comprising the following steps:

[0023] In the presence of a catalyst, the compounds shown in Formula II, Formula III, and Formula IV undergo a Suzuki coupling reaction in a solvent under an inert atmosphere to obtain the organic conjugated polymer shown in Formula I.

[0024]

[0025] In Equation II, X1 and n are defined in the same way as in Equation I;

[0026] In Equation III, X2, R1, R2, R3 and R4 are defined in the same way as in Equation I;

[0027] In Formula IIV, Ar is defined the same as in Formula I, and Y is a trialkyltin group or a borate ester group.

[0028] In the above method, the catalyst further comprises a first catalyst and a second catalyst. The first catalyst is composed of a palladium catalyst and a phosphine ligand. The palladium catalyst is selected from at least one of tetra(triphenylphosphine)palladium and tris(dibenzylacetone)dipalladium. The phosphine ligand is selected from at least one of triphenylphosphine, tri-o-tolylphosphine, tris(2-furanyl)phosphine, and 2-(di-tert-butylphosphine)biphenyl. The molar ratio of the palladium catalyst to the phosphine ligand is (0.01-0.5):1, such as 0.25:1. The second catalyst is a phase transfer catalyst, including but not limited to at least one of trioctylmethylammonium chloride (Aliquat 336), benzyltriphenylphosphine, and alkyl polyoxyethylene ethers, specifically Aliquat 336. As an example, the feed ratio of the palladium catalyst to Aliquat 336 is 0.014 mmol: 10 μL.

[0029] The molar ratio of the compound shown in Formula II, the compound shown in Formula III, and the compound shown in Formula IV is 1:n:(n+1), where n is 1 to 10, such as n = 10;

[0030] The molar ratio of the palladium catalyst to the compound shown in Formula IV is (0.01–0.1):1, such as 0.05:1.

[0031] In the above method, the reaction temperature of the Suzuki coupling reaction is 80-120°C and the reaction time is 8-48 h, such as reacting at 120°C for 24 h;

[0032] The solvent consists of an organic phase and an aqueous phase. The organic phase is selected from at least one of toluene, tetrahydrofuran, and chlorobenzene. The aqueous phase is an aqueous carbonate solution, such as an organic phase and a 2 mol / L sodium carbonate aqueous solution in a volume ratio of 5:1.

[0033] In the above method, as an example, the inert atmosphere gas is nitrogen.

[0034] The above method further includes the following post-processing steps after the Suzuki coupling reaction: the solution system obtained after the coupling reaction is added dropwise to methanol and filtered to obtain polymer solid; then the polymer solid is extracted sequentially with methanol, acetone and n-hexane; finally, the target product is extracted with chloroform and concentrated by rotary evaporation, and the chloroform containing the target product is added dropwise to methanol to precipitate and filtered to obtain the final product, which is the organic conjugated polymer shown in Formula I.

[0035] Thirdly, the present invention provides compounds of Formula II:

[0036]

[0037]

[0038] In Equation II, n is selected from any positive integer, and X1 is selected from either sulfur or selenium.

[0039] Similarly, the ring containing n is an n+2-element ring, and if n equals 3, it is a 5-element ring, and so on.

[0040] As an example, n is 3 and X1 is S.

[0041] Fourthly, the present invention provides a method for preparing compounds of formula IIs, comprising the following steps:

[0042] 1) In the presence of a base, the compound shown in formula V and the diiodoalkane shown in formula VI undergo a nucleophilic substitution reaction in solvent i to give the compound shown in formula VII.

[0043]

[0044] In equation V, X1 is defined the same as in equation II;

[0045] In equation VI, the definition of n is the same as in equation II;

[0046] In equation VII, X1 and n are defined in the same way as in equation II;

[0047] 2) The compound shown in Formula VII undergoes a bromination reaction with a brominating reagent in solvent ii to obtain the compound shown in Formula II.

[0048] In the above method, further, in step 1), the molar ratio of the compound shown in formula V to the compound shown in formula VI is 1:(2-9), preferably 1:2.2;

[0049] The base is sodium tert-butoxide, and the molar ratio of the compound shown in Formula V to sodium tert-butoxide is 1:(4-20), such as 1:6;

[0050] The nucleophilic substitution reaction is carried out at a temperature of 70–120°C for a reaction time of 1–24 h, such as at 90°C for 6 hours.

[0051] The solvent is dimethyl sulfoxide;

[0052] In step 2), the brominating agent is N-bromosuccinimide, and the molar ratio of the compound shown in formula VII to N-bromosuccinimide is 1:(2-3), such as 1:2.11;

[0053] The bromination reaction is carried out in the presence of triethylamine, and the amount of triethylamine added is controlled at one drop of triethylamine for every 0.53 mol of the compound shown in Formula VII;

[0054] Solvent ii is tetrahydrofuran;

[0055] The bromination reaction is carried out at a temperature of 15–40°C. If the reaction is carried out at 30°C, the reaction is monitored by thin-layer column chromatography and N-bromosuccinimide is added as needed until the substrate is completely converted to the dibromo product. The reaction time is 2–3 hours.

[0056] The organic conjugated polymer of this invention exhibits excellent electrical and mechanical properties: the highest measured mobility of a bottom-contact, top-gate organic field-effect device structure is 6.15 cm⁻¹. 2 V -1 s -1 Superior to most existing intrinsically stretchable semiconductor materials, the polymer film retains over 90% of its initial current value in 100% single strain and 3000-cycle tests with 50% strain, effectively solving the problems of cracking and sharp decline in mobility in traditional polymer semiconductors under high strain conditions. No additional additives or elastomer materials are needed for its subsequent application in flexible devices.

[0057] Fifthly, the present invention provides the application of the organic conjugated polymer of Formula I as described in any of the preceding claims as a stretchable organic semiconductor material.

[0058] In the above applications, the stretchable organic semiconductor material is further used to prepare any one of organic field-effect transistors, organic photovoltaic devices, and organic light-emitting diodes; specifically, the organic conjugated polymer shown in Formula I is used to prepare the active layer material of the device.

[0059] The present invention has the following advantages:

[0060] 1. Excellent charge mobility: The polymer material prepared by this invention exhibits a field-effect mobility of up to 6.15 cm⁻¹ at room temperature. 2 V -1 s -1 It outperforms most existing intrinsically stretchable semiconductor materials and can meet the application requirements of high-performance organic electronic devices.

[0061] 2. Excellent mechanical tensile properties: The polymer film can still maintain more than 90% of the initial current value in 100% single strain and 3000 cycles of 50% strain, which effectively solves the problem that traditional polymer semiconductors are prone to cracking and rapid decline in mobility under large strain conditions.

[0062] 3. Scientific and rational molecular design: By introducing spiro-IDT units, this invention cleverly increases the density of short-range cross points between chains while maintaining the coplanarity of the main chain and the efficient charge transport capability within the chain, forming a weakly ordered three-dimensional network structure, thus taking into account both high mobility and high stretchability.

[0063] 4. The preparation method is simple and controllable: The present invention adopts the conventional Stille or Suzuki coupling reaction, which has mild conditions, simple steps, and wide availability of raw materials. It has good scalability and is easy to realize large-scale preparation.

[0064] 5. Wide range of applications: The polymer material of this invention can be widely used in various high-end flexible electronic device fields such as stretchable organic field-effect transistors, organic integrated circuits, flexible sensors, and artificial skin, and has important application prospects.

[0065] 6. Good environmental and device stability: The polymer material has high thermal stability (5% weight loss temperature exceeds 400℃) and exhibits excellent device stability in air environment testing, making it suitable for practical applications with high durability requirements. Attached Figure Description

[0066] Figure 1 This is a flowchart illustrating the preparation process of the compound described in Formula II in Example 1 of the present invention.

[0067] Figure 2 The compound of formula II in Example 1 of this invention 1 H-NMR spectrum.

[0068] Figure 3 The compound of formula II in Example 1 of this invention 13 C-NMR spectrum.

[0069] Figure 4 This is a flowchart illustrating the preparation process of the polymer described in Formula I in Example 2 of the present invention.

[0070] Figure 5 This is a structural diagram of a conjugated polymer field-effect transistor device based on Embodiment 3 of the present invention.

[0071] Figure 6 These are optical microscope images taken after IDTBT and IDTBT10Ring5 polymer films were transferred onto a PDMS substrate and stretched to a certain scale.

[0072] Figure 7 The transfer curves of two polymer films, IDTBT and IDTBT10Ring5, are compared after being stretched to 100% in a single operation.

[0073] Figure 8 The transfer curves of two polymer films, IDTBT and IDTBT10Ring5, were compared after being transferred to a PDMS substrate and subjected to 3000 cycles of cyclic stretching at a 50% stretching ratio.

[0074] Figure 9This is a structural diagram of a conjugated polymer field-effect transistor device based on Embodiment 4 of the present invention.

[0075] Figure 10 The transfer curves are for two polymer field-effect transistors, IDTBT10Ring5 and IDTBT, based on Embodiment 4 of the present invention. Detailed Implementation

[0076] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0077] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0078] Example 1: Synthesis of the compound shown in Formula II (X1 is S, n is 3)

[0079] The specific reaction steps and conditions are as follows:

[0080] Chemical reaction flow chart as follows Figure 1 As shown, compound V (0.50 g, 1.88 mmol, X1 being S) was suspended in anhydrous dimethyl sulfoxide (DMSO, 20 mL), and sodium tert-butoxide (1.08 g, 11.26 mmol) was added in portions. The reaction mixture was heated to 90 °C for 1 hour, followed by the dropwise addition of 1,4-diiodobutane (1.75 g, 5.63 mmol). After the addition was complete, the reaction mixture was heated at 90 °C for another 3 hours, and then poured into ice water. The precipitate was collected by filtration and washed with water and methanol to give a deep yellow solid. The crude product was purified by rapid column chromatography to give a light yellow powder, compound VIII (0.26 g, yield: 37.0%).

[0081] Then, compound VII (0.20 g, 0.53 mmol) was dissolved in 20 mL of tetrahydrofuran, and one drop of triethylamine was added. N-bromosuccinimide (0.20 g, 1.12 mmol) was added in an ice-water bath. The reaction was carried out at 30 °C in the dark. Samples were taken every half hour to monitor the reaction progress using thin-layer column chromatography, and N-bromosuccinimide was added as needed until the substrate was completely converted to dibromoproduct II. The reaction was then stopped, and the mixture was poured into water. The precipitate was collected by filtration, washed with water, and recrystallized from acetone to give a pale yellow compound II (0.14 g, yield: 49.2%).

[0082] The structural verification data is as follows:

[0083] 1 H NMR (400MHz, CDCl3) δ (ppm): 7.30 (s, 2H), 7.02 (s, 2H), 2.14-2.06 (m, 12H), 1.92-1.88 (m, 4H);

[0084] 13 C NMR (101MHz, CD2Cl2) δ (ppm): 156.7, 153.8, 140.4, 134.9, 125.0, 113.3, 112.8, 57.4, 37.8, 26.0.

[0085] MALDI-FTICR-MSm / z:[M] + The calculated value is C 24 H 20 Br2S2: 531.9353; Molecular ion peak position: 529.9368.

[0086] Elemental analysis: The calculated value is C 24 H 20 Br2S2: C, 54.15; H, 3.79; S, 12.04; Measured values: C, 53.79; H, 3.72; S, 11.94.

[0087] 1 H-NMR spectrum and 13 C-NMR spectrum can be seen Figure 2-3 .

[0088] As can be seen from the above, the structure of the product is correct.

[0089] Example 2: Synthesis of the polymer shown in Formula I (n is 3, X1 and X2 are S, R1, R2, R3, and R4 are all C) 16 H 33 Ar is 2,1,3-benzothiadiazole-4,7-diyl, x:y is 1:10)

[0090] Chemical reaction flow chart as follows Figure 4 As shown, the compounds II (14.10 mg, 0.026 mmol) and III (350.00 mg, 0.26 mmol) obtained in Example 1 of this invention (n is 3, X1 and X2 are S, and R1, R2, R3 and R4 are all C) 16 H 33), and 4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)benzo[c][1,2,5]thiadiazole (113.01 mg, 0.29 mmol) were dissolved in 6.0 mL of toluene and 1.2 mL of 2 M sodium carbonate aqueous solution. The mixture was bubbled under nitrogen for 10 min, and then tris(dibenzylacetone)dipalladium (0.014 mmol) catalyst, tri-o-tolylphosphine ligand (0.058 mmol), and Aliquat 336 phase transfer catalyst (10 μL) were added. The reaction tube was purged to replace the nitrogen atmosphere, and the reaction was carried out at 120 °C for 24 h. After cooling the reaction system to room temperature, the solid was poured into 100 mL of methanol to precipitate and filtered. The obtained polymer solid was successively extracted with methanol, acetone and n-hexane by Soxhlet extraction to remove the polymer solid. Finally, the target product was extracted with chloroform. The chloroform solution of the target product was concentrated by rotary evaporation and poured into 100 mL of methanol to precipitate the polymer solid. The solid was filtered and dried to obtain polymer I (328.4 mg, yield: 92.1%).

[0091] The structural verification data is as follows:

[0092] Elemental analysis: The calculated value is C 890 H 1402 N 22 S 33 :C,79.36;H,10.49;N,2.29;S,7.86;Measured values:C,79.00;H,10.39,N,2.69,S,7.81.

[0093] As can be seen from the above, the structure of the product is correct, and it is the polymer shown in Formula I. It is denoted as: IDTBT10Ring5.

[0094]

[0095] Example 3

[0096] This embodiment provides a specific application of the p-type polymer film of Example 2, after stretching, as an active layer material for a field-effect transistor:

[0097] The polymer of Formula I prepared in Example 2 was formulated into a 5 mg / mL chlorobenzene solution for later use. 20 μL of this solution was spin-coated onto a 1 × 1 cm OTS-modified Si / SiO2 wafer at 2 k r / min using a pipette. The film was then lifted from a PDMS substrate (precursor: crosslinking agent = 12:1, v:v) and stretched to different ratios before being transferred onto a Si / SiO2 wafer pre-printed with 50 μm channel gold electrodes. After annealing at 150 °C for 10 min, it was used as the active layer of a field-effect transistor (the structure of the field-effect transistor is shown below). Figure 5(As shown); or PDMS with a polymer I film is placed on a stretching machine and cyclically stretched at 50% strain for different numbers of cycles, then tightly bonded to a Si / SiO2 wafer pre-printed with 50μm channel intercalated gold electrodes for transfer, and the migration rate is tested after annealing at 150℃ for 10 min. IDTBT is used as a control.

[0098] IDTBT, as a comparative polymer, is a polymer that was blended without the addition of spirocyclic structural units as shown in Formula II, and the reaction conditions were the same as those for polymer I (x:y = 0:1).

[0099]

[0100] Figure 6 These are optical microscope images taken after IDTBT10Ring5 and IDTBT polymer films were transferred onto a PDMS substrate and stretched to a certain scale.

[0101] Figure 7 The transfer curves of two polymer films, IDTBT and IDTBT10Ring5, are compared after being stretched to 100% in a single operation.

[0102] Figure 8 The transfer curves of two polymer films, IDTBT and IDTBT10Ring5, were compared after being transferred to a PDMS substrate and subjected to 3000 cycles of cyclic stretching at a 50% stretching ratio.

[0103] Depend on Figures 6-8 It can be seen that, compared with IDTBT, the polymer film made from the polymer of the present invention has better stretchability.

[0104] Example 4

[0105] This embodiment provides a bottom-contact, top-gate organic field-effect transistor constructed from polymer IDTBT10Ring5 as described in Example 2 (e.g., ...). Figure 9 Specific applications shown in the figure:

[0106] In a nitrogen glove box, the polymer of Formula I prepared in Example 2 was prepared into a 5 mg / mL chlorobenzene solution for later use. Before semiconductor deposition, Corning glass was modified with OTS (octadecyltrichlorosilane), and a thin layer of CuSCN was applied to the pre-patterned Au electrode to promote hole injection. 20 μL of the polymer solution was spin-coated at 2 kr / min onto the CuSCN-treated Corning glass with the pre-patterned Au electrode using a pipette, and annealed at 260°C for 20 minutes under nitrogen. Then, a fluoropolymer gate dielectric (Cytop) was deposited, and finally, an aluminum gate was deposited using vacuum evaporation to complete the device fabrication.

[0107] Figure 10 The transfer curves are for two polymer field-effect transistors, IDTBT10Ring5 and IDTBT, based on Embodiment 4 of the present invention.

[0108] Test results (e.g.) Figure 10 As shown in the figure, the highest hole mobility of IDTBT10 Ring5 is 6.15 cm. 2 V -1 s -1 It outperforms most existing organic intrinsically stretchable polymer semiconductor materials, demonstrating its potential applications in various high-end flexible electronic devices such as organic integrated circuits, flexible sensors, and artificial skin.

[0109] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. The organic conjugated polymer shown in Formula I: In Equation I, n=3; R1, R2, R3, and R4 are each independently selected from any one of the following: hydrogen, C1-C50 straight-chain alkyl, C1-C50 alkoxy, and C7-C50 aralkyl. Ar is selected from any one of substituted or unsubstituted aryl and heteroaryl groups, and the bonding mode within its group is selected from at least one of single bond, double bond and triple bond; X1 and X2 are each independently selected from either sulfur or selenium; x:y=1:(1~10) 2. The organic conjugated polymer according to claim 1, characterized in that: R1, R2, R3, and R4 are each independently selected from any one of hydrogen, C1-C50 straight-chain alkyl groups, and C1-C50 alkoxy groups; And / or, the Ar is selected from any one of the groups shown in formulas a to u: In formula a~u, This indicates the connection position of the Ar group in Formula I.

3. A method for preparing the organic conjugated polymer according to any one of claims 1-2, comprising the following steps: In the presence of a catalyst, the compounds shown in Formula II, Formula III, and Formula IV undergo a Suzuki coupling reaction in a solvent under an inert atmosphere to obtain the organic conjugated polymer shown in Formula I. In Equation II, X1 and n are defined in the same way as in Equation I; In Equation III, X2, R1, R2, R3 and R4 are defined in the same way as in Equation I; In Formula IV, Ar is defined the same as in Formula I, and Y is a trialkyltin group or a borate ester group.

4. The method according to claim 3, characterized in that: The catalyst includes a first catalyst and a second catalyst; The first catalyst consists of a palladium catalyst and a phosphine ligand; The palladium catalyst is selected from at least one of tetra(triphenylphosphine)palladium and tris(dibenzylacetone)dipalladium; The phosphine ligand is selected from at least one of triphenylphosphine, tri-o-tolylphosphine, tris(2-furanyl)phosphine and 2-(di-tert-butylphosphine)biphenyl; The molar ratio of the palladium catalyst to the phosphine ligand is (0.01–0.5):1; The second catalyst is a phase transfer catalyst; The phase transfer catalyst is selected from at least one of trioctylmethylammonium chloride, benzyltriphenylphosphine salt, and alkyl polyoxyethylene ethers; The molar ratio of the compound shown in Formula II, the compound shown in Formula III, and the compound shown in Formula IV is 1 : n : (n+1), where n is 1 to 10; The molar ratio of the palladium catalyst to the compound of formula IV is (0.01–0.1):

1.

5. The method according to any one of claims 3-4, characterized in that: The reaction temperature of the Suzuki coupling reaction is 80–120°C, and the reaction time is 8–48 h. The solvent consists of an organic phase and an aqueous phase, wherein the organic phase is selected from at least one of toluene, tetrahydrofuran, and chlorobenzene, and the aqueous phase is an aqueous carbonate solution.

6. The compound shown in Formula II: In Formula II, n=3, and X1 is selected from either sulfur or selenium.

7. A method for preparing the compound of claim 6, comprising the following steps: 1) In the presence of a base, the compound shown in formula V and the diiodoalkane shown in formula VI undergo a nucleophilic substitution reaction in solvent i to give the compound shown in formula VII; In equation V, X1 is defined the same as in equation II; In equation VI, the definition of n is the same as in equation II; In equation VII, X1 and n are defined in the same way as in equation II; 2) The compound shown in Formula VII undergoes a bromination reaction with a brominating reagent in solvent ii to obtain the compound shown in Formula II.

8. The method according to claim 7, characterized in that: In step 1), the molar ratio of the compound shown in formula V to the compound shown in formula VI is 1:(2-9); The base is sodium tert-butoxide, and the molar ratio of the compound shown in Formula V to sodium tert-butoxide is 1:(4-20). The nucleophilic substitution reaction is carried out at a temperature of 70–120 °C for a time of 1–24 h. The solvent i is dimethyl sulfoxide; In step 2), the brominating agent is N-bromosuccinimide, and the molar ratio of the compound shown in formula VII to N-bromosuccinimide is 1:(2-3). The bromination reaction was carried out in the presence of triethylamine; Solvent ii is tetrahydrofuran; The bromination reaction is carried out at a temperature of 15–40 °C.

9. The application of the organic conjugated polymer of formula I as described in any one of claims 1-2 as a stretchable organic semiconductor material.

10. The application according to claim 9, characterized in that: The stretchable organic semiconductor material is used to fabricate any one of organic field-effect transistors, organic photovoltaic devices, and organic light-emitting diodes.

11. The application according to claim 10, characterized in that: The organic conjugated polymer shown in Formula I is used to prepare the active layer material of the device.

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