An organic-inorganic hybrid dielectric switching material, and a preparation method and application thereof

Abstract

The application relates to the technical field of dielectric switch, and discloses an organic-inorganic hybrid dielectric switch material as well as a preparation method and application thereof, wherein the dielectric switch material is a CETAC MnCl crystal, the molecular formula is C 40 H 104 Cl 24 Mn4N8, the chemical formula weight is 1765.85, and CETAC is (2-chloroethyl)trimethylammonium chloride. The preparation method is as follows: (2-chloroethyl)trimethylammonium chloride and MnCl2 are added into water to be dissolved, a solution is obtained; and the solution is evaporated to obtain the CETAC MnCl crystal. The organic-inorganic hybrid dielectric switch material prepared by the application periodically changes with temperature, the switch period and the dielectric signal intensity remain almost unchanged after multiple cycles, and the material shows extremely high stability.

Description

Technical Field

[0001] This invention belongs to the field of dielectric switch technology, specifically relating to an organic-inorganic hybrid dielectric switch material, its preparation method, and its application. Background Technology

[0002] Dielectric switching materials are functional materials whose dielectric properties can be altered by external stimuli such as temperature, electric fields, and light. These materials can be used for switching control of devices such as information storage and sensors, and have a wide range of applications. Organic-inorganic hybrid dielectric switching materials are a new type of dielectric switching material developed in recent years. They are composed of organic amine cations and inorganic metal halide anions. These materials have advantages such as simple preparation, varied structures, and low cost. Furthermore, because the organic amine cations in the compound typically respond to external stimuli, undergoing structural phase transitions and exhibiting responses in physical properties such as light, electricity, magnetism, and heat, these materials can be used as multifunctional materials in various fields such as storage, switching, sensing, and energy conversion.

[0003] Currently, organic-inorganic hybrid dielectric switching materials have yielded a large number of dielectric switching materials with excellent individual properties by modifying the organic amine cations and inorganic anions. However, most commonly used dielectric switching materials are based on copper(I) halide perovskites, but the instability of copper(I) limits their practical applications. Therefore, there is an urgent need to develop a highly stable organic-inorganic hybrid dielectric switching material. Summary of the Invention

[0004] This invention provides an organic-inorganic hybrid dielectric switch material, its preparation method, and its application, which solves the problem that most commonly used dielectric switch materials are based on copper(I) halide perovskites, but the instability of copper(I) limits their practical application.

[0005] An organic-inorganic hybrid dielectric switching material, wherein the dielectric switching material is CETACMnCl crystal with the molecular formula C 40 H 104 Cl 24 Mn4N8, with a chemical formula weight of 1765.85, and CETAC (2-chloroethyl)trimethylammonium chloride; its unit cell parameters are... a =14.9483(5) Å, b = 15.8668(6) Å, c = 18.3414(7) Å, α = 88.664(3)°, β = 88.922(3)°, γ =73.869(3)°, crystal volume is 4177.5(3) ų, belonging to space group P-1.

[0006] Preferably, the dielectric switch material is in λ ex When excited at 360 nm, it exhibits green light emission at 528 nm.

[0007] Preferably, the crystal size is 0.2 × 0.2 × 0.3 mm.

[0008] The second objective of this invention is to protect the preparation method of the organic-inorganic hybrid dielectric switch material, specifically including the following steps: Dissolve (2-chloroethyl)trimethylammonium chloride and MnCl2 in water to obtain a solution; The resulting solution was evaporated to obtain CETACMnCl crystals.

[0009] Preferably, the ratio of (2-chloroethyl)trimethylammonium chloride:MnCl2:water is 2 mmol:1 mmol:1 mL.

[0010] Preferably, the dissolution method is ultrasonic dissolution or stirring dissolution.

[0011] Preferably, the evaporation condition is natural evaporation at room temperature.

[0012] Preferably, the obtained CETACMnCl crystals are filtered through a filter membrane and then baked at 45~55 ℃ for 2-6 hours until there are no water stains on the surface.

[0013] Preferably, the obtained CETACMnCl crystals are filtered through a filter membrane and then dried at 50 °C for 4 hours until there are no water stains on the surface.

[0014] A third objective of this invention is to protect the application of the aforementioned organic-inorganic hybrid dielectric switch material in the fabrication of dielectric switches.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The CETACMnCl synthesized in this invention is a novel organic-inorganic hybrid dielectric switching material, composed of (2-chloroethyl)trimethylammonium chloride cations and manganese chloride anions, forming a zero-dimensional perovskite structure. It has the following advantages:

[0016] 0. Thermogravimetric analysis of the synthesized CETACMnCl in this invention shows that it remains stable below 500 K, far above its phase transition temperature, indicating that the compound has excellent thermal stability and can withstand multiple phase transition cycles. Dielectric property studies show that the organic-inorganic hybrid dielectric switching material prepared in this invention exhibits extremely high stability as the temperature changes periodically, with the switching period and dielectric signal strength remaining almost unchanged after multiple cycles.

[0017] 0. Simple preparation and low cost: No complex equipment or harsh environment is required. Simply dissolve the two raw materials in water in a specific ratio, then evaporate to obtain CETACMnCl crystals. The raw materials are inexpensive, as both are commercially available, inexpensive compounds that are mass-produced, eliminating the need for additional synthesis and reducing costs.

[0018] 0. Multifunctional: The dielectric switching characteristics occur at 303~308 K, which is close to room temperature, which is beneficial for applications. It also has good green fluorescence properties, making it a multifunctional phase change material.

[0019] 0. Environmentally friendly: Contains no heavy metals and will not cause harm to human health or the environment. Attached Figure Description

[0020] Figure 1 This refers to the asymmetric unit in the single-crystal structure of CETACMnCl prepared in Example 1 of this invention; Figure 2 DSC (A) and TG (B) curves of CETACMnCl prepared in Example 1 of this invention; Figure 3 The XRD comparison diagram of CETACMnCl prepared in Example 1 of the present invention at 293 K is shown in the simulation and experimental XRD pattern. Figure 4 The temperature-dependent dielectric constant of CETACMnCl prepared in Example 1 of this invention at 1 MHz (A) and six different frequencies (B); Figure 5 The temperature-dependent dielectric loss of CETACMnCl prepared in Example 1 of this invention at 1 MHz (A) and six different frequencies (B); Figure 6 The recoverable dielectric switching characteristics of CETACMnCl prepared in Example 1 of this invention; Figure 7 CETACMnCl (Prepared in Example 1 of this invention) λ ex Solid-state fluorescence emission spectrum at 360 nm. Figure 7 A is λ em Excitation spectrum at 528 nm; corresponding coordinates in the CIE diagram (B); green fluorescence emitted under 365 nm UV light irradiation (C); Figure 8 The working principle diagram of the variable temperature dielectric switch made from CETACMnCl prepared in Example 1 of this invention. Detailed Implementation

[0021] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Unless otherwise specified, the methods described in the various embodiments of this invention are conventional methods. Unless otherwise specified, the materials and reagents used are commercially available.

[0023] Example 1 A method for preparing an organic-inorganic hybrid dielectric switch includes the following steps: (1) Add 3.16 g of (2-chloroethyl)trimethylammonium chloride and 1.26 g of MnCl2 to 10 mL of water, and sonicate at 500 W for 20 min to dissolve and obtain a clear solution.

[0024] (2) Evaporate the clear solution at room temperature, and obtain light green CETACMnCl crystals after 8 days.

[0025] (3) After filtering the CETACMnCl crystals with a single-crystal filter membrane, the CETACMnCl crystals with regular shapes were obtained. They were then dried at 45 °C for 6 h until there were no water stains on the surface, and placed in a vacuum desiccator for later use in crystal structure testing and property characterization. The single-crystal filter membrane was made of Jinteng polytetrafluoroethylene with a diameter of 0.45 μm.

[0026] Example 2 A method for preparing an organic-inorganic hybrid dielectric switch includes the following steps: (1) Add 3.16 g of (2-chloroethyl)trimethylammonium chloride and 1.26 g of MnCl2 to 10 mL of water, stir to dissolve, and obtain a clear solution.

[0027] (2) Evaporate the clear solution at room temperature and obtain light green CETACMnCl crystals after 14 days.

[0028] (3) After filtering the CETACMnCl crystals with a single-crystal filter membrane, the CETACMnCl crystals with regular shapes were obtained. They were then dried at 50 °C for 4 h until there were no water stains on the surface, and placed in a vacuum desiccator for later use in crystal structure testing and property characterization. The single-crystal filter membrane was made of Jinteng polytetrafluoroethylene with a diameter of 0.45 μm.

[0029] Example 3 A method for preparing an organic-inorganic hybrid dielectric switch includes the following steps: (1) Add 3.16 g of (2-chloroethyl)trimethylammonium chloride and 1.26 g of MnCl2 to 10 mL of water, and sonicate at 500 W for 30 min to obtain a clear solution.

[0030] (2) Evaporate the clear solution at room temperature, and obtain light green CETACMnCl crystals after 20 days.

[0031] (3) After filtering the CETACMnCl crystals with a single-crystal filter membrane, the CETACMnCl crystals with regular shapes were obtained. They were then dried at 55 °C for 2 h until there were no water stains on the surface, and placed in a vacuum desiccator for later use in crystal structure testing and property characterization. The single-crystal filter membrane was made of Jinteng polytetrafluoroethylene with a diameter of 0.45 μm.

[0032] Performance testing: Since the parameters of the CETACMnCl crystals prepared in Examples 2 and 3 are basically the same as those prepared in Example 1, the following tests will only take the CETACMnCl crystals prepared in Example 1 as an example.

[0033] The organic-inorganic hybrid dielectric switch material is CETACMnCl, a green crystalline material. Each smallest compound unit consists of two (2-chloroethyl)trimethylammonium cations, abbreviated as CETAC, and one manganese chloride anion, abbreviated as MnCl4, forming [CETAC]2. + [MnCl4]2 - It has a zero-dimensional perovskite structure, see Figure 1 Its cell parameters before the phase transition (278 K) are: a = 14.9483(5) Å, b = 15.8668(6) Å, c = 18.3414(7) Å, α = 88.664(3)°, β =88.922(3)°, γ = 73.869(3)°, the cell volume is 4177.5(3) ų, belonging to space group P-1; the cell parameters after the phase transition become a = 12.9001(7) Å, b = 12.9001(7) Å, c = 26.038(3) Å, α = 90°, β = 90°, γ =90°, the unit cell volume is 4333.1(5) ų, and the space group is I 41 / a See Table 1.

[0034] Table 1. Crystal structure data of CETACMnCl at 278 K and 333 K. 1. Thermal Analysis Differential scanning calorimetry (DSC) is a useful method for studying reversible phase transitions triggered by thermal stimuli. We performed DSC analysis on CETACMnCl, as shown in the following example. Figure 2 As shown in Figure A, a pair of thermal anomaly peaks were observed during the cooling and heating processes, appearing at 296 K and 310 K, respectively. The sharp shape of these peaks and the significant thermal hysteresis of approximately 14 K indicate that this is a first-order phase transition. Using the DSC curves, we applied Δ... S =Δ H The entropy change Δ is calculated from the / T relationship. S It is 74.4 J mol -1 K -1 enthalpy change Δ H Obtained by integrating the area of ​​the abnormal peak in the DSC. According to the Boltzmann equation Δ S = n Rln N Where R is the gas constant, N This represents the ratio of the number of geometrically distinguishable orientations. N The value is 7699. The calculation results indicate that this phase transition is a typical order-disorder transition. Furthermore, variable-temperature crystal structure testing further demonstrates that both anionic clusters and organic amines participate in the disordered motion. In addition, we performed thermogravimetric analysis in the temperature range of 300-800 K, see [link to thermogravimetric analysis]. Figure 2 B. The results showed that CETACMnCl remained stable below 500 K, much higher than its phase transition temperature, indicating that the compound has excellent thermal stability and can withstand multiple phase transition cycles.

[0035] 0. Purity Analysis like Figure 3 As shown, the XRD pattern of CETACMnCl powder tested at room temperature is a good match with the simulated XRD pattern of its single crystal structure, indicating that the purity of the corresponding phase is very high.

[0036] 0. Study on dielectric properties of CETACMnCl Based on the verification by DSC and single-crystal X-ray diffraction data, the reversible phase transition of CETACMnCl was confirmed. To further verify its reversible phase transition properties, we conducted dielectric constant and dielectric loss tests on the powder tablet samples, and the results are as follows: Figure 4As shown in Figure A, at a frequency of 1 MHz, the dielectric constant increases sharply from 4.2 to 5.2 as the temperature rises to around 310 K, and then remains relatively stable as the temperature continues to rise. This obvious step-like dielectric anomaly is consistent with the typical behavior of dielectric switching materials.

[0037] When the temperature drops to approximately 305 K, the dielectric constant rapidly recovers to the low dielectric state. The dielectric response of CETACMnCl exhibits some thermal hysteresis compared to DSC results during heating and cooling. This may be related to the different heating and cooling temperatures, but the trends are consistent. The reversible transition between the high and low dielectric states further confirms the temperature-triggered structural change. Crystal structure analysis reveals that the dielectric change of CETACMnCl is caused by the interaction of CETAC cations and [MnCl4]. 2- This is caused by the change in dipole moment during the ordered-disordered motion of anions. With periodic temperature variations, after multiple cycles, the switching period and dielectric signal strength remain almost constant, see [reference needed]. Figure 6 This demonstrates the extremely high stability of CETACMnCl.

[0038] Furthermore, we tested the dielectric response at different frequencies between 500 Hz and 1 MHz. The dielectric constant gradually increased as the frequency decreased, revealing a degree of frequency dependence (see [reference needed]). Figure 4 B. At the same temperature, the dielectric loss exhibits an anomaly and gradually decreases with increasing frequency, see... Figure 5 A, 5B.

[0039] 0. Optical Properties Study of CETACMnCl To investigate the luminescent properties of CETACMnCl, the crystal was ground and its solid-state powder fluorescence emission spectrum was measured, see [reference needed]. Figure 7 A; in λ ex At 360 nm excitation, the emission peak is at 528 nm; the CIE plot places the emission in the green light range, with corresponding color coordinates of (0.2615, 0.6651), see [reference needed]. Figure 7 B, the calculated color temperature, i.e., CCT, is 6716 K. To verify its fluorescence properties, the crystal was placed in a dark chamber and, under 365 nm ultraviolet light, CETACMnCl emitted visible green fluorescence. Figure 7 C. From a crystal structure perspective, [MnCl4] 2- The anion is its luminescent center because [MnCl4] 2- The anion is a tetrahedral complex, in which Mn 2+ Its electronic configuration is 3d 5 Due to the influence of the tetrahedral field, Mn 2+The 3d orbital splits, forming two sets of energy levels, namely t 2g and e g . t 2g The energy level is relatively low. e g The energy level is higher, and the energy difference between the two is called the crystal field splitting energy (Δ). Because Mn 2+ There are 5 3d electrons, which will fill the space according to Hund's rule. t 2g At higher energy levels, a high-spin state is formed. When [MnCl4]... 2- When anions are excited by light, one of them... t 2g Electrons can transition to e g At the energy level, a low-spin state is formed. When this electron falls back to... t 2g At this energy level, it emits green light. Therefore, [MnCl4] 2- The green light emitted by anions is due to electron transitions and emission caused by crystal field splitting.

[0040] 0. Application Temperature-sensitive dielectric materials have shown great promise in fields such as solar energy storage, smart switches, and sensors. Temperature-sensitive dielectric materials are smart materials that can automatically adjust their physical properties according to changes in external temperature. Among these materials, room-temperature dielectric switching materials are of great significance for the design of room-temperature smart devices because they can be triggered at room temperature and their dielectric constant can be adjusted within a relatively small temperature range. We pressed CETACMnCl single-crystal powder into a 13mm diameter, 1mm thick circular sample, coated both sides with silver paste as electrodes, led out wires, fabricated a device, and placed it in a variable-temperature environment to test its dielectric switching performance. (See...) Figure 8 A. The dielectric constant of this dielectric switch material is below 4.5 at T < 303 K and above 5.5 at T > 308 K. Therefore, we set a dielectric constant of 5 as the switching node to achieve the switching effect when the temperature changes. See [link to relevant documentation]. Figure 8 B. The specific principle is as follows: When the temperature is below 303 K, because the dielectric constant is less than 5, the capacitance of the capacitor is small, the impedance of the circuit is large, and the electrical signal is difficult to transmit, which is equivalent to the switch being closed; when the temperature is above 308 K, because the dielectric constant is greater than 5, the capacitance of the capacitor is large, the impedance of the circuit is small, and the electrical signal is easy to transmit, which is equivalent to the switch being open.

[0041] Compared with other temperature-varying dielectric materials, this material has the following advantages: 0. After more than 20 temperature cycles, the sample was not damaged and the signal did not attenuate, demonstrating good stability.

[0042] 0. The phase transition temperature is between 303 and 308 K, which is close to room temperature, and such variable temperature dielectric switch materials are relatively rare.

[0043] 0. It can be prepared by a simple solution method, which is convenient for large-scale production.

[0044] 0. The organic amines CETAC and MnCl2 contained therein are raw materials for large-scale production, which can be used directly in production. They are inexpensive, non-toxic, and suitable for industrial applications.

[0045] 0. Since it is solid both before and after the phase transition, there will be no leakage during use, and the requirements for device packaging are low.

[0046] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An organic-inorganic hybrid dielectric switch material, characterized in that, The dielectric switch material is CETACMnCl crystal, with the molecular formula C. 40 H 104 Cl 24 Mn4N8, with a chemical formula weight of 1765.85, consists of two (2-chloroethyl)trimethylammonium cations and one manganese chloride anion in each smallest compound unit; its unit cell parameters are... a = 14.9483(5) Å, b =15.8668(6) Å, c = 18.3414(7) Å, α = 88.664(3)°, β = 88.922(3)°, γ = 73.869(3)°, crystal volume is 4177.5(3) ų, belonging to space group P-1; the phase transition temperature of the CETACMnCl crystal is 303K~308K.

2. The organic-inorganic hybrid dielectric switch material according to claim 1, characterized in that, The dielectric switch material in λ ex When excited at 360 nm, it exhibits green light emission at 528 nm.

3. The organic-inorganic hybrid dielectric switch material according to claim 1, characterized in that, The crystal has a size of 0.2 × 0.2 × 0.3 mm.

4. The method for preparing an organic-inorganic hybrid dielectric switch material according to claim 1, characterized in that, Specifically, the following steps are included: Dissolve (2-chloroethyl)trimethylammonium chloride and MnCl2 in water to obtain a solution; The resulting solution was evaporated to obtain CETACMnCl crystals; The ratio of (2-chloroethyl)trimethylammonium chloride:MnCl2:water = 2 mmol:1 mmol:1 mL; After filtering the obtained CETACMnCl crystals with a filter membrane, they were dried at 45~55 ℃ for 2-6 hours until there were no water stains on the surface.

5. The method for preparing an organic-inorganic hybrid dielectric switch material according to claim 4, characterized in that, The dissolution method is ultrasonic dissolution or stirring dissolution.

6. The method for preparing an organic-inorganic hybrid dielectric switch material according to claim 4, characterized in that, The evaporation conditions are natural evaporation at room temperature.

7. The method for preparing an organic-inorganic hybrid dielectric switch material according to claim 4, characterized in that, The obtained CETACMnCl crystals were filtered through a filter membrane and then dried at 50 °C for 4 hours until there were no water stains on the surface.

8. The application of the organic-inorganic hybrid dielectric switch material according to claim 1 in the preparation of dielectric switches.

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