A 2-(2'-hydroxyphenyl)-benzothiazole, its synthesis method, and its application in the preparation of resistive switching memory.

Abstract

This invention discloses a 2-(2'-hydroxyphenyl)-benzothiazole and its synthesis method. It can be synthesized by a one-step reaction of salicylaldehyde and 2-aminobenzylthiophenol, with high yield and low cost of organic molecular raw materials. The synthesis steps are simple and easy to industrialize. At the same time, the 2-(2'-hydroxyphenyl)-benzothiazole of this invention can be used to prepare resistive switching memory devices with better resistive switching performance.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and resistive switching memory device preparation technology, specifically relating to the synthesis method of 2-(2'-hydroxyphenyl)-benzothiazole (HBT) and its application in the preparation of resistive switching memory. Background Technology

[0002] In recent years, inorganic resistive switching memory (RSM) technology has matured, but its room for improvement is limited. Furthermore, inorganic materials have poor flexibility, which, with the development of computer technology, can no longer meet the demands for flexible wearable devices. Organic molecules, on the other hand, can be designed to introduce electron donors or acceptors into their molecular structure, allowing for flexible control of the resistive switching properties. Organic RSM has attracted widespread attention due to its advantages such as low manufacturing cost, simple process, flexibility, high performance, ease of processing, and controllability, making it a popular candidate for next-generation resistive switching materials. However, despite the numerous organic molecules already applied to RSM, the resistive switching mechanism of organic molecules remains inconclusive. Currently, the scientific community has proposed models for the resistive switching mechanism of organic RSM, including charge transfer, conformational change, charge trapping and release, and conductive filaments.

[0003] Organic molecules with intramolecular hydrogen bonds, such as phenols and their derivatives with linked heterocycles, etc. Figure 1 As shown, it has at least two molecular structures due to the presence of intramolecular hydrogen bonds. Different molecular structures have different electrical properties, thus making it a potential material for the active layer of resistive switching memory.

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

[0005] The purpose of this invention is to provide 2-(2'-hydroxyphenyl)-benzothiazole (HBT) and its synthesis method. Another objective is to provide the application of 2-(2'-hydroxyphenyl)-benzothiazole (HBT) in the fabrication of resistive switching memory (RSM) and the fabrication of related devices. Based on the HBT molecule, a class of small organic molecules with intramolecular hydrogen bonds are synthesized. By testing the resistive switching performance of this series of molecules, it is demonstrated that a class of organic molecules with intramolecular hydrogen bonds has the potential for application in resistive switching memory, among which HBT exhibits the most significant resistive switching effect.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

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

[0008] 1) Dissolve sodium metabisulfite, salicylaldehyde, and N,N-dimethylformamide by stirring;

[0009] 2) Add 2-aminothiophenol to the above reaction solution and reflux at 153-191℃ under protective gas;

[0010] 3) After the reaction is complete, the mixture is allowed to cool naturally and then purified to obtain a white solid.

[0011] As a further preferred embodiment of the present invention, the ratio of 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 in step 3) is as follows: after the reaction product is naturally cooled to 25℃-30℃, 3-5 times the volume of deionized water of N'N-dimethylformamide is added for filtration, and the product is washed with deionized water 3-5 times and then dried under vacuum; then purified by column silica gel chromatography, the solvent is removed by rotary evaporator, and then dried under vacuum again.

[0013] As a further preferred embodiment of the present invention, the chromatographic solvent for purification is a mixture of petroleum ether and dichloromethane, with a volume ratio of 10:1.

[0014] 2-(2'-hydroxyphenyl)-benzothiazole was prepared using the method described above.

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

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

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

[0018] S1. Cleaning ITO conductive glass

[0019] After ultrasonic cleaning with distilled water and detergent, ITO glass is ultrasonically cleaned in sequence with acetone, anhydrous ethanol and distilled water. Each time the cleaning solvent is changed, ultrasonic cleaning with distilled water must be performed first. After cleaning, it is dried.

[0020] S2, Preparation of the organic active layer

[0021] Place the prepared glass slide with the ITO side facing up on a benchtop spin coater, drop an organic solution containing HBT onto the ITO surface to wet the entire ITO surface, and then perform spin coating and annealing operations.

[0022] S3. For the evaporation of the metal top electrode, the sample with the spin-coated organic active layer is fixed on the substrate with the mask. 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 chamber door is then opened and the substrate is placed in for the evaporation of the metal top electrode.

[0023] As a further preferred embodiment of the present invention, in step 1), the dried ITO glass is measured with a multimeter to determine the ITO surface, and the ITO-side up is placed into a plasma cleaner 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 a further preferred embodiment of the present invention, the organic solution 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 performed in two stages, wherein spin coating I is performed at a spin speed of 300-500 r / min for 6 s; spin coating II is performed at a spin speed of 1500-2500 r / min for 30-60 s; the annealing temperature is 60-80℃ 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 this invention can synthesize 2-(2'-hydroxyphenyl)-benzothiazole HBT with a high yield, reaching 72%;

[0029] 2. The organic molecular raw materials used in the synthesis of this invention are inexpensive, and the synthesis steps are simple and the synthesis conditions are easy to achieve. HBT can be synthesized from salicylaldehyde and 2-aminothiophenol in one step, which is beneficial for industrial production.

[0030] 2. The resistive switching memory device prepared using 2-(2'-hydroxyphenyl)-benzothiazole of the present invention has better resistive switching performance. Attached Figure Description

[0031] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. 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 creative effort.

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

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

[0034] Figure 3 It is the hydrogen nuclear magnetic resonance spectrum of the HBT molecule;

[0035] Figure 4 The fluorescence emission spectra of HBT molecules in water, anhydrous ethanol, dichloromethane, and toluene are shown in (a) and magnified (b).

[0036] Figure 5 These are the IV characteristic curves of Al / HBT / ITO devices under different process conditions;

[0037] Figure 6 These are the IV characteristic curves of Au / HBT / ITO devices;

[0038] Figure 7 These are the IV characteristic curves of Al / MBT / ITO devices;

[0039] Figure 8 This is a schematic diagram of the linear relationship fitting of IV for Al / HBT / ITO devices in the low-resistivity state. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with specific embodiments.

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

[0042] Example 1

[0043] The synthesis of 2-(2'-hydroxyphenyl)-benzothiazole is described in reference [reference needed]. Figure 2 As shown, it includes the following steps:

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

[0045] 2) Add 2-aminothiophenol (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 allowed to cool naturally to room temperature. 60 mL of deionized water was added and the mixture was filtered. The solution was washed three times with deionized water and dried under vacuum at 60 °C. The mixture was purified by column chromatography with silica gel (petroleum ether: dichloromethane = 10:1), the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain 3.28 g of white solid, with a yield of 72%.

[0047] Example 2

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

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

[0050] 2) Add 2-aminothiophenol (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 allowed to cool naturally to room temperature. 60 mL of deionized water was added and the mixture was filtered. The mixture was washed three times with deionized water and dried under vacuum at 60 °C. The mixture was purified by column chromatography with silica gel (petroleum ether: dichloromethane = 10:1), the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain 3.19 g of white solid, with a yield of 70%.

[0052] Effect of replacing N'N-dimethylformamide with ethanol on the yield in Comparative Example 1

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

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

[0055] 2) Add 2-aminothiophenol (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 allowed to cool naturally to room temperature. 60 mL of deionized water was added and the mixture was filtered. The mixture was washed three times with deionized water and dried under vacuum at 60 °C. The mixture was purified by column chromatography with silica gel (petroleum ether: dichloromethane = 10:1), the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain 2.37 g of white solid, with a yield of 52%.

[0057] Comparative Example 2: Effect of Replacing Sodium Metabisulfite with Sodium Bisulfite on Yield

[0058] The synthesis of 2-(2'-hydroxyphenyl)-benzothiazole is described in reference [reference needed]. Figure 2 As shown, it includes the following steps:

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

[0060] 2) Add 2-aminothiophenol (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 allowed to cool naturally to room temperature. 60 mL of deionized water was added and the mixture was filtered. The mixture was washed three times with deionized water and dried under vacuum at 60 °C. The mixture was purified by column chromatography with silica gel (petroleum ether: dichloromethane = 10:1), the solvent was removed by rotary evaporation, and the mixture was dried under vacuum to obtain 1.28 g of 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 reaction yield.

[0063] Application example AS

[0064] Application example AS utilizes 2-(2'-hydroxyphenyl)-benzothiazole to prepare resistive switching memory devices, including the following steps:

[0065] S1. Cleaning ITO conductive glass: Cut the ITO glass into 1.5cm×1.5cm and 2cm×2cm pieces using a glass cutter. Place the cut ITO glass on a cleaning rack in a beaker, add distilled water and detergent, and ultrasonically clean for 30 minutes. Then, use a cotton swab dipped in detergent to repeatedly rub the ITO glass, rinse it clean with distilled water, place it on a clean cleaning rack, add distilled water, and ultrasonically clean for 5 minutes. Then, use acetone, anhydrous ethanol, and distilled water sequentially for ultrasonic cleaning for 30 minutes each time. Each time the cleaning solvent is changed, ultrasonic cleaning with distilled water for 5 minutes is required. After cleaning, place it in a forced-air drying oven at 80℃ for 1 hour. Use a multimeter to measure the ITO surface of the dried ITO glass, place it with the ITO side facing up in a plasma cleaner, evacuate for 15 minutes, and then start the program to perform plasma cleaning on the ITO surface for 5 minutes to increase the wettability of the ITO surface, which is beneficial for the subsequent spin coating process of the active layer.

[0066] S2. Preparation of the organic active layer: Place the treated glass slide with the ITO side facing up on a benchtop spin coater and turn on the vacuum pump to fix it. Use a pipette to draw HBT organic material solution and drop it onto the ITO surface. Let it stand for 30 seconds to allow the solution to evenly spread and wet 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 chlorobenzene solution with 12 mg / mL HBT molecules for use in the preparation of memory.

[0069] B: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of o-dichlorobenzene solvent to obtain an o-dichlorobenzene solution with 12 mg / mL HBT molecules for use in the preparation of memory.

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

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

[0072] E: Weigh 12.0 mg of HBT molecules and dissolve them in 1 mL of N'N-dimethylformamide solvent to obtain an N'N-dimethylformamide solution with 12 mg / mL HBT molecules for use in the preparation of memory.

[0073] Table 1. Process conditions for Al / HBT / ITO devices

[0074]

[0075]

[0076] S3. Evaporation of the metal top electrode: The sample with the spin-coated organic active layer is fixed on a substrate with a mask. 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 chamber door is then opened and the substrate is placed inside. The Al metal wire is sanded with sandpaper, cut into particles of approximately 2mm, and placed into the tungsten boat already fixed in the vacuum evaporation chamber. The chamber door is then closed. The entire evaporation system is evacuated to a vacuum: the mechanical pump and the fore-stage valve are turned on, reducing the vacuum in the fore-stage chamber to 1×10⁻⁶. -1 Pa; Close the fore-stage valve, open the bypass valve, and reduce the vacuum in the bypass chamber to 7 × 10⁻⁶. -1 Below Pa; open the forestage valve, substrate rotation, and molecular pump main valve to reduce the vacuum in the forestage chamber to 5.5 × 10⁻⁶ Pa.-4 Below Pa, the target vacuum level of the vapor deposition system is reached. Open the FTM-V module and set the 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 displayed on the FTM V module screen. Increase the current by rotating the "Current Adjustment" knob. When the current is less than 120A, the current increase rate should be 5A / min; when the current is greater than 120A, the current increase rate should be 2.5A / min. Once the evaporation rate stabilizes, reset the film parameters to zero and open the substrate baffle to begin evaporation. After evaporation, close the substrate baffle, adjust the current to 0, and sequentially turn off the TPRE-Z20-IV module, FTM-V module, main valve, and molecular pump. Wait for the molecular pump frequency to drop to 0Hz, then continue to turn off the fore-stage valve, mechanical pump, substrate rotation, power supply, and cooling system. Allow the system to cool, open the vent valve to remove the sample, and clean the waste tungsten boat and evaporation chamber. After removing the sample, the evaporation instrument must be evacuated to a vacuum state again.

[0077] Experimental Example 1: Fluorescence Emission Spectroscopy 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 to a cuvette, use a 20-200μL pipette to add 30μL of the mother liquor to the cuvette, and use a 1mL dropper to mix the solution evenly to obtain an aqueous solution of HBT molecules, denoted as HBT-H2O.

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

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

[0082] D: Using a 1000-5000 μL pipette, add 3 mL of toluene to a cuvette. Using a 20-200 μL pipette, add 30 μL of the mother liquor to the cuvette. Use a 1 mL dropper to mix the solution thoroughly to obtain a toluene solution of HBT molecules, denoted as HBT-PhMe.

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

[0084] Figure 4 These are the fluorescence emission spectra of HBT molecules in water, anhydrous ethanol, dichloromethane, and toluene. Because of the intramolecular proton transfer process within the excited state of the HBT molecule, the solvent significantly affects the hydrogen bonding effect within the HBT molecule. Testing the fluorescence emission spectra of HBT in different solvents reveals that the HBT molecule exists in both keto and enol structures. In aprotic solvents, the solvent molecules do not interfere with the hydrogen bonds between the nitrogen atom of the benzothiazole ring and the proton of the phenolic hydroxyl group, and the HBT molecule is more predominantly in the keto structure, exhibiting fluorescence emission at 520 nm after laser excitation. However, in protic solvents, because the nitrogen atom of the benzothiazole ring in the HBT molecule binds to the protons on the solvent molecules, the HBT molecule is predominantly in the enol structure, with a significantly reduced fluorescence emission peak in the keto structure. The molecule then exhibits fluorescence emission at 400 nm in the enol structure. Furthermore, when HBT molecules are in water, both the keto and enol structures emit fluorescence simultaneously, and the fluorescence intensity is much greater than that in organic solvents. The emission wavelength is located between the fluorescence emission wavelengths of the keto and enol structures.

[0085] Experimental Example 2: Device Testing of HBT Fabricated Under Different Process Conditions

[0086] IV tests were performed on Al / HBT / ITO devices fabricated under different process conditions, corresponding to the use case AS. The results are as follows: Figure 5 As shown in Table 2.

[0087] Table 2 Comparison of on / off 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 As shown in Table 2, the optimal process conditions for fabricating HBT molecules are S, namely, a spindle speed of 500 r / min and a spindle time of 6 s for spindle I, a spindle speed of 2500 r / min and a spindle time of 60 s for spindle II, and an annealing temperature of 80℃ and an annealing time of 30 min. Under these optimal process conditions, the device on / off ratio can reach as high as 10. 8It has broad application prospects.

[0090] Experimental Example 3: Exploration of the Resistive Switching Mechanism of Al / HBT / ITO Devices

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

[0092] The fabrication method of Au / HBT / ITO is the same as that of Al / HBT / ITO devices, except that the metal top electrode is replaced with Au.

[0093] The fabrication method for Al / MBT / ITO devices is the same as that for Al / HBT / ITO devices, except that HBT is replaced with MBT.

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

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

[0096] Figure 7 These are the IV characteristic curves of Al / MBT / ITO devices. From... Figure 7 It can be seen that the Al / MBT / ITO device did not exhibit resistive switching behavior within the voltage scan range of -4V to 4V limited by the instrument, indicating that only HBT molecules with intramolecular hydrogen bonds possess resistive switching performance.

[0097] Figure 8 This is a schematic diagram of the linear IV relationship fitting for an Al / HBT / ITO device in the low-resistivity state. In the low-resistivity state, the voltage applied to the device is linearly related to the current flowing through it. That is, in the low-resistivity state, the Al / HBT / ITO device follows Ohm's law, so there are no potential barriers or charge trapping centers in the device.

[0098] In summary, the resistive switching process of the Al / HBT / ITO device is as follows: Initially, the HBT molecules in the active layer are in an enol structure with intramolecular hydrogen bonds. Under an applied electric field, the protons of the phenolic hydroxyl groups are transferred to the N atom via hydrogen bonding to form a keto structure, reducing the molecular band gap. As the voltage increases, the charge at the HOMO level is excited and transitions to the LUMO level, and the device transitions from a high-resistivity state to a low-resistivity state. When a reverse voltage is applied, the protons gradually shift back to the oxygen atom, the molecule changes from the keto structure back to the enol structure, and the device returns to the high-resistivity state.

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

[0100] Resistive switching devices are fabricated using different organic molecules with intramolecular hydrogen bonds. The fabrication process is described in the application examples.

[0101] A: A resistive switching device was fabricated using 2-(2-hydroxyphenyl)pyrrole as the organic active layer material, and its resistive switching performance was tested.

[0102] B: Use 2-(2-hydroxyphenyl)imidazolium 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, a resistive switching device was prepared, and its resistive switching performance was tested;

[0104] D: Use 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, a resistive switching device was prepared, and its resistive switching performance was tested;

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

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

[0108] Table 3 Comparison of on / off 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] As shown in Table 3, the highest on / off ratio for devices fabricated using other organic molecules is 2.17 × 10⁻⁶. 5 It has certain resistive switching performance, but not as high as the switching ratio of the device of this invention, which can reach 10. 8The reason for this is that the resistive switching performance of a molecule is affected by both the conjugation length and the planarity of the molecule. Increased conjugation length is beneficial for charge transport in the ground state of the molecule, which reduces the on / off ratio. Good planarity in the excited state is beneficial for charge transport in the ON state of the molecule, which improves the resistive switching performance.

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

Claims

Application of 1,2-(2'-hydroxyphenyl)-benzothiazole in the preparation of resistive switching memory.

2. The application according to claim 1, characterized in that, The resistive switching memory consists of an ITO layer, an organic active layer, and a top electrode from bottom to top. The organic active layer is HBT, and the top electrode is Al or Au.

3. The application according to claim 2, characterized in that, The top electrode is Al.

4. A method for preparing resistive switching memory devices using 2-(2'-hydroxyphenyl)-benzothiazole, characterized in that, Includes the following steps: S1. Cleaning ITO conductive glass: After ultrasonic cleaning of ITO glass with distilled water and detergent, use acetone, anhydrous ethanol and distilled water in sequence for ultrasonic cleaning. Each time the solvent used for cleaning is changed, distilled water must be used for ultrasonic cleaning first. Wash and dry thoroughly; S2. Preparation of the organic active layer: Place the treated glass slide with the ITO side facing up on a tabletop spin coater, drop an organic solution containing HBT onto the ITO surface to wet the entire ITO surface, and then perform spin coating and annealing operations. S3. For the evaporation of the metal top electrode, the sample with the spin-coated organic active layer is fixed on the substrate with the mask. 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 chamber door is then opened and the substrate is placed in for the evaporation of the metal top electrode.

5. The method for preparing resistive switching memory devices using 2-(2'-hydroxyphenyl)-benzothiazole according to claim 4, characterized in that, In step 1), the dried ITO glass is measured with a multimeter to determine the ITO surface, and the ITO side is placed in a plasma cleaner 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.

6. The method for preparing resistive switching memory devices using 2-(2'-hydroxyphenyl)-benzothiazole according to claim 4, characterized in that, Spin coating is performed in two stages, with spin coating I being: Spin coating speed 300-500 r / min, time 6 s; Spin coating II is performed at a spin speed of 1500-2500 r / min for 30-60 s. The annealing temperature is 60-80℃ and the annealing time is 30 minutes.

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