Flexible Optically Controlled Memristor and Preparation Method

Abstract

The present invention relates to a flexible light-controlled memristor, which sequentially includes: a flexible substrate, a bottom electrode, a resistive switching layer, and a top electrode. It is characterized in that the resistive switching layer includes an ABX3 perovskite layer and a metal nanoparticle layer, where A is CH3NH3, B is at least one of Pb, Sn, and Ge, and X is at least one of Cl, Br, and I. The resistive switching active material of the memristor of the present invention is an organic-inorganic hybrid perovskite-metal nanoparticle composite material. By introducing metal nanoparticles to form a protective layer for the perovskite, the environmental stability and thermodynamic stability of the memristor can be improved, it can be operated at a lower voltage so as to reduce the power consumption of the memristor, a new mechanism is introduced to fill the problems in the mechanism of the perovskite-based light-controlled memristor, and large-scale integration can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of flexible electronic devices, and particularly relates to a flexible light-controlled memristor based on a new mechanism of gold nanoparticles-perovskite and a preparation method thereof. Background Art

[0002] As the most basic storage unit in a chip, a memristor is a non-linear resistive device with memory function. Its resistance value can be changed by controlling the change of current, and it is also the most important component in a chip. The core technology of current chips is still to improve China's independent innovation ability of chips and overcome the bottleneck of chip computing power. Scientific researchers have carried out extensive research work from aspects such as new materials, new structures, and new processing technologies, endowing memristors with new properties and uses. Among them, light-controlled memristors are also an important field.

[0003] Perovskite is highly favored for its advantages of broadband visible light absorption, long exciton free path, and low recombination rate, and is an ideal material for light-controlled memristors. However, light-controlled devices based on perovskite have the disadvantages of poor environmental stability and poor thermal stability, which limit their applications in light-controlled devices and neural computing. To solve the above disadvantages and further improve the performance (integration degree, storage capacity), scientific researchers introduce other materials to passivate perovskite.

[0004] For example, in Reference 1, the surface of the CH3NH3PbI3 thin film as a resistive switching layer is passivated by coating oleic acid on the CH3NH3PbI3 thin film to block the contact between the CH3NH3PbI3 thin film and water and oxygen in the air, thereby improving the stability.

[0005] Cited References

[0006] Reference 1: CN107732008A Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in order to overcome the disadvantages of poor environmental stability and poor thermal stability of light-controlled devices based on perovskite, introducing other materials to passivate perovskite often leads to a decrease in optoelectronic performance. Moreover, traditional memristors with electronic conductivity generally have higher electrical initialization voltage and operating voltage. Therefore, it is necessary to reduce their operating voltage and energy consumption. Breaking through this bottleneck awaits the emergence of a new principle of information storage mechanism and device preparation technology in the field of memristors.

[0009] Solutions for Solving the Problems

[0010] In the present invention, a special structure based on surface-functionalized nanoparticles is assembled into a memristive device, and information storage is carried out by using the state changes such as charge distribution, molecular polarization, and interface state changes thereof; the special resistive switching mechanism of this system is utilized to enhance the computing power of the chip; and the multiple resistive switching mechanisms of multi-field and multi-phase effects such as electric field gradient, chemical concentration gradient, and interface diffusion are deeply studied. On this basis, the inventor designed a high-density integrated structure, and developed an array under a new principle of electron-ion collaborative regulation of conductance in the key integration process, realizing large-scale integration.

[0011] Specifically, by using the technical solution described below, the above technical problems can be solved.

[0012] 1. The present invention provides a flexible light-controlled memristor, which sequentially includes: a flexible substrate, a bottom electrode, a resistive switching layer, and a top electrode, characterized in that

[0013] the resistive switching layer includes an ABX3 perovskite layer and a metal nanoparticle layer, where A is CH3NH3, B is at least one of Pb, Sn, and Ge, and X is at least one of Cl, Br, and I.

[0014] 2. The flexible light-controlled memristor according to the above 1, wherein the metal in the metal nanoparticles is at least one of Au, Ag, and Pt.

[0015] 3. The flexible light-controlled memristor according to the above 1 or 2, wherein there is a ligand on the metal nanoparticles, and the ligand is one or more of bis(p-sulfonatophenyl)-phenylphosphine (BSPP), mercaptoundecanoic acid, and N,N,N-(trimethyl)decyl mercaptoundecanoic acid-ammonium chloride.

[0016] 4. A preparation method of the flexible light-controlled memristor according to the above 1, which includes the following steps:

[0017] Provide a flexible substrate;

[0018] Form a bottom electrode on the flexible substrate;

[0019] Form an ABX3 perovskite layer on the bottom electrode;

[0020] Assemble metal nanoparticles on the ABX3 perovskite layer;

[0021] Form a top electrode on the metal nanoparticles.

[0022] 5. The preparation method according to item 4 above, wherein before assembling the metal nanoparticles, the ABX3 perovskite layer is subjected to plasma treatment or laser treatment to introduce free radicals onto the perovskite.

[0023] 6. The preparation method according to item 5 above, wherein after introducing free radicals onto the perovskite, the ABX3 perovskite layer is immersed in a precursor solution of metal nanoparticles, so that the metal precursor is reduced to elemental metal by means of the free radicals.

[0024] 7. The preparation method according to item 6 above, wherein the precursor of the metal nanoparticles is a salt of a metal, a metal chloric acid, a salt of a metal chloric acid, or an acetylacetonate of a metal.

[0025] 8. The preparation method according to item 5 or 6 above, wherein after reducing the metal precursor to elemental metal, ligands are modified on the metal nanoparticles by a ligand exchange method.

[0026] 9. The present invention further provides a memristor array, which comprises the flexible light-controlled memristor according to any one of items 1-3 above.

[0027] 10. The present invention further provides a memory, which comprises the flexible light-controlled memristor according to any one of items 1-3 above or the memristor array according to item 9 above.

[0028] Effects of the Invention

[0029] The resistive switching active material of the present invention is a perovskite-metal nanoparticle composite material. By introducing metal nanoparticles to form a protective layer for the perovskite, the problems of environmental stability and thermodynamic stability of the perovskite-based memristor are solved;

[0030] For the perovskite-metal nanoparticle composite material of the present invention, it is ionically conductive under an electric field. By introducing ligands onto the metal nanoparticles, ions on the ligands are ionized under the electric field to form a gradient electric field, and the gradient electric field and the ions on the perovskite act synergistically to enhance the charge storage capacity;

[0031] Since ionic conduction has a large capacitance, it can be operated at a lower voltage, thereby greatly reducing the power consumption of the memristor. That is, by introducing a new mechanism of ionic conduction, the problem in the mechanism of the perovskite-based light-controlled memristor is filled;

[0032] On the memristor platform, new photon and electron functions can be explored by utilizing the unique optoelectronic properties of metal nanoparticles;

[0033] Both two-dimensional perovskites and metal nanoparticles have broken through the limitations of the rigidity of traditional silicon-based electronic devices and are suitable for flexible electronics, providing new ideas and approaches for integrating devices such as memristors into flexible electronics and demonstrating great potential in chips, human-computer interaction, intelligent robots, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings included in and constituting a part of the specification, together with the specification, illustrate exemplary embodiments, features, and aspects of the present disclosure and are used to explain the principles of the present disclosure.

[0035] Figure 1 Schematic diagram of a flexible memristor based on a new mechanism of metal nanoparticles-perovskite.

[0036] Figure 2 Schematic diagram of a flexible light-controlled memristor array based on a new mechanism of gold nanoparticles-perovskite, where the upper figure is a top view and the lower figure is a side view.

[0037] Figure 3 Raman spectrum of the perovskite prepared in Example 1.

[0038] Figure 4 Graph showing the electrical properties of the light-controlled memristor prepared in Example 1.

[0039] Figure 5 Graph showing the electrical performance curves of the light-controlled memristors prepared in Comparative Example 1 without gold nanoparticles (left figure) and Example 1 with gold nanoparticles (right figure) under different lights.

[0040] Figure 6 Graph showing the real-time curves of the light-controlled memristor with a new mechanism of gold nanoparticles-perovskite prepared in Example 1 under different lights. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The following describes the embodiments of the present invention, but the present invention is not limited thereto. The present invention is not limited to the various configurations described below, and various changes can be made within the scope claimed in the invention. Embodiments and examples obtained by appropriately combining the technical means disclosed in different embodiments and examples are also included in the technical scope of the present invention. In addition, all the documents cited in this specification are incorporated herein by reference.

[0042] Unless otherwise defined, the technical and scientific terms used in the present invention have the same meanings as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0043] In this specification, the numerical range represented by "numerical value A to numerical value B" or "numerical value A - numerical value B" means a range including the endpoint numerical values A and B.

[0044] In this specification, the meaning expressed by "may" includes the meanings of both performing a certain process and not performing a certain process.

[0045] The term "optional" or "optionally" means that the subsequent described event or situation may or may not occur, and this description includes the occurrence and non-occurrence of the described event or situation.

[0046] Throughout this specification, the mention of "an embodiment" or "embodiments" or "in another embodiment" or "in certain embodiments" or "in some embodiments of the present application" means that in at least one embodiment, it includes specific reference elements, structures or features related to those described in that embodiment. Therefore, the phrases "in an embodiment" or "in embodiments" or "in another embodiment" or "in certain embodiments" or "in some embodiments of the present application" that appear at different positions throughout the specification do not necessarily all refer to the same embodiment. In addition, the specific elements, structures or features can be combined in one or more embodiments in any suitable manner.

[0047] The terms "comprising" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method or system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0048] <First aspect>

[0049] The first aspect of the present invention provides a flexible optoelectronic memristor, specifically a flexible memristor based on a new mechanism of metal nanoparticles - perovskite.

[0050] In an embodiment of the present invention, the structure of the flexible optoelectronic memristor is as Figure 1 shown, which successively includes: a flexible substrate, a bottom electrode, an ABX3 perovskite layer, a metal nanoparticle layer, and a top electrode, wherein the resistive switching layer is composed of the ABX3 perovskite layer and the metal nanoparticle layer.

[0051] Resistive Switching Principle

[0052] The resistive switching principle of the flexible memristor based on the new mechanism of metal nanoparticles - perovskite of the present invention is described as follows.

[0053] At the beginning, due to the large resistance of the semiconductor organic-inorganic hybrid perovskite, the channel carrier transport is in an unopened state and the current is very small. Under the electric field, the ions on the metal nanoparticle ligands are ionized to form a gradient electric field. The gradient electric field and the ions on the organic-inorganic hybrid perovskite act synergistically to enhance the charge storage capacity.

[0054] When the bottom electrode is grounded and a certain positive voltage is applied to the top electrode, the ions on the metal nanoparticle ligands are ionized, and the ions are arranged directionally to form a gradient electric field, with the direction pointing to the perovskite. The carrier channel of the perovskite is opened to form a current, and it is in a low-resistance state. As the voltage continues to increase, due to the generated Joule heat, which hinders the carrier migration, a saturation state appears (the current no longer increases after increasing to a certain value). When a reverse voltage is applied, the ions on the metal nanoparticle ligands return from the ionized state to the initial non-ionized state (bound state), which causes the reverse drift of the counterions. The driving force for the carrier migration of the perovskite is insufficient, the current decreases, and the resistance increases. This is equivalent to the "erasing" process. Therefore, the device returns to the high-resistance state.

[0055] Flexible Substrate

[0056] In the present invention, there is no particular limitation on the flexible substrate, and flexible substrates commonly used in the art can be used. For example, in the embodiments of the present invention, the flexible substrate may include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), or polyimide (PI). Among them, polyethylene terephthalate (PET) and polyimide (PI) are preferred.

[0057] Bottom Electrode and Top Electrode

[0058] In the present invention, there is no particular limitation on the bottom electrode and the top electrode, and bottom electrodes and top electrodes commonly used in the art can be used. In the embodiments of the present invention, examples of the materials for the bottom electrode and the top electrode may include ITO, FTO, Pt, Pd, Au, Cr, W, Cu, TiN, etc., which can be selected according to actual needs. In some embodiments of the present invention, the bottom electrode and the top electrode are preferably Au electrodes, Ag electrodes, Pt electrodes, or Pd electrodes. Additionally, the bottom electrode and the top electrode may be the same or different.

[0059] In certain embodiments of the present invention, the length of the bottom electrode may be 2 to 6 mm, preferably 3 to 5 mm, and the thickness may be 30 to 120 nm, preferably 50 to 100 nm. The length of the top electrode may be 0.5 to 5 mm, preferably 1 to 3 mm, and the thickness may be 50 to 250 nm, preferably 100 to 200 nm.

[0060] Resistive Switching Layer

[0061] In the present invention, the resistive switching layer is an ABX3 perovskite layer and a metal nanoparticle layer. That is, the resistive switching active material of the present invention is a perovskite-gold nanoparticle composite material.

[0062] In the above ABX3 perovskite, A can be CH3NH3, B can be at least one of Pb, Sn, and Ge, and X can be at least one of Cl, Br, and I. In an embodiment of the present invention, the ABX3 perovskite is preferably CH3NH3PbI3.

[0063] As can be seen from the above, the ABX3 of the present invention is an organic-inorganic hybrid perovskite. The reason for using the organic-inorganic hybrid perovskite in the present invention is that the organic-inorganic hybrid perovskite can enable the orderly combination of organic and inorganic molecules, and can combine the advantages of both organic and inorganic molecules. For example, the crystal structure of the inorganic component and the strong covalent bond or ionic bond can provide better thermal stability, while the organic component not only has good film-forming properties, but also can change the optoelectronic properties through molecular tailoring. Therefore, in the present invention, the organic-inorganic hybrid perovskite is used.

[0064] In the present invention, the thickness of the perovskite layer as the resistive switching layer can be 1 nm to 10 nm, preferably 1 nm to 5 nm, and the length can be 2 to 5 mm, preferably 2 - 4 mm.

[0065] In an embodiment of the present invention, it is important that a metal nanoparticle layer is assembled on the ABX3 perovskite layer. First, the metal nanoparticles form a protective layer for the perovskite, solving the problems of environmental stability and thermodynamic stability of the perovskite-based memristor. Second, the perovskite-gold nanoparticle composite material of the present invention has ionic conductivity under an electric field. Since ionic conductivity has a large capacitance, it can be operated at a lower voltage, thereby greatly reducing the power consumption of the memristor; third, introducing metal nanoparticles on the perovskite layer introduces a new mechanism, filling the problem in the mechanism of the perovskite-based optoelectronic memristor.

[0066] In an embodiment of the present invention, the metal nanoparticles can be nanoparticles of one or more of Au, Ag, and Pt. Among them, from the perspective of optical properties, Au is preferred.

[0067] The diameter of the metal nanoparticles can be 50 to 300 nm, preferably 100 to 200 nm. In an embodiment of the present invention, the diameter of the metal nanoparticles can be adjusted by the concentration of the metal precursor solution. When the concentration of the metal precursor solution is relatively high, the obtained metal nanoparticles may have a larger particle size. On the contrary, when the concentration of the metal precursor solution is relatively low, the particle size of the metal nanoparticles may be smaller.

[0068] In a preferred embodiment of the present invention, the metal nanoparticles may have modifying ligands. In the present invention, the ligand may be one or more of bis(sulfonic acid phenyl)-phenylphosphoric acid, mercaptoundecanoic acid, N,N,N-(trimethyl) decyl mercaptoundecanoic acid-ammonium chloride, etc. Among them, from the perspective of easy coordination with metals and improving their performance during use, bis(sulfonic acid phenyl)-phenylphosphoric acid is preferably used.

[0069] Since the metal nanoclusters have modifying ligands, the metal nanoclusters with ligands not only passivate the perovskite surface, but also introduce a new mechanism for the memristor due to the special properties of the ligands, thereby further improving the performance. Under an electric field, the ions on the ligands ionize and form a gradient electric field. The gradient electric field acts synergistically with the ions on the inorganic-organic hybrid perovskite to enhance the charge storage capacity.

[0070] <Second aspect>

[0071] In the second aspect of the present invention, a method for preparing a flexible light-controlled memristor is provided. It includes the following steps: a step of providing a flexible substrate; a step of forming a bottom electrode on the flexible substrate; a step of forming an ABX3 perovskite layer on the bottom electrode; a step of assembling metal nanoparticles on the ABX3 perovskite layer; and a step of forming a top electrode on the metal nanoparticles.

[0072] Steps for Providing a Flexible Substrate

[0073] The substrate in this aspect is the same as that in the above <First aspect>.

[0074] The substrate mainly serves to support the light-controlled memristor, so as long as it is ensured to be flat and pollution-free. To ensure the cleanliness of the substrate, the substrate can be cleaned before use, for example, it can be cleaned with water.

[0075] Steps for Forming a Bottom Electrode

[0076] There is no particular limitation on the method for forming the bottom electrode, and the methods commonly used in the art can be used, such as magnetron sputtering, thermal evaporation, physical vapor deposition, etc. The materials used for the bottom electrode are the same as those in the above <First aspect>.

[0077] After forming the bottom electrode, the corresponding shape and size can be prepared by photolithography technology according to the designed dimensions.

[0078] In addition, before forming the perovskite layer on the bottom electrode, it can be subjected to ultraviolet ozone treatment according to needs to clean the bottom electrode.

[0079] Steps for Forming an ABX3 Perovskite Layer

[0080] In the present invention, the method for forming the ABX3 perovskite layer is not particularly limited, and conventional methods in the art can be used. For example, the perovskite layer can be formed on the bottom electrode by methods such as spin coating, drop coating, dip coating, etc. of the perovskite solution.

[0081] Regarding the preparation method of perovskite, common methods in the art can be used. For example, the method in the literature "H. Sun, W. Tian, F. Cao, J. Xiong, L. Li, Ultrahigh-Performance Self-Powered Flexible DoubleTwisted Fibrous Broadband Perovskite Photodetector. Adv. Mater., 2018, 30, 1706986" can be used for preparation. Specifically, AX and BX2 can be mixed in a solvent and reacted under heating and stirring, then filtered, and the obtained perovskite solution can be stored in a brown bottle for later use. Alternatively, in some embodiments, the filtrate can also be dried after filtration to obtain perovskite powder.

[0082] Optionally, the solution of AX can be mixed with the solution of BX2, allowed to react, then filtered, and optionally dried.

[0083] The perovskite solution or perovskite powder is dissolved or dispersed in a solvent, and the perovskite layer is formed on the flexible substrate by methods such as spin coating, drop coating, dip coating, etc. The following takes the drop coating method as an example for illustration.

[0084] The perovskite solution or perovskite powder is dissolved or dispersed in a solvent, stirred for 20 to 40 minutes, then dropped onto the flexible substrate, and then dried at a temperature of 80 to 120 °C for 10 to 30 minutes to form the perovskite layer.

[0085] Examples of A, B, and X are the same as those in the above <First Aspect>.

[0086] Regarding the solvent for dissolving AX and BX2 and the solvent for dissolving or dispersing perovskite, examples thereof may include one or more of water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, caprolactone, butyrolactone, etc. In addition, the solvent for dissolving AX and BX2 and the solvent for dissolving or dispersing perovskite may be the same or different.

[0087] Steps for Assembling Metal Nanoparticles

[0088] After forming the perovskite layer on the bottom electrode, the next step is to assemble metal nanoparticles on the perovskite layer.

[0089] According to the report in the literature "H.T. Baytekin, B. Baytekin, S. Huda, Z. Yavuz, B.A. Grzybowski, Mechanochemical Activation and Patterning of an Adhesive Surface toward Nanoparticle Deposition. J. Am. Chem. Soc, 2015, 137, 1726 - 1729", free radicals can reduce metal nanoparticle precursors to elemental metals, that is, metal nanoclusters.

[0090] Therefore, in the present invention, free radicals are first introduced onto the perovskite surface, and then a composite body including a substrate, a bottom electrode, and a perovskite layer with free radicals introduced on the surface is immersed in a precursor solution of metal nanoparticles, so as to reduce the metal precursor to elemental metal by using free radicals.

[0091] Regarding the method of introducing free radicals, in some embodiments of the present invention, a method of performing plasma treatment or laser treatment on the perovskite can be adopted.

[0092] In the present invention, the precursor of metal nanoparticles can be a metal salt, metal chloric acid, a salt of metal chloric acid, or a metal acetylacetonate, etc., and an easily obtainable metal precursor can be selected according to the selected metal. For example, the precursor can be chloroauric acid, chloroplatinic acid, AgNO3, Pt(acac)2, etc.

[0093] The solvent for dissolving the metal precursor can be water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, caprolactone, or butyrolactone, etc. In the present invention, the solvent for dissolving the metal precursor can be the same as or different from the solvents for dissolving AX and BX2 above.

[0094] In the present invention, the concentration of the metal precursor solution can be 1 mg / ml to 10 mg / ml, preferably 1 mg / ml to 5 mg / ml.

[0095] Regarding the immersion time, it can be 1 to 5 days, preferably 2 to 3 days.

[0096] In a preferred embodiment of the present invention, after reducing the metal precursor to elemental metal, in order to stabilize it, ligands can be modified on the metal nanoparticles by a ligand exchange method. Specifically, the above composite body after being reduced to elemental metal is immersed in a ligand solution.

[0097] The solvent for the ligand solution can be water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, caprolactone, or butyrolactone, etc. The solvent for the ligand solution can be the same as or different from the solvent for dissolving the metal precursor.

[0098] In the present invention, the concentration of the ligand solution can be 1 mmol / L to 10 mmol / L, preferably 2 mmol / L to 3 mmol / L. Regarding the impregnation time, it can be 1 h to 5 h, preferably 2 h to 3 h.

[0099] Steps for Forming a Top Electrode

[0100] In the present invention, since perovskite is not solvent-resistant, photolithography cannot be used when forming the top electrode. In the embodiments of the present invention, a mask method is used and formed by methods such as thermal evaporation and physical vapor deposition.

[0101] <The third aspect>

[0102] In the third aspect of the present invention, a memristor array and a memory are provided. The memristor array of this aspect includes the above-mentioned flexible light-controlled memristor. The memory according to this aspect includes the above-mentioned flexible light-controlled memristor or the above-mentioned memristor array.

[0103] Figure 2 A schematic diagram of the memristor array is shown, where the upper figure is a top view and the lower figure is a side view. As Figure 2 shown, the memristor array is formed by arranging a plurality of memristors. Figure 2 In the shown memristor array, the length of one memristor unit is 3 - 5 mm and the width is 2 - 4 mm. The length of the entire memristor array can be 5 to 10 cm, preferably 5 to 8 cm, and the width can be 2 to 6 cm, preferably 3 to 5 cm.

[0104] Examples

[0105] To further illustrate the present invention, the preparation method and performance of the flexible memristor based on the new mechanism of metal nanoparticles - perovskite provided by the present invention will be described in detail below in conjunction with examples, but they cannot be understood as limiting the protection scope of the present invention.

[0106] Example 1

[0107] (1) Preparation of organic-inorganic hybrid perovskite

[0108] The perovskite CH3NH3PbI3 was prepared by the method in the literature (H. Sun, W. Tian, F. Cao, J. Xiong, L. Li, Ultrahigh-Performance Self-Powered Flexible Double Twisted Fibrous Broadband Perovskite Photodetector. Adv. Mater., 2018, 30, 1706986).

[0109] Specifically, 0.173 g of PbI2 and 0.119 g of CH3NH3I were mixed in 1 mL of caprolactone and magnetically stirred at a temperature of 60 °C. After the reaction, the obtained reaction product liquid was filtered through polytetrafluoroethylene (pore size 0.2 μm) to obtain a perovskite solution, which was injected into a brown bottle and stored in a desiccator.

[0110] (2) Preparation of a flexible light-controlled memristor based on the new mechanism of gold nanoparticles-perovskite

[0111] Step a: Forming a Bottom Electrode

[0112] On the flexible substrate PI, the bottom metal electrodes chromium (7 nm) and gold (70 nm) (chromium was sputtered first and then gold) were prepared by magnetron sputtering, and the corresponding shape and size were prepared by photolithography according to the designed dimensions. In this embodiment, the substrate was rectangular, with a length and width of 50 μm and 30 μm, respectively. Thus, a bottom electrode, that is, a gold electrode, was formed on the flexible substrate.

[0113] Before preparing the perovskite on the electrode, the electrode was treated with ultraviolet ozone (irradiated with a 100 W ultraviolet lamp for half an hour, ozone 30 sccm / min) to clean the bottom electrode.

[0114] Step b: Introducing Free Radicals

[0115] Before coating the perovskite solution on the bottom electrode, the above-prepared perovskite solution was added dropwise during magnetic stirring at 400 rpm in 1,2-dichlorobenzene. After stirring for 30 minutes, it was dropped onto the flexible substrate with the bottom electrode in step a.

[0116] It was treated at 110 °C for 15 min. Then, laser treatment was used to introduce free radicals. The power of the laser was controlled at 20 W and the time was 2 s to introduce free radicals on the ligands of the perovskite.

[0117] Step c: Assembling Metal Nanoparticles

[0118] After introducing free radicals on the perovskite, the composite including the flexible substrate, the bottom electrode, and the perovskite layer with introduced free radicals was immersed in butyrolactone of chloroauric acid (the concentration of chloroauric acid was 2 mg / mL, the precursor of gold nanoparticles). After standing for 5 days, on the ligands of the perovskite, the precursor salt of gold was reduced to elemental gold, that is, gold clusters.

[0119] To stabilize it, ligands were further modified on the gold clusters by the ligand exchange method. Specifically, the composite with free radicals introduced on the surface was immersed in a DMF solution of bis(sulfonic acid phenyl)-phenyl phosphoric acid (the concentration of bis(sulfonic acid phenyl)-phenyl phosphoric acid was 2 mmol / L) for 3 hours.

[0120] Step d: Forming a Top Electrode

[0121] Finally, a top electrode is prepared by thermal evaporation (evaporation rate: The evaporation instrument is set with a current of 100 A) using a mask plate made of titanium alloy. In this embodiment, the top electrode is an Ag electrode.

[0122] Comparative Example 1

[0123] A flexible optoelectronic memristor is prepared in the same manner as in Example 1, except that gold nanoparticles are not assembled.

[0124] Hereinafter, a method for testing the performance of the flexible memristor of the present invention based on the new mechanism of metal nanoparticles - perovskite is described.

[0125] Raman Spectroscopy Test

[0126] A Raman spectrum is obtained by scanning with a PerkinElmer 400+RamanMicro300 model at a wavenumber of 500 - 3000.

[0127] Electrical Property Test

[0128] The semiconductor test instrument Agilent B1500A is used to scan the I-V curve.

[0129] Optical Response Test

[0130] With a visible light laser of 532 nm, the semiconductor test instrument Agilent B1500A is used to scan the I-V curve under illumination with different light intensities of 2 Lm / square meter, 4 Lm / square meter, 6 Lm / square meter, and 8 Lm / square meter.

[0131] Performance test results

[0132] (1) Raman spectrum

[0133] Figure 3 The Raman spectrum of the perovskite prepared in Example 1 is shown. This spectrum is Figure 1 consistent with the Raman spectrum of perovskite CH3NH3PbI3 in the literature, thereby proving that the perovskite prepared by the present invention meets the requirements.

[0134] (2) Electrical properties

[0135] The electrical properties of the flexible optoelectronic memristor based on the new mechanism of gold nanoparticles - perovskite prepared in Example 1 are shown in Figure 4 . By Figure 4As can be seen, its switching ratio reaches 104 and the hysteresis is large. It is worth noting that the operating voltage is very low (less than 1V), enabling low-voltage operation and reducing power consumption.

[0136] (3) Photoresponse

[0137] Figure 5 The electrical performance curves of the photoresistive memristor without gold nanoparticles prepared in Comparative Example 1 (left figure) and the photoresistive memristor with gold nanoparticles prepared in Example 1 (right figure) under different lights of 2 Lm / square meter, 4 Lm / square meter, 6 Lm / square meter, and 8 Lm / square meter are shown. In the left figure, as the light intensity increases, the change in current is not significant; while in the right figure, as the light intensity increases, the change in current is relatively large. This shows that the introduction of gold nanoparticles into the photoresistive memristor with the new perovskite mechanism will increase the photoresponse.

[0138] Figure 6 The real-time curves of the photoresistive memristor with gold nanoparticles in Example 1 under different lights of 2 Lm / square meter, 4 Lm / square meter, 6 Lm / square meter, and 8 Lm / square meter are shown. As can be seen from the figure, the photoresistive memristor with the new perovskite mechanism containing gold nanoparticles is more sensitive to the photoresponse and has a higher sensitivity.

[0139] Industrial Applicability

[0140] The present invention obtains a unique structural design method of a photoresistive memristor with a new perovskite mechanism containing gold nanoparticles by introducing free radicals onto traditional perovskite, causing the reduction of metal nanoparticle precursors by free radicals, and optionally modifying ligands on the metal nanoparticles. This method not only solves the problem of poor stability in perovskite-based memristors, but also enhances the photoresponse due to the special optical properties of gold nanoparticles. In addition, due to ion electronics, low-voltage operation can be achieved, reducing power consumption. Therefore, the photoresistive memristor of the present invention can be used to fabricate memristor arrays and memories.

Claims

1. A flexible light-controlled memristor, which sequentially includes: A flexible substrate, a bottom electrode, a resistive switching layer, and a top electrode, characterized in that: The resistive switching layer includes an ABX3 perovskite layer and a metal nanoparticle layer assembled on the ABX3 perovskite layer, wherein A is CH3NH3, B is one or more of Pb, Sn, and Ge, and X is one or more of Cl, Br, and I. The metal nanoparticles have ligands, and the ligands are one or more of bis(phenylsulfonate)-phenylphosphoric acid, mercapto undecanoic acid, and N,N,N-(trimethyl)decylmercapto undecanoic acid-ammonium chloride. The metal nanoparticles are one or more nanoparticles of Au, Ag, and Pt.

2. A method for preparing the flexible light-controlled memristor according to claim 1, comprising the following steps: providing a flexible substrate; forming a bottom electrode on the flexible substrate; forming an ABX3 perovskite layer on the bottom electrode; Assembling metal nanoparticles on the ABX3 perovskite layer; A top electrode is formed on the metal nanoparticles.

3. The preparation method according to claim 2, wherein before assembling the metal nanoparticles, the ABX3 perovskite layer is subjected to plasma treatment or laser treatment to introduce free radicals on the perovskite.

4. The preparation method according to claim 3, wherein after free radicals are introduced into the perovskite, the ABX3 perovskite layer is immersed in a precursor solution of metal nanoparticles, thereby reducing the metal precursor to a metal element with the help of free radicals. 5 . The preparation method according to claim 4 , wherein the precursor of the metal nanoparticles is a metal salt, metal chloric acid, a metal chloric acid salt, or a metal acetoacetate.

6. The preparation method according to claim 3 or 4, wherein after the metal precursor is reduced to a metal element, the ligand is modified on the metal nanoparticles by a ligand exchange method. 7 . A memristor array comprising the flexible light-controlled memristor according to claim 1 . 8 . A memory comprising the flexible light-controlled memristor according to claim 1 or the memristor array according to claim 7 .

Images