Preparation method and application of non-woven fabric film piezoelectric device of metal halide fiber crystal

Abstract

The invention discloses a preparation method and application of a non-woven fabric film piezoelectric device of metal halide fiber crystals, and belongs to the technical field of flexible functional devices. Organic amine ligands and inorganic ligands are used as raw materials, and a solution is promoted to be supersaturated and the metal halide fiber crystals are separated out through a solvent diffusion method, a solvent volatilization method or a cooling crystallization method; metal halide fiber crystals are prepared into a non-woven fabric fiber membrane through suction filtration, and the fiber crystals have the structural characteristic of mutually crossed textures; electrodes and wires are arranged outside the two sides of the non-woven fabric fiber membrane, and the non-woven fabric membrane piezoelectric device is manufactured through silica gel packaging. The device makes full use of the stress sensitivity and intrinsic piezoelectricity of the fiber crystal, is applied to the field of flexible piezoelectric devices, and studies the human body sensing response capability and underwater ultrasonic detection capability of the device. In the preparation process, a high-temperature and high-pressure technological process is not needed, the requirement for experimental equipment is low, and the preparation method is easy to operate and low in cost.

Description

(1) Technical field:

[0001] The present invention belongs to the technical field of flexible functional devices and relates to a preparation method and application of a non-woven fabric film piezoelectric device of metal halide fiber crystals. (2) Background technology:

[0002] The piezoelectric effect refers to the generation of electric charge or voltage on the surface of a piezoelectric material when it is subjected to an external stress, which is also called the direct piezoelectric effect. Conversely, when an electric field is applied to a piezoelectric material, the piezoelectric material will deform and mechanically strain, which is called the inverse piezoelectric effect. The piezoelectric effect has demonstrated its unique value in many fields such as sensing technology, energy collection and conversion, and medical equipment. Although traditional piezoelectric crystal materials are highly favored due to their high piezoelectric coefficient and low economic cost, their high hardness, difficulty in processing, and limited tensile properties have become bottlenecks in their daily applications. These characteristics limit their potential for use in a wider range of scenarios.

[0003] As an important piezoelectric material, metal halide has shown broad application potential in many fields due to its high piezoelectric coefficient, low acoustic impedance and tunable structure. The uniqueness of these materials is that they can be adjusted in chemical composition, crystal structure and different dimensions, thus providing a diverse platform for the regulation of optoelectronic properties. However, the high brittleness and low fracture toughness of metal halide single crystals are indeed a challenge that limits their application in flexible electronic devices. This brittleness means that the material is prone to sudden fracture under mechanical stress, which is an obvious limitation for application scenarios that require flexible and stretchable properties (such as wearable devices). Therefore, although metal halides have excellent piezoelectric properties, in practical applications, their brittleness problem needs to be overcome through material engineering and innovative design to achieve effective application in flexible electronic devices. To overcome these limitations, researchers have developed flexible piezoelectric composites to improve the shortcomings of current inorganic piezoelectric materials, so that the new materials have the advantages of both piezoelectric crystals and ceramics, and have good chemical stability, flexibility and high electromechanical coupling coefficient. However, due to the limitations of polymers, their piezoelectric properties cannot be fully utilized, and the inevitable interface compatibility issues between the two materials often have a significant impact on their performance.

[0004] Elastic piezoelectric metal halide crystals have high dynamic sensitivity, can respond quickly to mechanical vibrations, and achieve high electromechanical conversion efficiency. In addition, their reversible bending ability changes the characteristics of crystals that are easily broken or irreversibly deformed under stress, greatly improving the ability of crystals to resist external damage. Taking advantage of the flexible characteristics of fiber crystals, they can be prepared into fiber crystal non-woven membranes. This material can not only fully release the inherent piezoelectric properties of piezoelectric crystals, but also effectively circumvent the problem of piezoelectric performance degradation that may be caused by modulus mismatch and interface fusion during the material composite process. In addition, this non-woven membrane has shown great application prospects in the field of underwater ultrasonic detection technology due to its excellent acoustic resolution, significant piezoelectric response and low acoustic impedance characteristics.

[0005] Therefore, exploring how to effectively integrate flexible crystals into flexible devices to fully utilize their crystalline properties and flexibility advantages has become one of the key challenges that need to be urgently addressed in the field of flexible functional materials. (3) Summary of the invention:

[0006] The purpose of the present invention is to provide a preparation method and application of a non-woven membrane piezoelectric device of metal halide fiber crystals, which can solve the above-mentioned problems existing in the prior art. The present invention uses organic amine ligands and inorganic ligands as raw materials to synthesize metal halide crystals with elastic bending ability, and prepares size-controllable non-woven fiber membranes and flexible membrane devices thereof by a simple filtration method; the preparation process does not require a high-temperature and high-pressure process flow, has low requirements for experimental equipment, and is a simple to operate, low-cost preparation method.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal comprises the following steps:

[0009] (1) Using organic amine ligands and inorganic ligands as raw materials, the solution is supersaturated and metal halide fiber crystals are precipitated through solvent diffusion method, solvent volatilization method or cooling crystallization method;

[0010] (2) preparing the metal halide fiber crystals obtained in step (1) into a non-woven fiber membrane by suction filtration, wherein the fiber crystals have a structural feature of cross-texture;

[0011] (3) Electrodes and wires are added to both sides of the non-woven fiber membrane prepared in step (2), and the non-woven membrane piezoelectric device is made by encapsulating it with silica gel.

[0012] The organic amine ligand is a chiral organic amine containing a hydroxyl group, which is (R)-3-amino-1,2-propylene glycol, (S)-3-amino-1,2-propylene glycol, D-cyclohexylglycine, (1R, 2S)-2-phenylcyclopropylamine, (1S, 2R)-aminoindanol or (S)-N-Boc-3-hydroxypyrrolidine.

[0013] The inorganic ligand is a metal salt of lead iodide, lead bromide, cadmium bromide, copper bromide, lead chloride, cadmium chloride or copper chloride.

[0014] The metal halide fiber crystal is a non-centrosymmetric, one-dimensional fiber crystal with a space group of P212121. The diameter of the fiber crystal is in the range of 1-100 microns and the length is in the range of 1-500 microns.

[0015] The metal halide fiber crystal has elastic bending ability, and can realize bending deformation of the crystal without destroying the crystal structure under external stress conditions. After the external force is removed, the crystal returns to its original state.

[0016] The metal halide fiber crystal has low mechanical anisotropy, low acoustic impedance, and high shear piezoelectric properties. For example, the Young's modulus, shear modulus, and linear compressibility anisotropy of (R)-3-amino-1,2-propylene glycol iodide hydrate are 1.62, 1.61, and 1.72, respectively; its maximum longitudinal wave acoustic impedance is 10.75 Mrayls, and its minimum longitudinal wave acoustic impedance is 8.99 Mrayls; its shear piezoelectric coefficients are d 14 =-25.02, d 25 =-11.29, d 36 =-11.96.

[0017] The non-woven fiber membrane is made by filtration through a filter membrane. Depending on the selected metal halide, its appearance color is light yellow or white. The non-woven fiber membrane is connected by cross-weaving between fiber crystals. The membrane diameter is 4.0, 7.5, and 9.5 cm. The size of the non-woven fiber membrane can be adjusted according to the size of the selected filter membrane to produce non-woven fiber membranes of different sizes and thicknesses.

[0018] The non-woven fiber membrane is flexible and can be bent by applying appropriate external force. After the external force is removed, it returns to its original state without causing destructive damage.

[0019] The non-woven membrane piezoelectric device is mainly composed of a non-woven fiber membrane with piezoelectric effect, electrodes are sprayed or pasted on both sides of the membrane, and wires are connected to the electrodes to form a sandwich-type device, and the packaging material is used as the packaging layer.

[0020] The electrodes include materials with excellent electrical conductivity such as silver, copper, platinum, and graphite; the wires include materials with excellent electrical conductivity such as silver, copper, and platinum; and the encapsulation materials include polymer materials such as silicone, polydimethylsiloxane, and polylactic acid.

[0021] The non-woven fabric membrane piezoelectric device has piezoelectricity, is sensitive to external stress stimulation, can generate electrical signals in response to changes in human body movements, can be used in the sensing field, and can be used as a sensor to detect human body movements.

[0022] The non-woven membrane piezoelectric device has piezoelectricity, is sensitive to external sound wave stimulation, can generate electrical signals in response to underwater sound wave stimulation, can be used in the field of sound wave detection, and can generate sound wave signals in response to underwater sound wave stimulation.

[0023] The method for preparing the metal halide fiber crystal comprises the following steps:

[0024] (1) dissolving an inorganic ligand in an acidic solvent to obtain solution A;

[0025] (2) adding an organic amine ligand to solution A, adding a reagent that can dissolve the organic amine, and heating or ultrasonicating to obtain a clear solution B;

[0026] (3) adding an antisolvent that can fully volatilize and diffuse in the container, placing the open sample bottle of Solution B into the container containing the antisolvent and sealing it, so that Solution B and the antisolvent diffuse into each other;

[0027] (4) Solvent diffusion exchange or slow cooling to supersaturate the solution to obtain fibrous crystals;

[0028] (5) After removing the solvent from the fibrous crystals, metal halide fibrous crystals are obtained.

[0029] The molar ratio of the metal ion to the organic amine in the inorganic ligand is 1:1;

[0030] In step (1), the acidic solvent is one of hydroiodic acid, hypophosphorous acid, hydrochloric acid, and hydrobromic acid, or a mixed solution thereof;

[0031] The reagent capable of dissolving the organic amine in step (2) is an organic solvent such as acetonitrile, methanol, isopropanol, or water;

[0032] In the step (3), the anti-solvent that can fully volatilize and diffuse in the container is ethyl acetate.

[0033] When the inorganic ligand is lead iodide and the organic amine ligand is (R)-3-amino-1,2-propylene glycol, the method for preparing the chiral metal halide fiber crystal material is:

[0034] Step 1, dissolving lead iodide in a mixed solution of hydroiodic acid, hypophosphorous acid and acetonitrile to obtain solution A;

[0035] Step 2: adding the organic amine ligand (R)-3-amino-1,2-propanediol to solution A, and ultrasonicating at room temperature to obtain a clear solution B;

[0036] Step 3: Add ethyl acetate to the container, place the open sample bottle of Solution B into the container containing ethyl acetate, and seal it to allow Solution B and the antisolvent to diffuse into each other;

[0037] Step 4: After solvent diffusion exchange, yellow fibrous crystals of (R)-3-amino-1,2-propylene glycol hydrated lead iodide are obtained;

[0038] Step 5: The yellow fibrous crystals of (R)-3-amino-1,2-propanediol lead iodide hydrate are filtered, washed with ethyl acetate, and dried at room temperature to remove the solvent to obtain an aqueous crystalline product: (R)-3-amino-1,2-propanediol lead iodide hydrate.

[0039] The method for preparing the non-woven fiber membrane comprises the following steps:

[0040] Step 1: Weigh metal halide fiber crystals according to the size and thickness of the target film. To ensure that the target film is fully interwoven and maintains a certain degree of flexibility, the crystal film thickness should be in the range of 0.5-3 mm, and the amount of crystals used per square centimeter of film should be in the range of 0.01-0.1 g. The crystals are dispersed in a relatively volatile poor solvent for the crystals to obtain a mixture A.

[0041] Step 2: Ultrasonic dispersion of the mixture A to ensure that the fiber crystals are evenly dispersed in the solution, and the mixture A is filtered using a filter membrane of target diameter to obtain metal halide fiber crystal non-woven fiber membranes B of different diameters and thicknesses.

[0042] The poor solvent with good volatility is ethyl acetate.

[0043] The method for preparing a non-woven fiber membrane into a non-woven membrane piezoelectric device comprises the following steps:

[0044] Step 1: spray or adhere electrodes to the upper and lower surfaces of the non-woven fiber membrane B to obtain an electrode-covered non-woven fiber membrane C;

[0045] Step 2: Glue the wires to the upper and lower electrode layers of the non-woven fiber membrane C to obtain a non-woven fiber membrane D with electrodes and connecting wires;

[0046] Step 3: The potting material is spread all over the fiber crystal membrane and infiltrated into the interior of the non-woven fiber membrane. After the potting material is formed, a non-woven membrane piezoelectric device is obtained.

[0047] The electrodes include materials with excellent electrical conductivity such as silver, copper, platinum, and graphite; the wires include materials with excellent electrical conductivity such as silver, copper, and platinum; and the encapsulation materials include polymer materials such as silicone, polydimethylsiloxane, and polylactic acid.

[0048] The present invention also provides an application of the non-woven fabric film piezoelectric device of the metal halide fiber crystal in the field of flexible piezoelectric devices to study the human body sensing response capability and underwater ultrasonic detection capability of the device.

[0049] The non-woven fabric membrane piezoelectric device has piezoelectricity, is sensitive to external stress stimulation, can generate electrical signals in response to changes in human body movements, can be used in the sensing field, and can be used as a sensor to detect human body movements.

[0050] The non-woven membrane piezoelectric device has piezoelectricity, is sensitive to external sound wave stimulation, can generate electrical signals in response to underwater sound wave stimulation, can be used in the field of sound wave detection, and can generate sound wave signals in response to underwater sound wave stimulation.

[0051] The present invention discloses the following technical effects:

[0052] The present invention utilizes organic amine ligands and inorganic ligands as raw materials to produce flexible fiber piezoelectric crystals with elastic bending properties. This crystal material exhibits low anisotropy, low acoustic impedance, and high shear piezoelectricity. Leveraging the flexible properties of the fiber crystals, a non-woven membrane of the fiber crystals is prepared by filtration. By varying the amount of crystals used and the size of the filter membrane, fiber crystal non-woven membranes of varying sizes and thicknesses can be prepared. A metal halide fiber membrane device is prepared by coating electrodes on the surface of the fiber crystal non-woven membrane, connecting wires, and using a polymer material as an encapsulation layer. This device exhibits piezoelectric properties. When appropriate stress is applied to the device surface, polarization occurs on the fiber crystal surface within the device, leading to charge accumulation. This surface charge is collected by an oscilloscope or other device, generating a specific electrical signal. Similarly, when acoustic waves are applied to the device surface, charge accumulation occurs within the device, generating an electrical signal. The generation of this electrical signal is closely related to the magnitude and frequency of the external stimulus, as well as the environmental conditions in which the device is located. This indicates that the metal halide fiber crystal non-woven fabric membrane piezoelectric device prepared by the present invention has great application potential in the fields of sensing and acoustic wave detection.

[0053] This method utilizes room-temperature preparation, solvent diffusion growth to produce fiber crystals, and further filtration to produce a nonwoven membrane. This method offers advantages such as low energy consumption, low cost, simple operation, and high speed. It fully utilizes the flexibility and piezoelectricity of fiber crystals, providing a new approach for the preparation of flexible piezoelectric devices. (4) Description of the accompanying drawings:

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1-1 This is a physical picture of the non-woven fabric film piezoelectric device of the metal halide fiber crystal according to an embodiment of the present invention. Figure 1-2 This is a schematic structural diagram of a non-woven fabric film piezoelectric device of metal halide fiber crystals according to an embodiment of the present invention;

[0056] Figure 2 A three-dimensional representation of the Young's modulus, acoustic velocity, and piezoelectric coefficient of the metal halide fiber crystal according to an embodiment of the present invention;

[0057] Figure 3-1 The preparation process of the non-woven membrane of metal halide fiber crystals according to the embodiment of the present invention is as follows: Figure 3-2 Actual images of different sizes of non-woven fabric membranes of metal halide fiber crystals according to embodiments of the present invention;

[0058] Figure 4 Surface morphology and element distribution of the non-woven fabric membrane of the metal halide fiber crystal according to an embodiment of the present invention;

[0059] Figure 5 The piezoelectric device of the non-woven fabric film of the metal halide fiber crystal according to the embodiment of the present invention is used as a sensing device to detect the output signal of human activities;

[0060] Figure 6 This is a schematic diagram of a piezoelectric device of a non-woven fabric membrane of a metal halide fiber crystal according to an embodiment of the present invention used as a detection device to detect an output signal of underwater ultrasonic excitation;

[0061] Figure 7 The piezoelectric device of the non-woven fabric membrane of the metal halide fiber crystal according to the embodiment of the present invention is used as a detection device to detect the output signals of underwater ultrasonic excitation of different frequencies;

[0062] Figure 8 The piezoelectric device of the non-woven fabric film of the metal halide fiber crystal according to the embodiment of the present invention is used as a detection device to detect the output signal of ultrasonic excitation in pure water and seawater;

[0063] Figure 9 The piezoelectric device of the non-woven fabric membrane of the metal halide fiber crystal according to the embodiment of the present invention is used as a detection device to detect the output signal of ultrasonic excitation at different distances from the sound source in seawater;

[0064] Figure 10The piezoelectric device of the non-woven fabric membrane of the metal halide fiber crystal according to the embodiment of the present invention is used as a detection device to detect the output signal of ultrasonic excitation at different depths in seawater. (V) Specific implementation methods:

[0065] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0066] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0067] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0068] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0069] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0070] The metal halide fiber crystal nonwoven membrane piezoelectric device of the present invention does not require expensive equipment or complex processes; it can be prepared in an ordinary laboratory using a small amount of raw materials. This simple method retains the crystal's inherent high piezoelectricity while imparting a degree of flexibility to the device. This method fully utilizes the high piezoelectricity, low acoustic impedance, and high mechanical sensitivity of the metal halide fiber crystal, resulting in a highly efficient and low-cost process.

[0071] Example: Preparation of a piezoelectric device based on a non-woven membrane of metal halide fiber crystals: In a 20 mL sample bottle, 4 mmol of lead iodide was dissolved in a mixture of 5 mL of hydroiodic acid, 1 mL of hypophosphorous acid, and 4 mL of acetonitrile. 4 mmol of (R)-3-amino-1,2-propanediol was added to the mixture and sonicated at room temperature until a clear solution was obtained. The open bottle was placed in a wide-mouth bottle filled with ethyl acetate and sealed. After one week of solvent exchange, the metal halide fiber crystals of (R)-3-amino-1,2-propanediol hydrated lead iodide gradually grew. 0.2 g of these metal halide fiber crystals was weighed and placed in a 250 mL beaker. 200 mL of ethyl acetate was added as a dispersant. The mixture was ultrasonically dispersed for 30 minutes. The mixture was then filtered through a 4.0 cm diameter nylon microporous filter membrane to obtain a non-woven membrane of metal halide fiber crystals with a diameter of 4.0 cm. The upper and lower surfaces of the non-woven membrane were sprayed with conductive silver paint and dried at room temperature for 20 minutes. The 0.05mm thick copper foil was cut into two strips of about 10cm long and 0.5cm wide as conductors, and respectively adhered to the upper and lower electrodes with conductive silver paste. Then, silica gel was slowly dripped on the surface of the device and dried for 5 hours to form a metal halide fiber crystal non-woven membrane piezoelectric device. The device structure is as follows Figure 1-1 、 Figure 1-2 shown.

[0072] Density functional theory calculations were used to characterize the mechanical properties and piezoelectric properties of the metal halide fiber crystals prepared in the embodiment. Density functional theory calculations were performed by the Vienna Ab initio Simulation Package (VASP) based on density functional theory plane pseudopotential waves. The generalized gradient approximation (GGA) of Perdew-Burke-Ernzerh (PBE) was used as the exchange correlation function to optimize the atomic positions. Based on the Monkhorst-Pack method, the energy cutoff was set to 500eV and the k-point was set to 5×2×1. The Flim-related zero-damping DFT-D3 method was used to consider the diffusion effect. The elastic and piezoelectric coefficients of the crystal were determined based on these calculation conditions. The Christoffel equation was then solved based on the elastic constant and density to obtain the sound velocity. The results are shown in Figure 2. Figure 2 As shown in Figure 2, the Young's modulus of the metal halide fiber crystal is 15.01-24.29 GPa, and its anisotropy is only 1.62. The maximum longitudinal wave velocity is 2.95 km / s, and the minimum longitudinal wave velocity is 2.47 km / s. Correspondingly, the maximum and minimum longitudinal acoustic impedances are 10.75 and 8.99 Mrayls, respectively. The piezoelectric coefficient matrix shows that the metal halide fiber crystal has three shear piezoelectric coefficients, whose values are d 14 =-25.02, d 25 =-11.29 and d 36 =-11.96.

[0073] The metal halide fiber crystals prepared in the embodiment were filtered to prepare a non-woven membrane. Figure 3-1 、 Figure 3-2 As shown, the cross-structured membrane between the fiber crystals can be achieved through simple filtration, thereby realizing the large-scale and simple preparation of size-controllable non-woven membranes.

[0074] The surface morphology of the metal halide fiber crystal nonwoven membrane prepared in the example was observed using a field emission scanning electron microscope. The crystal membrane was glued to the test bench with conductive glue, and gold was sprayed on the membrane surface to improve conductivity. The results are shown in Figure 2. Figure 4 As shown, the crystal membrane is composed of a cross-structure between fiber crystals, an irregular grid structure with gaps, and the diameter of the fiber crystal is about 1μm.

[0075] The human body sensing performance of the metal halide fiber crystal non-woven fabric film piezoelectric device prepared in the example was characterized using a piezoelectric testing system. The device was fixed at the heel and connected to an oscilloscope to collect the output signals when walking and stomping. The results are shown in Figure 2. Figure 5 As shown, the signal strength is about 5V when walking, and the signal strength is about 12V when stomping, which shows that the present invention has the application of human motion sensing.

[0076] The metal halide fiber crystal non-woven fabric membrane piezoelectric device prepared in the embodiment is excited by acoustic waves using a water-immersion ultrasonic probe, so that it generates corresponding electrical signals and is captured by an oscilloscope. Figure 6 As shown, before conducting ultrasonic testing experiments, the nonwoven membrane piezoelectric device was sealed with polyethylene terephthalate tape. The device was fixed to the side of a water tank and connected to a digital oscilloscope via copper wire. The ultrasonic probe was immersed in the water environment perpendicular to the device.

[0077] The metal halide fiber crystal non-woven fabric membrane piezoelectric device prepared in the example was acoustically excited using ultrasonic probes of different frequencies (2.5, 5.0, and 10.0 MHz). The device was excited by ultrasonic signals of frequencies of 2.5, 5, and 10 MHz, and the output signal was Fourier transformed for frequency analysis. The results are shown in FIG. Figure 7 As shown, the center frequencies of the output ultrasonic signals are 9.17, 5.16, and 2.74 MHz, respectively, and the corresponding frequency errors are 8.3%, 3.2%, and 9.6%, respectively, indicating that the invention basically maintains the original characteristic frequency of the ultrasonic signal and has high frequency reproducibility.

[0078] The acoustic excitation capability of the metal halide fiber crystal non-woven membrane piezoelectric device prepared in the embodiment was tested in pure water and seawater under different environments. A 10MHz ultrasonic probe was fixed at a distance of about 18mm from the device and the experiment was carried out in seawater and pure water. The results are shown in Figure 2. Figure 8 As shown, the output signal and signal-to-noise ratio in pure water are only 0.2V and 3.274, while the signal strength in seawater is increased by 7 times, with the output signal and signal-to-noise ratio being 1.43V and 15.677, respectively. This is due to the difference in acoustic impedance. This shows that the present invention has a high degree of acoustic impedance matching with seawater and has application potential in deep-sea ultrasonic detection.

[0079] The ability of the metal halide fiber crystal non-woven membrane piezoelectric device prepared in the embodiment to detect the distance of the sound source was characterized by changing the distance between the ultrasonic probe and the device. The device was fixed, the vertical distance between the ultrasonic probe and the device was changed, and its output signal was recorded. The results are shown in Figure 2. Figure 9 As shown, the change in the distance between the probe and the device will cause the time axis to move proportionally, that is, as the distance increases, the signal gradually moves backward on the time axis, and the signal strength decreases accordingly, indicating that the present invention can accurately record the position of the sound source.

[0080] The acoustic wave detection capability of the metal halide fiber crystal non-woven membrane piezoelectric device prepared in the example was characterized by using seawater of different depths to respond to hydrostatic pressure. The probe and the device were fixed at the bottom of a 0.4m high water tank to detect ultrasonic signals in seawater of different depths, and then the sound intensity curve of the device was obtained as the hydrostatic pressure of the seawater changed. The results are shown in the figure. Figure 10 As shown, as the hydrostatic pressure gradually increases, the output signal shows a gradually increasing trend, and then shows a slowly decreasing trend, which reflects the high stress sensitivity of the device and indicates that the present invention has extremely high sensitivity to the hydrostatic pressure of seawater.

[0081] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal, characterized in that The following steps are involved: (1) Using organic amine ligands and inorganic ligands as raw materials, the solution is supersaturated and metal halide fiber crystals are precipitated through solvent diffusion method, solvent volatilization method or cooling crystallization method; (2) preparing the metal halide fiber crystals obtained in step (1) into a non-woven fiber membrane by suction filtration, wherein the fiber crystals have a structural feature of cross-texture; (3) Electrodes and wires are added to both sides of the non-woven fiber membrane prepared in step (2), and the non-woven membrane piezoelectric device is made by encapsulating it with silica gel.

2. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, characterized in that The organic amine ligand is a chiral organic amine containing a hydroxyl group, such as (R)-3-amino-1,2-propylene glycol, (S)-3-amino-1,2-propylene glycol, D-cyclohexylglycine, (1R, 2S)-2-phenylcyclopropylamine, (1S, 2R)-aminoindanol or (S)-N-Boc-3-hydroxypyrrolidine; the inorganic ligand is a metal salt such as lead iodide, lead bromide, cadmium bromide, copper bromide, lead chloride, cadmium chloride or copper chloride.

3. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, characterized in that The metal halide fiber crystal is a non-centrosymmetric, one-dimensional fiber crystal with a space group of P212121. The diameter of the fiber crystal is in the range of 1-100 microns and the length is in the range of 1-500 microns.

4. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, characterized in that The metal halide fiber crystal has elastic bending ability. Under external stress conditions, the crystal can be bent and deformed without destroying the crystal structure. After the external force is removed, the crystal returns to its original state. The non-woven fiber membrane is flexible and can be bent by applying appropriate external force. After the external force is removed, it returns to its original state without causing destructive damage.

5. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, characterized in that The non-woven membrane piezoelectric device is based on a non-woven fiber membrane with piezoelectric effect, with electrodes sprayed or pasted on both sides of the membrane, and wires connecting the electrodes to form a sandwich-type device, with packaging material as the packaging layer; the electrodes include silver, copper, platinum, and graphite, which are materials with excellent electrical conductivity; the wires include silver, copper, and platinum, which are materials with excellent electrical conductivity; the potting materials include silicone, polydimethylsiloxane, and polylactic acid polymer materials.

6. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, characterized in that The method for preparing the metal halide fiber crystal comprises the following steps: (1) dissolving an inorganic ligand in an acidic solvent to obtain solution A; (2) adding an organic amine ligand to solution A, adding a reagent that can dissolve the organic amine, and heating or ultrasonicating to obtain a clear solution B; (3) adding an antisolvent that can fully volatilize and diffuse in the container, placing the open sample bottle of Solution B into the container containing the antisolvent and sealing it, so that Solution B and the antisolvent diffuse into each other; (4) Solvent diffusion exchange or slow cooling to supersaturate the solution to obtain fibrous crystals; (5) After removing the solvent from the fibrous crystals, metal halide fibrous crystals are obtained; The molar ratio of metal ions to organic amines in the fiber crystals is 1:1; In step (1), the acidic solvent is one of hydroiodic acid, hypophosphorous acid, hydrochloric acid, and hydrobromic acid, or a mixed solution thereof; The reagent capable of dissolving the organic amine in step (2) is an organic solvent such as acetonitrile, methanol, isopropanol, or water; In the step (3), the anti-solvent that can fully volatilize and diffuse in the container is ethyl acetate.

7. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 6, characterized in that When the inorganic ligand is lead iodide and the organic amine ligand is (R)-3-amino-1,2-propylene glycol, the method for preparing the chiral metal halide fiber crystal material is: Step 1, dissolving lead iodide in a mixed solution of hydroiodic acid, hypophosphorous acid and acetonitrile to obtain solution A; Step 2: adding the organic amine ligand (R)-3-amino-1,2-propanediol to solution A, and ultrasonicating at room temperature to obtain a clear solution B; Step 3: Add ethyl acetate to the container, place the open sample bottle of Solution B into the container containing ethyl acetate, and seal it to allow Solution B and the antisolvent to diffuse into each other; Step 4: After solvent diffusion exchange, yellow fibrous crystals of (R)-3-amino-1,2-propylene glycol hydrated lead iodide are obtained; Step 5: The yellow fibrous crystals of (R)-3-amino-1,2-propanediol lead iodide hydrate are filtered, washed with ethyl acetate, and dried at room temperature to remove the solvent to obtain an aqueous crystalline product: (R)-3-amino-1,2-propanediol lead iodide hydrate.

8. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1, 6 or 7, characterized in that The method for preparing the non-woven fiber membrane comprises the following steps: Step 1: Weigh metal halide fiber crystals according to the size and thickness of the target film. To ensure that the target film is fully interwoven and maintains a certain degree of flexibility, the crystal film thickness should be in the range of 0.5-3 mm, and the amount of crystals used per square centimeter of film should be in the range of 0.01-0.1 g. The crystals are dispersed in a relatively volatile poor solvent for the crystals to obtain a mixture A. Step 2: Ultrasonic dispersion of mixture A to ensure that the fiber crystals are evenly dispersed in the solution, and the mixture A is filtered using a filter membrane of target diameter to obtain metal halide fiber crystal non-woven fiber membranes of different diameters and thicknesses.

9. The method for preparing a piezoelectric device of a non-woven fabric film of a metal halide fiber crystal according to claim 1 or 8, characterized in that The method for preparing a non-woven fiber membrane into a non-woven membrane piezoelectric device comprises the following steps: Step 1: spray or adhere electrodes to the upper and lower surfaces of the non-woven fiber membrane to obtain an electrode-covered non-woven fiber membrane C; Step 2: Glue the wires to the upper and lower electrode layers of the non-woven fiber membrane C to obtain a non-woven fiber membrane D with electrodes and connecting wires; Step 3: The potting material is spread all over the fiber crystal membrane and infiltrated into the interior of the non-woven fiber membrane. After the potting material is formed, a non-woven membrane piezoelectric device is obtained.

10. Application of a non-woven fabric film piezoelectric device of metal halide fiber crystal, characterized in that Applied to the field of flexible piezoelectric devices, research is conducted on the device's human body sensing response capabilities and underwater ultrasonic detection capabilities; The non-woven fabric membrane piezoelectric device has piezoelectricity, is sensitive to external stress stimulation, and can generate electrical signals in response to changes in human body movements. It is used in the field of sensing and can be used as a sensor to detect human body movements. The non-woven membrane piezoelectric device has piezoelectricity, is sensitive to external sound wave stimulation, can generate electrical signals in response to underwater sound wave stimulation, is used in the field of sound wave detection, and can generate sound wave signals in response to underwater sound wave stimulation.

Images