Predictive methods for high performance flexible thermoelectric materials and related devices

Abstract

The application discloses a kind of prediction method and related device for high-performance flexible thermoelectric material, comprising: twice optimization calculation is carried out to the initial crystal structure of material, the self-consistent calculation of material is carried out to optimized cell structure, and the charge density and total energy of material are obtained;Semiconductor material with band gap in preset energy band is screened out by band calculation;The stability of semiconductor material is evaluated using first-principle calculation;The ductility of material is evaluated using first-principle calculation, and high-ductility material is screened out;Phonon spectrum calculation is carried out to high-ductility material to obtain phonon density of states;Materials with low-frequency phonon density of states frequency less than preset frequency are preliminarily screened out;The calculation of electric transport property and thermal transport property is carried out to high-ductility material using first-principle calculation combined with Boltzmann transport equation to obtain the thermoelectric merit of material and screen out material with high ductility and good thermoelectric performance.

Description

Technical Field

[0001] This invention relates to the computational study of the thermal transport properties, electrical transport properties, and material stability of thermoelectric materials, and specifically to a prediction method and apparatus for high-performance flexible thermoelectric materials. Background Technology

[0002] Thermoelectric conversion technology, as a stable, zero-emission clean energy conversion technology, has received increasing attention. Thermoelectric devices utilize the Seebeck and Peltier effects to directly convert electrical energy into heat energy. This technology boasts excellent characteristics such as being clean and pollution-free, highly reliable, and having a long lifespan, showing great promise for applications in solar thermal, industrial waste heat, and thermoelectric power generation and refrigeration. In the past decade or so, extensive exploration and research have significantly improved the performance of laboratory-prepared thermoelectric materials; however, the performance of traditional thermoelectric (TE) material systems for practical commercial applications remains low. Therefore, finding novel thermoelectric material systems with excellent performance, low cost, and potential high performance is a crucial issue facing the field of thermoelectric materials. The efficiency of a thermoelectric material is determined by the dimensionless thermoelectric figure of merit (ZT), defined as... , where S, , , and T are the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, lattice thermal conductivity, and absolute temperature, respectively. Defined as the power factor, it characterizes the quality of electrical transport performance. However, the coupling of these transport parameters makes it difficult to significantly improve the ZT value of a material. To decouple these thermoelectric transport parameters and improve thermoelectric performance, researchers have proposed various concepts and methods, including improving the power factor of TE through strain engineering and band engineering at suitable operating temperatures. The expression for ZT shows that reducing... This is also key to improving the thermoelectric figure of merit of materials. And materials... This is usually related to the anharmonicity of the crystal lattice, which can be triggered by the introduction of weak bond elements, click atom vibrations, lone pairs of electrons, strong local bond asymmetry, etc. However, semiconductors with ultra-low lattice thermal conductivity are more likely to become high-performance thermoelectric materials.

[0003] In recent years, a series of emerging AB2X4 materials have attracted increasing attention. For example, ZnX2Z4 (X = Al, Ga; Z = S, Se, Te) materials exhibit excellent stability, high electron mobility, and low lattice thermal conductivity. These ternary materials not only effectively broaden the family of thermoelectric materials but also provide promising candidates for optoelectronic and thermoelectric materials. However, materials such as ZnIn2X4 (X = S, Se)... >2 W / mK limits the performance of thermoelectric materials. Therefore, when studying the performance of AB2X4 material, it is necessary to determine... The value of . When It is only when the ratio is less than 1 W / mK that it can be considered an excellent thermoelectric material.

[0004] The problem addressed in this invention is to systematically screen for promising high-performance flexible thermoelectric materials. To this end, the material structure, elasticity, electronic, and thermal transport properties were investigated within the framework of density functional theory (DFT). Phonon spectra were calculated to understand their thermodynamic stability. This study utilizes the semi-empirical Pugh's ratio method to screen for highly ductile materials. Furthermore, the thermal transport properties of phonons in the ShengBTE package are calculated based on the Boltzmann transport equation, which not only efficiently screens for materials with ultra-low lattice thermal conductivity but also provides a new method for developing efficient thermoelectric materials. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a prediction method and apparatus for screening high-performance flexible thermoelectric materials.

[0006] According to one aspect of the present invention, a prediction method for high-performance flexible thermoelectric materials is provided, comprising: Step S1: Perform two optimization calculations on the initial crystal structure of the material to obtain the optimized unit cell structure; the first calculation is a coarse-precision optimization calculation, and the second calculation is a high-precision optimization calculation. Step S2: Perform self-consistent calculations on the optimized cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screen out semiconductor materials with band gaps in the preset band gaps through band calculations. Step S3: Calculate the mechanical stability and thermodynamic stability of the semiconductor material and determine its formation enthalpy using first-principles calculations to obtain a stable material; Step S4: Calculate the ductility of the stable material using first-principles calculations to screen for highly ductile materials; Step S5: Calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; screen materials with low-frequency phonon density of states frequencies lower than a preset frequency to obtain low-frequency high-ductility materials; Step S6: Calculate the electrical and thermal transport properties of the low-frequency, high-ductility material using first-principles calculations to obtain the ZT value of the material.

[0007] In an alternative approach, step S1, the coarse-precision optimization calculation further includes: Step S11: Use VASP software to set the initial calculation parameters, where the high symmetry k point in three-dimensional space is 10 × 10 × 10; Step S12: Set EDIFFG to 10 in the INCAR parameters. -4 eV, EDIFF is 0.005 eV / Å, preliminary optimization calculations are performed on the cell edge lengths a, b, c and the internal atomic coordinates; The high-precision optimization calculation further includes: Step S13 involves optimizing the cell edge lengths a, b, and c, as well as the internal atomic coordinates, to obtain a stable cell structure. The force convergence criterion is set to be less than 0.001 eV / Å per atom, and the material's energy convergence criterion is 10... -8 eV; Step S14: Test the k-point and cutoff energy value. By comparing the calculation results under different k-points and cutoff energy values, determine the optimal k-point and cutoff energy value required in the calculation process.

[0008] In an alternative embodiment, step S2 further includes: Step S21: Optimize the cell volume and internal atomic coordinates using VASP software until the crystal structure is fully relaxed; wherein, the energy convergence criterion is set to 10. -8 eV, the convergence criterion for atomic positions is 0.001 eV / Å; during the optimization process, the cutoff energy is selected as 400 eV, and a 10 × 10 × 10 k-point grid is used based on the Monkhorst-Pack method; Step S22: Perform electronic non-self-consistent calculations on the material to obtain the band structure. Use first-principles methods and a PBE functional under the generalized gradient approximation to describe the exchange-related interactions between electrons. Step S23: Analyze the band structure and screen out materials with a band gap between 0.1 and 3.0 eV.

[0009] In an alternative embodiment, step S3 further includes: Step S31: Based on the unit cell structure selected in step S2, calculate the elastic constants; determine C using the space group of the structure. 11 >0, C 33 >0, C 44 >0, C 66 >0, (C 11 -C 12 )>0, (C 11 +C 33 -2C 13 )>0, [2(C 11 +C 12 )+C33 +4C 13 The standard for judging mechanical stability is 0; Step S32: Based on the cell structure selected in step S31, calculate the phonon spectrum; determine the dynamic stability of the material through the phonon density of states. Step S33: Based on the cell structure selected in step S32, perform ab initio molecular dynamics AIMD simulation, and determine the thermodynamic stability of the material through the AIMD simulation results.

[0010] In an alternative embodiment, step S4 further includes: According to the formula B V =(1 / 9)[2(C 11 + C 12 ) + C 33 + 4C 13 Calculate the bulk modulus B V ; According to the formula G V =(1 / 30)(M + 3C 11 - 3C 12 + 12C 44 + 6C 66 Calculate the shear modulus G V ,in, M = C 11 +C 12 + 2C 33 - 4C 13 ; According to the formula B R = C 2 / M and G R = 15{(18 B V / C 2 ) + [6 / (C 11 - C 12 )] + (6 / C 44 ) + (3 / C 66 )} -1 calculate B R and G R , where C 2 = (C 11 + C 12 C 33 - 2C 13 2; Calculate the average bulk modulus B H =(1 / 2)( B R + B V and mean shear modulus G H =(1 / 2)( G R + G V ); According to the formula Pugh's ratio = G H / B H Calculate Pugh's ratio; Materials with a Pugh's ratio less than 0.4 were screened to obtain candidate materials with high ductility and ultra-low lattice thermal conductivity.

[0011] In an alternative embodiment, step S5 further includes: A 2 × 2 × 2 supercell model of the target material was constructed to simulate the lattice structure on a larger scale; Based on the supercell model, a 2 × 2 × 2 k-point grid based on the Gamma method is used to calculate the phonon dispersion relation; The phonon spectrum of the target material is calculated based on the set supercell model, k-point grid, and MP parameters; wherein the MP parameters are 25 × 25 × 25. Based on the calculated phonon spectrum, materials with low-frequency phonon frequencies less than or equal to 2 THz were selected.

[0012] In an alternative embodiment, step S6 further includes: Step S61: Select a cutoff energy of 400 eV and use a 30 × 30 × 30 refined k-point grid based on the Monkhorst-Pack method; solve the electron Boltzmann transport equation using the BoltzTraP program to obtain the electrical transport physical parameters, wherein the physical parameters include the Seebeck coefficient (S), the ratio of electrical conductivity to relaxation time (σ / τ), and the ratio of electronic thermal conductivity to relaxation time (κ0 / τ); Step S62: Using the QUANTUM ESPRESSO (QE) + Electron-Phonon Wannier (EPW) program, the relaxation time is calculated via electro-acoustic coupling. During the calculation, the cutoff energy, energy convergence criterion, k-point grid, and q-point grid are set. The hole relaxation time and electron relaxation time are calculated by analyzing the corrections to single-phonon scattering and the Fermi-Dirac distribution function. Step S63: Calculate the electrical conductivity σ, power factor PF, and electronic thermal conductivity κ. e Among them, electronic thermal conductivity κ e The calculation formula is: ; Step S64: Obtain the phonon dispersion relation of the material using the supercell method; calculate the second-order and third-order force constants using a 3 × 3 × 3 supercell structure model; solve the phonon Boltzmann transport equation using ShengBTE code to calculate the lattice thermal conductivity κ of the material. L ; Verify materials with low thermal conductivity by screening based on Pugh's ratio and phonon frequency; Step S65, according to the formula Calculate the ZT value of the material in the temperature range of 300 K - 900 K.

[0013] In an alternative embodiment, in step S62, the formula for calculating the hole relaxation time is: in, , where is the Fermi-Dirac distribution function at the valence band peak; Let (h,k) be the energy of the quantum state (h,k). Boltzmann constant; T is temperature; The formula for calculating the electronic relaxation time is as follows: in, , is the Fermi-Dirac distribution function with the conduction band bottom; and This is the Fermi level calculated for holes and electrons in the EPW packet.

[0014] According to another aspect of the present invention, a predictive device for high-performance flexible thermoelectric materials is provided, comprising: The cell structure optimization module is used to perform two optimization calculations on the initial crystal structure of the material to obtain the optimized cell structure; the first is a coarse-precision optimization calculation, and the second is a high-precision optimization calculation. The self-consistent calculation and bandgap screening module is used to perform self-consistent calculations on the optimized cell structure, obtain the charge density and total energy of the material through sufficient structural relaxation, and screen out semiconductor materials with band gaps in a preset bandgap through bandgap calculations. The stability assessment module is used to assess the mechanical stability, thermodynamic stability, and formation enthalpy of the semiconductor material using first-principles calculations to obtain a stable material. The ductility testing module is used to perform ductility testing on the stable material using first principles to screen out materials with high ductility. The low-frequency phonon density of states screening module is used to calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; and to screen materials whose low-frequency phonon density of states frequency is less than a preset frequency to obtain low-frequency high-ductility materials. The thermoelectric performance calculation module is used to calculate the electrical and thermal transport properties of the low-frequency, high-ductility material using first-principles calculations to obtain the ZT value of the material.

[0015] In an alternative approach, step S1, the coarse-precision optimization calculation further includes: Step S11: Use VASP software to set the initial calculation parameters, where the high symmetry k point in three-dimensional space is 10 × 10 × 10; Step S12: Set EDIFFG to 10 in the INCAR parameters. -4 eV, EDIFF is 0.005 eV / Å, preliminary optimization calculations are performed on the cell edge lengths a, b, c and the internal atomic coordinates; The high-precision optimization calculation further includes: Step S13 involves optimizing the cell edge lengths a, b, and c, as well as the internal atomic coordinates, to obtain a stable cell structure. The force convergence criterion is set to be less than 0.001 eV / Å per atom, and the material's energy convergence criterion is 10... -8 eV; Step S14: Test the k-point and cutoff energy value. By comparing the calculation results under different k-points and cutoff energy values, determine the optimal k-point and cutoff energy value required in the calculation process.

[0016] In an alternative embodiment, step S2 further includes: Step S21: Optimize the cell volume and internal atomic coordinates using VASP software until the crystal structure is fully relaxed; wherein, the energy convergence criterion is set to 10. -8eV, the convergence criterion for atomic positions is 0.001 eV / Å; during the optimization process, the cutoff energy is selected as 400 eV, and a 10 × 10 × 10 k-point grid is used based on the Monkhorst-Pack method; Step S22: Perform electronic non-self-consistent calculations on the material to obtain the band structure. Use first-principles methods and a PBE functional under the generalized gradient approximation to describe the exchange-related interactions between electrons. Step S23: Analyze the band structure and screen out materials with a band gap between 0.1 and 3.0 eV.

[0017] In an alternative embodiment, step S3 further includes: Step S31: Based on the unit cell structure selected in step S2, calculate the elastic constants; determine C using the space group of the structure. 11 >0, C 33 >0, C 44 >0, C 66 >0, (C 11 -C 12 )>0, (C 11 +C 33 -2C 13 )>0, [2(C 11 +C 12 )+C 33 +4C 13 The standard for judging mechanical stability is 0; Step S32: Based on the cell structure selected in step S31, calculate the phonon spectrum; determine the dynamic stability of the material through the phonon density of states. Step S33: Based on the cell structure selected in step S32, perform ab initio molecular dynamics AIMD simulation, and determine the thermodynamic stability of the material through the AIMD simulation results.

[0018] In an alternative embodiment, step S4 further includes: According to the formula B V =(1 / 9)[2(C 11 + C 12 ) + C 33 + 4C 13 Calculate the bulk modulus B V ; According to the formula G V =(1 / 30)(M + 3C 11 - 3C 12 + 12C 44+ 6C 66 Calculate the shear modulus G V ,in, M = C 11 +C 12 + 2C 33 - 4C 13 ; According to the formula B R = C 2 / M and G R = 15{(18 B V / C 2 ) + [6 / (C 11 - C 12 )] + (6 / C 44 ) + (3 / C 66 )} -1 calculate B R and G R , where C 2 = (C 11 + C 12 C 33 - 2C 13 2 ; Calculate the average bulk modulus B H =(1 / 2)( B R + B V and mean shear modulus G H =(1 / 2)( G R + G V ); According to the formula Pugh's ratio = G H / B H Calculate Pugh's ratio; Materials with a Pugh's ratio of less than 0.4 were screened to obtain materials with high ductility and ultra-low lattice thermal conductivity.

[0019] In an alternative embodiment, step S5 further includes: A 2 × 2 × 2 supercell model of the target material was constructed to simulate the lattice structure on a larger scale; Based on the supercell model, a 2 × 2 × 2 k-point grid based on the Gamma method is used to calculate the phonon dispersion relation; The phonon spectrum of the target material is calculated based on the set supercell model, k-point grid, and MP parameters; wherein the MP parameters are 25 × 25 × 25. Based on the calculated phonon spectrum, materials with low-frequency phonon frequencies less than or equal to 2 THz were selected.

[0020] In an alternative embodiment, step S6 further includes: Step S61: Select a cutoff energy of 400 eV and use a 30 × 30 × 30 refined k-point grid based on the Monkhorst-Pack method; solve the electron Boltzmann transport equation using the BoltzTraP program to obtain the electrical transport physical parameters, wherein the physical parameters include the Seebeck coefficient (S), the ratio of electrical conductivity to relaxation time (σ / τ), and the ratio of electronic thermal conductivity to relaxation time (κ0 / τ); Step S62: Using the QUANTUM ESPRESSO (QE) + Electron-Phonon Wannier (EPW) program, the relaxation time is calculated via electro-acoustic coupling. During the calculation, the cutoff energy, energy convergence criterion, k-point grid, and q-point grid are set. The hole relaxation time and electron relaxation time are calculated by analyzing the corrections to single-phonon scattering and the Fermi-Dirac distribution function. Step S63: Calculate the electrical conductivity σ, power factor PF, and electronic thermal conductivity κ. e Among them, electronic thermal conductivity κ e The calculation formula is: ; Step S64: Obtain the phonon dispersion relation of the material using the supercell method; calculate the second-order and third-order force constants using a 3 × 3 × 3 supercell structure model; solve the phonon Boltzmann transport equation using ShengBTE code to calculate the lattice thermal conductivity κ of the material. L ; Verify materials with low thermal conductivity by screening based on Pugh's ratio and phonon frequency; Step S65, according to the formula Calculate the ZT value of the material in the temperature range of 300 K - 900 K.

[0021] In an alternative embodiment, in step S62, the formula for calculating the hole relaxation time is: in, , where is the Fermi-Dirac distribution function at the valence band peak; Let (h,k) be the energy of the quantum state (h,k). Boltzmann constant; T is temperature; The formula for calculating the electronic relaxation time is as follows: in, , is the Fermi-Dirac distribution function with the conduction band bottom; and This is the Fermi level calculated for holes and electrons in the EPW packet.

[0022] According to the solution provided by the present invention, the method includes: Step S1, performing two optimization calculations on the initial crystal structure of the material to obtain an optimized unit cell structure; wherein, the first is a coarse-precision optimization calculation and the second is a high-precision optimization calculation; Step S2, performing self-consistent calculations on the optimized unit cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screening out semiconductor materials with band gaps in a preset energy band through band structure calculations; Step S3, using first-principles calculations to determine the mechanical stability, thermodynamic stability, and formation enthalpy of the semiconductor material to obtain a stable material; Step S4, using first-principles calculations to perform ductility tests on the stable material to screen out highly ductile materials; Step S5, performing phonon spectrum calculations on the highly ductile material to obtain the phonon density of states; screening out materials with low-frequency phonon density of states frequencies lower than a preset frequency to obtain low-frequency highly ductile materials; Step S6, using first-principles calculations to perform electrical transport properties and thermal transport properties on the low-frequency highly ductile material to obtain the ZT value of the material. This invention investigates the structural, elastic, electronic, and transport properties within the framework of density functional theory (DFT). To understand its thermodynamic stability, phonon spectra were calculated. The semi-empirical Pugh's ratio method was used to screen for materials with high ductility. Furthermore, based on the Boltzmann transport equation, the thermal transport properties of phonons in the ShengBTE package were calculated, which not only efficiently screens materials with ultra-low lattice thermal conductivity but also provides a new method for developing efficient thermoelectric materials. By judging band gap, stability, ductility, and phonon spectra, thermoelectric materials with ultra-low lattice thermal conductivity in AB2X4 materials are predicted. The calculations can be automated, offering advantages such as high speed and accurate results. Simultaneously, theoretical calculations can provide a basis and guidance for experimental research, enabling in-depth analysis and understanding of the microscopic intrinsic mechanisms of thermoelectric materials, thereby promoting the improvement of thermoelectric conversion efficiency.

[0023] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a prediction method for high-performance flexible thermoelectric materials according to an embodiment of the present invention is shown. Figure 2 A schematic diagram of the screening and judgment process according to an embodiment of the present invention is shown; Figure 3 A schematic diagram illustrating the computational techniques of an embodiment of the present invention is shown; Figure 4 The graph showing the relationship between Pugh's ratio and lattice thermal conductivity at 300 K for samples meeting the criteria of this invention is illustrated in an embodiment of the invention. Figure 5 The band diagrams of ZnAg2Br4 and ZnAg2I4 according to embodiments of the present invention are shown; Figure 6 The graph shows the relationship between the thermoelectric figure of merit of ZnAg2Br4 and ZnAg2I4 according to embodiments of the present invention and the changes in temperature and carrier concentration. Figure 7 A schematic diagram of the framework of a prediction device for high-performance flexible thermoelectric materials according to an embodiment of the present invention is shown. Detailed Implementation

[0025] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0026] Figure 1 A flowchart illustrating a prediction method for high-performance flexible thermoelectric materials according to an embodiment of the present invention is shown. Specifically, as... Figure 1 As shown, it includes the following steps: Step S1 involves performing two optimization calculations on the initial crystal structure of the material to obtain the optimized unit cell structure; the first calculation is a coarse-precision optimization calculation, and the second is a high-precision optimization calculation. This is to facilitate obtaining stable lattice constants and atomic positions of the material.

[0027] In an alternative approach, step S1, the coarse-precision optimization calculation further includes: Step S11: Use VASP software to set the initial calculation parameters, where the high symmetry k point in three-dimensional space is 10 × 10 × 10; Step S12: Set EDIFFG to 10 in the INCAR parameters. -4 eV, EDIFF is 0.005 eV / Å, preliminary optimization calculations are performed on the cell edge lengths a, b, c and the internal atomic coordinates; The high-precision optimization calculation further includes: Step S13 involves optimizing the cell edge lengths a, b, and c, as well as the internal atomic coordinates, to obtain a stable cell structure. The force convergence criterion is set to be less than 0.001 eV / Å per atom, and the material's energy convergence criterion is 10... -8 eV; Step S14: Test the k-point and cutoff energy value. By comparing the calculation results under different k-points and cutoff energy values, determine the optimal k-point and cutoff energy value required in the calculation process.

[0028] Step S2 involves performing self-consistent calculations on the optimized cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screening out semiconductor materials with band gaps in a preset band gap through band calculations.

[0029] In an alternative embodiment, step S2 further includes: Step S21: Optimize the cell volume and internal atomic coordinates using VASP (Vienna Ab-initio Simulation Package) software until the crystal structure is fully relaxed; the energy convergence criterion is set to 10. -8 eV, the convergence criterion for atomic positions is 0.001 eV / Å; during the optimization process, the cutoff energy is selected as 400 eV, and a 10 × 10 × 10 k-point grid is used based on the Monkhorst-Pack method; Step S22: Perform electronic non-self-consistent calculations on the material to obtain the band structure. Use first-principles methods and a PBE functional under the generalized gradient approximation to describe the exchange-related interactions between electrons. Step S23: Analyze the band structure and screen out materials with a band gap between 0.1 and 3.0 eV.

[0030] Step S3: Calculate the mechanical stability and thermodynamic stability of the semiconductor material and determine the formation enthalpy using first-principles calculations to obtain a stable material.

[0031] In an alternative embodiment, step S3 further includes: Step S31: Based on the unit cell structure selected in step S2, calculate the elastic constants; determine C using the space group of the structure. 11 >0, C 33 >0, C 44 >0, C 66 >0, (C 11 -C 12 )>0, (C 11 +C 33 -2C 13 )>0, [2(C 11 +C 12 )+C 33 +4C 13 The standard for judging mechanical stability is 0; Step S32: Based on the cell structure selected in step S31, calculate the phonon spectrum; determine the dynamic stability of the material through the phonon density of states. Step S33: Based on the cell structure selected in step S32, perform ab initio molecular dynamics AIMD simulation, and determine the thermodynamic stability of the material through the AIMD simulation results.

[0032] Step S4: Calculate the ductility of the stable material system using first-principles calculations to screen for highly ductile materials.

[0033] In an alternative embodiment, step S4 further includes: According to the formula B V =(1 / 9)[2(C 11 + C 12 ) + C 33 + 4C 13 Calculate the bulk modulus B V ; According to the formula G V =(1 / 30)(M + 3C 11 - 3C 12 + 12C 44 + 6C 66 Calculate the shear modulus G V ,in, M = C 11 +C 12 + 2C 33 - 4C 13 ; According to the formula B R = C 2 / M and GR = 15{(18 B V / C 2 ) + [6 / (C 11 - C 12 )] + (6 / C 44 ) + (3 / C 66 )} -1 calculate B R and G R , where C 2 = (C 11 + C 12 C 33 - 2C 13 2 ; Calculate the average bulk modulus B H =(1 / 2)( B R + B V and mean shear modulus G H =(1 / 2)( G R + G V ); According to the formula Pugh's ratio = G H / B H Calculate Pugh's ratio; Materials with a Pugh's ratio less than 0.4 were screened to obtain materials with high ductility and ultra-low lattice thermal conductivity. When G... H / B H A Pugh's ratio <0.571 indicates high ductility, while a ratio <0.571 indicates higher brittleness. Therefore, ultra-low lattice thermal conductivity can be screened by selecting materials with a Pugh's ratio less than 0.4.

[0034] Step S5: Calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; screen materials with low-frequency phonon density of states frequencies lower than a preset frequency to obtain low-frequency high-ductility materials.

[0035] In an alternative embodiment, step S5 further includes: A 2 × 2 × 2 supercell model of the target material was constructed to simulate the lattice structure on a larger scale; Based on the supercell model, a 2 × 2 × 2 k-point grid based on the Gamma method is used to calculate the phonon dispersion relation; The phonon spectrum of the target material is calculated based on the set supercell model, k-point grid, and MP parameters; wherein the MP parameters are 25 × 25 × 25. Based on the calculated phonon spectrum, materials with low-frequency phonon frequencies less than or equal to 2 THz were selected.

[0036] Step S6: Calculate the electrical and thermal transport properties of the highly ductile material using first-principles calculations and the Boltzmann equation to obtain the ZT value of the material.

[0037] In an alternative embodiment, step S6 further includes: Step S61: Select a cutoff energy of 400 eV and use a 30 × 30 × 30 refined k-point grid based on the Monkhorst-Pack method; solve the electron Boltzmann transport equation using the BoltzTraP program to obtain the electrical transport physical parameters, wherein the physical parameters include the Seebeck coefficient (S), the ratio of electrical conductivity to relaxation time (σ / τ), and the ratio of electronic thermal conductivity to relaxation time (κ0 / τ); Step S62: Using the QUANTUM ESPRESSO (QE) + Electron-Phonon Wannier (EPW) program, the relaxation time is calculated via electro-acoustic coupling. During the calculation, the cutoff energy, energy convergence criterion, k-point grid, and q-point grid are set. The hole relaxation time and electron relaxation time are calculated by analyzing the corrections to single-phonon scattering and the Fermi-Dirac distribution function. Step S63: Calculate the electrical conductivity σ, power factor PF, and electronic thermal conductivity κ. e Among them, electronic thermal conductivity κ e The calculation formula is: ; Step S64: Obtain the phonon dispersion relation of the material using the supercell method; calculate the second-order and third-order force constants using a 3 × 3 × 3 supercell structure model; solve the phonon Boltzmann transport equation using ShengBTE code to calculate the lattice thermal conductivity κ of the material. L ; Verify materials with low thermal conductivity by screening based on Pugh's ratio and phonon frequency; Step S65, according to the formula Calculate the ZT value of the material in the temperature range of 300 K - 900 K.

[0038] In an alternative embodiment, in step S62, the formula for calculating the hole relaxation time is: in, , where is the Fermi-Dirac distribution function at the valence band peak; Let (h,k) be the energy of the quantum state (h,k). Boltzmann constant; T is temperature; The formula for calculating the electronic relaxation time is as follows: in, , is the Fermi-Dirac distribution function with the conduction band bottom; and This is the Fermi level calculated for holes and electrons in the EPW packet.

[0039] To more clearly illustrate the solutions provided by the above embodiments of the present invention, the following is combined with... Figure 2 The flowchart for the filtering and judgment process shown below, and as follows Figure 3 The calculation technique is illustrated in the diagram shown.

[0040] Step one: The atomic ratio is defined as A:B:X = 1:2:4, and there are a total of 450 initial crystal structures to classify. The space groups are all cubic.

[0041] Step two involves using first-principles calculations to perform bandgap screening on semiconductor materials with band gaps between 0.1 and 3.0 eV. 241 materials met the criteria. After assessing the stability of the materials through mechanical properties, kinetic stability, and thermodynamic properties, 110 materials remained suitable.

[0042] Step 3: Under the premise of stability, calculate the ductility of the material. 67 materials with a Pugh's ratio < 0.4 were selected.

[0043] Step four: Calculate the phonon spectrum and, based on the phonon density of states, screen for low-frequency phonons with frequencies ≤ 2 THz. Twelve materials meet the screening criteria. An embodiment of this invention uses ZnAg₂Br₄ and ZnAg₂I₄ materials: Step 5: ZnAg2Br4 and ZnAg2I4 materials meet all the above conditions. In the electrical transport calculations for ZnAg2Br4 and ZnAg2I4, the k-point is set to 30 × 30 × 30.

[0044] Step six: To ensure the convergence and accuracy of phonon calculations, all calculations were performed in a large 3 × 3 × 3 supercell containing 216 atoms. Second-order interatomic force constants (IFCs) were calculated using Phonopy code based on density functional perturbation theory. Third-order IFCs were calculated using the finite displacement method. In these calculations, the sixth nearest neighbor (7 Å) was chosen as the cutoff distance for the three-atom interaction. The transport properties of phonons in the ShengBTE package were calculated based on the Boltzmann transport equation. Phonon dispersion information was obtained from the obtained second-order force constants, and then the phonon group velocity, Green's Eisen constant, and thermal properties of the material were derived from the phonon dispersion information.

[0045] Step 7, combine the above power factor PF and electronic thermal conductivity. lattice thermal conductivity Substituting temperature T into the formula The ZT value of the material is obtained.

[0046] like Figures 4 to 6 As shown, this embodiment utilizes first-principles calculations and Boltzmann transport theory to automatically screen thermoelectric materials with stable band gaps of 0.1–3.0 eV, Pugh's ratio < 0.4, and low-frequency phonon state density ≤ 2 THz. The lattice thermal conductivity of the materials is then obtained. With a strength <1 W / mK, it possesses potentially excellent thermoelectric properties. Furthermore, the calculation process is fast and yields accurate results. This provides theoretical guidance for exploring ternary semiconductor materials and can screen for various high-performance thermoelectric materials, thereby reducing time and computational costs.

[0047] According to the solution provided by the present invention, the method includes: Step S1, performing two optimization calculations on the initial crystal structure of the material to obtain an optimized unit cell structure; wherein, the first is a coarse-precision optimization calculation and the second is a high-precision optimization calculation; Step S2, performing self-consistent calculations on the optimized unit cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screening out semiconductor materials with band gaps in a preset energy band through band structure calculations; Step S3, using first-principles calculations to determine the mechanical stability, thermodynamic stability, and formation enthalpy of the semiconductor material to obtain a stable material; Step S4, using first-principles calculations to perform ductility tests on the stable material to screen out highly ductile materials; Step S5, performing phonon spectrum calculations on the highly ductile material to obtain the phonon density of states; screening out materials with low-frequency phonon density of states frequencies lower than a preset frequency to obtain low-frequency highly ductile materials; Step S6, using first-principles calculations to perform electrical transport properties and thermal transport properties on the low-frequency highly ductile material to obtain the ZT value of the material. This invention investigates the structural, elastic, electronic, and transport properties within the framework of density functional theory (DFT). To understand its thermodynamic stability, phonon spectra were calculated. The semi-empirical Pugh's ratio method was used to screen for materials with high ductility. Furthermore, based on the Boltzmann transport equation, the thermal transport properties of phonons in the ShengBTE package were calculated, which not only efficiently screens materials with ultra-low lattice thermal conductivity but also provides a new method for developing efficient thermoelectric materials. By judging band gap, stability, ductility, and phonon spectra, thermoelectric materials with ultra-low lattice thermal conductivity in AB2X4 materials are predicted. The calculations can be automated, offering advantages such as high speed and accurate results. Simultaneously, theoretical calculations can provide a basis and guidance for experimental research, enabling in-depth analysis and understanding of the microscopic intrinsic mechanisms of thermoelectric materials, thereby promoting the improvement of thermoelectric conversion efficiency.

[0048] Figure 7 A schematic diagram of a prediction device for high-performance flexible thermoelectric materials according to an embodiment of the present invention is shown. The prediction device for high-performance flexible thermoelectric materials includes: a cell structure optimization module 710, a self-consistent calculation and bandgap screening module 720, a stability judgment module 730, a ductility testing module 740, a low-frequency phonon state density screening module 750, and a thermoelectric performance calculation module 760.

[0049] The cell structure optimization module 710 is used to perform two optimization calculations on the initial crystal structure of the material to obtain the optimized cell structure; the first calculation is a coarse-precision optimization calculation, and the second calculation is a high-precision optimization calculation. The self-consistent calculation and bandgap screening module 720 is used to perform self-consistent calculations on the optimized cell structure, obtain the charge density and total energy of the material through sufficient structural relaxation, and screen out semiconductor materials with band gaps in a preset bandgap through bandgap calculations. The stability determination module 730 is used to determine the mechanical stability, thermodynamic stability and formation enthalpy of the semiconductor material using first principles, so as to obtain a stable material. The ductility testing module 740 is used to perform ductility testing on the stable material using first principles to screen out materials with high ductility. The low-frequency phonon density of states screening module 750 is used to calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; and to screen materials whose low-frequency phonon density of states frequency is less than a preset frequency to obtain low-frequency high-ductility materials. The thermoelectric performance calculation module 760 is used to calculate the electrical and thermal transport properties of the low-frequency high-ductility material using first-principles calculations to obtain the ZT value of the material.

[0050] In an alternative approach, step S1, the coarse-precision optimization calculation further includes: Step S11: Use VASP software to set the initial calculation parameters, where the high symmetry k point in three-dimensional space is 10 × 10 × 10; Step S12: Set EDIFFG to 10 in the INCAR parameters. -4 eV, EDIFF is 0.005 eV / Å, preliminary optimization calculations are performed on the cell edge lengths a, b, c and the internal atomic coordinates; The high-precision optimization calculation further includes: Step S13 involves optimizing the cell edge lengths a, b, and c, as well as the internal atomic coordinates, to obtain a stable cell structure. The force convergence criterion is set to be less than 0.001 eV / Å per atom, and the material's energy convergence criterion is 10... -8 eV; Step S14: Test the k-point and cutoff energy value. By comparing the calculation results under different k-points and cutoff energy values, determine the optimal k-point and cutoff energy value required in the calculation process.

[0051] In an alternative embodiment, step S2 further includes: Step S21: Optimize the cell volume and internal atomic coordinates using VASP software until the crystal structure is fully relaxed; wherein, the energy convergence criterion is set to 10. -8eV, the convergence criterion for atomic positions is 0.001 eV / Å; during the optimization process, the cutoff energy is selected as 400 eV, and a 10 × 10 × 10 k-point grid is used based on the Monkhorst-Pack method; Step S22: Perform electronic non-self-consistent calculations on the material to obtain the band structure. Use first-principles methods and a PBE functional under the generalized gradient approximation to describe the exchange-related interactions between electrons. Step S23: Analyze the band structure and screen out materials with a band gap between 0.1 and 3.0 eV.

[0052] In an alternative embodiment, step S3 further includes: Step S31: Based on the unit cell structure selected in step S2, calculate the elastic constants; determine C using the space group of the structure. 11 >0, C 33 >0, C 44 >0, C 66 >0, (C 11 -C 12 )>0, (C 11 +C 33 -2C 13 )>0, [2(C 11 +C 12 )+C 33 +4C 13 The standard for judging mechanical stability is 0; Step S32: Based on the cell structure selected in step S31, calculate the phonon spectrum; determine the dynamic stability of the material through the phonon density of states. Step S33: Based on the cell structure selected in step S32, perform ab initio molecular dynamics AIMD simulation, and determine the thermodynamic stability of the material through the AIMD simulation results.

[0053] In an alternative embodiment, step S4 further includes: According to the formula B V =(1 / 9)[2(C 11 + C 12 ) + C 33 + 4C 13 Calculate the bulk modulus B V ; According to the formula G V =(1 / 30)(M + 3C 11 - 3C 12 + 12C 44+ 6C 66 Calculate the shear modulus G V ,in, M = C 11 +C 12 + 2C 33 - 4C 13 ; According to the formula B R = C 2 / M and G R = 15{(18 B V / C 2 ) + [6 / (C 11 - C 12 )] + (6 / C 44 ) + (3 / C 66 )} -1 calculate B R and G R , where C 2 = (C 11 + C 12 C 33 - 2C 13 2 ; Calculate the average bulk modulus B H =(1 / 2)( B R + B V and mean shear modulus G H =(1 / 2)( G R + G V ); According to the formula Pugh's ratio = G H / B H Calculate Pugh's ratio; Materials with a Pugh's ratio of less than 0.4 were screened to obtain materials with high ductility and ultra-low lattice thermal conductivity.

[0054] In an alternative embodiment, step S5 further includes: A 2 × 2 × 2 supercell model of the target material was constructed to simulate the lattice structure on a larger scale; Based on the supercell model, a 2 × 2 × 2 k-point grid based on the Gamma method is used to calculate the phonon dispersion relation; The phonon spectrum of the target material is calculated based on the set supercell model, k-point grid, and MP parameters; wherein the MP parameters are 25 × 25 × 25. Based on the calculated phonon spectrum, materials with low-frequency phonon frequencies less than or equal to 2 THz were selected.

[0055] In an alternative embodiment, step S6 further includes: Step S61: Select a cutoff energy of 400 eV and use a 30 × 30 × 30 refined k-point grid based on the Monkhorst-Pack method; solve the electron Boltzmann transport equation using the BoltzTraP program to obtain the electrical transport physical parameters, wherein the physical parameters include the Seebeck coefficient (S), the ratio of electrical conductivity to relaxation time (σ / τ), and the ratio of electronic thermal conductivity to relaxation time (κ0 / τ); Step S62: Using the QUANTUM ESPRESSO (QE) + Electron-Phonon Wannier (EPW) program, the relaxation time is calculated via electro-acoustic coupling. During the calculation, the cutoff energy, energy convergence criterion, k-point grid, and q-point grid are set. The hole relaxation time and electron relaxation time are calculated by analyzing the corrections to single-phonon scattering and the Fermi-Dirac distribution function. Step S63: Calculate the electrical conductivity σ, power factor PF, and electronic thermal conductivity κ. e Among them, electronic thermal conductivity κ e The calculation formula is: ; Step S64: Obtain the phonon dispersion relation of the material using the supercell method; calculate the second-order and third-order force constants using a 3 × 3 × 3 supercell structure model; solve the phonon Boltzmann transport equation using ShengBTE code to calculate the lattice thermal conductivity κ of the material. L ; Verify materials with low thermal conductivity by screening based on Pugh's ratio and phonon frequency; Step S65, according to the formula Calculate the ZT value of the material in the temperature range of 300 K - 900 K.

[0056] In an alternative embodiment, in step S62, the formula for calculating the hole relaxation time is: in, , where is the Fermi-Dirac distribution function at the valence band peak; Let (h,k) be the energy of the quantum state (h,k). Boltzmann constant; T is temperature; The formula for calculating the electronic relaxation time is as follows: in, , is the Fermi-Dirac distribution function with the conduction band bottom; and This is the Fermi level calculated for holes and electrons in the EPW packet.

[0057] According to the solution provided by the present invention, the method includes: Step S1, performing two optimization calculations on the initial crystal structure of the material to obtain an optimized unit cell structure; wherein, the first is a coarse-precision optimization calculation and the second is a high-precision optimization calculation; Step S2, performing self-consistent calculations on the optimized unit cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screening out semiconductor materials with band gaps in a preset energy band through band structure calculations; Step S3, using first-principles calculations to perform mechanical stability, thermodynamic stability calculations, and formation enthalpy determination on the semiconductor material to obtain a stable material; Step S4, using first-principles calculations to perform ductility tests on the stable material to screen out highly ductile materials; Step S5, performing phonon spectrum calculations on the highly ductile material to obtain the phonon density of states; screening out materials with low-frequency phonon density of states frequencies lower than a preset frequency to obtain low-frequency highly ductile materials; Step S6, using first-principles calculations to perform electrical transport properties and thermal transport properties on the low-frequency highly ductile material to obtain the ZT value of the material.

[0058] This invention investigates the structural, elastic, electronic, and transport properties within the framework of density functional theory (DFT). To understand its thermodynamic stability, phonon spectra were calculated. The semi-empirical Pugh's ratio method was used to screen for materials with high ductility. Furthermore, based on the Boltzmann transport equation, the thermal transport properties of phonons in the ShengBTE package were calculated, which not only efficiently screens materials with ultra-low lattice thermal conductivity but also provides a new method for developing efficient thermoelectric materials. By judging band gap, stability, ductility, and phonon spectra, thermoelectric materials with ultra-low lattice thermal conductivity in AB2X4 materials are predicted. The calculations can be automated, offering advantages such as high speed and accurate results. Simultaneously, theoretical calculations can provide a basis and guidance for experimental research, enabling in-depth analysis and understanding of the microscopic intrinsic mechanisms of thermoelectric materials, thereby promoting the improvement of thermoelectric conversion efficiency.

[0059] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination of all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed can be employed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose. Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims that list several devices, several of these devices may be embodied by the same hardware item. Unless otherwise specified, the steps in the above embodiments should not be construed as limiting the order of execution.

Claims

1. A prediction method for high-performance flexible thermoelectric materials, characterized in that, include: Step S1: Perform two optimization calculations on the initial crystal structure of the material to obtain the optimized unit cell structure; the first calculation is a coarse-precision optimization calculation, and the second calculation is a high-precision optimization calculation. Step S2: Perform self-consistent calculations on the optimized cell structure to obtain the charge density and total energy of the material through sufficient structural relaxation; and screen out semiconductor materials with band gaps in the preset band gap range of 0.1-3.0 eV through band gap calculations. Step S3: Calculate the mechanical stability and thermodynamic stability of the semiconductor material and determine its formation enthalpy using first-principles calculations to obtain a stable material; Step S4: Calculate the ductility test of the stable material using first principles, and screen materials with a Pugh's ratio less than 0.4 to obtain a high-ductility material; Step S5: Calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; screen materials with a low-frequency phonon density of states less than or equal to 2 THz to obtain low-frequency high-ductility materials; Step S6: Calculate the electrical and thermal transport properties of the low-frequency, high-ductility material using first-principles calculations. This material has the characteristics of an energy band of 0.1-3.0 eV, a Pugh's ratio of less than 0.4, and a phonon density of states frequency of less than or equal to 2 THz, and obtain the ZT values ​​of these materials.

2. The prediction method for high-performance flexible thermoelectric materials according to claim 1, characterized in that, In step S1, the coarse-precision optimization calculation further includes: Step S11: Use VASP software to set the initial calculation parameters, where the high symmetry k point in three-dimensional space is 10 × 10 × 10; Step S12: Set EDIFFG to 10 in the INCAR parameters. -4 eV, EDIFF is 0.005 eV / Å, preliminary optimization calculations are performed on the cell edge lengths a, b, c and the internal atomic coordinates; The high-precision optimization calculation further includes: Step S13 involves optimizing the cell edge lengths a, b, and c, as well as the internal atomic coordinates, to obtain a stable cell structure. The force convergence criterion is set to be less than 0.001 eV / Å per atom, and the material's energy convergence criterion is 10... -8 eV; Step S14: Test the k-point and cutoff energy value. By comparing the calculation results under different k-points and cutoff energy values, determine the optimal k-point and cutoff energy value required in the calculation process.

3. The prediction method for high-performance flexible thermoelectric materials according to claim 1 or 2, characterized in that, Step S2 further includes: Step S21: Optimize the cell volume and internal atomic coordinates using VASP software until the crystal structure is fully relaxed; wherein, the energy convergence criterion is set to 10. -8 eV, the convergence criterion for atomic positions is 0.001 eV / Å; during the optimization process, the cutoff energy is selected as 400 eV, and a 10 × 10 × 10 k-point grid is used based on the Monkhorst-Pack method; Step S22: Perform electronic non-self-consistent calculations on the material to obtain the band structure. Use first-principles methods and a PBE functional under the generalized gradient approximation to describe the exchange-related interactions between electrons. Step S23: Analyze the band structure and screen out materials with a band gap between 0.1 and 3.0 eV.

4. The prediction method for high-performance flexible thermoelectric materials according to claim 3, characterized in that, Step S3 further includes: Step S31: Based on the unit cell structure selected in step S2, calculate the elastic constants; determine C using the space group of the structure. 11 > 0, C 33 > 0, C 44 > 0, C 66 > 0, (C 11 -C 12 ) > 0, (C 11 +C 33 -2C 13 ) > 0, [2(C 11 +C 12 )+C 33 +4C 13 The standard for judging mechanical stability is 0. Step S32: Based on the cell structure selected in step S31, calculate the phonon spectrum; determine the dynamic stability of the material through the phonon density of states. Step S33: Based on the cell structure selected in step S32, perform ab initio molecular dynamics AIMD simulation, and determine the thermodynamic stability of the material through the AIMD simulation results.

5. The prediction method for high-performance flexible thermoelectric materials according to claim 4, characterized in that, Step S4 further includes: According to the formula B V =(1 / 9)[2(C 11 + C 12 ) + C 33 + 4C 13 Calculate the bulk modulus B V ; According to the formula G V =(1 / 30)(M + 3C 11 - 3C 12 + 12C 44 + 6C 66 Calculate the shear modulus G V ,in, M = C 11 + C 12 + 2C 33 - 4C 13 ; According to the formula B R = C 2 / M and G R = 15{(18 B V / C 2 ) + [6 / (C 11 - C 12 )] + (6 / C 44 ) + (3 / C 66 )} -1 calculate B R and G R , where C 2 = (C 11 + C 12 C 33 - 2C 13 2 ; Calculate the average bulk modulus B H =(1 / 2)( B R + B V and mean shear modulus G H =(1 / 2)( G R + G V ); According to the formula Pugh's ratio = G H / B H Calculate Pugh's ratio; Materials with a Pugh's ratio less than 0.4 were screened to obtain candidate materials with high ductility and ultra-low lattice thermal conductivity.

6. The prediction method for high-performance flexible thermoelectric materials according to claim 1, characterized in that, Step S5 further includes: A 2 × 2 × 2 supercell model of the target material was constructed to simulate the lattice structure on a larger scale; Based on the supercell model, a 2 × 2 × 2 k-point grid based on the Gamma method is used to calculate the phonon dispersion relation; The phonon spectrum of the target material is calculated based on the set supercell model, k-point grid, and MP parameters; wherein the MP parameters are 25 × 25 × 25. Based on the calculated phonon spectrum, materials with low-frequency phonon frequencies less than or equal to 2 THz were selected.

7. The prediction method for high-performance flexible thermoelectric materials according to claim 1, characterized in that, Step S6 further includes: Step S61: Select a cutoff energy of 400 eV and use a 30 × 30 × 30 refined k-point grid based on the Monkhorst-Pack method; solve the electron Boltzmann transport equation using the BoltzTraP program to obtain the electrical transport physical parameters, wherein the physical parameters include the Seebeck coefficient (S), the ratio of electrical conductivity to relaxation time (σ / τ), and the ratio of electronic thermal conductivity to relaxation time (κ0 / τ); Step S62: Using the QUANTUM ESPRESSO (QE) + Electron-Phonon Wannier (EPW) program, the relaxation time is calculated via electro-acoustic coupling. During the calculation, the cutoff energy, energy convergence criterion, k-point grid, and q-point grid are set. The hole relaxation time and electron relaxation time are calculated by analyzing the corrections to single-phonon scattering and the Fermi-Dirac distribution function. Step S63: Calculate the electrical conductivity σ, power factor PF, and electronic thermal conductivity κ. e Among them, electronic thermal conductivity κ e The calculation formula is ; Step S64: Obtain the phonon dispersion relation of the material using the supercell method; calculate the second-order and third-order force constants using a 3 × 3 × 3 supercell structure model; solve the phonon Boltzmann transport equation using ShengBTE code to calculate the lattice thermal conductivity κ of the material. L ; Verify materials with low thermal conductivity by screening based on Pugh's ratio and phonon frequency; Step S65, according to the formula Calculate the ZT value of the material in the temperature range of 300 K - 900 K.

8. The prediction method for high-performance flexible thermoelectric materials according to claim 7, characterized in that, In step S62, the formula for calculating the hole relaxation time is: in, , where is the Fermi-Dirac distribution function at the valence band peak; Let (h,k) be the energy of the quantum state (h,k). Boltzmann constant; T is temperature; The formula for calculating the electronic relaxation time is as follows: in, , is the Fermi-Dirac distribution function with the conduction band bottom; and This is the Fermi level calculated for holes and electrons in the EPW packet.

9. A predictive device for high-performance flexible thermoelectric materials, characterized in that, The prediction method for high-performance flexible thermoelectric materials according to any one of claims 1-8 includes: The cell structure optimization module is used to perform two optimization calculations on the initial crystal structure of the material to obtain the optimized cell structure; the first is a coarse-precision optimization calculation, and the second is a high-precision optimization calculation. The self-consistent calculation and bandgap screening module is used to perform self-consistent calculations on the optimized cell structure, obtain the charge density and total energy of the material through sufficient structural relaxation, and screen out semiconductor materials with band gaps in a preset bandgap through bandgap calculations. The stability assessment module is used to assess the mechanical stability, thermodynamic stability, and formation enthalpy of the semiconductor material using first-principles calculations to obtain a stable material. The ductility testing module is used to perform ductility testing on the stable material using first principles to screen out materials with high ductility. The low-frequency phonon density of states screening module is used to calculate the phonon spectrum of the high-ductility material to obtain the phonon density of states; and to screen materials whose low-frequency phonon density of states frequency is less than a preset frequency to obtain low-frequency high-ductility materials. The thermoelectric performance calculation module is used to calculate the electrical and thermal transport properties of the low-frequency, high-ductility material using first-principles calculations to obtain the ZT value of the material.

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