Polymer based on 2, 6-dibromo-4H-cyclopenta [1, 2-B: 5, 4-B] dithiophene-4-ketone as well as preparation method and application thereof

Abstract

The invention provides a polymer based on 2, 6-dibromo-4H-cyclopenta [1, 2-B: 5, 4-B] dithiophene-4-ketone as well as a preparation method and application of the polymer, and belongs to the technical field of organic photoelectric materials. The polymer based on the 2, 6-dibromo-4H-cyclopenta [1, 2-B: 5, 4-B] dithiophene-4-ketone provided by the invention is a polymer P-ODDTO-BT, a polymer P-ODDTO-TT and a polymer P-ODDTO-T with structures shown in a formula I, a formula II and a formula III respectively. The polymer provided by the invention has high carrier mobility on the basis of good thermal stability and photochemical stability, and is beneficial to application in the field of organic semiconductor materials.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically relating to polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, their preparation methods, and applications. Background Technology

[0002] Organic flexible materials and devices have received widespread attention and research in the semiconductor industry over the past 30 years. Among them, organic thin-film transistors (OTFTs) based on organic semiconductors have become one of the important research directions in the field of organic flexible electronics, and can be used in fields such as adhesive sensors, RFID tags, and logic circuits. Compared with traditional silicon-based transistors, OTFTs have the advantages of simple fabrication processes, flexibility, versatility, and low cost. However, their low carrier mobility seriously hinders large-scale commercial applications. To improve the performance of OTFTs, in addition to device optimization, material innovation is also crucial. A well-designed molecular structure of organic semiconductor materials can optimize molecular packing and molecular energy levels, helping to achieve high carrier mobility, thereby improving device performance and expanding its application range.

[0003] 2,6-Dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one possesses advantages such as a rigid planar structure, high thermal stability, and photochemical stability, making it suitable for application in organic optoelectronic materials. However, the carrier mobility of organic semiconductor materials prepared from 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one still needs improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, its preparation method, and its applications. The polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by this invention exhibits good thermal and photochemical stability as well as high carrier mobility, which is beneficial for its application in the field of organic semiconductor materials.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, namely polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T; wherein polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T have the structures shown in Formula I, Formula II, and Formula III, respectively.

[0007]

[0008] In Equations I, II and III, 1 ≤ n ≤ 400 and n is an integer.

[0009] This invention provides a method for preparing the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, comprising the following steps:

[0010] 2,6-Dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one and hydroxylamine hydrochloride were mixed and subjected to a condensation reaction to obtain an oxime derivative.

[0011] The oxime derivatives were mixed with 1-bromo-2-octyldodecane and subjected to a substitution reaction to obtain alkyl-substituted monomeric compounds;

[0012] The alkyl-substituted monomer compound was mixed with a bithiophene organotin reagent and subjected to a first polymerization reaction to obtain the polymer P-ODDTO-BT; the bithiophene organotin reagent was 5,5-bis(trimethyltinyl-2,2'-bithiophene).

[0013] The alkyl-substituted monomer compound was mixed with a bis(trimethyltin)thiophene organotin reagent and subjected to a second polymerization reaction to obtain the polymer P-ODDTO-TT; the bis(trimethyltin)thiophene organotin reagent was 2,5-bis(trimethyltin)-thiophene[3,2-B]thiophene.

[0014] The alkyl-substituted monomer compound was mixed with a thiophene organotin reagent and subjected to a third polymerization reaction to obtain the polymer P-ODDTO-T; the thiophene organotin reagent was 2,5-bis(trimethyltin)thiophene.

[0015] The structural formulas of the oxime derivatives and alkyl-substituted monomer compounds are shown in Formula 1 and Formula 2, respectively:

[0016]

[0017] Preferably, the molar ratio of 2,6-dibromo-4H-cyclopenta[1,2-B:5,4-B]dithiophene-4-one to hydroxylamine hydrochloride is 1:5.

[0018] Preferably, the condensation reaction is carried out at a temperature of 80°C for 24 hours.

[0019] Preferably, the molar ratio of the oxime derivative to 1-bromo-2-octyldodecane is 1:2.5.

[0020] Preferably, the substitution reaction is carried out at a temperature of 60°C for 8–15 hours.

[0021] Preferably, the molar ratio of the alkyl-substituted monomer compound to the bis(thiophene) organotin reagent or the bis(thiophene) organotin reagent or the thiophene organotin reagent is 1:1.

[0022] Preferably, the temperature of the first polymerization reaction, the second polymerization reaction, and the third polymerization reaction is 90°C, and the time is 24 hours.

[0023] This invention provides the application of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one described in the above technical solution in organic thin-film transistors.

[0024] The present invention provides an organic thin-film transistor, wherein the active layer of the organic thin-film transistor is prepared from a polymer based on 2,6-dibromo-4H-cyclopenta[1,2-B:5,4-B]dithiophene-4-one as described in the above technical solution.

[0025] This invention provides polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, namely polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T having the structures shown in Formulas I, II, and III, respectively. The polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by this invention have novel structures and high planarity, which is beneficial for improving carrier mobility. Furthermore, the polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by this invention have a wide spectral absorption range, from the visible light region to the near-infrared region, up to a maximum of 900 nm. Examples show that the OTFTs device prepared from the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by the present invention exhibits a carrier mobility of 1.19 × 10⁻⁶ after annealing at 250 °C for 20 min. -2 cm 2 ·V -1 S -1 This is beneficial for its application in the field of organic semiconductor materials.

[0026] Furthermore, the preparation of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by this invention has abundant raw material sources, simple synthesis steps, and high yield of intermediate alkyl-substituted monomer compounds. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 The proton NMR spectrum of the alkyl-substituted monomeric compound;

[0029] Figure 2 Carbon spectra of alkyl-substituted monomeric compounds;

[0030] Figure 3 High-resolution mass spectra of alkyl-substituted monomeric compounds;

[0031] Figure 4 The UV-Vis absorption spectrum of polymer P-ODDTO-BT in chloroform;

[0032] Figure 5 The UV-Vis absorption spectrum of polymer P-ODDTO-TT in chloroform;

[0033] Figure 6 The UV-Vis absorption spectrum of polymer P-ODDTO-T in chloroform;

[0034] Figure 7 A schematic diagram of an organic thin-film transistor with polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T as active layers;

[0035] Figure 8 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures.

[0036] Figure 9 The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures are shown.

[0037] Figure 10 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures.

[0038] Figure 11 The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures are shown.

[0039] Figure 12 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-T as the organic active semiconductor layer at different annealing temperatures.

[0040] Figure 13 The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-T as the organic active semiconductor layer are shown at different annealing temperatures. Detailed Implementation

[0041] This invention provides polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, namely polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T; wherein polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T have the structures shown in Formula I, Formula II, and Formula III, respectively.

[0042]

[0043] In Equations I, II and III, 1 ≤ n ≤ 400 (preferably 10 ≤ n ≤ 200) and n is an integer.

[0044] This invention provides a method for preparing the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, comprising the following steps:

[0045] 2,6-Dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one and hydroxylamine hydrochloride were mixed and subjected to a condensation reaction to obtain an oxime derivative.

[0046] The oxime derivatives were mixed with 1-bromo-2-octyldodecane and subjected to a substitution reaction to obtain alkyl-substituted monomeric compounds;

[0047] The alkyl-substituted monomer compound was mixed with a bithiophene organotin reagent and subjected to a first polymerization reaction to obtain the polymer P-ODDTO-BT; the bithiophene organotin reagent was 5,5-bis(trimethyltinyl-2,2'-bithiophene).

[0048] The alkyl-substituted monomer compound was mixed with a bis(trimethyltin)thiophene organotin reagent and subjected to a second polymerization reaction to obtain the polymer P-ODDTO-TT; the bis(trimethyltin)thiophene organotin reagent was 2,5-bis(trimethyltin)-thiophene[3,2-B]thiophene.

[0049] The alkyl-substituted monomer compound was mixed with a thiophene organotin reagent and subjected to a third polymerization reaction to obtain the polymer P-ODDTO-T; the thiophene organotin reagent was 2,5-bis(trimethyltin)thiophene.

[0050] The structural formulas of the oxime derivatives and alkyl-substituted monomer compounds are shown in Formula 1 and Formula 2, respectively:

[0051]

[0052] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0053] This invention involves mixing 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one and hydroxylamine hydrochloride, and performing a condensation reaction to obtain an oxime derivative. In this invention, the molar ratio of 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one to hydroxylamine hydrochloride is preferably 1:5. Preferably, this invention involves mixing 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, hydroxylamine hydrochloride, pyridine, and ethanol for a condensation reaction. In this invention, the volume ratio of pyridine to ethanol is preferably 1:3. The preferred temperature for the condensation reaction is 80°C, and the preferred time is 24 hours. After the condensation reaction, this invention preferably cools the resulting liquid to room temperature, mixes the cooled liquid with water, performs solid-liquid separation, collects the solid material, and then washes the solid material sequentially with water and alcohol to obtain the oxime derivative. The solid-liquid separation method described in this invention is preferably filtration. The reagent used for alcohol washing in this invention is preferably methanol.

[0054] After obtaining the oxime derivative, the present invention mixes the oxime derivative with 1-bromo-2-octyldodecane to carry out a substitution reaction to obtain an alkyl-substituted monomer compound. In the present invention, the molar ratio of the oxime derivative to 1-bromo-2-octyldodecane is preferably 1:2.5. The present invention preferably mixes the oxime derivative, 1-bromo-2-octyldodecane with potassium carbonate and N,N-dimethylformamide to carry out the substitution reaction. In the present invention, the molar ratio of potassium carbonate to the oxime derivative is preferably 3.28:1.1; the molar ratio of N,N-dimethylformamide to the oxime derivative is preferably 10 mL:0.4 g. The temperature of the substitution reaction in the present invention is preferably 60°C, and the time is preferably 8–15 h, more preferably 10–12 h. The present invention preferably carries out the substitution reaction under stirring conditions. The present invention does not have special limitations on the stirring method and conditions; any stirring method well known to those skilled in the art can be used. Following the substitution reaction, the present invention preferably pours the resulting liquid into water, extracts it with dichloromethane, and collects the organic phase; the obtained organic phase is dried with anhydrous sodium sulfate; the dried material is then concentrated and purified by column chromatography. In the present invention, the concentration is preferably performed under reduced pressure. In the present invention, the eluent used for column chromatography purification is preferably dichloromethane and petroleum ether; the volume ratio of dichloromethane to petroleum ether is preferably 1:1.

[0055] After obtaining the alkyl-substituted monomer compound, the present invention mixes the alkyl-substituted monomer compound with a bithiophene organotin reagent to carry out a first polymerization reaction to obtain the polymer P-ODDTO-BT. In the present invention, the bithiophene organotin reagent is 5,5-bis(trimethyltin)alkyl-2,2'-bithiophene. In the present invention, the molar ratio of the alkyl-substituted monomer compound to the bithiophene organotin reagent is preferably 1:1. The present invention preferably mixes the alkyl-substituted monomer compound, the bithiophene organotin reagent, tris-(diphenylene-BASE-acetone)dipalladium, and tris(o-methylphenyl)phosphine to carry out the first polymerization reaction. In the present invention, the molar ratio of tris-(diphenylene-BASE-acetone)dipalladium, tris(o-methylphenyl)phosphine, and the alkyl-substituted monomer compound is preferably 0.0051:0.0204:0.232. The temperature of the first polymerization reaction of the present invention is preferably 90°C, and the time is preferably 24 hours. The first polymerization reaction of the present invention is preferably carried out under an argon atmosphere. In the embodiments of the present invention, the first polymerization reaction is carried out in a Schlenk flask. Before the first polymerization reaction, the present invention preferably adds a small amount of anhydrous chlorobenzene to a Schlenk flask. In the present invention, the anhydrous chlorobenzene serves as a reaction solvent. After the first polymerization reaction is completed, the present invention preferably cools the resulting reaction solution to room temperature and mixes it with methanol, collects the solid material after solid-liquid separation, washes the obtained solid material with acetone, and then extracts the washed solid material with acetone, n-hexane, chloroform and chlorobenzene respectively. The polymer extracted from chloroform and the polymer extracted from chlorobenzene are collected and concentrated to obtain the polymer P-ODDTO-BT with the structure shown in Formula I.

[0056] After obtaining the alkyl-substituted monomer compound, the present invention mixes the alkyl-substituted monomer compound with a bis(thiophene) organotin reagent to carry out a second polymerization reaction to obtain the polymer P-ODDTO-TT. In the present invention, the bis(thiophene) organotin reagent is 2,5-bis(trimethyltin)-thieno[3,2-B]thiophene. In the present invention, the molar ratio of the alkyl-substituted monomer compound to the bis(thiophene) organotin reagent is preferably 1:1. The present invention preferably mixes the alkyl-substituted monomer compound, the bis(thiophene) organotin reagent with tris-(diphenylene-BASE-acetone)dipalladium and tris(o-methylphenyl)phosphine to carry out the second polymerization reaction. In the present invention, the molar ratio of tris-(diphenylene-BASE-acetone)dipalladium, tris(o-methylphenyl)phosphine and the alkyl-substituted monomer compound is preferably 0.0051:0.0204:0.232. The temperature of the second polymerization reaction of the present invention is preferably 90°C, and the time is preferably 24 h. The second polymerization reaction of the present invention is preferably carried out under an argon atmosphere. In an embodiment of the present invention, the second polymerization reaction is carried out in a Schlenk flask. Before the second polymerization reaction, the present invention preferably adds a small amount of anhydrous chlorobenzene to the Schlenk flask. After the second polymerization reaction is completed, the present invention preferably cools the resulting reaction solution to room temperature and mixes it with methanol, then separates the solid and liquid phases and collects the solid material; the obtained solid material is washed with acetone, and then extracted with acetone, n-hexane, and chloroform respectively; the polymer extracted in chloroform and the polymer extracted in chlorobenzene are collected and concentrated to obtain the polymer P-ODDTO-TT having the structure shown in Formula II.

[0057] After obtaining the alkyl-substituted monomer compound, the present invention mixes the alkyl-substituted monomer compound with a thiophene organotin reagent to carry out a third polymerization reaction to obtain the polymer P-ODDTO-T. In the present invention, the thiophene organotin reagent is 2,5-bis(trimethyltinyl)thiophene. In the present invention, the molar ratio of the alkyl-substituted monomer compound to the thiophene organotin reagent is preferably 1:1. The present invention preferably mixes the alkyl-substituted monomer compound, the thiophene organotin reagent, and tris-(diphenylene-BASE-acetone)dipalladium and tris(o-methylphenyl)phosphine to carry out a second polymerization reaction. In the present invention, the molar ratio of tris-(diphenylene-BASE-acetone)dipalladium, tris(o-methylphenyl)phosphine, and the alkyl-substituted monomer compound is preferably 0.0051:0.0204:0.232. The temperature of the third polymerization reaction of the present invention is preferably 90°C, and the time is preferably 24 hours. The third polymerization reaction of the present invention is preferably carried out under an argon atmosphere. In the embodiments of the present invention, the third polymerization reaction is carried out in a Schlenk flask. Before the third polymerization reaction, the present invention preferably adds a small amount of anhydrous chlorobenzene to a Schlenk flask. After the third polymerization reaction is completed, the present invention preferably cools the resulting reaction solution to room temperature and mixes it with methanol, and collects the solid material after solid-liquid separation; the obtained solid material is washed with acetone, and then extracted with acetone, n-hexane and chloroform respectively, and the polymer extracted from n-hexane and the polymer extracted from chloroform are collected and concentrated to obtain polymer P-ODDTO-T with the structure shown in Formula III.

[0058] The present invention also provides the application of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one described in the above technical solution in organic thin film transistors.

[0059] This invention also provides an organic thin-film transistor, wherein the active layer of the organic thin-film transistor is prepared from a polymer based on 2,6-dibromo-4H-cyclopenta[1,2-B:5,4-B]dithiophene-4-one as described in the above-mentioned technical solution. In this invention, the organic thin-film transistor preferably has a low gate-bottom contact structure. In this invention, the polymer based on 2,6-dibromo-4H-cyclopenta[1,2-B:5,4-B]dithiophene-4-one is preferably used as the active layer of the organic thin-film transistor.

[0060] The organic thin-film transistor of the present invention preferably comprises a substrate, a surface-treated substrate, and an active layer stacked sequentially; the surface-treated substrate preferably comprises a gate electrode and an insulating layer stacked sequentially, and a source electrode and a drain electrode disposed on the surface of the insulating layer. In the present invention, the gate electrode is preferably n-type silicon; the insulating layer is preferably composed of silicon dioxide, and the thickness of the insulating layer is preferably 300 nm; the active layer comprises a polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one. In the present invention, the source electrode and the drain electrode are preferably made of gold.

[0061] The preferred method for fabricating the organic thin-film transistor of the present invention includes the following steps: a silicon dioxide thin film is prepared as an insulating layer on the upper surface of the gate electrode using a thermal generation method; gold is deposited at both ends of the upper surface of the insulating layer using photolithography to form a source electrode and a drain electrode, thereby obtaining a substrate; one side of the source electrode and drain electrode of the substrate is modified with n-octadecyl mercaptan and then immersed in a toluene solution of dodecyltrichlorosilane for surface treatment, thereby obtaining a surface-treated substrate; a chloroform solution of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one is coated onto the upper surface of the surface-treated substrate, and annealed to form an active layer on the upper surface of the surface-treated substrate, thereby obtaining the organic thin-film transistor.

[0062] This invention employs a thermal generation method to prepare a silicon dioxide thin film as an insulating layer on the upper surface of the gate electrode. In this invention, the gate electrode is preferably n-type silicon. In this invention, the thickness of the insulating layer is preferably 300 nm.

[0063] After obtaining the insulating layer, the present invention uses photolithography to deposit gold at both ends of the upper surface of the insulating layer to form source and drain electrodes, thereby obtaining a substrate. In the present invention, the length of the channel of the source and drain electrodes is preferably 1000 μm, and the width is preferably 30 μm.

[0064] After obtaining the substrate, the present invention modifies one side of the source electrode and the drain electrode of the substrate with n-octadecyl mercaptan and then immerses it in a toluene solution of dodecyltrichlorosilane for surface treatment to obtain a surface-treated substrate. In the present invention, the modification preferably includes washing; the washing preferably includes sequential ultrasonic washing and plasma washing; the reagent used for ultrasonic washing preferably includes deionized water, acetone and isopropanol. In the present invention, the surface treatment temperature is preferably 20-35°C, more preferably 25-30°C; the time is preferably 20 min. The surface treatment preferably includes washing and drying. In the present invention, the washing reagent is preferably toluene; the drying is preferably carried out under a nitrogen flow.

[0065] After obtaining the surface-treated substrate, the present invention coats the upper surface of the surface-treated substrate with a chloroform solution of the polymer and performs annealing treatment to form an active layer on the upper surface of the surface-treated substrate, thereby obtaining the organic thin-film transistor. In the chloroform solution of the polymer of the present invention, the concentration of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one is preferably 5 mg / mL. In the present invention, the coating is preferably spin-coating; the spin-coating speed is preferably 3000 rpm, and the time is preferably 60 s. In the present invention, the annealing temperature is preferably 25–200°C, specifically 25°C, 50°C, 100°C, 150°C, or 200°C; the time is preferably 20 min. The annealing treatment of the present invention is preferably performed under a nitrogen atmosphere.

[0066] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0067] In the examples, the "overnight" time is 8 to 15 hours, depending on the extent of the reaction.

[0068] Example 1

[0069] (1) Synthesis of oxime derivatives

[0070]

[0071] Weigh 1.5 g (4.29 mmol) of 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one and 1.49 g (21.5 mmol, 5 eq.) of NH₂OH·HCl into a 100 mL single-necked round-bottom flask, add 4 mL of pyridine and 12 mL of ethanol, and heat the resulting mixture to 80 °C for 24 h. After the reaction is complete, cool the system to room temperature, pour the resulting liquid into 150 mL of water, filter, collect the solid, wash the solid with water and methanol to obtain the oxime derivative (red solid, 1.47 g, which can be used directly in the next step).

[0072] (2) Synthesis of alkyl-substituted monomeric compounds

[0073]

[0074] Weigh out an oxime derivative (0.4 g, 1.1 mmol), 1-bromo-2-octyldodecane (0.99 g, 2.75 mmol), and K₂CO₃ (0.456 g, 3.28 mmol) into a 50 mL round-bottom flask, then add 10 mL of N,N-dimethylformamide (DMF). Heat the resulting mixture to 60 °C and stir overnight. After the reaction is complete, pour the reaction solution into water and extract with dichloromethane, collecting the organic phase. Dry the obtained organic phase with anhydrous sodium sulfate, then concentrate under reduced pressure and purify by column chromatography (eluent: dichloromethane / petroleum ether = 1 / 1, v / v) to obtain an alkyl-substituted monomer compound (0.51 g, yield 71.8%).

[0075] The NMR data of the alkyl-substituted monomer compound are as follows: 1 H NMR (400MHz, CDCl3) δ: 7.33 (s, 1H), 7.17 (s, 1H), 4.26 (d, J = 5.96Hz, 2H), 1.81 (m, 1H), 1.39-1.25 (m, 32H), 0.89-0.86 (m, 6H). 13 C NMR(100MHz, CDCl3)δ:145.35,141.66,139.88,139.02,133.39,127.75,123.40,112.35,111.67,79.38,37.83,3 1.93,31.91,31.32,29.99,29.68,29.65,29.62,29.58,29.37,29.34,26.74,22.70,14.14.HRMS:m / z[M]+calcd.C 29 H 43 Br2NOS2 + ,643.1153;found:643.1200.

[0076] The proton NMR spectrum, carbon NMR spectrum, and high-resolution mass spectrum of the alkyl-substituted monomer compound are shown below. Figure 1 , Figure 2 and Figure 3 As shown.

[0077] (3) Synthesis of polymer P-ODDTO-BT

[0078] The synthesis reaction formula for polymer P-ODDTO-BT is shown below:

[0079]

[0080] An alkyl-substituted monomer compound (150 mg, 0.232 mmol, 1.0 eq.), 5,5-bis(trimethyltinyl)-2,2'-bithiophene (114.28 mg, 0.232 mmol, 1.0 eq.), Pd2(dba)3 (4.67 mg, 0.0051 mmol, 0.0051 eq.), and tris(o-methylphenyl)phosphine (6.21 mg, 0.0204 mmol, 0.08 eq.) were weighed and placed in a 100 mL Schlenk flask, which was then purged three times with argon. 5 mL of anhydrous chlorobenzene was added to the Schlenk flask, and the reaction mixture was reacted at 90 °C for 24 h under an argon atmosphere. After the reaction was completed, the reaction solution was cooled to room temperature, poured into 150 mL of methanol, filtered, and the solid material was collected. The solid material was washed with acetone, and then extracted with acetone, n-hexane, chloroform, and chlorobenzene, respectively. Finally, the polymer extracted from chloroform was concentrated and collected to obtain polymer P-ODDTO-BT (40 mg, yield 39.7%), and the polymer extracted from chlorobenzene was concentrated and collected to obtain polymer P-ODDTO-BT (2.1 mg, yield 2.1%).

[0081] Example 2

[0082] (1) Alkyl-substituted monomer compounds were obtained according to the method and conditions of Example 1.

[0083] (2) The synthesis of polymer P-ODDTO-TT is shown in the following reaction formula:

[0084]

[0085] An alkyl-substituted monomer compound (150 mg, 0.232 mmol, 1.0 eq.), 2,5-di(trimethyltin)-thieno[3,2-B]thiophene (108.07 mg, 0.232 mmol, 1.0 eq.), Pd2(dba)3 (4.67 mg, 0.0051 mmol, 0.0051 eq.), and tris(o-methylphenyl)phosphine (6.21 mg, 0.0204 mmol, 0.08 eq.) were weighed and placed in a 100 mL Schlenk flask, which was purged three times with argon. 5 mL of anhydrous chlorobenzene was added to the Schlenk flask, and the reaction mixture was reacted at 90 °C for 24 h under an argon atmosphere. After the reaction was completed, the reaction solution was cooled to room temperature, poured into 150 mL of methanol, filtered, and the solid material was collected. The solid material was washed with acetone, and then extracted with acetone, n-hexane, chloroform, and chlorobenzene, respectively. Finally, the polymer extracted from chloroform was concentrated and collected to obtain polymer P-ODDTO-TT (38 mg, yield 39.3%), and the polymer extracted from chlorobenzene was concentrated and collected to obtain polymer P-ODDTO-TT (56 mg, yield 57.9%).

[0086] Example 3

[0087] (1) Alkyl-substituted monomer compounds were obtained according to the method and conditions of Example 1.

[0088] (2) The synthesis of polymer P-ODDTO-T is shown in the following reaction formula:

[0089]

[0090] An alkyl-substituted monomer compound (150 mg, 0.232 mmol, 1.0 eq.), 2,5-bis(trimethyltinyl)thiophene (95.02 mg, 0.232 mmol, 1.0 eq.), Pd2(dba)3 (4.67 mg, 0.0051 mmol, 0.0051 eq.), and tris(o-methylphenyl)phosphine (6.21 mg, 0.0204 mmol, 0.08 eq.) were weighed and placed in a 100 mL Schlenk flask, which was purged three times with argon gas. 5 mL of anhydrous chlorobenzene was added to the Schlenk flask, and the reaction mixture was reacted at 90 °C for 24 h under an argon atmosphere. After the reaction was completed, the reaction solution was cooled to room temperature, poured into 150 mL of methanol, filtered, and the solid material was collected. The solid material was washed with acetone, and then extracted with acetone, n-hexane, and chloroform respectively. Finally, the polymer extracted from n-hexane was concentrated and collected to obtain polymer P-ODDTO-T (17 mg, yield 16.5%), and the polymer P-ODDTO-T extracted from chloroform was concentrated and collected (83 mg, yield 80.7%).

[0091] The molecular weight characterization data of polymers P-ODDTO-TT (Chloroform), P-ODDTO-TT (Chlorobenzene), and P-ODDTO-T extracted from chloroform are shown in Table 1.

[0092] Table 1. Molecular weight characterization data of different polymers

[0093] polymer <![CDATA[M w ]]> <![CDATA[M n ]]> PDI Polymer P-ODDTO-TT (Chloroform) 20859 8563 2.44 Polymer P-ODDTO-TT (Chlorobenzene) 15231 7395 2.06 Polymer P-ODDTO-T 30941 13690 2.26

[0094] The UV-Vis absorption spectra of polymers P-ODDTO-BT, P-ODDTO-TT, and P-ODDTO-T in chloroform are as follows: Figure 4 , Figure 5 and Figure 6 As shown.

[0095] Depend on Figures 4-6 It is known that the spectral absorption range of polymers P-ODDTO-BT, P-ODDTO-TT and P-ODDTO-T is 300-900 nm. The long-wavelength absorption peaks of the above three polymers correspond to intramolecular charge transfer, which is generated by the formation of DA push-pull electronic structure by the thiophene, bisthiophene and thiophene donor units and oxime acceptor units in the polymer.

[0096] In this invention, the organic thin-film transistor adopts a bottom-gate bottom-contact structure, specifically as follows: Figure 7 As shown.

[0097] The method for fabricating organic thin-film transistors using polymers P-ODDTO-TT (Chloroform), P-ODDTO-TT (Chlorobenzene), and P-ODDTO-T as active layers respectively includes the following steps:

[0098] (1) Prepare chloroform solutions of polymers P-ODDTO-TT (Chloroform), P-ODDTO-TT (Chlorobenzene) and P-ODDTO-T at a concentration of 5 mg / mL for later use.

[0099] (2) Use n-type silicon as the gate electrode.

[0100] (3) A 300 nm thick SiO2 thin film is prepared as an insulating layer on the upper surface of the gate electrode using a thermal generation method.

[0101] (4) Gold is deposited at both ends of the upper surface of the insulating layer using photolithography to form source and drain electrodes.

[0102] (The length of the channel between the source electrode and the drain electrode is 1000 μm and the width is 30 μm), and the substrate is obtained.

[0103] (6) The substrate is modified with n-octadecyl mercaptan, and then ultrasonically cleaned with deionized water, acetone and isopropanol respectively, and finally plasma cleaned to obtain the modified substrate.

[0104] (7) At room temperature, the modified substrate is immersed in a toluene solution of dodecyltrichlorosilane for 20 min for surface treatment. After the surface treatment is completed, it is cleaned with toluene and then dried under nitrogen flow to obtain the surface-treated substrate.

[0105] (8) Spin-coating the chloroform solution of the polymer onto the upper surface of the surface-treated substrate, specifically at a speed of 3000 rpm for 60 s. After spin-coating, the resulting device is placed on a heating plate and heated and annealed for 20 min in a nitrogen atmosphere at 25°C, 50°C, 100°C, 150°C and 200°C respectively, to form an active layer on the upper surface of the surface-treated substrate, thereby obtaining an organic thin-film transistor.

[0106] Table 2 Performance test results of organic thin-film transistors prepared from different polymers

[0107]

[0108]

[0109] Figure 8 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures.

[0110] Figure 9 The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures are shown.

[0111] Figure 10 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures.

[0112] Figure 11 The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-TT as the organic active semiconductor layer at different annealing temperatures are shown.

[0113] Figure 12 The graph shows the transfer characteristics of an organic field-effect transistor with polymer P-ODDTO-T as the organic active semiconductor layer at different annealing temperatures.

[0114] Figure 13The output characteristic curves of an organic field-effect transistor with polymer P-ODDTO-T as the organic active semiconductor layer are shown at different annealing temperatures.

[0115] From Table 2 and Figures 8-13 It can be seen that among the organic thin-film transistors prepared from polymers P-ODDTO-TT (Chloroform), P-ODDTO-TT (Chlorobenzene), and P-ODDTO-T, the organic thin-film transistor prepared from polymer P-ODDTO-T as the organic active semiconductor layer exhibits the best carrier transport performance after annealing at 250℃, with a mobility of 1.19 × 10⁻⁶. -2 cm 2 V -1 S -1 .

[0116] The above results demonstrate that the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one provided by this invention can serve as an effective building block for OTFTs, showing promising application prospects.

[0117] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Polymers based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one, namely polymer P-ODDTO-BT, polymer P-ODDTO-TT, and polymer P-ODDTO-T; wherein polymer P-ODDTO-BT, polymer P-ODDTO-TT, and polymer P-ODDTO-T respectively have the structures shown in Formula I, Formula II, and Formula III: In Equations I, II and III, 1 ≤ n ≤ 400 and n is an integer.

2. The method for preparing the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one according to claim 1, comprising the following steps: 2,6-Dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one and hydroxylamine hydrochloride were mixed and subjected to a condensation reaction to obtain an oxime derivative. The oxime derivatives were mixed with 1-bromo-2-octyldodecane and subjected to a substitution reaction to obtain alkyl-substituted monomeric compounds; The alkyl-substituted monomer compound was mixed with a bithiophene organotin reagent and subjected to a first polymerization reaction to obtain the polymer P-ODDTO-BT; the bithiophene organotin reagent was 5,5-bis(trimethyltinyl-2,2'-bithiophene). The alkyl-substituted monomer compound was mixed with a bis(trimethyltin)thiophene organotin reagent and subjected to a second polymerization reaction to obtain the polymer P-ODDTO-TT; the bis(trimethyltin)thiophene organotin reagent was 2,5-bis(trimethyltin)-thiophene[3,2-B]thiophene. The alkyl-substituted monomer compound was mixed with a thiophene organotin reagent and subjected to a third polymerization reaction to obtain the polymer P-ODDTO-T; the thiophene organotin reagent was 2,5-bis(trimethyltin)thiophene. The structural formulas of the oxime derivatives and alkyl-substituted monomer compounds are shown in Formula 1 and Formula 2, respectively:

3. The preparation method according to claim 2, characterized in that, The molar ratio of 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one to hydroxylamine hydrochloride is 1:

5.

4. The preparation method according to claim 2, characterized in that, The condensation reaction was carried out at a temperature of 80°C for 24 hours.

5. The preparation method according to claim 2, characterized in that, The molar ratio of the oxime derivative to 1-bromo-2-octyldodecane is 1:2.

5.

6. The preparation method according to claim 2, characterized in that, The substitution reaction was carried out at a temperature of 60°C for 8–15 hours.

7. The preparation method according to claim 2, characterized in that, The molar ratio of the alkyl-substituted monomer compound to the bis(thiophene) organotin reagent or the bis(thiophene) organotin reagent or the thiophene organotin reagent is 1:

1.

8. The preparation method according to claim 2, characterized in that, The temperature for the first polymerization reaction, the second polymerization reaction, and the third polymerization reaction was 90°C, and the time was 24 hours.

9. The application of the polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one as described in claim 1 in organic thin-film transistors.

10. An organic thin-film transistor, characterized in that, The active layer of the organic thin-film transistor is prepared using a polymer based on 2,6-dibromo-4H-cyclopentano[1,2-B:5,4-B]dithiophene-4-one as described in claim 1.

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