A first-principle screening method for flexible perovskite thermoelectric materials

Abstract

The application relates to the field of design and development of new materials, and discloses a first-principle screening method for flexible perovskite thermoelectric materials, which is based on first-principle calculation of the density functional theory and aims at improving the efficiency of discovering new materials; the screening method comprises the following steps: (1) obtaining an initial crystal structure; (2) performing magnetic testing on the material by using first-principle calculation; (3) performing sufficient structural relaxation on the material without magnetism, performing self-consistent calculation after convergence, then performing electronic structure calculation, and screening the material with a band gap; (4) performing mechanical stability judgment on the material with the band gap by using first-principle calculation, and screening the stable material; (5) performing ductility testing on the material with the band gap and the mechanical stability by using first-principle calculation, and screening the material with the ductility; and (6) performing electric transport calculation and thermal transport calculation on the material with high ductility by using first-principle calculation, and obtaining the figure-of-merit (ZT) value of the material.

Description

Technical Field

[0001] This invention relates to the field of new material design and development, specifically to a first-principles screening method for flexible perovskite thermoelectric materials. Background Technology

[0002] The limited use of fossil fuels has had a negative impact on the environment and exacerbated climate change. Therefore, achieving energy decarbonization and diversification has become an urgent global challenge, with renewable energy sources such as wind, solar, geothermal, and bioenergy playing an increasingly important role in meeting growing energy demands.

[0003] Thermoelectric materials are a new type of energy conversion material with clean energy properties, capable of directly converting heat energy into electrical energy for power generation or refrigeration. Thermoelectric materials have significant application value in power generation and waste heat recovery, helping to improve energy utilization efficiency and achieve effective energy conservation. Furthermore, thermoelectric engines do not require moving mechanical parts, offering advantages such as small size, light weight, no noise, long lifespan, and no pollution. Thermoelectric performance is typically expressed using the dimensionless thermoelectric figure of merit ZT. ,in σ is the Seebeck coefficient, and σ is the conductivity. 2 σ This is called the power factor. T Let κ be the absolute temperature and κ be the thermal conductivity, derived from the electronic thermal conductivity κ. e and lattice thermal conductivity κ L Common composition: κ=κ e +κ L .

[0004] The elastic modulus of thermoelectric materials generally ranges from tens of GPa to as high as 200 GPa, exhibiting characteristics similar to aluminum alloys near 70 GPa and steel near 200 GPa. Generally, rigid inorganic thermoelectric materials have a higher Young's modulus and are less easily broken, while flexible inorganic thermoelectric materials have a lower Young's modulus and better plasticity. Compared to bulk thermoelectric materials, flexible thermoelectric materials possess superior processability and plasticity. Flexible thermoelectric materials include conductive polymers, organic / inorganic hybrids, and inorganic compounds; however, inorganic flexible thermoelectric materials are still under development. Flexible thermoelectric materials offer new research directions for future wearable devices and sustainable energy fields.

[0005] The general chemical formula of perovskite materials is ABX3, where A and B are two cations and X is an anion. This structure consists of a shared-vertex octahedral BX6 framework. The chemical structure can be controlled by substituting the A, B, and X sites. The diversity of perovskite structure and chemical composition provides convenience for doping modification and exploring new materials. Perovskite materials have many applications in optoelectronics, catalysis, magnetism, thermoelectrics, dielectrics, and superconductivity. Currently, research on chalcogenide perovskite materials mainly focuses on their structural and electronic structures. However, in recent years, the applications of chalcogenide perovskite materials in different fields have gradually increased, such as in optoelectronics, with materials like CaZrSe3, SrZrS3, BaZrSe3, BaZrS3, and BaHfSe3. The discovery of these chalcogenide perovskite materials further enriches the application potential of perovskite materials in the thermoelectric field, providing valuable references for developing new, environmentally friendly, and high-performance thermoelectric materials. Flexible perovskite thermoelectric materials have broad potential in thermoelectric applications, but selecting the best material remains a challenge. However, traditional experimental screening methods are time-consuming and costly, so an efficient computational method is needed to identify potential candidate materials. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a first-principles screening method for flexible perovskite thermoelectric materials.

[0007] To rapidly obtain flexible perovskite thermoelectric materials, the technical solution adopted in this invention is as follows:

[0008] A first-principles screening method for flexible perovskite thermoelectric materials, the method comprising the following steps:

[0009] S1: Obtain the crystal structure of the candidate material. Obtain the crystal structure of the candidate material with an atomic ratio of A:B:X=1:1:3 from the MatHub-3d database.

[0010] S2: Material magnetic test. The magnetic properties of the material are tested using first-principles calculations. The parameter ISPIN=2 is added to INCAR. If the magnetic moment of the material is 0, it means that it is non-magnetic.

[0011] S3: Screening for bandgap materials. Perform sufficient structural relaxation on non-magnetic materials, perform self-consistent calculations after convergence, and then perform electronic structure calculations to screen out materials with bandgap.

[0012] S4: Determine the mechanical stability of materials. Use first-principles calculations to determine the mechanical stability of materials with band gaps and screen for stable materials.

[0013] S5: Test the ductility of materials. Utilize first-principles calculations to test the ductility of materials with band gaps and mechanical stability, and screen for materials with high ductility.

[0014] S6: Obtain the ZT value of the material. Use first-principles calculations to perform electrical and thermal transport calculations on the highly ductile material to obtain the figure-of-merit (ZT) value of the material.

[0015] First-principles calculations refer to calculations where, apart from telling the program the atoms used and their positions, there are no other experimental, empirical, or semi-empirical parameters, and they have excellent portability. As a basis for evaluating things, first-principles calculations and empirical parameters are two extremes; first-principles calculations are conclusions derived from certain rigid rules or deductions, while empirical parameters are regular data derived from a large number of examples, and this data can come from first-principles calculations (called theoretical statistical data).

[0016] Preferably, in step S1, the initial crystal structure is determined by searching data from an existing materials database platform, where atoms A and B have different charged cations, for example, A 1+ B 5+ X3, A 2+ B 4+ X3 and A 3+ B 3+ X3. Generally, atom A is larger than atom B. Based on the ionic radius, the atom with the larger radius will be designated as the A position, and the atom with the smaller radius will be designated as the B position.

[0017] Preferably, in step S2, only non-magnetic materials are retained for subsequent first-principles calculations.

[0018] Preferably, in step S3, the bandgap screening condition is greater than 0.1 eV, and the first-principles calculation uses VASP (Vienna) ab initio The Simulation Package software was used, employing Projected Argumented Waves (PAW) to process the electronic wavefunction. The electronic structure calculation used the mBJ (modified Becke-Johnson) + U method, where U is the Hubbard-U correction. The plane wave cutoff energy was set to 520 eV, and the energy convergence criterion was 10 eV. -4 eV.

[0019] Preferably, in step S4, the mechanical property calculation for the mechanical stability assessment adopts PBE-GGA (Performance-Based Graphology-Geometry). Burke The Ernzerhof-Generalized Gradient Approximation (ERNZH-Generalized Gradient Approximation) exchange-correlated functional has a plane wave cutoff energy of 700 eV and an energy convergence criterion of 5 × 10⁻⁶ eV. -6 eV, mechanical stability was determined using the Born-Huang criterion, and the stress-strain relationship matrix of the crystal was obtained using the EPAC (Elastic Property Automated Calculation) program.

[0020] Preferably, in step S5, the determination of whether a material is ductile or brittle can be expressed by the semi-empirical formula Pugh's ratio = G / B, where G is the shear modulus and B is the bulk modulus. When G / B < 0.571, the material has better ductility; conversely, it has better brittleness. Materials with a Pugh's ratio less than 0.571 are screened. The shear modulus and bulk modulus are calculated using the EPAC program, and the Pugh's ratio is obtained using the cij2kl-pughsratio program.

[0021] Preferably, in step S6, based on the calculation results of steps S3, S4, and S5, the TransOpt program is called to perform electrical transport calculations. The deformation potential uses the first energy band as a reference value, the Young's modulus is calculated using the EPAC program at a temperature of 300 K, the mBJ + U method is used, the plane wave cutoff energy is set to 520 eV, and the energy convergence criterion is 10 eV. -4 eV, the high-symmetry K-points in the Brillouin zone are set as 240 / a+1, 240 / b+1, and 240 / c+1, where a, b, and c are lattice constants, yielding the power factor PF and electronic thermal conductivity κ. e .

[0022] Preferably, in step S6, the lattice thermal conductivity is calculated using the Slack model, and the lattice thermal conductivity κ at a material temperature of 300 K is obtained using the cij2kl-pughsratio program. L .

[0023] Preferably, in step S6, according to the formula The ZT value of the material is obtained, where T is 300 K.

[0024] The method of this invention has the following advantages: it provides a calculation method for screening flexible perovskite semiconductor materials with high thermoelectric properties using VASP software. This invention can automate the calculation, offering advantages such as high speed and accurate results, and can provide theoretical guidance for novel flexible perovskite semiconductor materials with high thermoelectric properties. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0026] Figure 2 The atomic radii and band gaps of perovskite materials A and B are given.

[0027] Figure 3 This represents the Pugh's ratio of the perovskite material.

[0028] Figure 4 The lattice thermal conductivity of perovskite materials at a temperature of 300 K.

[0029] Figure 5 The power factor of the perovskite material at 300 K.

[0030] Figure 6 ZT value is the ZT value of the perovskite material at 300 K. Detailed Implementation

[0031] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that, in this specific embodiment, the software calculation part is based on density functional theory and uses the VASP program, which is widely used in the industry, to calculate the data in each step of the present invention.

[0033] Example:

[0034] Step 1: Select materials from the MATLAB-3d database with an atomic ratio of A:B:X = 1:1:3 and an atomic number of less than 40, where X represents S, Se, and Te respectively. There are a total of 176 initial crystal structures, 32 space groups, and six crystal systems: triclinic, monoclinic, orthorhombic, tetragonal, hexagonal, and cubic.

[0035] Step 2: Use first-principles calculations to test the magnetic properties of the material. Add the parameter ISPIN=2 to INCAR. If the magnetic moment of the material is 0, it means that it is non-magnetic.

[0036] Step 3: Perform sufficient structural relaxation on the non-magnetic material, and after convergence, perform self-consistent calculations, followed by electronic structure calculations. The plane wave cutoff energy is set to 520 eV, and the energy convergence criterion is 10 eV. -4 eV.

[0037] Step 4: The electronic structure calculation uses the mBJ (modified Becke-Johnson) + U method, where U is the Hubbard-U correction. The plane wave cutoff energy is set to 520 eV, and the energy convergence criterion is 10 eV. -4 eV. Materials with band gaps greater than 0.1 eV were selected and their mechanical stability was assessed. A total of 52 materials were evaluated, and their mechanical properties were calculated using PBE-GGA (Perdewk). Burke The Ernzerhof-Generalized Gradient Approximation (ERNZH-Generalized Gradient Approximation) exchange-correlated functional has a plane wave cutoff energy of 700 eV and an energy convergence criterion of 5 × 10⁻⁶ eV. -6 eV, mechanical stability was determined using the Born-Huang criterion, and the stress-strain relationship matrix of the crystal was obtained using the EPAC (Elastic Property Automated Calculation) software package.

[0038] Step 5: The ductility of the 52 materials was tested, and materials with high ductility were selected. 30 materials were found to meet the semi-empirical formula Pugh's ratio = G / B < 0.571, where G is the shear modulus and B is the bulk modulus. The shear modulus and bulk modulus were calculated using the EPAC software package, and the Pugh's ratio was obtained using the cij2kl-pughsratio program.

[0039] Step 6: Perform first-principles calculations on the electrical transport of the above 30 materials at 300 K using the TransOpt program. The deformation potential is calculated using the first band as a reference value. Young's modulus is calculated using the EPAC software package at 300 K, employing the mBJ + U method. The plane wave cutoff energy is set to 520 eV, and the energy convergence criterion is 10 eV. -4 eV, the high-symmetry K-points in the Brillouin zone are set as 240 / a+1, 240 / b+1, and 240 / c+1, where a, b, and c are lattice constants, yielding the power factor PF and electronic thermal conductivity κ. e .

[0040] (1) Thermal transport calculations were performed on the above 30 materials. The Slack model was used to calculate the lattice thermal conductivity, and the lattice thermal conductivity κ at a temperature of 300 K was obtained using the cij2kl-pughsratio program. L .

[0041] (2) The above power factor PF and electronic thermal conductivity κ e , lattice thermal conductivity κ LSubstituting the temperature T=300 K into the formula The ZT value of the material is obtained.

[0042] Through first-principles calculations and automated software computation, magnetic properties are determined, structural relaxation is assessed, electronic structure is calculated, ductility is determined, and the lattice thermal conductivity κ of the material is obtained. L The algorithm can quickly identify the power factor and ZT value of materials, and has the advantages of fast speed and accurate calculation results. It provides theoretical guidance for new flexible perovskite semiconductor materials with high thermoelectric performance, and realizes the ability to quickly identify the performance of materials. Compared with traditional algorithms, it is more efficient.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A first-principles screening method for flexible perovskite thermoelectric materials, characterized in that, The method includes the following steps: S1: Obtain the crystal structure of the candidate material. Obtain the crystal structure of the candidate material with an atomic ratio of A:B:X=1:1:3 from the MATLAB-3d database; where X represents S, Se and Te respectively. S2: Material magnetic test. The magnetic properties of the material are tested using first-principles calculations. The parameter ISPIN=2 is added to INCAR. If the magnetic moment of the material is 0, it means that it is non-magnetic. S3: Screening for bandgap materials. Perform sufficient structural relaxation on non-magnetic materials, perform self-consistent calculations after convergence, and then perform electronic structure calculations to screen out materials with bandgap. S4: Determine the mechanical stability of materials. Use first-principles calculations to determine the mechanical stability of materials with band gaps and screen for stable materials. S5: Test the ductility of materials. Utilize first-principles calculations to test the ductility of materials with band gaps and mechanical stability, and screen for materials with high ductility. S6: Obtain the ZT value of the material. Use first-principles calculations to perform electrical and thermal transport calculations on the highly ductile material to obtain the ZT value of the material. In step S2, only non-magnetic materials are retained for subsequent first-principles calculations; In step S5, the semi-empirical formula Pugh's ratio = G / B is used to determine whether a material is ductile or brittle, where G is the shear modulus and B is the bulk modulus. Materials with a Pugh's ratio less than 0.571 are selected. The shear modulus and bulk modulus are calculated using the EPAC program, and the Pugh's ratio is obtained using the cij2kl-pughsratio program. In step S6, based on the calculation results of steps S3, S4, and S5, the TransOpt program is called to perform electric transport calculations. The deformation potential uses the first energy band as a reference value. The Young's modulus is calculated using the EPAC program at a temperature of 300 K using the mBJ + U method. The plane wave cutoff energy is set to 520 eV, the energy convergence criterion is 10⁻⁴ eV, and the high symmetry K points in the Brillouin zone are set to 240 / a+1, 240 / b+1, and 240 / c+1, where a, b, and c are lattice constants. The power factor PF and electronic thermal conductivity κe are obtained. In step S6, the lattice thermal conductivity is calculated using the Slack model, and the lattice thermal conductivity κ at a material temperature of 300 K is obtained using the cij2kl-pughsratio program. L ; In step S6, according to the formula The ZT value of the material is obtained, where T is 300 K.

2. The first-principles screening method for flexible perovskite thermoelectric materials as described in claim 1, characterized in that, In step S1, the initial crystal structure is determined by searching data from an existing materials database platform. Atoms A and B have different charged cations, including A 1+ B 5+ X3, A 2+ B 4+ X3 and A 3+ B 3+ X3; where atom A is larger than atom B. Based on the ionic radius, the atom with the larger radius will be designated as position A, and the atom with the smaller radius will be designated as position B.

3. The first-principles screening method for flexible perovskite thermoelectric materials as described in claim 1, characterized in that, In step S3, the bandgap screening condition is greater than 0.1 eV. First-principles calculations are performed using VASP software, and the electronic wavefunction is processed using PAW in projected fused wavelet analysis. The electronic structure calculation uses the mBJ + U method, where U is the Hubbard-U correction. The plane wave cutoff energy is set to 520 eV, and the energy convergence criterion is 10 eV. -4 eV.

4. The first-principles screening method for flexible perovskite thermoelectric materials as described in claim 1, characterized in that, In step S4, the mechanical property calculation for mechanical stability assessment uses the PBE-GGA exchange-correlated functional, with a plane wave cutoff energy of 700 eV and an energy convergence criterion set at 5 × 10⁻⁶ eV. -6 eV, mechanical stability is determined using the Born-Huang criterion, and the stress-strain relationship matrix of the crystal is obtained using the EPAC program.

Images