Aza-vinylene bridged bis-isatin polymer, its preparation method and application

Abstract

This invention discloses a azeoethylene-bridged bis(isoindigo) polymer, its preparation method, and its applications. The structural formula of the azeoethylene-bridged bis(isoindigo) polymer of this invention is shown in Formula I, where R... 1 and R 2 Selected from C 10 -C 100 At least one of straight-chain or branched alkyl groups, where n is 5 to 200. The polymer shown in Formula I of this invention is prepared by monomer preparation via Stille coupling reaction and Aldol reaction of the substrate, followed by conjugation coupling of the monomer. The synthetic route of this invention is simple and easy to implement, with few synthetic steps, making it suitable for large-scale synthesis. Field-effect transistors prepared using the azeotropic bridged bis(isoindigo) polymer of this invention as the organic semiconductor layer exhibit high mobility and on / off ratio, with the highest electron mobility reaching 1.65 cm⁻¹. 2 ·V ‑1 ·s ‑1 The highest hole mobility was 0.75 cm. 2 ·V ‑1 ·s ‑1 The polymer of this invention has promising applications in organic field-effect devices.

Description

Technical Field

[0001] This invention belongs to the field of organic semiconductor materials technology, specifically relating to a ethylene-bridged bis(isoindigo) polymer and its preparation method and application, and more specifically to a ethylene-bridged bis(isoindigo) polymer and its preparation method and field-effect transistor. Background Technology

[0002] Polymer field-effect transistors (PFETs) are electronic components that use polymer semiconductor materials as active components and control the conductivity of the materials through an electric field to perform signal conversion and amplification. They are an important application derived from the highly delocalized electronic system on the polymer molecular backbone. High-performance PFETs have great potential applications in wearable electronics, flexible displays, and smart sensing. Their successful application will inevitably promote technological innovation in many fields such as information, energy, and life sciences, and will have a profound impact on economic development and social progress. Compared with traditional inorganic and organic small-molecule semiconductor materials, polymer semiconductor materials have advantages such as a wide availability of raw materials and simple synthesis processes. They also possess superior programmable characteristics in terms of structure and performance, as well as weak van der Waals forces, solubility, assemblability, and ease of solution processing, thus enabling the large-scale manufacturing of lightweight, flexible electronic devices. Therefore, since its inception, it has received widespread attention from researchers and industry and is currently one of the focal points and hot topics in the field of organic electronics research.

[0003] The polymer semiconductor layer is the core component of PFETs (Polymer Field-Effect Transistors), and its properties determine the performance of the field-effect transistor. Therefore, designing and synthesizing high-performance polymer semiconductor materials is the foundation and prerequisite for the widespread application of polymer field-effect transistors. Similar to organic small-molecule field-effect transistors, the performance parameters of PFETs mainly include mobility (μ) and on / off ratio (IL). on / I off ) and threshold voltage (V T The higher the values ​​of mobility and on / off ratio, the better the performance of PFETs, while the higher the threshold voltage (V). TH The closer the PFET is to zero volts, the better, as such PFETs will be more energy-efficient. After decades of development, significant progress has been made in the research of polymer semiconductor materials and their PFETs. However, the mobility and other properties of existing polymer semiconductor materials and PFETs still cannot meet the needs of widespread applications, making the continued development of new polymer materials of great importance. Summary of the Invention

[0004] The purpose of this invention is to provide a azeotropic bridging bisisodinin polymer, its preparation method, and its application.

[0005] This invention provides a polymer with the structural formula shown in Formula I:

[0006]

[0007] In formula I, R 1 and R 2 Selected from C5-C 80 At least one of straight-chain or branched alkyl groups;

[0008] n ranges from 5 to 200.

[0009] The polymer shown in Formula I of this invention is also known as the azirethylene-bridged diisodigo polymer.

[0010] In the polymer formula I mentioned above, R 1 and R 2 Selected from C 10 -C 50 At least one of straight-chain or branched alkyl groups;

[0011] n is between 10 and 100.

[0012] In the polymer formula I mentioned above, R 1 and R 2 Selected from C 15 -C 40 At least one of straight-chain or branched alkyl groups;

[0013] n can be 30 to 80, specifically 40 to 50.

[0014] In the polymer formula I mentioned above, R 1 and R 2 Selected from 4-decyltetradecyl;

[0015] n is 50 and / or 40.

[0016] In the polymer formula I described above, Ar is selected from at least one of the groups shown in the following structural formulas:

[0017]

[0018] In this invention, the structural formula of the polymer is specifically shown in the following formulas: PNFFN-DTE and PNCCN-BT.

[0019]

[0020] Among the various types,

[0021] The present invention also provides a method for preparing the polymer shown in Formula I above, comprising the following steps:

[0022] 1) In the presence of a palladium catalyst and ligand, the compound shown in Formula II and the compound shown in Formula III were subjected to a Stille reaction, and the reaction was completed to obtain the synthetic intermediate shown in Formula IV.

[0023]

[0024]

[0025] In formulas II and IV, R 1 The definition of R in Equation I 1 Same definition;

[0026] In formula III, R 3 It is at least one of C1 and C4 straight-chain alkyl groups;

[0027] 2) In the presence of organic acids, the compound shown in Formula IV and the compound shown in Formula V are subjected to an Aldol reaction, and the monomer shown in Formula VI is obtained after the reaction is complete.

[0028]

[0029] In equation V, R 2 The definition of R in Equation I 2 Same definition;

[0030] In equation VI, R 1 and R 2 The definition of R in Equation I 1 and R 2 Same definition;

[0031] 3) In an inert atmosphere, in the presence of palladium reagent and ligand, the compound shown in formula VI and the compound shown in formula VII react to obtain the conjugated polymer shown in formula I;

[0032] In equation VII, R 4 It is at least one of C1 and C4 straight-chain alkyl groups; the definition of Ar is the same as R in Formula I. 2 The definitions are the same.

[0033] In the above method, the palladium catalyst is selected from di(dibenzylacetone)palladium and / or tri(dibenzylacetone)dipalladium;

[0034] The ligand is tris(o-tolyl)phosphine and / or triphenylphosphine;

[0035] The molar ratio of the compound shown in Formula II to the compound shown in Formula III can be 1:0.30 to 0.50, specifically 1:0.454;

[0036] The amount of palladium catalyst used is 1% to 15% of the molar amount of the compound shown in Formula II, specifically 3.15%.

[0037] The amount of the phosphine ligand used is 10% to 40% of the molar amount of the compound shown in Formula II, specifically 14.9%;

[0038] In the Stille reaction, the reaction temperature can be 60℃~120℃, preferably 80℃~110℃, and more preferably 100℃, 80℃~100℃ or 100℃~110℃;

[0039] The time can be 10 hours to 48 hours, preferably 12 hours to 36 hours, and more preferably 12 hours, 12 hours to 24 hours or 12 hours to 36 hours;

[0040] The Stille reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere;

[0041] The Stille reaction is carried out in a solvent; the solvent is specifically selected from tetrahydrofuran and / or toluene; the amount of solvent used is sufficient to completely dissolve the reactants.

[0042] In the above method, the organic acid is p-toluenesulfonic acid and / or p-toluenesulfonic acid monohydrate;

[0043] The molar ratio of the compound shown in Formula V to the compound shown in Formula IV can be 1:0.30 to 0.50, specifically 1:0.47, 1:0.30 to 0.47, 1:0.47 to 0.50, or 1:0.45 to 0.50. The molar ratio of the compound shown in Formula V to the organic acid can be 1:0.05 to 0.30, specifically 1:0.18, 1:0.18 to 0.30, 1:0.05 to 0.18, or 1:0.15 to 0.25.

[0044] In the Aldol reaction, the reaction temperature can be 60℃~120℃, preferably 80℃~100℃, and specifically 90℃, 90℃~100℃, 80℃~90℃ or 85℃~95℃;

[0045] The time can be 12 hours to 60 hours, preferably 18 hours to 48 hours, specifically 24 hours, 18 hours to 24 hours, 24 hours to 48 hours or 20 hours to 36 hours;

[0046] The Aldol reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere;

[0047] The Aldol reaction is carried out in a solvent; the solvent is specifically selected from at least one of toluene, xylene, and chlorobenzene; the amount of solvent used is sufficient to completely dissolve the reactants.

[0048] In the above method, in step (3), the palladium reagent is di(dibenzylacetone)palladium and / or tri(dibenzylacetone)dipalladium;

[0049] The ligand is at least one of tris(o-tolyl)phosphine, triphenylphosphine, and triphenylarsine; preferably tris(o-tolyl)phosphine; the molar ratio of the compound shown in Formula VI to the compound shown in Formula VII, the palladium catalyst, and the ligand is 1:0.98-1.02:0.01-0.10:0.10-0.40, specifically 1:1.0:0.0328:0.296;

[0050] In the reaction, the reaction temperature can be 80℃~140℃, preferably 100℃~130℃, and more preferably 115℃, 115℃~130℃, 100℃~115℃ or 110℃~120℃.

[0051] The time is 0.01 hours to 36 hours, preferably 0.1 hours to 24 hours, and more preferably 12 hours, 0.1 hours to 12 hours, 12 hours to 24 hours or 10 hours to 20 hours;

[0052] The reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere;

[0053] The reaction is carried out in a solvent; the solvent is specifically selected from toluene and / or chlorobenzene; the amount of solvent used is sufficient to completely dissolve the reactants.

[0054] In this invention, the post-processing methods for each reaction in the above preparation method are carried out in accordance with conventional methods in the art.

[0055] The polymer shown in Formula I of this invention is used in the fabrication of organic effect transistors.

[0056] The present invention further provides an organic field-effect transistor, wherein the organic semiconductor layer of the organic field-effect transistor is made of the polymer shown in Formula I above.

[0057] In the aforementioned organic field-effect transistor, the thickness of the organic semiconductor layer can be specifically 10–50 nm, specifically 30 nm, 10–30 nm, 30–50 nm, or 20–40 nm.

[0058] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0059] 1. The raw materials for synthesizing the azirene-bridged diisodigo polymer of the present invention can be easily synthesized or purchased in large quantities from commercial channels, making it suitable for large-scale synthesis.

[0060] 2. The azeotropic bisisodigo polymer of this invention possesses a broad UV-Vis absorption spectrum, excellent thermal stability, and good film-forming properties, and holds promise for the fabrication of high-performance polymer field-effect transistor devices via solution processing.

[0061] 3. The field-effect transistor fabricated using the nitride-bridged bis(isoindigo) polymer as the semiconductor layer in this invention exhibits excellent electron / hole mobility (μ). e / μ h (Optimal is μ) e / μ h It is 1.65 / 0.75cm 2 V -1 s -1 It has broad application prospects. Attached Figure Description

[0062] Figure 1 This is a synthetic route diagram of the azirethylene-bridged bisisodinoindigo polymer shown in Formula I of this invention.

[0063] Figure 2 This is a synthetic route diagram of the polymers PNCCN-DTE and PNCCN-BT described in Examples 1 and 2 of the present invention.

[0064] Figure 3 The images show the UV-Vis absorption spectra of the polymers PNCCN-DTE and PNCCN-BT chlorobenzene solutions described in Examples 1 and 2 of this invention. Absorbance (au): normalized absorption intensity; wavelength (nm): wavelength (nanometers).

[0065] Figure 4 The images show the UV-Vis absorption spectra of the polymer PNCCN-DTE and PNCCN-BT films described in Examples 1 and 2 of this invention. Absorbance (au): normalized absorption intensity; wavelength (nm): wavelength (nanometers).

[0066] Figure 5 Thermogravimetric analysis curves of polymers PNCCN-DTE and PNCCN-BT described in Examples 1 and 2 of this invention. Weight (wt%): mass percentage; Temperature (°C): temperature (degrees Celsius).

[0067] Figure 6This is a schematic diagram of the top-gate-bottom-contact (TGBC) PFET structure provided by the present invention. Wherein: Au: gold; Al: aluminum; CYTOP: perfluorinated (1-butenyl vinyl ether) polymer; PVA: polyvinyl alcohol; PET: polyethylene terephthalate; Polymer semiconductor: polymer (PNCCN-DTE or PNCCN-BT).

[0068] Figure 7 and Figure 8 The figures show the output transfer characteristic curves and output characteristic curves of the representative polymer PNCCN-DTE and PNCCN-BT field-effect transistors provided by this invention; wherein, |I DS 1 / 2 |[A] 1 / 2 :|current| 1 / 2 [ampere] 1 / 2 V G [V]: Gate voltage [volts]; I DS [A]: Current [Ampere]; V DS [V]: Source-drain voltage [volts]. Detailed Implementation

[0069] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0070] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0071] The reaction substrates 1 and 4 used in the following examples were synthesized according to the literature Adv. Electron. Mater. 2017, 1700078 and Chem. Mater. 2016, 28, 2209-2218, respectively. All other reaction substrates, solvents and catalysts used were commercially available.

[0072] Example 1: Synthesis of polymer PNCCN-DTE (in Formula I, R) 1 and R 2 The structural unit is 4-decyltetradecyl, and Ar is (trans)-1,2-bis(thiophen-2-yl)ethylene. The synthetic route is as follows: Figure 2 (As shown)

[0073] 1) Synthesis of compound 3 as shown in formula VI

[0074] The contents of 6-bromo-1-(4-decyltetradecyl)indoline-2,3-dione (i.e. Figure 2A degassed toluene solution (40 mL) of (trans)-1,2-bis(tributyltinyl)ethylene (compound 2, 0.715 g, 1.18 mmol), tris(dibenzylacetone)dipalladium (75.0 mg, 0.082 mmol), and tris(o-tolyl)phosphine (118.0 mg, 0.388 mmol) was deoxygenated at low temperature under argon atmosphere. The reaction system was heated to 100 °C and stirred for 12 hours under argon protection. After cooling to room temperature, the mixture was poured into water and extracted three times with dichloromethane. After drying with sodium sulfate and removing the organic solvent under reduced pressure, the resulting solid residue was purified by silica gel column chromatography and dried under vacuum at room temperature (25 °C) to give 1.0 g of a red solid product (i.e., compound 3 represented by formula VI). Yield: 86%.

[0075] The structural characterization data are as follows:

[0076] Mass spectrometry: HRMS (m / z): [M+Na] + :1013.8050.

[0077] Hydrogen spectrum: 1 H NMR (300MHz, CD2Cl2) δ (ppm): 7.63 (d, J = 9.0Hz, 2H), 7.31-7.29 (m, 4H), 7.06 (s, 2H), 3.75(t,J=9.0Hz,4H),1.72(m,4H),1.38-1.23(m,78H),0.89-0.84(t,J=7.5Hz,12H).

[0078] Carbon spectrum: 13 C NMR(75MHz, CDCl3)δ(ppm):182.51,158.43,151.59,145.87,132.01,125.94,122.43,117.56,10 7.81,40.68,37.09,33.48,31.89,30.78,30.10,29.68,29.62,29.33,26.63,24.52,22.66,14.08

[0079] 2) Synthesis of compound 5 as shown in formula VI

[0080] A solution containing compound 3 (0.95 g, 0.96 mmol), compound 4 (1.13 g, 2.05 mmol), p-toluenesulfonic acid monohydrate (69 mg, 0.37 mmol), and dehydrated toluene (50 mL) was subjected to low-temperature deoxygenation. The reaction system was heated to 90 °C and stirred for 24 hours under argon protection. After cooling to room temperature, the mixture was poured into water and extracted three times with dichloromethane. After drying with sodium sulfate and removing the organic solvent under reduced pressure, the resulting solid residue was purified by silica gel column chromatography and dried under vacuum at room temperature to give 1.80 g of a red solid product (i.e., compound 5 represented by formula VI). Yield: 91%.

[0081] The structural characterization data are as follows:

[0082] Mass spectrometry: HRMS (m / z): [M+H] + :2052.4696.

[0083] Hydrogen spectrum: 1 H NMR (300MHz, CDCl3) δ (ppm): 9.29 (d, J = 9.0Hz, 2H), 9.26 (d, J = 6.0Hz, 2H), 7.22-7.19 (m, 4H), 7.14 (d, J=9.0Hz,2H),6.90(s,2H),3.90-3.78(m,8H),1.75(m,8H),1.36-1.22(m,156H),0.89-0.83(m,24H).

[0084] Carbon spectrum: 13 C NMR (75MHz, CDCl3) δ (ppm): 168.12, 167.50, 157.35, 145.76, 142.70, 141.4 8,138.60,134.18,130.86,130.64,129.14,121.67,121.60,121.44,114.98 ,105.42,40.50,39.92,37.10,37.07,33.52,31.93,31.91,30.90,30.74,29.72,29.66,29.65,29.36,26.65,24.74,24.64,22.69,22.68,14.13,14.11.

[0085] 3) Synthesis of the polymer PNCCN-DTE shown in Formula I

[0086] Compound 5 (205.5 mg, 0.10 mmol) of Formula VI, compound (trans)-1,2-bis[5-(trimethylstanyl)thiophen-2-yl]ethylene of Formula VII, compound 6a (51.8 mg, 0.10 mmol), tris(dibenzylacetone)dipalladium (3.0 mg, 0.00327 mmol), tris(o-tolyl)phosphine (9.0 mg, 0.0296 mmol), and degassed chlorobenzene (5.0 mL) were added to a reaction flask. After low-temperature deoxygenation under argon atmosphere, the mixture was heated to 115 °C under argon protection for polymerization for 12 hours. After cooling, 200 mL of a methanol / 6M HCl mixture (20:1 v / v) was added, and the mixture was stirred at room temperature for 2 hours and then filtered. The obtained solid was purified by Soxhlet extraction. The extraction solvents were methanol, acetone and n-hexane for 12 hours each, and then chlorobenzene was used to extract 202 mg of the target polymer (i.e. polymer PNCCN-DTE), with a yield of 97%.

[0087] The structural characterization data are as follows:

[0088] Molecular weight: GPC:M n =104.2kDa, PDI=2.44, n=50;

[0089] Elemental analysis: C 138 H 214 N6O4S2, calculated values: C, 79.48; H, 10.34; N, 4.03; detected values: C 79.23, H 10.17, N 3.92.

[0090] The above indicates that the compound has the correct structure and is a polymer, PNCCN-DTE.

[0091] Example 2: Synthesis of polymer PNCCN-BT (in Formula I, R) 1 and R 2 The structure is 4-decyltetradecyl and Ar is a 2,2'-dithiophene structural unit. The synthetic route is as follows: Figure 2 (As shown)

[0092] 1) Synthesis of compound 5 as shown in formula VI

[0093] The synthesis of compound 5 was carried out in accordance with Example 1.

[0094] 2) Synthesis of the polymer PNCCN-BT shown in Formula I

[0095] Compound 5 (205.5 mg, 0.10 mmol) of Formula VI, compound 5,5'-bis(trimethyltinyl)-2,2'-dithiophene of Formula VII, compound 6b (49.2 mg, 0.10 mmol), tris(dibenzylacetone)dipalladium (3.0 mg, 0.00327 mmol), tris(o-tolyl)phosphine (9.0 mg, 0.0296 mmol), and degassed chlorobenzene (5.0 mL) were added to a reaction flask. After low-temperature deoxygenation under argon atmosphere, the mixture was heated to 115 °C under argon protection for polymerization for 12 hours. After cooling, 200 mL of a methanol / 6M HCl mixture (20:1 v / v) was added, and the mixture was stirred at room temperature for 2 hours and filtered. The resulting solid was purified by Soxhlet extraction, with extraction solvents of methanol, acetone, and n-hexane for 12 hours each, followed by extraction with chlorobenzene to obtain 191 mg of the target polymer, with a yield of 93%.

[0096] The structural characterization data are as follows:

[0097] Molecular weight: GPC:M n =82.7kDa, PDI=2.30. n is 40;

[0098] Elemental analysis: C 136 H 212 N6O4S2, calculated values: C, 79.32; H, 10.38; N, 4.08; detected values: C 79.08, H 10.29, N 4.07.

[0099] The above indicates that the compound has the correct structure and is a polymer, PNCCN-BT.

[0100] Example 3: Spectral properties of polymers PNCCN-DTE and PNCCN-BT

[0101] Figure 3 and Figure 4 The UV-Vis absorption spectra of the polymers PNCCN-DTE and PNCCN-BT chlorobenzene solutions and films prepared in Examples 1 and 2 of this invention are shown.

[0102] Depend on Figure 3 It can be seen that the polymer of the present invention exhibits strong absorption in the ultraviolet-visible region and the near-infrared region, indicating that the polymer molecule of the present invention has strong intramolecular charge transfer.

[0103] Depend on Figure 4 It can be seen that the polymer of the present invention exhibits strong ordered aggregation in the film.

[0104] Example 4: Thermal properties of polymers PNCCN-DTE and PNCCN-BT

[0105] Figure 5These are the thermogravimetric curves of polymers PNCCN-DTE and PNCCN-BT prepared in Examples 1 and 2 of this invention.

[0106] Depend on Figure 5 It is known that the decomposition temperatures (5% loss) of the polymers PNCCN-DTE and PNCCN-BT of the present invention are 421°C and 413°C, respectively, indicating that the polymers of the present invention have good thermal stability.

[0107] Example 5: Fabrication and performance of field-effect transistors of polymers PNCCN-DTE and PNCCN-BT.

[0108] Figure 6 This is a schematic diagram of the organic field-effect transistor (PFET) structure used. The fabrication method is as follows: a gold source-drain electrode is prepared on clean polyethylene terephthalate (PET) using a thermal vacuum evaporation method, and then modified with a cesium fluoride (CsF) thin layer. The semiconductor active layer (30 nm) is prepared by spin-coating a 3.0 mg / mL polymer solution (o-dichlorobenzene as solvent). The thin film sample is annealed at 150 °C for 30 minutes in a glove box, followed by spin-coating with CYTOP solution at 2000 rpm and annealing at 100 °C for 30 minutes. Subsequently, a 1 nm aluminum layer is deposited, followed by spin-coating with a 30 mg / mL PVA solution at 1600 rpm and annealing at 110 °C for 90 minutes. The entire device is baked in a vacuum drying oven at 60 °C for 7 hours, and then annealed at 150 °C for 60 minutes. Finally, an aluminum layer with a thickness of approximately 80 nm is deposited as the gate electrode. The field-effect performance of the fabricated TGBC device was tested in air using a Keithley 4200 SCS semiconductor tester.

[0109] Figure 7 and Figure 8 The transfer and output curves of the field-effect transistors fabricated from polymers PNCCN-DTE and PNCCN-BT are shown in the figures. As can be seen from the figures, the organic field-effect transistor device fabricated in this invention exhibits excellent field-effect modulation performance. The carrier mobility can be calculated using the equation:

[0110] I DS =(W / 2L)C i μ(V G –V T ) 2 (sat.,V DS =V G –V T )

[0111] Among them, I DS V is the drain current, μ is the carrier mobility, and V is the drain current. G V is the gate voltage. TWhere W is the threshold voltage, W is the channel width (1400 micrometers), L is the channel length (30 micrometers), and C is the channel width. i It is an insulator capacitor. Utilizing (I DS (sat) 1 / 2 For V G Plot the graph and perform a linear regression. The carrier mobility can be calculated from the slope of the regression line, and V can be obtained from the intersection of the regression line and the X-axis. T The device performance of the PFETs fabricated in the above examples is shown in Table 1.

[0112] The switching ratio can be determined by Figure 7 and Figure 8 The ratio of the maximum to the minimum source-drain current is used to determine this.

[0113] More than 15 organic field-effect transistor devices were fabricated using the polymers PNCCN-DTE and PNCCN-BT of this invention as semiconductor layers. These devices exhibited stable performance, and their representative performance parameters are shown in Table 1.

[0114] Table 1 Performance of Field-Effect Transistor Devices

[0115]

[0116] In summary, the experimental results show that the azeoethylene-bridged bisisodinoindigo polymer of Formula I provided by this invention is an excellent semiconductor material.

[0117] This invention is not limited to the two reported polymer materials, PNCCN-DTE and PNCCN-BT, but can modify different substituents R 1 R 2 Ar and argon can yield a series of novel azirethylene-bridged bis(isoindigo) polymers, and the synthetic route provided in this invention is simple, easy to implement, and has few steps, making it suitable for large-scale synthesis. This has important guiding significance for the further development of high-performance polymer semiconductor materials.

Claims

1. A polymer having the structural formula shown in Formula I: In formula I, R 1 and R 2 Selected from 4-decyltetradecyl; n is 50 or 40; Ar is selected from at least one of the groups shown in the following structural formulas: 。 2. A method for preparing the polymer of Formula I according to claim 1, comprising the following steps: 1) In the presence of palladium catalyst and phosphine ligand, the compound shown in Formula II and the compound shown in Formula III were subjected to Stille coupling reaction, and the synthetic intermediate shown in Formula IV was obtained after the reaction was completed. In formulas II and IV, R 1 The definition of R in Equation I 1 Same definition; In formula III, R 3 It is at least one of C1 and C4 straight-chain alkyl groups; 2) In the presence of organic acids, the compound shown in Formula IV and the compound shown in Formula V are subjected to an Aldol reaction, and the monomer shown in Formula VI is obtained after the reaction is complete. In equation V, R 2 The definition of R in Equation I 2 Same definition; In equation VI, R 1 and R 2 The definition of R in Equation I 1 and R 2 Same definition; 3) In an inert atmosphere, in the presence of palladium reagent and ligand, the compound shown in formula VI and the compound shown in formula VII react to obtain the conjugated polymer shown in formula I; In equation VII, R 4 It is at least one of C1 and C4 straight-chain alkyl groups; the definition of Ar is the same as the definition of Ar in Formula I.

3. The method according to claim 2, characterized in that: The palladium catalyst is selected from di(dibenzylacetone)palladium and / or tri(dibenzylacetone)dipalladium; The phosphine ligand is selected from tris(o-tolyl)phosphine and / or triphenylphosphine; The molar ratio of the compound shown in Formula II to the compound shown in Formula III is 1:0.30~0.50; The amount of palladium catalyst used is 1% to 15% of the molar amount of the compound shown in Formula II. The amount of the phosphine ligand used is 10% to 40% of the molar amount of the compound shown in Formula II; In the Stille reaction, the reaction temperature is 60℃~120℃; The time ranges from 10 to 48 hours; The Stille reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere; The Stille reaction is carried out in a solvent selected from tetrahydrofuran and / or toluene.

4. The method according to claim 2 or 3, characterized in that: The organic acid is p-toluenesulfonic acid and / or p-toluenesulfonic acid monohydrate; The molar ratio of the compound shown in Formula V to the compound shown in Formula IV is 1:0.30~0.50, and the molar ratio of the compound shown in Formula V to the organic acid is 1:0.05~0.

30. In the Aldol reaction, the reaction temperature is 60℃~120℃; The time ranges from 12 hours to 60 hours; The Aldol reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere; The Aldol reaction is carried out in a solvent; the solvent is selected from at least one of toluene, xylene, and chlorobenzene. In step (3), the palladium reagent is di(dibenzylacetone)palladium and / or tri(dibenzylacetone)dipalladium; The ligand is at least one of tris(o-tolyl)phosphine, triphenylphosphine, and triphenylarsine; The molar ratios of the compound shown in Formula VI to the compound shown in Formula VII, the palladium catalyst, and the ligand are 1:0.98~1.02:0.01~0.10:0.10~0.40, respectively. In the reaction, the reaction temperature is 80℃~140℃; The time ranges from 0.01 hours to 36 hours; The reaction is carried out in an inert atmosphere, which is a nitrogen atmosphere and / or an argon atmosphere; The reaction is carried out in a solvent selected from toluene and / or chlorobenzene.

5. The use of the polymer of Formula I as described in claim 1 in the fabrication of organic effect transistors.

6. An organic field-effect transistor, characterized in that: The organic semiconductor layer of the organic field-effect transistor is made of the polymer shown in Formula I according to claim 1; The thickness of the organic semiconductor layer is 10~50nm.

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