Method for screening two-dimensional p-421mxy2 material with high piezoelectric strain coefficient and application

Abstract

The present application belongs to the technical field of material quantitative design, and particularly relates to a method for screening two-dimensional P21m XY2 materials with high piezoelectric strain coefficient and application. The method takes two-dimensional pentagonal P21m XY2 with space group number 113 and primitive cell Z=2 as a prototype, selects group IA-VIIA main group elements, generates candidate phases through element substitution, sequentially completes structure, elasticity, dynamics and thermodynamics multi-level stability screening relying on the first principle high-throughput workflow, excludes metal and ferromagnetic phases based on the relationship between valence electron count and Y2 dimer orbital occupation, and retains 10, 12 and 14 valence electron semiconductor phases; the piezoelectric related parameters are calculated by using the density functional perturbation theory, and the target material is screened according to the out-of-plane piezoelectric strain coefficient threshold value, and the out-of-plane piezoelectric strain coefficient of the target material is 18-60 pm / V. The method clarifies the structure-effect relationship, and the screened material can be applied to flexible electronics and shear mode piezoelectric devices.

Description

Technical Field

[0001] This invention belongs to the field of quantitative material design technology, specifically relating to a two-dimensional P-type method for screening high-voltage electrical strain coefficients. 21m XY2 material methods and applications. Background Technology

[0002] Since the successful exfoliation of graphene, a wealth of research has been dedicated to exploring the synthesis and applications of two-dimensional (2D) materials. To date, a variety of structural prototypes of 2D materials have been discovered, including honeycomb lattices (e.g., graphene and h-BN), Xenes, transition metal dichalcogenides, MXenes, MBenes, perovskites, Janus structures, and heterostructures. With the rapid development of computational materials science and the continuous improvement of computing power, researchers have utilized various algorithms and methods to predict a large number of novel 2D materials, such as evolutionary algorithms, particle swarm optimization, group theory and graph theory methods, as well as widely adopted element substitution strategies. These theoretical studies have not only significantly expanded the family of 2D materials but also provided essential guidance for experimental synthesis and application development, effectively bridging the gap between computational predictions and experimental realization.

[0003] Among various two-dimensional materials, two-dimensional pentagonal lattices, composed entirely or partially of pentagons, have attracted considerable attention due to their unique structure and physical properties. In the two-dimensional limit, such pentagonal lattices have been theoretically predicted in elemental, binary, and ternary systems with different space groups, such as P4bm SnN2, P4 / mbm HfC, P12m SiN2, NiN2, and RuS4. Experimental progress has also confirmed the syntheticability of these two-dimensional pentagonal materials, successfully preparing PdSe2, PdS2, NiN2, and PdPSe. In addition to structural diversity, two-dimensional pentagonal lattices also exhibit a variety of interesting physical phenomena, such as epitaxial behavior, ferroelectricity, ferromagnetism, highly efficient electrocatalytic nitrogen reduction activity, and second harmonic generation, highlighting their application potential in flexible electronics, spintronics, optoelectronics, and catalysis.

[0004] The immense diversity of structural prototypes and stoichiometry in two-dimensional pentagonal lattices makes it impossible to comprehensively investigate all possible configurations in a single study. Among the numerous structural prototypes and stoichiometry that may exist in two-dimensional pentagonal lattices, we focus here on those using P... The two-dimensional pentagonal phase of the prototype 21m XY2 (space group number 113, unit cell containing Z=2 chemical formula units). Since the proposal of two-dimensional P in 2015... Since 21m CC2 (pentagonal graphene), there have been approximately 36 crystallizations of two-dimensional P Compounds of the 21mXY2 prototype—including borides (e.g., SB2, SeB2, TeB2), carbides (e.g., AlC2, GeC2), nitrides (e.g., SiN2, AlN2), and sulfides (e.g., BeS2)—have been theoretically reported. These known two-dimensional pentagonal P... The 21mXY2 phase has been found to exhibit very different electronic properties, displaying semiconductor, metallic, and even ferromagnetic behavior. However, the fundamental physical and chemical mechanisms determining these properties remain unclear to date. Furthermore, previously determined structures do not reveal the elemental compositional distribution pattern of this chemical formula, the chemical space accessible through elemental substitution remains largely unexplored, and the piezoelectric properties exhibited by this type of material have not been thoroughly investigated. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method and application for screening two-dimensional P421mXY2 materials with high-voltage strain coefficients. It reveals a clear correlation between the number of valence electrons, dimer bonding configuration, and the resulting electronic structure. This systematic exploration deepens the understanding of structure-property relationships in two-dimensional pentagonal lattices and provides a practical design guide for designing multifunctional two-dimensional materials with tunable properties.

[0006] The technical solution of this invention is as follows:

[0007] In a first aspect, the present invention provides a two-dimensional P-type method for screening high-voltage electrical strain coefficients. The 21m XY2 material method includes the following steps:

[0008] S1, a two-dimensional pentagon P with space group number 113 and unit cell Z=2. The 21m XY2 structure serves as the prototype, where X and Y are selected from main group elements of groups IA-VIIA. Multiple candidate materials are generated through element substitution.

[0009] S2. Construct a first-principles high-throughput computational workflow to sequentially perform structural optimization, elastic stability screening, and dynamic stability screening on candidate materials, thereby obtaining stable candidate two-dimensional P-materials. 21m XY2 material set;

[0010] S3. Based on valence electron counting and Y2 dimer orbital occupancy relationship, the stable candidate two-dimensional P Preliminary screening was conducted on the 21m XY2 material set, and semiconductor phase materials with valence electrons of 10, 12, and 14 were obtained.

[0011] S4. Using first-principles density functional perturbation theory, the shear elastic constant and piezoelectric stress coefficient of semiconductor phase materials are calculated, and then the out-of-plane piezoelectric strain coefficient is obtained.

[0012] S5. Based on the magnitude of the out-of-plane piezoelectric strain coefficient, a two-dimensional P with a high piezoelectric strain coefficient is obtained. Target material 21mXY2.

[0013] Further optimization, in step S2, structural optimization maintains P With 21m symmetry, candidate materials that could not maintain a two-dimensional X2Y3 pentagonal framework after optimization were eliminated. Stable candidate two-dimensional P-shaped materials were evaluated by elastic tensor calculation. The elastic stability of the 21m XY2 material assembly was determined by the absence of imaginary frequencies in the phonon dispersion curve.

[0014] Further optimization includes step S2, which further includes thermodynamic stability verification: calculating the two-dimensional unit cell P based on the cohesive energy calculation formula. The cohesive energy of 21m XY2 was used to screen candidate materials with cohesive energy in the range of 2.3 to 5.4 eV / atom.

[0015] Further optimization is achieved in step S3, where the valence electron count and the Y2 dimer orbital occupancy relationship are as follows: each XY2 chemical formula corresponds to one of the following valence electron numbers: 10, 11, 12, 13, or 14. Specifically, two-dimensional P-type dimers with 10, 12, or 14 valence electrons... 21mXY2 materials exhibit semiconductor conductivity; while two-dimensional P materials with 11 and 13 valence electrons... The 21m XY2 material exhibits metallic or ferromagnetic behavior, thus it is excluded from the piezoelectric primary screening set.

[0016] Further optimization involves step S4, where first-principles calculations are performed within the framework of density functional theory using the Vienna Ab initio simulation package (VASP), and density functional perturbation theory is employed to calculate the shear elastic constant C of the semiconductor material. 66 piezoelectric stress coefficient e 36 The piezoelectric strain coefficient d is calculated using the following formula. 36 :

[0017] .

[0018] Further optimization involves using a high-voltage strain coefficient of 18-60 pm / V in step S5, which is then selected by screening P. 21mSnBi2、P 21m GeBi2, P 21m TeGe2 and P At least one target material in 21m PbBi2.

[0019] Further optimization also includes conducting piezoelectric origin analysis on the screened target materials: based on the crystal orbital method occupied by Y2 dimer orbitals, the physical mechanism of the high out-of-plane piezoelectric response of the target materials is analyzed from the perspectives of piezoelectric stress tensor, shear modulus, atomic polarizability and stereochemically active lone pair electrons.

[0020] Secondly, the present invention provides a two-dimensional P-type method for screening high-voltage electrical strain coefficients. Two-dimensional P obtained from any of the 21m XY2 material methods 21m XY2 piezoelectric material.

[0021] Thirdly, the present invention provides a two-dimensional P Applications of 21m XY2 material in flexible electronics and shear-mode piezoelectric devices.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention establishes a high-throughput screening method for two-dimensional P-type high-voltage strain coefficients based on the intrinsic correlation between valence electron counting and Y2 dimer orbital occupancy. The method for developing 21m XY2 materials, compared to traditional trial-and-error theoretical prediction methods, can rapidly narrow down the range of candidate materials, reduce a large number of meaningless first-principles calculations, and improve the efficiency of discovering novel two-dimensional piezoelectric materials. The two-dimensional materials such as SnBi2, GeBi2, TeGe2, and PbBi2 ​​screened by this invention possess high out-of-plane piezoelectric strain coefficients of 18-60 pm / V, significantly higher than most previously reported pentagonal two-dimensional piezoelectric materials. These materials achieve excellent shear-mode piezoelectric responses through the synergistic effect of low shear modulus, large piezoelectric stress tensor, and stereochemically active lone pair electrons, making them suitable for the application requirements of ultrathin two-dimensional devices. This invention clarifies the structure-property relationship between valence electrons, dimer bonding, and piezoelectric properties in these two-dimensional pentagonal materials, providing theoretical guidance for the directional design of two-dimensional materials with tunable piezoelectric properties. The high-voltage two-dimensional materials obtained through screening can be applied to flexible electronics and shear-mode piezoelectric devices, and have promising applications in wearable devices, soft robots, surface acoustic wave devices, and other fields. At the same time, the determined van der Waals epitaxial preparation scheme reduces the stringent requirements for lattice matching in experimental synthesis, which is conducive to promoting the subsequent experimental preparation and device application of this type of two-dimensional piezoelectric material. Attached Figure Description

[0024] Figure 1 P is a two-dimensional pentagon Schematic diagram of 21m XY2 (Z=2) material, where (a) is a two-dimensional P (a) Crystal structure of 21m XY2 material; (b) is a two-dimensional P Flowchart of the structural screening process for 21m XY2 materials;

[0025] Figure 2 For two-dimensional P A schematic diagram of the structure-electronic properties of 21m XY2 material, where (a) is the orbital diagram of the H2YYH2 unit (10 valence electrons) and (b) is the Lewis structure diagram of the X2YYX2 species with 10-14 valence electrons;

[0026] Figure 3 Five two-dimensional P-type functionals calculated using PBE functionals The coefficient curve of 21m XY2 material, where (a) is the elastic constant C. 66 (N / m), (b) is the piezoelectric stress coefficient e 36 (10-10 C / m), (c) is the piezoelectric strain coefficient d 36 (pm / V). Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are...

[0028] Examples are provided to facilitate understanding of the invention and are not intended to limit it in any way.

[0029] A two-dimensional P-type method for screening high-voltage electric strain coefficients The 21m XY2 material method includes the following steps:

[0030] S1, a two-dimensional pentagon P with space group number 113 and unit cell Z=2. The 21m XY2 structure is the prototype, such as Figure 1 (a)

[0031] As shown, the two-dimensional prototype structure is composed of tilted X2Y3 pentagons. The structure contains Y2 dimer structural units. X atoms are tetrahedral coordinated and Y atoms are trigonal pyramidal coordinated. In order to achieve thermodynamic stability, the two-dimensional pentagonal framework has an inherent non-planar configuration with out-of-plane warping.

[0032] X and Y are selected from the main group elements of groups IA-VIIA, and the selection range includes H-Cs, Be-Ba, B-Tl, C-Pb, N-Bi, O-Te, and FI. A total of 1156 candidate materials were generated through the element substitution strategy.

[0033] S2, such as Figure 1 As shown in (b), a first-principles high-throughput computational workflow is constructed. All first-principles calculations are based on the density functional theory framework, using the Vienna Ab initio Simulation Package (VASP), employing the all-electron projected fused wave (PAW) method, and the PBE functional under the generalized gradient approximation. The kinetic energy cutoff energy of the plane wave is set to 600 eV, and a spacing of [missing information] is used. The Brillouin zone is sampled using a Monkhorst-Pack k-point grid; the convergence criteria are set as follows: the convergence of cell energy and cell force is 1×10⁻⁶. -5 Within eV and 0.01 eV / A; the phonon dispersion curves were calculated using phonopy software.

[0034] First, structural optimization was performed on 1156 candidate materials, maintaining P throughout the calculation process. After optimizing the symmetry of the 21m space group, candidate materials that could not maintain the X2Y3 pentagonal skeleton were removed, leaving 582 candidate materials.

[0035] Next, elastic stability screening was carried out: for 582 candidate materials, the elastic tensor was calculated by applying six finite lattice distortions, and the elastic constants were obtained from the stress-strain relationship. Based on the elastic stability data, 399 candidate materials with elastic stability were obtained.

[0036] Then, dynamic stability screening was carried out: phonon dispersion curves of 399 candidate materials were calculated, and structures exhibiting imaginary frequencies or dynamic instability were eliminated.

[0037] Finally, thermodynamic stability was verified using the cohesive energy calculation formula:

[0038] ,

[0039] Where E(X) and E(Y) are the energies of isolated X atoms and isolated Y atoms, respectively, and E(XY2) is the total energy of a two-dimensional XY2 unit cell with Z=2. The cohesive energy of candidate materials is calculated, and candidate materials with cohesive energies between 2.3 and 5.4 eV / atom are selected.

[0040] In addition, AIMD molecular dynamics simulations were conducted at 300 K to verify thermal stability, ultimately yielding stable candidate two-dimensional P 21m XY2 material set.

[0041] This embodiment, through multi-level screening, verified 37 previously unreported stable new two-dimensional P-types. For 21m XY2 materials, since there is no corresponding van der Waals layered phase analogue for this type of new material, the experimental preparation can be carried out using van der Waals epitaxial growth process. Unlike traditional epitaxy, van der Waals epitaxy relaxes the strict lattice matching requirements due to the weaker van der Waals interactions at the interface, allowing high-quality growth on various substrates. In this embodiment, the substrate can be mica, SiO2 / Si, or graphene / SiC.

[0042] S3. To rationalize the structure-valence electron (VE) correlation, an orbital-based analysis was performed on the X2YYX2 structural unit, modeling it as H2Y-YH2 (10 valence electrons, with C... 2v Symmetry). Figure 2 As shown in (a), the interaction between the two bent molecular H2Y segments generates four key orbitals: bonding σ orbitals, antibonding σ orbitals, and antibonding σ orbitals. orbital, nonbonded n ns orbit and phase reversal track. Figure 2 (b) also depicts Lewis structures of X2YYX2 species with different VEs.

[0043] All stable candidate phases were categorized according to the total number of valence electrons in each XY2 chemical unit. The correspondence between the number of valence electrons and the conductivity of the material is shown in Table 1.

[0044] Table 1 Two-dimensional P Correlation between valence electrons and electrical conductivity in the 21m XY2 chemical formula

[0045]

[0046] Based on valence electron counting and Y2 dimer orbital occupancy relationship, stable candidate two-dimensional P Initial screening was conducted on the 21m XY2 material set: semiconductor phase materials with 10, 12, or 14 valence electrons per XY2 chemical formula unit were selected and retained for further calculations. Phases with 11 or 13 valence electrons were excluded because their highest occupied orbitals contain unpaired electrons, exhibiting metallic or ferromagnetic properties, and are unsuitable for piezoelectric applications.

[0047] Combination Figure 2 (a) Figure 2 (b) Further explanation of track filling:

[0048] 10-valent electron (10-VE) system: corresponds to a fully filled bonding σ orbital, which forms the highest occupied molecular orbital (HOMO), while the empty n orbital... s The orbital is the lowest unoccupied molecular orbital (LUMO), such as... Figure 2 As shown in (a), this electronic configuration produces a fairly large HOMO-LUMO gap (1g-1gp), explaining the two-dimensional 10-VE P The semiconductor behavior of the 21m XY2 phase is as observed in previously reported IV-III2 materials (e.g., CB2 and CGa2). In two-dimensional 10-VE P In the 21m XY2 phase, the fully occupied σ bonding orbitals generate a YY bond order of ~1, which is consistent with the calculated Manz bond order value (0.61-1.12).

[0049] 11-valent electron system: possesses σ 2 n π Electronic states, containing an unpaired electron as a HOMO level, explain the metallic or magnetic behavior observed in the two-dimensional extended XY2 systems (such as the III-IV2 (e.g., BC2) and V-III2 (e.g., PB2) phases), C2 3- The dimer exhibits short C-C bonds (1.28–1.37 Å, Manz order 1.56–2.53), while in two-dimensional P Isoelectronic B2 in 21m PB2, AsB2 and SbB2 5- The unit cell retains partially filled bonding orbitals, consistent with the presence of unpaired electrons.

[0050] 12-valent electron systems: can employ low-spin singlet states (σ... 2 n π 2 ) or high-spin triplet state ( ), where n π and The energy separation between orbitals is strongly dependent on composition and geometry. Increasing the electronegativity of X preferentially stabilizes the singlet state through negative hyperconjugation (σ_Y-Y → σ_Y–X), which aligns with the predicted two-dimensional P... The stability of the 21m XY2 series remains consistent. Pyramidification at Y further modulates electron preference: small angles (≈0°) enhance π-type interactions and favor singlet states, while larger angles introduce more sp... 3 Characterized and stable triplet state. The Lewis structure of H₂X-XH₂ with 12 valence electrons is as follows... Figure 2 As shown in (b). In the singlet state, the in-phase n π Complete occupancy of an orbital corresponds to a formal bond order of 2. Representative examples include two-dimensional P... 21mSiC2, GeC2 and SnC2 phases (C2 4- (CC distance is 1.34–1.37 Å; Manz bond order is 1.83–2.12), similar behavior has been observed in VI–III2 and II–V2 compounds—for example, BeN2 and MgN2, which have N2 in form. 2- Cell (NN distance) Å; Manz bond order is 1.92–2.27). In the singlet state, the occupied n of Y2X-XY2 π Orbit and space A distinct energy gap appears between the orbitals. Consistent with this molecular orbital pattern, hybrid HSE06 calculations show that the 12-VE P orbitals are distributed across the entire two-dimensional plane. Band gaps of 0.8–3.26 eV were obtained in XC2 (X=C, Si, Ge and Sn, 1.36–3.26 eV), XB2 (X=S, Se and Te, 1.9–2.0 eV) and BeP2 (0.8 eV) of the 21 m XY2 series.

[0051] 13-valent electron system: with half-filled n π The presence of this single-occupied orbital places the Fermi level within a partially filled band as a HOMO level, resulting in metallic or magnetic behavior. Representative examples include III-V2 (BN2, BP2, AlP2) and V-IV2 (NC2, PC2) compositions.

[0052] A 14-valent electron system: This system contains three of its four orbitals that are filled, corresponding to... Configuration. This electronic structure is consistent with the local bonding picture, including a lone pair of electrons and a YY bond at each Y center (see Figure 2 In these two-dimensional systems, completely occupied nonbonded elements... The orbits form a HOMO, while the empty ones The orbitals act as LUMOs. The resulting HOMO-LUMO separation leads to semiconductor behavior in a two-dimensional 14-valence electron system (see...). Figure 1 Two-dimensional P The IV-V2 phase of 21m CN2 exmplifies this configuration, and its Lewis structure is as follows: Figure 2 As shown in (b). In two-dimensional P In 21m CN2, sp 3 The hybrid C (tetrahedral AX4E0) and N (trigonal pyramidal AX3E1) centers satisfy the octet rule, and the N-N bond distance is 1.45 Å, reflecting the expected single-bond characteristics. In the ionic system, the two-dimensional P The N2 unit in 21m CN2 can be designated as a 4-charge in form (N2 4- Isoelectronic analogues, including IV2 and V2. 4- and VI2 2 Dimers (e.g., Si2 in TeSi2) 6- Bi2 in CBi2 4- Se2 in BeSe2 2- (Also being a 14-valent electron system, this makes it possible to form IV-V2, VI-IV2, and II-VI2.)

[0053] When the number of valence electrons deviates from the 10-14 range (e.g., 9 or 15 valence electrons), the YY bond weakens significantly, and the P... The 21m XY2 prototype is difficult to maintain stably. Some phases can achieve dynamic stability by reducing space group symmetry through Peierls distortion, but these are not among the prototypes screened in this invention.

[0054] S4, Two-dimensional P 21m XY2 material belongs to D 2d According to crystal group theory, under this symmetry, the material only exhibits an out-of-plane piezoelectric response; the out-of-plane piezoelectric strain coefficient d 36 The ability to induce out-of-plane polarization by in-plane shear strain is a core evaluation parameter for shear-mode piezoelectric devices; the piezoelectric tensor includes both ionic and electronic contributions.

[0055] Using first-principles density functional perturbation theory, the shear elastic constant and piezoelectric stress coefficient of semiconductor materials are calculated, and then the out-of-plane piezoelectric strain coefficient is obtained.

[0056] The relaxation ion piezoelectric stress coefficient e of the semiconductor phase was calculated using density functional perturbation theory. 36 and shear elastic constant C 66 out-of-plane piezoelectric strain coefficient d 36 The calculation formula is as follows:

[0057] .

[0058] S5. Set the screening threshold: out-of-plane piezoelectric strain coefficient d 36 ≥18 pm / V, the calculation results of all semiconductor materials were compared and screened.

[0059] like Figure 3 As shown, most of the two-dimensional P in this embodiment The piezoelectric strain coefficient of 21m XY2 material is less than 5 pm / V; the out-of-plane piezoelectric strain coefficients d of the target two-dimensional piezoelectric materials SiBi2, SnBi2, GeBi2, TeGe2, and PbBi2 ​​obtained through screening are... 36 The piezoelectric coefficients of these materials are 8.47 pm / V, 22.62 pm / V, 29.86 pm / V, 17.96 pm / V, and 59.81 pm / V, respectively. These materials exhibit significantly higher piezoelectric coefficients than previously reported pentagonal two-dimensional piezoelectric materials such as pentagonal-graphene, pentagonal-BCN, and pentagonal-CoSeS.

[0060] This is mainly due to the large piezoelectric stress coefficient e 36 and the reduced shear elastic constant C 66 The combination of. More precisely, two-dimensional P The significant out-of-plane piezoelectric response of 21mPbBi2 ​​can be attributed to several intrinsic factors. First, in the two-dimensional P... In 21mPbBi₂, the comparable atomic polarizability between Pb and Bi results in highly polarized Pb-Bi bonds, which in turn enhances the polarization response under shear strain, thereby increasing e 36 Secondly, the large atomic radii and high atomic masses of Pb and Bi contribute to the formation of a softer shear elastic constant C. 66 Third, the stereochemically active lone pairs of electrons (6s electrons) on Bi and Pb atoms. 2 This induces local structural distortions and promotes spontaneous atomic shifts. Under shear deformation, these lone pairs of electrons can be easily reoriented or shifted, further amplifying out-of-plane polarization and affecting high-d electrons. 36 The coefficient made a significant contribution.

[0061] This embodiment also uses the HSE06 hybrid functional to calculate the bandgap of the semiconductor phase. As shown in Table 2, the HSE06 bandgap of the 410, 12, and 14 valence electron semiconductor phases is distributed in the range of 0.8-6.5 eV, covering the infrared to ultraviolet spectral range, and has the potential for optoelectronic applications. As shown in Table 3, some 11-valence and 13-valence electron phases exhibit ferromagnetic semiconductor characteristics, such as SbB2 (HSE06 bandgap 1.06 eV), AsB2 (HSE06 bandgap 1.19 eV), and LiO2 (HSE06 bandgap 2.75 eV), which can be used for spintronic devices.

[0062] Table 2. Bandgap calculation of semiconductor phases

[0063]

[0064]

[0065]

[0066] Table 3. Some 11-valent and 13-valent electron phases exhibit ferromagnetic semiconductor properties.

[0067]

[0068] The two-dimensional piezoelectric materials obtained by screening in this invention can be applied to flexible electronics and shear-mode piezoelectric devices. The materials can be used as sensing units, driving units or energy harvesting units to prepare wearable electronic devices, soft robots and tunable surface acoustic wave devices.

[0069] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A two-dimensional P-type method for screening high-voltage electrical strain coefficients 21m XY2 material method, characterized in that, Includes the following steps: S1, a two-dimensional pentagon P with space group number 113 and unit cell Z=2. The 21m XY2 structure serves as the prototype, where X and Y are selected from main group elements of groups IA-VIIA. Multiple candidate materials are generated through element substitution. S2. Construct a first-principles high-throughput computational workflow to sequentially perform structural optimization, elastic stability screening, and dynamic stability screening on candidate materials, thereby obtaining stable candidate two-dimensional P-materials. 21m XY2 material set; S3. Based on valence electron counting and Y2 dimer orbital occupancy relationship, the stable candidate two-dimensional P Preliminary screening was conducted on the 21m XY2 material set, and semiconductor phase materials with valence electrons of 10, 12, and 14 were obtained. S4. Using first-principles density functional perturbation theory, the shear elastic constant and piezoelectric stress coefficient of semiconductor phase materials are calculated, and then the out-of-plane piezoelectric strain coefficient is obtained. S5. Based on the magnitude of the out-of-plane piezoelectric strain coefficient, a two-dimensional P with a high piezoelectric strain coefficient is obtained. 21m XY2 target material.

2. The screening method according to claim 1, characterized in that, In step S2, structural optimization maintains P With 21m symmetry, candidate materials that could not maintain a two-dimensional X2Y3 pentagonal framework after optimization were eliminated. Stable candidate two-dimensional P-shaped materials were evaluated by elastic tensor calculation. The elastic stability of the 21m XY2 material assembly was determined by the absence of imaginary frequencies in the phonon dispersion curve.

3. The screening method according to claim 1, characterized in that, Step S2 also includes thermodynamic stability verification: calculating the cohesive energy of candidate materials according to the cohesive energy calculation formula, and screening candidate materials with cohesive energy in the range of 2.3 to 5.4 eV / atom.

4. The screening method according to claim 1, characterized in that, In step S3, the relationship between valence electron count and Y2 dimer orbital occupancy is as follows: each XY2 chemical formula corresponds to one of the following valence electron numbers: 10, 11, 12, 13, or 14. Specifically, two-dimensional P-type dimers with 10, 12, or 14 valence electrons... 21m XY2 materials exhibit semiconductor conductivity; while two-dimensional P materials with 11 and 13 valence electrons... The 21m XY2 material exhibits metallic or ferromagnetic behavior, thus it is excluded from the piezoelectric primary screening set.

5. The screening method according to claim 1, characterized in that, In step S4, the first-principles calculations are performed within the framework of density functional theory using the Vienna Ab initio simulation package (VASP), and the shear elastic constant C of the semiconductor material is calculated using density functional perturbation theory. 66 piezoelectric stress coefficient e 36 The piezoelectric strain coefficient d is calculated using the following formula. 36 : 。 6. The screening method according to claim 1, characterized in that, In step S5, the high-voltage strain coefficient is 18–60 pm / V, and P is selected. 21m SnBi2, P 21m GeBi2, P 21m TeGe2 and P At least one target material in 21m PbBi2.

7. The screening method according to claim 1, characterized in that, It also includes piezoelectric origin analysis of the screened target materials: based on the crystal orbital method occupied by Y2 dimer orbitals, the physical mechanism of the high out-of-plane piezoelectric response of the target materials is analyzed from the perspectives of piezoelectric stress tensor, shear modulus, atomic polarizability and stereochemically active lone pair electrons.

8. A two-dimensional P-type high-voltage strain coefficient obtained by the screening method according to any one of claims 1-7. 21mXY2 material.

9. A two-dimensional P-type method for screening high-voltage strain coefficients as described in claim 8. Applications of 21m XY2 material in flexible electronics and shear-mode piezoelectric devices.

Images