Nanometer memory for ultra-high density data storage and method of making same

Abstract

The application provides a nanometer memory for ultra-high density data storage and a preparation method thereof, wherein a receptor group is reasonably introduced into an amphiphilic block copolymer, micelles are self-assembled to form storage units, and the preparation of the nanometer memory is realized by arraying the micelles through the induction of a nanometer array substrate. The application has the advantages that the micelles self-assembled by the amphiphilic block copolymer are uniform in size, the obtained micelles can be regularly arrayed under the induction of the substrate, and the micelles in the substrate have good semiconductor characteristics and can be applied to the development of memory devices as nanometer storage units. Compared with traditional storage devices, the innovative method greatly reduces the size of the storage units and opens up a new way for the further development of ultra-high density data storage.

Description

Technical Field

[0001] This invention belongs to the technical field of functional design of organic semiconductor materials and development of novel memory devices. Specifically, it relates to the preparation of amphiphilic block copolymer materials, self-assembly to form micelles, preparation of substrate-induced nano-memory devices, and testing of semiconductor performance. Background Technology

[0002] The storage density of currently used storage devices is approximately 10. 6-8 bit / cm 2 , with 10 12 bit / cm 2 The requirements for ultra-high-density data storage differ by several orders of magnitude. Traditional device fabrication processes and materials are increasingly unable to meet the current technological demands for ultra-high storage density. With the development of science and technology, next-generation memory devices have even higher requirements, with many practical needs in devices such as mobile phones and computers, such as a significant reduction in working area and a significant increase in operating speed. Furthermore, the size of the storage device directly affects the design and composition of the entire device. In recent years, the common fabrication method for organic electronic storage devices is a sandwich structure of metal-organic active layer-metal. The size of the storage cells in this structure is still tens of micrometers, which still cannot meet the pursuit of ultra-high-density information storage.

[0003] Therefore, scientists are working to improve the data storage density of organic devices in two ways: firstly, by developing multi-level data storage devices to increase storage density from 2... n Increased to 3 n Or 4 n The first approach involves reducing the unit size from the micrometer to the nanometer scale. Since the first report on small molecule-based ternary devices in 2010, researchers have constructed dozens of small molecule and polymer multilevel memory devices guided by intramolecular / intermolecular charge transfer, conformational changes, and charge trapping mechanisms. Among these, polymer materials have advantages such as ease of processing, spin coating, and functional tunability, making them even suitable for constructing high-density memory devices. However, the size of the memory units is relatively large and they are mainly binary. Therefore, how to design a novel functional polymer to self-assemble into nanoscale memory units is a key issue for further improving the storage density of ternary data. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing nano-memory devices. The method involves rationally introducing donor and acceptor groups into an amphiphilic block copolymer, which self-assembles into micelles as storage units. The arraying of these micelles is then induced by a nanoarray substrate to achieve the fabrication of the nano-memory device.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A nano-memory for ultra-high density data storage includes a conductive substrate and nano-memory cells on the substrate; the nano-memory cells are amphiphilic block polymer micelle arrays.

[0007] In this invention, amphiphilic block polymers are self-assembled in a solvent to form micelles, which are then arrayed on the surface of a conductive substrate to obtain a nano-memory for ultra-high-density data storage. Preferably, a nanobowl-shaped conductive substrate is prepared using a template method, and then the micelles are induced to array on the surface of the conductive substrate to achieve an arrayed arrangement of the micelles, thus obtaining a nano-memory for ultra-high-density data storage. Preferably, the nanobowl-shaped conductive substrate consists of a supporting substrate and a nanobowl-shaped conductive layer on its surface. The nanobowl-shaped conductive layer is an indium oxide / metal bilayer structure with a nanobowl shape; the supporting substrate is indium tin oxide (ITO) glass.

[0008] In this invention, nitrocarbazole monomer, naphthimide monomer, and hydrophilic monomer undergo ring-opening metathesis polymerization in a solvent to obtain an amphiphilic block polymer. Micelles are then formed through self-assembly in the solvent, and a nano-bowl-shaped conductive substrate is prepared using a template method. The micelles are then arranged in an array through substrate induction, thus realizing the fabrication of a nano-memory. The amphiphilic block polymer is an amphiphilic triblock polymer composed of nitrocarbazole segments, naphthimide segments, and hydrophilic segments. The hydrophilic monomer is a polyethylene glycol monomer, which is polymerized to obtain polyethylene glycol hydrophilic segments. The chemical structural formula of the amphiphilic block polymer is as follows:

[0009]

[0010] Wherein, m is 10-15, n is 5-10, a is 7-12, and b is 10-20; preferably, m is 11-14, n is 6-9, a is 7-10, and b is 10-15.

[0011] This invention designs and synthesizes a novel triblock copolymer, in which nitrocarbazole, naphthalimide, and polyethylene glycol serve as the main functional groups for the hydrophobic and hydrophilic segments, respectively. First, nitrocarbazole monomer is polymerized to obtain nitrocarbazole segments. Then, naphthalimide monomer is added and polymerized to obtain a nitrocarbazole-naphthalimide segment polymer. Finally, polyethylene glycol monomer is added and polymerized to obtain an amphiphilic triblock polymer, i.e., an amphiphilic block polymer composed of nitrocarbazole segments, naphthalimide segments, and polyethylene glycol segments. Preferably, during polymerization, the catalyst is a Grubbs third-generation catalyst, the solvent is dichloromethane, the temperature is 20–40°C, and the environment is an inert gas atmosphere; the polymerization time for each step is 0.5–5 h, preferably 0.5–2 h.

[0012] This invention utilizes nitrocarbazole, naphthalimide, and polyethylene glycol monomers to obtain an amphiphilic block polymer in a solvent. The prepared amphiphilic block polymer is then self-assembled in a solvent containing tetrahydrofuran and water to prepare a micelle solution.

[0013] This invention utilizes an air-water interface self-assembly method to prepare monolayer PS microspheres. Nanobowl arrays are fabricated using PS microspheres as templates, and the array arrangement of micelles is achieved through substrate induction. The performance of the nano-storage device is measured using conductive atomic force microscopy (C-AFM). Specifically, a polystyrene (PS) microsphere dispersion is lifted using indium tin oxide (ITO) glass, followed by lifting with indium nitrate solution, calcination, and metal sputtering to obtain a nanobowl-shaped conductive substrate. The micelle solution is then dropped onto the nanobowl-shaped conductive substrate and dried to obtain a nano-storage device for ultra-high-density data storage. The polystyrene microsphere dispersion consists of polystyrene microspheres, a surfactant, an organic solvent, and water. The organic solvent is a low-boiling-point alcohol. The calcination temperature is 500–700 °C, the time is 1–3 h, and the heating rate is 1–3 °C / min.

[0014] In the above scheme, a solution of PS microspheres is dispersed on the surface of a sodium dodecyl sulfate (SDS) solution, and a monolayer of PS microspheres is pulled using indium tin oxide (ITO) glass. The PS microsphere solution consists of water and ethanol, and the SDS solution concentration is 0.1 mmol / L. The ITO glass slide has dimensions of 1 cm × 2 cm. Then, an indium nitrate solution is used as a precursor to fill the voids in the monolayer PS microspheres. Specifically, the monolayer PS microspheres are transferred to the surface of the indium nitrate solution, pulled out, and calcined at high temperature to obtain an indium oxide nanobowl array. A micelle solution is then dropped into the substrate, and the array arrangement is achieved under the induction of the substrate. Preferably, the indium nitrate solution concentration is 0.2 M. The substrate calcination temperature is 600 °C, the calcination time is 2 h, and the heating rate is 2 °C / min. The micelle solution concentration is 0.0625 mg / mL, and the monodisperse particle size of the PS microspheres is 50–300 nm.

[0015] The advantages of this invention are: the micelles formed by the self-assembly of the amphiphilic block polymer are uniform in size, and the resulting micelles can be regularly arrayed under the induction of the substrate. Simultaneously, the micelles in the substrate possess excellent semiconductor properties and can be used as nanoscale storage cells in the development of storage devices. Compared with traditional storage devices, this innovative method significantly reduces the size of the storage cells and opens up new avenues for the future development of ultra-high-density data storage. Attached Figure Description

[0016] Figure 1 This is a diagram showing the synthesis of amphiphilic block copolymers.

[0017] Figure 2 This is the 1H NMR spectrum of the amphiphilic block copolymer.

[0018] Figure 3 This is a scanning electron microscope image of the micelles.

[0019] Figure 4 This is a scanning electron microscope image of a single-layer polystyrene microsphere template array.

[0020] Figure 5 This is a scanning electron microscope image of the indium oxide conductive substrate.

[0021] Figure 6 This is a scanning electron microscope image of the nano-storage device.

[0022] Figure 7 This is a current-voltage curve of micelles in a nano-storage device.

[0023] Figure 8 It is a carbazole monomer that does not contain nitro groups.

[0024] Figure 9 It is a long-chain polyethylene glycol monomer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to help readers better understand this application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the claims of this application can be achieved. The technical solutions of this invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise stated, the reagents, materials, instruments, etc. used in the following embodiments are all commercially available, and the G3 catalyst is from Ron Reagents. The specific preparation operations and experimental methods are all conventional methods in the art. The NMR test conditions are as follows: the proton NMR spectrum was measured using an INOVA 400MHz FT-NMR spectrometer at a temperature of 25°C. All chemical shifts are given in ppm based on the chemical shift values ​​of tetramethylsilicon (TMS) protons.

[0026] In this invention, when preparing a micelle solution by self-assembling the prepared amphiphilic block polymer in a solvent, the amphiphilic block polymer is dissolved in tetrahydrofuran (THF), and water is added dropwise under conventional stirring. After dialysis, a micelle solution is finally formed. Preferably, the water is added in increments of 10 × 100 μL, 10 × 200 μL, 10 × 400 μL, and 10 × 800 μL, with a dropwise interval of 30 s. The dialysis bag has a molecular weight of 300 K, and the dialysis time is 24 h.

[0027] In this invention, the nanomicelle storage device is fixed on the sample stage of a C-AFM. A voltage is applied to each nanomicelle storage cell within the nanobowl, thereby recording the current-voltage (IV) curve of each storage cell. The testing environment is in air. The measurement mode is contact mode. The conductive probe is a platinum / iridium coated silicon probe.

[0028] Example 1: Synthesis of Amphiphilic Block Copolymers

[0029] Synthesis diagram of amphiphilic block copolymers is shown below Figure 1 As shown, the synthesis of naphthalimide monomer, polyethylene glycol monomer, and nitrocarbazole monomer is an existing technology. For example, the carbazole in the existing synthesis method can be replaced with 3-nitrocarbazole, and the nitrocarbazole monomer can be obtained by reacting step by step. For example, the PEG monomethyl ether in the existing synthesis method can be replaced with 12 repeating units instead of 44, and the polyethylene glycol monomer can be obtained by reacting step by step. Add G3 catalyst (20.075 mg, 0.0275 mmol) to a 20 mL vial, dissolve in 2 mL of dichloromethane, and purge with nitrogen for 2 minutes to remove air. Then add 2 mL of dichloromethane containing nitrocarbazole monomer (169.8 mg, 0.33 mmol), and stir at 28 °C under a nitrogen atmosphere for 1 h to polymerize. Next, add 2 mL of dichloromethane containing naphthimide monomer (137.65 mg, 0.275 mmol), and continue the polymerization reaction for 1 h. Then add 2 mL of dichloromethane containing polyethylene glycol monomer (267.07 mg, 0.33 mmol), and continue the polymerization reaction for 1 h. After the reaction is complete, add 1 mL of vinyl ether and stir again for 0.5 h to terminate the polymerization. Pour the final reaction solution into 200 mL of cold dichloromethane, stir, and a gray precipitate will form. Filter to obtain a solid, dissolve the solid in 5 mL of dichloromethane, and pour into 200 mL of cold dichloromethane again. The polymer was dissolved and purified twice more in cold diethyl ether (mL) using the same method to obtain a pure amphiphilic triblock copolymer, which, after drying, was a reddish-black solid (0.3597 g, 62%). The NMR spectrum of this amphiphilic block copolymer is shown below. Figure 2 .

[0030] Example 2: Preparation of micelles

[0031] 1 mg of the amphiphilic block copolymer was dissolved in 1 mL of tetrahydrofuran. Water was added dropwise while stirring, at increments of 10 × 100 μL, 10 × 200 μL, 10 × 400 μL, and 10 × 800 μL, with 30 s intervals, until the addition was complete and the solution concentration was 0.0625 mg / mL. Stirring continued for 0.5 h. The solution was then placed in a dialysis bag with a molecular weight of 300 k and dialyzed in 2 L of deionized water. The water was changed every 8 h, and this process was repeated three times to obtain a micelle solution. The morphology of the micelles is shown in the figure below. Figure 3 .

[0032] Example 3: Preparation of a monolayer polystyrene (PS) microsphere array

[0033] Monolayer PS microspheres were prepared using an air-water interface self-assembly method. 1 mL of monodisperse PS microspheres with a particle size of 150 nm were placed in a 5 mL vial, and 1 mL of anhydrous ethanol was added. The mixture was sonicated to obtain a PS solution. A 0.1 mmol / L sodium dodecyl sulfate (SDS) aqueous solution was poured into a 600 mL glass petri dish and allowed to stand until no air bubbles appeared on the surface. A 10 cm × 2 cm glass slide was inserted obliquely into the liquid surface. A 10 μL microsyringe was used to add the prepared PS solution onto the glass slide. The solution diffused along the glass slide to the surface and uniformly dispersed and self-assembled to form a monolayer film. A 1 cm × 2 cm ITO glass slide was then obliquely lifted from the liquid surface to adhere the monolayer PS microspheres to the glass. The slide was then allowed to dry. The morphology of the monolayer PS microsphere matrix is ​​shown in the figure below. Figure 4 .

[0034] Example 4: Preparation of Nanomicelle Arrays

[0035] Indium nitrate solution was used as a precursor to fill the voids in a monolayer of PS microspheres. 25 mL of 0.2 M indium nitrate aqueous solution was poured into a 20 mL petri dish. After the liquid surface calmed, a layer of PS microsphere film was lifted using a 1 cm × 2 cm ITO glass (method of Example 3), and then inserted obliquely into the indium nitrate solution. After three seconds, the ITO glass was removed and dried at 70°C for 0.5 h on a heating stage. Then, it was placed in a tube furnace and calcined in air at 600°C for 2 h at a heating rate of 2°C / min. The monolayer of PS microspheres was burned off, and the indium nitrate became indium oxide after calcination, successfully preparing an indium oxide matrix void. Figure 5This image shows an array of indium oxide nanobowl-shaped substrates. After successful fabrication of the matrix void substrate, a layer of gold (10 mA, 70 s) was deposited on its surface to ensure conductivity. Then, 0.5 mL of the previously prepared micelle solution (0.0625 mg / mL) was added obliquely to the matrix substrate, and the substrate was dried at room temperature for 1 h. The nanomicelle spheres dispersed into the nanobowls under the induction of the substrate, forming a matrix arrangement, thus obtaining the nanomicelle storage device. The morphology of the nanomicelle array is shown in the image below. Figure 6 .

[0036] Example 5: Electromagnetic storage performance test of nanomicelle array

[0037] The prepared matrix-type nanomicelle storage devices were fixed on the sample stage of a conductive atomic force microscope (C-AFM). The stage was connected to the gold conductive layer under the micelles with conductive adhesive. In the contact mode of the measurement, the electrical properties of the micelles were tested at the nanoscale in an air-exposed environment. The gold-plated nanomatrix void substrate served as the bottom electrode, and the platinum / iridium conductive probe in contact with the micelles served as the top electrode. A voltage was applied to the nanomicelle storage device in each nanobowl through the conductive probe (a platinum / iridium coated silicon probe), thereby recording the current-voltage (IV) curve of each storage device to obtain its storage performance. Figure 7 The IV curves of the nanomicelles in the fabricated nano-memory device are shown. After scanning from 0 to (-5 V), the device transitions from the OFF state to the ON state. Testing of all memory cells shows that the ternary ratio is 71% and the binary ratio is 29%, indicating that the device can be applied to the development of ternary memory devices.

[0038] Comparative Example

[0039] A layer of gold (10 mA, 70 s) was deposited on the conductive surface of an ITO glass with dimensions of 1 cm × 2 cm, and then 0.5 mL of micelle solution was dropped onto it (Example 2). After drying, the device was obtained. Using the test method of Example 5, all memory cells were tested and the ternary ratio was found to be 39%.

[0040] The nitrocarbazole monomer in Example 1 was adjusted to... Figure 8 The carbazole monomer shown was subjected to the same polymerization to obtain an amphiphilic triblock polymer. The polymer was prepared into a micelle solution using the method of Example 2, and the device was prepared using the method of Example 4. All memory cells were tested using the test method of Example 5, and no ternary memory cells were found.

[0041] The polyethylene glycol monomer in Example 1 was adjusted to... Figure 9The polyethylene glycol monomers shown were subjected to the same polymerization to obtain an amphiphilic triblock polymer. The polymer was prepared into a micelle solution using the method of Example 2, and the device was prepared using the method of Example 4. The ternary ratio was 53% when all memory cells were tested using the test method of Example 5.

[0042] In summary, this invention utilizes micelles self-assembled by amphiphilic block copolymers as nano-memory units, and achieves device fabrication of nano-micelles through the induction of an array substrate. The micelles in the resulting nano-memory device exhibit excellent semiconductor properties. Existing technologies, such as those using DAH triblock amphiphilic polymerization and nano-micelle fabrication, primarily utilize binary storage, with almost no ternary storage. This invention not only yields nano-memory units but also achieves a significant advancement in ternary storage, far exceeding binary storage, providing a new method for the fabrication of next-generation ultra-high-density information storage devices.

Claims

1. A nano-memory for ultra-high density data storage, comprising a conductive substrate and nano-memory cells on the substrate, characterized in that, The nano-storage unit is an amphiphilic block polymer micelle array; the amphiphilic block polymer is composed of nitrocarbazole segments, naphthalimide segments and hydrophilic segments; the conductive substrate is a nanobowl-shaped conductive substrate; the nanobowl-shaped conductive substrate is composed of a supporting substrate and a nanobowl-shaped conductive layer on its surface.

2. The nano-memory for ultra-high density data storage according to claim 1, characterized in that, The chemical structural formula of the amphiphilic block polymer is as follows: ； Where m is 10–15, n is 5–10, a is 7–12, and b is 10–20.

3. The method for fabricating the nano-memory for ultra-high density data storage as described in claim 1, characterized in that, Nitrocarbazole monomer, naphthalimide monomer, and hydrophilic monomer were subjected to ring-opening metathesis polymerization in a solvent to obtain an amphiphilic block polymer, which was then self-assembled into micelles in the solvent. A nanobowl-shaped conductive substrate was prepared by template method, and then the micelles were induced by the nanobowl-shaped conductive substrate to achieve arrayed arrangement, resulting in a nano-memory for ultra-high density data storage.

4. The method for fabricating a nano-memory for ultra-high density data storage according to claim 3, characterized in that, A nanobowl-shaped conductive substrate was obtained by lifting a polystyrene microsphere dispersion with conductive glass, then lifting an indium nitrate solution, followed by calcination and metal sputtering. The micelle solution is then dropped onto a nanobowl-shaped conductive substrate and dried to obtain a nano-memory for ultra-high density data storage.

5. The method for fabricating a nano-memory for ultra-high density data storage according to claim 4, characterized in that, The polystyrene microsphere dispersion is composed of polystyrene microspheres, surfactants, organic solvents and water; the calcination temperature is 500-700℃, the time is 1-3h, and the heating rate is 1-3℃ / min.

6. The application of the nano-memory for ultra-high density data storage as described in claim 1 in the fabrication of organic storage devices.

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