CN101392173A - Method for preparing copolymer luminescent material by electrochemical polymerization - Google Patents

Abstract

The invention discloses a method for preparing a copolymer luminescent material through electrochemical polymerization. Two types of monomers are adopted in the preparation method. Congjugate homopolymers obtained by the respective homopolymerization of the two types of monomers contain different energy gaps. The two types of monomers, an electrolysis solvent and supporting electrolyte are added into a three-electrode cell to form an electrolyte. A potentiostatic method is adopted for carrying out polymerization and a copolymer solution is obtained, or a copolymer film is obtained by sediment on a working electrode, and then the copolymer luminescent material is obtained through aftertreatment. The preparation method of the copolymer luminescent material can effectively regulate the emitting color of the copolymer luminescent material, is simple, practical, low in cost, and is easy for industrialized production.

Description

Method for preparing copolymer luminescent material by electrochemical polymerization

(1) Technical field

The invention relates to a preparation method of a copolymer luminescent material.

(2) Background technology

The luminescence of polymers is a phenomenon of radiative transition of molecules from the excited state back to the ground state. When a polymer molecule absorbs energy, its electrons jump from a lower energy level to a higher energy level, becoming an electronically excited state molecule. The molecule in the excited state is unstable, and when it returns to the ground state through the process of radiative transition decay, it will be accompanied by the emission of photons, showing the phenomenon of luminescence.

In 1990, the Burroughes group of the University of Cambridge published the electroluminescent properties of poly-p-phenylene vinylene (PPV), which opened up a new field of light-emitting device research—polymer thin film electroluminescent devices (PLEDs) (J.H.Burroughes, D.D.C.Bradley, A.R. Brown, R.N. Marks, K. Mackay, R.H. Friend, P.L. Burns, A.B. Holmes, Light-emitting diodes based on conjugated polymers, Nature 1990, 347: 539-541). In the past ten years, great achievements have been made in polymer electroluminescence. There have been great breakthroughs in terms of device efficiency, brightness and service life, and even reached a practical level, especially in blue and green. , red three-color polymer luminescent material research is more encouraging.

There are many kinds of light-emitting polymers, mainly including polyphenylene vinylenes, polyphenylenes, polyfluorenes, polythiophenes and polycarbazoles. Since each polymer has fixed luminous properties, single luminous color, and low luminous efficiency, it is very necessary to modify the luminescent polymer. There are three main methods of modification at present: substituent modification, doping modification and copolymerization modification. Substituent modification not only improves the solubility of the conjugated polymer material, making it easy to process, but also can adjust the emission wavelength and increase the luminous efficiency. Doping modification mainly uses various dopants to change the luminescent color of the polymer. Copolymerization is a general method for preparing new polymer light-emitting materials. It can not only realize full-color display, but also can complement the advantages of various substances, greatly improving the luminous efficiency and prolonging the luminous lifetime. It has become the main way to develop polymer luminescent materials at present.

Copolymerization modification is currently mainly used in chemical catalytic copolymerization and chemical oxidation copolymerization. The former requires the use of expensive catalysts (NiCl ₂ (dppp), PdCl ₂ (PPh ₃ ) ₂ , Pd(PPh ₃ ) ₄ , etc.) and monomers (arylboronic acid, etc.) under harsh experimental conditions (anhydrous and oxygen-free) , the cost is relatively high, which undoubtedly greatly increases the cost and limits large-scale production; and the latter generally needs to design and synthesize suitable monomers first, and then carry out polymerization. The monomer design of the first step is itself a relatively complicated research topic, and the second step of polymerization is required, which is relatively cumbersome.

(3) Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of a copolymer luminescent material that can effectively adjust the luminescent color of the copolymer luminescent material, is simple and practical, has low cost, and is easy for industrial production.

In order to solve the above technical problems, the preparation method of the copolymer luminescent material according to the present invention adopts the following technical scheme: the copolymer luminescent material is prepared by copolymerizing two monomers by electrochemical polymerization, and the two monomers The conjugated homopolymers obtained by the homopolymerization of the respective monomers have different energy gaps; the electrochemical polymerization method is as follows: the electrolytic solvent, two monomers, and the supporting electrolyte are added to a three-electrode electrolytic cell to form an electrolyte, and a constant potential Polymerized by the method to obtain a copolymer solution or electrodeposited on the working electrode to obtain a copolymer film, and after post-treatment to obtain the copolymer luminescent material; the initial concentrations of the two monomers in the electrolyte are each 10 ^-4 ~10mol/L.

In the electrochemical polymerization method described in the present invention, in the selection of monomers, commonly used monomers in the preparation of copolymerized luminescent materials in this field can be used, because the conjugated homopolymer obtained by the homopolymerization of the two monomers selected With different energy gaps, using such two kinds of conjugated monomers for electrochemical copolymerization can obtain copolymers with different energy gaps from the conjugated homopolymers obtained by the above two homopolymerizations, and realize the photoreaction of light-emitting polymers. modified. Generally speaking, the difference in energy gap of the conjugated homopolymer obtained by the homopolymerization of the two monomers can be in the range of 0.02eV to 2eV.

Further, among the two conjugated monomers, one of the conjugated monomers is preferably selected from one of the following: 9,9'-dialkylfluorene, N-alkylcarbazole, and the other conjugated monomer is preferably selected from One of the following: thiophene, alkylthiophene.

In the present invention, since the luminescent color of the product is related to the ratio of the two monomers, those skilled in the art can determine the feeding ratio according to the performance requirements, such as 100:1-1:100. The initial concentrations of the two conjugated monomers in the electrolyte are preferably 10 ⁻³ to 10 ⁻² mol/L, that is, the ratio of the two is preferably 10:1 to 1:10.

Generally speaking, the supporting electrolyte can be composed of anion and cation in a ratio of 1:1, and the anion is preferably a mixture of one or more of the following: perchlorate ion, tetrafluoroborate ion, hexafluorophosphoric acid root ion, hexafluoroarsenate ion; the cation is preferably a mixture of one or more of the following: lithium ion, tetramethylammonium ion, tetraethylammonium ion, tetrabutylammonium ion, tetra-n-propylammonium ions, tetra-n-hexylammonium ions. The concentration of the supporting electrolyte in the electrolyte solution of the present invention is recommended to be 10 ^-3 to 10 ^-1 mol/L, more preferably 10 ^-2 mol/L.

The electrolytic solvent is preferably one of the following: fluorosulfonic acid, acetonitrile, toluene, ethanol, methanol, chloroform, dichloromethane, tetrahydrofuran, cyclohexane, propylene carbonate, phenylacetonitrile, ether, petroleum ether.

More specifically, boron trifluoride ether can be used as both an electrolytic solvent and a supporting electrolyte, so when boron trifluoride ether is added to the three-electrode electrolytic cell, no additional supporting electrolyte is needed.

In the three-electrode electrolytic cell described in the present invention, working electrode is gold, platinum, lead, titanium, graphite, glassy carbon or ITO electrode; Auxiliary electrode is gold, platinum, lead, titanium, graphite electrode or ITO electrode; Reference electrode It is silver-silver ion electrode, silver-silver chloride electrode or saturated calomel electrode.

When using the constant potential method for polymerization, it is recommended to follow the following steps: apply a constant potential signal to the working electrode, the range of the constant potential signal is 0.8 ~ 2.0V, and the time is 200s ~ 48h.

When the copolymer film is obtained by electrochemical polymerization, the post-treatment can adopt the following method: the copolymer film deposited on the working electrode is cleaned, filtered, and dried to obtain the final product, and the solvent used for cleaning is preferably one of the following: : N,N-dimethylacetamide, N,N-dimethylformamide, acetonitrile, toluene, ethanol, methanol, chloroform, dichloromethane, tetrahydrofuran, cyclohexane, Pyridine, propylene carbonate, phenylacetonitrile, ether, acetic acid, formic acid, petroleum ether.

When the copolymer solution is obtained by electrochemical polymerization, the post-treatment can adopt the following method: add a precipitation solvent to the obtained copolymer solution to precipitate the copolymer, filter, wash, and dry to obtain the final product; the precipitation solvent is selected From methanol, ethanol, acetone, acetonitrile, formic acid or acetic acid.

The copolymer light-emitting material described in the present invention can be applied in the light-emitting layer of PLED.

The electrochemical copolymerization method described in the present invention is used to prepare copolymer luminescent materials. Compared with the prior art, the present invention has the following advantages: the present invention utilizes an electrochemical method and adopts two kinds of conjugated homopolymers with incapable properties. The copolymerization modification of the luminescent polymer has been successfully realized, and the electrochemical method is applicable to a wide range of monomers. By adjusting the type or ratio of the two monomers, the luminescent color of the copolymer luminescent material can be effectively adjusted. ; and the electrochemical polymerization method is simple and practical, with low cost and easy industrial production.

(4) Specific implementation methods

The technical solutions of the present invention will be further described below with specific examples, but the protection scope of the present invention is not limited thereto.

Example 1

Electrochemical Copolymerization of 9,9'-Dihexylfluorene and Thiophene

Dissolve 9,9'-dihexylfluorene (0.01 mol/L) and thiophene (0.1 mol/L) in acetonitrile, and add 10 ^-2 mol/L tetrabutylammonium perchlorate as electrolyte. Add it to a three-electrode electrolytic cell, in which the working electrode is ITO glass; the counter electrode is platinum sheet; the reference electrode is silver-silver chloride electrode. Polymerization was carried out by a constant potential method, and the polymerization potential was 1.3V. Polymerization time 2h. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Example 2

Electrochemical Copolymerization of 9,9'-Dioctylfluorene and 3,4-Didecylthiophene

Dissolve 9,9′-dioctylfluorene (0.1mol/L) and 3,4-didecylthiophene (0.01mol/L) in acetonitrile, and add tetrabutylammonium perchlorate 10 ^-2 mol/ L, as an electrolyte. Add it to a three-electrode electrolytic cell, in which the working electrode is ITO glass; the counter electrode is platinum sheet; the reference electrode is silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.1V. Polymerization time 1h seconds. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Example 3

Electrochemical Copolymerization of N-Butylcarbazole and 3-Butylthiophene

Dissolve N-butylcarbazole (0.1mol/L) and 3-butylthiophene (0.1mol/L) in boron trifluoride ether, join in the three-electrode electrolytic cell, wherein working electrode is ITO glass; The electrode is a platinum sheet; the reference electrode is a silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.1V. Polymerization time 48h. After the polymerization is completed, the polymer in the electrolytic cell is precipitated with methanol, filtered, washed with methanol, and vacuum-dried to obtain a copolymer powder.

Example 4

Electrochemical Copolymerization of N-Octylcarbazole and 3-Methylthiophene

N-octylcarbazole (0.05mol/L) and 3-methylthiophene (0.01mol/L) were dissolved in boron trifluoride ether and added to a three-electrode electrolytic cell, wherein the working electrode was ITO glass; The electrode is a platinum sheet; the reference electrode is a silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.0V. Polymerization time 36h. After the polymerization is completed, precipitate with methanol, filter, wash with methanol, and dry in vacuum to obtain copolymer powder.

Example 5

Electrochemical Copolymerization of N-Hexylcarbazole and 3-Hexylthiophene

Dissolve N-hexylcarbazole (0.1mol/L) and 3-hexylthiophene (0.01mol/L) in boron trifluoride ether and add them to a three-electrode electrolytic cell, wherein the working electrode is ITO glass; the counter electrode is Platinum sheet; the reference electrode is silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.1V. Polymerization time 36h. After the polymerization is completed, precipitate with methanol, filter, wash with methanol, and dry in vacuum to obtain copolymer powder.

Example 6

Electrochemical Copolymerization of 9,9'-Dihexylfluorene and N-Heptylcarbazole

Dissolve 9,9′-dihexylfluorene (0.01mol/L) and N-heptylcarbazole (0.01mol/L) in acetonitrile, and add tetrabutylammonium perchlorate 10 ^-2 mol/L, as electrolyte. Add it to a three-electrode electrolytic cell, in which the working electrode is ITO glass; the counter electrode is platinum sheet; the reference electrode is silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.2V. Polymerization time 6h. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Example 7

Electrochemical Copolymerization of 9,9'-Dihexylfluorene and Benzene

Dissolve 9,9'-dihexylfluorene (0.01mol/L) and benzene (0.01mol/L) in boron trifluoride ether and add them to a three-electrode electrolytic cell, in which the working electrode is ITO glass; the counter electrode is platinum sheet; the reference electrode is silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.1V. Polymerization time 6h. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Example 8

Electrochemical Copolymerization of Benzene and Thiophene

Dissolve benzene (0.01mol/L) and thiophene (0.1mol/L) in boron trifluoride ether and add them to a three-electrode electrolytic cell, wherein the working electrode is ITO glass; the counter electrode is platinum; the reference electrode is Silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.0V. Polymerization time 2h. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Embodiment 9: Electrochemical copolymerization of naphthalene and thiophene

Dissolve naphthalene (0.05mol/L) and thiophene (0.1mol/L) in boron trifluoride ether and add them to a three-electrode electrolytic cell, wherein the working electrode is ITO glass; the counter electrode is platinum; the reference electrode is Silver-silver chloride electrode. The polymerization was carried out by a constant potential method, and the polymerization potential was 1.1V. Polymerization time 2h. After the polymerization is completed, the polymer on the ITO glass is scraped off, washed with absolute ethanol for 30 seconds, filtered, and vacuum-dried to obtain a copolymer powder.

Claims (10)

1. A method for preparing a copolymer luminescent material, characterized in that: the copolymer luminescent material is prepared by copolymerizing two monomers by means of electrochemical polymerization, and the copolymer obtained by homopolymerizing the two monomers respectively Conjugated homopolymers have different energy gaps; the electrochemical polymerization method is as follows: two monomers, electrolytic solvent and supporting electrolyte are added to a three-electrode electrolytic cell to form an electrolyte, and a constant potential method is used for polymerization to obtain a copolymer solution or deposited on the working electrode to obtain a copolymer thin film, and after post-treatment to obtain the copolymer luminescent material; the initial concentrations of the two monomers in the electrolyte are 10 ^-4 -10 mol/L. 2. The preparation method of copolymer luminescent material according to claim 1, characterized in that the two monomers, one of which is selected from one of the following: 9,9'-dialkylfluorene, N- Alkylcarbazole; another monomer selected from one of the following: thiophene, alkylthiophene. 3. The method for preparing a copolymer luminescent material according to claim 1, characterized in that the difference in energy gap of the conjugated homopolymer obtained by homopolymerizing the two monomers is in the range of 0.02eV to 2eV. 4. The preparation method of copolymer luminescent material according to any one of claims 1-3, characterized in that the supporting electrolyte is composed of anion and cation in a ratio of 1:1, and the anion is one or two of the following The mixture of the above: perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, hexafluoroarsenate ion; the cation is a mixture of one or more of the following: lithium ion, tetramethylammonium ion, Tetraethylammonium ion, tetrabutylammonium ion, tetra-n-propylammonium ion, tetra-n-hexylammonium ion. 5. The preparation method of copolymer luminescent material according to claim 4, characterized in that the concentration of the supporting electrolyte in the electrolyte is 10 ^-3 ~ 10 ^-1 mol/L. 6. The method for preparing copolymer luminescent materials according to any one of claims 1-3, characterized in that the electrolytic solvent is one of the following: fluorosulfonic acid, acetonitrile, toluene, ethanol, methanol, chloroform, Dichloromethane, tetrahydrofuran, cyclohexane, propylene carbonate, phenylacetonitrile, diethyl ether, petroleum ether. 7. The method for preparing a copolymer luminescent material according to any one of claims 1-3, characterized in that the electrolytic solvent and the supporting electrolyte are boron trifluoride ether at the same time. 8. The method for preparing a copolymer luminescent material according to any one of claims 1 to 3, characterized in that when the polymerization is carried out by the constant potential method, the specific steps are as follows: apply a constant potential signal to the working electrode, and the range of the constant potential signal is It is 0.8 ~ 2.0V, and the time is 200s ~ 48h. 9. The method for preparing a copolymer luminescent material according to any one of claims 1 to 3, characterized in that the post-treatment adopts the following method: the copolymer film deposited on the working electrode is cleaned, filtered and dried To obtain the final product, the cleaning uses the following solvents: N,N-dimethylacetamide, N,N-dimethylformamide, acetonitrile, toluene, ethanol, methanol, chloroform, Dichloromethane, tetrahydrofuran, cyclohexane, pyridine, propylene carbonate, phenylacetonitrile, diethyl ether, acetic acid, formic acid or petroleum ether. 10. The method for preparing a copolymer luminescent material according to any one of claims 1 to 3, characterized in that the post-treatment adopts the following method: add a precipitation solvent to the obtained copolymer solution to precipitate the copolymer, and filter , washing, and drying to obtain the final product; the precipitation solvent is selected from methanol, ethanol, acetone, acetonitrile, formic acid or acetic acid.