CN111349217A

CN111349217A - Terpolymer and preparation method of electric storage device thereof

Info

Publication number: CN111349217A
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: 2020-06-30
Anticipated expiration: 2040-04-23
Also published as: CN111349217B

Abstract

The present invention provides a terpolymer and uses the terpolymer for the preparation of an electrical memory device for an organic layer. The prepared electric storage device has low starting voltage, high switching current ratio, quick response, capability of repeated cyclic reading and writing and excellent performance. The terpolymer has the advantages of simple synthesis method, stable preparation process of the electric storage device, ternary electric storage performance, realization of industrial production and good application prospect in the field of information storage.

Description

Terpolymer and preparation method of electric storage device thereof

Technical Field

The invention belongs to the technical field of organic storage materials, particularly relates to a terpolymer and a synthetic method thereof, and particularly relates to an electric storage device taking the polymer 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 demand of people on electric memory chips is increasing day by day. The technology of preparing an electrical memory device by using a traditional inorganic semiconductor material is mature, so that the electrical memory device can be fully applied to various information fields. As the demand for mobile applications continues to drive the development of memory technologies and devices, there is an increasing demand for memories having high capacity, good system performance, low power consumption, smaller size and lower cost. However, the size miniaturization of the inorganic semiconductor memory that is currently mainstream is limited by a large number of materials and cost factors. The development of new memory storage structures and materials is facing new opportunities.

Recently, polymer electrical memory devices have attracted considerable attention as an emerging field in organic electronics. Organic electrical memory devices store data according to high and low conductivity response changes and exhibit bistability. The special properties of polymer materials are of great interest. The polymer material has good processing performance and unit size scalability, and the electrical properties of the material can be adjusted through molecular design and chemical synthesis, so that the polymer material becomes an ideal material for future micro-nano and molecular scale device storage materials. Compared with a silicon memory, the memory made of the high polymer memory material has the advantages of low cost, simple device structure, easiness in processing, plasticity, good flexibility, quick response, low power consumption, three-dimensional stacking, high-density storage and the like, and particularly can realize industrialized large-area manufacturing. The polymer memory material has very wide application prospect in the fields of information storage and high-speed calculation.

At present, in the conjugated polymer memory material, the conjugated polymer material for functionalizing the side chain has good main chain flexibility and is beneficial to the preparation and processing of an organic layer, but the starting voltage is higher and the switching current is lower, so that the working voltage of a memory device is high and the resolution is low. The storage material with the main chain of the conjugated polymer is often too large in conjugated structure, difficult to synthesize, complex in preparation method and not beneficial to large-scale production, and the storage material is difficult to form a film due to high rigidity and is not beneficial to preparation of devices. For example, a conjugated polymer using triphenylamine as an electron donor is difficult to dissolve, and the difficulty of device preparation is increased.

In view of the above problems, there is a need to develop a conductive conjugated polymer whose synthesis method is easy and can be industrially used, and a memory device prepared therefrom is required to have a high switching current ratio and a low turn-on voltage.

Disclosure of Invention

In order to solve the problems, the inventors have intensively studied and found that the 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 starting voltage, high switching current ratio, simple preparation process and low cost, thereby completing the invention.

The invention aims to provide a terpolymer which is prepared by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

It is also an object of the present invention to provide a carbazole-fluorene-benzimidazole terpolymer, the conjugated polymer having the following repeating units:

wherein R is₁、R₂Each independently an alkyl group having 3 to 31 carbon atoms, R₃、R₄Each independently hydrogen, alkyl, aryl or heterocyclic.

Another object of the present invention is to provide a carbazole-fluorene-benzimidazole terpolymer, the conjugated polymer having the following structural moiety:

wherein the content of the first and second substances,

R₁、R₂is an alkyl group having 3 to 31 carbon atoms;

R₃、R₄is hydrogen, alkyl, aryl or heterocyclic group;

n is an integer of 20 to 300.

The terpolymer can be prepared by a method comprising 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;

and 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 said terpolymer for the preparation of an electrical storage device.

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

The electrical memory 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;

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 electric storage device.

The invention has the following beneficial effects:

(1) the carbazole group has good optical and electrochemical properties, and not only can enhance the hole or electron transmission capability of the material, but also can improve the thermodynamic and electrochemical stability of the material.

(2) The benzimidazole group has electron accepting and electron transmitting capacity and can play a role in improving carrier injection balance in a device structure.

(3) Polyfluorene is generally used as an electron donor and a charge transport material, has higher carrier mobility, is a good photoelectric material because the carrier is transported along a conjugated main chain, and can improve the HOMO energy level by introducing an electron-donating group into polyfluorene.

(4) The fluorenyl, carbazolyl and benzimidazole structures can enhance the charge transmission capability of the conjugated polymer, reduce the turn-on 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 ratio, low misreading rate, quick response, 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 structural diagram of an electrical memory device of the present invention;

FIG. 2 shows the NMR spectra of the terpolymer of example 1 of the present invention;

FIG. 3 is a test chart showing a current-voltage characteristic curve of an electric memory device in embodiment 2 of the present invention;

fig. 4 shows a test chart of a switching current ratio-voltage characteristic curve of an electric memory device in embodiment 2 of the present invention.

Detailed Description

The present invention will now be described in detail by way of specific embodiments, and features and advantages of the present invention will become more apparent and apparent from the following description.

The medium ternary copolymer is prepared by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

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

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

wherein the content of the first and second substances,

R₁、R₂each independently 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;

R₃、R₄each independently is hydrogen, an alkyl, an 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, and more preferably 7-tridecyl, 8-pentadecyl and 9-heptadecyl.

Preferably, the halocarbazole-based monomers are substituted at 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, simultaneously has active modification points, has strong flexibility in structure, can introduce other groups by taking azo as a bridge bond, and can adjust the storage performance of the electric storage device by designing a substituent. The carbazole group is designed on the main chain, so that the main chain conjugated polymer electric storage material has better charge circulation. The carbazole group is used as an electron donor, and when an electron-withdrawing group is introduced, the ternary storage performance can be realized by designing a polymer structure.

The halogenated benzimidazole monomer is selected from benzimidazole heterocyclic groups, and the heterocyclic groups are selected from thiophene groups, thiazole groups, furan groups, pyridine groups, pyrrole groups, quinoline groups, isoquinoline groups, acridine groups and indole groups, and are preferably selected from benzimidazole isoindoline groups or benzimidazole isoindoline groups, such as benzimidazole benzisothiazolinone groups.

Halogenated groups are introduced into the 4-position and the 7-position of benzimidazole in the halogenated benzimidazole monomer, 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] isoindolo [2,1-a ] benzimidazole-12-ketone is used as a halogenated benzimidazole monomer to participate in polymerization.

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

Preferably, the fluorene monomer carries boronic acid-based groups or boronic ester-based groups at the 2 and 7 positions, such as alkyl boronic acid groups, aryl boronic acid groups, alkenyl boronic acid groups, alkyl boronic ester groups, aryl boronic ester groups or alkenyl boronic ester groups, preferably alkyl boronic ester groups, aryl boronic ester groups or alkenyl boronic ester groups, more preferably alkyl boronic ester groups, such as 9, 9-dioctylfluorene-2, 7-diboronic acid di (1, 3-propanediol) ester.

The polyfluorene compound has high chemical stability and thermal stability. The polyfluorene compound contains two benzene ring structures in the same plane and is connected through a carbon-carbon single bond and a methylene bridge bond, so that the compound has a higher conjugated system, and the regular structure of the compound improves the stability of the space and performance of the compound. The 2,7 and 9 positions in the fluorene molecule have relatively active carbon atoms, so that other substituent groups are easily introduced for functional modification, and functionalization is realized. Fluorene as a good hole transport material can be a donor or an acceptor through modification of different groups. The benzimidazole group is used as an electron acceptor, and the high conjugation degree of the benzimidazole group enables the copolymer to have excellent electron mobility. Carbazole and fluorene are used as electron donors, so that the HOMO energy level can be effectively improved, hole injection and transport 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, palladium on inorganic oxides, such as Pd/Al₂O₃Or Pd/MgO, palladium complexes, e.g. Pd (AsPh)₃)₄、Pd(n-Bu₃P)₄、Pd((MeO)₃P)₄Preferably a palladium salt or a palladium complex, more preferably a palladium complex, such as tetrakis (triphenylphosphine).

The solvent is an organic solvent selected from alkanes such as octane and N-heptane, ethers such as petroleum ether, aromatic hydrocarbons such as toluene and xylene, sulfones such as dimethyl sulfoxide and 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 used solvent has the function of a water-carrying agent while dissolving the reactants, and the catalyst can be better dissolved in the reaction system to play a catalytic role by reducing the water content in the solvent.

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

In a preferred mode of the invention, during the reaction, after the halogenated carbazole monomer and the halogenated benzimidazole monomer respectively undergo an oxidation addition reaction with a palladium catalyst, the reaction is converted into an organic palladium hydroxide intermediate product under the action of an alkali reagent, and meanwhile, an alkyl borate group has strong electric richness in an alkaline environment, so that the halogenated carbazole monomer and the halogenated benzimidazole monomer migrate to a metal center Pd of the organic palladium hydroxide intermediate product and are subjected to inverse coupling, and the bonding of the halogenated carbazole monomer and the fluorene monomer, and the bonding of the halogenated benzimidazole monomer and the fluorene monomer are respectively completed, thereby obtaining the terpolymer.

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

The reaction time is 20-80 h, preferably 35-65 h, and more preferably 45-55 h.

The copolymerization reaction conditions are mild, the catalytic efficiency is high, the selectivity is high, the byproducts are few, the imidazole structure can be completely retained and cannot be damaged in the reaction process, and the coupling reaction in the invention is not greatly influenced by steric hindrance, so that the monomer containing the halogenated carbazole, the halogenated benzimidazole monomer and the fluorene monomer can smoothly react to complete the ternary copolymerization process.

The molar ratio of the fluorene monomer, the halogenated carbazole monomer and the halogenated benzimidazole monomer is (1.5-3.5): 1:1, preferably (1.8-2.5): 1:1, and more preferably (2.0-2.2): 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 a coupling reaction, compared with the use of the boric acid group, the method is favorable for weakening the boron removal effect in the reaction process and improving the utilization rate of raw materials.

The molar ratio of the fluorene monomer to the catalyst is 1 (0.001-0.2), preferably 1 (0.005-0.1), and more preferably 1 (0.02-0.05). In the reaction in the step 1, the oxidation addition rate of the halogenated carbazole monomer, the halogenated benzimidazole monomer and the zero-valent palladium is a main step influencing the reaction rate, and if the content of the catalyst is too low, the rate of the whole reaction is reduced; if the catalyst content is too large, the reaction rate does not increase beyond 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, and more preferably 0.06mol (6-8) mL.

The concentration of the alkaline substance solution is 1.5-5 mol/L, preferably 2.5-4 mol/L, and more preferably 2.8-3.2 mol/L. Too strong a basicity will cause the halogenated aryl group to self-couple.

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

The reaction is carried out in an inert gas environment, wherein the inert gas is nitrogen or argon, and nitrogen is preferred.

In a preferred embodiment of the invention, halogenated benzimidazole monomers are selected to participate in a 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 selected from phthalic anhydride, naphthalene dicarboxylic anhydride or anthracene dicarboxylic anhydride, and more preferably 2, 3-naphthalene dicarboxylic anhydride.

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

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

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

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

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

The reaction time is 3-18 h, preferably 5-12 h, and more preferably 6-8 h.

And 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 purification.

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

The washing process is to wash the crude product to neutrality with a solvent, which is not able to react with or dissolve the crude product, preferably ethanol or water, more preferably water, such as deionized water, to remove impurity molecules.

And after washing, drying the crude product, preferably performing vacuum drying, wherein the temperature of the vacuum drying is 50-130 ℃, the preferred temperature is 70-100 ℃, the preferred temperature is 80-85 ℃, the time of the vacuum drying is 5-25 h, the preferred time is 8-18 h, the preferred time is 10-15 h, such as 12h, the pressure of the vacuum drying is-80 KPa to-10 KPa, the preferred pressure is-50 KPa to-20 KPa, and the preferred pressure is-30 KPa to-29 KPa.

Preferably, the crude product is purified by extraction, crystallization or column chromatography, preferably by crystallization or column chromatography, more preferably by column chromatography. The solid phase of the column chromatography is silica gel powder, the mobile phase is a mixed solution of dichloromethane and petroleum ether, the volume ratio of the dichloromethane to the petroleum ether is 3:1, and the solvent is removed from the solution by rotary evaporation 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 a precipitating agent to separate the polymer from the solution. The precipitant is selected from alkanes, alcohols, ketones, ethers, and water, preferably selected from hexane, methanol, ethanol, acetone, diethyl ether, petroleum ether, and 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 and the like can be easily wrapped, and in order to ensure the purity and the conductivity of the polymer, the impurity molecules in the polymer need to be removed. After washing, the polymer solution is filtered, preferably with suction, to isolate the polymer product.

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

Preferably, the post-treatment process further comprises purification.

In a preferred mode of the present invention, purification is performed 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 30-150 ℃, preferably 50-120 ℃, and more preferably 60-90 ℃.

The purification time is 24-80 h, preferably 35-70 h, and more preferably 40-55 h.

The terpolymer provided by the invention can be used for manufacturing a semiconductor material of an electric storage device. The fluorene group and the carbazole group rich in electrons are used as excellent electron donor elements, the conjugated polymer introduced with the electron donor group in the main chain of the polymer has a lower HOMO energy level, so that the copolymer has excellent open-circuit voltage, the benzimidazole group is introduced as an excellent electron-deficient receptor element, the conjugated polymer has molecular charge transfer, and the path from benzimidazole to benzisoindolinone is adopted, so that the benzimidazole monomer serves as two different defect subunits to form a donor-acceptor structure terpolymer, the intramolecular charge transfer can be carried out, and the band gap of the conjugated polymer is effectively reduced.

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

An electrical memory device with a terpolymer as the organic layer exhibits ternary Flash-type erasable electrical memory properties. In the ground state, groups in the polymer chain are conceived to be in a random disordered state, charge carrier or hole transition is very difficult, and the electrical memory device is in an OFF state; under the action of an electric field, the charged carbazole group and fluorene group can attract the benzimidazole group to perform conformational ordering to form an ordered configuration, and the ordered configuration reaches an ON1 state; when the electric field intensity is further enhanced, the active charges are subjected to delocalization in a regular conformation and directionally move to the cathode, and finally a high-conductivity channel is formed to reach an ON2 state; when the voltage is turned off, the polymer can remain on as shown in fig. 2.

When an opposite voltage is applied to the electrical storage device, the holes trapped by the traps can be attracted to the interface of the electrode and the polymer again to be recombined with electrons, so that the polymer is restored to the original state, and the purpose of erasing 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 memory device has low starting voltage (NO1 state can reach-0.75V), low energy consumption, prolonged service life, and high switching current ratio (OFF: ON1: ON2 can reach 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, repeated cyclic reading and writing can be carried out, and the performance is excellent.

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

step a, cleaning the substrate layer.

A cathode layer is attached to the substrate layer.

The cathode layer is selected from tin oxide glass (ITO), conductive polymer, graphene or metal with good conductivity, such as Al, Cu and Au, preferably ITO or conductive metal, more preferably ITO or Al. Preferably, the cathode layer is vacuum evaporated on the glass substrate.

And 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, and more preferably, the substrate layer is sequentially cleaned by the sequence of deionized water, absolute ethyl alcohol, acetone, absolute ethyl alcohol and deionized water to remove impurity substances on the substrate. The substrate layer after cleaning is preferably stored in anhydrous 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 and 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 1-30 mg/mL, preferably 3-15 mg/mL, and more preferably 5-12 mg/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, and a uniform organic film is not easily formed, and if the concentration of the polymer solution is too low, the thickness of the formed organic film is thinner, which affects the performance of the electric storage device.

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

The polymer solution may be applied to the cathode layer by 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 spray coating method is uniformly distributed, the production cost is low, and the large-scale production is easy.

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

The thickness of the organic layer 3 is 100 to 300nm, preferably 150 to 280nm, and more preferably 220 to 260 nm. If the organic layer is too thin, the potential barrier is low and electrons are difficult to capture. Too thick an organic layer can result in too high a potential barrier, which can make it difficult for charge carriers to be injected throughout the organic layer, impairing charge transport capability in the 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 120-600 nm, preferably 200-500 nm, and more preferably 250-350 nm.

The area of the anode layer is 0.1-8 mm²Preferably 0.25 to 5mm in thickness²More preferably 0.5 to 3mm²。

The organic layer prepared by the terpolymer provided by the invention has good thermal stability and film forming property, the electric storage device has low starting voltage, high switching current ratio, high resolution ratio and low misreading rate, can quickly respond, can be read and written repeatedly, and has excellent performance. And the synthetic method of the conjugated polymer is simple, the preparation process of the electric storage device is mature, and the industrial production can be realized.

Examples

Example 1

In N₂Under the atmosphere, 1.49g of 2, 3-naphthalic 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 ℃, the solvent is refluxed, and the isothermal reaction is carried out for 6 hours.

After the reaction is finished, the reaction solution is cooled to room temperature, and after a crude product is gradually separated out, the crude product is filtered and washed to be neutral by deionized water. And (3) drying the obtained crude product in a vacuum drying oven at the temperature of 85 ℃ for 12h under the pressure of-30 KPa. And (3) separating and purifying the dried crude product by utilizing column chromatography, wherein the stationary phase of the column chromatography is silica gel powder, and the liquid phase is dichloromethane: petroleum ether (3:1) to obtain the 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-ketone, 0.3mol of 2, 7-dibromo-9- (1-octylnonyl) -9H-carbazole and 0.6mmol of 9, 9-dioctylfluorene-2, 7-diboronic acid di (1, 3-propanediol) ester are added into a reaction vessel, 7mL of toluene and equal volume of 3mol/L potassium carbonate solution are added, and 2 mol% of palladium catalyst Pd (PPh) is added₃)₄The temperature was raised to 108 ℃ with stirring, and the reaction was carried out for 48 hours.

After the reaction, slowly dropping the polymer solution into 200mL of glacial methanol to separate out a product, washing with methanol, performing suction filtration repeatedly for 3 times, and drying the obtained product in a vacuum drying oven at 65 ℃ for 12h under-30 KPa.

And after drying, performing Soxhlet extraction for 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 at the vacuum drying temperature of 60 ℃ for 12 h.

Example 2

And sequentially placing the substrate layer attached with the ITO cathode layer in deionized water, absolute ethyl alcohol, acetone, absolute ethyl alcohol and deionized water for cleaning for 30min respectively, and storing the substrate layer in the 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 cleaned cathode layer, uniformly dispersing the cathode layer 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, the thickness and area of the metal electrode being 300nm and 1.0mm, respectively². A sandwich-structured organic electrical memory device of the Flash memory type is obtained, and a schematic structural diagram is shown in FIG. 1.

Examples of the experiments

Experimental example 1

Hydrogen nuclear magnetic resonance spectroscopy was performed on the terpolymer prepared in example 1 using an INOVA 400MHz high resolution nuclear magnetic resonance spectrometer (TMS as internal standard), CDCl₃As a solvent, the spectrum is shown in FIG. 2.

As can be seen from the figure, the chemical shift delta is the chemical shift of the characteristic peak of the carbazolyl at 4.55ppm, which indicates that the carbazolyl-containing terpolymer is synthesized.¹H-NMR (δ ppm): 8.67-7.06 (aromatic ring characteristic peak), 4.55 (carbazole characteristic peak), 2.41-0.27 (alkyl chain characteristic peak).

Experimental example 2

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

A first voltage sweep is performed on the memory device, with two current increase 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 (ON1 state), a second current increase jump occurs at a voltage of-1.15V, and the electrical memory device transitions from the intermediate conduction state (ON1 state) to a high conduction state (ON2), and then in a second subsequent step of 0V to-6V scanning, the device is always in the high conduction state, indicating that the device can implement ternary storage functionality, and that one write can read multiple times.

The third step scans the memory device in the voltage region of 0V to 6V, and when the voltage is increased to 3.75V, the device is lowered from the high conduction state (ON2) to the low conduction state (OFF) to be restored to the OFF state, at which time the electrical memory device data is erased. The memory device can still keep a stable state after repeated voltage scanning for 200 min. Therefore, the memory device in the illustrated invention is a ternary Flash type memory device.

As can be seen from fig. 4, the maximum switching current ratio of the memory device is: OFF 1 ON2 1:10^1.3:10^4.0The device has high storage density, can accurately control the on and off states, and has low error rate.

The invention has been described in detail with reference to specific embodiments and/or illustrative examples and the accompanying drawings, which, however, should not be construed as limiting the invention. Those skilled in the art will appreciate 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, which 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 said polymer has the following repeating units:

2. The polymer of claim 1, wherein the polymer has the following moiety:

n is an integer of 20 to 300, m is an integer of 20 to 300;

the R is₁、R₂Each independently an alkyl group having 6 to 21 carbon atoms; and/or

The R is₃、R₄Each independently hydrogen, alkyl, aryl or heterocyclic.

3. The terpolymer is characterized by being prepared by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

4. A method of making a terpolymer, comprising the steps of:

5. The method according to claim 4, wherein, in step 1,

the halogenated carbazole monomer is halogenated N-alkyl carbazole, preferably, the 2 and 7 positions of the halogenated carbazole monomer are substituted by halogen; and/or

The halogenated benzimidazole monomer is selected from benzimidazole heterocyclic groups, and halogenated groups are introduced into 4-position and 7-position of benzimidazole in the halogenated benzimidazole monomer; and/or

The fluorene monomer is alkylfluorene, the alkyl is an alkyl containing 3-31 carbon atoms, and preferably, 2 and 7 positions of the fluorene monomer are provided with boronic acid groups or boronic ester groups.

6. The method according to claim 4, wherein in step 1, the halogenated benzimidazole monomer is prepared by the following method:

step 1-1, adding aromatic dicarboxylic anhydride 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, the process is carried out,

the aromatic dicarboxylic anhydride is selected from phthalic anhydride or condensed ring dicarboxylic anhydride, and/or

The halogenated diamine is selected from dihalogenated aryl diamine with two amino groups respectively positioned on two adjacent carbon atoms.

7. The method of claim 6, wherein in step 1-1, the solvent is selected from alkyl carboxylic acids.

8. The method according to claim 6, wherein in the step 1-1, the reaction temperature is 90-120 ℃, and the reaction time is 3-18 h.

9. The method of claim 6, wherein in step 1-2, the post-treatment process comprises cooling, filtering, washing, drying, purifying, and post-purification drying.

10. An electrical storage device, wherein the organic layer of the electrical storage device is prepared from the terpolymer according to any one of claims 1-3 or the terpolymer prepared according to the method of any one of claims 4 to 9.