CN109776767B

CN109776767B - Conjugated polymer containing difluoronaphthothiophene diketone electron-withdrawing unit and synthetic method and application thereof

Info

Publication number: CN109776767B
Application number: CN201811647158.2A
Authority: CN
Inventors: 应磊; 李康; 黄飞; 曹镛
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2021-08-10
Anticipated expiration: 2038-12-29
Also published as: CN109776767A

Abstract

The invention discloses a conjugated polymer containing difluoronaphthothiophene diketone electron-withdrawing units, a synthetic method and application thereof, and belongs to the field of application of polymers to optoelectronic materials and devices. The conjugated polymer prepared by the invention adopts a benzo heterocyclic structure containing difluoride substitution, fluorine atoms and electron donor units form a non-bond effect, so that the transmission of current carriers in a planar and rigid main chain structure is enhanced, and high mobility is favorably obtained. The conjugated polymer has a wider optical band gap and is suitable for being matched with a small molecular receptor with a narrow band gap to realize the complementation of absorption spectra, so that the conjugated polymer can be used for manufacturing polymer light-emitting diode devices, polymer field effect transistors and active layers of polymer solar cells.

Description

Conjugated polymer containing difluoronaphthothiophene diketone electron-withdrawing unit and synthetic method and application thereof

Technical Field

The invention relates to the field of application of polymers in photoelectron materials and devices, in particular to a conjugated polymer containing difluoronaphthothiophene diketone electron-withdrawing units.

Background

With the development of human society, the reserves of traditional non-renewable energy sources such as coal, petroleum and natural gas are gradually reduced, and the search for new energy sources capable of sustainable development is not slow. Solar energy is used as a green renewable energy source, and is inexhaustible. As one of the important means for solving the energy problem, the organic solar cell has the advantages of easily available materials, light weight, flexibility, large-area preparation of thin-film devices and the like, and has received wide attention from scientists. The organic solar cell active layer material has a wide variety of types, is easy to modify in chemical structure, is simple and convenient to prepare and purify, and has remarkable advantages in material sources and cost. And the organic solar cell can be used for preparing roll-to-roll flexible thin film devices in a large area, so that the organic solar cell has a huge commercial application prospect. At present, although the variety of organic conjugated polymer materials is large, the number of materials with wide absorption and high carrier mobility is small, and in order to realize more efficient photoelectric conversion efficiency, the development of a novel high-performance donor polymer material has a very important meaning.

Disclosure of Invention

The invention aims to design and synthesize a conjugated polymer donor material containing a 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing unit with higher energy conversion efficiency aiming at the defects of the development of the current novel conjugated molecular material.

The invention also aims to provide a synthetic method and application of the conjugated polymer containing the 1, 3-di-R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing unit.

The invention is realized by the following technical scheme.

A conjugated polymer containing electron-withdrawing units of difluoronaphthothiophene diketone, namely a conjugated polymer containing 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing units, has a structural formula as follows:

wherein R is a hydrogen atom or an alkyl chain; ar1 and Ar2 are aromatic groups; d is an electron donor unit; the electron donor unit D is connected with 1, 3-di R-6, 7-difluoro-5, 8-Ar1, Ar2 naphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing units in a conjugated mode, n is the polymerization degree of the conjugated polymer, and n is a natural number of 1-10000.

Preferably, the alkyl chain is a linear, branched or cyclic alkyl chain with 1-24 carbon atoms, or one or more carbon atoms in the linear, branched or cyclic alkyl chain are substituted by an oxygen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, an ester group, a cyano group or a nitro group, and a hydrogen atom is substituted by a halogen atom, an oxygen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, an amino cation, an ester group, a cyano group or a nitro group.

Preferably, Ar1 or Ar2 comprises at least one of the following structures:

R₁is a hydrogen atom or an alkyl chain, or said alkylOne or more carbon atoms in the alkyl chain are substituted with oxygen atoms, alkenyl groups, alkynyl groups, aryl groups, hydroxyl groups, amino groups, carbonyl groups, carboxyl groups, nitro groups, phenyl groups or thienyl groups, or one or more hydrogen atoms in the alkyl chain are substituted with halogen atoms.

Preferably, the electron donor unit D comprises at least one of the following structures:

wherein R is₂、R₃Is a hydrogen atom or an alkyl chain, or one or more carbon atoms in the alkyl chain are substituted by an oxygen atom, a halogen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a phenyl group or a thienyl group, or one or more hydrogen atoms in the alkyl chain are substituted by a halogen atom.

Preferably, R₁、R₂、R₃Is a linear, branched or cyclic alkyl chain having 1 to 30 carbon atoms.

The invention also provides a synthesis method of the conjugated polymer containing the 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing unit, which comprises the following steps:

(1) synthesis of 1, 3-di R-6, 7-difluoro-5, 8-Ar₁,Ar₂Naphtho [2,3-c ]]Thiophene-4, 9-dione electron-withdrawing units.

(2) Under the protection of inert gas, dissolving an electron donor unit D, a 1, 3-di R-6, 7-difluoro-5, 8-Ar1, an Ar2 naphtho [2,3-c ] thiophene-4, 9-diketone unit and a catalyst palladium tetratriphenylphosphine in an organic solvent, sealing and heating, cooling to room temperature, precipitating a reaction solution in methanol, sequentially purifying with methanol, acetone, n-hexane, dichloromethane and chloroform, removing the catalyst, concentrating a chloroform component, precipitating in methanol again, and drying in vacuum to obtain the conjugated polymer containing the 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone.

Preferably, the molar ratio of the electron donor unit D, the 1, 3-di R-6, 7-difluoro-5, 8-Ar1, the Ar2 naphtho [2,3-c ] thiophene-4, 9-dione unit and the catalyst palladium tetrakistriphenylphosphine is 20: 20: 1.

preferably, the inert gas is nitrogen or argon; the specific conditions of the heating are microwave 80 ℃ for 2 minutes, 120 ℃ for 2 minutes, 160 ℃ for 2 minutes, and finally 200 ℃ for 45 minutes.

Preferably, the purification is a purification by a soxhlet extraction method.

The invention provides application of a conjugated polymer containing a 1, 3-di-R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing unit in preparing a light-emitting layer of a polymer light-emitting diode device, a semiconductor active layer in a polymer field effect transistor or an active layer of a polymer solar photovoltaic cell.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the electron-withdrawing unit containing 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone has weaker electron-withdrawing effect, and the polymer with wide band gap can be obtained by matching with the weaker electron-donating unit. And the unit contains a difluoro-substituted benzo heterocyclic structure, fluorine atoms and electron donor units form a non-bond effect, so that the transmission of current carriers in a planar and rigid main chain structure is enhanced, and high mobility is favorably obtained.

(2) The thiophene containing the 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing unit contains an alkyl side chain, which is beneficial to regulating the solubility of the copolymer. Due to good solution processing performance and excellent photoelectric performance, the preparation method has good application in the fields of manufacturing a luminescent layer of a polymer light-emitting diode, a polymer field effect transistor and an active layer of a polymer solar cell.

Drawings

FIG. 1 is a thermogravimetric plot of the polymer PFPT-BDT prepared in example 3;

FIG. 2 is a graph showing UV-VIS absorption spectra of the polymer PFPT-BDT prepared in example 3 in chlorobenzene solution and thin film;

FIG. 3 is a plot of cyclic voltammograms of electrochemical testing of the polymers PFPT-BDT and ferrocene prepared in example 3;

FIG. 4 is a plot of short-circuit current density versus voltage characteristics for organic solar cell devices based on the polymer PFPT-BDT prepared in example 3, PFPT-DTBDT prepared in example 4, PFPT-DT prepared in example 5, and PFPT-DFDT prepared in example 6;

Detailed Description

Specific embodiments of the present invention will be further described below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1

Preparation of 1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (thien-2-yl) naphtho [2,3-c ] thiophene-4, 9-dione:

(1) under nitrogen protection, 4, 5-difluorophthalic acid 1(4.04g,20mmol), one drop of N, N-Dimethylformamide (DMF), oxalyl chloride (10mL) and 20mL of anhydrous dichloromethane were added to a 100mL two-necked round-bottomed flask and stirred at room temperature for 12 hours. 2, 5-bis (2-ethylhexyl) thiophene 2(6.17g,20mmol), AlCl was added to the stirred solution₃(10.67g,80mmol), which was transferred to a 0 ℃ ice-water bath and stirred for 30 minutes, and then left to stir at room temperature for 3 hours. And (3) post-treatment: the reaction mixture was extracted with dilute aqueous hydrochloric acid and chloroform to obtain an organic phase, which was placed in a single vial while adding silica gel powder for rotary evaporation and then purified by column chromatography on silica gel (the eluent was selected from petroleum ether: dichloromethane of 4:1(v/v)) to obtain product 3(7.20g, yield: 75%) as a yellow solid.

(2) In a 250mL three-necked round-bottomed flask, diisopropylamine (3.04g,30mmol) was dissolved in anhydrous tetrahydrofuran (30mL) under nitrogen, the temperature was lowered to-78 deg.C, and n-butyllithium (12mL,2.5mol L) was slowly added dropwise thereto^-1Hexane solution), the reaction was kept stirred at-78 ℃ for 1 hour. Subsequently, product 3(3.42g,7.20mmol) was dissolved in chloroformTetrahydrofuran (25mL) was added to the reaction mixture and stirring was continued at-78 ℃ for 40 minutes. Finally, a solution of elemental iodine (7.62g,30mmol) in tetrahydrofuran (30mL) was added to the reaction mixture and the reaction was stirred overnight. And (3) post-treatment: pouring the reaction solution into saturated sodium bisulfite solution to remove unreacted iodine simple substance. Dichloromethane extraction and drying over anhydrous magnesium sulfate. After distillation under reduced pressure, the crude product was purified by a silica gel column (petroleum ether: dichloromethane: 3:1(v/v) was selected as an eluent), to give product 4(2.73g, yield: 60%) as a yellow solid.

(3) In a 50mL two-necked round-bottomed flask, the product 4(1.90g,3mmol), trimethylthiophene 5(3.36g,9mmol), bis-triphenylphosphine palladium dichloride (Pd (PPh) was added under nitrogen₃)Cl₂45mg, 2% mmol were dissolved in toluene (30mL) and heated to 90 deg.C under reflux for 48 hours. When the reaction of product 4 was complete, the heating was stopped and the temperature was lowered to room temperature. And (3) post-treatment: the reaction solution was poured into water, extracted with ethyl acetate, washed with saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate. After distillation under reduced pressure, the crude product was purified by a silica gel column (petroleum ether: dichloromethane: 8:1(v/v) was selected as an eluent), to give product 6(1.53g, yield: 80%) as a yellow solid.

Example 2

Preparation of 1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2,3-c ] thiophene-4, 9-dione (M1):

in a 100mL single-necked flask, compound 6(0.69g,1mmol) was dissolved in a mixed solvent of chloroform (30mL) and acetic acid (30mL) at a volume ratio of 1: 1. the vial was then placed in an ice bath, and when the temperature of the reaction solution was lowered to about 0 ℃, N-bromosuccinimide NBS (0.38g,2mmol) was added portionwise thereto, and the reaction was stirred at room temperature for 8 hours. And (3) post-treatment: the reaction solution was poured into water, extracted with dichloromethane, and the organic layer was washed with saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. After distillation under reduced pressure, the crude product was purified by a silica gel column (petroleum ether was selected as an eluent) to obtain M1(1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2,3-c ] thiophene-4, 9-dione) (0.68g, yield: 85%) as a yellow solid.

Example 3

Preparation of PFPT-BDT

In a water oxygen automatic control glove box, compound M1(1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2, 3-c)]Thiophene-4, 9-dione) (79.7mg, 0.10mmol), Compound M2(4, 8-bis (5- (2-ethylhexyl) thiophen-2-yl) benzo [1,2-b:4,5-b']Dithien-2, 6-diyl) bis (trimethyltin) (90.5mg, 0.10mmol) and the catalyst tetrakis triphenylphosphine palladium (5.86mg, 0.005mmol) were added to a 10mL microwave tube, dissolved by adding anhydrous xylene (2.5mL), and sealed with a silica gel cap. Placing a microwave tube in a microwave reactor, setting a temperature program: after the reaction was cooled to room temperature, the reaction solution was precipitated into 200mL of methanol, Soxhlet extraction was performed with methanol, acetone, n-hexane, dichloromethane and chloroform in this order, then an aqueous solution of sodium diethyldithiocarbamate trihydrate (225mg, 1mmol, 100mL of water) was added to the chloroform fraction, and the mixture was stirred at 60 ℃ for 8 hours to remove the palladium catalyst in the reaction, the chloroform fraction was concentrated, and precipitated again with methanol, and dried under vacuum to obtain a cyan solid PFPT-BDT (96mg, yield: 77.6%).¹H NMR、¹³C NMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 4

Preparation of PFPT-DTBDT

In a water oxygen automatic control glove box, compound M1(1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2, 3-c)]Thiophene-4, 9-dione) (79.7mg, 0.10mmol), Compound M3(4, 8-bis (5- (2-ethylhexyl) thiophen-2-yl) benzo [1,2-b:4,5-b']Dithiophene [3,2-b]Thiophene-2, 6-diyl) bis (trimethyltin) (90.5mg, 0.10mmol) and the catalyst tetrakis triphenylphosphine palladium (5.86mg, 0.005mmol) were added to a 10mL microwave tube, dissolved by adding anhydrous xylene (2.5mL), and sealed with a silica gel cap. Placing a microwave tube in a microwave reactor, setting a temperature program: continuing at 80 ℃ for 2 minutes, 120 ℃ for 2 minutes, 160 ℃ for 2 minutes, and finally 200 ℃ for 45 minutes, precipitating the reaction solution into 200mL of methanol after the reaction is cooled to room temperature, performing Soxhlet extraction with methanol, acetone, n-hexane, dichloromethane and chloroform in sequence, then adding an aqueous solution of sodium diethyldithiocarbamate trihydrate (225mg, 1mmol, 100mL of water) into the chloroform component, stirring at 60 ℃ for 8 hours, removing the palladium catalyst in the reaction, concentrating the chloroform component, precipitating with methanol again, and drying under vacuum to obtain a turquoise green solid PFPT-BDDTT (108mg, yield: 80.1%).¹H NMR、¹³C NMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 5

Preparation of PFPT-DT

In a water oxygen automatic control glove box, compound M1(1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2, 3-c)]Thiophene-4, 9-dione) (79.7mg, 0.10mmol), 5 '-bis (trimethyltin) -2,2' -dithiophene M4(49.1mg, 0.10mmol) and the catalyst palladium tetrakistriphenylphosphine (5.86mg, 0.005mmol) were added to a 10mL microwave tube, dissolved by adding anhydrous xylene (2.5mL), and sealed with a silica gel cap. Placing a microwave tube in a microwave reactor, setting a temperature program: 80 ℃ for 2 min, 120 ℃ for 2 min, 160 ℃ for 2 min, and finally 200 ℃ for 2 minAfter the reaction was cooled to room temperature for 45 minutes, the reaction solution was precipitated into 200mL of methanol, Soxhlet extraction was carried out with methanol, acetone, n-hexane, dichloromethane and chloroform in this order, then an aqueous solution of sodium diethyldithiocarbamate trihydrate (225mg, 1mmol, 100mL of water) was added to the chloroform fraction, stirring was carried out at 60 ℃ for 8 hours, the palladium catalyst in the reaction was removed, the chloroform fraction was concentrated, precipitation was carried out again with methanol, and vacuum drying was carried out to obtain PFPT-DT (62mg, yield: 74.2%) as a black solid.¹H NMR、¹³C NMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 6

Preparation of PFPT-DFDT

In a water oxygen automatic control glove box, compound M1(1, 3-bis (2-ethylhexyl) -6, 7-difluoro-5, 8-bis (5-bromothien-2-yl) naphtho [2, 3-c)]Thiophene-4, 9-dione) (79.7mg, 0.10mmol), Compound M5(3,3 '-difluoro- [2,2' -dithiophene)]-5,5' -diyl) -bis (trimethyltin) (52.8mg, 0.10mmol) and the catalyst tetrakis triphenylphosphine palladium (5.86mg, 0.005mmol) were added to a 10mL microwave tube, dissolved by addition of anhydrous xylene (2.5mL), and sealed with a silica gel cap. Placing a microwave tube in a microwave reactor, setting a temperature program: after the reaction was cooled to room temperature, the reaction mixture was precipitated into 200mL of methanol, followed by Soxhlet extraction with methanol, acetone, n-hexane, dichloromethane and chloroform, followed by addition of an aqueous solution of sodium diethyldithiocarbamate trihydrate (225mg, 1mmol, 100mL of water) to the chloroform fraction, stirring at 60 ℃ for 8 hours, removal of the palladium catalyst in the reaction, concentration of the chloroform fraction, precipitation again with methanol, and vacuum drying to obtain PFPT-DFDT (69mg, yield: 79.2%) as a black solid.¹H NMR、¹³C NMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

the thermogravimetric analysis (TGA) of the obtained polymer PFPT-BDT is carried out by using an instrument Netzsch TG 209, the heating rate is 20 ℃/min and the atmosphere is nitrogen, the thermogravimetric curve of the obtained polymer PFPT-BDT is shown in figure 1, and as can be seen from figure 1, the decomposition temperature of the polymer PFPT-BDT when the mass loss is 5 percent is 455 ℃, and the polymer PFPT-BDT shows good thermal stability.

An ultraviolet-visible light (UV-vis) absorption spectrum is Shimadzu UV-3600UV-vis-NIR spectrometer, absorption of the polymer PFPT-BDT in chlorobenzene solution and ultraviolet-visible light prepared into a thin film state are respectively measured, and an obtained ultraviolet-visible light absorption spectrum is shown in figure 2, as can be seen from figure 2, the absorption spectrum of the polymer PFPT-BDT has a three-peak characteristic, wherein an absorption peak corresponding to a short wavelength range (300 to 400nm) is local pi-pi transition, and two absorption peaks corresponding to a long wavelength range (500 to 700nm) are caused by an intramolecular charge transfer effect; note that the absorption spectrum of the film is red-shifted by about 10nm compared to the absorption spectrum of the solution, which is caused by the concentration in the film.

Using CHI630E electrochemical workstation, and taking saturated calomel electrode, platinum wire electrode and glassy carbon electrode as reference electrode, auxiliary electrode and working electrode, respectively, and tetrabutyl ammonium hexafluorophosphate (Bu)₄NPF₆) Acetonitrile solvent (0.1mol L)^-1) For the working liquid, the scanning rate was set to 100mV s^-1And measuring the cyclic voltammetry characteristics of the polymer PFPT-BDT in a film state. The Cyclic Voltammetry (CV) test results in cyclic voltammetry curves of the polymers PFPT-BDT and ferrocene as shown in FIG. 3, and as can be seen from FIG. 3, the oxidation potential and the reduction potential of the polymer PFPT-BDT are respectively 0.91eV and-1.27 eV, while the corresponding potential of ferrocene is 0.38eV, and the molecular orbital level of the polymer PFPT-BDT is calculated according to the following formula: highest occupied molecular orbital energy level (E)_HOMO) -e (4.80-0.38 + 0.91-5.33 (electron volts, eV); lowest unoccupied molecular orbital level (E)_LUMO) -e (4.80-0.38-1.27) ═ 3.15 (electron volts, eV).

Example 7

Preparation of organic solar cells based on conjugated polymers prepared in examples 3 to 6

The polymer solar photovoltaic cell adopts a positive mounting structure ITO/PEDOT, PSS/Activelayer/PFN-Br/Ag. The ITO glass substrate is used as a cavity collecting electrode, the ITO glass is sequentially subjected to ultrasonic washing by using acetone, a detergent, deionized water and isopropanol, and then the ITO glass is placed into an oven to be dried overnight at 70 ℃; after carrying out plasma surface treatment on the dried ITO substrate for 4 minutes, spin-coating PEDOT (PSS) with the thickness of 40 nanometers, annealing at 150 ℃ for 20 minutes, and transferring the ITO substrate into a glove box filled with nitrogen; the polymer and the ITIC (structural formula is shown below) are mixed and dissolved in Chlorobenzene (CB) (the mass ratio of the polymer to the ITIC is 1:1, the concentration of the polymer is 12mg/mL, the mixture is stirred for 6 hours at 70 ℃ until the polymer is completely dissolved, the mixture is coated on PEDOT: PSS in a spinning mode to be used as an optical active layer with the thickness of 100 nanometers, then the active layer is annealed for 10 minutes at 100 ℃, after the annealing, a layer of PFN-Br (structural formula is shown below) with the thickness of 5 nanometers is coated on the active layer in a spinning mode to be used as a cathode interface, and finally, the mixture is evaporated in a vacuum evaporation bin (2.0 multiplied by 10) to be used as a cathode interface^-6mbar), a layer of silver with the thickness of 100 nanometers is evaporated on the active layer through a mask plate to be used as a cathode, and the effective area of the device is 0.04cm²。

The properties of solar photovoltaic cell devices based on the conjugated polymers prepared in examples 3-6 are shown in table 1.

TABLE 1 Properties of solar photovoltaic cell devices based on conjugated polymers prepared in examples 3-6

As can be seen from Table 1, the conjugated polymers prepared in examples 3-6 all showed good device performance, and the devices prepared from the polymer PFPT-BDT showed high open-circuit voltage (0.85V) and short-circuit current density (13.98 mA/cm)²) And fill factor (60.0)8%), the energy conversion efficiency reaches 7.14%; the device prepared from the polymer PFPT-DTBDT has the same open-circuit voltage as PFPT-BDT and higher short-circuit current density (14.50 mA/cm)²) And fill factor (64.40%), the energy conversion efficiency has a maximum of 7.94%, due to the better planarity, better molecular stacking of DTBDT cells than BDT cells. PFPT-DFDT produces devices that exhibit reduced open circuit voltages compared to PFPT-DT due to fluorine atoms lowering their HOMO level values.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention and are intended to be equivalent substitutions are included in the scope of the present invention.

Claims

1. A conjugated polymer containing 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing units is characterized in that the structural formula is as follows:

wherein R is a hydrogen atom or an alkyl chain; ar1 and Ar2 are aromatic groups; d is an electron donor unit; the electron donor unit D is connected with 1, 3-di R-6, 7-difluoro-5, 8-Ar1, Ar2 naphtho [2,3-c ] thiophene-4, 9-diketone electron-withdrawing units in a conjugated mode; and n is a natural number of 1-10000, and is the polymerization degree of the conjugated polymer.

2. The 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing unit-containing conjugated polymer of claim 1, wherein Ar1 or Ar2 comprises at least one of the following structural formulae:

in the formula, R₁Is a hydrogen atom or an alkyl chain, or one or more carbon atoms in the alkyl chain are substituted by an oxygen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a phenyl group or a thienyl group, or one or more hydrogen atoms in the alkyl chain are substituted by a halogen atom.

3. The 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing unit-containing conjugated polymer of claim 1, wherein the electron donor unit D comprises at least one of the following structural formulae:

in the formula, R₂、R₃Is a hydrogen atom or an alkyl chain, or one or more carbon atoms in the alkyl chain are substituted by an oxygen atom, a halogen atom, an alkenyl group, an alkynyl group, an aryl group, a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a phenyl group or a thienyl group, or one or more hydrogen atoms in the alkyl chain are substituted by a halogen atom.

4. The 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] -containing compound according to claim 2 or 3]Conjugated polymers of electron-withdrawing units of thiophene-4, 9-diones, characterized in that R is₁、R₂、R₃Is a linear, branched or cyclic alkyl chain having 1 to 30 carbon atoms.

5. A method for synthesizing the conjugated polymer containing 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing units as claimed in any one of claims 1 to 4, comprising the steps of:

(1) synthesis of 1, 3-di R-6, 7-difluoro-5, 8-Ar₁,Ar₂Naphtho [2,3-c ]]Thiophene-4, 9-dione electron-withdrawing units;

(2) under the protection of inert gas, dissolving an electron donor unit D, a 1, 3-di R-6, 7-difluoro-5, 8-Ar1 unit, an Ar2 naphtho [2,3-c ] thiophene-4, 9-diketone unit and a catalyst tetrakis (triphenylphosphine) palladium in an organic solvent, sealing and heating, cooling to room temperature, precipitating the reaction solution in methanol, sequentially purifying with methanol, acetone, n-hexane, dichloromethane and chloroform, removing the catalyst, concentrating chloroform components, precipitating in methanol again, and drying in vacuum to obtain the conjugated polymer containing the 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-diketone.

6. The method for synthesizing the conjugated polymer containing the 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing unit according to claim 5, wherein the molar ratio of the electron donor unit D, the 1, 3-di R-6, 7-difluoro-5, 8-Ar1, the Ar2 naphtho [2,3-c ] thiophene-4, 9-dione unit and the catalyst tetrakis (triphenylphosphine) palladium is 20: 20: 1.

7. the method for synthesizing the conjugated polymer containing 1, 3-di R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing units according to claim 5, wherein the inert gas is nitrogen or argon; the specific conditions of the heating are microwave 80 ℃ for 2 minutes, 120 ℃ for 2 minutes, 160 ℃ for 2 minutes, and finally 200 ℃ for 45 minutes.

8. The method for synthesizing the conjugated polymer containing 1, 3-di-R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing units according to claim 5, wherein the purification is a purification by a Soxhlet extraction method.

9. Use of a conjugated polymer comprising 1, 3-di-R-6, 7-difluoronaphtho [2,3-c ] thiophene-4, 9-dione electron-withdrawing units according to claim 1 in the preparation of a light-emitting layer of a polymer light-emitting diode device, in the preparation of a semiconductor active layer in a polymer field effect transistor, or in the preparation of an active layer of a polymer solar photovoltaic cell.