2-(2 '-hydroxyphenyl)-benzothiazole, synthesis method and application in preparation of resistive random access memory

Abstract

The invention discloses 2-(2 '-hydroxyphenyl)-benzothiazole and a synthesis method thereof, salicylaldehyde and 2-aminothiophenol are subjected to a one-step reaction to synthesize the 2-(2'-hydroxyphenyl)-benzothiazole, the yield is high, the adopted organic molecular raw material is low in price, the synthesis steps are simple, and the 2-(2 '-hydroxyphenyl)-benzothiazole is convenient for industrial application; meanwhile, the resistive random access memory prepared from the 2-(2 '-hydroxyphenyl)-benzothiazole has better resistive random access performance.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and resistive memory device preparation, and specifically relates to a synthesis method of 2-(2'-hydroxyphenyl)-benzothiazole (HBT) and an application of the HBT in the preparation of resistive memory. Background Art

[0002] In recent years, inorganic resistive memory has matured in technology, but there is little room for improvement. In addition, inorganic materials have poor flexibility. With the development of computer technology, it can no longer meet people's needs for daily wearable flexible devices. Organic molecules can introduce electron donors or acceptors in the molecular structure through molecular design to flexibly regulate the resistive properties of the material. Organic resistive memory has attracted widespread attention due to its advantages such as low manufacturing cost, simple process, bendability, high performance, easy processing and controllability. It is a hot candidate for the next generation of resistive materials. However, although many organic molecules have been applied to resistive memory, there is still no clear conclusion on the resistive mechanism of organic molecules. At present, the models proposed by the scientific community for the resistive mechanism of the resistance transition effect of organic resistive memory include charge transfer, conformational change, charge capture-release, and conductive filaments.

[0003] Organic molecules with intramolecular hydrogen bonds, such as phenol and its derivatives connected to heterocyclic rings ( Figure 1 As shown in FIG. 1 , due to the presence of hydrogen bonds within its molecules, it has at least two molecular structures, and different molecular structures have different electrical properties, so it is possible to be used as an active layer material for a resistive random access memory.

[0004] Therefore, the present invention synthesizes an organic small molecule 2-(2'-hydroxyphenyl)-benzothiazole (HBT) with intramolecular hydrogen bonds, and successfully applies it to the preparation of resistive random access memory. Summary of the invention

[0005] The purpose of the present invention is to provide 2-(2'-hydroxyphenyl)-benzothiazole (HBT) and a synthesis method thereof, and at the same time, to provide the application of 2-(2'-hydroxyphenyl)-benzothiazole (HBT) in the preparation of resistive random access memory and the preparation of application devices is another invention purpose of the present invention. A class of organic small molecules with intramolecular hydrogen bonds are synthesized based on the HBT molecule, and the resistive random access properties of the series of molecules are tested, thereby proving that a class of organic molecules with intramolecular hydrogen bonds have the potential to be applied to resistive random access memory, among which the resistive random access effect of HBT is the most significant.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, the present invention provides a method for synthesizing 2-(2'-hydroxyphenyl)-benzothiazole (HBT), comprising the following steps:

[0008] 1) Stir and dissolve sodium metabisulfite, salicylaldehyde and N'N-dimethylformamide;

[0009] 2) adding 2-aminothiophenol to the above reaction solution, and refluxing at 153-191° C. under protective gas protection;

[0010] 3) After the reaction is completed, the mixture is cooled naturally and purified to obtain a white solid.

[0011] As a further preferred embodiment of the present invention, the usage ratio of the sodium metabisulfite, salicylaldehyde, N'N-dimethylformamide and 2-aminothiophenol is 1 mol: 1-1.5 mol: 1 mL: 1-1.5 mol.

[0012] As a further preferred embodiment of the present invention, the purification operation of step 3) is as follows: after the reaction product is naturally cooled to 25°C-30°C, 3-5 times the volume of N'N-dimethylformamide and deionized water are added for suction filtration, and the product is washed with deionized water for 3-5 times, and then vacuum dried; thereafter, it is purified by column silica gel chromatography, the solvent is removed by a rotary evaporator, and vacuum dried again.

[0013] As a further preferred embodiment of the present invention, the chromatography liquid for chromatography purification is a mixture of petroleum ether and dichloromethane, and the mixed volume ratio of the two is 10:1.

[0014] The 2-(2'-hydroxyphenyl)-benzothiazole is prepared by the method.

[0015] In a second aspect of the present invention, the present invention discloses the use of 2-(2'-hydroxyphenyl)-benzothiazole in the preparation of resistive random access memory.

[0016] As a further preferred embodiment of the present invention, the resistive random access memory comprises an ITO layer, an organic active layer, and a top electrode from bottom to top, wherein the organic active layer is HBT; and the top electrode is Al or Au.

[0017] The present invention also discloses a method for preparing a resistive memory device using 2-(2'-hydroxyphenyl)-benzothiazole, comprising the following steps:

[0018] S1. Cleaning ITO conductive glass

[0019] The ITO glass was ultrasonically cleaned with distilled water and detergent, and then ultrasonically cleaned with acetone, anhydrous ethanol and distilled water in sequence. Each time the cleaning solvent was changed, it was first ultrasonically cleaned with distilled water; after cleaning, it was dried;

[0020] S2. Preparation of organic active layer

[0021] Place the treated glass sheet with the ITO surface facing upward on a desktop coating machine, drop the organic solution containing HBT on the ITO surface to soak the entire ITO surface, and then perform spin coating and annealing operations;

[0022] S3. Evaporation of metal top electrode: The sample with the spin-coated organic active layer is fixedly placed on a substrate with a mask plate. After turning on the cooling circulation system, the vent valve is opened until the air pressure in the vacuum evaporation chamber reaches atmospheric pressure. The door is opened to place the substrate in for evaporation of the metal top electrode.

[0023] As a further preferred embodiment of the present invention, in step 1), the ITO surface of the dried ITO glass is measured using an electric meter, and the ITO surface is placed in a plasma cleaning machine with the ITO surface facing upward to perform plasma cleaning on the ITO surface.

[0024] As a further preferred embodiment of the present invention, the concentration of HBT in the organic solution containing HBT is 12 mg / mL.

[0025] As further preferred embodiment of the present invention, the organic solvent is selected from one or a mixture of two or more of chlorobenzene, o-dichlorobenzene, dimethyl sulfoxide and N'N-dimethylformamide.

[0026] As a further preferred embodiment of the present invention, the spin coating is divided into two times, wherein the spin coating I is: the spin coating speed is 300-500 r / min, and the time is 6 s; the spin coating II is the spin coating speed is 1500-2500 r / min, and the time is 30-60 s; the annealing temperature is 60-80° C., and the annealing time is 30 min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The method of the present invention is used to synthesize 2-(2'-hydroxyphenyl)-benzothiazole HBT with a high yield of up to 72%;

[0029] 2. The organic molecular raw materials used in the synthesis of the present invention are cheap, the synthesis steps are simple, and the synthesis conditions are easy to achieve. Salicylaldehyde and 2-aminothiophenol can be used to synthesize HBT through a one-step reaction, which is conducive to industrial production;

[0030] 2. The resistive switching memory device prepared by using the 2-(2'-hydroxyphenyl)-benzothiazole of the present invention has better resistive switching performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 It is phenol and its derivatives;

[0033] Figure 2 It is a schematic diagram of the synthetic route of 2-(2'-hydroxyphenyl)benzothiazole;

[0034] Figure 3 It is the HBT molecular H NMR spectrum;

[0035] Figure 4 The fluorescence emission spectra of HBT molecules in water, anhydrous ethanol, dichloromethane, and toluene (a) and the enlarged image (b);

[0036] Figure 5 It is the IV characteristic curve of Al / HBT / ITO device under different process conditions;

[0037] Figure 6 It is the IV characteristic curve of Au / HBT / ITO device;

[0038] Figure 7 It is the IV characteristic curve of Al / MBT / ITO device;

[0039] Figure 8 This is a schematic diagram of the IV linear relationship fitting of the Al / HBT / ITO device in the low resistance state. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below in conjunction with specific implementation methods.

[0041] The room temperature in the present invention refers to 20-30°C, preferably 25°C.

[0042] Example 1

[0043] Synthesis of 2-(2'-hydroxyphenyl)-benzothiazole, refer to Figure 2 As shown, the following steps are included:

[0044] 1) Add sodium metabisulfite (3.80 g, 20 mmol), salicylaldehyde (2.44 g, 20 mmol) and N'N-dimethylformamide (20 mL) into a 100 mL Schlenk bottle and stir to dissolve;

[0045] 2) Add 2-aminobenzenethiol (2.51 g, 20 mmol) to the above reaction solution, and reflux at 153-155° C. for 8 h under argon protection;

[0046] 3) After the reaction was completed, the mixture was naturally cooled to room temperature, 60 mL of deionized water was added for filtration, and the mixture was washed three times with deionized water and dried under vacuum at 60° C. The mixture was purified by column silica gel chromatography (petroleum ether: dichloromethane = 10:1), the solvent was removed by a rotary evaporator, and the mixture was dried in a vacuum oven to obtain 3.28 g of a white solid with a yield of 72%.

[0047] Example 2

[0048] The synthesis of 2-(2'-hydroxyphenyl)-benzothiazole comprises the following steps:

[0049] 1) Add sodium metabisulfite (3.80 g, 20 mmol), salicylaldehyde (2.44 g, 20 mmol) and dimethyl sulfoxide (20 mL) into a 100 mL Schlenk bottle and stir to dissolve;

[0050] 2) Add 2-aminobenzenethiol (2.51 g, 20 mmol) to the above reaction solution, and reflux at 189-191°C for 8 h under argon protection;

[0051] 3) After the reaction was completed, the mixture was naturally cooled to room temperature, 60 mL of deionized water was added for filtration, and the mixture was washed three times with deionized water and dried under vacuum at 60° C. The mixture was purified by column silica gel chromatography (petroleum ether: dichloromethane = 10:1), the solvent was removed by a rotary evaporator, and the mixture was dried in a vacuum oven to obtain 3.19 g of a white solid with a yield of 70%.

[0052] Comparative Example 1 Effect of Replacing N'N-dimethylformamide with Ethanol on Yield

[0053] The synthesis of 2-(2'-hydroxyphenyl)-benzothiazole comprises the following steps:

[0054] 1) Add sodium metabisulfite (3.80 g, 20 mmol), salicylaldehyde (2.44 g, 20 mmol) and ethanol (20 mL) into a 100 mL Schlenk bottle and stir to dissolve;

[0055] 2) Add 2-aminobenzenethiol (2.51 g, 20 mmol) to the above reaction solution, and reflux at 120-122° C. for 8 h under argon protection;

[0056] 3) After the reaction was completed, the mixture was naturally cooled to room temperature, 60 mL of deionized water was added for filtration, and the mixture was washed three times with deionized water and dried under vacuum at 60° C. The mixture was purified by column silica gel chromatography (petroleum ether: dichloromethane = 10:1), the solvent was removed by a rotary evaporator, and the mixture was dried in a vacuum oven to obtain 2.37 g of a white solid with a yield of 52%.

[0057] Comparative Example 2 Effect of replacing sodium pyrosulfite with sodium bisulfite on yield

[0058] Synthesis of 2-(2'-hydroxyphenyl)-benzothiazole, refer to Figure 2 As shown, the following steps are included:

[0059] 1) Add sodium bisulfite (2.08 g, 20 mmol), salicylaldehyde (2.44 g, 20 mmol) and N'N-dimethylformamide (20 mL) into a 100 mL Schlenk bottle and stir to dissolve;

[0060] 2) Add 2-aminobenzenethiol (2.51 g, 20 mmol) to the above reaction solution, and reflux at 153-155° C. for 8 h under argon protection;

[0061] 3) After the reaction was completed, the mixture was naturally cooled to room temperature, 60 mL of deionized water was added for filtration, and the mixture was washed three times with deionized water and dried under vacuum at 60° C. The mixture was purified by column silica gel chromatography (petroleum ether: dichloromethane = 10:1), the solvent was removed by a rotary evaporator, and the mixture was dried in a vacuum oven to obtain 1.28 g of a white solid with a yield of 28%.

[0062] Sodium bisulfite is easily decomposed, and using sodium bisulfite as a catalyst leads to a decrease in the reaction yield.

[0063] Application ExampleAS

[0064] Application example AS uses 2-(2'-hydroxyphenyl)-benzothiazole to prepare a resistive memory device, including the following steps:

[0065] S1. Cleaning ITO conductive glass: Use a glass cutter to cut the ITO glass into 1.5cm×1.5cm and 2cm×2cm glass blocks, place the cut ITO glass on a cleaning rack in a beaker, add distilled water and detergent to ultrasonically clean for 30 minutes, then use a cotton swab dipped in detergent to repeatedly scrub the ITO glass, then clean it with distilled water, put it on the cleaned cleaning rack, add distilled water to ultrasonically clean for 5 minutes, and then use acetone, anhydrous ethanol and distilled water to ultrasonically clean for 30 minutes in turn. Each time the solvent used for cleaning is changed, distilled water ultrasonic cleaning is required for 5 minutes. After cleaning, put it in a blast oven at 80°C and dry it for 1 hour. Use an ammeter to measure the ITO surface of the dried ITO glass, put the ITO side facing up into a plasma cleaning machine, and after vacuuming for 15 minutes, start the program to plasma clean the ITO surface for 5 minutes to increase the wettability of the ITO surface, which is beneficial to the subsequent spin coating process of the active layer;

[0066] S2. Preparation of organic active layer: Place the treated glass sheet with the ITO surface facing upward on a desktop coating machine and turn on the vacuum oil pump to fix it. Use a pipette to absorb the HBT organic material solution and drop it on the ITO surface. Let it stand for 30 seconds to allow the solution to evenly spread and soak the entire ITO surface. Then perform spin coating and annealing operations. The spin coating and annealing parameters are shown in Table 1:

[0067] The preparation method of HBT organic material solution is as follows:

[0068] A: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of chlorobenzene solvent to obtain a 12 mg / mL HBT molecule chlorobenzene solution for preparing the memory;

[0069] B: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of o-dichlorobenzene solvent to obtain a 12 mg / mL o-dichlorobenzene solution of HBT molecules for preparing the memory;

[0070] C: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of toluene solvent to obtain a 12 mg / mL toluene solution of HBT molecules for preparing the memory;

[0071] D: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of dimethyl sulfoxide solvent to obtain a 12 mg / mL dimethyl sulfoxide solution of HBT molecules for preparing the memory;

[0072] E: 12.0 mg of HBT molecules were weighed and dissolved in 1 mL of N'N-dimethylformamide solvent to obtain a 12 mg / mL N'N-dimethylformamide solution of HBT molecules for preparing a memory.

[0073] Table 1 Al / HBT / ITO device process conditions

[0074]

[0075]

[0076] S3. Evaporation of metal top electrode: Place the sample with spin-coated organic active layer on the substrate with mask, open the cooling circulation system, open the vent valve until the pressure in the vacuum evaporation chamber reaches atmospheric pressure, open the door and put the substrate in. Grind the metal Al wire with sandpaper, cut it into particles of about 2 mm, put it in the tungsten boat fixed in the vacuum evaporation chamber, and close the door. Evacuate the entire evaporation system: Open the mechanical pump and the fore-stage valve, and reduce the vacuum in the fore-stage chamber to 1×10 -1 Pa; close the fore valve, open the bypass valve, and reduce the bypass chamber vacuum to 7×10 -1 Pa; open the fore-stage valve, substrate rotation, and molecular pump main valve to reduce the vacuum of the fore-stage chamber to 5.5×10-4 Pa, reaching the target vacuum of the evaporation system. Open the FTM-V module and set the evaporation sample type and thickness to Al: Turn on the TPRE-Z20-IV module, press the start button, and observe the voltage, current, and evaporation rate on the FTM V module display. Turn the "current adjustment" to increase the current. When the current is less than 120A, the current increase rate is 5A / min; when the current is greater than 120A, the current increase rate is 2.5A / min. When the evaporation rate is stable, reset the film parameters to zero, open the substrate baffle and start evaporation. After the evaporation is completed, close the substrate baffle, adjust the current to 0, and turn off the TPRE-Z20-IV module, FTM-V module, main valve, and molecular pump in turn. Wait for the molecular pump frequency to drop to 0Hz, and continue to close the fore valve, mechanical pump, substrate rotation, power supply, and cooling system. Let it cool, open the vent valve to remove the sample, and clean the discarded tungsten boat and evaporation chamber. After taking out the sample, the evaporation instrument needs to be evacuated to a vacuum state again.

[0077] Experimental Example 1: Fluorescence emission spectrum test of HBT in different solvents

[0078] Preparation of fluorescence test solutions of 2-(2'-hydroxyphenyl)-benzothiazole in different solvents: 1.29 mg of HBT molecules were weighed and dissolved in 5.68 mL of dimethyl sulfoxide (DMSO) organic solvent to prepare a 1 mmol / L stock solution.

[0079] A: Use a 1000-5000μL pipette to add 3mL of deionized water into the cuvette, use a 20-200μL pipette to add 30μL of the mother solution into the cuvette, and use a 1mL dropper to mix the solution evenly to obtain an aqueous solution of HBT molecules, recorded as HBT-H 2 O;

[0080] B: Use a 1000-5000 μL pipette to add 3 mL of anhydrous ethanol into the cuvette, use a 20-200 μL pipette to add 30 μL of the mother solution into the cuvette, and use a 1 mL dropper to mix the solution evenly to obtain an anhydrous ethanol solution of HBT molecules, recorded as HBT-EtOH;

[0081] C: Use a 1000-5000 μL pipette to add 3 mL of dichloromethane into the cuvette, use a 20-200 μL pipette to add 30 μL of the mother solution into the cuvette, and use a 1 mL dropper to mix the solution evenly to obtain a dichloromethane solution of HBT molecules, recorded as HBT-DCM;

[0082] D: Use a 1000-5000 μL pipette to add 3 mL of toluene into the cuvette, use a 20-200 μL pipette to add 30 μL of the mother solution into the cuvette, and use a 1 mL dropper to mix the solution evenly to obtain a toluene solution of HBT molecules, recorded as HBT-PhMe.

[0083] The fluorescence emission spectra of HBT molecules in different solvents were tested and the molecular conformation changes of HBT were analyzed. The results are as follows: Figure 4 shown.

[0084] Figure 4 It is the fluorescence emission spectrum of HBT molecules in water, anhydrous ethanol, dichloromethane and toluene. Since there is an excited state intramolecular proton transfer process in HBT molecules, the solvent will have a significant effect on the hydrogen bonding effect in HBT molecules. By testing the fluorescence emission spectra of HBT in different solvents, it can be seen that HBT molecules have two structures: keto structure and enol structure. In aprotic solvents, solvent molecules will not interfere with the hydrogen bond between the nitrogen atom of the benzothiazole ring and the proton of the phenolic hydroxyl group. HBT molecules exist more in keto structure. After laser excitation, the fluorescence emission of the keto structure is caused at 520nm. In protic solvents, since the nitrogen atom of the benzothiazole ring of the HBT molecule is combined with the proton on the solvent molecule, the HBT molecule is mainly in the enol structure, and its keto structure fluorescence emission peak is greatly reduced. The molecule causes fluorescence emission in the enol structure at 400nm. In addition, when the HBT molecule is in water, the keto structure and the enol structure fluorescence emission exist simultaneously, and its fluorescence intensity is much greater than that in organic solvents, and its emission wavelength is between the keto structure fluorescence emission wavelength and the enol structure fluorescence emission wavelength.

[0085] Experimental Example 2: HBT device testing prepared under different process conditions

[0086] The Al / HBT / ITO devices prepared under different process conditions in the corresponding case AS were tested for IV. The results are as follows Figure 5 And as shown in Table 2.

[0087] Table 2 Comparison of switching ratios of Al / HBT / ITO devices prepared under different process conditions

[0088] Serial number ON / OFF ratio A <![CDATA[6.11×10 4 ]]> B <![CDATA[1.00×10 6 ]]> C 19.80 D <![CDATA[6.29×10 7 ]]> E <![CDATA[1.94×10 8 ]]> F 71.00 G <![CDATA[2.96×10 2 ]]> H <![CDATA[4.53×10 2 ]]> I <![CDATA[1.39×10 3 ]]> J <![CDATA[1.51×10 3 ]]> K <![CDATA[2.57×10 4 ]]> L <![CDATA[3.99×10 5 ]]> M <![CDATA[4.58×10 5 ]]> N <![CDATA[3.54×10 5 ]]> O <![CDATA[6.17×10 3 ]]> P <![CDATA[2.53×10 6 ]]> Q <![CDATA[1.47×10 5 ]]> R <![CDATA[1.56×10 4 ]]> S <![CDATA[2.97×10 8 ]]>

[0089] from Figure 5 From the results in Table 2, it can be seen that the best process condition for obtaining HBT molecular devices is S, that is, the speed of coating I is 500r / min, the coating time is 6s, the speed of coating II is 2500r / min, the coating time is 60s, the annealing temperature is 80℃, and the annealing time is 30min. Under the best process conditions, the device switching ratio can be as high as 10 8, which has broad application prospects.

[0090] Experimental Example 3: Exploration of the resistive switching mechanism of Al / HBT / ITO devices

[0091] In order to explore the resistive switching mechanism of Al / HBT / ITO devices, Au / HBT / ITO was prepared and Al / MBT / ITO devices were prepared with 2-(2'-methoxyphenyl)benzothiazole which does not have intramolecular hydrogen bonds.

[0092] The preparation method of Au / HBT / ITO is the same as that of Al / HBT / ITO device, except that the metal top electrode is replaced by Au.

[0093] The preparation method of the Al / MBT / ITO device is the same as that of the Al / HBT / ITO device, except that the HBT is replaced by MBT.

[0094] The IV characteristics of Au / HBT / ITO and Al / MBT / ITO devices were tested, and the results are shown in Figure 6 and Figure 7 shown.

[0095] Figure 6 This is the IV characteristic curve of Au / HBT / ITO device. Figure 6 The results show that after the metal top electrode is replaced with Au, the device still exhibits resistive switching behavior, which indicates that the device resistive switching is not caused by the Al electrode entering the active layer to form metal filaments.

[0096] Figure 7 This is the IV characteristic curve of the Al / MBT / ITO device. Figure 7 It can be seen that the Al / MBT / ITO device does not exhibit resistive switching behavior within the voltage scanning range of -4V to 4V specified by the instrument, which indicates that only HBT molecules with intramolecular hydrogen bonds have resistive switching properties.

[0097] Figure 8 This is a schematic diagram of the IV linear relationship fitting of the Al / HBT / ITO device in the low resistance state. In the low resistance state, the voltage applied to the device is linearly related to the current passing through the device, that is, in the low resistance state, the Al / HBT / ITO device follows Ohm's law, so there is no potential barrier and charge capture center in the device.

[0098] In summary, the resistive switching process of the Al / HBT / ITO device is as follows: In the initial state, the HBT molecules in the active layer are in an enol structure with intramolecular hydrogen bonds. Under the action of an external electric field, the protons of the phenolic hydroxyl groups are transferred to the N atom through hydrogen bonds to form a keto structure, which reduces the molecular energy band gap. As the voltage increases, the charge at the HOMO energy level of the molecule is excited to transition to the LUMO energy level, and the device changes from a high-resistance state to a low-resistance state. When a reverse voltage is applied, the protons gradually deflect back to the oxygen atoms, the molecules change from the keto form back to the enol form, and the device returns to a high-resistance state.

[0099] Experimental Example 4: Resistance switching performance test of resistive switching devices prepared by other organic molecules with intramolecular hydrogen bonds

[0100] Resistive switching devices are prepared using different organic molecules with intramolecular hydrogen bonds, and the preparation process refers to the application examples.

[0101] A: Use 2-(2-hydroxyphenyl)pyrrole as the organic active layer material to prepare a resistive switching device and test its resistive switching performance;

[0102] B: Using 2-(2-hydroxyphenyl)imidazole as the organic active layer material to prepare a resistive switching device and test its resistive switching performance;

[0103] C: Using 2-(2-hydroxyphenyl)thiazole as the organic active layer material to prepare a resistive switching device and test its resistive switching performance;

[0104] D: Using 2-(2-hydroxyphenyl)pyridine as the organic active layer material to prepare a resistive switching device and test its resistive switching performance;

[0105] E: Using 2-(2-hydroxyphenyl)pyrimidine as the organic active layer material to prepare a resistive switching device and test its resistive switching performance;

[0106] F: A resistive switching device was prepared using 2-(1,3,5-triazine-2-yl)phenol as an organic active layer material, and its resistive switching performance was tested.

[0107] The resistive switching performance of devices prepared with different organic molecules is shown in Table 3.

[0108] Table 3 Comparison of switching ratios of devices prepared with different organic molecules

[0109] Serial number ON / OFF ratio A <![CDATA[1.70×10 4 ]]> B <![CDATA[4.29×10 4 ]]> C <![CDATA[1.03×10 5 ]]> D <![CDATA[4.07×10 4 ]]> E <![CDATA[2.17×10 5 ]]> F <![CDATA[7.32×10 4 ]]>

[0110] From the results in Table 3, we can see that the highest switching ratio of devices prepared by using other organic molecules is 2.17×10 5 , has certain resistance switching performance, but not as good as the device of the present invention, the switching ratio can be as high as 10 8The reason is analyzed as follows: the molecular resistive switching performance is jointly affected by the molecular conjugation length and planarity. The growth of conjugation is beneficial to the charge transfer in the molecular ground state, and the switching ratio is reduced; good planarity in the excited state is beneficial to the charge transfer in the ON state, thereby improving the resistive switching performance.

[0111] The preferred embodiments of the present invention are specifically described above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are all within the scope defined by the claims of this application. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for synthesizing 2-(2'-hydroxyphenyl)-benzothiazole, characterized in that: The following steps are involved: 1) Stir and dissolve sodium metabisulfite, salicylaldehyde and N'N-dimethylformamide; 2) adding 2-aminothiophenol to the above reaction solution, and refluxing at 153-191° C. under protective gas protection; 3) After the reaction is completed, the mixture is cooled naturally and purified to obtain a white solid.

2. The method for synthesizing 2-(2'-hydroxyphenyl)-benzothiazole according to claim 1, characterized in that: The usage ratio of the sodium pyrosulfite, salicylaldehyde, N'N-dimethylformamide and 2-aminothiophenol is 1 mol: 1-1.5 mol: 1 mL: 1-1.5 mol.

3. The method for synthesizing 2-(2'-hydroxyphenyl)-benzothiazole according to claim 1, characterized in that: The purification operation of step 3) is as follows: after the reaction product is naturally cooled to 25°C-30°C, 3-5 times the volume of N'N-dimethylformamide and deionized water are added for filtration, and after washing with deionized water for 3-5 times, vacuum drying is performed; then, column silica gel chromatography is used for purification, a rotary evaporator is used to remove the solvent, and vacuum drying is performed again.

4. The method for synthesizing 2-(2'-hydroxyphenyl)-benzothiazole according to claim 3, characterized in that: The chromatographic liquid for chromatographic purification is a mixture of petroleum ether and dichloromethane, and the volume ratio of the two is 10:

1.

5. 2-(2'-Hydroxyphenyl)-benzothiazole prepared by the method according to any one of claims 1 to 4.

6. Application of 2-(2'-hydroxyphenyl)-benzothiazole in the preparation of resistive random access memory.

7. The use according to claim 6, characterized in that: The resistive random access memory comprises an ITO layer, an organic active layer and a top electrode from bottom to top, wherein the organic active layer is HBT; and the top electrode is Al or Au.

8. A method for preparing a resistive memory device using 2-(2'-hydroxyphenyl)-benzothiazole, characterized in that: The following steps are involved: S1. Cleaning ITO conductive glass After ultrasonic cleaning of the ITO glass with distilled water and detergent, ultrasonic cleaning is performed with acetone, anhydrous ethanol and distilled water in sequence. Each time the cleaning solvent is changed, ultrasonic cleaning with distilled water is performed first; washing and drying are performed; S2. Preparation of organic active layer Place the treated glass sheet with the ITO surface facing upward on a desktop coating machine, drop the organic solution containing HBT on the ITO surface to soak the entire ITO surface, and then perform spin coating and annealing operations; S3. Evaporation of metal top electrode The sample with the organic active layer spin-coated is fixedly placed on a substrate with a mask plate. After turning on the cooling circulation system, the vent valve is opened until the air pressure in the vacuum evaporation chamber reaches atmospheric pressure. The door is opened to place the substrate in for evaporation of the metal top electrode.

9. The method for preparing a resistive memory device Al / HBT / ITO according to claim 8, characterized in that: In step 1), the ITO surface of the dried ITO glass is measured using an ammeter, and the ITO surface is placed in a plasma cleaning machine with the ITO side facing up to perform plasma cleaning on the ITO surface; in step S2, the concentration of HBT in the organic solution containing HBT is 12 mg / mL; the organic solution is selected from one or a mixture of two or more of chlorobenzene, o-dichlorobenzene, dimethyl sulfoxide and N'N-dimethylformamide.

10. The method for preparing a resistive memory device Al / HBT / ITO according to claim 8, characterized in that: The spin coating is divided into two times, wherein the spin coating I is: the spin coating speed is 300-500 r / min, and the time is 6 s; the spin coating II is: the spin coating speed is 1500-2500 r / min, and the time is 30-60 s; the annealing temperature is 60-80° C., and the annealing time is 30 min.

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