阅读说明：本技术 芴基三元共聚物/三氧化二铁纳米粒子复合材料、制备方法及其在电存储器件中的用途 (Fluorenyl terpolymer/ferric oxide nanoparticle composite material, preparation method and application thereof in electric storage device ) 是由 常青 王淑红 张洪岩 于 2020-06-24 设计创作，主要内容包括：本发明提供了一种芴基三元共聚物/三氧化二铁纳米粒子复合材料及其制备方法,并且该复合材料可用于制备电存储器件。此电存储器件具备优异的三进制电存储性能,开启电压低,开关电流比高,存储密度大,能够快速响应,可进行多次循环读写,性能优良。芴基三元共聚物/三氧化二铁纳米粒子复合材料的制备方法简单,电存储器件制备工艺稳定,操作简单,在信息存储领域中具有良好的应用前景。(The invention provides a fluorenyl terpolymer/ferric oxide nanoparticle composite material and a preparation method thereof, and the composite material can be used for preparing an electric storage device. The electric storage device has excellent ternary electric storage performance, low starting voltage, high switching current ratio, high storage density, quick response, repeated cyclic reading and writing and excellent performance. The fluorenyl terpolymer/ferric oxide nanoparticle composite material has the advantages of simple preparation method, stable preparation process of the electric storage device, simple operation and good application prospect in the field of information storage.)

1. A fluorenyl terpolymer/ferric oxide nanoparticle composite material is characterized in that the composite material is formed by physically doping a fluorenyl terpolymer and ferric oxide nanoparticles.

2. The composite material according to claim 1, wherein the fluorenyl terpolymer is obtained by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

3. The composite material according to claim 1, wherein the composite material is prepared by the following method:

step 1, adding a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer into a solvent, and heating for reaction to obtain a fluorenyl terpolymer reaction solution;

step 2, carrying out post-treatment on the fluorenyl terpolymer reaction liquid to obtain a fluorenyl terpolymer;

and 3, mixing the fluorenyl terpolymer solution with the ferric oxide nanoparticle dispersion liquid to obtain the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid.

4. The composite material according to claim 1, wherein the iron sesquioxide nanoparticles are prepared by the following method:

step 3-1, adding an iron source into a reaction solvent in the presence of a precipitator, and stirring to obtain a solution to be reacted;

step 3-2, heating the solution to be reacted to obtain a reaction solution;

and 3-3, post-treating the reaction liquid to obtain the ferric oxide nano particles.

5. A preparation method of a fluorenyl terpolymer/ferric oxide nanoparticle composite material is characterized by comprising the following steps:

step 1, adding a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer into a solvent, and heating for reaction to obtain a fluorenyl terpolymer reaction solution;

step 2, carrying out post-treatment on the fluorenyl terpolymer reaction liquid to obtain a fluorenyl terpolymer;

and 3, mixing the fluorenyl terpolymer solution with the ferric oxide nanoparticle dispersion liquid to obtain the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid.

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

the halogenated carbazole monomer is halogenated nitrogen alkyl carbazole monomer,

the halogenated benzimidazole monomer is selected from benzimidazole heterocyclic group monomers,

the fluorene monomer is alkyl fluorene monomer.

7. The method according to claim 5, wherein, in step 3,

the fluorenyl terpolymer solution is obtained by dissolving a fluorenyl terpolymer in a solvent I, wherein the solvent I is 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;

the ferric oxide nano particle dispersion liquid is prepared by dispersing ferric oxide nano particles in a solvent II, wherein the solvent II is selected from sulfones such as dimethyl sulfoxide and dimethyl sulfone, and amides such as N, N-dimethylformamide.

8. The method according to claim 7, wherein, in step 3,

the concentration of the fluorenyl terpolymer solution is 1-20 mg/mL,

the concentration of the ferric oxide nanoparticles in the ferric oxide nanoparticle dispersion liquid is 0.005-0.500 mg/mL.

9. The method according to claim 7 or 8, wherein in the step 3, the volume ratio of the fluorenyl terpolymer solution to the ferric oxide nanoparticle dispersion liquid is 1 (0.5-3).

10. Use of a fluorene-based terpolymer/iron trioxide nanoparticle composite according to any one of claims 1 to 4 for the preparation of an electrical storage device.

Technical Field

The invention belongs to the technical field of storage materials, and particularly relates to a fluorenyl terpolymer/ferric oxide nanoparticle composite material and a synthetic method thereof, in particular to an electric storage device taking the composite material as an active layer and a preparation method thereof.

Background

With the coming of the information age, the amount of information facing the daily life of people increases, and the traditional storage technology is difficult to meet the basic requirement of information storage. Therefore, higher performance electrical storage is indispensable. 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.

To date, various materials have been developed for use in electrical memory devices, such as inorganic nanomaterials, organic small molecules, polymers, and the like. Among them, the polymer used as an active layer for preparing a memory device can further reduce the size of the device, but it is difficult to obtain the precise molecular weight and molecular weight distribution of the polymer, and thus, the repeatability and stability of the memory layer prepared therefrom are to be further improved. In addition, there are many reports related to different types of inorganic nanoparticles in the field of information storage. Compared with the conventional material, the inorganic nano material has unique physical and chemical properties and shows superiority in the application of a memory device, but the inorganic nano material is not easy to disperse and easy to aggregate, and the problems of poor performance repeatability and stability of an active layer are also caused.

Therefore, it is necessary to develop a material for preparing a storage layer of a memory device, which has good repeatability and stability, and can prepare a memory device with high storage speed, high capacity, low energy consumption and good comprehensive performance.

Disclosure of Invention

In order to solve the above problems, the inventors have studied and found a composite material of a fluorene-based terpolymer and ferric oxide nanoparticles, wherein the ferric oxide nanoparticles in the composite material are uniformly distributed, so that the capture and transmission of carriers in the composite material can be enhanced, and the stability of a memory device can be effectively improved. The composite material has simple synthesis method and easy processing into a film, and the prepared electric storage device has ternary electric storage performance under the external voltage. The flourenyl terpolymer and the ferric oxide nanoparticles have synergistic effect, the storage performance of the device is improved, the starting voltage is further reduced, the switching current ratio is effectively improved, the comprehensive performance is good, the preparation process is simple, and the cost is low, so that the preparation method is completed.

The invention aims to provide a fluorenyl terpolymer/ferric oxide nanoparticle composite material which is formed by physically doping a fluorenyl terpolymer and ferric oxide nanoparticles.

The fluorenyl terpolymer is obtained by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

The fluorene-based terpolymer is a carbazole-fluorene-benzimidazole terpolymer having the following repeating units:

wherein R is₁、R₂Each independently an alkyl group having 3 to 31 carbon atoms.

The fluorene-based terpolymer has the following structural moiety:

wherein m is an integer of 20 to 300, and n is an integer of 20 to 300.

The fluorenyl terpolymer/ferric oxide nanoparticle composite material is prepared by the following method:

step 1, adding a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer into a solvent, and heating for reaction to obtain a fluorenyl terpolymer reaction solution;

step 2, carrying out post-treatment on the fluorenyl terpolymer reaction liquid to obtain a fluorenyl terpolymer;

and 3, mixing the fluorenyl terpolymer solution with the ferric oxide nanoparticle dispersion liquid to obtain the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid.

The invention also aims to provide a preparation method of the fluorenyl terpolymer/ferric oxide nanoparticle composite material, which comprises the following steps:

step 1, adding a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer into a solvent, and heating for reaction to obtain a fluorenyl terpolymer reaction solution;

step 2, carrying out post-treatment on the fluorenyl terpolymer reaction liquid to obtain a fluorenyl terpolymer;

and 3, mixing the fluorenyl terpolymer solution with the ferric oxide nanoparticle dispersion liquid to obtain the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid.

The invention also aims to provide application of the fluorenyl terpolymer/ferric oxide nanoparticle composite material to preparation of an electric storage device.

The invention also provides an electric storage device taking the fluorenyl terpolymer/ferric oxide nanoparticle composite material as an active 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 with a cathode layer;

b, attaching the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid to a cathode layer to form an active layer;

and c, attaching an anode layer on the active layer to obtain the electric storage device.

The invention has the following beneficial effects:

(1) 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.

(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. 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.

(3) The doped inorganic nano particles can enhance the transmission and capture of carriers and improve the repeatability and stability of the performance of the active layer of the composite material.

(4) The electric storage device prepared from the fluorenyl terpolymer/ferric oxide nanoparticle composite material has the advantages of low starting voltage, low energy consumption, high on-off current ratio, high resolution, low misreading rate, quick response, capability of performing repeated cyclic reading and writing and good stability improvement.

(5) The fluorenyl ternary copolymer/nano composite material has simple synthesis method, the preparation process of the electric storage device is easy to realize, and the 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 spectrum of a fluorene-based terpolymer in example 1 of the present invention;

FIG. 3 shows an X-ray diffraction pattern of iron sesquioxide nanoparticles in example 2 of the present invention;

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

Detailed Description

The technical solution of the present invention is not limited to the following exemplary embodiments, but includes any combination of the respective embodiments.

The fluorenyl terpolymer and the ferric oxide nanoparticles are utilized to form the composite material, wherein the ferric oxide nanoparticles are uniformly distributed, so that the capture and transmission of current carriers in the composite material can be enhanced, and the stability of an active layer in a memory device is effectively improved.

The fluorenyl terpolymer/ferric oxide nanoparticle composite material is formed by physically doping the fluorenyl terpolymer and the ferric oxide nanoparticles.

The fluorenyl terpolymer is a carbazole-fluorene-benzimidazole terpolymer and is obtained by polymerizing a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer.

The preparation method of the fluorenyl terpolymer comprises the following steps:

step 1, adding a halogenated carbazole monomer, a halogenated benzimidazole monomer and a fluorene monomer into a solvent, and heating for reaction to obtain a fluorenyl terpolymer reaction solution.

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

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 group monomers, the heterocyclic group is selected from thiophene group, thiazole group, furan group, pyridine group, pyrrole group, quinoline group, isoquinoline group, acridine group, indole group, preferably selected from benzimidazole isoindoline group or benzimidazole isoindoline group, and more preferably is benzimidazole and benzisoquinoline group.

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 an alkyl fluorene monomer, wherein the alkyl is an alkyl group having 3-31 carbon atoms, preferably an alkyl group having 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 a boronic acid group or a boronic ester group at the 2 and 7 positions, such as an alkyl boronic acid group, an aryl boronic acid group, an alkenyl boronic acid group, an alkyl boronic ester group, an aryl boronic ester group or an alkenyl boronic ester group, preferably an alkyl boronic ester group, an aryl boronic ester group or an alkenyl boronic ester group, more preferably an alkyl boronic ester group, 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 fluorenyl terpolymer is easy to process, low in cost and excellent in electrical property.

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. tetrakis (triphenylarsine) palladium (Pd (AsPh)₃)₄) Tetrakis (tri (n-butylphosphino) palladium (Pd (n-Bu)₃P)₄) Tetrakis (trimethoxy phosphonium) palladium Pd ((MeO)₃P)₄Tetrakis (triphenylphosphine) palladium (Pd (PPh)₃)₄) Preferably a palladium salt or a palladium complex, more preferably a palladium complex, such as tetrakis (triphenylphosphine) palladium (Pd (PPh)₃)₄)。

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.

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.

In the invention, 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 carbazoles, the halogenated benzimidazoles 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 reaction 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 reaction rate 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 the invention, the preparation method of the halogenated benzimidazole monomer comprises the following steps:

step 1-1, adding 2, 3-naphthalic anhydride and halogenated diamine into a solvent, and heating for reaction to obtain a reaction solution.

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, 2, 3-naphthalic anhydride is reacted with halogenated diamine to obtain a benzimidazole structure. Imidazole is a five-membered heterocyclic compound containing two nitrogen atoms, and imidazole rings have a coplanar structure, wherein carbon atoms and nitrogen atoms on the imidazole rings are in 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 molar ratio of the 2, 3-naphthalic 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 2, 3-naphthalic anhydride 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.

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

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, and the pressure of the vacuum drying is-80 to-10 kPa, the preferred pressure is-50 to-20 kPa, and the preferred pressure is-30 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.

And 2, carrying out post-treatment on the fluorenyl terpolymer reaction liquid to obtain the fluorenyl terpolymer.

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

And the crystallization is to add the fluorenyl terpolymer reaction liquid into a crystallization solvent to separate the fluorenyl terpolymer from the solution. The crystallization solvent is selected from alkanes, alcohols, ketones, ethers and water, preferably selected from hexane, methanol, ethanol, acetone, diethyl ether, petroleum ether and water, and more preferably selected from methanol or acetone. Preferably, the precipitation of the fluorene-based terpolymer is more easily promoted during the crystallization process using an ice solvent.

The washing is carried out on the fluorenyl terpolymer by using a crystallization solvent. The fluorenyl terpolymer is a long-chain molecule and is easy to wrap micromolecules and other impurity molecules, and in order to ensure the purity and the conductivity of the fluorenyl terpolymer, the impurity molecules in the fluorenyl terpolymer need to be removed. After washing, the fluorene-based terpolymer product is isolated by filtration, preferably suction filtration.

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 the vacuum drying is-80 to-10 kPa, preferably-50 to-20 kPa, and more preferably-35 to-25 kPa. The fluorene-based terpolymer has long molecular chain, is easy to twine, has strong adsorption or occlusion effect on a solvent, and is difficult to dry. The invention adopts high vacuum degree, and can achieve good effect of removing the crystallization solvent by matching with the selection of the crystallization solvent.

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 preferably acetone.

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.

After the purification, performing vacuum drying on the product, wherein the drying temperature is 30-120 ℃, preferably 50-90 ℃, and more preferably 55-65 ℃; the vacuum drying time is 5-25 h, preferably 8-18 h, more preferably 10-15 h, such as 12 h; the pressure of the vacuum drying is-80 to-10 kPa, preferably-50 to-20 kPa, and more preferably-35 to-25 kPa.

The fluorene-based terpolymer of the present invention has the following repeating units:

wherein R is₁、R₂Each independently an alkyl group having 3 to 31 carbon atoms.

In the present invention, the fluorene-based 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;

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.

And 3, mixing the fluorenyl terpolymer solution with the ferric oxide nanoparticle dispersion liquid to obtain the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid.

The fluorenyl terpolymer solution is obtained by dissolving a fluorenyl terpolymer in a solvent I. The solvent I is 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. The concentration of the fluorenyl terpolymer solution is 1-20 mg/mL, preferably 2-15 mg/mL, and more preferably 3-10 mg/mL.

The ferric oxide nano particle dispersion liquid is prepared by dispersing ferric oxide nano particles in a solvent II. The solvent II is selected from sulfones, such as dimethyl sulfoxide and dimethyl sulfone, amides, such as N, N-dimethylformamide, preferably amide solvents, more preferably N, N-dimethylformamide. Through multiple tests, the selected solvent II can keep the ferric oxide nanoparticles in a good dispersion state, the dispersibility difference of the nanoparticles in different solvents is large, and if the dispersibility is not good, the uniformity of an active layer in a device can be directly influenced. The solvent I and the solvent II used in the step 3 of the invention can well dissolve and disperse the fluorenyl terpolymer and the ferric oxide nanoparticles respectively and are easy to remove.

The concentration of the ferric oxide nanoparticle dispersion liquid is 0.005-0.500 mg/mL, preferably 0.050-0.200 mg/mL, more preferably 0.100-0.130 mg/mL, such as 0.125 mg/mL.

The volume ratio of the fluorenyl terpolymer solution to the ferric oxide nanoparticle dispersion liquid is 1 (0.5-3), preferably 1 (1-2), and more preferably 1: 1.

The ferric oxide nano particles are prepared by the following method:

and 3-1, adding an iron source into the reaction solvent in the presence of a precipitator, and stirring to obtain a solution to be reacted.

The iron source is selected from ferric chloride or ferric nitrate, preferably ferric nitrate is used.

The precipitant is selected from organic amines such as urea or hexamethylenetetramine, carbonates such as ammonium carbonate, sodium carbonate or potassium carbonate, preferably from urea, hexamethylenetetramine, ammonium carbonate, sodium carbonate or potassium carbonate, more preferably from urea, hexamethylenetetramine or ammonium carbonate, such as urea. The precipitator used in the invention can control the growth speed of the ferric oxide nano particles, further control the particle size and keep the uniformity of the particle size.

The reaction solvent is water, preferably, the reaction solvent is a mixed solvent of water and an alcohol solvent, wherein the alcohol solvent is selected from methanol, ethanol, ethylene glycol or propanol, preferably ethanol or ethylene glycol, and more preferably ethanol.

Adding a surfactant selected from one or more of quaternary ammonium salt surfactants, sulfate ester surfactants or alcohol amine surfactants, preferably one or more selected from cetyl trimethyl ammonium bromide, sodium dodecyl sulfate or ethanolamine, more preferably sodium dodecyl sulfate and/or ethanolamine into the solution to be reacted.

Preferably, a soluble nitrate such as sodium nitrate is added to the solution to be reacted, so that the solubility of the reaction system can be improved and the particle size of the iron sesquioxide nanoparticles can be prevented from being too large.

In a preferred mode of the present invention, an amide-based solvent, preferably selected from N, N-dimethylformamide or N, N-dimethylacetamide, more preferably N, N-dimethylformamide, is added to the solution to be reacted. The addition of the amide solvent is beneficial to adjusting and controlling the particle size and the crystal form of the ferric oxide nano particles and improving the conductivity of the ferric oxide nano particles.

In a preferred mode of the invention, the iron source and the precipitant are added into the solvent to be dissolved, then the surfactant and the soluble nitrate are added, after the substances are stirred and dissolved, the amide solvent is added dropwise to obtain a mixed solution, and preferably, the mixed solution is subjected to ultrasonic treatment to obtain a solution to be reacted.

The molar ratio of the iron element in the iron source to the precipitator is 1 (4-12), preferably 1 (6-10), and more preferably 1 (8-9).

The molar volume ratio of the iron element in the iron source to the reaction solvent is (0.001-0.012) mol:30mL, preferably (0.002-0.008) mol:30mL, and more preferably (0.003-0.004) mol:30 mL. In a preferred embodiment of the present invention, the reaction solvent is a mixed solvent of water and ethanol, and the volume ratio of the water to the alcohol solvent is 20 (5-15), preferably 20 (7-12), and more preferably 20 (8-10).

The mass molar ratio of the surfactant to the iron element in the iron source is 1.50 (0.001-0.010), preferably 1.50 (0.002-0.006), and more preferably 1.50 (0.003-0.004). In a preferred embodiment of the present invention, sodium dodecyl sulfate and ethanolamine are used as the surfactant at the same time, and the mass ratio of the sodium dodecyl sulfate to the ethanolamine is (0.6-1.5), preferably (0.8-1.2): 0.5, and more preferably (0.9-1.05): 0.5.

The mass mol ratio of the soluble nitrate to the iron element in the iron source is 0.5g (0.001-0.010) mol, preferably 0.5g (0.002-0.006) mol, more preferably 0.5g (0.003-0.004) mol.

The volume ratio of the amide solvent to the reaction solvent is (2.5-7.5): 30, preferably (3.5-6.5): 30, and more preferably (4-6): 30.

And 3-2, heating the solution to be reacted to obtain a reaction solution.

Preferably, the solution to be reacted is heated in a high pressure reaction kettle for reaction, and a reaction solution is obtained after the reaction is finished. The reaction temperature is 105-135 ℃, preferably 110-130 ℃, more preferably 115-125 ℃, such as 120 ℃. The reaction time is 12 to 28 hours, preferably 15 to 25 hours, more preferably 18 to 22 hours, such as 20 hours.

And 3-3, post-treating the reaction liquid to obtain the ferric oxide nano particles.

The post-treatment comprises washing and drying.

The washing is carried out by sequentially using deionized water and ethanol, and the washing times are 3-7 times. After washing, solid ferric oxide nano particles are separated out by centrifugation and dried. The drying mode is preferably vacuum drying, the vacuum drying temperature is 40-60 ℃, such as 50 ℃, and the drying time is 4-8 hours, such as 6 hours.

The ferric oxide nanoparticles prepared by the method have low energy band structure, strong transmission and capture capacity to current carriers, are not easy to agglomerate, and can be well applied to fluorenyl terpolymer.

And (3) preparing an active layer of the electric storage device by using the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid obtained in the step 3.

The fluorenyl terpolymer/ferric oxide nanoparticle composite material provided by the invention can be used for manufacturing an active layer of an electric storage device. The fluorenyl terpolymer has excellent ternary electrical storage characteristics, the ferric oxide nanoparticles have the most stable property in iron oxide, have a corundum structure, are rich in natural reserve, corrosion-resistant and environment-friendly, have a lower energy band structure (2.1eV), and can enhance the transmission and capture of carriers and improve the storage performance and stability of a device when doped into the fluorenyl terpolymer.

In the invention, the fluorenyl terpolymer/ferric oxide nanoparticle composite material is used as an active layer to prepare the electric storage device. The electrical storage device includes a substrate layer, a cathode layer, an active layer, and an anode layer, as shown in fig. 1.

The electrical storage device with the fluorenyl terpolymer/ferric oxide nanoparticle composite material as the active layer shows ternary Flash type nonvolatile electrical storage performance. In the ground state, it is difficult to obtain sufficient energy for carriers to pass through and inject into the barrier, and the electric memory device is in the OFF state; when the electric charge obtains enough energy under the action of the electric field, the electric charge is filled into the structural trap, and the device reaches an ON1 state; when the electric field intensity is further increased, the conductive material is accumulated from the cathode layer side to the anode layer side, and when the bias voltage reaches a second threshold voltage (V)_th2) When the conductive filament successfully connects the top and bottom electrodes, the conductivity of the device transitions to the ON2 state, the device remains in the ON2 state until a reverse voltage is applied to the device, and carriers pass through at low voltageThe conduction path and the conductive filament are smoothly transported, and as the voltage continues to rise, resulting in an excess of carriers, a large amount of joule heating is generated to cause the conductive filament to break, and the device switches from the ON2 state back to the OFF state, as shown in fig. 4.

The active layer prepared by the fluorenyl terpolymer/ferric oxide nanoparticle composite material has good thermal stability and film-forming property. The prepared electric memory device has low starting voltage (NO1 state can reach-0.50V), low energy consumption, prolonged service life, and high switching current ratio (OFF: ON1: ON2 can reach 1: 10)^2.0:10^5.1) The memory has high storage density, high resolution, low error reading rate, quick response, repeated cyclic reading and writing and excellent performance.

In the invention, the preparation method of the memory device comprises the following steps:

step a, cleaning the substrate layer with the cathode 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 and acetone, preferably one or more of deionized water, absolute ethyl alcohol and acetone, and more preferably, the substrate layer is sequentially cleaned by the deionized water, the acetone and the absolute ethyl alcohol in sequence to remove impurity substances on the substrate. The substrate layer after cleaning is preferably stored in anhydrous ethanol.

And b, attaching the fluorenyl terpolymer/ferric oxide nanoparticle composite dispersion liquid to a cathode layer to form an active layer.

The composite dispersion may be applied to the cathode layer by a film forming method such as spin coating, spray coating, dip coating, roll coating or ink injection printing, preferably spin coating, roll coating or spray coating, more preferably spin coating. The active layer obtained by the spin coating method is uniform in distribution, low in production cost and easy for large-scale production.

The coated active 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 5-30 h, preferably 8-20 h, and more preferably 10-15 h; the pressure of the vacuum drying is-80 to-10 kPa, preferably-50 to-20 kPa, and more preferably-35 to-25 kPa.

The thickness of the active layer is 100-300 nm, preferably 150-280 nm, and more preferably 220-260 nm. If the active layer is too thick, the potential barrier is too high, charge carriers are difficult to inject into the whole active layer, and the charge transport capability in the thin film is weakened. Too thin an active layer results in a low barrier and difficult electron capture.

And c, attaching an anode layer on the active layer to obtain the electric storage device.

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 120-500 nm, preferably 200-400 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 fluorenyl terpolymer/ferric oxide nanoparticle composite material provided by the invention has good film forming property and thermal stability, and the repeatability and stability of an active layer prepared from the fluorenyl terpolymer/ferric oxide nanoparticle composite material are good. The performance of the electric storage device such as the turn-on voltage, the switching current ratio and the like is improved, the misreading rate is low, the stability is high, the quick response can be realized, the repeated cyclic reading and writing can be carried out, and the comprehensive performance is excellent. The preparation method of the composite material is simple, the preparation process of the electric storage device is mature, and industrial production can be realized.