CN115915775A - Memristor based on Covalent Organic Framework (COF) film and preparation method thereof - Google Patents

Abstract

The invention discloses a memristor based on a covalent organic framework film, which is structurally characterized in that: a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer film, and a conductive top electrode. The preparation method of the memristor comprises the following steps: at the temperature of 0-80 ℃, mixing a specific aromatic dialdehyde mixed solution and an aromatic polyamine mixed solution, dripping the mixed solution on a required conductive bottom electrode or directly soaking a substrate with the conductive bottom electrode in the mixed solution to obtain a uniform covalent organic framework film on the bottom electrode for the memristor. And then preparing a polymer colloid solution, spin-coating the polymer colloid solution on the surface of the covalent organic framework film, and finally preparing the top electrode by using a mask plate through thermal evaporation or sputtering. The invention provides a preparation method of a novel memristor for the first time, the preparation method is simple in process and economical in price, a high-precision precise instrument is not needed, and a large-area Covalent Organic Framework (COF) film can be prepared by in-situ growth on a substrate under the condition of not needing a complex environment.

Description

Memristor based on Covalent Organic Framework (COF) film and preparation method thereof

Technical Field

The invention belongs to the technical field of organic two-dimensional material application, and particularly relates to a memristor based on a Covalent Organic Framework (COF) film and a preparation method thereof.

Background

Covalent Organic Frameworks (COF) material is a new porous material that has received a great deal of attention due to its interesting structural advantages, such as overall Organic framework, tunable porosity and predictable structure. However, the insoluble and non-processable nature of covalent organic framework powders limits their applications. At present, covalent organic framework materials have been widely researched and show excellent application prospects in the fields of gas storage and separation, heterogeneous catalysis, energy storage materials, photoelectricity, sensing, drug delivery and the like. Heretofore, some researchers have made available memristors using covalent organic framework materials.

However, most COF synthesis methods are complicated and long in reaction time, are generally synthesized by a solvothermal method and need to react for several days under a High-temperature and High-pressure environment, for example, COF-TT-BT and COF-TT-TVT films synthesized by articles Towards High-Performance reactive Switching Behavier through Embedding D-A System into 2D Imine-Linked equivalent Organic framework need to react for 72 hours at 120 ℃. Moreover, many memristors prepared by using covalent organic frameworks are not grown in situ, and transfer operation is required (for example, patent CN 2018102788065), so that the preparation process is complicated. In addition, many memristors prepared by using covalent organic frameworks are of three-layer structures (bottom electrodes, thin films and top electrodes) and have no barrier layer, the top electrodes are generally prepared by adopting a thermal evaporation or sputtering mode, the organic covalent framework thin films are of an ordered structure containing one-dimensional channels and are provided with larger hole structures, metal easily invades into the thin films by directly evaporating or sputtering on the surfaces of the thin films, the thickness of the thin films is reduced, and the accidental performance of device preparation is improved.

The present application has been made for the above reasons.

Disclosure of Invention

For the above reasons, the present invention aims to provide a memristor based on a Covalent Organic Framework (COF) thin film and a method for preparing the memristor, which solves or at least partially solves the technical defects in the prior art. The Covalent Organic Framework (COF) can be rapidly grown on the surface of various flat substrates in situ in the atmosphere within a wide temperature range, and films with different thicknesses can be obtained by changing the concentration, the molar quantity and the reaction time of the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution, so that memristors with structures with different thicknesses can be conveniently manufactured.

In order to achieve the first object of the present invention, the present invention adopts the following technical solutions:

a memristor based on a Covalent Organic Framework (COF) film sequentially comprises a substrate, a conductive bottom electrode, the covalent organic framework film, an organic polymer barrier layer and a conductive top electrode from bottom to top.

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

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

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

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

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

Further, in the technical scheme, 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.

Furthermore, the covalent organic framework film is prepared by adopting an in-situ growth mode, and the specific operation steps are as follows:

uniformly mixing the aromatic dialdehyde mixed solution and the aromatic polyamine mixed solution according to the proportion, then dripping 50-300 mu L of the mixed solution on the surface of the substrate with the conductive bottom electrode by using a liquid transfer gun, waiting for 2-15min, or directly soaking the substrate with the conductive bottom electrode in the uniformly mixed solution for 2-15min, then taking out the substrate, cleaning by using an organic solvent D, removing redundant reactants, and finally drying at room temperature.

Preferably, in the above technical solution, 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: (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.

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

Preferably, in the above technical scheme, the aromatic dialdehyde mixed solution is prepared by 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%.

Preferably, in the above technical solution, the aromatic polyamine mixed solution is prepared by 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 0.00626mol/L, and the volume ratio of the organic acid is 5-10%.

Preferably, in the above technical scheme, the aromatic dialdehyde is any one of terephthalaldehyde, isophthalaldehyde or biphenyldicarbaldehyde.

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

More preferably, in the above technical solution, the organic solvent a is ethanol or isopropanol.

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

Preferably, in the above technical scheme, the organic acid C is acetic acid or succinic acid.

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

and (2) dissolving the organic polymer A in the liquid B at the temperature of 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.

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 solution, the liquid B is any one of deionized water, dichloromethane, dimethyl sulfoxide, dichloroethane, chloroform, acetone, methyl ethyl ketone, benzene, chlorobenzene, tetrahydrofuran, or the like. It should be noted that, since PVA is hardly soluble in an organic solvent, when the organic polymer a is polyvinyl alcohol (PVA), it is necessary that the liquid B used therefor is deionized water.

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

The second purpose of the present invention is to provide a method for preparing the memristor based on the Covalent Organic Framework (COF) thin film, which 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 frame 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.

Compared with the prior art, the invention has the advantages that:

(1) The invention can rapidly grow various flat substrate surfaces in situ (about 10 min) in a wider temperature range, has simple preparation method, does not relate to precise and expensive instruments, uses medicines which are produced in a factory in a large scale and has economic price.

(2) The memristor is composed of a 5-layer structure, and comprises a substrate, a conductive bottom electrode, a covalent organic framework film, an organic barrier layer and a conductive top electrode from bottom to top. The substrate and the conductive bottom electrode can be regarded as one part, for example, the substrate and the conductive bottom electrode can be glass sheets with ITO or silicon sheets with metal films, and only play a role in supporting and conducting electricity, so the thickness of the substrate and the conductive bottom electrode has no obvious influence on the performance of the device; the covalent organic framework film is a core structure, is a core of a memristor capable of generating resistance change, has the best performance and the most stable performance when being about 100nm thick, is easy to break down into a conductor when being too thin, and is difficult to generate resistance change when being too thick; the organic barrier layer primarily serves to prevent the intrusion of the metal top electrode, which is also a difference of the present invention from many other inventions. The top electrode is prepared in a sputtering or thermal evaporation mode, if no barrier layer exists, metal can enter the film randomly, the preparation contingency of the device is greatly improved, and the stability of the device is reduced; the conductive top electrode and the conductive bottom electrode both play a conductive role, but the top electrode is optimal in thickness of 60-100nm, and too thin is easily pierced by a test needle during testing to cause failure in testing, and too thick needs to increase the time of sputtering or thermal evaporation, possibly damages the film and increases the cost.

Drawings

FIG. 1 is a schematic diagram of a structure of a Covalent Organic Framework (COF) thin film based memristor of the present invention;

FIG. 2 is a switching characteristic curve of a memristor prepared from example 1;

FIG. 3 is a cycle stability test result of the memristor prepared in example 1;

FIG. 4 is a switching characteristic curve of a memristor prepared in example 2;

FIG. 5 is a cycle stability test result of the memristor prepared in example 2;

FIG. 6 is a switching characteristic curve of a memristor prepared in example 3;

FIG. 7 is a cycle stability test result of the memristor prepared from example 3;

FIG. 8 is a switching characteristic curve of a memristor prepared in example 4;

FIG. 9 is a cycle stability test result of the memristor prepared in example 4;

FIG. 10 is a scanning electron microscope image of the covalent organic framework thin film prepared in example 2;

FIG. 11 is a scanning electron micrograph of a thin film of the covalent organic framework prepared in example 4.

Detailed Description

The present invention will be described in further detail below with reference to examples.

For a better understanding of the invention, without limiting the scope thereof, all numbers expressing quantities, percentages, and other numerical values used in this application are to be understood as being modified in all instances by the term "about". Accordingly, unless otherwise indicated, the numerical parameters set forth in the specification are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least 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 framework film, which is structurally characterized in that: a substrate, a conductive bottom electrode, a covalent organic framework film, an organic polymer film, and a conductive top electrode. The preparation method of the memristor comprises the following steps: at the temperature of 0-80 ℃, mixing a specific aromatic dialdehyde mixed solution and an aromatic polyamine mixed solution, dripping the mixed solution on a required conductive bottom electrode or directly soaking a substrate with the conductive bottom electrode in the mixed solution to obtain a uniform covalent organic framework film on the bottom electrode for the memristor. And then preparing a polymer colloid solution, spin-coating the polymer colloid solution on the surface of the covalent organic framework film, and finally preparing the top electrode by using a mask plate through thermal evaporation or sputtering. The invention provides a preparation method of a novel memristor for the first time, the preparation method is simple in process and economical in price, a high-precision precise instrument is not needed, and a large-area Covalent Organic Framework (COF) film can be prepared by in-situ growth on a substrate under the condition of not needing a complex environment.

In a particular embodiment of the invention, the apparatus concerned is as follows:

ultrasonic cleaning instrument

Spin coating instrument

Thermal evaporation coating apparatus

Agilent Techodies B1500A semiconductor device analyzer and probe station

Scanning electron microscope

The medicine purchase sources involved are:

the aromatic dialdehyde and aromatic polyamine are purchased from Shanghai leaf Biotechnology GmbH, and the rest reagents are purchased from the national drug group, and the purity is analytical purity.

Description of the test methods:

switching characteristic curve: the test is carried out by using an Agilent Techtools B1500A semiconductor device analyzer and a probe station, a voltage is applied on the conductive top electrode, the conductive bottom electrode is grounded, the test voltage is applied in a mode of 0V → negative cut-off voltage → 0V → positive cut-off voltage → 0V, and the test result corresponds to the test result, taking the 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, and positive cut-off voltage → 0V corresponds to 4 in the figure. The step size during the positive voltage sweep (i.e., 0V → positive cutoff voltage → 0V) is positive cutoff voltage/100, and the step size during the negative voltage sweep (i.e., 0V → negative cutoff voltage → 0V) is negative cutoff voltage/100.

And (3) testing the cycling stability: the switching characteristic test is repeatedly carried out, a switching characteristic curve (namely, the voltage 0V → the negative cut-off voltage → 0V → the positive cut-off voltage → the scanning of 0V) is regarded as a cycle, the switching characteristic test is repeatedly carried out by utilizing the cycle test function test carried by the semiconductor analyzer, and then two resistance values of a certain voltage point of all cycles are selected according to the performances of different devices for drawing. Taking example 1 as an example, the resistance values of two points in the high resistance state and the low resistance state at 0.25V are selected, the resistance values at 0.25V are taken for all cycles, and then the cycle stability test scatter diagram is obtained by plotting.

Example 1

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

The memristor based on the Covalent Organic Framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Cleaning ITO glass of 2cm multiplied by 1cm, putting the cleaned ITO glass on a glass cleaning frame, immersing the cleaned ITO glass in ultrapure water for ultrasonic cleaning for 30min, then changing the cleaned ITO glass into acetone for ultrasonic cleaning for 30min, finally changing the cleaned ITO glass into absolute ethyl alcohol for ultrasonic cleaning for 30min, finally taking out the cleaned ITO glass, and drying the cleaned ITO glass in a drying oven at 60 ℃ for 6h.

(2) Weighing 8mg of terephthalaldehyde in a small weighing bottle, and adding 2ml of absolute ethyl alcohol, 2ml of mesitylene and 400 mu L of acetic acid in sequence; weighing 8mg of tris (4-aminophenyl) amine (TAPA) in another small weighing bottle, adding 2ml of ethanol, 2ml of mesitylene and 400 mu L of acetic acid, and mixing the two bottles of solution uniformly after the solution is fully dissolved; dripping 200 mu L of the solution on the surface of horizontally placed ITO, washing the unreacted solution with ethanol after the reaction is carried out for 10min, and drying the solution at room temperature for 12h to obtain a covalent organic framework film; wherein:

the ratio of the amounts of terephthalaldehyde to TAPA in the mixed terephthalaldehyde solution and TAPA solution was 0.00005964.

(3) Preparation of PVA colloidal liquid: dissolving 0.2g polyvinyl alcohol (PVA) (molecular weight 1750 + -50) in 10ml ultrapure water at 90 deg.C to obtain colloidal solution; and (3) taking 40 mu L of the colloidal solution to spin-coat the surface of the covalent organic framework thin film, wherein the spin-coating parameter is 3000rmp, and the spin-coating time is 20s, so that the organic polymer barrier layer is obtained.

(4) And (3) evaporating an Al electrode on the surface of the organic polymer barrier layer by using a mask.

The I-V characteristics of the memristor device based on the Covalent Organic Framework (COF) film prepared in the example were tested by a semiconductor device analyzer.

Fig. 2 is a switching characteristic curve of the memristor prepared in example 1, a curve change direction of the memristor is shown by an arrow, an initial resistance state of the memristor is a high resistance state, and the memristor needs to be brought into a low resistance state by a negative scanning voltage unlike many memristors. As shown in fig. 2, the voltage sweep of 0V → -1.5V → 0V is started, the current is limited to a, and the memristor will be switched from the high resistance state to the low resistance state when the voltage is-0.25V. And then, scanning by a voltage of 0V → 1V → 0V, wherein the memristor is converted from a low resistance state to a high resistance state when the voltage is 0.7V.

Fig. 3 shows the results of the cycling stability test of the memristor prepared in example 1, which was repeatedly erased and written, and found to have good stability, the on-off ratio is about 100, and 33 times of normal operations can be performed.

Example 2

The memristor based on a Covalent Organic Framework (COF) film of the embodiment sequentially 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; wherein: the substrate, the conductive bottom electrode, the covalent organic framework film, the organic polymer barrier layer and the conductive top electrode are 2cm, 100nm, 90nm, 50nm and 60nm in thickness in sequence.

The memristor based on the Covalent Organic Framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Cleaning ITO glass of 2cm multiplied by 2cm, putting the cleaned ITO glass on a glass cleaning frame, immersing the cleaned ITO glass in ultrapure water for ultrasonic cleaning for 30min, then changing the cleaned ITO glass into acetone for ultrasonic cleaning for 30min, finally changing the cleaned ITO glass into absolute ethyl alcohol for ultrasonic cleaning for 30min, finally taking out the cleaned ITO glass, and drying the cleaned ITO glass in a drying oven at 60 ℃ for 6h.

(2) Weighing 10mg of biphenyldicarboxaldehyde in a small weighing bottle, and adding 2ml of absolute ethyl alcohol, 2ml of mesitylene and 400 mu L of acetic acid in sequence; weighing 8mg of tris (4-aminophenyl) amine (TAPA) in another small weighing bottle, adding 2ml of ethanol, 2ml of mesitylene and 400 mu L of acetic acid, mixing the two bottles of solutions after the solutions are fully dissolved, dropwise adding 200 mu L of the solution on the surface of horizontally placed ITO, washing the unreacted solution with ethanol after the solution reacts for 7min, and drying the solution at room temperature for 12h to obtain a covalent organic framework film; wherein:

the mass ratio of the biphenyldicarboxaldehyde to the TAPA in the biphenyldicarboxaldehyde and TAPA mixed solutions was 0.0000439.

(3) Preparation of PVA colloidal liquid: and (3) dissolving 0.1g of PVA in 10ml of ultrapure water at 90 ℃ to obtain a colloidal solution, and spin-coating 40 mu L of the colloidal solution on the surface of the covalent organic framework film at the spin-coating parameter of 3000rmp for 20s to obtain the organic polymer barrier layer.

(4) And sputtering a tungsten electrode on the surface of the organic frame film PVA by using a mask.

The I-V characteristics of the memristor devices based on Covalent Organic Framework (COF) thin films prepared in this example were tested with a semiconductor device analyzer.

Fig. 4 is a switching characteristic curve of the memristor prepared in example 2, a curve change direction of the memristor is shown by an arrow (the arrow sequence is the same as that in fig. 2), an initial resistance state of the memristor is a high resistance state, and the memristor needs to be brought into a low resistance state by a negative scan voltage unlike many memristors. As shown in fig. 4, a voltage sweep of 0V → -1.2V → 0V is started, the current is limited to a, and the memristor is switched from the high resistance state to the low resistance state at a voltage of-1.15V. And then, scanning by a voltage of 0V → 2V → 0V, wherein the memristor is converted from a low resistance state to a high resistance state when the voltage is 0.4V.

Fig. 5 shows the results of the cycling stability test of the memristor prepared in example 2, which was repeatedly erased and written, and found to have good stability, and the switch can perform 65 times of normal operations.

Example 3

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

The memristor based on the Covalent Organic Framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Cleaning ITO glass with the thickness of 2cm multiplied by 1cm, putting the ITO glass on a glass cleaning rack, immersing the ITO glass in ultrapure water for ultrasonic cleaning for 30min, then changing the ITO glass into acetone for ultrasonic cleaning for 30min, finally changing the ITO glass into absolute ethyl alcohol for ultrasonic cleaning for 30min, finally taking out the ITO glass, and drying the ITO glass in a drying oven with the temperature of 60 ℃ for 6h.

(2) Weighing 8mg of terephthalaldehyde in a small weighing bottle, and adding 2ml of absolute ethyl alcohol, 2ml of mesitylene and 400 mu L of acetic acid in sequence; weighing 8mg of tris (4-aminophenyl) amine (TAPA) in another small weighing bottle, adding 2ml of ethanol, 2ml of mesitylene and 400 mu L of acetic acid, mixing the two bottles of solutions after the solutions are fully dissolved, dropwise adding 200 mu L of the solution on the surface of horizontally placed ITO, washing the unreacted solution with ethanol after the solution reacts for 10min, and drying the solution at room temperature for 12h to obtain a covalent organic framework film; wherein:

the ratio of the amounts of terephthalaldehyde to TAPA in the mixed terephthalaldehyde solution and TAPA solution was 0.00005964.

(3) Preparation of PMMA colloidal liquid: dissolving 0.1g of PMMA in 20ml of chlorobenzene at 90 ℃ to obtain a colloidal solution, and spin-coating 40 mu L of the colloidal solution on the surface of the covalent organic framework thin film at the spin-coating parameter of 3000rmp for 20s to obtain the organic polymer barrier layer.

(4) And sputtering a tungsten electrode on the surface of the organic polymer barrier layer PMMA by using a mask.

The I-V characteristics of the memristor devices based on Covalent Organic Framework (COF) thin films prepared in this example were tested with a semiconductor device analyzer.

Fig. 6 is a switching characteristic curve of the memristor prepared in example 3, a curve change direction of the memristor is shown by an arrow (the arrow sequence is the same as that in fig. 2), an initial resistance state of the memristor is a high resistance state, and the memristor needs to be brought into a low resistance state by a negative scan voltage unlike many memristors. As shown in fig. 6, a voltage sweep of 0V → -2V → 0V is started, and the memristor is switched from the high resistance state to the low resistance state by limiting the current to a. And then scanning by a voltage of 0V → 2.2V → 0V, so that the memristor is converted from a low resistance state to a high resistance state.

Fig. 7 shows the results of the cycling stability test of the memristor prepared in example 3, which was repeatedly erased and written, and found to have good stability, and the on-off ratio is about 100, and 105 times of normal operations can be performed.

Example 4

The memristor based on a Covalent Organic Framework (COF) film of the embodiment sequentially 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; wherein: the thickness of the substrate, the thickness of the conductive bottom electrode, the thickness of the covalent organic framework film, the thickness of the organic polymer barrier layer and the thickness of the conductive top electrode are sequentially 2cm, 100nm, 800nm, 50nm and 60nm.

The memristor based on the Covalent Organic Framework (COF) film is prepared by the following method, and the specific steps are as follows:

(1) Cleaning ITO glass of 2cm multiplied by 2cm, putting the ITO glass on a glass cleaning rack, immersing the ITO glass in ultrapure water for ultrasonic cleaning for 30min, then changing the ITO glass into acetone for ultrasonic cleaning for 30min, finally changing the acetone for ultrasonic cleaning into absolute ethyl alcohol for ultrasonic cleaning for 30min, finally taking out the ITO glass, and drying the ITO glass in a drying oven of 60 ℃ for 6h.

(2) Weighing 10mg of biphenyldicarboxaldehyde in a small weighing bottle, and sequentially adding 2ml of absolute ethyl alcohol, 2ml of mesitylene and 400 mu L of acetic acid; weighing 8mg of tris (4-aminophenyl) amine (TAPA) in another small weighing bottle, adding 2ml of ethanol, 2ml of mesitylene and 400 mu L of acetic acid, mixing the two bottles of solutions after the solutions are fully dissolved, dropwise adding 300 mu L of the solution on the surface of horizontally placed ITO, washing the unreacted solution with ethanol after the solution reacts for 15min, and drying the solution at room temperature for 12h to obtain a covalent organic framework film; wherein:

the substance quantity ratio of the biphenyldicarboxaldehyde to the TAPA in the biphenyldicarboxaldehyde mixed solution and the TAPA mixed solution is 0.0000549.

(3) Preparation of PVA colloidal liquid: 0.2g of polyvinyl alcohol (PVA) (the molecular weight is 1750 +/-50) is dissolved in 10ml of ultrapure water at the temperature of 90 ℃ to obtain a colloidal solution, 40 mu L of the colloidal solution is taken to be spin-coated on the surface of the covalent organic framework film, the spin-coating parameter is 3000rmp, and the spin-coating time is 20s, so that the organic polymer barrier layer is obtained.

(4) And sputtering a tungsten electrode on the surface of the organic polymer barrier layer PVA by using a self-made mask.

The I-V characteristics of the memristor devices based on Covalent Organic Framework (COF) thin films prepared in this example were tested with a semiconductor device analyzer.

Fig. 8 is a switching characteristic curve of the memristor prepared in example 4, the curve change direction is shown by an arrow, the initial resistance state of the memristor is a high resistance state, the amount of the reactive monomer substance is increased, the reaction time is also prolonged, the film thickness is increased, and the positive scanning voltage is required to make the film enter the low resistance state. As shown in fig. 8, starting the voltage sweep of 0V → 3V → 0V will make the memristor switch from the high resistance state to the low resistance state, without limiting the current, and the configuration change is gradual rather than abrupt, unlike embodiment 2. And then, scanning with a voltage of 0V → -3V → 0V, so that the memristor is converted from a low resistance state to a high resistance state.

Fig. 9 shows the results of the cycling stability test of the memristor prepared in example 4, which was repeatedly erased and written, and found to have good stability, and the switch can perform 34 times of normal operations.

Example 4 increased the amount of the reaction solution (200 μ L → 300 μ L) and the reaction time (7 min → 15 min) compared to example 2, and from the test results, example 4 was inferior in cycle stability, particularly in retention property of high resistance, and the number of cycles was significantly smaller than example 2. SEM characterization of the thin films shows that the thickness of the covalent organic framework thin film of the example 2 (figure 10) is about 90nm, the surface is flat, and the overall thickness is uniform; whereas the covalent organic framework film of example 4 (FIG. 11) had a thickness of about 800nm and was not uniform, with many agglomerates on the surface, it can be seen that varying the reaction time and the amount of reactants can vary the film thickness, presumably because of differences in properties.

The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which may occur to those skilled in the art without departing from the spirit and the scope of the invention may be considered to be within the scope of the invention.

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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