CN115915775A - A memristor based on a covalent organic framework (COF) film and its preparation method - Google Patents

Abstract

The invention discloses a memristor based on a covalent organic frame film, whose structure from bottom to top is: a substrate, a conductive bottom electrode, a covalent organic frame film, an organic polymer film and a conductive top electrode. The preparation of the memristor includes the following steps: at 0-80°C, mix a specific aromatic dialdehyde mixed solution and an aromatic polyamine mixed solution, drop it on the desired conductive bottom electrode or directly place the substrate with the conductive bottom electrode By immersing the bottom electrode in the mixed solution, a uniform covalent organic framework film can be obtained on the bottom electrode for the memristor. Then a polymer colloid solution is prepared, which is spin-coated on the surface of the covalent organic framework film, and finally the top electrode is prepared by thermal evaporation or sputtering using a mask. The present invention proposes a new type of memristor preparation method for the first time. The preparation method is simple in process, economical in price, does not require high-precision precision instruments, and can grow large-area memristors in situ on a substrate without complicated environments. Covalent organic framework (COF) films.

Description

A memristor based on a covalent organic framework (COF) film and its preparation method

technical field

The invention belongs to the technical field of application of organic two-dimensional materials, and in particular relates to a memristor based on a covalent organic framework (COF) film and a preparation method thereof.

Background technique

As an emerging class of porous materials, covalent organic frameworks (COF) materials have attracted much attention due to their interesting structural advantages such as total organic framework, tunable porosity, and predictable structure. However, the insolubility and non-processability of covalent organic framework powders limit their applications. At present, covalent organic framework materials have been widely studied in the fields of gas storage and separation, heterogeneous catalysis, energy storage materials, optoelectronics, sensing, and drug delivery, and have shown excellent application prospects. Previously, some researchers have used covalent organic framework materials to make usable memristors.

However, the synthesis methods of most COFs are cumbersome and the reaction time is long. Generally, they are synthesized by solvothermal method and need to be reacted for several days under high temperature and high pressure environment. For example, the article Towards High-Performance Resistive Switching Behavior through Embedding D-A System into 2D Imine-Linked The COF-TT-BT and COF-TT-TVT films synthesized by Covalent OrganicFrameworks need to be reacted at 120°C for 72h. Moreover, many memristors prepared using covalent organic frameworks are not grown by in-situ synthesis, and need to be transferred (for example, patent CN2018102788065), which will make the preparation process cumbersome. In addition, many memristors prepared using covalent organic frameworks have a three-layer structure (bottom electrode-film-top electrode) without a barrier layer. The top electrode is generally prepared by thermal evaporation or sputtering, while the organic The covalent frame film is an ordered structure with one-dimensional channels, which has a large pore structure. Direct evaporation or sputtering on the surface of the film can easily cause the metal to invade the interior of the film, which is equivalent to reducing the thickness of the film and improving the efficiency of the film. The contingency of device fabrication is eliminated.

Based on the above reasons, this application is filed.

Contents of the invention

Based on the above reasons, in view of the problems or defects in the prior art, the object of the present invention is to provide a memristor based on a covalent organic framework (COF) film and its preparation method, which solves or at least partially solves the existing problems in the prior art. The above-mentioned technical defect of existence. The covalent organic framework (COF) of the present invention can grow rapidly in situ on various flat substrate surfaces in the atmosphere and in a wide temperature range, and can be grown by changing the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution Films with different thicknesses can be obtained by changing the concentration, molar mass and reaction time, which is convenient for making memristors with different thickness structures.

In order to realize above-mentioned first object of the present invention, the technical scheme that the present invention adopts is as follows:

A memristor based on a covalent organic framework (COF) film, which sequentially includes a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer, and a conductive top electrode from bottom to top.

Further, in the above technical solution, the thickness of the covalent organic framework film is 100-150 nm, and the thickness of the organic polymer barrier layer is 60-200 nm.

Further, in the above technical solution, the thickness of the conductive bottom electrode is 60-200 nm, the thickness of the conductive top electrode is 50-200 nm, and the thickness of the conductive top electrode is preferably 60-100 nm.

Further, in the above technical solution, the substrate is any one of glass, silicon wafer with an oxide layer (SiO ₂ ), polyethylene terephthalate (PET), and the like.

Further, in the above technical solution, the conductive bottom electrode is any one of ITO, FTO, gold or platinum.

Further, in the above technical solution, the conductive top electrode is any one of aluminum, gold, platinum, titanium, tungsten, niobium, nickel, cobalt, copper, silver, or graphene.

Further, in the above technical solution, the covalent organic framework film is prepared by the following method: in an atmospheric environment at 0-80°C, mix the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution, and quickly mix the obtained Droplets are added to the surface of the conductive bottom electrode or the substrate with the conductive bottom electrode is directly immersed in the mixed liquid, so that a layer of uniform covalent organic framework film can be obtained on the substrate surface.

Further, the covalent organic framework film described above is prepared by in-situ growth, and the specific operation steps are as follows:

Mix the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution evenly according to the ratio, then take 50-300 μL dropwise with a pipette gun on the surface of the substrate with a conductive bottom electrode, wait for 2-15 minutes, or put the conductive bottom electrode The substrate is directly immersed in the uniformly mixed solution for 2-15 minutes, then the substrate is taken out, washed with organic solvent D to remove excess reactants, and finally dried at room temperature.

Preferably, in the above technical solution, the ratio of the amounts of aromatic dialdehydes and aromatic polyamines in the aromatic dialdehyde mixed solution to the aromatic polyamine mixed solution is: (0.00002755-0.00005964):0.00002755.

Preferably, in the above technical solution, the volume ratio of the aromatic dialdehyde mixed solution to the aromatic polyamine mixed solution is 1:1.

Preferably, in the above technical solution, the organic solvent D is any one of ethanol, isopropanol or methylene chloride.

Preferably, in the above technical scheme, the aromatic dialdehyde mixed solution is prepared by the following method: weigh the aromatic dialdehyde according to the proportion, then add organic solvent A, organic solvent B and organic acid C in sequence, fully dissolve, and obtain transparent A colorless aromatic dialdehyde mixed solution, wherein the aromatic dialdehyde concentration in the aromatic dialdehyde mixed solution is 0.00626-0.01355 mol/L, and the volume ratio of the organic acid is 5%-10%.

Preferably, in the above technical scheme, the aromatic polyamine mixed solution is prepared by the following method: weigh the aromatic polyamine according to the proportion, then add organic solvent A, organic solvent B and organic acid C in sequence, fully dissolve, and obtain deep A green aromatic polyamine mixed solution, wherein the concentration of the aromatic polyamine in the aromatic polyamine mixed solution is 0.00626 mol/L, and the volume ratio of the organic acid is 5%-10%.

More preferably, in the above technical solution, the aromatic dialdehyde is any one of terephthalaldehyde, isophthalaldehyde or biphenyldialdehyde.

More preferably, in the above technical solution, the aromatic polyamine is tris(4-aminophenyl)amine (TAPA).

More preferably, in the above technical scheme, the organic solvent A is ethanol or isopropanol.

More preferably, in the above technical solution, the organic solvent B is mesitylene.

More preferably, in the above technical solution, the organic acid C is acetic acid or succinic acid.

Further, in the above technical solution, the organic polymer barrier layer is prepared by the following method:

The organic polymer A is dissolved in the liquid B at 80-100° C. to obtain a colloidal solution, and the colloidal solution is spin-coated on the surface of the covalent organic framework film by a spin coating method.

More preferably, in the above technical solution, the organic polymer A is polyvinyl alcohol (PVA) or polymethyl methacrylate (PMMA).

More preferably, in the above technical scheme, the liquid B is any one of deionized water, dichloromethane, dimethyl sulfoxide, dichloroethane, chloroform, acetone, methyl ethyl ketone, benzene, chlorobenzene or tetrahydrofuran, etc. A sort of. It should be noted that since PVA is almost insoluble in organic solvents, when the organic polymer A is polyvinyl alcohol (PVA), the corresponding liquid B must be deionized water.

More preferably, in the above technical solution, the mass volume ratio of the polymer A to the liquid B in the colloidal solution (polymer mass: liquid volume) is 1-20 mg/mL.

The second object of the present invention is to provide a method for preparing the above-mentioned memristor based on a covalent organic framework (COF) film, and the method specifically includes the following steps:

(1) The substrate with the conductive bottom electrode is cleaned, then dried;

(2) growing a covalent organic framework film on the surface of the clean and dry bottom electrode, and then drying;

(3) Spin coating a colloidal solution on the covalent organic framework film to obtain an organic polymer barrier layer;

(4) Prepare a conductive top electrode on the surface of the organic polymer barrier layer by means of thermal evaporation or magnetron sputtering.

Compared with the prior art, the present invention has the advantages of:

(1) The present invention can rapidly (about 10 minutes) in-situ grow various flat substrate surfaces in a wide temperature range, and the preparation method is simple, does not involve sophisticated and expensive instruments, and the medicines used in the present invention are all It is a medicine that can be mass-produced in factories, and the price is economical.

(2) The memristor in the present invention consists of a five-layer structure, which are substrate, conductive bottom electrode, covalent organic framework film, organic barrier layer and conductive top electrode from bottom to top. The substrate and the conductive bottom electrode can be regarded as one part, for example, it can be a glass sheet with ITO or a silicon sheet with a metal film, which only plays a supporting and conductive role, so its thickness has no obvious impact on the performance of the device; The covalent organic framework film is the core structure, which is the core of memristor resistance change. The thickness of about 100nm has the best performance and the most stable. If it is too thin, it is easy to break down and become a conductor. It plays the role of preventing the intrusion of the metal top electrode, which is also the difference between the present invention and many other inventions. The top electrode of the present invention is prepared by sputtering or thermal evaporation. If there is no barrier layer, the metal will randomly enter the inside of the film, which greatly improves the contingency of device preparation and reduces the stability of the device; both the conductive top electrode and the bottom electrode are However, the thickness of the top electrode is 60-100nm. If it is too thin, it is easy to be pierced by the test needle during the test and cannot be tested. If it is too thick, it will need to increase the time of sputtering or thermal evaporation, which may affect the film. damage and increase costs.

Description of drawings

Fig. 1 is the structural representation of the memristor based on covalent organic framework (COF) film of the present invention;

Fig. 2 is the switching characteristic curve of the memristor prepared in embodiment 1;

Fig. 3 is the cycle stability test result of the memristor prepared in embodiment 1;

Fig. 4 is the switching characteristic curve of the memristor prepared in embodiment 2;

Fig. 5 is the cycle stability test result of the memristor prepared in embodiment 2;

Fig. 6 is the switching characteristic curve of the memristor prepared in embodiment 3;

Fig. 7 is the cycle stability test result of the memristor prepared in embodiment 3;

Fig. 8 is the switching characteristic curve of the memristor prepared in embodiment 4;

Fig. 9 is the cycle stability test result of the memristor prepared in embodiment 4;

Figure 10 is a scanning electron microscope image of the covalent organic framework film prepared in Example 2;

FIG. 11 is a scanning electron microscope image of the covalent organic framework film prepared in Example 4.

Detailed ways

The present invention will be described in further detail below through examples of implementation.

In order to better understand the present invention but not to limit the scope of the present invention, all figures representing dosage, percentage, and other numerical values used in this application should be understood as being modified by the word "about" in all cases. Accordingly, unless otherwise indicated, the numerical parameters set forth in the specification are approximations that may vary depending upon different properties sought to be obtained. At a minimum, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

The invention provides a memristor based on a covalent organic frame film, which has a structure from bottom to top: a substrate, a conductive bottom electrode, a covalent organic frame film, an organic polymer film and a conductive top electrode. The preparation of the memristor includes the following steps: at 0-80°C, mix a specific aromatic dialdehyde mixed solution and an aromatic polyamine mixed solution, drop it on the desired conductive bottom electrode or directly put the substrate with the conductive bottom electrode By immersing the bottom electrode in the mixed solution, a uniform covalent organic framework film can be obtained on the bottom electrode for the memristor. Then a polymer colloid solution is prepared, which is spin-coated on the surface of the covalent organic framework film, and finally the top electrode is prepared by thermal evaporation or sputtering using a mask. The present invention proposes a new type of memristor preparation method for the first time. The preparation method is simple in process, economical in price, does not require high-precision precision instruments, and can grow large-area memristors in situ on a substrate without complicated environments. Covalent organic framework (COF) films.

In the specific embodiment of the present invention, involved instrument is as follows:

Ultrasonic cleaner

Spin coater

Thermal evaporation coater

Agilent Technologies B1500A Semiconductor Device Analyzer and Probe Station

scanning electron microscope

The drug purchase sources involved are:

Aromatic dialdehydes and aromatic polyamines were purchased from Shanghai Yuanye Biotechnology Co., Ltd., and other reagents were purchased from Sinopharm Group, and the purity was analytically pure.

Description of test method:

Switching characteristic curve: use Agilent Techolodies B1500A semiconductor device analyzer and probe station to test, apply voltage on the conductive top electrode, and ground the conductive bottom electrode. The test voltage application method is 0V→negative cut-off voltage→0V→positive cut-off voltage→0V , corresponding to the test results, taking Figure 2 as an example, 0V→negative cut-off voltage corresponds to 1 in the figure, negative cut-off voltage→0V corresponds to 2 in the figure, 0V→positive cut-off voltage corresponds to 3 in the figure, positive cut-off voltage→0V Corresponding to 4 in the figure. The step size in the process of positive voltage scanning (ie 0V→positive cut-off voltage→0V) is positive cut-off voltage/100, and the step size in the process of negative voltage scan (ie 0V→negative cut-off voltage→0V) is negative cut-off voltage/100.

Cyclic stability test: repeat the switching characteristic test, a switching characteristic curve (i.e. voltage 0V → negative cut-off voltage → 0V → positive cut-off voltage → 0V scan) is regarded as a cycle, using the cycle test function that comes with the semiconductor analyzer The test repeats the switching characteristic test, and then selects two resistance values at a certain voltage point in all cycles according to the performance of different devices for drawing. Taking Example 1 as an example, select the resistance values of the two points of the high-resistance state and the low-resistance state at 0.25V, and take the resistance value at 0.25V for all cycles, and then draw the graph to obtain the cycle stability test scatterplot.

Example 1

A memristor based on a covalent organic framework (COF) film in this embodiment includes a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer, and a conductive top electrode from bottom to top; wherein: The thicknesses of the substrate, conductive bottom electrode, covalent organic framework film, organic polymer barrier layer and conductive top electrode are 1 cm, 100 nm, 150 nm, 50 nm and 60 nm in sequence.

The above-mentioned memristor based on covalent organic framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Clean the 2cm×2cm×1cm ITO glass, put it on the glass cleaning rack, immerse it in ultrapure water for ultrasonic cleaning for 30 minutes, then replace it with acetone for ultrasonic cleaning for 30 minutes, and finally replace it with absolute ethanol for 30 minutes , and finally take it out and dry it in a drying oven at 60°C for 6 hours.

(2) Weigh 8 mg of terephthalaldehyde in a small weighing bottle, successively add 2 ml of absolute ethanol, 2 ml of mesitylene and 400 μL of acetic acid; weigh 8 mg of tris( 4-Aminophenyl) amine (TAPA), add 2ml of ethanol, 2ml of mesitylene and 400μL of acetic acid, after it is fully dissolved, mix the two bottles of solution evenly; take 200μL dropwise on the surface of ITO placed horizontally, After reacting for 10 minutes, rinse the unreacted solution with ethanol, and dry at room temperature for 12 hours to obtain a covalent organic framework film; wherein:

The ratio of the amount of terephthalaldehyde to TAPA in the terephthalaldehyde mixed solution and the TAPA mixed solution is 0.00005964:0.00002755.

(3) Preparation of PVA colloidal liquid: take 0.2g polyvinyl alcohol (PVA) (molecular weight is 1750 ± 50) and dissolve in 10ml ultrapure water at 90°C to obtain a colloidal solution; take 40 μL of the colloidal solution for spin coating On the surface of the covalent organic framework film, the spin coating parameter is 3000rmp, and the spin coating time is 20s to obtain an organic polymer barrier layer.

(4) Evaporate an Al electrode on the surface of the organic polymer barrier layer with a mask.

The I-V characteristics of the covalent organic framework (COF) film-based memristor device prepared in this example were tested with a semiconductor device analyzer.

Fig. 2 is the switching characteristic curve of the memristor prepared in Example 1, and the direction of the change of the curve is shown by the arrow, and the initial resistance state of the memristor is a high resistance state. Unlike many memristors, the memristor The device requires a negative scan voltage to bring it into a low-impedance state. As shown in Figure 2, start scanning with a voltage of 0V→-1.5V→0V, limit the current to A, and when the voltage is -0.25V, the memristor will be converted from a high-impedance state to a low-impedance state. Afterwards, the voltage of 0V→1V→0V is scanned, and when the voltage is 0.7V, the memristor will be converted from a low resistance state to a high resistance state.

Fig. 3 is the cycle stability test result of the memristor prepared in Example 1, it is repeatedly erased and written in the process, it is found that it has good stability, the on-off ratio is about 100, and it can be normal for 33 times operate.

Example 2

A memristor based on a covalent organic framework (COF) film in this embodiment includes a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer, and a conductive top electrode from bottom to top; wherein: The thicknesses of the substrate, conductive bottom electrode, covalent organic framework film, organic polymer barrier layer and conductive top electrode are 2cm, 100nm, 90nm, 50nm and 60nm in sequence.

The above-mentioned memristor based on covalent organic framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Clean the 2cm×2cm×2cm ITO glass, put it on the glass cleaning rack, immerse it in ultrapure water for ultrasonic cleaning for 30 minutes, then replace it with acetone for ultrasonic cleaning for 30 minutes, and finally replace it with absolute ethanol for 30 minutes , and finally take it out and dry it in a drying oven at 60°C for 6 hours.

(2) Weigh 10 mg of biphenyldiformaldehyde in a small weighing bottle, successively add 2 ml of absolute ethanol, 2 ml of mesitylene and 400 μL of acetic acid; weigh 8 mg of tris( 4-Aminophenyl)amine (TAPA), add 2ml of ethanol, 2ml of mesitylene and 400μL of acetic acid, after it is fully dissolved, mix the two bottles of solutions, take 200μL dropwise on the surface of ITO placed horizontally, wait After reacting for 7 minutes, the unreacted solution was rinsed with ethanol, and dried at room temperature for 12 hours to obtain a covalent organic framework film; wherein:

The ratio of the amount of biphenyldiformaldehyde to TAPA in the biphenyldiformaldehyde mixed solution and the TAPA mixed solution is 0.0000439:0.00002755.

(3) Preparation of PVA colloidal liquid: Take 0.1g PVA and dissolve it in 10ml ultrapure water at 90°C to obtain a colloidal solution. Take 40 μL of the colloidal solution and spin-coat it on the surface of the covalent organic framework film. The spin-coating parameters are 3000rmp, spin-coating time is 20s to obtain an organic polymer barrier layer.

(4) Sputtering a tungsten electrode on the surface of the organic frame film PVA with a mask.

The I-V characteristics of the covalent organic framework (COF) film-based memristor device prepared in this example were tested with a semiconductor device analyzer.

Fig. 4 is the switching characteristic curve of the memristor prepared in Example 2, and the direction of the curve change is as shown by the arrows (the order of the arrows is consistent with that in Fig. 2), and the initial resistance state of the memristor is a high resistance state, which is the same as that of many memristors. Unlike memristors, this memristor requires a negative sweep voltage to bring it into a low-impedance state. As shown in Figure 4, start scanning with a voltage of 0V→-1.2V→0V, limit the current to A, and when the voltage is -1.15V, the memristor will switch from a high-impedance state to a low-impedance state. Afterwards, the voltage of 0V→2V→0V is scanned, and when the voltage is 0.4V, the memristor will be converted from a low-resistance state to a high-resistance state.

Fig. 5 is the cycle stability test result of the memristor prepared in Example 2. It is found that the memristor has good stability after repeated erasing and writing, and the switch can perform 65 normal operations.

Example 3

A memristor based on a covalent organic framework (COF) film in this embodiment includes a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer, and a conductive top electrode from bottom to top; wherein: The thicknesses of the substrate, conductive bottom electrode, covalent organic framework film, organic polymer barrier layer and conductive top electrode are 1 cm, 100 nm, 150 nm, 50 nm and 60 nm in sequence.

The above-mentioned memristor based on covalent organic framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Clean the 2cm×2cm×1cm ITO glass, put it on the glass cleaning rack, immerse it in ultrapure water for ultrasonic cleaning for 30 minutes, then replace it with acetone for ultrasonic cleaning for 30 minutes, and finally replace it with absolute ethanol for 30 minutes , and finally take it out and dry it in a drying oven at 60°C for 6 hours.

(2) Weigh 8 mg of terephthalaldehyde in a small weighing bottle, successively add 2 ml of absolute ethanol, 2 ml of mesitylene and 400 μL of acetic acid; weigh 8 mg of tris( 4-Aminophenyl)amine (TAPA), add 2ml of ethanol, 2ml of mesitylene and 400μL of acetic acid, after it is fully dissolved, mix the two bottles of solutions, take 200μL dropwise on the surface of ITO placed horizontally, wait After reacting for 10 minutes, rinse the unreacted solution with ethanol, and dry at room temperature for 12 hours to obtain a covalent organic framework film; wherein:

The ratio of the amount of terephthalaldehyde to TAPA in the terephthalaldehyde mixed solution and the TAPA mixed solution is 0.00005964:0.00002755.

(3) Preparation of PMMA colloidal liquid: get 0.1g PMMA and dissolve it in 20ml chlorobenzene at 90°C to obtain a colloidal solution, get 40 μL of the colloidal solution and spin-coat it on the surface of the covalent organic framework film, and the spin-coating parameter is 3000rmp , and the spin coating time was 20s to obtain an organic polymer barrier layer.

(4) Sputtering a tungsten electrode on the surface of the organic polymer barrier layer PMMA with a mask.

The I-V characteristics of the covalent organic framework (COF) film-based memristor device prepared in this example were tested with a semiconductor device analyzer.

Fig. 6 is the switching characteristic curve of the memristor prepared in Example 3, and the change direction of the curve is as shown by the arrows (the order of the arrows is consistent with that in Fig. 2), and the initial resistance state of the memristor is a high resistance state, which is the same as that of many memristors. Unlike memristors, this memristor requires a negative sweep voltage to bring it into a low-impedance state. As shown in Figure 6, start to scan with a voltage of 0V→-2V→0V, and limit the current to A, which will make the memristor switch from a high-impedance state to a low-impedance state. Afterwards, a voltage sweep of 0V→2.2V→0V will cause the memristor to switch from a low-resistance state to a high-resistance state.

Figure 7 shows the cycle stability test results of the memristor prepared in Example 3. It was repeatedly erased and written, and it was found to have good stability. The on-off ratio is about 100, and 105 times of normal operate.

Example 4

A memristor based on a covalent organic framework (COF) film in this embodiment includes a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer, and a conductive top electrode from bottom to top; wherein: The thicknesses of the substrate, conductive bottom electrode, covalent organic framework film, organic polymer barrier layer and conductive top electrode are 2cm, 100nm, 800nm, 50nm and 60nm in sequence.

The above-mentioned memristor based on covalent organic framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Clean the 2cm×2cm×2cm ITO glass, put it on the glass cleaning rack, immerse it in ultrapure water for ultrasonic cleaning for 30 minutes, then replace it with acetone for ultrasonic cleaning for 30 minutes, and finally replace it with absolute ethanol for 30 minutes , and finally take it out and dry it in a drying oven at 60°C for 6 hours.

(2) Weigh 10 mg of biphenyldiformaldehyde in a small weighing bottle, successively add 2 ml of absolute ethanol, 2 ml of mesitylene and 400 μL of acetic acid; weigh 8 mg of tris( 4-Aminophenyl)amine (TAPA), add 2ml of ethanol, 2ml of mesitylene and 400μL of acetic acid, after it is fully dissolved, mix the two bottles of solutions, take 300μL dropwise on the surface of ITO placed horizontally, wait After reacting for 15 minutes, the unreacted solution was rinsed with ethanol, and dried at room temperature for 12 hours to obtain a covalent organic framework film; wherein:

The ratio of the amount of biphenyldiformaldehyde to TAPA in the biphenyldiformaldehyde mixed solution and the TAPA mixed solution is 0.0000549:0.00002755.

(3) Preparation of PVA colloidal liquid: take 0.2g polyvinyl alcohol (PVA) (molecular weight: 1750±50) and dissolve it in 10ml ultrapure water at 90°C to obtain a colloidal solution, and take 40 μL of the colloidal solution for spin coating On the surface of the covalent organic framework film, the spin coating parameter is 3000rmp, and the spin coating time is 20s to obtain an organic polymer barrier layer.

(4) A tungsten electrode was sputtered on the surface of the organic polymer barrier layer PVA with a self-made mask.

The I-V characteristics of the covalent organic framework (COF) film-based memristor device prepared in this example were tested with a semiconductor device analyzer.

Fig. 8 is the switching characteristic curve of the memristor prepared in Example 4, and the direction of the change of the curve is as shown by the arrow. The initial resistance state of the memristor is a high resistance state. Due to the increase in the amount of the reacting monomer, the reaction time It is also extended, so the thickness of the film increases, and it is necessary to use a positive scanning voltage to make it enter a low-resistance state. As shown in Figure 8, starting to scan with a voltage of 0V→3V→0V will cause the memristor to switch from a high-resistance state to a low-resistance state without limiting the current. mutation. Afterwards, a voltage sweep of 0V→-3V→0V will cause the memristor to switch from a low-resistance state to a high-resistance state.

Fig. 9 shows the cycle stability test results of the memristor prepared in Example 4. After repeated erasing and writing, it is found that it has good stability, and the switch can perform 34 normal operations.

Compared with Example 2, Example 4 increased the amount of reaction solution (200 μ L → 300 μ L), increased the reaction time (7min → 15min), from the test results, the cycle stability of Example 4 is relatively poor, especially The retention characteristic of high resistance is poor, and the number of cycles is significantly smaller than that of Example 2. SEM characterization was carried out on them, and it was found that the thickness of the covalent organic framework film in Example 2 (Figure 10) was about 90nm, and the surface was relatively smooth, and the overall thickness was relatively uniform; The thickness is about 800nm, and the thickness is not uniform, and there are many aggregates on the surface. Therefore, it can be seen that changing the reaction time and the amount of reactants can change the thickness of the film. It is speculated that the thickness and uniformity should be the reason for the difference in performance.

The present invention has been exemplarily described above, and it should be noted that any simple deformation, modification or other equivalent replacements that those skilled in the art can do without creative work all fall within the scope of the present invention without departing from the core of the present invention. scope of protection.

Claims (10)

1. A memristor based on Covalent Organic Framework (COF) thin film is characterized in that: the organic solar cell comprises a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer barrier layer and a conductive top electrode from bottom to top in sequence.

2. The memristor according to claim 1, wherein: the thickness of the covalent organic framework film is 100-150nm, and the thickness of the organic polymer barrier layer is 60-200nm.

3. The memristor according to claim 1, wherein: the covalent organic framework film is prepared by adopting the following method: mixing the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution at 0-80 ℃ in an atmospheric environment, quickly dripping the obtained mixed solution on the surface of a conductive bottom electrode or directly soaking a substrate with the conductive bottom electrode in the mixed solution to obtain a layer of uniform covalent organic framework film on the surface of the substrate.

4. The memristor according to claim 1, wherein: the ratio of the amounts of the aromatic dialdehyde and the aromatic polyamine in the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution is as follows: (0.00002755-0.00005964): 0.00002755.

5. the memristor according to claim 1, wherein: the aromatic dialdehyde mixed solution is prepared by adopting the following method: weighing aromatic dialdehyde according to a ratio, then sequentially adding an organic solvent A, an organic solvent B and an organic acid C, and fully dissolving to obtain a transparent colorless aromatic dialdehyde mixed solution, wherein the concentration of the aromatic dialdehyde in the aromatic dialdehyde mixed solution is 0.00626-0.01355 mol/L, and the volume ratio of the organic acid is 5-10%.

6. The memristor according to claim 1, wherein: the aromatic polyamine mixed solution is prepared by adopting the following method: weighing aromatic polyamine according to a ratio, then sequentially adding an organic solvent A, an organic solvent B and an organic acid C, and fully dissolving to obtain a dark green aromatic polyamine mixed solution, wherein the concentration of the aromatic polyamine in the aromatic polyamine mixed solution is 0.00626mmol/L, and the volume ratio of the organic acid is 5-10%.

7. The memristor according to claim 1, wherein: the organic polymer barrier layer is prepared by the following method:

and (2) dissolving the organic polymer A in the liquid B at 80-100 ℃ to obtain a colloidal solution, and spin-coating the colloidal solution on the surface of the covalent organic framework film by adopting a spin-coating method.

8. The memristor of claim 7, wherein: the organic polymer A is polyvinyl alcohol or polymethyl methacrylate.

9. The memristor of claim 7, wherein: the mass-volume ratio of the polymer A to the liquid B in the colloidal solution is 1-20 mg/mL.

10. A method of making a memristor as in any of claims 1-9, wherein: the method specifically comprises the following steps:

(1) Cleaning the substrate with the conductive bottom electrode, and then drying;

(2) Growing a covalent organic framework film on the surface of the clean and dry bottom electrode, and then drying;

(3) Spinning the colloid solution on the covalent organic framework film to obtain an organic polymer barrier layer;

(4) And preparing the conductive top electrode on the surface of the organic polymer barrier layer by adopting a thermal evaporation or magnetron sputtering mode.

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