CN106928435B

CN106928435B - Copolymer luminescent material containing fluoro side group and preparation method and application thereof

Info

Publication number: CN106928435B
Application number: CN201710176431.7A
Authority: CN
Inventors: 应磊; 王小君; 郭婷; 彭俊彪; 曹镛
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2017-03-23
Filing date: 2017-03-23
Publication date: 2020-09-22
Anticipated expiration: 2037-03-23
Also published as: CN106928435A

Abstract

The invention discloses a copolymer luminescent material containing fluoro side groups, and a preparation method and application thereof. The fluorine-containing side group-containing copolymer luminescent material has higher fluorescence quantum yield due to larger conjugation length, better planarity and good interfacial property, and is beneficial to improving the device efficiency of the material; meanwhile, the synthetic method of the fluorine-containing side group-containing copolymer luminescent material is simple, the material has good solubility, film forming property and film form stability, and the luminescent layer based on the material does not need annealing treatment when preparing an organic luminescent device, so that the preparation process is simpler.

Description

Copolymer luminescent material containing fluoro side group and preparation method and application thereof

Technical Field

The invention belongs to the technical field of organic photoelectric materials, and particularly relates to a fluoro side group-containing copolymer luminescent material, and a preparation method and application thereof.

Background

Organic light emitting diodes (O/PLED) have been produced as a new generation of flat panel display technology, and compared with conventional cathode ray diodes, the organic light emitting diodes (O/PLED) have the advantages of light weight, high-efficiency light emission, energy saving, environmental protection, flexible display, low processing cost and the like, and have wide application prospects. Although organic/high-light-distribution diodes have made a breakthrough in organic flat panel displays and white light illumination, the degree of industrialization is far lower than expected, and many key problems remain to be solved in the field of research. The optimization of luminescent materials, colorization technology, paper film technology, high-resolution display technology, active drive technology, packaging technology and other aspects still have important basic problems which are not clear, so that the overall performance, the manufacturing cost and the like become bottleneck problems which restrict the wide application of the luminescent materials. With the deep research of polymer electroluminescent materials and devices by various academic institutions and large companies in the world, it is believed that the problems can be gradually solved, and the application of organic/polymer light-emitting diodes in the aspects of display and illumination has wide market prospects. Among them, development of novel, efficient and stable materials becomes a key.

The polymer has good solubility, is suitable for solution processing, has good fluorescence quantum yield, and has high efficiency and stability, and the luminescent device is bluer saturated blue light, so that the requirements of full-color display can be met. Therefore, the organic light-emitting diode has great development potential and prospect in the field of organic electronic display.

Disclosure of Invention

The invention aims to solve the problems of the prior polymer light-emitting diode (PLED) and provide a copolymer luminescent material containing fluoro side group units. The copolymer luminescent material has good solubility and good interface performance, is suitable for solution processing and ink-jet printing, and has good development prospect.

In the copolymer luminescent material, the excited state molecules taking the fluorine-containing side group-containing units as the copolymer directly transfer radiation transition to the ground state molecules through dipole-dipole effect between the excited state molecules and the narrow band gap ground state molecules, so that the ground state molecules are excited to emit light, the carrier transmission balance of the luminescent polymer is realized, the luminescent efficiency of the device is improved, and the polymer has higher fluorescence quantum yield.

The invention also aims to provide a preparation method of the copolymer luminescent material containing the fluoro side group.

The invention also aims to provide application of the copolymer luminescent material containing the fluoro side group in a luminescent layer of a light-emitting diode.

The invention is realized by the following technical scheme.

A fluoro side group-containing copolymer luminescent material has the following chemical structural formula:

wherein x and y are mole fractions, x is more than 0 and less than or equal to 0.4, y is more than 0 and less than or equal to 0.4, and x + y is less than or equal to 0.5; n is the degree of polymerization, 20< n < 500; ar1 and Ar2 are both functional groups; r is H, a straight chain or branched chain alkyl group with 1-20 carbon atoms, or an alkoxy group with 1-20 carbon atoms.

Further, the functional group Ar1 is any one of the following structural formulas:

wherein R is₁H, a linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms.

Further, the functional group Ar2 is any one of the following structural formulas:

wherein R is₂Is a linear chain or branched chain alkyl group containing fluorine or fluorobenzene with 1-20 carbon atoms.

The preparation method of the conjugated polymer luminescent material containing the fluoro side group mainly comprises the preparation of a fluoro side group unit and the synthesis of the conjugated polymer containing the fluoro side group.

The preparation method of the copolymer luminescent material containing the fluoro side group comprises the following steps:

(1) adding bromide with an Ar1 structure, bromide with an Ar2 structure, 3, 7-dibromo-S, S-dibenzothiophene dioxide, tricyclohexyl phosphine and palladium acetate into a three-neck bottle, and exhausting gas;

(2) under the protection of argon, adding benzotrifluoride and an organic alkali solution for dissolving, and heating and refluxing; sequentially adding phenylboronic acid and bromobenzene for end-capping reaction;

(3) cooling to room temperature after the end-capping reaction is finished, pouring the reaction liquid into methanol for precipitation, filtering, and performing alumina column chromatography by using toluene as an eluent;

(4) and after the chromatography is finished, pouring the concentrated washing liquid into methanol for precipitation, filtering and drying to obtain the copolymer luminescent material containing the fluoro side group.

In the step (1), the mole ratio of the bromide with the Ar1 structure, the bromide with the Ar2 structure and the 3, 7-dibromo-S, S-dibenzothiophene dioxide is 0.5: 0.45-0.1: 0.05-0.4.

Further, in the step (1), the molar ratio of the bromide with the structure of Ar1 to the tricyclohexyl phosphine is 0.5: 0.02.

further, in the step (1), the mole ratio of the bromide of the Ar1 structure to the palladium acetate is 0.5: 0.02.

further, in the step (2), the organic alkali is tetraethylammonium hydroxide, the concentration of the organic alkali solution is 1.5M, and the volume ratio of the addition amount of the organic alkali solution to the addition amount of the benzotrifluoride is 1: 5.

Further, in the step (2), the heating reflux temperature is 80-100 ℃, and the time is 24-48 h.

Further, in the step (2), the temperature for adding the phenylboronic acid and the bromobenzene to carry out the end-capping reaction is 80-100 ℃ and the time is 6-12 hours.

Further, in the step (2), the molar ratio of the added amount of the phenylboronic acid to the bromide with the Ar1 structure is 0.1: 0.5.

further, in the step (2), the molar ratio of the bromobenzene to the bromide with the structure of Ar1 is 0.2: 0.5.

Further, the bromide of the Ar1 structure is replaced by boron ester of Ar1 structure; the bromide of the Ar2 structure is replaced by boron ester of Ar2 structure.

The copolymer luminescent material containing the fluoro side group is applied to a luminescent layer of a light-emitting diode, the copolymer luminescent material containing the fluoro side group is dissolved by an organic solvent, and then a film is formed by a spin coating, ink-jet printing or printing method to obtain the luminescent layer of the light-emitting diode.

Further, the organic solvent includes xylene, chlorobenzene, chloroform, and the like.

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

(1) the fluorine-containing side group-containing copolymer luminescent material has higher fluorescence quantum yield due to larger conjugation length, better planarity and good interfacial property, and is beneficial to improving the device efficiency of the material;

(2) the invention has simple synthesis method, better solubility, film forming property and film form stability, and the luminescent layer based on the material does not need annealing treatment when preparing the organic luminescent device, thus leading the preparation process to be simpler.

Drawings

FIG. 1 is a drawing of compound M1¹H NMR spectrum;

FIG. 2 is a drawing of compound M1¹³C NMR spectrum;

FIG. 3 is a drawing of compound M1¹⁸F NMR spectrum;

FIG. 4 is a graph of the current density-voltage-luminance of polymers PFSO1, PFSO 2;

figure 5 is a plot of lumen efficiency versus current density for electroluminescent devices based on polymers PFSO1, PFSO 2;

FIG. 6 is a graph showing the electroluminescence spectra of polymers PFSO1 and PFSO2 in the thin film state;

detailed description of the invention

For a better understanding of the present invention, the following examples are given to illustrate the present invention, but the scope of the present invention is not limited thereto.

Example 1

Preparation of PFSO 1:

(1) under nitrogen atmosphere, 2, 7-dibromo- (9, 9-diphenylhydroxy) fluorene2g，3.94mol)，C₈H₈F₉I(3.96g，9.84mmol)，K₂CO₃(2.18g, 15.74mmol) and 100ml of N' N-dimethylacetamide were put in a 250ml two-necked flask, heated to 80 ℃ and reacted for 12 hours, and then the mixture was returned to room temperature, 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, the eluent was a mixed solvent of dichloromethane and petroleum ether (volume ratio: 1:5), and ethanol was recrystallized to obtain a white solid of compound M1 in 80% yield.¹H NMR、¹³CNMR、¹⁸The F NMR spectra are shown in FIG. 1, FIG. 2 and FIG. 3, respectively, and the target product is analyzed. The chemical reaction equation is as follows:

(2) under argon atmosphere, M1(49.32mg, 46.69. mu. mol), M2(27.94mg, 46.69. mu. mol), M3(76.82mg, 140.06. mu. mol) and M4(150.00mg, 233.44. mu. mol) were charged into a 50ml two-necked flask, 8ml of benzotrifluoride was added for complete dissolution, air was purged three times, palladium acetate (2.10mg, 9.34. mu. mol) and tricyclohexylphosphine (5.24mg, 18.68. mu. mol) were rapidly added, air was purged three times, then 2ml of tetraethylammonium hydroxide was added, the temperature was raised to 80 ℃ and the reaction was carried out for 24 hours. Then adding 30mg of phenylboronic acid for end capping, after 12 hours, capping with 0.3ml of bromobenzene, and continuing to react for 12 hours; and (3) dropwise adding the product into methanol to precipitate, stirring, filtering, dissolving the crude product into 20mL of toluene, taking 200-300-mesh silica gel as a stationary phase, taking toluene as an eluent to perform column chromatography, concentrating the solvent under reduced pressure, precipitating in methanol again, stirring, filtering, and drying in vacuum to obtain a polymer solid. And finally, sequentially extracting the mixture by using methanol, acetone and tetrahydrofuran for 24 hours respectively to remove small molecules. Dripping the concentrated tetrahydrofuran solution into methanol for precipitation, and vacuum drying to obtain flocculent solid. The yield was 82%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 2

Preparation of PFSO 2:

under argon atmosphere, M1(49.32mg, 46.69. mu. mol), M5(17.46mg, 46.69. mu. mol), M3(76.82mg, 140.06. mu. mol) and M4(150.00mg, 233.44. mu. mol) were charged into a 50ml two-necked flask, 8ml of benzotrifluoride was added for complete dissolution, air was purged three times, palladium acetate (2.10mg, 9.34. mu. mol) and tricyclohexylphosphine (5.24mg, 18.68. mu. mol) were rapidly added, air was purged three times, then 2ml of tetraethylammonium hydroxide was added, the temperature was raised to 80 ℃ and the reaction was carried out for 24 hours. Then adding 30mg of phenylboronic acid for end capping, after 12 hours, capping with 0.3ml of bromobenzene, and continuing to react for 12 hours; and (3) dropwise adding the product into methanol to precipitate, stirring, filtering, dissolving the crude product into 30mL of toluene, performing column chromatography by using 200-300-mesh silica gel as a stationary phase and toluene as an eluent, concentrating the solvent under reduced pressure, precipitating in methanol again, stirring, filtering, and drying in vacuum to obtain a polymer solid. And finally, sequentially extracting the mixture by using methanol, acetone and tetrahydrofuran for 24 hours respectively to remove small molecules. Dripping the concentrated tetrahydrofuran solution into methanol for precipitation, and vacuum drying to obtain flocculent solid. The yield was 75%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 3

Preparation of PFSO 3:

(1) under a nitrogen atmosphere, 2, 7-dibromofluorene (2.00g, 6.17mmol), C₈H₈F₉I (6.2g, 15.43mmol), sodium hydroxide (24g, 1.04mol), tetrabutylammonium bromide (200mg, 0.62mmol) and 100ml toluene were added to a 250ml two-necked flask, heated to 180 ℃ to react for 12 hours, returned to room temperature, 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 is purified by a silica gel column, and the eluent is twoMethyl chloride and petroleum ether mixed solvent (volume ratio of 1:5), methanol recrystallization, and white solid obtained as compound M6 with yield of 67%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

(2) under argon atmosphere, M6(40.73mg, 46.69. mu. mol), M5(17.46mg, 46.69. mu. mol), M3(76.82mg, 140.06. mu. mol) and M4(150.00mg, 233.44. mu. mol) were charged into a 50ml two-necked flask, 8ml of benzotrifluoride was added for complete dissolution, air was purged three times, palladium acetate (2.10mg, 9.34. mu. mol) and tricyclohexylphosphine (5.24mg, 18.68. mu. mol) were rapidly added, air was purged three times, then 2ml of tetraethylammonium hydroxide was added, the temperature was raised to 80 ℃ and the reaction was carried out for 24 hours. Then adding 30mg of phenylboronic acid for end capping, after 12 hours, capping with 0.3ml of bromobenzene, and continuing to react for 12 hours; and (3) dropwise adding the product into methanol to precipitate, stirring, filtering, dissolving the crude product into 20mL of toluene, taking 200-300-mesh silica gel as a stationary phase, taking toluene as an eluent to perform column chromatography, concentrating the solvent under reduced pressure, precipitating in methanol again, stirring, filtering, and drying in vacuum to obtain a polymer solid. And finally, sequentially extracting the mixture by using methanol, acetone and tetrahydrofuran for 24 hours respectively to remove small molecules. Dripping the concentrated tetrahydrofuran solution into methanol for precipitation, and vacuum drying to obtain flocculent solid. The yield was 75%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 4

Preparation of PFSO 4:

(1) adding fluorene (1g, 6.02mmol) and 40mL of anhydrous tetrahydrofuran into a 250mL three-necked flask, cooling to-78 ℃, dropwise adding n-butyllithium (1.54g, 24.06mmol), and reacting for 30 minutes; returning to room temperature, reacting for 1 hour, and thenSub-cooling to-78 deg.C, and dissolving C₁₀H₄F₁₇I (17.27g, 30.08mol) was added dropwise to the reaction mixture, and after stirring for 10 minutes, the mixture was reacted at room temperature for 4 hours. The reaction solution was suspended to dryness to obtain a crude product, which was extracted with ethyl acetate, and the organic layer was washed with brine, dried over anhydrous magnesium sulfate, and purified by silica gel column chromatography (eluent selected from petroleum ether) to obtain a white solid a with a yield of 43%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

(2) adding compound A (2g, 1.89mmol), iron powder (11mg, 0.196mmol) and 50mL of trichloromethane into a 250mL three-necked bottle, and cooling in an ice-water bath; 5mL of a bromine (634.14m g, 3.97 mol)/chloroform mixed solution is added dropwise, and the temperature in the bottle does not exceed 5 ℃ when the solution is added dropwise. After the reaction was completed, filtration and recrystallization from chloroform gave M7 as a white solid in 83% yield.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

(3) under argon atmosphere, M7(100.00mg, 82.22. mu. mol), M5(20.50mg, 54.81. mu. mol), M8(130.89mg, 137.04. mu. mol) were charged into a 50ml two-necked flask, 8ml of benzotrifluoride was added for complete dissolution, air was purged three times, palladium acetate (1.23mg, 5.48. mu. mol) and tricyclohexylphosphine (3.07mg, 10.96. mu. mol) were rapidly added thereto, air was purged three times, 2ml of tetraethylammonium hydroxide was then added, and the temperature was raised to 80 ℃ to react for 24 hours. Then adding 30mg of phenylboronic acid for end capping, after 12 hours, capping with 0.3ml of bromobenzene, and continuing to react for 12 hours; dropping the product into methanol for precipitation, stirring, filtering, dissolving the crude product into 30mL of toluene, taking 200-300 mesh silica gel as a stationary phase, taking toluene as an eluent for column chromatography, concentrating the solvent under reduced pressure, and precipitating in methanol againStirring, filtering and vacuum drying to obtain solid polymer. And finally, sequentially extracting the mixture by using methanol, acetone and tetrahydrofuran for 24 hours respectively to remove small molecules. Dripping the concentrated tetrahydrofuran solution into methanol for precipitation, and vacuum drying to obtain flocculent solid. The yield was 60%.¹H NMR、¹³CNMR、¹⁸FNMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 5

Preparation of PFSO 5:

under argon atmosphere, M9(72.78mg, 46.69. mu. mol), M2(27.94mg, 46.69. mu. mol), M3(76.82mg, 140.06. mu. mol) and M4(150.00mg, 233.44. mu. mol) were charged into a 50ml two-necked flask, 8ml of benzotrifluoride was added for complete dissolution, air was purged three times, palladium acetate (1.23mg, 5.48. mu. mol) and tricyclohexylphosphine (3.07mg, 10.96. mu. mol) were rapidly added, air was purged three times, then 2ml of tetraethylammonium hydroxide was added, the temperature was raised to 80 ℃ and the reaction was carried out for 24 hours. Then adding 30mg of phenylboronic acid for end capping, after 12 hours, capping with 0.3ml of bromobenzene, and continuing to react for 12 hours; and (3) dropwise adding the product into methanol to precipitate, stirring, filtering, dissolving the crude product into 30mL of toluene, performing column chromatography by using 200-300-mesh silica gel as a stationary phase and toluene as an eluent, concentrating the solvent under reduced pressure, precipitating in methanol again, stirring, filtering, and drying in vacuum to obtain a polymer solid. And finally, sequentially extracting the mixture by using methanol, acetone and tetrahydrofuran for 24 hours respectively to remove small molecules. Dripping the concentrated tetrahydrofuran solution into methanol for precipitation, and vacuum drying to obtain flocculent solid. The yield was 74%.¹H NMR、¹³CNMR、¹⁸F NMR analysis shows that the target product is obtained. The chemical reaction equation is as follows:

example 6

Preparation of electroluminescent device:

on a prepared Indium Tin Oxide (ITO) glass, the square resistance of the ITO glass is 10-20 omega/□, acetone, a detergent, deionized water and isopropanol are sequentially used for ultrasonic cleaning, and plasma treatment is carried out for 10 minutes. A film of polyethoxythiophene (PEDOT: PSS ═ 1:1 by mass) doped with polystyrenesulphonic acid was spin-coated onto ITO to a thickness of 150nm, and the PEDOT: PSS film was dried in a vacuum oven at 80 ℃ for 8 hours. Then, a dimethylbenzene solution (1 wt%) of the copolymer containing the fluoro side group is spin-coated on the surface of a PEDOT (PSS) film, wherein the thickness of the PEDOT is 80nm, and the PEDOT is used as a light-emitting layer; and finally, a thin CsF (1.5nm) layer and a 120nm thick metal Al layer are sequentially evaporated on the luminescent layer.

Fig. 4 is a graph of current density-voltage-luminance of the prepared polymers PFSO1 and PFSO2, and it can be seen from fig. 4 that both the luminance and the current density of PFSO2 are higher than those of PFSO 1.

FIG. 5 is a graph of lumen efficiency versus current density for electroluminescent devices based on the polymers PFSO1, PFSO2, from FIG. 5 it can be seen that PFSO1 reaches 1.83mA/cm at current density²When the lumen efficiency reaches the maximum value of 1.9cd/A, the PFSO2 reaches 0.29mA/cm at the current density²When the lumen efficiency reaches the maximum value of 2.8cd/A, PFSO2 has better efficiency than PFSO 1.

FIG. 6 is an electroluminescence spectrum of the prepared polymers PFSO1 and PFSO2 in a thin film state, wherein the maximum emission peak of PFSO1 is 425nm, and the maximum emission peak of PFSO2 is 447 nm.

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 fluoro side group-containing copolymer luminescent material is characterized by having the following chemical structural formula:

wherein x and y are mole fractions, x is more than 0 and less than or equal to 0.4, y is more than 0 and less than or equal to 0.4, and x + y is less than or equal to 0.5; n is the degree of polymerization, 20< n < 500; ar1 and Ar2 are both functional groups; r is H, a straight chain or branched chain alkyl group with 1-20 carbon atoms, or an alkoxy group with 1-20 carbon atoms; the functional group Ar1 is any one of the following structural formulas:

wherein R is₁H, a straight chain or branched chain alkyl group with 1-20 carbon atoms, or an alkoxy group with 1-20 carbon atoms; the functional group Ar2 is any one of the following structural formulas:

2. The application of the fluoro side group-containing copolymer luminescent material in a luminescent layer of a light-emitting diode according to claim 1, wherein the fluoro side group-containing copolymer luminescent material is dissolved by an organic solvent and then formed into a film by a spin coating or printing method to obtain the luminescent layer of the light-emitting diode; the organic solvent comprises xylene, chlorobenzene or chloroform.