Ag + / Sm 3+ Doped perovskite single crystal containing pn junction, memristor and preparation method thereof

Abstract

The application discloses an Ag + / Sm 3+ Doped perovskite single crystal containing PN junction, memristor and preparation method thereof + / Sm 3+ The preparation method of the doped perovskite single crystal containing PN junction comprises the following steps: dissolving MAX, PbX2 and AgX in a solvent, stirring, then heating and crystallizing, and growing Ag + Doped P-type MAPbX3 single crystal; dissolving MAX, PbX2 and SmX3 in a solvent, stirring, then immersing Ag + Doped P-type MAPbX3 single crystal, then heating and crystallizing, so that Ag + Doped P-type MAPbX3 single crystal, then heating and crystallizing, so that Ag 3+ Doped N-type MAPbX3 single crystal, and the Ag + / Sm 3+ Doped perovskite single crystal containing PN junction. The application utilizes a solution method in-situ growth technology to accurately construct a PN junction in a perovskite single crystal, thereby realizing self-regulation effect and a memristor function of a device, and providing a new technical approach for development of a high-performance and high-density memristor device.

Description

Technical Field

[0001] This invention relates to the field of perovskite memristor technology, and more particularly to an Ag... + / Sm 3+ Doped perovskite single crystals containing PN junctions, memristors and their fabrication methods. Background Technology

[0002] In recent years, perovskite materials have attracted much attention in the field of memristors due to their ability to achieve non-volatile switching of resistance by controlling internal ion migration, defect states, or phase transitions. This resistance switching behavior is not only fast and low-power, but also enables multi-level resistance states, providing possibilities for high-density information storage. However, despite significant progress in laboratory research, perovskite memristors still face challenges in terms of stability and reliability.

[0003] Traditional perovskite memristors mostly employ thin-film structures, whose fabrication process is complex and difficult to control precisely. The uniformity, thickness, and crystal quality of the thin film directly affect the device's performance and reliability. Issues such as grain boundaries, defects, and phase transitions in the thin film can lead to unstable resistance switching behavior, short lifetime, and high power consumption. Furthermore, most perovskite memristors require additional rectifier devices (such as diodes) to achieve unidirectional conductivity and address the "creeping path" problem in cross-arrays. This not only increases the complexity and manufacturing cost of the device but also limits its integration density.

[0004] Current research primarily focuses on optimizing memristor performance by controlling the composition, structure, and defects of perovskite thin films. For example, the ion migration and resistance switching behavior of perovskite materials can be modulated by introducing different dopants, altering the film fabrication process, or designing novel device structures. However, these methods still have limitations in improving device stability and reliability. Summary of the Invention

[0005] The main objective of this invention is to provide an Ag with a self-rectifying effect. + / Sm 3+ Doped perovskite single crystals containing PN junctions, memristors and their fabrication methods.

[0006] To achieve the above objectives, the present invention provides an Ag + / Sm 3+ A method for preparing doped perovskite single crystals containing PN junctions includes the following steps:

[0007] (1)Ag + Growth of doped p-type MAPbX3 single crystals

[0008] MAX, PbX2, and AgX were dissolved in a solvent, stirred, and then heated for crystallization to grow Ag. + Doped p-type MAPbX3 single crystal;

[0009] (2)Sm 3+ Growth of doped N-type MAPbX3 single crystals

[0010] MAX, PbX2, and SmX3 were dissolved in a solvent, stirred, and then immersed in Ag. + P-type MAPbX3 single crystals were doped and then subjected to reheat crystallization treatment to obtain Ag + Sm is epitaxially grown on the surface of a doped p-type MAPbX3 single crystal. 3+ The Ag is obtained by doping N-type MAPbX3 single crystal. + / Sm 3+ Doped perovskite single crystals containing PN junctions;

[0011] All X's above represent halogen atoms.

[0012] Further, in step (1), the solvent is DMF, and the molar ratio of MAX, PbX2 and AgX is 1:1:0.1.

[0013] Further, in step (1), the specific process of heating and crystallization is as follows: first, heat at 90°C for 20 minutes, then gradually increase the temperature to 100-120°C within 30-60 minutes to grow a single daughter crystal, and finally crystallize at 90°C for 3-5 hours.

[0014] Furthermore, in step (2), the solvent is DMF, and the molar ratio of MAX, PbX2 and SmX3 is 1:1:0.1.

[0015] Furthermore, in step (2), the specific process of heating and crystallization is as follows: constant temperature crystallization at 90℃ for 3 to 6 hours.

[0016] Furthermore, the growth rate of perovskite single crystals can be adjusted by changing the concentration of the precursor solution.

[0017] Furthermore, the growth rate of perovskite single crystals can be adjusted by changing the growth temperature.

[0018] The present invention also provides an Ag + / Sm 3+ The doped perovskite single crystal containing a PN junction was prepared according to the above preparation method.

[0019] The present invention also provides a perovskite single-crystal memristor containing a PN junction, comprising the above-mentioned Ag + / Sm 3+The doped perovskite single crystal containing a PN junction, and two metal electrodes respectively attached to the P-type MAPbX3 single crystal and the N-type MAPbX3 single crystal of the perovskite single crystal containing the PN junction.

[0020] Furthermore, the materials of the two metal electrodes are independently selected from Au and Ag, respectively.

[0021] Furthermore, the thickness of the metal electrode is 30–100 nm, and the spacing between the two metal electrodes is 10–300 μm.

[0022] The present invention also provides a method for fabricating the above-mentioned perovskite single-crystal memristor containing a PN junction, comprising the following steps: first, grinding both ends of the perovskite single crystal containing the PN junction to Ag. + The doped P-type MAPbX3 single crystal is exposed, and then the metal electrodes are deposited on the P-type MAPbX3 single crystal and the N-type MAPbX3 single crystal containing the PN junction by electron beam deposition.

[0023] Furthermore, the spacing and shape between the two metal electrodes are controlled by using different mask covering methods, and the evaporation rate is...

[0024] The performance of the perovskite single-crystal memristor containing a PN junction, as described in this invention, can be adjusted by different combinations of parameters, such as the type of metal in the metal electrode, the channel width, the doping concentration of different metal elements, and the types of different metals.

[0025] The concept and principle of this invention:

[0026] This invention utilizes a solution-based in-situ growth technique to precisely construct a PN junction within a perovskite single crystal, thereby achieving self-rectification and memristor functionality in the device. Specifically, Ag is introduced through a two-step growth process. + and Sm 3+Metal ions are used to dope perovskite single crystals, forming P-type and N-type regions within the crystal and creating a high-quality PN junction between them. Due to the built-in electric field of the PN junction, the device exhibits a distinct unidirectional conductivity in its electrical performance characterization: when a negative bias is applied, current easily flows through the PN junction, and the device exhibits a low-resistance state (LRS); while when a positive bias is applied, the current is suppressed, and the device maintains a high-resistance state (HRS), thus achieving a self-rectification effect. Furthermore, by applying different voltage pulses, ion migration and defect states within the PN junction region can be effectively controlled, enabling reversible switching of the device's resistance between high and low resistance states, thus endowing the device with memristor functionality. This self-rectifying memristor structure based on in-situ grown PN junctions ensures interface quality and doping uniformity, improving device stability and reliability. It not only simplifies device design and increases integration density but also achieves stable resistance switching and excellent self-rectification characteristics by controlling ion migration and defect states. This invention utilizes the excellent properties of perovskite single crystals and the rectification characteristics of PN junctions to provide a new technical approach for the development of high-performance, high-density memristor devices.

[0027] The beneficial effects of this invention are reflected in:

[0028] This invention employs a solution-based in-situ single-crystal growth technique, which solves problems inherent in traditional thin-film perovskite memristors, such as poor film uniformity, the need for additional rectifier devices, suboptimal stability, and difficulties in controlling ion migration. The core innovation of this invention lies in: utilizing a solution method to grow a PN junction in situ on a MAPbX3 single-crystal substrate, through Ag… + and Sm 3+ Metal ion doping enables the construction of high-quality PN junctions within a single crystal. This structure imparts the following significant advantages to the device:

[0029] 1. Simplify device structure and improve integration density: By leveraging the built-in electric field of the PN junction, a self-rectification effect is achieved, eliminating the need for additional rectifier diodes. This solves the creeping path problem in cross arrays, significantly simplifying device structure, increasing integration density, and reducing manufacturing costs.

[0030] 2. Improve device stability and reliability: The use of a single-crystal substrate and in-situ grown PN junctions effectively reduces interface defects and grain boundaries, improves interface quality and charge transport efficiency, thereby significantly enhancing the stability and reliability of the device.

[0031] 3. Precise control of electrical performance: By controlling the type and concentration of doped ions, the electrical properties of perovskite materials can be precisely controlled, the resistance switching behavior of the device can be optimized, and the memristor characteristics of low power consumption and high sensitivity can be achieved.

[0032] 4. Simple and controllable preparation process: The solution method for in-situ growth of PN junctions is relatively simple and easy to control, achieving uniform distribution of doped ions and ensuring high-quality formation of PN junctions. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the fabrication process of a memristor according to an embodiment of the present invention.

[0034] Figure 2 This is a graph showing the current-voltage test results of a memristor according to an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0036] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0037] Example 1

[0038] Ag + / Sm 3+ Fabrication of doped perovskite single crystals containing PN junctions and memristors

[0039] For the preparation process, please refer to [link / reference]. Figure 1 .

[0040] (1) Preparation of the device

[0041] Prepare 10ml glass bottles, use a nitrogen gun to clean the inside of the glass bottles, use an ultrasonic cleaner to clean the magnetic ferrule, then use a nitrogen gun to dry the adhering deionized water and dry it in a vacuum drying oven; prepare two sets of the above.

[0042] (2)Ag + Growth of doped p-type MAPbBr3 single crystals

[0043] Mix 0.1 mmol of methylammonium bromide (MABr), 0.1 mmol of lead bromide (PbBr2), 0.01 mmol of silver bromide (AgBr) with 1 ml of dimethylformamide (DMF) and stir for 1 h. Filter the mixture using a filter plug with a pore size of 0.22 μm and then place it into a glass bottle.

[0044] The glass bottle was placed on a 90°C heating stage and heated for 20 minutes. Then, the temperature was gradually increased at a rate of 1°C / min (generally, a single daughter crystal appears between 100 and 120°C) until a single daughter crystal appeared in the solution. The glass bottle was then transferred to a 90°C heating stage and kept at that temperature for 4 hours. Ag crystals with a side length of approximately 3–5 mm grew in the glass bottle. + The doped P-type MAPbBr3 single crystal was removed with tweezers and quickly transferred to absorbent paper to remove excess solution from the surface.

[0045] (3)Sm 3+ Growth of doped N-type MAPbBr3 single crystals

[0046] 0.1 mmol of methylammonium bromide (MABr), 0.1 mmol of lead bromide (PbBr2), 0.01 mmol of samarium bromide (SmBr3) and 1 ml of dimethylformamide (DMF) were mixed and stirred for 1 h. After filtration through a filter plug with a pore size of 0.22 μm, the mixture was placed in a glass bottle and then immersed in the Ag obtained in step (1). + Doped p-type MAPbBr3 single crystal;

[0047] The glass bottle was placed on a heating plate at 90℃ and kept at a constant temperature for 5 hours to allow Ag to grow. + Sm is epitaxially grown on the surface of a doped p-type MAPbBr3 single crystal. 3+ Doped N-type MAPbBr3 single crystals, the combination of the two, constitute the Ag required for device fabrication. + / Sm 3+ The doped perovskite single crystal containing a PN junction has a side length of about 6-10 mm. Use tweezers to take out the single crystal and quickly transfer it to absorbent paper to remove excess solution from the surface.

[0048] (4) Evaporation of metal electrodes

[0049] Using fine sandpaper, grind away 2.2–3.0 mm from both ends of the perovskite single crystal containing the PN junction obtained in step (3), leaving only the middle part with a thickness of approximately 2–3 mm. At this point, the surfaces of the two ends of the middle part are: the middle part is Ag. + A doped p-type MAPbBr3 single crystal with an outer Sm... 3+ The surface of the middle part of the doped N-type MAPbBr3 single crystal was rinsed with DMF solvent and dried on a heating stage at 60°C for 30 min.

[0050] Using electron beam coating, The rate is at 10 -6 Electrode deposition under vacuum conditions, Sm on one end face of the middle portion. 3+ Silver electrode 1, Ag was deposited on a doped N-type MAPbBr3 single crystal.+ Gold electrode 2 is deposited on a doped P-type MAPbBr3 single crystal. The thickness of silver electrode 1 and gold electrode 2 is controlled between 30 and 100 nm. The spacing between the two metal electrodes is determined by using different custom mask covering methods. The spacing between silver electrode 1 and gold electrode 2 is controlled between 10 and 300 μm, resulting in a perovskite single crystal memristor containing a PN junction.

[0051] Experimental Example 1

[0052] Performance testing of perovskite single-crystal memristors containing PN junctions

[0053] The memristor selected for testing was a perovskite single crystal with a PN junction, with an overall size of 8*8mm and Ag... + The doped P-type MAPbBr3 single crystal has a size of 4*4mm. After polishing, the middle part is 2.5mm thick. The silver electrode 1 and gold electrode 2 have a size of 1μm*1μm and a thickness of 30nm. The distance between the silver electrode 1 and gold electrode 2 is 100μm.

[0054] The electrical characteristics of the memristor were characterized using a Keysight B1500A semiconductor parameter analyzer, measured on a probe stage and inverted microscope. Voltage measurements were taken using a sweepback method. Test results are available in [reference needed]. Figure 2 Perovskite single-crystal memristors containing PN junctions exhibit a sudden change from a high-resistivity state (HRS) to a low-resistivity state (LRS) during negative voltage retracement, while maintaining a high-resistivity state (HRS) during positive voltage retracement, demonstrating a self-rectification effect.

[0055] The photosynaptic characteristics of the memristor were characterized using a Keysight B1500A semiconductor parameter analyzer, measured on a probe stage and inverted microscope, to determine the resistive switching performance of the device. Test results are available in [reference needed]. Figure 2 .

[0056] Figure 2 This diagram details the self-rectification characteristics and resistance switching behavior of memristors. It presents a current-voltage (IV) characteristic curve of a memristor, revealing its unique operating principle. The horizontal axis represents voltage (V), ranging from -3V to +3V, and the vertical axis represents current (A), expressed logarithmically, ranging from 1E-11A to 0.1A. Two distinct curves represent different voltage sweep directions, revealing the device's resistive switching behavior and self-rectification characteristics.

[0057] First, when the voltage is scanned negatively from 0V to -3V, the device is initially in a high-resistivity state (HRS), and the current remains at a low level (approximately 1E-7A). As the negative voltage increases, the current rises slowly until it reaches a threshold voltage (approximately -1V), at which point the device suddenly undergoes a resistance change, transitioning from the high-resistivity state to the low-resistivity state (LRS), and the current rapidly increases to over 0.01A. During the negative voltage sweepback to 0V, the device remains in the low-resistivity state, and the current gradually decreases.

[0058] Then, as the voltage is scanned forward from 0V to +3V, the device remains in a high-resistivity state, and the current remains at a low level (between 1E-7A and 1E-6A), with almost no noticeable resistance change. During the forward voltage rewind to 0V, the device also remains in a high-resistivity state.

[0059] This asymmetric IV characteristic indicates that the memristor device exhibits a significant self-rectification effect, meaning it readily undergoes resistive switching under negative voltage but struggles to do so under positive voltage. This characteristic may stem from mechanisms such as the internal PN junction structure or Schottky barrier.

[0060] Furthermore, the figure also shows the resistance switching behavior of the device between high and low resistance states. During the negative voltage scan, the device's resistance switches from a high resistance state (approximately 10^7 ohms) to a low resistance state (approximately 10^2 ohms), a resistance change of approximately 10^5 times, i.e., a current switching ratio of ~10. 5 This large current switching ratio is crucial for memristor non-volatile storage and neuromorphic computing applications.

[0061] The use of MAPbBr3 perovskite single crystal as an example in this invention is for illustrative purposes only and is not intended to limit the invention. Utilizing other halide perovskite materials as the parent material for PN junctions, such as CsPbI3, CsPbCl3, MAPbBr3, and MAPbI3, and employing solution methods to achieve P-type and N-type doping control to form high-quality in-situ grown PN junction perovskite single crystals, should also fall within the scope of protection of the appended claims.

[0062] The Au / Ag asymmetric electrode is used to explain the invention only and is not intended to limit the invention. Self-rectifying memristors prepared using other electrode combinations, such as Cr / Cu, Cr / Ni, symmetric electrodes such as Au / Au, and asymmetric electrodes such as Cr / Cu-Cr / Au, Cr / Ag-Cr / Au, Cr / Ni-Cr / Au, etc., should also fall within the protection scope of the appended claims.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An Ag + / Sm 3+ A method for preparing doped perovskite single crystals containing PN junctions, characterized in that, Includes the following steps: (1) Ag + Growth of doped p-type MAPbX3 single crystals MAX, PbX2, and AgX were dissolved in a solvent, stirred, and then heated for crystallization to grow Ag. + Doped p-type MAPbX3 single crystal; In step (1), the solvent is DMF, and the molar ratio of MAX, PbX2 and AgX is 1:1:0.1; In step (1), the specific process of heating and crystallization is as follows: first, heat at 90℃ for 20 min, then gradually increase the temperature to 100-120℃ within 30-60 min to grow a single daughter crystal, and finally crystallize at 90℃ for 3-5 h. (2) Sm 3+ Growth of doped N-type MAPbX3 single crystals MAX, PbX2, and SmX3 were dissolved in a solvent, stirred, and then immersed in Ag. + P-type MAPbX3 single crystals were doped and then subjected to reheat crystallization treatment to obtain Ag + Sm is epitaxially grown on the surface of a doped p-type MAPbX3 single crystal. 3+ The Ag is obtained by doping N-type MAPbX3 single crystal. + / Sm 3+ Doped perovskite single crystals containing PN junctions; In step (2), the solvent is DMF, and the molar ratio of MAX, PbX2 and SmX3 is 1:1:0.1; In step (2), the specific process of heating and crystallization is as follows: constant temperature crystallization at 90℃ for 3 to 6 hours; All X's above represent halogen atoms.

2. An Ag + / Sm 3+ A doped perovskite single crystal containing a PN junction, characterized in that, Prepared according to the preparation method described in claim 1.

3. A perovskite single-crystal memristor containing a PN junction, characterized in that, Including Ag as described in claim 2 + / Sm 3+ The doped perovskite single crystal containing a PN junction, and two metal electrodes respectively attached to the P-type MAPbX3 single crystal and the N-type MAPbX3 single crystal of the perovskite single crystal containing the PN junction.

4. The perovskite single-crystal memristor containing a PN junction as described in claim 3, characterized in that, The materials of the two metal electrodes are independently selected from Au and Ag, respectively.

5. The perovskite single-crystal memristor containing a PN junction as described in claim 3 or 4, characterized in that, The thickness of the metal electrode is 30–100 nm, and the spacing between two metal electrodes is 10–300 μm.

6. The method for fabricating a perovskite single-crystal memristor containing a PN junction as described in claim 3, 4, or 5, characterized in that, Includes the following steps: First, grind both ends of the perovskite single crystal containing the PN junction to Ag. + The doped P-type MAPbX3 single crystal is exposed, and then the metal electrodes are deposited on the P-type MAPbX3 single crystal and the N-type MAPbX3 single crystal containing the PN junction by electron beam deposition.

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