A multi-parameter testing method for dielectric properties of lead-free double perovskite material under high pressure

Abstract

The application provides a multi-parameter testing method for dielectric properties of a lead-free double perovskite material under high pressure, relates to the technical field of photoelectric functional materials, and realizes synchronous and accurate testing of dielectric multi-parameters and electric transport parameters, thereby providing a new experimental method for in-depth understanding of material structure property correlation. Pressure is used as a clean control means to avoid the problems of difficult control of quantitative proportion of mixed ions and introduction of impurities in ion doping. Through a combination of high-pressure in-situ testing and theoretical calculation, the transmission mechanism, control factors and dynamic performance of carriers are accurately revealed, and the regulation of pressure-induced structural changes on dielectric properties is determined. Through insulation protection layer design and three-electrode configuration, the testing errors caused by sample cavity leakage current and inaccurate sample thickness measurement are effectively solved, and the stability and precision of high-pressure testing are improved.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic functional materials technology, and more specifically, to a multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage. Background Technology

[0002] Against the backdrop of a global energy crisis and escalating environmental pollution, the development of low-carbon and green energy has become a global consensus. Photovoltaic technology, as a cutting-edge direction of green and low-carbon technological innovation, is a crucial measure to achieve carbon peaking and carbon neutrality. Currently, high-efficiency perovskite photovoltaic devices are mainly based on lead-based perovskite semiconductors. However, the presence of the heavy metal lead poses a potential hazard to the ecological environment and public health. Therefore, constructing a lead-free perovskite system that combines environmental compatibility and high stability has become a core scientific challenge that urgently needs to be overcome in this field.

[0003] Lead-free double perovskite materials possess characteristics such as environmental friendliness, excellent structural stability, and good bandgap controllability; their general chemical formula is A2B. + B 3+ X6, by replacing the +2 valence Pb in lead-based perovskites with +1 and +3 valence metal cations. 2+ This effectively eliminates lead toxicity. In 2017, Jiajun Luo et al. first synthesized a single crystal of the double perovskite material Cs2AgInCl6 and applied it to an ultraviolet photodetector. Zhang Lijun's research group at Jilin University designed more than 60 kinds of lead-free double perovskite materials through theoretical calculations, confirming that they have strong stability and tunable optical band gap, providing a theoretical basis for their application in the optoelectronic field.

[0004] However, the energy conversion efficiency of solar cells fabricated from lead-free double perovskite materials still needs improvement, and the core of material performance optimization lies in revealing the intrinsic relationship between structure and properties. Pressure, as a clean means of property control, can shorten the interatomic spacing, induce charge redistribution, change the crystal structure of the material, and form a new high-pressure phase without introducing impurities, thereby controlling the physicochemical properties of the material. Compared with ion doping technology, it is easier to achieve precise control.

[0005] To date, high-voltage research on lead-free double perovskite materials has mainly focused on optical property manipulation and bandgap evolution, while systematic studies on their electrical transport and dielectric properties under high voltage are rarely reported. Existing testing methods cannot achieve simultaneous and accurate testing of multiple dielectric parameters under high voltage conditions, nor can they establish structure-transport property-dielectric property relationships. Furthermore, there is a lack of effective methods for capturing superior high-voltage states, limiting the performance optimization and practical application of lead-free double perovskite materials. Developing a multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage is crucial to solving these problems. Therefore, this paper proposes a multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage. This method enables simultaneous and accurate testing of the electrical transport parameters and dielectric parameters of lead-free double perovskite material Cs2InSbX6 under high voltage conditions, reveals the carrier transport mechanism and dielectric property evolution law under high voltage, establishes the structure-transport property-dielectric property structure-property relationship, and explores methods for intercepting excellent high-voltage states. This provides an experimental basis and theoretical support for the optimization and modification of lead-free double perovskite materials and their application in optoelectronic devices.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high pressure, step 1: sample preparation and atmospheric pressure characterization, preparing Cs2InSbX6 samples, and performing atmospheric pressure characterization on the samples to confirm purity, crystal structure and basic physical properties. Step 2: Diamond anvil electrode preparation and assembly. Prepare metal electrodes and complete insulation treatment. Assemble them according to the parallel plate capacitor configuration. Use a three-electrode design to reduce test errors. Step 3: High-voltage in-situ AC impedance spectroscopy measurement. Place the sample in the sample chamber and gradually apply pressure to test the impedance spectrum data under different pressures and extract the electrical transport and dielectric parameters. Step 4: Theoretical calculation and mechanism analysis. The microstructure and properties of the sample under high pressure are calculated using material simulation software, and the structure-property relationship is established in combination with experimental data. Step 5: Exploration and interception of superior high-voltage states. Adjust high-voltage experimental parameters, explore optimal test conditions, and intercept the high-voltage states with excellent dielectric properties to atmospheric pressure.

[0008] As a preferred technical solution of the present invention, the Cs2InSbX6 sample in step 1 is prepared by solution method or high temperature solid phase method, and the atmospheric pressure characterization is performed by one or more of the following methods: X-ray diffraction, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, and Raman spectroscopy, to record the basic data of electrical transport and dielectric properties of the sample under atmospheric pressure.

[0009] As a preferred technical solution of the present invention, the electrode material in step 2 is selected as Mo or Cu. A metal thin film is deposited on the surface of a diamond anvil using a combination of magnetron sputtering and photolithography and etched into a preset shape. The preset shape is a structure in which a circular electrode and an arc-shaped electrode surround each other on the anvil surface, with the arc-shaped electrode wrapping around the circular electrode.

[0010] As a preferred technical solution of the present invention, the insulation treatment in step 2 involves depositing a 2-4 μm thick aluminum oxide insulating protective layer on the anvil surface and side surface of the diamond anvil, removing part of the insulating layer by photolithography and chemical etching to expose the electrode tip, and bonding copper wires with conductive silver paste to the electrode leads, and completing the fabrication by curing at 130-170°C for 1.5-2.5 hours.

[0011] As a preferred technical solution of the present invention, the pressure applied in step 3 is in the range of 0 to 20 GPa, and after each certain pressure is applied, the pressure is maintained for 20 to 30 minutes to ensure pressure stability. The test frequency range is 1 Hz to 10 MHz, and the contribution of grains and grain boundaries to dielectric response is separated by an impedance analyzer.

[0012] As a preferred technical solution of the present invention, the electrical transport parameters in step 3 include the type of conductive carriers, grain / grain boundary resistance, ionic conductivity, relaxation frequency and diffusion coefficient, and the dielectric parameters include the relative permittivity, phase angle, loss angle, real part and imaginary part of the permittivity.

[0013] As a preferred technical solution of the present invention, the material simulation software in step 4 is Materials Studio or VASP, and the calculation process uses GGA+PBE functional theory for crystal structure relaxation, with the total electron energy converging to 10. -5 eV, the interatomic interaction force converges to 0.01 eV / The plane wave cutoff energy was set to 500 eV. A 6×6×6 Monkhorst-Pack grid was used in the Brillouin zone. The band structure and optical properties were supplemented by analysis using the HSE06 hybrid functional.

[0014] As a preferred technical solution of the present invention, the theoretical calculations in step 4 include the ion migration path, activation energy, band structure, electronic state density and differential charge density of Cs2InSbX6 material under high pressure, which are used to reveal the influence mechanism of pressure-induced structural changes on carrier transport and dielectric properties.

[0015] As a preferred technical solution of the present invention, the high-pressure experimental parameters in step 5 include pressure magnitude, pressurization rate and holding time. The pressurization rate is 0.5 to 2 GPa / min. The interception of the excellent high-pressure state adopts a slow depressurization or gradient depressurization method, and the depressurization rate does not exceed 0.5 GPa / min. After interception, the dielectric properties of the sample are verified by characterization.

[0016] As a preferred technical solution of the present invention, the test method is applicable to the performance optimization test of lead-free double perovskite materials in solar cells, photodetectors and optoelectronic devices, and can realize the accurate construction of structure-transport properties-dielectric properties structure-property relationships.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention takes the lead-free double perovskite material Cs2InSbX6 as the research object, fills the gap in the systematic testing of the electrical transport and dielectric properties of lead-free double perovskite materials under high voltage, realizes the synchronous and accurate testing of multiple dielectric parameters and electrical transport parameters, and provides a brand-new experimental method for in-depth understanding of the structure-property relationship of materials.

[0018] Using pressure as a cleaning control method avoids the problems of difficult control of the quantitative ratio of mixed ions and the introduction of impurities in ion doping technology. By combining high-pressure in-situ testing with theoretical calculations, the transport mechanism, control factors and dynamic performance of charge carriers are accurately revealed, and the regulation law of pressure-induced structural changes on dielectric properties is clarified.

[0019] The fabrication and assembly process of diamond anvil cells was optimized. By designing an insulating protective layer and a three-electrode configuration, the test errors caused by sample cavity leakage current and inaccurate sample thickness measurement were effectively solved, improving the stability and accuracy of high-voltage testing. At the same time, an excellent high-voltage state interception method was explored, providing a new path for the performance optimization of lead-free double perovskite materials.

[0020] The testing methods and theoretical calculation methods used in this invention have been verified and are highly reliable. They have been widely used in high-voltage electrical research on various materials such as semiconductor materials and topological insulators. Furthermore, based on the applicant's long-term experience in high-voltage in-situ electrical transport testing, the invention is highly feasible. The test results can provide strong support for the practical application of lead-free double perovskite materials in solar cells, photodetectors, and optoelectronic devices. Attached Figure Description

[0021] Figure 1 A flowchart of the method provided by the present invention; Figure 2 A flowchart illustrating the specific steps of this invention; Figure 3 Electron micrograph of the Cs2InSbX6 sample provided by this invention; Figure 4 This is a schematic diagram of the bond length versus pressure curve provided by the present invention; Figure 5 A schematic diagram of the tilt angle versus pressure curve provided by the present invention; Figure 6 This is a schematic diagram of the sample spectrum provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0023] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] Example 1: A multi-parameter testing method for dielectric properties of lead-free double perovskite materials under high pressure. Step 1: Sample preparation and atmospheric pressure characterization. Prepare Cs2InSbX6 samples and perform atmospheric pressure characterization on the samples to confirm purity, crystal structure and basic physical properties. Step 2: Diamond anvil electrode preparation and assembly. Prepare metal electrodes and complete insulation treatment. Assemble them according to the parallel plate capacitor configuration. Use a three-electrode design to reduce test errors. Step 3: High-voltage in-situ AC impedance spectroscopy measurement. Place the sample in the sample chamber and gradually apply pressure to test the impedance spectrum data under different pressures and extract the electrical transport and dielectric parameters. Step 4: Theoretical calculation and mechanism analysis. The microstructure and properties of the sample under high pressure are calculated using material simulation software, and the structure-property relationship is established in combination with experimental data. Step 5: Exploration and interception of superior high-voltage states. Adjust high-voltage experimental parameters, explore optimal test conditions, and intercept the high-voltage states with excellent dielectric properties to atmospheric pressure.

[0025] In step 1, the Cs2InSbX6 sample was prepared by solution method or high-temperature solid-state method. The atmospheric pressure characterization was performed by one or more of the following methods: X-ray diffraction, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, and Raman spectroscopy. The basic data of electrical transport and dielectric properties of the sample under atmospheric pressure were recorded.

[0026] In step 2, the electrode material is selected as Mo or Cu. A metal thin film is deposited on the surface of a diamond anvil using a combination of magnetron sputtering and photolithography and etched into a preset shape. The preset shape is a structure in which a circular electrode and an arc-shaped electrode surround each other on the anvil surface, with the arc-shaped electrode wrapping around the circular electrode.

[0027] In step 2, the insulation treatment involves depositing a 2-4 μm thick aluminum oxide insulating protective layer on the anvil and sides of the diamond anvil. Part of the insulating layer is removed by photolithography and chemical etching to expose the electrode tip. The electrode leads are bonded to copper wires with conductive silver paste, and the fabrication is completed after curing at 130-170°C for 1.5-2.5 hours.

[0028] In step 3, the pressure applied ranges from 0 to 20 GPa. After each pressure is applied, the pressure is maintained for 20 to 30 minutes to ensure pressure stability. The test frequency ranges from 1 Hz to 10 MHz. The contribution of grains and grain boundaries to the dielectric response is separated by an impedance analyzer.

[0029] In step 3, the electrical transport parameters include the type of conductive carriers, grain / grain boundary resistance, ionic conductivity, relaxation frequency, and diffusion coefficient, while the dielectric parameters include the relative permittivity, phase angle, loss angle, and the real and imaginary parts of the permittivity.

[0030] In step 4, the materials simulation software used is Materials Studio or VASP. The calculation process employs GGA+PBE functional theory for crystal structure relaxation, and the total electron energy converges to 10. -5 eV, the interatomic interaction force converges to 0.01 eV / The plane wave cutoff energy was set to 500 eV. A 6×6×6 Monkhorst-Pack grid was used in the Brillouin zone. The band structure and optical properties were supplemented by analysis using the HSE06 hybrid functional.

[0031] The theoretical calculations in step 4 include the ion migration path, activation energy, band structure, electronic state density, and differential charge density of Cs2InSbX6 material under high pressure, which are used to reveal the mechanism by which pressure-induced structural changes affect carrier transport and dielectric properties.

[0032] In step 5, the high-pressure experimental parameters include pressure magnitude, pressurization rate, and holding time. The pressurization rate is 0.5–2 GPa / min. The interception of the excellent high-pressure state is carried out by slow depressurization or gradient depressurization, with a depressurization rate not exceeding 0.5 GPa / min. After interception, the dielectric properties of the sample are verified by characterization.

[0033] This testing method is applicable to the performance optimization testing of lead-free double perovskite materials in solar cells, photodetectors, and other optoelectronic devices, enabling precise construction of the structure-transport-dielectric property relationship. This invention combines high-pressure in-situ AC impedance spectroscopy with theoretical calculations to achieve simultaneous testing of multiple parameters related to the dielectric and electrical transport properties of lead-free double perovskite materials. Pressure shortens the interatomic spacing, induces charge redistribution between atoms, modulates the crystal structure, chemical bonds, and ion channels of the material, thereby altering carrier transport behavior and ultimately reflecting the evolution of dielectric parameters. Through high-pressure in-situ AC impedance spectroscopy, the contributions of grains and grain boundaries to the dielectric response are separated, accurately extracting multiple electrical transport and dielectric parameters. Simultaneously, by controlling high-pressure parameters, optimal high-pressure states are explored and captured, providing theoretical and experimental support for material performance optimization.

[0034] Example 2: A multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high pressure, comprising the following steps: Step 1: Sample preparation and atmospheric pressure characterization: Consult the literature on the synthesis of Cs2InSbBr6 materials, optimize the synthesis process, and use CsBr, InBr3, and SbBr3 as raw materials to prepare Cs2InSbBr6 single crystal samples by solution method; characterize the samples under atmospheric pressure by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible absorption spectroscopy to confirm that the samples are pure phase, have complete crystal structure, and have no obvious impurities, and record the atmospheric pressure dielectric parameters and basic electrical transport data of the samples.

[0035] Step 2: Diamond Anvil Cell (DAC) Electrode Fabrication and Assembly: Mo was selected as the electrode material. After cleaning and drying, the diamond anvil cell was placed in a vacuum chamber. Using Mo as the target material and argon as the working gas, a Mo metal thin film was deposited on the surface of the diamond anvil cell using magnetron sputtering under vacuum chamber pressure of 0.8–1.2 Pa and substrate temperature of 200–300 °C. The Mo thin film was etched into a predetermined shape using photolithography. The anvil cell electrode tips were circular and arc-shaped, with the arc-shaped tip surrounding the circular tip. The radius of the circular electrode was... The ratio of the inner diameter to the anvil radius is 1:4, the ratio of the inner diameter to the anvil radius of the arc-shaped electrode is 1:2, and the ratio of the outer diameter to the anvil radius is 4:5. Subsequently, an aluminum oxide insulating protective layer with a thickness of 2-4 μm is deposited by magnetron sputtering. The insulating layer on the anvil and sides is removed again by photolithography and chemical etching to expose the electrode tip. Copper wires are bonded to the exposed side electrodes and the pre-pressed T301 steel sheet gasket with conductive silver paste. The assembly is completed by curing at 150°C for 2 hours. The ratio of the radius of the central hole of the gasket to the radius of the circular window etched on the anvil insulating layer is 1.1:1.

[0036] Step 3: High-pressure in-situ AC impedance spectroscopy measurement: The Cs2InSbBr6 sample was placed in the sample chamber of a diamond anvil cell, and pressure was gradually applied using a hydraulic method, with a pressure range of 0–20 GPa. Pressure was maintained for 30 minutes at 2 GPa intervals to ensure pressure stability. In-situ impedance spectroscopy was performed using an AC impedance analyzer, with a test frequency range of 1 Hz–1 MHz, and the test temperature was kept at room temperature. Through impedance spectroscopy data fitting, it was determined that the conductive carrier type in the sample was ion-dominated. Grain resistance, grain boundary resistance, ionic conductivity, relative permittivity, loss angle, and relaxation frequency were extracted under different pressures, and the variation of each parameter with pressure was recorded.

[0037] Step 4: Theoretical Calculation and Mechanism Analysis: The Cs₂InSbBr₆ material under 0–20 GPa was simulated using VASP software. The crystal structure was fully relaxed using GGA+PBE functional theory, and the total electron energy converged to 10 GPa. -5 eV, the interatomic interaction force converges to 0.01 eV / The plane wave cutoff energy was set to 500 eV, and a 6×6×6 Monkhorst-Pack grid was used for the Brillouin zone. The band structure was calculated using the HSE06 hybrid functional, and the effect of pressure on the band gap was analyzed. The changes in interatomic charge distribution were revealed through differential charge density calculations. Combined with experimental data, the influence mechanism of pressure-induced crystal structure phase transition on carrier transport and dielectric properties was elucidated, and the structure-property relationship of Cs2InSbBr6 material structure-transport properties-dielectric properties was established.

[0038] Step 5: Exploration and interception of superior high-pressure state: The optimal test parameters were explored by adjusting the pressurization rate (0.5 GPa / min, 1 GPa / min, 2 GPa / min) and holding time (30 min, 60 min, 90 min). It was found that when the pressure was 12 GPa, the pressurization rate was 1 GPa / min, and the holding time was 60 min, the relative permittivity of the sample reached its maximum value, the dielectric loss was the lowest, and the structural stability was the best. The sample state under this pressure was intercepted to atmospheric pressure by slow depressurization (0.2 GPa / min). The intercepted sample still maintained excellent dielectric properties through XRD and impedance spectroscopy tests, achieving long-term optimization of material properties.

[0039] This invention combines high-pressure in-situ AC impedance spectroscopy with theoretical calculations to achieve simultaneous testing of multiple parameters related to the dielectric and electrotransport properties of lead-free double perovskite materials. Pressure shortens the interatomic spacing, induces charge redistribution between atoms, and modulates the crystal structure, chemical bonds, and ion channels of the material, thereby altering carrier transport behavior and ultimately reflecting changes in dielectric parameters. Through high-pressure in-situ AC impedance spectroscopy, the contributions of grains and grain boundaries to the dielectric response are separated, allowing for precise extraction of multiple electrotransport and dielectric parameters. Simultaneously, by controlling high-pressure parameters, optimal high-pressure states are explored and captured, providing theoretical and experimental support for optimizing material performance. Example 3: A multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high pressure, comprising the following steps: Step 1: Sample preparation and atmospheric pressure characterization: Cs2InSbI6 polycrystalline samples were prepared using CsI, InI3, and SbI3 as raw materials by a high-temperature solid-state method; atmospheric pressure characterization was performed by XRD, Raman spectroscopy, electrochemical workstation, etc., to confirm the sample purity and crystal structure, and to record the basic electrical transport and dielectric parameters under atmospheric pressure.

[0040] Step 2: Diamond anvil (DAC) electrode fabrication and assembly: Cu was selected as the electrode material, and the same magnetron sputtering, photolithography, insulating layer deposition and lead fabrication processes as in Example 1 were used to complete the fabrication and assembly of the diamond anvil electrode, ensuring good electrode contact and excellent insulation performance.

[0041] Step 3: High-pressure in-situ AC impedance spectroscopy measurement: The Cs2InSbI6 sample was placed in the sample chamber and a pressure of 0–15 GPa was applied, with a pressure holding time of 1 GPa for 20 minutes. The impedance spectrum under different pressures was measured using an AC impedance analyzer with a frequency range of 10 Hz–10 MHz. Parameters such as carrier type, ionic conductivity, relaxation frequency, and relative permittivity were extracted to analyze the regulatory law of pressure on dielectric properties.

[0042] Step 4: Theoretical Calculation and Mechanism Analysis: Using Materials Studio and VASP software, and in conjunction with the calculation parameters from Example 1, the ion migration path, activation energy, and electronic density of states of Cs2InSbI6 material under high pressure were calculated. Combined with experimental data, the intrinsic relationship between the carrier transport mechanism and the evolution of dielectric properties was revealed.

[0043] Step 5: Exploration and interception of superior high-pressure state: By adjusting the pressure and holding time, the optimal experimental conditions were explored. It was found that the dielectric properties of the sample were optimal when the pressure was 9 GPa and the holding time was 45 minutes. The superior high-pressure state was intercepted to atmospheric pressure using a gradient decompression method. Through characterization verification, the dielectric properties of the intercepted sample were better than those of the original sample under atmospheric pressure, providing experimental support for material modification.

[0044] Example 4: This invention utilizes a diamond anvil cell (DAC) to construct a controllable high-pressure environment. Combined with high-pressure in-situ AC impedance spectroscopy measurement technology and theoretical calculations, it achieves simultaneous testing of multiple parameters related to the dielectric and electrical transport properties of the lead-free double perovskite material Cs₂InSbX₆ (X=Br,Cl,I). Pressure shortens the interatomic spacing, induces a redistribution of interatomic charges, and modulates the material's crystal structure, chemical bonds, and ion channels, thereby altering the transport behavior of charge carriers (electrons and ions), ultimately reflected in the evolution of dielectric parameters. High-pressure in-situ AC impedance spectroscopy measurements separate the contributions of grains and grain boundaries to the dielectric response, accurately extracting multiple electrical transport and dielectric parameters. Combined with theoretical calculations using software such as Materials Studio and VASP, the intrinsic relationship between microstructural changes and macroscopic properties is revealed. Simultaneously, by controlling high-pressure parameters, superior high-pressure states are explored and captured, providing theoretical and experimental support for material performance optimization.

[0045] The complete working process of this invention revolves around sample preparation, test system construction, high-pressure in-situ testing, theoretical verification, and capture of optimal states, as detailed below: The first step is sample pretreatment and benchmark establishment: high-purity Cs2InSbX6 samples are prepared by solution method or high-temperature solid-state method. The samples are characterized at atmospheric pressure by means of X-ray diffraction, scanning electron microscopy and other means to confirm the crystal structure, purity and basic physical properties of the samples. Basic data of electrical transport and dielectric under atmospheric pressure are recorded to establish a benchmark for parameter comparison in subsequent high-voltage tests.

[0046] The second step is to build the test system: Mo or Cu is selected as the electrode material, and metal electrodes of a specific shape (circular and arc-shaped) are prepared on the surface of a diamond anvil by magnetron sputtering and photolithography. An aluminum oxide insulating protective layer is deposited and the exposed electrode tips are treated. The electrodes are assembled according to the configuration of a parallel plate capacitor, and a metal pad is used as the third electrode. The lead wires are cured to build a high-voltage test system with no leakage current and high precision.

[0047] The third step is high-pressure in-situ multi-parameter testing: The pretreated sample is placed in the diamond anvil cell sample chamber, and pressure of 0~20 GPa is gradually applied using hydraulic pressure. Each pressure level is held for 20~30 minutes to ensure pressure stability. Impedance spectrum data under different pressures are collected using an AC impedance analyzer (test frequency 1 Hz~10 MHz). The contributions of grains and grain boundaries are separated to determine the carrier type. Multiple parameters such as ionic conductivity, relative permittivity, and loss angle are extracted, and the dependence of parameters on pressure is established.

[0048] The fourth step is theoretical calculation and mechanism verification: using materials simulation software, crystal structure relaxation is completed using GGA+PBE functional analysis, and band structure is analyzed using HSE06 hybrid functional analysis. Microscopic parameters such as ion migration path and activation energy of the material under high pressure are calculated. The theoretical calculation results are compared with in-situ test data to reveal the regulation mechanism of pressure-induced structural changes on carrier transport and dielectric properties, and to construct the structure-transport properties-dielectric properties structure-property relationship.

[0049] The fifth step is the exploration and interception of the superior high-pressure state: by adjusting parameters such as the pressurization rate (0.5~2 GPa / min), holding time, and peak pressure, the high-pressure conditions that optimize the material's structural stability and dielectric properties are explored; by using a slow or gradient depressurization method (depressurization rate ≤0.5 GPa / min), the superior high-pressure state is intercepted to atmospheric pressure, and the interception effect is verified by atmospheric pressure characterization, thus completing the entire testing process.

[0050] Example 5: Evolution of the dielectric constant of Cs₂InSbBr₆ in the pressure range of 0–15 GPa and its microscopic mechanism. Procedure: Sample preparation and atmospheric pressure characterization: High-purity Cs₂InSbBr₆ powder was synthesized using a high-temperature solid-state method. CsBr, InBr₃, and SbBr₃ were mixed in stoichiometric ratios and calcined at 550 °C for 12 hours in an Ar atmosphere. The obtained sample was confirmed by XRD to have a cubic double perovskite structure (space group Fm-3m), and SEM showed a grain size of approximately 2–5 μm. UV-Vis measured a band gap of 2.1 eV. The relative permittivity ε was measured at 1 kHz under atmospheric pressure. ≈18, loss tanδ≈0.03.

[0051] The fabrication and assembly of diamond anvil cells involved depositing a 200 nm thick Mo film on the surfaces of two diamond anvil cells via magnetron sputtering. A central circular electrode (80 μm in diameter) and peripheral arc-shaped annular electrodes (30 μm wide, 20 μm spacing) were then etched using photolithography. Subsequently, a 3 μm thick Al₂O₃ insulating layer was deposited on the anvil surface. The electrode tips were exposed using photolithography and wet etching, and Cu leads were bonded using conductive silver paste. The mixture was then cured at 150 °C for 2 hours.

[0052] High-voltage in-situ AC impedance spectroscopy measurements were performed by placing Cs₂InSbBr₆ microcrystals in a NaCl pressure-transmitting medium and then inserting them into the DAC cavity. The pressure was increased to 15 GPa at a rate of 1 GPa / min, with each pressurization step followed by a 25-minute holding period. Impedance spectra were acquired using a Solartron 1260 impedance analyzer within the frequency range of 1 Hz–10 MHz. The grain resistance R_g (from 1.2 × 10⁻⁶) was separated by equivalent circuit fitting. 6 Ω decreased to 3.5 × 10 4 ε) and grain boundary resistance R_gb were found It reaches a peak frequency of 42 at 8 GPa, while the relaxation frequency shifts to higher frequencies.

[0053] Theoretical calculations and mechanism analysis were performed using VASP software, and GGA-PBE functional optimization was conducted to determine the crystal structure at 0, 5, 10, and 15 GPa. The results show that [InSbBr6] exhibits […] crystal structure under increasing pressure. 4- The increased octahedral distortion and shortened Br–Br distance lead to enhanced local dipole moments. HSE06 calculations show that the band gap is compressed from 2.1 eV to 1.6 eV, and the density of electronic states at the top of the valence band increases, promoting the polarization response. The differential charge density plot reveals that the charge redistribution around the Br ion is the main reason for the enhanced dielectric strength.

[0054] Excellent high-pressure state detection and interception were achieved. After holding at 8 GPa for 30 minutes, the pressure was slowly released to atmospheric pressure at 0.3 GPa / min. XRD analysis confirmed that the intercepted sample retained the cubic phase, and dielectric testing showed ε... ≈35 (a 94% improvement over the original), proving that high-pressure induced structural polarization can be partially preserved.

[0055] Example 6: Feasibility Verification of Halogen-Controlled High-Voltage Dielectric Properties and Atmospheric Pressure Interception of Cs₂InSbI₆ Objective: To compare the dielectric response limits of I-based materials under high voltage and to evaluate whether their high-voltage superior states can be effectively intercepted at ambient pressure for use in optoelectronic devices.

[0056] Procedure: Sample preparation: Cs₂InSbI₆ was synthesized via a high-temperature solid-state method (500℃, 10 h). XRD showed a slight impurity phase, which was purified by secondary sintering; SEM showed plate-like grains; band gap 1.7 eV; ε₀ under ambient pressure. ≈25 (because I - High polarizability.

[0057] High-voltage testing was performed, with the DAC assembled as before. The pressure was increased to 12 GPa (the upper limit was set to 12 GPa due to the poor mechanical stability of the I-based material). At 7 GPa, ε... The peak value reached 68, but was accompanied by a significant phase transition signal (a new relaxation peak appeared in the impedance spectrum). After holding the pressure for 30 minutes, the pressure was slowly released.

[0058] Upon interception and verification, the sample color changed from dark red to orange-red after depressurization. XRD showed that it was still a cubic phase, but the cell shrinkage was 1.8%. Dielectric testing yielded ε... ≈52, tanδ≈0.04; the photocurrent response is improved by 2.3 times, proving that the intercepted state has potential photovoltaic application value.

[0059] Mechanism analysis and VASP calculations show that an octahedral tilt phase transition (from Fm-3m to I4 / mmm) occurs at 7 GPa, enhancing ferroelectric polarization; after decompression, some strain is retained, maintaining a high polarization state.

[0060] Experimental Example 1 I. Experimental Objective A multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high pressure was adopted to complete the high-pressure in-situ dielectric and electrical transport parameter tests of Cs2InSbCl6 samples. By combining experimental data with theoretical calculations, the influence mechanism of pressure-induced structural changes on the dielectric properties of the material was revealed.

[0061] II. Experimental Principle Pressure modulates the crystal structure, chemical bonds, and ion channels of Cs₂InSbCl₆ material by shortening the interatomic spacing and inducing charge redistribution, thereby altering carrier transport behavior and ultimately affecting the evolution of dielectric parameters. This experiment combines diamond anvil cell high-pressure technology with in-situ AC impedance spectroscopy, employing a three-electrode design to reduce testing errors, separating the contributions of grains and grain boundaries to the dielectric response, and accurately extracting multiple electrical transport and dielectric parameters. Simultaneously, calculations using Materials Studio software are performed to construct structure-transport properties-dielectric properties relationships, enabling the simultaneous exploration and capture of superior high-pressure states.

[0062] III. Test Reagents CsCl (99.99% purity), InCl3 (99.99% purity), SbCl3 (99.99% purity), N,N-dimethylformamide (DMF, analytical grade), conductive silver paste, copper wires, alumina target, and Mo target.

[0063] IV. Test Procedure 4.1 Sample preparation and atmospheric pressure characterization Cs2InSbCl6 samples were prepared by solution method: CsCl, InCl3, and SbCl3 were dissolved in DMF in a molar ratio of 2:1:1 and stirred for 30 min until completely dissolved. The mixture was then placed in a 60℃ water bath for 2 h and reacted at a constant temperature. After cooling to room temperature, the mixture was centrifuged and the precipitate was dried in an 80℃ oven for 12 h to obtain Cs2InSbCl6 powder samples. The powder was then pressed into round samples with a diameter of 5 mm and a thickness of 0.3 mm.

[0064] The sample was characterized at atmospheric pressure using XRD, SEM, and Raman spectroscopy. XRD analysis confirmed a cubic crystal structure with no impurity peaks and a purity ≥99.5%. SEM showed uniform particle size with an average particle size of approximately 2 μm. Raman spectroscopy at 287 cm⁻¹... -1 The presence of a characteristic peak confirms the integrity of the sample structure. Simultaneously, the basic electrical transport and dielectric data of the sample under normal pressure were measured using an impedance analyzer, serving as a reference for subsequent high-voltage testing.

[0065] 4.2 Fabrication and Assembly of Diamond Anvil Electrodes Mo was selected as the electrode material. A Mo metal film was deposited on the surface of a diamond anvil using a combination of magnetron sputtering and photolithography. This film was then etched to form a structure with a circular electrode (0.8 mm in diameter) on the anvil and an arc-shaped electrode surrounding the circular electrode. A 3 μm thick alumina insulating protective layer was deposited on the anvil and sides of the diamond anvil. The insulating layer on the electrode tips was removed by photolithography and chemical etching, exposing the electrodes. Conductive silver paste was used to bond copper wires as electrode leads. The electrodes were then cured in a 150°C oven for 2 hours to complete the electrode fabrication. The electrodes were assembled in a parallel-plate capacitor configuration using a three-electrode design to reduce systematic errors during testing.

[0066] 4.3 High-voltage in-situ AC impedance spectroscopy measurement Cs₂InSbCl₆ wafer samples were placed in the sample chamber of a diamond anvil cell. Pressure was gradually applied using a high-pressure loading device, ranging from 0 to 20 GPa. Each 2 GPa increment was held for 25 minutes to ensure pressure stability. Afterward, impedance spectral data at this pressure was measured using an impedance analyzer (test frequency 1 Hz to 10 MHz). Through impedance spectral fitting, the contributions of grains and grain boundaries to the dielectric response were separated, and electrical transport parameters (conducting carrier type, grain / grain boundary resistance, ionic conductivity, relaxation frequency, diffusion coefficient) and dielectric parameters (relative permittivity, phase angle, loss angle, real and imaginary parts of the permittivity) were extracted. Each pressure point was tested three times, and the average value was used as the final data.

[0067] 4.4 Mechanism Analysis The microstructure and properties of Cs₂InSbCl₆ samples under high pressure were calculated using Materials Studio software. The calculations employed GGA+PBE functionals for crystal structure relaxation, and the total electron energy converged to 10. -5 eV, the interatomic interaction force converges to 0.01 eV / The plane wave cutoff energy was set to 500 eV, and a 6×6×6 Monkhorst-Pack grid was used for the Brillouin zone. The band structure and optical properties were supplemented by the HSE06 hybrid functional analysis. The calculations included ion migration paths, activation energies, band structures, electronic density of states, and differential charge density of the material under high pressure. Combined with experimental data, a structure-transport-dielectric property relationship was established, revealing the mechanism by which pressure-induced structural changes affect carrier transport and dielectric properties.

[0068] 4.5 Exploration and Interception of Excellent High-Pressure States High-pressure experimental parameters (pressure magnitude, pressurization rate, and holding time) were adjusted, with the pressurization rate set at 1 GPa / min. Optimal test conditions were gradually explored within the range of 0–20 GPa. Combined with dielectric parameter test results, the high-pressure range corresponding to superior dielectric properties was determined. A gradient depressurization method was used to capture the superior high-pressure state, with the depressurization rate controlled at 0.3 GPa / min. After depressurization to ambient pressure, the dielectric stability of the captured sample was verified by XRD, Raman spectroscopy, and impedance analysis.

[0069] V. Experimental Data Table 1: Relative permittivity (ε) of Cs₂InSbCl₆ under different pressures ) and dielectric loss (tanδ)

[0070] Table 2: Changes in grain and grain boundary resistance and ionic conductivity under high pressure

[0071] Table 3: Performance retention verification of the intercepted state after depressurization (depressurized to 0 GPa)

[0072] Data Analysis Dielectric properties change non-monotonicly with pressure. In the range of 0–12 GPa, ε The value increased significantly (from 28.5 to 72.4), while tanδ continued to decrease, indicating that the material's polarization ability was enhanced and energy loss was reduced.

[0073] After exceeding 12 GPa, ε The decline may be due to high-pressure-induced lattice distortion or local structural disorder, which weakens the dipole response capability.

[0074] Electrical transport mechanisms are dominated by grain boundary modulation. The decrease in grain boundary resistance (approximately 75%) was greater than that in grain resistance (approximately 79%), indicating that pressure effectively improved grain boundary contact and promoted ion migration.

[0075] The ionic conductivity peaks at 12 GPa (8.9 × 10⁻⁶). -7 The S / cm value is consistent with the peak value of the dielectric constant, indicating a strong coupling between carrier migration and dielectric polarization.

[0076] Excellent high-pressure states can be successfully intercepted After holding at 12 GPa, the pressure was slowly released, and the sample retained a high ε. (63.2) and low loss (0.023), XRD and Raman spectroscopy confirmed that the structure was basically stable (with only slight lattice compression).

[0077] The structural degradation that occurred after depressurization exceeded 14 GPa indicates the existence of a "performance-stability" window (8–12 GPa is the optimal range).

[0078] Theoretical calculations support experimental phenomena. Materials Studio calculations show that at 10–12 GPa, the Sb–Cl bond length shortens and the In / Sb octahedral tilt angle decreases, resulting in a slight narrowing of the band gap (from 2.8 eV to 2.5 eV). This enhances electron cloud overlap, promoting ion migration and interfacial polarization.

[0079] Differential charge density plots show Cl under high pressure - Increased surrounding electron density facilitates stronger ion-dipole interactions, enhancing dielectric response.

[0080] Conclusion: Cs2InSbCl6 exhibits optimal dielectric properties in the pressure range of 8–12 GPa: the relative permittivity is increased to over 70 and the dielectric loss is reduced to below 0.021, showing potential as a high-performance dielectric layer or optoelectronic functional material.

[0081] Pressure-induced structural optimization is the core mechanism for performance improvement: pressure, by compressing the lattice, improving grain boundary connectivity, and enhancing ion migration ability, synergistically increases the dielectric constant and suppresses losses.

[0082] The superior high-pressure state can be effectively captured by a gradient decompression strategy: after holding at 12 GPa, decompression at a rate of 0.3 GPa / min can yield a metastable high-pressure phase with stable structure and significantly better performance than the original sample.

[0083] This research provides a new path for the application of lead-free double perovskite materials in optoelectronic devices: through controllable high-voltage processing, the dielectric and optoelectronic properties can be synergistically optimized without introducing toxic elements (such as Pb), which is suitable for applications such as dielectric buffer layers in solar cells and low-noise photodetectors.

[0084] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage, characterized in that, The steps include: Step 1: Sample preparation and atmospheric pressure characterization. Prepare Cs2InSbX6 samples and perform atmospheric pressure characterization on the samples to confirm their purity, crystal structure and basic properties. Step 2: Preparation and assembly of diamond anvil cells. Prepare metal electrodes and complete insulation treatment. Assemble them according to the configuration of a parallel plate capacitor, using a three-electrode model. Step 3: High-voltage in-situ AC impedance spectroscopy measurement. Place the sample in the sample chamber and gradually apply pressure to test the impedance spectrum data under different pressures and extract the electrical transport and dielectric parameters. Step 4: Theoretical calculation and mechanism analysis. The microstructure and properties of the sample under high pressure are calculated using material simulation software, and the structure-property relationship is established in combination with experimental data. Step 5: Exploration and interception of superior high-voltage states. Adjust the high-voltage experimental parameters, debug the optimal test conditions, and intercept the high-voltage states with excellent dielectric properties to atmospheric pressure.

2. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage as described in claim 1, characterized in that, The Cs2InSbX6 sample described in step 1 is prepared by solution method or high-temperature solid-state method. The atmospheric pressure characterization is performed by one or more of the following methods: X-ray diffraction, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, and Raman spectroscopy, to record the basic electrical transport and dielectric data of the sample under atmospheric pressure.

3. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage as described in claim 1, characterized in that, In step 2, the electrode material is selected as Mo or Cu. A metal thin film is deposited on the surface of a diamond anvil using a combination of magnetron sputtering and photolithography and etched into a preset shape. The preset shape is a structure in which a circular electrode and an arc-shaped electrode surround each other on the anvil surface, with the arc-shaped electrode wrapping around the circular electrode.

4. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage as described in claim 1, characterized in that, The insulation treatment described in step 2 involves depositing a 2-4 μm thick aluminum oxide insulating protective layer on the anvil and sides of the diamond anvil. Part of the insulating layer is removed by photolithography and chemical etching to expose the electrode tip. The electrode leads are bonded to copper wires with conductive silver paste, and the fabrication is completed after curing at 130-170°C for 1.5-2.5 hours.

5. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to claim 1, characterized in that, The pressure applied in step 3 is in the range of 0 to 20 GPa. After each pressure is applied, the pressure is maintained for 20 to 30 minutes to ensure pressure stability. The test frequency range is 1 Hz to 10 MHz. The contribution of grains and grain boundaries to the dielectric response is separated by an impedance analyzer.

6. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to claim 1, characterized in that, The electrical transport parameters mentioned in step 3 include the type of conductive carriers, grain / grain boundary resistance, ionic conductivity, relaxation frequency, and diffusion coefficient. The dielectric parameters include the relative permittivity, phase angle, loss angle, real part, and imaginary part of the permittivity.

7. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to claim 1, characterized in that, The material simulation software mentioned in step 4 is Materials Studio or VASP. The calculation process uses GGA+PBE functionals for crystal structure relaxation, and the total electron energy converges to 10. -5 eV, the interatomic interaction force converges to 0.01 eV / The plane wave cutoff energy was set to 500 eV. A 6×6×6 Monkhorst-Pack grid was used in the Brillouin zone. The band structure and optical properties were supplemented by analysis using the HSE06 hybrid functional.

8. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to claim 1, characterized in that, The theoretical calculations in step 4 include the ion migration path, activation energy, band structure, electronic state density, and differential charge density of Cs2InSbX6 material under high pressure, which are used to reveal the mechanism by which pressure-induced structural changes affect carrier transport and dielectric properties.

9. The multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to claim 1, characterized in that, The high-pressure experimental parameters mentioned in step 5 include pressure magnitude, pressurization rate, and holding time. The pressurization rate is 0.5 to 2 GPa / min. The interception of the excellent high-pressure state is carried out by slow depressurization or gradient depressurization, and the depressurization rate does not exceed 0.5 GPa / min. After interception, the dielectric properties of the sample are verified by characterization.

10. A multi-parameter testing method for the dielectric properties of lead-free double perovskite materials under high voltage according to any one of claims 1 to 9, characterized in that, The test method described herein is applicable to performance optimization testing of lead-free double perovskite materials in applications such as solar cells, photodetectors, and optoelectronic devices.

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