Design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance

Abstract

The invention discloses a design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance, and relates to the technical field of analog computation of new energy materials. The method comprises the following steps: constructing two novel two-dimensional material GaAs3 and InAs3 single-layer film structures; first principle calculation software VASP based on the density functional theory is adopted to carry out structure optimization on the two-dimensional material GaAs3 single-layer film and the InAs3 single-layer film, and structure models of the two-dimensional material GaAs3 single-layer film and the InAs3 single-layer film are obtained; the phonon spectrums are respectively calculated to ensure that the structure can exist stably; a non-equilibrium Green function method and a Landaauer-Buttiker theory are combined to systematically research and analyze the stability, the electron and heat transport characteristics and the thermoelectric figure of merit. The result shows that both the GaAs3 single-layer film and the InAs3 single-layer film have high thermoelectric conversion efficiency, and the thermoelectric figure of merit of p-type doping in the zigzag direction under 300K reaches 3.75 and 3.78 respectively. Compared with an experimental method, the method has the advantage of quickly obtaining a high-performance thermoelectric structure, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of simulation calculation of new energy materials, and in particular to a design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance. Background Art

[0002] Thermoelectric materials, also known as temperature difference power generation materials, are functional materials that use the movement of carriers inside semiconductor materials to directly realize the mutual conversion of thermal energy and electrical energy. They have the advantages of being clean and pollution-free. The conversion efficiency of thermoelectric devices is measured by the thermoelectric figure of merit ZT, which is related to the Seebeck coefficient, electrical conductivity and thermal conductivity of the material. If the thermoelectric figure of merit ZT is increased, the efficiency of electrical energy conversion will increase. Therefore, to achieve high efficiency in power generation, it is important to explore thermoelectric conversion materials with large Seebeck coefficient and electrical conductivity and small thermal conductivity. Increasing the Seebeck coefficient and electrical conductivity of thermoelectric conversion materials while reducing thermal conductivity can improve thermoelectric performance. However, these thermoelectric parameters are coupled and related to each other, making it difficult to regulate independently, which makes it difficult to improve the thermoelectric efficiency and makes the development cost of thermoelectric films in experiments high.

[0003] In recent years, research has found that the low-dimensional thin film of thermoelectric materials can effectively improve the thermoelectric figure of merit of the material through low-dimensional quantum localization effect and interface effect. At the same time, two-dimensional thin film materials can be independently made into thermoelectric devices as needed, and it is easier to realize miniaturized thermoelectric devices. Therefore, the research on the thin film of thermoelectric materials is one of the key topics in the current field of materials research. Summary of the invention

[0004] In view of the deficiencies in the current prior art, the present invention provides a design method for GaAs3 and InAs3 thin film materials with high thermoelectric performance, aiming to make theoretical predictions on high-performance thermoelectric structures from a theoretical perspective, thereby providing a theoretical basis and guidance for related experiments.

[0005] The technical solution adopted by the present invention to achieve the above technical effects is:

[0006] A method for designing GaAs3 and InAs3 thin film materials with high thermoelectric performance comprises the following steps:

[0007] S1. Establish the model structure of GaAs3 and InAs3 thin films, optimize the structure by using the first-principles calculation software VASP, and read the energy value in OUTCAR to obtain the most stable primitive cell structure of GaAs3 and InAs3 thin films;

[0008] S2. Calculate the phonon spectra of GaAs3 and InAs3 thin film models using the first-principles calculation software VASP combined with the Phonopy package to determine their structural stability;

[0009] S3, using the first-principles calculation software VASP to calculate the band structure and state density of GaAs3 and InAs3 films, as well as the two-dimensional projection diagram of the valence band top (VBM) and conduction band bottom (CBM) of the first Brillouin zone;

[0010] S4. Based on the results calculated in step S3, the Seebeck coefficient S, electrical conductivity σ, and electronic thermal conductivity κ of GaAs3 and InAs3 films are calculated using Nanodcal calculation software. e , lattice thermal conductivity κ l And the thermoelectric figure of merit ZT.

[0011] Preferably, in the above-mentioned method for designing GaAs3 and InAs3 thin film materials with high thermoelectric performance, in the step S1, a vacuum layer of more than 15 angstroms is added on the surface of the GaAs3 and InAs3 thin films.

[0012] Preferably, in the above-mentioned method for designing GaAs3 and InAs3 thin film materials with high thermoelectric performance, in the step S1, a vacuum layer of 20 angstroms is added on the surface of the GaAs3 and InAs3 thin films.

[0013] Preferably, in the above-mentioned design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance, the unit cell structure of the GaAs3 and InAs3 thin film surfaces along the zigzag direction and the armchair direction is selected.

[0014] Preferably, in the above-mentioned design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance, in step S1, after the model structure is established, the first-principles calculation software VASP is used to relax the atomic positions of the unit cell structure, wherein the cutoff energy is set to 500eV, the K point is set to 9×9×1, the electron convergence accuracy is 1E-8eV, and the ion convergence accuracy is

[0015] Preferably, in the above-mentioned design method of GaAs3 and InAs3 thin film materials with high thermoelectric properties, in step S3, the unit cell structure optimized in step S2 is taken as the research object, and the first-principles calculation software VASP is used to perform non-static self-consistent calculations, so as to calculate the band structure and state density of the unit cell structure.

[0016] Preferably, in the above-mentioned design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance, the non-static self-consistent calculation of the unit cell structure is divided into 9×9×1 K points.

[0017] Preferably, in the above-mentioned method for designing GaAs3 and InAs3 thin film materials with high thermoelectric performance, in step S4,

[0018] The calculation formula of Seebeck coefficient S is:

[0019] Among them, e is the electron charge, T is the absolute temperature;

[0020] The calculation formula of conductivity σ is:

[0021] σ=e 2 L0 / l, where e is the electron charge and l is the device length;

[0022] Electronic thermal conductivity κ e The calculation formula is:

[0023] Where, T is the absolute temperature and l is the length of the device;

[0024] Lattice thermal conductivity κ l The calculation formula is:

[0025] Where S is the Seebeck coefficient, h is the ratio of Planck constant to 2π, n is the nth phonon line, v n is the group velocity, ω n is the angular frequency of the lattice wave, f is the Fermi-Dirac distribution function, and T is the absolute temperature;

[0026] The calculation formula of thermoelectric figure of merit ZT is:

[0027] Where S is the Seebeck coefficient, α is the conductivity, T is the absolute temperature, κ e is the electronic thermal conductivity, κ l is the lattice thermal conductivity;

[0028] In the above formula, L0, L1 and L2 are obtained by the integral formula Where m = (0, 1, 2), h is Planck's constant, T e (ε) is the electron transmission spectrum, μ is the Fermi energy, and f is the Fermi-Dirac distribution function.

[0029] The beneficial effects of the present invention are as follows: the present invention optimizes the structure of the primitive cell of GaAs3 and InAs3 thin films by using the first principle calculation software VASP, thereby obtaining its phonon spectrum and judging its stability, and then obtains the corresponding band structure and state density by performing non-static self-consistent calculation on the primitive cell structure of GaAs3 and InAs3 thin films, and gives a two-dimensional projection of the valence band top (VBM) and conduction band bottom (CBM) in the first Brillouin zone. Based on the electronic structure, the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, lattice thermal conductivity and thermoelectric figure of merit ZT are calculated, and high-performance thermoelectric structures can be theoretically predicted from a theoretical perspective, thereby providing a theoretical basis and guidance for related experiments, saving experimental costs and improving the efficiency of thermoelectric material design. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The structural diagram of GaAs3 and InAs3 thin film primitive cells after structural optimization in the embodiment of the present invention;

[0031] Figure 2 is the phonon spectrum of the GaAs3 film in the embodiment of the present invention;

[0032] Figure 3 is the phonon spectrum of the InAs3 film in the embodiment of the present invention;

[0033] Figure 4 The energy band structure and state density diagram of the GaAs3 film along the zigzag direction in the embodiment of the present invention;

[0034] Figure 5 The energy band structure and state density diagram of the InAs3 film along the zigzag direction in the embodiment of the present invention;

[0035] Figure 6 The energy band structure and state density diagram of the GaAs3 film along the armchair direction in the embodiment of the present invention;

[0036] Figure 7 The energy band structure and state density diagram of the InAs3 film along the armchair direction in the embodiment of the present invention;

[0037] Figure 8 is the Seebeck coefficient of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention.

[0038] Fig. 9 : is the conductivity of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention.

[0039] Fig.10 : is the power factor of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention.

[0040] Fig.11 is the electron thermal conductivity of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention.

[0041] Fig.12 : is the lattice thermal conductivity of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention.

[0042] Fig.13 : It is the thermoelectric figure of merit ZT of GaAs3 and InAs3 films along the zigzag direction and armchair direction at 300K in the embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to further understand the present invention, the present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0044] The embodiment of the present invention provides a design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance, comprising the steps of:

[0045] S1. Establish the model structure of GaAs3 and InAs3 thin films, optimize the structure by using the first-principles calculation software VASP, and read the energy value in OUTCAR to obtain the most stable primitive cell structure of GaAs3 and InAs3 thin films;

[0046] S2. Calculate the phonon spectra of GaAs3 and InAs3 thin film models using the first-principles calculation software VASP combined with the Phonopy package to determine their structural stability;

[0047] S3, using the first-principles calculation software VASP to calculate the band structure and state density of GaAs3 and InAs3 films, as well as the two-dimensional projection diagram of the valence band top (VBM) and conduction band bottom (CBM) of the first Brillouin zone;

[0048] S4. Based on the results calculated in step S3, the Seebeck coefficient S, electrical conductivity σ, and electronic thermal conductivity κ of GaAs3 and InAs3 films are calculated using Nanodcal calculation software. e , lattice thermal conductivity κ l And the thermoelectric figure of merit ZT.

[0049] Specifically, in step S1, the primitive cell structure along the zigzag direction and the armchair direction of the GaAs3 and InAs3 film surfaces is selected, and then a vacuum layer of a certain number of angstroms is added to the GaAs3 and InAs3 film surfaces to obtain an initial structure model. As a preferred embodiment, a vacuum layer of more than 15 angstroms is added to the GaAs3 and InAs3 film surfaces.

[0050] In step S1, after the model structure is established, the first principle calculation software VASP is used to relax the atomic position of the unit cell structure, wherein the cutoff energy is set to 500eV, the K point is set to 9×9×1, the electron convergence accuracy is 1E-8eV, and the ion convergence accuracy is

[0051] In step S2, the phonon spectra of the GaAs3 and InAs3 thin film models are calculated by first-principles calculation software VASP combined with Phonopy package to check whether there is an imaginary frequency, thereby judging the structural stability. Specifically, when the phonon spectrum does not have an imaginary frequency, it indicates that the structural stability is good, and when the phonon spectrum has an imaginary frequency, it indicates that the structural stability is poor.

[0052] In step S3, the unit cell structure optimized in step S2 is taken as the research object, and the first principle calculation software VASP is used to perform non-static self-consistent calculations, so as to calculate the band structure and state density of the unit cell structure. Among them, the interface structure is non-statically self-consistently calculated by the first principle calculation software VASP, so as to obtain the positions of the bottom of the conduction band and the top of the valence band of the interface structure. In the calculation process, the interface structure is divided into 9×9×1 K points.

[0053] In step S4, according to the results calculated in step S3, the Seebeck coefficient S, electrical conductivity σ, and electronic thermal conductivity κ of GaAs3 and InAs3 films are calculated using Nanodcal calculation software. e , lattice thermal conductivity κ l and thermoelectric figure of merit ZT, thereby obtaining theoretically high-performance thermoelectric materials.

[0054] Specifically, the calculation formulas for the above performance parameters are:

[0055] The calculation formula of Seebeck coefficient S is:

[0056] Among them, e is the electron charge, T is the absolute temperature;

[0057] The calculation formula of conductivity σ is:

[0058] σ=e 2 L0 / l, where e is the electron charge and l is the device length;

[0059] Electronic thermal conductivity κ e The calculation formula is:

[0060] Where, T is the absolute temperature and l is the length of the device;

[0061] Lattice thermal conductivity κ l The calculation formula is:

[0062] Where S is the Seebeck coefficient, h is the ratio of Planck constant to 2π, n is the nth phonon line, v n is the group velocity, ω n is the angular frequency of the lattice wave, f is the Fermi-Dirac distribution function, and T is the absolute temperature;

[0063] The calculation formula of thermoelectric figure of merit ZT is:

[0064] Where S is the Seebeck coefficient, α is the conductivity, T is the absolute temperature, κ e is the electronic thermal conductivity, κ l is the lattice thermal conductivity;

[0065] In the above formula, L0, L1 and L2 are obtained by the integral formula Where m = (0, 1, 2), h is Planck's constant, T e (ε) is the electron transmission spectrum, μ is the Fermi energy, and f is the Fermi-Dirac distribution function.

[0066] The unit cell structure of the GaAs3 and InAs3 film surfaces along the zigzag and armchair directions was optimized by the first-principles calculation software VASP, thereby obtaining a stable unit cell structure. The phonon spectrum was calculated by the Phonopy package to further determine its stability. The band structure and state density of the GaAs3 and InAs3 film structures were then obtained by performing non-static self-consistent calculations. Finally, the Seebeck coefficient, electrical conductivity, electronic and lattice thermal conductivity, and thermoelectric figure of merit ZT of the GaAs3 and InAs3 film surfaces along the zigzag and armchair directions were calculated by the Nanodcal calculation software, and then the high-performance thermoelectric structure was theoretically predicted, providing a theoretical basis and guidance for related experiments, saving experimental costs and improving the efficiency of thermoelectric material design.

[0067] In order to better understand the present invention, the following describes the design method of GaAs3 and InAs3 thin films with high thermoelectric performance at room temperature in conjunction with specific embodiments:

[0068] Embodiment 1:

[0069] Construct GaAs3 and InAs3 single-layer structures, add a 20 angstrom vacuum layer on the surface of GaAs3 and InAs3 films, and obtain the initial model structure. Figure 1 As shown;

[0070] The first-principles calculation software VASP was used to optimize the atomic positions of GaAs3 and InAs3 film structures. The calculation parameters in the optimization process were set as follows: the cutoff energy was set to 500eV, the K point was set to 9×9×1, the electron convergence accuracy was 1E-8eV, and the ion convergence accuracy was

[0071] The first-principles calculation software VASP combined with the Phonopy package was used to calculate the phonon spectra of GaAs3 and InAs3 thin film models to determine their structural stability, such as Figure 2 and Figure 3 As shown;

[0072] The non-static self-consistent calculations of each model were performed using the first-principles calculation software VASP, and the band structure and state density of GaAs3 and InAs3 film structures along the zigzag direction and armchair direction were obtained using a 9×9×1 K point division, as shown in the figure. Figure 4-Figure 7 As shown;

[0073] Nanodcal calculation software is used to calculate the Seebeck coefficient S, electrical conductivity σ, and electronic thermal conductivity κ of GaAs3 and InAs3 films. e , lattice thermal conductivity κ l And the thermoelectric figure of merit ZT. The results are as follows Figure 8-Figure 13 As shown;

[0074] in, Figure 2 and Figure 3 The calculation results of phonon spectra for GaAs3 and InAs3 films; Figure 4-Figure 7 The calculated results of band structure and density of states of GaAs3 and InAs3 films along the zigzag and armchair directions; Figure 8-Figure 13 The calculation results of thermoelectric parameters are Fig.13 It can be seen that GaAs3 has the highest thermoelectric figure of merit along the zigzag direction. The results show that both GaAs3 and InAs3 single-layer films have high thermoelectric conversion efficiency. At 300K, the thermoelectric figures of merit of p-type doping along the zigzag direction reach 3.75 and 3.78 respectively, with the best thermoelectric performance.

[0075] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may have various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention to be protected, and the scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A design method for GaAs3 and InAs3 thin film materials with high thermoelectric performance, characterized in that: Includes steps: S1. Establish the model structure of GaAs3 and InAs3 thin films, optimize the structure by using the first-principles calculation software VASP, and read the energy value in OUTCAR to obtain the most stable primitive cell structure of GaAs3 and InAs3 thin films; S2. Calculate the phonon spectra of GaAs3 and InAs3 thin film models using the first-principles calculation software VASP combined with the Phonopy package to determine their structural stability; S3, using the first-principles calculation software VASP to calculate the band structure and state density of GaAs3 and InAs3 films, as well as the two-dimensional projection diagram of the valence band top (VBM) and conduction band bottom (CBM) of the first Brillouin zone; S4. Based on the results calculated in step S3, the Seebeck coefficient S, electrical conductivity σ, and electronic thermal conductivity κ of GaAs3 and InAs3 films are calculated using Nanodcal calculation software. e , lattice thermal conductivity κ l And the thermoelectric figure of merit ZT.

2. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 1, characterized in that: In the step S1, a vacuum layer of more than 15 angstroms is added on the surface of the GaAs3 and InAs3 films.

3. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 1 or 2, characterized in that: In the step S1, a vacuum layer of 20 angstroms is added on the surface of the GaAs3 and InAs3 films.

4. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 1, characterized in that: The primitive cell structures along the zigzag direction and armchair direction of the GaAs3 and InAs3 film surfaces were selected.

5. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 4, characterized in that: In step S1, after the model structure is established, the first-principles calculation software VASP is used to relax the atomic positions of the unit cell structure, wherein the cutoff energy is set to 500 eV, the K point is set to 9×9×1, the electron convergence accuracy is 1E-8 eV, and the ion convergence accuracy is 6. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 4, characterized in that: In the step S3, the unit cell structure optimized in the step S2 is taken as a research object, and a non-static self-consistent calculation is performed using the first principle calculation software VASP, so as to calculate the band structure and state density of the unit cell structure.

7. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 6, characterized in that: The non-static self-consistent calculation of the primitive cell structure is divided into 9×9×1 K points.

8. The design method of GaAs3 and InAs3 thin film materials with high thermoelectric performance according to claim 1, characterized in that: In the step S4, The calculation formula of Seebeck coefficient S is: Among them, e is the electron charge, T is the absolute temperature; The calculation formula of conductivity σ is: σ=e 2 L0 / l, where e is the electron charge and l is the device length; Electronic thermal conductivity κ e The calculation formula is: Where, T is the absolute temperature and l is the length of the device; Lattice thermal conductivity κ l The calculation formula is: Where S is the Seebeck coefficient, h is the ratio of Planck constant to 2π, n is the nth phonon line, v n is the group velocity, ω n is the angular frequency of the lattice wave, f is the Fermi-Dirac distribution function, and T is the absolute temperature; The calculation formula of thermoelectric figure of merit ZT is: Where S is the Seebeck coefficient, α is the conductivity, T is the absolute temperature, κ e is the electronic thermal conductivity, κ l is the lattice thermal conductivity; In the above formula, L0, L1 and L2 are obtained by the integral formula Where m = (0, 1, 2), h is Planck's constant, T e (ε) is the electron transmission spectrum, μ is the Fermi energy, and f is the Fermi-Dirac distribution function.

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