A prediction method for the photoelectric conversion properties of van der Waals heterojunction regulated by ambient gas molecular intercalation

Abstract

The present invention belongs to the technical field of photocatalysis and solar cells, and specifically relates to a prediction method for regulating the photoelectric conversion properties of van der Waals heterojunctions by intercalation of ambient gas molecules. The prediction method provided by the present invention adopts a theoretical simulation method to construct an ambient gas molecule intercalation van der Waals heterojunction model, optimizes the stable configuration structure of the molecular intercalation heterojunction and performs energy statistics, and screens to obtain a ground state ambient gas molecule intercalation van der Waals heterojunction model; compared with an unintercalated van der Waals heterojunction supercell model, the ground state ambient gas molecule intercalation van der Waals heterojunction model is evaluated for electronic properties, carrier dynamics analysis, and non-adiabatic coupling average analysis, which can accurately and conveniently predict the effects of different ambient gas molecules on the photoelectric conversion properties of van der Waals heterojunctions. The prediction method provided by the present invention has the advantages of being simple and generalizable, and is applicable to the entire TMDC heterojunction family.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis and solar cell technology, specifically relating to a method for predicting the photoelectric conversion properties of van der Waals heterojunctions by intercalation of environmental gas molecules. Background Technology

[0002] The unique properties of two-dimensional materials have attracted considerable attention. Heterojunctions, formed by stacking different two-dimensional materials, offer new properties. For example, stacking two-dimensional materials allows for precise control of band structure alignment. Faced with the growing energy crisis and environmental pollution, developing clean, efficient, and sustainable energy sources, such as solar energy, is urgently needed. Type-two band structure heterojunctions can promote the spatial separation of photogenerated electron and hole pairs, showing great promise for applications in photocatalysts and solar cells.

[0003] Transition metal dichalcogenide (TMDC) van der Waals heterostructures have been shown to achieve ultrafast charge transfer. Current methods for synthesizing two-dimensional vertical heterostructures include mechanical assembly stacking, chemical vapor deposition, and physical epitaxy. However, these methods inevitably introduce ambient gas molecules into the interlayer during the forging and transfer of two-dimensional materials to form vertical heterostructures. Existing research shows that the introduction of metal ions into two-dimensional van der Waals heterostructures can significantly affect their photoelectric properties. Therefore, the influence of ambient gas molecule intercalation on the electronic properties of van der Waals heterostructures is also significant.

[0004] However, the effects of intercalation of reactive gas molecules (such as O2 and H2O molecules) in the environment on the photoelectric properties of van der Waals heterojunctions have not been reported. Summary of the Invention

[0005] The purpose of this invention is to provide a method for predicting the photoelectric conversion properties of van der Waals heterojunctions by intercalation of environmental gas molecules. The prediction method provided by this invention uses theoretical simulation to accurately and easily predict the influence of different environmental gas molecules on the photoelectric conversion properties of van der Waals heterojunctions.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for predicting the influence of environmental gas molecule intercalation on the photoelectric conversion properties of van der Waals heterojunctions, comprising the following steps:

[0008] (1) A van der Waals heterojunction primitive cell is constructed by stacking a first monolayer two-dimensional material primitive cell and a second monolayer two-dimensional material primitive cell along the direction perpendicular to the surface of the two-dimensional material; the van der Waals heterojunction primitive cell is expanded to obtain a van der Waals heterojunction supercell model.

[0009] (2) Intercalate environmental gas molecules at multiple non-equivalent sites in the van der Waals heterojunction supercell model to obtain molecular intercalation van der Waals heterojunction models with different intercalation sites; perform structural optimization on the intercalation van der Waals heterojunction models with different intercalation sites, perform energy statistics on the optimized intercalation van der Waals heterojunction models with different intercalation sites, and take the intercalation van der Waals heterojunction model with the lowest energy as the ground state environmental gas molecule intercalation van der Waals heterojunction model;

[0010] (3) Differential charge density analysis was performed on the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the interlayer coupling of the van der Waals heterojunction; projected density of states analysis was performed on the van der Waals heterojunction supercell model and the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the band gap and band arrangement of the van der Waals heterojunction.

[0011] (4) Molecular dynamics trajectory simulations were performed on the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the NVE ensemble. The carrier dynamics analysis was performed on the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the time-dependent density functional method. The influence of different environment gas molecule intercalation on the carrier dynamics of the van der Waals heterojunction was obtained.

[0012] (5) Perform non-adiabatic coupling average value analysis on the ground state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the non-adiabatic coupling average value of the van der Waals heterojunction.

[0013] There is no time order requirement between steps (3) and (4).

[0014] Preferably, the first monolayer two-dimensional material unit cell is a monolayer WSe2 unit cell, and the second monolayer two-dimensional material unit cell is a monolayer WS2 unit cell; the environmental gas molecules include O2 and / or gaseous H2O.

[0015] Preferably, in step (4), before performing the molecular dynamics trajectory simulation, the method is used to preheat the van der Waals heterojunction supercell model and the ground state environment gas molecule intercalation van der Waals heterojunction model respectively, and the preheating temperature is 300K.

[0016] Preferably, the lattice length of the van der Waals heterojunction supercell is >

[0017] Preferably, the method for constructing the van der Waals heterojunction supercell model includes the following steps:

[0018] The first monolayer two-dimensional material unit cell and the second monolayer two-dimensional material unit cell are stacked using C7 to obtain the van der Waals heterojunction unit cell.

[0019] The van der Waals heterojunction primitive cells are expanded using periodic boundary conditions to obtain the van der Waals heterojunction supercell.

[0020] Preferably, the inequivalent sites include one or more of interlayer bridge sites, interlayer vacancies, and apex sites.

[0021] Preferably, the energy statistics include the interlayer spacing of the intercalation van der Waals heterojunction model at different intercalation sites after statistical optimization, and the bond lengths and / or bond angles of the environmental gas molecules in the intercalation.

[0022] Preferably, the carrier dynamics include the separation and recombination of electrons and holes; the separation of electrons and holes includes the transfer of electrons and the transfer of holes.

[0023] Preferably, the structural optimization and energy statistics in step (2), as well as the differential charge density analysis and projected density of states analysis in step (3), all employ van der Waals correction.

[0024] Preferably, the structural optimization and energy statistics in step (2), as well as the differential charge density analysis and projected density of states analysis in step (3), are all performed using the VASP 6.3.0 software package; the cutoff energy is set to 500 eV, and the energy convergence criterion is: the range of energy variation of the model structure < 10 eV. -5 eV, change in force on an atom

[0025] This invention provides a method for predicting the influence of environmental gas molecule intercalation on the photoelectric conversion properties of van der Waals heterojunctions, comprising the following steps: (1) constructing van der Waals heterojunction units using a first monolayer two-dimensional material unit cell and a second monolayer two-dimensional material unit cell along a direction perpendicular to the surface of the two-dimensional material; expanding the van der Waals heterojunction unit cell to obtain a van der Waals heterojunction supercell model; (2) intercalating environmental gas molecules at multiple non-equivalent sites in the van der Waals heterojunction supercell model to obtain molecular intercalation van der Waals heterojunction models with different intercalation sites; performing structural optimization on the intercalation van der Waals heterojunction models with different intercalation sites, performing energy statistics on the optimized intercalation van der Waals heterojunction models with different intercalation sites, and selecting the intercalation van der Waals heterojunction model with the lowest energy to obtain a ground-state environmental gas molecule intercalation van der Waals heterojunction model; (3) performing differential charge density analysis on the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain different environmental gas molecules The influence of intercalation on the interlayer coupling of van der Waals heterojunction; the projection density of states analysis of the van der Waals heterojunction supercell model and the ground state environment gas molecule intercalation van der Waals heterojunction model is obtained to obtain the influence of different environment gas molecule intercalation on the band gap and band arrangement of the van der Waals heterojunction; (4) the molecular dynamics trajectory simulation of the van der Waals heterojunction supercell model and the ground state environment gas molecule intercalation van der Waals heterojunction model is performed by using the NVE ensemble, and the carrier dynamics analysis of the van der Waals heterojunction supercell model and the ground state environment gas molecule intercalation van der Waals heterojunction model is performed by using the time-dependent density functional method to obtain the influence of different environment gas molecule intercalation on the carrier dynamics of the van der Waals heterojunction; (5) the non-adiabatic coupling average value analysis of the ground state environment gas molecule intercalation van der Waals heterojunction model is performed to obtain the influence of different environment gas molecule intercalation on the non-adiabatic coupling average value of the van der Waals heterojunction; there is no time order limitation between steps (3) and (4). The prediction method provided by this invention employs theoretical simulation to construct a van der Waals heterojunction model with intercalated ambient gas molecules. This involves optimizing the stable configuration of the intercalated heterojunction and performing energy statistics to screen and obtain a ground-state model. Compared to the supercell model of an unintercalated van der Waals heterojunction, this method evaluates the electronic properties (differential charge density analysis and projected density of states analysis), performs carrier dynamics analysis, and non-adiabatic coupling average value analysis on the ground-state model with intercalated ambient gas molecules. This allows for accurate and convenient prediction of the influence of different ambient gas molecules on the photoelectric conversion properties of the van der Waals heterojunction. The prediction method provided by this invention has the advantages of simplicity and scalability, and is applicable to the entire TMDC heterojunction family. Furthermore, since the intercalation of ambient gas molecules is inevitable in the synthesis and stacking of van der Waals heterojunctions, the prediction method provided by this invention can accurately predict the influence of ambient gas molecules on the photoelectric conversion properties of the van der Waals heterojunction, showing great application potential in the fields of photocatalysis and solar cells.

[0026] Furthermore, in this invention, the first monolayer two-dimensional material unit cell is a monolayer WSe2 unit cell, and the second monolayer two-dimensional material unit cell is a monolayer WS2 unit cell; the ambient gas molecules include O2 and / or gaseous H2O. This invention targets the WSe2 / WS2 heterojunction. After the intercalation of ambient gas molecules (O2 and gaseous H2O), the WSe2 / WS2 heterojunction structure exhibits the following advantages: faster electron transfer than the original WSe2 / WS2 heterojunction. The unique interlayer confinement environment of the WSe2 / WS2 heterojunction effectively activates O2 molecules, causing them to spontaneously dissociate between layers. Compared to the original heterojunction, the band gap decreases by 0.27 eV, but the type-II band arrangement remains unchanged. Furthermore, the electron transfer time of the WSe2 / WS2 van der Waals heterojunction after O2 molecule intercalation is only half that of the original heterojunction. The H2O molecule intercalation in the WSe2 / WS2 heterojunction effectively extends the carrier lifetime. H2O molecule intercalation increases the interlayer distance of the heterojunction. Since the H2O molecules do not dissociate, the van der Waals band gap decreases by 0.18 eV, while the type-II bandgap remains unchanged. The carrier lifetime of the H2O-intercalated heterojunction is 20 nanoseconds longer than that of the original heterojunction. Furthermore, H2O molecule intercalation promotes hole transfer, reducing the hole transfer time to one-third that of the original heterojunction, achieving robust spatial separation of electrons and holes. Therefore, robust charge spatial separation can be achieved in the fabrication of WSe2 / WS2 heterojunctions through water molecule intercalation. Attached Figure Description

[0027] Figure 1 To study the flow chart of carrier dynamics in WSe2 / WS2 van der Waals heterojunction regulated by intercalated molecules O2 and H2O;

[0028] Figure 2 Schematic diagrams of the structures of WSe2 / WS2, WSe2 / O2 / WS2 and WSe2 / H2O / WS2 van der Waals heterojunctions;

[0029] Figure 3 Schematic diagram of band arrangement and carrier separation and recombination for WSe2 / WS2, WSe2 / O2 / WS2 and WSe2 / H2O / WS2 van der Waals heterojunctions;

[0030] Figure 4 This is a schematic diagram illustrating the van der Waals heterojunction supercell obtained by expanding the cell in a specific embodiment of the present invention. Detailed Implementation

[0031] This invention provides a method for predicting the influence of environmental gas molecule intercalation on the photoelectric conversion properties of van der Waals heterojunctions, comprising the following steps:

[0032] (1) A van der Waals heterojunction primitive cell is constructed by using a first monolayer two-dimensional material primitive cell and a second monolayer two-dimensional material primitive cell along the direction perpendicular to the surface of the two-dimensional material; the van der Waals heterojunction primitive cell is expanded to obtain a van der Waals heterojunction supercell model.

[0033] (2) Intercalate environmental gas molecules at multiple non-equivalent sites in the van der Waals heterojunction supercell model to obtain molecular intercalation van der Waals heterojunction models with different intercalation sites; perform structural optimization on the intercalation van der Waals heterojunction models with different intercalation sites, perform energy statistics on the optimized intercalation van der Waals heterojunction models with different intercalation sites, and take the intercalation van der Waals heterojunction model with the lowest energy as the ground state environmental gas molecule intercalation van der Waals heterojunction model;

[0034] (3) Differential charge density analysis was performed on the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the interlayer coupling of the van der Waals heterojunction; projected density of states analysis was performed on the van der Waals heterojunction supercell model and the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the band gap and band arrangement of the van der Waals heterojunction.

[0035] (4) Molecular dynamics trajectory simulations were performed on the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the NVE ensemble. The carrier dynamics analysis was performed on the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the time-dependent density functional method. The influence of different environment gas molecule intercalation on the carrier dynamics of the van der Waals heterojunction was obtained.

[0036] (5) Perform non-adiabatic coupling average value analysis on the ground state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalation on the non-adiabatic coupling average value of the van der Waals heterojunction.

[0037] There is no time order requirement between steps (3) and (4).

[0038] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0039] This invention constructs van der Waals heterojunction primitive cells by stacking a first monolayer two-dimensional material primitive cell and a second monolayer two-dimensional material primitive cell along a direction perpendicular to the surface of the two-dimensional material; the van der Waals heterojunction primitive cells are expanded to obtain a van der Waals heterojunction supercell model.

[0040] In this invention, the first monolayer two-dimensional material unit cell is preferably a monolayer WSe2 unit cell.

[0041] In this invention, the second monolayer two-dimensional material unit cell is preferably a monolayer WS2 unit cell.

[0042] In this invention, the method for constructing the van der Waals heterojunction supercell preferably includes the following steps:

[0043] The first monolayer two-dimensional material unit cell and the second monolayer two-dimensional material unit cell are stacked using C7 to obtain the van der Waals heterojunction unit cell.

[0044] The van der Waals heterojunction primitive cells are expanded using periodic boundary conditions to obtain the van der Waals heterojunction supercell.

[0045] The present invention stacks the first monolayer two-dimensional material unit cell and the second monolayer two-dimensional material unit cell using C7 to obtain a van der Waals heterojunction unit cell.

[0046] Before performing the C7 stacking, the present invention preferably optimizes the structure of the first monolayer two-dimensional material unit cell and the second monolayer two-dimensional material unit cell respectively. In the present invention, the structural optimization is preferably performed using the VASP6.3.0 software package, and the present invention does not have special requirements for the specific implementation of the structural optimization using the VASP6.3.0 software package.

[0047] The present invention preferably calculates the lattice constant of the first monolayer two-dimensional material unit cell and the lattice constant of the second monolayer two-dimensional material unit cell, and takes the average value of the lattice constant of the first monolayer two-dimensional material unit cell and the lattice constant of the second monolayer two-dimensional material unit cell as the lattice constant of the van der Waals heterojunction unit cell, with a mismatch degree of 2%.

[0048] In this invention, when the first monolayer two-dimensional material unit cell is preferably a monolayer WSe2 unit cell, and the second monolayer two-dimensional material unit cell is preferably a monolayer WS2 unit cell, the C7 stacking is preferably such that the W atoms of the monolayer WSe2 unit cell (upper layer) face the S atoms of the monolayer WS2 unit cell (lower layer), and the Se atoms of the monolayer WSe2 unit cell (upper layer) face the W atoms of the monolayer WS2 unit cell (lower layer).

[0049] In this invention, when the first monolayer two-dimensional material unit cell is preferably a monolayer WSe2 unit cell and the second monolayer two-dimensional material unit cell is preferably a monolayer WS2 unit cell, the van der Waals heterojunction unit cell is a WSe2 / WS2 heterojunction unit cell, and the WSe2 / WS2 heterojunction unit cell is a rhombic unit cell with lattice constants of a = b, α = β = 120°, and γ = 90°.

[0050] To conserve computational resources, this invention preferably transforms the WSe2 / WS2 heterojunction rhombic unit cell into an orthorhombic unit cell, with the following lattice constant: α = β = γ = 90°. The present invention preferably expands the WSe2 / WS2 heterojunction orthogonal primitive cell.

[0051] After obtaining the van der Waals heterojunction primitive cells, the present invention expands the van der Waals heterojunction primitive cells using periodic boundary conditions to obtain the van der Waals heterojunction supercell.

[0052] In this invention, the purpose of the cell expansion is to ensure that the distance between the intercalated molecules is far enough to avoid interactions between them.

[0053] In this invention, the van der Waals heterojunction supercell structure model utilizes periodic boundary conditions to represent infinitely extended two-dimensional materials. In this invention, the van der Waals heterojunction supercell is a periodic arrangement of countless single cells; therefore, this invention requires a cell expansion greater than [a certain size]. (Length unit, angstrom), otherwise adjacent intercalated molecules will interact, affecting the accuracy of the calculation results. For example... Figure 4 As shown, the preferred calculation method of this invention uses the smallest unit cell contained in the red box, but in reality, the periodic boundary conditions are an arrangement of countless smallest unit cells.

[0054] In this invention, the lattice length of the van der Waals heterojunction supercell is preferably...

[0055] In a specific embodiment of the present invention, the van der Waals heterojunction primitive cell is preferably expanded by a factor of 3 along the x and y directions and by a factor of 1 along the z direction, i.e., a 3×3×1 cell expansion is performed. In the present invention, the lattice length of the resulting van der Waals heterojunction supercell after the 3×3×1 cell expansion is preferably...

[0056] In a specific embodiment of the present invention, the van der Waals heterojunction supercell model specifically includes the WSe2 / WS2 heterojunction supercell model.

[0057] After obtaining the van der Waals heterojunction supercell model, the present invention intercalates environmental gas molecules at multiple non-equivalent sites in the van der Waals heterojunction supercell model to obtain molecular intercalation van der Waals heterojunction models with different intercalation sites; the structure of the intercalation van der Waals heterojunction models with different intercalation sites is optimized, and energy statistics are performed on the optimized intercalation van der Waals heterojunction models with different intercalation sites. The intercalation van der Waals heterojunction model with the lowest energy is selected to obtain the ground state environmental gas molecule intercalation van der Waals heterojunction model.

[0058] In this invention, the environmental gas molecules preferably include O2 and / or gaseous H2O, more preferably O2 or gaseous H2O.

[0059] In this invention, the inequivalent site preferably includes one or more of interlayer bridging sites, interlayer vacancy sites, and apex sites, and more preferably interlayer bridging sites, interlayer vacancy sites, or apex sites.

[0060] In this invention, prior to the intercalation, the environmental gas molecules are preferably structurally optimized, and the optimized environmental gas molecules are then used for the intercalation. Preferably, the optimization of the structure of the environmental gas molecules under vacuum conditions yields stable bond lengths and / or bond angles under vacuum conditions. Preferably, the structural optimization is performed using the VASP6.3.0 software package, and there are no specific requirements for the specific implementation method of using the VASP6.3.0 software package for structural optimization.

[0061] In this invention, one environmental gas molecule is intercalated at any one non-equivalent site in the van der Waals heterojunction supercell model to obtain a molecularly intercalated van der Waals heterojunction model.

[0062] In a specific embodiment of the present invention, the molecular intercalation van der Waals heterojunction model includes O2 intercalation WSe2 / WS2 heterojunctions (WSe2 / O2 / WS2) with different intercalation sites and H2O intercalation WSe2 / WS2 heterojunctions (WSe2 / H2O / WS2) with different intercalation sites.

[0063] In this invention, the method for constructing WSe2 / O2 / WS2 at different intercalation sites preferably includes the following steps:

[0064] Establish a lattice constant as The O2 molecule was placed into the crystal lattice model and the structure was optimized using the VASP6.3.0 software package. The optimized O2 molecule was then intercalated into any one non-equivalent site in the interlayer of the WSe2 / WS2 heterojunction supercell model to obtain WSe2 / O2 / WS2 with different intercalation sites.

[0065] In this invention, the method for constructing WSe2 / H2O / WS2 at different intercalation sites preferably includes the following steps:

[0066] Establish a lattice constant as The lattice model was used to place H2O molecules into the lattice model and perform structural optimization using the VASP6.3.0 software package. The optimized H2O molecule was then intercalated into any one non-equivalent site in the interlayer of the WSe2 / WS2 heterojunction supercell model to obtain WSe2 / H2O / WS2 with different intercalation sites.

[0067] After obtaining molecular intercalation van der Waals heterojunction models with different intercalation sites, this invention performs structural optimization on the intercalation van der Waals heterojunction models with different intercalation sites, performs energy statistics on the optimized intercalation van der Waals heterojunction models with different intercalation sites, and selects the intercalation van der Waals heterojunction model with the lowest energy to obtain the ground state environment gas molecular intercalation van der Waals heterojunction model.

[0068] When optimizing the structure of the intercalation van der Waals heterojunction model at different intercalation sites, this invention preferably considers van der Waals correction. In this invention, the van der Waals correction preferably includes DFT-D2 and IVDW=10.

[0069] When performing structural optimization of the intercalation van der Waals heterojunction model at different intercalation sites, the present invention preferably uses the VASP6.3.0 software package; the cutoff energy is preferably set to 500 eV, and the energy convergence criterion is preferably: the range of energy variation of the model structure is <10 eV. -5 eV, change in force on an atom

[0070] In this invention, the energy statistics include the interlayer spacing of the intercalation van der Waals heterojunction model at different intercalation sites after statistical optimization, and the bond lengths and / or bond angles of the environmental gas molecules in the statistical intercalation.

[0071] When performing energy statistics on the optimized intercalation van der Waals heterojunction models at different intercalation sites, this invention preferably considers van der Waals corrections. In this invention, the van der Waals corrections preferably include DFT-D2 and IVDW = 10.

[0072] When performing energy statistics on the optimized intercalation van der Waals heterojunction model with different intercalation sites, this invention preferably uses the VASP 6.3.0 software package; the cutoff energy is preferably set to 500 eV, and the energy convergence criterion is preferably: the range of energy variation of the model structure < 10 eV. -5 eV, change in force on an atom

[0073] In this invention, the optimized intercalation van der Waals heterojunction model with different intercalation sites is preferably an optimized WSe2 / O2 / WS2 model with different intercalation sites. The energy statistics preferably include the interlayer spacing and OO bond length of the optimized WSe2 / O2 / WS2 model with different intercalation sites.

[0074] According to the interlayer spacing statistics of the present invention, the interlayer spacing of van der Waals heterojunctions increases after the intercalation of ambient gas molecules. The interlayer spacing of H2O molecules is the largest, followed by O2 molecules, and lastly the intercalation of unintercalated van der Waals heterojunctions.

[0075] In this invention, the optimized intercalation van der Waals heterojunction model with different intercalation sites is preferably the optimized WSe2 / H2O / WS2 model with different intercalation sites. The energy statistics preferably include the interlayer spacing, HOH bond length and bond angle of the optimized WSe2 / H2O / WS2 model with different intercalation sites.

[0076] As a specific embodiment of the present invention, the present invention preferably compares the bond lengths and / or bond angles of the environmental gas molecules obtained by energy statistics with the stable bond lengths and / or bond angles of the environmental gas molecules under vacuum conditions.

[0077] After obtaining the ground-state environmental gas molecule intercalation van der Waals heterojunction model, differential charge density analysis was performed on the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalations on the interlayer coupling of the van der Waals heterojunction; projected density of states analysis was performed on the van der Waals heterojunction supercell model and the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalations on the band gap and band arrangement of the van der Waals heterojunction.

[0078] When performing differential charge density analysis on the ground-state environment gas molecule intercalation van der Waals heterojunction model, this invention preferably considers van der Waals correction. In this invention, the van der Waals correction preferably includes DFT-D2, IVDW = 10.

[0079] When performing differential charge density analysis on the ground-state environment gas molecule intercalation van der Waals heterojunction model, the present invention preferably uses the VASP 6.3.0 software package; the cutoff energy is preferably set to 500 eV, and the energy convergence criterion is preferably: the range of energy variation of the model structure < 10 -5 eV, change in force on an atom

[0080] In this invention, the method for obtaining the differential charge density preferably includes the following steps:

[0081] The total charge density of the ground-state ambient gas molecule intercalation van der Waals heterojunction model was calculated and output using the VASP6.3.0 software package.

[0082] The charge density of each component in the ground-state environmental gas molecule intercalation van der Waals heterojunction model was calculated and output using the VASP6.3.0 software package.

[0083] The differential charge density is obtained by subtracting the charge density of each component from the total charge density.

[0084] In this invention, when using the VASP6.3.0 software package to calculate and output the charge density of each component of the ground-state environmental gas molecule intercalation van der Waals heterojunction model, the lattice size of each component is always kept the same as the lattice size of the ground-state environmental gas molecule intercalation van der Waals heterojunction model.

[0085] In this invention, the effect of different ambient gas molecule intercalation obtained from differential charge density analysis on the interlayer coupling of the van der Waals heterojunction is specifically as follows: after the ambient gas molecule intercalation, the interlayer charge of the van der Waals heterojunction is redistributed, indicating a significant change in interlayer coupling. In this invention, the ambient gas molecule is preferably O2; that is, after O2 intercalation, the O2 molecule gains electrons from the heterojunction, thereby promoting the dissociation of the O2 molecule. In this invention, when the ambient gas molecule is preferably gaseous H2O, that is, after H2O molecule intercalation, the heterojunction provides a small number of electrons to the H2O molecule.

[0086] In this invention, when performing projected density of states analysis on van der Waals heterojunction supercell models and ground-state environment gas molecule intercalation van der Waals heterojunction models, van der Waals corrections are preferably considered. In this invention, the van der Waals corrections preferably include DFT-D2, with IVDW = 10.

[0087] In this invention, the VASP 6.3.0 software package is preferably used for projected density of states analysis of van der Waals heterojunction supercell models and ground-state environment gas molecule intercalation van der Waals heterojunction models; the cutoff energy is preferably set to 500 eV, and the energy convergence criterion is preferably: the range of energy variation of the model structure is <10 eV. -5 eV, change in force on an atom

[0088] In this invention, the method for obtaining the projected density of states of the van der Waals heterojunction supercell model preferably includes the following steps:

[0089] The projected density of states of the first monolayer two-dimensional material unit cell and the second monolayer two-dimensional material unit cell are calculated respectively, and the two are summed to obtain the projected density of states of the van der Waals heterostructure supercell model.

[0090] In this invention, the method for obtaining the projected density of states of the ground-state environmental gas molecule intercalation van der Waals heterojunction model preferably includes the following steps:

[0091] The projected density of states of the environmental gas molecules, the first monolayer two-dimensional material unit cell, and the second monolayer two-dimensional material unit cell are calculated separately. The three are then summed to obtain the projected density of states of the ground-state environmental gas molecule intercalated van der Waals heterojunction model.

[0092] The preferred method for the projected density of states analysis is to analyze the magnitude difference between the projected density of states of the ground-state environmental gas molecule intercalation van der Waals heterojunction model and the projected density of states of the van der Waals heterojunction supercell model.

[0093] In this invention, projected density of states analysis is performed on a van der Waals heterojunction supercell model and a ground-state ambient gas molecule intercalation van der Waals heterojunction model. The specific effects of different ambient gas molecule intercalations on the band gap of the van der Waals heterojunction are as follows: the band gap of the intercalated heterojunction is smaller compared to the unintercalated van der Waals heterojunction. In this invention, the ambient gas molecule is preferably O2, resulting in a 0.27 eV reduction in the WSe2 / O2 / WS2 band gap. Alternatively, the ambient gas molecule is preferably H2O, resulting in a 0.18 eV reduction in the WSe2 / H2O / WS2 band gap.

[0094] In this invention, projected density of states analysis is performed on a van der Waals heterojunction supercell model and a ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalations on the band arrangement of the van der Waals heterojunction. Specifically, this includes using the definition of type II band arrangement, where in a heterojunction composed of two materials, the conduction band bottom (CBM) and valence band top (VBM) of one material are higher than the CBM and VBM of the other material, respectively. In this invention, the band arrangements of the intercalated heterojunctions (WSe2 / H2O / WS2 and WSe2 / O2 / WS2) and the unintercalated van der Waals heterojunction (WSe2 / WS2) are both type II band arrangements. The CBM of WSe2 is higher than that of WS2; therefore, the CBM of WS2 is the CBM of the heterojunction. And the VBM of WSe2 is higher than that of WS2; therefore, the VBM of WSe2 is the VBM of the heterojunction. The intercalation of O2 and H2O molecules did not alter the band arrangement of the van der Waals heterojunction (WSe2 / WS2).

[0095] This invention employs the NVE ensemble to simulate molecular dynamics trajectories in both the van der Waals heterojunction supercell model and the ground-state ambient gas molecule intercalation van der Waals heterojunction model. Time-dependent density functional theory is then used to analyze carrier dynamics in both models, revealing the influence of different ambient gas molecule intercalations on the carrier dynamics of the van der Waals heterojunction.

[0096] In this invention, prior to performing the molecular dynamics trajectory simulation, the invention preferably further includes: preheating the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the AIMD method, and then performing the molecular dynamics trajectory simulation on the preheated van der Waals heterojunction supercell model and the preheated ground-state environment gas molecule intercalation van der Waals heterojunction model respectively; the preheating temperature is preferably 300K. In this invention, the AIMD method is specifically preferably the speed readjustment method using the VASP 6.3.0 software package.

[0097] The preferred implementation method for simulating molecular dynamics trajectories of the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model using the NVE ensemble is as follows: Molecular dynamics trajectories are simulated within 5000 steps under the NVE ensemble; the step size is preferably 1 femtosecond (fs). In this invention, the initial and final temperatures of both the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model are preferably 300 K during the molecular dynamics trajectory simulation. Both the van der Waals heterojunction supercell model and the ground-state environment gas molecule intercalation van der Waals heterojunction model maintain thermodynamic stability at 300 K.

[0098] In this invention, the carrier dynamics include the separation and recombination of electrons and holes; the separation of electrons and holes includes the transfer of electrons and the transfer of holes.

[0099] The preferred method for analyzing carrier dynamics in van der Waals heterojunction supercell models using time-dependent density functional theory in this invention is as follows: When analyzing the separation process of electrons and holes, 100 van der Waals heterojunction supercell models are selected, and 20,000 trajectories are sampled within the last 3 picoseconds of a 5-picosecond interval to obtain the time-varying energy level evolution and the change in electron energy over time. To analyze the electron lifetime, 50 van der Waals heterojunction supercell models are used, and 500 trajectories are sampled within 2 nanoseconds to obtain the energy distribution change of electrons over time.

[0100] The preferred method for carrier dynamics analysis of ground-state gas molecule intercalation van der Waals heterojunction models using time-dependent density functional theory in this invention is as follows: When analyzing the separation process of electrons and holes, 100 ground-state gas molecule intercalation van der Waals heterojunction models are selected, and 20,000 trajectories are sampled in the last 2 picoseconds to obtain the time-varying energy level evolution and the change of electron energy over time. When analyzing the electron lifetime, 50 ground-state gas molecule intercalation van der Waals heterojunction models are used, and 500 trajectories are sampled in 2 nanoseconds to obtain the change in electron energy distribution over time.

[0101] The present invention preferably obtains the photogenerated charge lifetime by fitting the e-exponential decay based on the relationship between the energy of electrons and time.

[0102] In this invention, due to the significant band gap in the electron-hole recombination process, the present invention preferably considers the quantum decoherence effect to simulate the recombination process of electrons and holes.

[0103] In a specific embodiment of the present invention, the preferred effect of different environmental gas molecule intercalations on the carrier dynamics of the van der Waals heterojunction is as follows: the electron-hole separation processes of WSe2 / WS2, WSe2 / O2 / WS2, and WSe2 / H2O / WS2 are at the picosecond level, while the electron-hole recombination time is at the nanosecond level, indicating that the recombination process is significantly slower than the separation time. For WSe2 / O2 / WS2, the electron separation time is half that of the original heterojunction, while the hole separation time is 7 times slower than that of the original heterojunction. For WSe2 / H2O / WS2, the hole separation time is only 1 / 3 that of the original heterojunction, while the recombination time is extended by 20 nanoseconds compared to the original WSe2 / WS2 heterojunction. This indicates that the heterojunction with H2O molecule intercalation can effectively extend the carrier lifetime.

[0104] This invention performs a non-adiabatic coupling average value analysis on the ground-state environmental gas molecule intercalation van der Waals heterojunction model to obtain the influence of different environmental gas molecule intercalations on the non-adiabatic coupling average value of the van der Waals heterojunction.

[0105] The present invention does not have any special requirements for the method of obtaining the average value of the non-adiabatic coupling.

[0106] In a specific embodiment of the present invention, the average value of non-adiabatic coupling in the ground-state gas molecule intercalation van der Waals heterojunction model is analyzed, and the average value of non-adiabatic coupling between the frontier orbitals near the VBM and CBM is calculated. During electron transfer, the average value of non-adiabatic coupling of WSe2 / O2 / WS2 is the largest, explaining its fastest electron transfer time. During hole transfer, the average value of non-adiabatic coupling of WSe2 / H2O / WS2 is the largest, indicating its fastest hole transfer time. During recombination, the average value of non-adiabatic coupling of WSe2 / H2O / WS2 is the smallest, indicating its longest recombination time.

[0107] This invention relates to the fields of photocatalysis and solar cell research, and discloses a simulation method for regulating the carrier lifetime of van der Waals heterojunctions by intercalating ambient gas molecules. The method includes constructing O2 and H2O molecularly intercalated van der Waals heterojunction models, screening stable configurations of the molecularly intercalated heterojunctions, evaluating electronic properties, determining the separation time of photogenerated electrons and holes, estimating the lifetime of photogenerated carriers, and understanding the mechanism by which molecular intercalation regulates carrier dynamics. Through screening, a molecularly intercalated heterojunction system (WSe2 / H2O / WS2 van der Waals heterojunction) capable of extending carrier lifetime is proposed. This van der Waals heterojunction material provides a unique interlayer confinement environment that can activate O2 and H2O molecules; O2 molecules can spontaneously dissociate, while H2O molecules do not. After molecular intercalation, the type II band structure of the WSe2 / WS2 van der Waals heterojunction remains unchanged. After H2O molecule intercalation, compared with the original heterojunction, photogenerated holes can be transferred rapidly, the carrier lifetime is extended by 20 nanoseconds, and photogenerated electron-hole pairs are effectively separated spatially, which has great application prospects in the fields of photocatalysis and solar cells.

[0108] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0109] Example 1

[0110] First, the unit cells of monolayer WSe2 and monolayer WS2 were structurally optimized using the VASP6.3.0 software package. The average value of the lattice constants of the two unit cells was calculated as the lattice constant of the WSe2 / WS2 heterojunction, with a mismatch of 2%. A C7 stacking configuration was established (i.e., the W atoms of the upper monolayer WSe2 unit cell are aligned with the S atoms of the lower monolayer WS2 unit cell, and the Se atoms of the upper monolayer WS2 unit cell are aligned with the W atoms of the lower monolayer WS2 unit cell) to obtain the rhombic unit cell of the WSe2 / WS2 heterojunction (lattice constants: a=b, α=β=120°, γ=90°).

[0111] To conserve computational resources, the rhombic unit cell of the WSe2 / WS2 heterojunction is transformed into an orthorhombic unit cell of the WSe2 / WS2 heterojunction (lattice constant: (a, α=β=γ=90°). Then, to avoid interactions between intercalated molecules, the WSe2 / WS2 heterojunction orthogonal unit cell was expanded into a 3×3×1 WSe2 / WS2 heterojunction supercell using periodic boundary conditions;

[0112] Establish a structural model of the O2 molecule, and then establish a lattice constant as... The O2 molecules were placed into the crystal lattice and then the structure was optimized using the VASP6.3.0 software package. Next, the optimized O2 molecules were intercalated into the interlayer non-equivalent sites of the WSe2 / WS2 heterojunction supercell, including bridge sites, apex sites, and vacancies, and the structure was optimized again using the VASP6.3.0 software package. The VASP6.3.0 software package parameters included: a cutoff energy of 500 eV, and an energy convergence criterion that the energy variation of the model structure was less than 10 eV. -5 eV, the change in force on the atom is less than The changes in interlayer spacing and OO bond length were statistically analyzed, and then the energies of different intercalation sites were compared to obtain the ground-state O2 molecule intercalation WSe2 / WS2 heterojunction structure, which is the ground-state WSe2 / O2 / WS2.

[0113] Establish a structural model of the H2O molecule, and then establish a lattice constant of... The H2O molecules were placed into the crystal lattice and then optimized using the VASP6.3.0 software package. Subsequently, the optimized H2O molecules were intercalated into the interlayer non-equivalent sites of the WSe2 / WS2 heterojunction supercell, including bridge sites, apex sites, and vacancies, and optimized again using the VASP6.3.0 software package. The VASP6.3.0 software package parameters included: a cutoff energy of 500 eV, and an energy convergence criterion that the energy variation of the model structure was less than 10 eV. -5 eV, the change in force on the atom is less than The changes in interlayer spacing, OH bond length and HOH bond angle were statistically analyzed, and the energies of different structures were compared to obtain the ground-state H2O molecule intercalation WSe2 / WS2 heterojunction structure, namely the ground-state WSe2 / H2O / WS2.

[0114] According to the statistical results of interlayer spacing, this embodiment found that the interlayer spacing increased after molecular intercalation. The interlayer spacing of H2O molecules was the largest, followed by O2 molecules, and finally WSe2 / WS2 heterojunction supercells.

[0115] Because it involves gas molecules and interlayer adsorption as well as interlayer van der Waals interactions, van der Waals corrections (DFT-D2, IVDW=10) are considered in the acquisition of ground state WSe2 / O2 / WS2 and ground state WSe2 / H2O / WS2.

[0116] Subsequently, differential charge density calculations were performed on the ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2. The calculation method involved using the VASP6.3.0 software package to output the total charge density of the entire intercalation system for ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2. Then, the charge density of each component of ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2 was calculated separately (wherein, the lattice size of each component remained the same as that of ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2). The differential charge density was then obtained by subtracting the charge density of each individual component from the total charge density of the intercalated heterojunction. After O2 or H2O molecule intercalation, the differential charge density indicates a redistribution of interlayer charge, suggesting a significant change in interlayer coupling. After O2 intercalation, O2 molecules gained electrons from the heterojunction, thereby promoting the dissociation of O2 molecules. After the H2O molecule is intercalated, the heterojunction provides a small number of electrons to the H2O molecule;

[0117] The electronic properties of ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2 were analyzed. The projected density of states of the WSe2 / WS2 heterojunction supercell, ground-state WSe2 / O2 / WS2, and ground-state WSe2 / H2O / WS2 were calculated using the VASP 6.3.0 software package. The WSe2 / WS2 heterojunction supercell, ground-state WSe2 / O2 / WS2, and ground-state WSe2 / H2O / WS2 were preheated to 300K using the rate readjustment method with the VASP 6.3.0 software package. Based on the preheated structures, in... In the NVE ensemble, molecular dynamics were calculated for 5000 steps (corresponding to 5000 fs), and then time-dependent density functional theory was used to study carrier separation and recombination processes. For the electron-hole separation process, 100 WSe2 / WS2 heterojunction supercells were selected, and 20,000 trajectories were sampled in the last 3 picoseconds of the 5 picosecond interval to obtain the time-varying energy level evolution and the change of electron energy over time. To assess the electron lifetime, 500 trajectories were sampled in 2 nanoseconds from 50 WSe2 / WS2 heterojunction supercells to obtain the change of electron energy distribution over time.

[0118] The difference between the ground-state WSe2 / O2 / WS2 and the WSe2 / WS2 heterojunction supercell setting is that, during the electron-hole separation process, the ground-state WSe2 / O2 / WS2 samples 20,000 trajectories in the last 2 picoseconds after 5 picoseconds.

[0119] Compared to the WSe2 / WS2 heterojunction supercell, the ground-state WSe2 / H2O / WS2 sampled 20,000 trajectories in the last 2 picoseconds during the electron-hole separation process;

[0120] Then, the lifetime of photogenerated charge is obtained by fitting the e-exponential decay based on the relationship between electron energy and time.

[0121] Analysis of the electronic properties of ground-state WSe2 / O2 / WS2 and ground-state WSe2 / H2O / WS2 shows that the electron-hole separation process of each of WSe2 / WS2, WSe2 / O2 / WS2, and WSe2 / H2O / WS2 is on the picosecond level, while the electron-hole recombination time is on the nanosecond level, indicating that the recombination process is significantly slower than the separation time. For WSe2 / O2 / WS2, the electron separation time is half that of the original heterojunction, while the hole separation time is 7 times slower than that of the original heterojunction. For WSe2 / H2O / WS2, the hole separation time is only one-third that of the original heterojunction, while the recombination time is extended by 20 nanoseconds compared to WSe2 / WS2. This indicates that the heterojunction with H2O molecule intercalation can effectively extend the carrier lifetime.

[0122] Finally, the average non-adiabatic coupling values ​​between the orbitals of the WSe2 / WS2 heterojunction supercell, ground-state WSe2 / O2 / WS2, and ground-state WSe2 / H2O / WS2 were calculated and analyzed. The average non-adiabatic coupling values ​​between the frontier orbitals near the VBM and CBM were also calculated. During electron transfer, the average non-adiabatic coupling value of WSe2 / O2 / WS2 was the largest, explaining that it has the fastest electron transfer time. During hole transfer, the average non-adiabatic coupling value of WSe2 / H2O / WS2 was the largest, indicating that it has the fastest hole transfer time. During recombination, the average non-adiabatic coupling value of WSe2 / H2O / WS2 was the smallest, indicating that it has the longest recombination time.

[0123] This invention utilizes theoretical simulations to construct a WSe2 / WS2 van der Waals heterojunction with intercalated ambient gas molecules (O2, H2O). Results show that the most stable configuration of O2 molecules at the heterojunction interface is one that tends towards dissociation. This is because O2 molecules can effectively capture electrons from the heterojunction, leading to spontaneous dissociation. Both O2 and H2O molecules can modulate the charge carrier dynamics of the heterojunction. Most importantly, this invention reveals for the first time that H2O molecule intercalation can effectively extend carrier lifetime, a previously undiscovered phenomenon. This invention promotes the application of TMDC materials in photocatalysis and solar cells.

[0124] Figure 1 The flowchart of the invention is designed to study the carrier dynamics of WSe2 / WS2 van der Waals heterojunctions regulated by intercalated molecules O2 and H2O. As can be seen from the flowchart, the work of this invention mainly consists of two parts: first, the construction of the structure of the molecular intercalation model, and second, the study of the carrier dynamics of the molecular intercalation heterojunction.

[0125] Figure 2Schematic diagrams of the structures of WSe2 / WS2, WSe2 / O2 / WS2, and WSe2 / H2O / WS2 van der Waals heterojunctions, from... Figure 2 As can be seen, O2 molecules spontaneously dissociate into two O atoms after intercalation. Therefore, the heterojunction with O2 molecule intercalation is labeled WSe2 / O2 / WS2. However, H2O molecule intercalation does not result in dissociation. Compared to the original heterojunction, both O2 and H2O molecule intercalation increase the interlayer spacing of the heterojunction.

[0126] Figure 3 The diagram shows the band arrangement and carrier separation and recombination of the van der Waals heterojunctions WSe2 / WS2, WSe2 / O2 / WS2, and WSe2 / H2O / WS2. It can be seen from the diagram that molecular intercalation does not change the band arrangement of the heterojunction – it is a type-II band arrangement. Carrier dynamics consists of three processes: (1) Electron transfer: Compared to the original heterojunction, O2 and H2O molecular intercalation introduces coupled states (gray bands), thus accelerating the electron transfer process. (2) Hole transfer: O2 molecular intercalation reduces coupled states, therefore hole transfer is the slowest. (3) Electron-hole recombination.

[0127] This invention modulates the photoelectric conversion properties of TMDC materials through the intercalation of ambient gas molecules (O2, H2O). Taking the WSe2 / WS2 heterojunction as an example, after intercalation of ambient gas molecules, the structure exhibits the following three advantages:

[0128] 1. Faster electron transfer than the original heterojunction. The unique interlayer confinement environment of the WSe2 / WS2 heterojunction effectively activates O2 molecules, causing them to spontaneously dissociate within the layers. Compared to the original heterojunction, the band gap decreases by 0.27 eV, but the type II band arrangement remains unchanged. Furthermore, the electron transfer time of the WSe2 / WS2 van der Waals heterojunction after O2 molecule intercalation is only half that of the original heterojunction.

[0129] 2. The H2O molecule intercalation in the WSe2 / WS2 heterojunction effectively extends the carrier lifetime. H2O molecule intercalation increases the interlayer distance of the heterojunction, and since the H2O molecules do not dissociate, the van der Waals band gap decreases by 0.18 eV, while the type-II band structure remains unchanged. The carrier lifetime of the H2O molecule intercalated heterojunction is 20 nanoseconds longer than that of the original heterojunction. Furthermore, H2O molecule intercalation promotes hole transfer, reducing the hole transfer time to one-third that of the original heterojunction, achieving robust spatial separation of electrons and holes. Therefore, robust charge spatial separation can be experimentally achieved through water molecule intercalation.

[0130] 3. It has the advantages of simplicity and scalability. Since the synthesis of stacked heterojunctions inevitably involves the intercalation of ambient gas molecules, the confined environment of the two-dimensional heterojunction can promote charge transfer at the interface, effectively activating molecules. These intercalated molecules, in turn, can regulate interlayer coupling. Therefore, ambient gas molecule intercalation is a simple yet powerful way to regulate the interlayer carrier dynamics of heterojunctions, and this discovery can be further extended to the entire TMDC heterojunction family.

[0131] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for predicting the effect of ambient gas molecular intercalation on the photoelectric conversion properties of van der Waals heterojunctions, characterized in that: The following steps are involved: (1) constructing a van der Waals heterojunction primitive cell by stacking a first monolayer two-dimensional material primitive cell and a second monolayer two-dimensional material primitive cell in a direction perpendicular to the surface of the two-dimensional material; expanding the van der Waals heterojunction primitive cell to obtain a van der Waals heterojunction supercell model; (2) intercalating ambient gas molecules at multiple non-equivalent sites in the van der Waals heterojunction supercell model, wherein the non-equivalent sites include one or more of interlayer bridge sites, interlayer vacancies and top sites, to obtain molecular intercalation van der Waals heterojunction models at different intercalation sites; structurally optimizing the intercalation van der Waals heterojunction models at different intercalation sites, performing energy statistics on the optimized intercalation van der Waals heterojunction models at different intercalation sites, and taking the intercalation van der Waals heterojunction model with the lowest energy as the ground state ambient gas molecule intercalation van der Waals heterojunction model; (3) performing differential charge density analysis on the ground state ambient gas molecule intercalation van der Waals heterojunction model to obtain the influence of different ambient gas molecule intercalation on the interlayer coupling of the van der Waals heterojunction; performing projected state density analysis on the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model to obtain the influence of different ambient gas molecule intercalation on the band gap and energy band arrangement of the van der Waals heterojunction; (4) using the NVE ensemble to simulate the molecular dynamics trajectory of the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model, respectively, and using the time-dependent density functional method to analyze the carrier dynamics of the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model, to obtain the influence of different ambient gas molecule intercalation on the carrier dynamics of the van der Waals heterojunction; the carrier dynamics includes the separation and recombination of electrons and holes; the separation of electrons and holes includes the transfer of electrons and the transfer of holes; in the process of recombination of electrons and holes, due to the existence of an obvious band gap, the quantum decoherence effect is considered to simulate the recombination process of electrons and holes; The method of using the NVE ensemble to simulate the molecular dynamics trajectory of the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model is as follows: simulating the molecular dynamics trajectory within 5000 steps under the NVE ensemble; the step length is 1 femtosecond; during the molecular dynamics trajectory simulation, the starting temperature and the ending temperature of the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model are both 300K; The method of using time-dependent density functional method to analyze carrier dynamics of van der Waals heterojunction supercell model is as follows: when analyzing the separation process of electrons and holes, 100 van der Waals heterojunction supercell models were selected, and 20,000 trajectories were sampled in the last 3 picoseconds of 5 picoseconds to obtain the energy level evolution with time and the change of electron energy with time; to analyze the lifetime of electrons, 50 van der Waals heterojunction supercell models were sampled 500 trajectories in 2 nanoseconds to obtain the layout change of electron energy with time; The method of carrier dynamics analysis of the ground-state ambient gas molecule intercalation van der Waals heterojunction model using the time-dependent density functional method is as follows: when analyzing the separation process of electrons and holes, 100 ground-state ambient gas molecule intercalation van der Waals heterojunction models are selected, and 20,000 trajectories are sampled in the last 2 picoseconds to obtain the time-varying energy level evolution and the time-varying electron energy evolution; The lifetime of photogenerated charge is obtained by fitting the e-exponential decay according to the relationship between the energy of electrons and time. (5) performing a non-adiabatic coupling average value analysis on the ground state ambient gas molecule intercalation van der Waals heterojunction model to obtain the influence of different ambient gas molecule intercalation on the non-adiabatic coupling average value of the van der Waals heterojunction; There is no time sequence limitation between step (3) and step (4).

2. The prediction method according to claim 1, characterized in that: The first single-layer two-dimensional material unit cell is a single-layer WSe2 unit cell, and the second single-layer two-dimensional material unit cell is a single-layer WS2 unit cell; the ambient gas molecules include O2 and / or gaseous H2O.

3. The prediction method according to claim 1, characterized in that: In the step (4), before performing the molecular dynamics trajectory simulation, the method further includes: preheating the van der Waals heterojunction supercell model and the ground state ambient gas molecule intercalation van der Waals heterojunction model respectively using the AIMD method; the preheating temperature is 300K.

4. The prediction method according to claim 1, characterized in that: The lattice length of the van der Waals heterojunction supercell> 5. The prediction method according to claim 1 or 4, characterized in that: The method for constructing the van der Waals heterojunction supercell model comprises the following steps: The first monolayer two-dimensional material primitive cell and the second monolayer two-dimensional material primitive cell are stacked by C7 to obtain a van der Waals heterojunction primitive cell; The van der Waals heterojunction primitive cell is expanded using periodic boundary conditions to obtain the van der Waals heterojunction supercell.

6. The prediction method according to claim 1, characterized in that: The energy statistics include the interlayer spacing of the intercalation van der Waals heterojunction model at different intercalation sites after statistical optimization, and the bond length and / or bond angle of the intercalated ambient gas molecules.

7. The prediction method according to claim 1, characterized in that: The structural optimization and the energy statistics in step (2) as well as the differential charge density analysis and the projected state density analysis in step (3) all adopt van der Waals correction.

8. The prediction method according to claim 1 or 7, characterized in that: The structural optimization and energy statistics in step (2) and the differential charge density analysis and projected state density analysis in step (3) are all performed using VASP6.3.0 software package; the cutoff energy is set to 500 eV, and the energy convergence standard is: the range of the model structure energy change is less than 10 - 5 eV, atomic force change <0.001

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