CN111349217B

CN111349217B - Ternary copolymer and preparation method of electric storage device thereof

Info

Publication number: CN111349217B
Application number: CN202010328932.4A
Authority: CN
Inventors: 王淑红; 张洪岩; 仲华; 汪成; 张营娜
Original assignee: Heilongjiang University
Current assignee: Heilongjiang University
Priority date: 2020-04-23
Filing date: 2020-04-23
Publication date: 2023-06-27
Anticipated expiration: 2040-04-23
Also published as: CN111349217A

Abstract

The invention provides a terpolymer and an electric storage device prepared by using the terpolymer as an organic layer. The prepared electric storage device has low starting voltage, high switching current ratio, quick response, repeated cycle reading and writing and excellent performance. The terpolymer synthesis method is simple, the preparation process of the electric storage device is stable, the ternary electric storage performance is realized, industrial production can be realized, and the ternary electric storage device has good application prospect in the field of information storage.

Description

Ternary copolymer and preparation method of electric storage device thereof

Technical Field

The invention belongs to the technical field of organic memory materials, in particular relates to a terpolymer and a synthesis method thereof, and particularly relates to an electric memory device taking the terpolymer as an organic layer and a preparation method thereof.

Background

With the rapid development of information technology, electronic digital products are rapidly updated, so that the demands of people on the electric memory chips are increasing. The technology for manufacturing an electrical storage device by using a conventional inorganic semiconductor material is very mature, so that the electrical storage device is fully applied to various information fields. As the demand for mobile applications continues to drive the development of storage technologies and devices, there is an increasing demand for memory with high capacity, good system performance, low power consumption, smaller size, and lower cost. However, a large number of materials and cost factors limit the miniaturization of the size of the currently mainstream inorganic semiconductor memories. The development of new memory storage structures and materials is coming to new opportunities.

Recently, polymer electric memory devices have attracted great attention as an emerging field in organic electronics. The organic memory device stores data according to high and low conductivity response variations and exhibits dual stability. The particular properties of polymeric materials have gained great attention. The polymer material has good processability and unit size scalability, and can adjust the electrical properties of the material through molecular design and chemical synthesis, so that the polymer material becomes an ideal material for future micro-nano and molecular scale storage materials. Compared with a silicon memory, the memory made of the polymer memory material has the advantages of low cost, simple device structure, easy processing and plasticity, good flexibility, quick response, low power consumption, three-dimensional stacking high-density memory and the like, and particularly can realize industrialized large-area manufacture. The polymer storage material has very wide application prospect in the field of information storage and high-speed calculation.

At present, in the conjugated polymer memory material, the conjugated polymer material with the functionalized side chains has good main chain flexibility, is favorable for the preparation and processing of an organic layer, but has higher starting voltage and lower switching current, so that the memory device has high working voltage and low resolution. The memory material with the main chain of conjugated polymer has large conjugated structure, difficult synthesis, complex preparation method, unfavorable mass production, difficult film formation due to high rigidity and unfavorable device preparation. For example, the conjugated polymer using triphenylamine as electron donor is difficult to dissolve, and the difficulty of preparing the device is increased.

Based on the above problems, there is a need to develop a conductive conjugated polymer which is easy to implement in a synthetic method, can be industrialized, and a memory device prepared therefrom is required to have a high switching current ratio and a low on-voltage.

Disclosure of Invention

In order to solve the problems, the inventor has found through intensive researches that a carbazole-fluorene-benzimidazole terpolymer is simple in synthesis method and easy to process into a film, and the prepared electric storage device has ternary electric storage performance, low on-voltage, high switching current ratio, simple preparation process and low cost, so that the invention is completed.

The invention aims to provide a terpolymer which is polymerized by halogenated carbazole monomers, halogenated benzimidazole monomers and fluorene monomers.

The invention also aims to provide a carbazole-fluorene-benzimidazole terpolymer, which has the following repeating units:

wherein R is ₁ 、R ₂ Each independently is an alkyl group having 3 to 31 carbon atoms, R ₃ 、R ₄ Each independently is hydrogen, alkyl, aryl, or a heterocyclic group.

Another object of the present invention is to provide a carbazole-fluorene-benzimidazole terpolymer having the following structural parts:

wherein, the liquid crystal display device comprises a liquid crystal display device,

R ₁ 、R ₂ is an alkyl group having 3 to 31 carbon atoms;

R ₃ 、R ₄ is hydrogen, alkyl, aryl or heterocyclic group;

n is an integer of 20 to 300.

The terpolymer may be prepared by a process comprising the steps of:

step 1, adding halogenated carbazole monomers, halogenated benzimidazole monomers and fluorene monomers into a solvent, and heating for reaction to obtain a polymer solution;

and step 2, carrying out post-treatment on the polymer solution to obtain the terpolymer.

The invention also aims to provide a preparation method of the terpolymer, which comprises the following steps:

The invention also aims to provide the use of the terpolymer for preparing an electrical storage device.

The invention provides an electric storage device with the terpolymer as an organic layer.

The electrical storage device further includes a substrate layer, a cathode layer, and an anode layer.

The invention also aims to provide a preparation method of the electric storage device, which comprises the following steps:

step a, cleaning a substrate layer;

step b, dispersing the terpolymer in a solvent to obtain a terpolymer solution;

step c, enabling the terpolymer solution to be attached to the cathode layer to form an organic layer;

and d, attaching an anode layer on the organic layer to obtain the organic memory device.

The invention has the following beneficial effects:

(1) The carbazole group has good optical and electrochemical properties, can enhance the hole or electron transmission capability of the material, and can improve the thermodynamic and electrochemical stability of the material.

(2) Benzimidazole group has electron accepting and electron transmitting capacity, and can improve carrier injection balance in device structure.

(3) Polyfluorene is usually used as an electron donor and a charge transport material, has higher mobility of carriers, is a good photoelectric material for transporting the carriers along a conjugated main chain, and can improve HOMO energy level by introducing electron donating groups into polyfluorene.

(4) The fluorenyl, carbazolyl and benzimidazole structures can enhance the charge transmission capability of the conjugated polymer, reduce the starting voltage and improve the switching current ratio, and the copolymer is easy to form a film and improves the processability of the polymer.

(5) The prepared electric storage device has low starting voltage, low energy consumption, high switching current ratio, high resolution, low error reading rate, quick response, capability of performing repeated cycle reading and writing and excellent performance.

(6) The terpolymer synthesis method is simple, the preparation process of the electric storage device is easy to realize, and industrial production can be realized.

Drawings

FIG. 1 shows a schematic diagram of the structure of an electrical storage device of the present invention;

FIG. 2 shows the nuclear magnetic resonance spectrum of the terpolymer of example 1 of the present invention;

fig. 3 is a graph showing a current-voltage characteristic curve test of the electric storage device in embodiment 2 of the present invention;

fig. 4 is a graph showing a switching current ratio-voltage characteristic curve test of the electric storage device in embodiment 2 of the present invention.

Detailed Description

The features and advantages of the present invention will become more apparent and evident from the following detailed description of the invention.

The intermediate terpolymer is polymerized by halogenated carbazole monomers, halogenated benzimidazole monomers and fluorene monomers.

The terpolymer of the present invention has the following repeating units:

In the invention, the carbazole-fluorene-benzimidazole terpolymer has the following structural parts:

R ₁ 、R ₂ each independently is an alkyl group having 3 to 31 carbon atoms, preferably an alkyl group having 6 to 21 carbon atoms, more preferably 7-tridecyl, 8-pentadecyl and 9-heptadecyl;

R ₃ 、R ₄ each independently is hydrogen, alkyl, aryl, or a heterocyclic group, preferably hydrogen or a heterocyclic group, more preferably hydrogen;

m is an integer of 20 to 300, preferably an integer of 30 to 200, more preferably an integer of 30 to 100. n is an integer of 20 to 300, preferably an integer of 30 to 200, more preferably an integer of 30 to 100. Preferably, m and n have the same value.

The preparation method of the carbazole-fluorene-benzimidazole terpolymer comprises the following steps:

step 1, adding halogenated carbazole monomers, halogenated benzimidazole monomers and fluorene monomers into a solvent, and heating for reaction to obtain a polymer solution.

The halogenated carbazole monomer is halogenated N-alkyl carbazole, and the alkyl is alkyl containing 3-31 carbon atoms, preferably alkyl containing 6-21 carbon atoms, more preferably 7-tridecyl, 8-pentadecyl and 9-heptadecyl.

Preferably, the halogenated carbazole monomers are substituted in the 2 and 7 positions with a halogen selected from chlorine, bromine, iodine, preferably bromine or iodine.

The carbazole group has good hole transmission performance, meanwhile, the carbazole group has active modification points, the structure has strong flexibility, azo can be used as a bridge bond to introduce other groups, and the storage performance of the electric storage device can be adjusted by designing substituents. The carbazole group is designed on the main chain, so that the main chain conjugated polymer electricity storage material has better charge flow. Carbazole groups are used as electron donors, and when electron withdrawing groups are introduced, ternary storage performance can be achieved by designing the polymer structure.

The halogenated benzimidazole monomer is selected from benzimidazolo heterocyclic groups selected from thiophene groups, thiazole groups, furan groups, pyridine groups, pyrrole groups, quinoline groups, isoquinoline groups, acridine groups, indole groups, more preferably from benzimidazolo isoindoline groups or benzimidazolo indoline groups, such as benzimidazolo benzi isoindolinone groups.

Wherein, the 4-position and 7-position of benzimidazole in the halogenated benzimidazole monomer are introduced with halogenated groups, and halogen of the halogenated groups is selected from chlorine, bromine and iodine, preferably bromine or iodine. In a preferred mode of the invention, 1, 4-dibromo-12H-benzo [5,6] isoindol [2,1-a ] benzimidazol-12-one is used as the halogenated benzimidazole monomer to participate in the polymerization.

The fluorene monomer is alkyl fluorene, the alkyl is alkyl containing 3-31 carbon atoms, preferably alkyl containing 6-21 carbon atoms, more preferably 7-tridecyl, 8-pentadecyl and 9-heptadecyl.

Preferably, the fluorene monomers bear a boric acid-based group or a boric acid ester-based group such as an alkyl boric acid group, an aryl boric acid group, an alkenyl boric acid group, an alkyl boric acid ester group, an aryl boric acid ester group or an alkenyl boric acid ester group at positions 2 and 7, preferably an alkyl boric acid ester group, an aryl boric acid ester group or an alkenyl boric acid ester group, more preferably an alkyl boric acid ester group such as 9, 9-dioctylfluorene-2, 7-di (1, 3-propanediol) diborate.

The polyfluorene compound has higher chemical stability and thermal stability. The polyfluorene compound contains two benzene ring structures which are in the same plane and are connected through a single carbon-carbon bond and a methylene bridge bond, so that the polyfluorene compound not only has a higher conjugated system, but also has a regular structure so as to further improve the space and performance stability of the polyfluorene compound. The 2,7 and 9 positions in fluorene molecule have active carbon atoms, and other substituent groups are easy to introduce for functional modification, so that functionalization is realized. Fluorene, which is a good hole transport material, can be a donor or acceptor by modification of different groups. Benzimidazole group is used as electron acceptor, and its high conjugation degree makes the copolymer possess excellent electron flowability. Carbazole and fluorene are used as electron donors, so that the HOMO energy level can be effectively improved, hole injection and transportation are enhanced, and the device has excellent electrochemical performance. The polymer is easy to process, low in cost and excellent in performance.

The reaction is carried out under the catalysis of a catalyst. The catalyst is selected from palladium salts such as palladium chloride or palladium acetate, palladium on carbon, inorganic oxide supported palladium such as Pd/Al ₂ O ₃ Or Pd/MgO, palladium complexes, e.g. Pd (AsPh ₃ ) ₄ 、Pd(n-Bu ₃ P) ₄ 、Pd((MeO) ₃ P) ₄ Preferably a palladium salt or complex of palladium, more preferably a complex of palladium, such as tetrakis (triphenylphosphine).

The solvent is an organic solvent selected from alkanes such as octane, N-heptane, ethers such as petroleum ether, aromatic hydrocarbons such as toluene, xylene, sulfones such as dimethyl sulfoxide, dimethyl sulfone, amides such as N, N-dimethylformamide, preferably selected from aromatic hydrocarbon solvents, more preferably toluene or xylene. In the invention, in order to better dissolve and disperse the palladium catalyst in the solvent, the solvent used has the function of a water carrying agent while dissolving the reactant, and the reduction of the water content in the solvent can better dissolve the catalyst in the reaction system to play a catalytic role.

Preferably, a solution of an alkaline substance is added to the reaction, the alkaline substance being selected from soluble carbonates, acetates, phosphates or hydroxides, preferably from alkali metal carbonates or alkali metal acetates, more preferably alkali metal carbonates.

In the preferred mode of the invention, when the reaction is carried out, the halogenated carbazole monomer and the halogenated benzimidazole monomer respectively carry out oxidation addition reaction with a palladium catalyst and then are converted into an organic palladium hydroxide intermediate product under the action of an alkali reagent, and simultaneously, the alkyl borate group has stronger rich electrical property in an alkaline environment, so that the halogenated carbazole monomer and the halogenated benzimidazole monomer migrate to the metal center Pd of the organic palladium hydroxide intermediate product and are coupled in a counter manner, and the bonding of the halogenated carbazole monomer, the fluorene monomer and the halogenated benzimidazole monomer is respectively completed, thereby obtaining the terpolymer.

The reaction temperature is 80 to 130 ℃, preferably 90 to 120 ℃, more preferably 100 to 110 ℃.

The reaction time is 20 to 80 hours, preferably 35 to 65 hours, more preferably 45 to 55 hours.

The copolymerization reaction has mild condition, high catalytic efficiency, high selectivity and few byproducts, can ensure that the imidazole structure is completely reserved and cannot be destroyed in the reaction process, and the coupling reaction is not greatly influenced by steric hindrance, so that the halogenated carbazole monomer, the halogenated benzimidazole monomer and the fluorene monomer can smoothly react to complete the ternary polymerization process.

The molar ratio of the fluorene monomer, the halogenated carbazole monomer and the halogenated benzimidazole monomer is (1.5-3.5) to 1:1, preferably (1.8-2.5) to 1:1, and more preferably (2.0-2.2) to 1:1. In the invention, the halogenated carbazole monomer and the halogenated benzimidazole monomer are respectively bonded with the fluorene monomer of the borate group through coupling reaction, which is beneficial to weakening the boron removal effect in the reaction process and improving the utilization rate of raw materials compared with the use of the borate group.

The molar ratio of the fluorene monomer to the catalyst is 1 (0.001 to 0.2), preferably 1 (0.005 to 0.1), more preferably 1 (0.02 to 0.05). In the reaction in the step 1, the rate of the oxidative addition of the halogenated carbazole monomer and the halogenated benzimidazole monomer with the zero-valent palladium is a main step affecting the reaction rate, and if the content of the catalyst is too small, the rate of the whole reaction is reduced; if the catalyst content is too large, the reaction rate does not increase any more after exceeding a certain amount, and the excessive catalyst increases the production cost.

The molar volume ratio of the fluorene monomer to the solvent is 0.06mol (4-10) mL, preferably 0.06mol (5-9) mL, more preferably 0.06mol (6-8) mL.

The concentration of the alkaline substance solution is 1.5 to 5mol/L, preferably 2.5 to 4mol/L, more preferably 2.8 to 3.2mol/L. Too strong a basicity can cause self-coupling of the haloaryl groups.

The volume ratio of the solvent to the alkaline substance solution is 1 (0.6-2), preferably 1 (0.8-1.5), more preferably 1 (1.0-1.2).

The reaction is carried out under an inert gas atmosphere, which is nitrogen or argon, preferably nitrogen.

In a preferred embodiment of the invention, halogenated benzimidazole monomers are selected to participate in the coupling reaction to synthesize the terpolymer. The preparation method of the halogenated benzimidazole monomer comprises the following steps:

step 1-1, adding aromatic dianhydride and halogenated diamine into a solvent, and heating for reaction to obtain a reaction solution.

The aromatic dicarboxylic anhydride is selected from phthalic anhydride or condensed ring dicarboxylic anhydride, preferably from phthalic anhydride, naphthalene dicarboxylic anhydride or anthracene dicarboxylic anhydride, more preferably 2, 3-naphthalene dicarboxylic anhydride.

The halogenated diamine is two amino groups respectively positioned on two adjacent carbon atoms, and is selected from dihalogenated aryl diamine, preferably dihalogenated phenylenediamine, more preferably 3, 6-dibromo-1, 2-phenylenediamine or 3, 6-diiodo-1, 2-phenylenediamine.

The solvent is selected from alkyl carboxylic acid solvents, preferably alkyl monocarboxylic acids, more preferably glacial acetic acid or propionic acid.

In the invention, the benzimidazole structure can be obtained by utilizing the reaction of aromatic dianhydride and halogenated diamine. Imidazole is a five-membered heterocyclic compound containing two nitrogen atoms, which has a closed large pi bond, N atoms contain lone pair electrons, the imidazole ring has a coplanar structure, and carbon atoms and nitrogen atoms on the imidazole ring are positioned on the same plane, and the imidazole ring belongs to a non-central symmetrical structure. The unique heterocyclic structure of benzimidazole compounds enables the benzimidazole compounds to have excellent electron transmission performance. The compound has the characteristics of larger coplanarity, stronger pi conjugated system, strong optical and electrical activity, thermal stability, easy structure modification and the like. Different functional groups can be introduced or switched on the aromatic ring to achieve the purpose of different applications.

The molar ratio of the aromatic dicarboxylic anhydride to the halogenated diamine is 1 (0.7-2.5), preferably 1 (0.9-1.5), and more preferably 1 (1.0-1.2).

The molar volume ratio of the aromatic diacid anhydride to the solvent is 0.0075mol (5-25) mL, preferably 0.0075mol (8-20) mL, more preferably 0.0075mol (9-18) mL.

The reaction temperature is 90 to 120 ℃, preferably 100 to 115 ℃, more preferably 105 to 110 ℃.

The reaction time is 3 to 18 hours, preferably 5 to 12 hours, more preferably 6 to 8 hours.

And step 1-2, carrying out post-treatment on the reaction liquid to obtain the halogenated benzimidazole monomer.

The post-treatment process comprises cooling, filtering, washing, drying, purifying and drying after purifying.

The reaction solution was cooled to room temperature, and a solid crude product was gradually precipitated during the cooling. After precipitation, the reaction solution was filtered to separate out a crude product. The filtration is preferably suction filtration.

The washing process is to wash the crude product to neutrality with a solvent that is not capable of reacting with or dissolving the crude product, preferably ethanol or water, more preferably water, such as deionized water, to remove impurity molecules.

After washing, the crude product is dried, preferably under vacuum, at a temperature of 50 to 130 ℃, preferably 70 to 100 ℃, more preferably 80 to 85 ℃, for a time of 5 to 25 hours, preferably 8 to 18 hours, more preferably 10 to 15 hours, such as 12 hours, and at a pressure of-80 to-10 KPa, preferably-50 to-20 KPa, more preferably-30 to-29 KPa.

Preferably, the crude product is purified by extraction, crystallization or column chromatography, preferably crystallization or column chromatography, more preferably column chromatography. The solid phase of the column chromatography is silica gel powder, the mobile phase is mixed liquid of dichloromethane and petroleum ether, the volume ratio of the dichloromethane to the petroleum ether is 3:1, and the solvent is removed by rotary evaporation of the solution to obtain a final product. The column chromatography method is simple, and the purity of the obtained monomer is extremely high.

In step 2, the post-treatment process comprises crystallization, washing and drying.

The crystallization is to add the polymer solution into the precipitant to separate the polymer from the solution. The precipitant is selected from alkanes, alcohols, ketones, ethers, water, preferably from hexane, methanol, ethanol, acetone, diethyl ether, petroleum ether, water, more preferably methanol or acetone. Preferably, during crystallization, an ice solvent is used to promote polymer precipitation.

The washing is to wash the polymer with a precipitant solvent. The polymer is long-chain molecules, so that impurity molecules such as small molecules are easy to wrap, and the impurity molecules in the polymer need to be removed in order to ensure the purity and the conductivity of the polymer. After washing, the polymer solution is filtered, preferably by suction, to isolate the polymer product.

The drying is preferably vacuum drying. The drying temperature is 30-120 ℃, preferably 50-90 ℃, more preferably 60-65 ℃; the time of vacuum drying is 5 to 25 hours, preferably 8 to 18 hours, more preferably 10 to 15 hours, such as 12 hours; the vacuum drying pressure is-80 to-10 KPa, preferably-50 to-20 KPa, more preferably-35 to-25 KPa. The polymer has a long molecular chain, is easy to wind, has strong adsorption or occlusion effect on a solvent and a precipitant, and is difficult to dry. The invention adopts high vacuum degree and is matched with the selection of the precipitant, so that the effect of removing the precipitant can be achieved well.

Preferably, the post-treatment process further comprises purification.

In a preferred form of the invention, the purification is carried out by Soxhlet extraction. The method has the advantages of simple operation, solvent saving and high purification efficiency.

The purification solvent is a reaction solvent, and acetone is preferably used.

The purification temperature is 30 to 150 ℃, preferably 50 to 120 ℃, more preferably 60 to 90 ℃.

The purification time is 24 to 80 hours, preferably 35 to 70 hours, more preferably 40 to 55 hours.

The terpolymer provided by the invention can be used for manufacturing semiconductor materials of electric storage devices. The conjugated polymer with electron donating groups introduced into the main chain of the polymer has lower HOMO energy level, so that the copolymer has excellent open-circuit voltage, benzimidazole groups are introduced into the conjugated polymer as excellent electron-deficient acceptor elements, the conjugated polymer has molecular charge transfer, and the path of the benzimidazole groups is benzimidazole to benzisotalolinone, so that the benzimidazole monomers serve as two different defect subunits to form a donor-acceptor structure terpolymer, and the intramolecular charge transfer can be performed, thereby effectively reducing the band gap of the conjugated polymer.

In the present invention, an electrical storage device is prepared using a terpolymer as an organic layer. The electrical storage device includes a substrate layer, a cathode layer, an organic layer, and an anode layer, as shown in fig. 1.

The electrical memory device using the terpolymer as the organic layer exhibits ternary Flash-type erasable electrical memory properties. In the ground state, the groups in the polymer chain are supposed to be in a random disordered state, charge carrier or hole transitions are very difficult, and the electrical storage device is in an OFF state; under the action of an electric field, the charged carbazole groups and fluorene groups can attract benzimidazole groups to carry out conformational ordering to form an ordered configuration, and the ordered configuration reaches an ON1 state; when the electric field strength is further enhanced, the active charge carries out delocalization between regular conformations and moves towards the cathode, and finally a high-conductivity channel is formed to reach an ON2 state; when the voltage is turned off, the polymer may remain on as shown in fig. 2.

When an opposite voltage is applied to the electric storage device, holes which are captured by the trap can be re-attracted to the interface of the electrode and the polymer to be recombined with electrons, so that the polymer is restored to the original state, and the purpose of erasure is achieved, as shown in fig. 2.

The organic layer prepared by the terpolymer has good thermal stability and film forming property. The prepared electric storage device has low starting voltage (NO 1 state can reach-0.75V), low energy consumption, long service life of the device and high switching current ratio (OFF: ON1: ON2 is 1:10) ^1.3 :10 ^4.0 ) The memory density is greatly improved, the resolution ratio is high, the misreading rate is low, the response can be fast, the repeated cycle reading and writing can be performed, and the performance is excellent.

The invention provides a preparation method of the electric storage device, which comprises the following steps:

and a step a, cleaning the substrate layer.

The substrate layer is attached with a cathode layer.

The cathode layer is selected from tin oxide glass (ITO), conductive polymers, graphene or a metal with good conductivity, such as Al, cu, au, preferably ITO or a conductive metal, more preferably ITO or Al. Preferably, the cathode layer is deposited on the glass substrate by vacuum evaporation.

The substrate layer cleaning is to clean the substrate layer with the cathode layer by using a solvent, preferably ultrasonic cleaning.

The solvent is water, methanol, absolute ethyl alcohol, cyclohexanone or acetone, preferably one or more of deionized water, absolute ethyl alcohol or acetone, more preferably, the substrate layer is sequentially cleaned in the order of deionized water, absolute ethyl alcohol, acetone, absolute ethyl alcohol and deionized water, and impurity substances on the substrate are removed. The substrate layer after washing is preferably stored in absolute ethanol.

And b, dispersing the terpolymer in a solvent to obtain a terpolymer solution.

The solvent is an organic solvent, preferably selected from aromatic solvents such as toluene, xylene, ethers such as petroleum ether, sulfones such as dimethyl sulfoxide, preferably selected from aromatic solvents, more preferably toluene. The toluene in the invention can well dissolve and disperse the terpolymer and is easy to remove.

The concentration of the polymer solution is 1 to 30mg/mL, preferably 3 to 15mg/mL, more preferably 5 to 12mg/mL. The concentration of the polymer solution directly affects the thickness of the organic layer, if the concentration of the polymer solution is too high, the polymer is not well dispersed, a uniform organic film is not easily formed, and if the concentration of the polymer solution is too low, the formed organic film is thinner, and the performance of the electric storage device is affected.

And c, attaching the terpolymer solution on the cathode layer to form an organic layer.

The polymer solution may be applied to the cathode layer by a film forming method such as spin coating, spray coating, dip coating, roll coating or ink jet printing, preferably spin coating, roll coating or spray coating, more preferably spin coating or spray coating. The organic layer obtained by the spin coating or spraying method is uniformly distributed, and the preparation method is low in production cost and easy for mass production.

The coated organic layer is preferably dried in vacuo to remove the solvent. The drying temperature is 50-130 ℃, preferably 70-120 ℃, more preferably 80-115 ℃; the time of vacuum drying is 10 to 40 hours, preferably 15 to 30 hours, more preferably 18 to 25 hours; the vacuum drying pressure is-80 to-10 KPa, preferably-50 to-20 KPa, more preferably-35 to-25 KPa.

The thickness of the organic layer 3 is 100 to 300nm, preferably 150 to 280nm, more preferably 220 to 260nm. If the organic layer is too thin, it may result in a low barrier and electrons are difficult to capture. Too thick an organic layer can result in too high a potential barrier, and charge carriers are difficult to inject into the entire organic layer, impairing the charge transport capability in the thin film.

The anode layer is a metal layer, preferably Al, cu, au or Pt, and more preferably Al in view of conductivity and manufacturing cost.

Preferably, the anode layer is prepared by vacuum evaporation.

The thickness of the anode layer is 120 to 600nm, preferably 200 to 500nm, more preferably 250 to 350nm.

The area of the anode layer is 0.1-8 mm ² Preferably 0.25 to 5mm ² More preferably 0.5 to 3mm ² 。

The organic layer prepared by the terpolymer provided by the invention has good thermal stability and film forming property, and the electric storage device has low starting voltage, high switching current ratio, high resolution, low misreading rate, quick response, capability of performing repeated cycle reading and writing and excellent performance. And the conjugated polymer has simple synthesis method, mature preparation process of the electric memory device and can realize industrial production.

Examples

Example 1

At N ₂ Under the atmosphere, 1.49g of 2, 3-naphthalene dicarboxylic anhydride, 0.27g of 3, 6-dibromo-1, 2-phenylenediamine and 10mL of glacial acetic acid are placed in a reaction vessel, stirred and heated to 108 ℃, and the solvent is refluxed for constant temperature reaction for 6 hours.

After the reaction, the reaction solution was cooled to room temperature, and after the crude product was gradually precipitated, it was filtered and washed with deionized water to neutrality. And (3) putting the obtained crude product into a vacuum drying oven for drying, wherein the temperature of vacuum drying is 85 ℃, the time of vacuum drying is 12 hours, and the pressure of vacuum drying is-30 KPa. Separating and purifying the dried crude product by column chromatography, wherein the stationary phase of the chromatographic column is silica gel powder, and the liquid phase is dichloromethane: petroleum ether (3:1) to obtain benzimidazole monomer 1, 4-dibromo-12H-benzo [5,6] isoindolo [2,1-a ] benzimidazole-12-ketone.

Under nitrogen atmosphere, 0.3mmol of 1, 4-dibromo-12H-benzo [5,6]]Isoindolo [2,1-a ]]Benzimidazole-12-one, 0.3mol of 2, 7-dibromo-9- (1-octylnonyl) -9H-carbazole and 0.6mmol of di (1, 3-propanediol) 9, 9-dioctylfluorene-2, 7-diboronate were added to a reaction vessel, 7mL of toluene and an equal volume of 3mol/L potassium carbonate solution were added, and 2mol% of palladium catalyst Pd (PPh ₃ ) ₄ The temperature was raised to 108℃with stirring, and the reaction was carried out for 48 hours.

After the reaction, slowly dripping the polymer solution into 200mL of ice methanol to precipitate a product, washing with methanol, filtering, repeating for 3 times, and drying the obtained product in a vacuum drying oven, wherein the vacuum drying temperature is 65 ℃, the vacuum drying time is 12h, and the vacuum drying pressure is-30 KPa.

And after drying, carrying out Soxhlet extraction and purification, wherein the purification solvent is acetone, the Soxhlet extraction temperature is 70 ℃, and the Soxhlet extraction time is 48 hours, so as to obtain the carbazole-fluorene-benzimidazole terpolymer. And drying in a vacuum drying oven, wherein the vacuum drying temperature is 60 ℃, and the vacuum drying time is 12 hours.

Example 2

Sequentially placing the substrate layer with the ITO cathode layer in deionized water, absolute ethyl alcohol, acetone, absolute ethyl alcohol and deionized water for cleaning for 30min, and storing in absolute ethyl alcohol after cleaning.

The terpolymer prepared in example 1 was dissolved in toluene to give a polymer solution with a concentration of 5 mg/mL. And (3) dropwise adding the polymer solution on the washed cathode layer, uniformly dispersing the polymer solution by a spin coater, and removing the toluene solvent by vacuum drying to obtain an organic layer with the thickness of 250 nm.

Attaching a metal electrode Al to the organic layer by vacuum evaporation, wherein the thickness and the area of the metal electrode are respectively 300nm and 1.0mm ² . Obtaining the Flash memory type sandwich structure organic electric memoryThe structural schematic diagram of the piece is shown in figure 1.

Experimental example

Experimental example 1

The terpolymer prepared in example 1 was analyzed by nuclear magnetic resonance hydrogen spectroscopy using an INOVA 400MHz high resolution nuclear magnetic resonance spectrometer (TMS as an internal standard), CDCl ₃ Is solvent, and the spectrum is shown in figure 2.

From the graph, the chemical shift delta is the chemical shift of characteristic peaks of carbazolyl at 4.55ppm, which indicates that the terpolymer containing carbazolyl is synthesized. ¹ H-NMR (δppm): 8.67-7.06 (characteristic peak of aromatic ring), 4.55 (characteristic peak of carbazole), 2.41-0.27 (characteristic peak of alkyl chain).

Experimental example 2

The electrical storage device prepared in example 2 was tested for electrical storage performance, the current-voltage characteristic curve (I-V) is shown in fig. 3, and the switching current ratio-voltage diagram is shown in fig. 4.

The first step voltage sweep is performed on the memory device with two current boost states in the voltage region of 0V to-6V. A current increase jump occurs at a voltage of-0.75V, which can be considered to be a transition from a low conduction state (OFF state) to an intermediate conduction state (ON 1 state), a second current increase jump occurs at a voltage of-1.15V, the electrical memory device transitions from the intermediate conduction state (ON 1 state) to a high conduction state (ON 2), and then a second step of 0V to-6V scans, the device is always in the high conduction state, indicating that the device can implement a ternary memory function, and that a write can be read multiple times.

And thirdly, scanning the memory device in a voltage region of 0V to 6V, and when the voltage is increased to 3.75V, reducing the device from a high conduction state (ON 2) to a low conduction state (OFF) to restore the device to an OFF state, wherein the data of the electrical memory device are erased. The memory device can still maintain a stable state after repeated voltage scanning for 200 min. Therefore, the memory device in the present invention is described as a ternary Flash memory device.

As can be seen from fig. 4, the maximum switching current ratio of the memory device is: OFF: ON1: ON2 = 1:10 ^1.3 :10 ^4.0 Indicating that the device has high storage density, can precisely control the on state and the off state, and is faultyThe rate is low.

The present invention has been described in detail in connection with the detailed description and/or the exemplary examples and the accompanying drawings, but the description is not to be construed as limiting the invention. It will be understood by those skilled in the art that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, and these fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. A terpolymer characterized in that the terpolymer has the following moieties:

，

n is an integer from 30 to 100, m is an integer from 30 to 100, and m and n have the same value;

the R is ₁ 、R ₂ 9-heptadecyl;

the R is ₃ 、R ₄ Is hydrogen;

the terpolymer is polymerized by halogenated carbazole monomers, halogenated benzimidazole monomers and fluorene monomers, and specifically comprises the following steps:

the reaction is carried out under the catalysis of a catalyst, the catalyst is a palladium complex,

the halogenated carbazole monomer is halogenated N-alkyl carbazole, the alkyl is 9-heptadecyl, the 2 and 7 positions of the halogenated carbazole monomer are substituted by halogen, the halogen is bromine or iodine,

the halogenated benzimidazole monomer is 1, 4-dibromo-12H-benzo [5,6] isoindolo [2,1-a ] benzimidazole-12-ketone,

the fluorene monomer is 9, 9-dioctylfluorene-2, 7-diboronic acid di (1, 3-propylene glycol) ester;

2. A process for preparing a terpolymer according to claim 1, comprising the steps of:

3. The method according to claim 2, wherein in step 1, the halogenated benzimidazole monomer is prepared by the following method:

step 1-1, adding aromatic dianhydride and halogenated diamine into a solvent, and heating for reaction to obtain a reaction solution;

step 1-2, carrying out post-treatment on the reaction solution to obtain halogenated benzimidazole monomers;

in the step 1-1 of the process,

the aromatic dicarboxylic anhydride is 2, 3-naphthalene dicarboxylic anhydride,

the halogenated diamine is 3, 6-dibromo-1, 2-phenylenediamine or 3, 6-diiodo-1, 2-phenylenediamine.

4. A method according to claim 3, wherein in step 1-1, the solvent is selected from the group consisting of alkyl carboxylic acid solvents.

5. The method according to claim 3, wherein in the step 1-1, the reaction temperature is 90-120 ℃ and the reaction time is 3-18 h.

6. A method according to claim 3, wherein in step 1-2, the post-treatment process comprises cooling, filtering, washing, drying, purifying and drying after purifying.