CN112321806B

CN112321806B - Conjugated polymer containing thieno [3,4-b ] pyrazine and preparation method and application thereof

Info

Publication number: CN112321806B
Application number: CN202011297961.5A
Authority: CN
Inventors: 陆燕; 何泽旺; 韩冬; 韩洪停
Original assignee: Tianjin University of Technology
Current assignee: Tianjin University of Technology
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2023-05-02
Anticipated expiration: 2040-11-19
Also published as: CN112321806A

Abstract

The invention provides a conjugated polymer containing thieno [3,4-b ] pyrazine and a preparation method and application thereof, wherein the preparation method is as follows: the thieno [3,4-B ] pyrazine derivative monomer A, the aromatic dibromo monomer B, the transition metal catalyst, the solvent, the ligand, the alkali and the additive are uniformly mixed, and the reaction time is 12-72 hours at 90-120 ℃ in a certain atmosphere. After the reaction is finished, cooling to room temperature and purifying to obtain the conjugated polymer containing thieno [3,4-b ] pyrazine. Compared with the preparation technologies of Stille coupling, suzuki coupling and the like which are commonly used for preparing the polymer, the invention obviously shortens the synthesis steps, avoids preparing an organic metal reagent or a borate intermediate, does not need to carry out end capping treatment on the polymer, has low cost, and the prepared polymer has good performance in the application of an organic light-emitting diode (OLED).

Description

Conjugated polymer containing thieno [3,4-b ] pyrazine and preparation method and application thereof

Technical Field

The invention belongs to the technical field of conjugated polymers, and particularly relates to a conjugated polymer of thieno [3,4-b ] pyrazine, and a preparation method and application thereof.

Background

Conjugated polymers containing thieno [3,4-b ] pyrazine structural units have wide application in photoelectric materials. At present, the polymer is mainly prepared by a Suzuki, stille coupling polymerization method. Both polymerization processes require pre-functionalization of the comonomer to produce its corresponding halide and metallic tin compound or borate derivative. The monomer synthesis reaction has the advantages of more steps, high cost and harsh synthesis conditions, and the prepared metal stannide has poor stability and is not easy to store. In addition, when the prepared polymer is used as an active material for an optoelectronic device, the polymer often needs to be subjected to end-capping treatment to ensure the device performance.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a conjugated polymer containing thieno [3,4-b ] pyrazine units, and a preparation method and application thereof. Compared with Suzuki, stille coupling polymerization method, the method has the advantages of fewer synthesis steps, avoidance of pre-synthesis of the organic metal compound or the borate intermediate, no need of end capping and low cost.

The technical proposal of the invention

A preparation method of a conjugated polymer containing thieno [3,4-b ] pyrazine comprises the following steps:

1) The thieno [3,4-B ] pyrazine derivative monomer A, the aromatic dibromo monomer B, the transition metal catalyst, the solvent, the ligand, the alkaline substance and the additive are uniformly mixed at room temperature, and then are stirred and reacted for 12-72 hours under the condition of heating to 90-120 ℃ in a proper gas atmosphere. After the reaction was completed, the mixture was cooled to room temperature.

2) And dripping the obtained reaction liquid into a proper amount of methanol for sedimentation, and carrying out suction filtration to obtain a crude product.

3) Sequentially performing Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing a remover by rotary evaporation, and then performing vacuum drying to obtain a pure product, namely the thieno [3,4-b ] pyrazine conjugated polymer.

The structural general formula of the monomer A is as follows:

wherein R is ₁ H, C of a shape of H, C ₁ -C ₂₀ Alkyl, phenyl or substituted phenyl.

The structural general formula of the monomer B is as follows:

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the method specifically comprises the following structural formula:

wherein R is ₂ 、R ₃ 、R ₄ 、R ₅ 、R ₆ 、R ₇ 、R ₈ Are all H, C ₁ -C ₂₀ Alkyl, C ₁ -C ₂₀ Alkyl substituents or halogen. And X is carbon, nitrogen or silicon.

The C is ₁ -C ₂₀ The substituents in the alkyl substituent may be selected from the following groups: cycloalkyl, aryl, heteroaryl, heteroalicyclic, hydroxy, alkoxy, aryloxy, mercapto, alkylthio, arylthio, halo, carbonyl, thiocarbonyl, O-carbamoyl, N-carbamoyl, O-thiocarbamoyl, N-thiocarbamoyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxyl, O-carboxyl, thiocyanato, nitro, trihalomethanesulfonyl or silyl.

The transition metal catalyst is trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate and Pd (dppf) Cl ₂ 、Pd(OAc) ₂ 、PdCl ₂ 、Pd ₂ (dba) ₃ 、Pd(TFA) ₂ 、PdCl ₂ (PPh ₃ ) ₂ 、Pd(OH) ₂ 、Pd(PPh ₃ ) ₄ And one of Pd/C.

The solvent is one of tetrahydrofuran, toluene, N-dimethylformamide, N-dimethylacetamide and dimethyl sulfoxide.

The ligand is P (o-PhOMe) ₃ 、P(o-PhNMe ₂ ) ₃ 、PCy ₃ -HBF ₄ 、P ^t Bu ₃ -HBF ₄ 、PPh ₃ And P ^t Bu ₂ Me-HBF ₄ One of them.

The alkaline substance is Cs ₂ CO ₃ 、K ₂ CO ₃ 、Na ₂ CO ₃ 、NaHCO ₃ One of NaOAc, KOAc, csOAc and KF.

The additive is one of pivalic acid, neoheptanoic acid, neodecanoic acid, adamantanoic acid and acetic acid.

The gas atmosphere is air, nitrogen, argon or other inert gases.

In the technical scheme, the ratio of the monomer A to the monomer B to the transition metal catalyst to the ligand to the alkaline substance to the additive is 1:1 (0.01-0.05) (0-0.1) (0-3) (0-2) in parts by weight of the substances.

The concentration of the monomers A and B in the solvent is 0.01 to 2mol/L, preferably 0.1 to 0.5mol/L.

The invention also provides the conjugated polymer containing thieno [3,4-b ] pyrazine obtained by the preparation method; and the use of the conjugated polymer as an active material in an Organic Light Emitting Diode (OLED).

The invention has the advantages and beneficial effects that:

compared with the prior art, the method has the advantages of fewer synthesis steps, avoidance of synthesis of the organic metal compound or the borate intermediate, no end capping and low cost, and is specifically expressed in the following steps:

1. compared with the existing Stille and Suzuki coupling polymerization preparation technology, the invention shortens the synthesis steps and reduces the cost by adopting direct arylation coupling polymerization;

2. the polymerization method avoids the use of reagents sensitive to air (such as tertiary butyl lithium and the like) and toxic metal reagents, and does not generate toxic byproducts. The resulting polymers can be used directly as active materials for optoelectronic devices, such as OLEDs, without termination.

Drawings

FIG. 1 is an optical absorption spectrum of a thienopyrazine-9, 9-dioctylfluorene copolymer P1 obtained in example 1.

FIG. 2 is an electrochemical cyclic voltammogram of the thienopyrazine-9, 9-dioctylfluorene copolymer P1 obtained in example 1.

Detailed Description

The invention will be described in further detail with reference to specific embodiments and drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

The general procedure for the reaction is as follows:

adding the monomer A, the monomer B, the transition metal catalyst, the solvent, the ligand, the alkali and the additive into a reaction container, and reacting for 12-72 hours in a certain atmosphere at the temperature of 90-120 ℃ in the reaction system to obtain a polymer crude product.

General method of polymer purification: and (3) purifying the crude polymer product by adopting Soxhlet extraction. The method comprises the following specific steps: after the reaction, cooling to room temperature, concentrating the reaction liquid, dropwise adding the reaction liquid into 100mL of methanol for sedimentation, and carrying out suction filtration to obtain a crude product. And (3) sequentially performing Soxhlet extraction on the crude product with methanol and n-hexane for 24 hours respectively, performing Soxhlet extraction with chloroform until chloroform in a Soxhlet extraction tube is colorless, collecting chloroform extract, performing rotary evaporation to remove solvent, and performing vacuum drying to obtain a polymer pure product.

The purchase sources for the drugs involved in the following examples are as follows:

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the types of instruments involved in the following examples are as follows:

example 1:

the first step: synthesis of Compound 1

3, 4-Diaminothiophene dihydrochloride (2.67 mmol), 2, 3-butanedione (2.67 mmol), potassium acetate (5.34 mmol), ethanol (15 mL) and dichloromethane (5 mL) were added to a 100mL round bottom flaskReflux reaction was carried out at 50℃for 6 hours. The reaction was stopped, the reaction mixture was extracted with dichloromethane and taken up in Na ₂ SO ₄ After drying, purification by silica gel chromatography, eluting with ethyl acetate/dichloromethane (1/9, v/v) afforded compound 1 as tan (0.28 g, 65% yield). ¹ H NMR(400MHz,CDCl ₃ )δ:7.81(s,2H),2.64(s,6H)。

And a second step of: synthesis of Polymer P1

9, 9-dioctyl-2, 7-dibromofluorene (0.3048 mmol), compound 1 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.012 mmol), tris (o-methoxyphenyl) phosphine (0.024 mmol), cesium carbonate (0.6096 mmol) and pivalic acid (0.09 mmol) were added to a reaction flask, 1mL of toluene was added, and heated at 110℃for 48 hours. The reaction was cooled to room temperature and settled in methanol. And (3) carrying out suction filtration to obtain a crude product, sequentially carrying out Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and then carrying out vacuum drying to obtain a pure product, thus obtaining the 2, 3-dimethylthienopyrazine-9, 9-dioctylfluorene copolymer P1. (141.4 mg, yield 84.1%, M) _n ＝20kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:7.77–8.26(m,br,6H),2.66(s,6H),2.08(br,4H),1.07(br,24H),0.71(br,6H).

Example 2

Synthesis of Polymer P2

2, 7-dibromo-9- (1-octylnonyl) -9H-carbazole (0.3048 mmol), compound 1 (0.3048 mmol), palladium acetate (0.012 mmol), tricyclohexylphosphine fluoroborate (0.024 mmol), potassium carbonate (0.9144 mmol) and pivalic acid (0.18 mmol) were added to a reaction flask, 1mL of tetrahydrofuran was added, and heating was performed at 110℃for 48 hours. The reaction was cooled to room temperature and settled in methanol. And (3) carrying out suction filtration to obtain a crude product, sequentially carrying out Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and then carrying out vacuum drying to obtain a pure product, thus obtaining the 2, 3-dimethylthienopyrazine-9- (1-octyl nonyl) -9H-carbazole copolymer P2. (91.7 mg, product)Rate 53.2%, M _n ＝53kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:7.81–8.92(m,br,6H),4.72(s,1H),2.69(s,6H),2.50(br,2H),2.04(br,2H),1.07(br,24H),0.70(br,6H).

Example 3

Synthesis of Polymer P3

3, 7-dibromo-9, 9-dioctyl-9H-9-silafluorene (0.3048 mmol), compound 1 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.015 mmol), tris (o-methoxyphenyl) phosphine (0.030 mmol), cesium carbonate (0.6096 mmol) were added to a reaction flask, 1mL toluene was added, and heated at 110℃for 48 hours. The reaction was cooled to room temperature and settled in methanol. And (3) carrying out suction filtration to obtain a crude product, sequentially carrying out Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and then carrying out vacuum drying to obtain a pure product, thus obtaining the 2, 3-dimethylthienopyrazine-9, 9-dioctyl-9H-9-silafluorene copolymer P3. (110.1 mg, 63.7% yield, M) _n ＝12kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:8.35(br,6H),2.63(s,6H),1.18(br,28H),0.76(br,6H).

Example 4

Synthesis of Polymer P4

4, 7-dibromo-5, 6-difluoro-2- (2-hexyldecyl) -2H-benzo [ d ]][1,2,3]Triazole (0.3048 mmol), compound 1 (0.3048 mmol), palladium acetate (0.006 mmol), tris (o-methoxyphenyl) phosphine (0.012 mmol), potassium carbonate (0.9144 mmol) and pivalic acid (0.18 mmol) were added to a reaction flask, 1mL of toluene was added, and heated at 110℃for 48 hours. The reaction was cooled to room temperature and settled in methanol. Filtering to obtain crude product, sequentially extracting with methanol, n-hexane and chloroform, collecting chloroform extractive solution, rotary evaporating to remove solvent, and vacuum drying to obtain pure product2, 3-Dimethylthiophene-pyrazine-5, 6-difluoro-2- (2-hexyldecyl) -2H-benzo [ d ]][1,2,3]Triazole copolymer P4. (46.3 mg, yield 28.1%, M) _n ＝2.2kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:4.63(s,2H),2.76(s,2H),1.26(br,25H),0.86(br,6H).

Example 5

Synthesis of Polymer P5

5, 12-dibromo-2, 9-bis (2-octyldodecyl) anthraco [2,1,9-def:6,5,10-d ' e ' f ] ']Diisoquinoline-1,3,8,10 (2H, 9H) -tetraone (0.3048 mmol), compound 1 (0.3048 mmol), palladium acetate (0.012 mmol), tricyclohexylphosphine fluoroborate (0.024 mmol), potassium carbonate (0.9144 mmol) and pivalic acid (0.18 mmol) were added to a reaction flask, 1mL of tetrahydrofuran was added, and the mixture was heated at 90℃for 24 hours. The reaction was cooled to room temperature and settled in methanol. Extracting with methanol, n-hexane and chloroform sequentially, collecting chloroform extract, rotary evaporating to remove solvent, and vacuum drying to obtain pure product, namely 2, 3-dimethyl thienopyrazine-2, 9-di (2-octyl dodecyl) anthracene [2,1,9-def:6,5,10-d ' e ' f ] ']Diisoquinoline-1,3,8,10 (2H, 9H) -tetraketone copolymer P5. (22 mg, yield 6.4%, M) _n ＝1.9kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:8.64(d,2H),8.59(d,2H),8.21(d,2H),4.08(d,4H),2.65(s,6H),1.97(s,2H),1.18(br,64H),0.77(br,12H).

Example 6

The first step: synthesis of Compound 2

3, 4-diaminothiophene dihydrochloride (1.06 mmol), dibenzoyl (1.06 mmol), potassium acetate (2.13 mmol), ethanol (25 mL) were added to a 100mL round bottom flask and reacted at 80℃under reflux for 24 h. The reaction was stopped, the reaction mixture was extracted with dichloromethane and taken up in Na ₂ SO ₄ After drying, the siliconPurification by gum chromatography eluting with methylene chloride afforded compound 2 as yellow brown (0.14 g, 48% yield). ¹ H NMR(400MHz,CDCl ₃ )δ:7.99(s,2H),7.37(m,4H)，7.25(m,6H)。

And a second step of: synthesis of Polymer P6

1, 4-dibromo-2, 5-bis ((2-ethylhexyl) oxy) benzene (0.3048 mmol), compound 2 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.003 mmol), tris (o-methoxyphenyl) phosphine (0.006 mmol), cesium carbonate (0.6096 mmol) and pivalic acid (0.09 mmol) were added to a reaction flask, 1mL of toluene was added, and heated at 120℃for 36 hours. The reaction was cooled to room temperature and settled in methanol. And (3) carrying out suction filtration to obtain a crude product, sequentially carrying out Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and then carrying out vacuum drying to obtain a pure product, thus obtaining the 2, 3-diphenyl thienopyrazine-1, 4-dibromo-2, 5-bis ((2-ethylhexyl) oxy) benzene copolymer P6. (42 mg, 22.2% yield, M) _n ＝3.3kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:7.95(br,4H),7.59(s,2H),7.32(br,4H),7.10(br,2H),4.09(s,4H),1.93(s,2H),1.19(br,16H)，0.81(br,12H).

Example 7

Synthesis of Polymer P7:

2, 6-dibromo-4, 8-bis [ (2-octyldodecyloxy) oxy]Benzo [1,2-b:4,5-b ]']Dithiophene (0.3048 mmol), compound 2 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.015 mmol), tris (o-methoxyphenyl) phosphine (0.03 mmol), cesium carbonate (0.6096 mmol) and pivalic acid (0.09 mmol) were added to a reaction flask, 1mL toluene was added and heated at 110℃for 48 hours. The reaction was cooled to room temperature and settled in methanol. Extracting with methanol, n-hexane and chloroform sequentially, collecting chloroform extractive solution, evaporating to remove solvent, and vacuum drying to obtain pure product, namely 2, 3-diphenyl thienopyrazine-1, 4-dibromo-2, 5-bis ((2-ethylhexyl) oxy)Benzene copolymer P7. (45 mg, 13.8% yield, M) _n ＝3.3kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:8.21(br,4H),7.60(br,2H),7.33(br,6H),4.31(s,4H),2.00(s,2H),1.26(br,64H),0.85(br,12H).

Example 8

The first step: synthesis of Compound 3

3, 4-diaminothiophene dihydrochloride (2.67 mmol), 7, 8-tetradecyldione (2.67 mmol), potassium acetate (5.34 mmol), ethanol (15 mL) and dichloromethane (5 mL) were added to a 100mL round bottom flask and reacted at 50℃under reflux for 6 hours. The reaction was stopped, the reaction mixture was extracted with dichloromethane and taken up in Na ₂ SO ₄ After drying, purification by silica gel chromatography, eluting with ethyl acetate/dichloromethane (1/9, v/v) afforded compound 3 as tan (0.33 g, 40% yield). ¹ H NMR(400MHz,CDCl ₃ )δ:7.81(s,2H),2.89(t,4H),1.79(p,4H),1.47(p,4H),1.35(m,8H),0.89(t,6H)。

And a second step of: synthesis of Polymer P8

2, 6-dibromo-N-octyl-dithioeno [3,2-b:2,3-d]Pyrrole (0.3048 mmol), compound 3 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.012 mmol), tris (o-methoxyphenyl) phosphine (0.024 mmol), cesium carbonate (0.6096 mmol) and pivalic acid (0.09 mmol) were added to a reaction flask, 1mL toluene was added and heated at 100deg.C for 72 hours. The reaction was cooled to room temperature and settled in methanol. And (5) carrying out suction filtration to obtain a crude product. Sequentially performing Soxhlet extraction on the crude product with methanol, N-hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and vacuum drying to obtain pure product, namely 2, 3-dihexylthiophene pyrazine-N-octyl-dithiophene [3,2-b:2,3-d]Pyrrole copolymer P8. (18 mg, yield 9.9%, M) _n ＝1.8kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:7.15(s,1H),6.88(s,1H),4.12(br,2H),2.80(br,4H),1.83(s,2H),1.33(br,26H),0.81(br,9H).

Example 9

2, 6-dibromo-4, 4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b:3,4-b ]']Dithiophene (0.3048 mmol), compound 3 (0.3048 mmol), trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate (0.012 mmol), tris (o-methoxyphenyl) phosphine (0.024 mmol), cesium carbonate (0.762 mmol) and pivalic acid (0.18 mmol) were added to a reaction flask, 1mL of toluene was added, and heated at 110℃for 24 hours. The reaction was cooled to room temperature and settled in methanol. Extracting with methanol, n-hexane and chloroform sequentially, collecting chloroform extract, evaporating to remove solvent, and vacuum drying to obtain pure product, namely 2, 3-dihexylthiophene-pyrazine-4, 4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b:3,4-b ]']Dithiophene copolymer P9. (30 mg, yield 14.0%, M) _n ＝2.7kDa)。 ¹ H NMR(400MHz,CDCl ₃ )δ:7.45(br,2H),2.95(br,4H),2.0(br,8H),1.35(br,12H),0.98(br,18H),0.67(br,18H).

Example 10

It is another object of the present invention to provide a representation of the optoelectronic properties of the conjugated polymer containing thieno [3,4-b ] pyrazine obtained by the above preparation method.

As the polymer P1 synthesized in the above example 1, P1 was mixed with various organic solvents including chlorinated solvents such as chloroform, chlorobenzene, dichlorobenzene, etc., and other solvents including methanol, toluene, tetrahydrofuran, etc. The polymer was found to have good solubility in chlorinated solvents and a film was prepared by spin coating a chloroform solution of the polymer onto a glass plate. And detecting the properties of the polymer such as spectrum, and the optical band gap empirical formula of the polymer is Eopt g=1240/lambda, wherein E _g As the optical band gap of the polymer, λ is the initial value of the absorption spectrum in the long wavelength direction) fig. 1 is an optical spectrum.

The maximum absorption value of the polymer P1 in the solution is 554nm, the maximum absorption value of the polymer after spin coating into a film is 567nm, and the optical band gap of the polymer P1 is 1.78eV according to the formula Eoptg=1240/lambda from the initial absorption position of the polymer.

Example 11

The electrochemical band gap of the polymer was measured using electrochemical cyclic voltammetry. The polymer synthesized in example 1 was dissolved in chloroform, and then the solution was added dropwise to a working electrode such as a platinum sheet, using a 0.1mol/L anhydrous acetonitrile solution of tetrabutylammonium hexafluorophosphate as an electrolyte solution; and a three-electrode system with a glassy carbon electrode as a working electrode, a saturated calomel electrode as a reference electrode and glass filaments as auxiliary electrodes. Ferrocene/ferrocenium is an internal standard to measure the electrochemical properties of polymers. The HOMO and LUMO energy levels of the polymers were calculated according to equation one:

HOMO＝-e(Eoxonset+4.8)(eV)

LUMO＝-e(Eredonset+4.8)(eV)

wherein E is ^ox And E is ^red The oxidation and reduction potentials of the polymer P1 are calculated by the above formula, the corresponding HOMO level of the polymer is-5.48 eV, the corresponding LUMO level is-3.67 eV, the electrochemical band gap is 1.81eV, and the electrochemical cyclic voltammogram of the polymer P1 is shown in FIG. 2.

Example 12:

the electroluminescent device structure is ITO/PEDOT, PSS/emitting layer/LiF/Al. The sample was ultrasonically cleaned with detergent, deionized water, acetone and methanol, respectively. After 15 minutes of Ultraviolet (UV) -ozone treatment, a 70 nm thick poly (ethylenedioxythiophene): poly (styrenesulfonate) PEDOT-PSS film was spin-coated on the ITO substrate and dried at 200℃for 10 minutes. The hole transport layer film is prepared by spin-coating PTAA (poly [ bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine) from O-DCB (1, 2-dichlorobenzene) solution]) A uniform 20nm thick film on top of the PEDOT-PSS layer was formed and annealed at 180℃for 20 minutes. The emissive polymer film was spin coated from a solution of N, N-dimethylformamide to form a uniform 60nm thick film and dried at 150℃for 20 minutes. The whole process of thermal evaporation is 2×10 ^-5 The vacuum deposition is carried out under Pa, a LiF layer of 1nm is deposited under vacuum, and an aluminum cathode of 110nm is deposited under vacuum.

Optimal conditions for the fabrication and characterization of polymeric electroluminescent devices based on the polymer of example 1 and the method of operation of example 12An External Quantum Efficiency (EQE) of 0.37% in a film state and a Luminance (Luminance) of 1300cd/m ² 。

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that any simple variations, modifications or other equivalent which would be able to persons skilled in the art without departing from the core of the invention fall within the scope of the invention.

Claims

1. A method for preparing a conjugated polymer containing thieno [3,4-b ] pyrazine, which is characterized by comprising the following steps:

uniformly mixing a thieno [3,4-B ] pyrazine derivative monomer A, an aromatic dibromo monomer B, a transition metal catalyst, a solvent, a ligand, an alkaline substance and an additive at room temperature, heating to 90-120 ℃ in a gas atmosphere, stirring and reacting for 12-72 hours, and cooling to room temperature after the reaction is finished, wherein the additive is one of pivalic acid, neoheptanoic acid, neodecanoic acid, adamantanoic acid and acetic acid; dripping the obtained reaction liquid into methanol for sedimentation, and carrying out suction filtration to obtain a crude product; sequentially performing Soxhlet extraction on the crude product by using methanol, normal hexane and chloroform, collecting chloroform extract, removing solvent by rotary evaporation, and vacuum drying to obtain a pure product, namely the conjugated polymer containing thieno [3,4-b ] pyrazine;

the structural general formula of the monomer A is as follows:

wherein R is ₁ Is H, C ₁ -C ₂₀ Alkyl, phenyl;

the structure of the monomer B is as follows:

wherein R is ₂ 、R ₃ 、R ₄ 、R ₅ 、R ₆ 、R ₇ 、R ₈ All are H, C ₁ -C ₂₀ Alkyl, C ₁ -C ₂₀ Alkyl substituents or halogen; x is carbon, nitrogen or silicon;

wherein said C ₁ -C ₂₀ The substituents in the alkyl substituents are selected from the following groups: cycloalkyl, aryl, heteroaryl, heteroalicyclic, hydroxy, alkoxy, aryloxy, mercapto, alkylthio, arylthio, halo, carbonyl, thiocarbonyl, O-carbamoyl, N-carbamoyl, O-thiocarbamoyl, N-thiocarbamoyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxyl, O-carboxyl, thiocyanato, nitro, trihalomethanesulfonyl or silyl.

2. The preparation method according to claim 1, wherein the transition metal catalyst is trans-bis [2- (di-o-tolylphosphine) benzyl dipalladium acetate, pd (dppf) Cl ₂ 、Pd(OAc) ₂ 、PdCl ₂ 、Pd ₂ (dba) ₃ 、Pd(TFA) ₂ 、PdCl ₂ (PPh ₃ ) ₂ 、Pd(OH) ₂ 、Pd(PPh ₃ ) ₄ And one of Pd/C.

3. The method according to claim 1, wherein the solvent is one of tetrahydrofuran, toluene, N-dimethylformamide, N-dimethylacetamide and dimethylsulfoxide.

4. The method of claim 1, wherein the ligand is P (o-PhOMe) ₃ 、P(o-PhNMe ₂ ) ₃ 、PCy ₃ -HBF ₄ 、P ^t Bu ₃ -HBF ₄ 、PPh ₃ And P ^t Bu ₂ Me-HBF ₄ One of them.

5. The method according to claim 1, wherein the alkaline substance is Cs ₂ CO ₃ 、K ₂ CO ₃ 、Na ₂ CO ₃ 、NaHCO ₃ One of NaOAc, KOAc, csOAc and KF.

6. The method of claim 1, wherein the gas atmosphere is air, nitrogen, argon or other inert gas.

7. The preparation method according to claim 1, wherein the ratio of the monomer A to the monomer B to the transition metal catalyst to the ligand to the alkaline substance to the additive is 1:1 (0.01-0.05): (0-0.1): (0-3): (0-2) in parts by weight of the substances.

8. The process according to claim 1, wherein the concentration of the monomers A and B in the solvent is 0.01 to 2mol/L.

9. The process according to claim 8, wherein the concentration of the monomer A and the monomer B in the solvent is 0.1 to 0.5mol/L.

10. Conjugated polymer containing thieno [3,4-b ] pyrazine obtainable by the process according to any of claims 1 to 9.

11. Use of a conjugated polymer comprising thieno [3,4-b ] pyrazine as claimed in claim 10 as active material in organic light emitting diodes.