A patterned paper-cut structure for graphene conformal coating and a design method thereof

Abstract

The application discloses a patterned paper-cut structure for graphene conformal attachment and a design method thereof, and comprises the following steps: S1: adopting a full-atomic molecular dynamics method to simulate adhesion deformation of a graphene film on a target substrate surface with a non-zero Gaussian curvature; S2: extracting an atomic distribution of the adhesion attachment configuration according to a simulation result of step S1, and quantitatively calculating an adhesion conformal degree of the graphene film; S3: designing a plurality of paper-cut cutting patterns of the graphene film, repeating steps S1-S2 until the designed paper-cut cutting pattern reaches a target adhesion conformal degree, and taking the pattern as a final patterned paper-cut structure for graphene conformal attachment. The application can realize high conformal attachment of the graphene on a non-zero Gaussian curvature substrate such as a spherical surface without significantly damaging the overall continuity of the graphene, so that the adhesion and stability of the film and the substrate are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional nanofilm materials technology, and in particular to a patterned paper-cut structure for conformal bonding to graphene and its design method. Background Technology

[0002] In recent years, with the advancement of nanoscience and technology, micro- and nanomaterials, represented by graphene and other two-dimensional thin film materials, have shown broad application prospects in constructing high-performance functional or structural materials and micro- and nano-electromechanical systems. Due to its unique physical and mechanical properties compared to traditional functional materials, graphene has been explored for the design of advanced functional devices since its discovery, such as field emitters, nanoswitches, sensors, and flexible electronics. However, graphene films need to be adhered to a substrate to suppress the intrinsic wrinkles present in freestanding graphene films. Regardless of the device application, the interfacial characteristics between the graphene film and the supporting substrate will affect the performance of the functional device, and the adhesion morphology also has a significant impact on its electrical and mechanical properties.

[0003] In practice, the surfaces of the substrates supporting graphene films exhibit roughness at various scales. The adhesion and bonding of graphene films on rough substrates is an important interfacial mechanics problem. Current research on the influence of rough substrate surfaces on the adhesion and bonding behavior of graphene primarily focuses on substrates with unfoldable shapes such as one-dimensional unidirectional sinusoidal or rectangular grooves. However, in reality, substrate surfaces can possess non-unfoldable morphologies with non-Gaussian curvature, such as localized protrusions, and the substrate itself may also have a certain degree of non-Gaussian curvature, with roughness even comparable to the size of the graphene film.

[0004] Effectively attaching graphene films to target substrates with non-zero Gaussian curvature (such as spherical surfaces) has long been a key technical challenge. Traditional methods, including hot pressing, solution transfer, and soft template-assisted transfer, can achieve localized graphene attachment to some extent, but overall adhesion is poor, easily leading to wrinkling, warping, suspension, and cracking, which greatly limits the application of graphene in complex curved surface devices. Therefore, there is an urgent need for a tunable structural design strategy to improve the adhesion and conformal ability of graphene films to substrates with non-zero Gaussian curvature, thereby enhancing the overall stability and performance of the devices. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a patterned paper-cutting structure for conformal bonding with graphene and its design method.

[0006] The technical solution of the present invention is as follows: On the one hand, a design method for patterned paper-cut structures oriented towards graphene conformal bonding is provided, including the following steps: S1: The adhesion and deformation of graphene films on a target substrate surface with non-zero Gaussian curvature were simulated using all-atom molecular dynamics. S2: Extract the atomic distribution of the adhesion and bonding configuration based on the simulation results of step S1, and quantitatively calculate the degree of adhesion conformity of the graphene film. S3: Design various paper-cutting patterns for graphene films, repeat steps S1-S2 until the designed paper-cutting patterns achieve the target degree of conformal adhesion, and use this pattern as the final patterned paper-cutting structure for conformal bonding to graphene.

[0007] Preferably, in step S1, molecular dynamics simulation software is used for modeling and molecular dynamics simulation.

[0008] Preferably, the molecular dynamics simulation software used is LAMMPS software.

[0009] Preferably, in step S1, the target substrate with non-zero Gaussian curvature is a spherical silicon substrate.

[0010] Preferably, in step S2, the degree of adhesion conformity is calculated using the following formula: (1) In the formula: C represents the degree of conformal adhesion; n conform n represents the total number of carbon atoms in the conformal portion. initial This represents the total number of carbon atoms in the initial state of the graphene film. The total number of carbon atoms in the conformal portion is obtained through the following steps: First, the interatomic distance between carbon atoms in the graphene film and atoms in the substrate element is calculated using the following formula: (2) In the formula: d fg x represents the interatomic distance between carbon atoms f in the graphene film and atoms g in the substrate element; f y f z f Let f be the three-dimensional coordinates of a carbon atom f in the graphene film; x g y g z g Let g be the three-dimensional coordinates of the atom g, which is the base element. Then determine whether the interatomic spacing is less than or equal to the target interatomic spacing. If so, mark the carbon atoms of the graphene film as conformal portions. Finally, by iterating through all atoms, the total number of carbon atoms in the conformal portion is obtained.

[0011] Preferably, when the target substrate is a silicon substrate, the target atomic spacing is 6 Å.

[0012] Preferably, in step S3, when designing the paper-cutting pattern, if the target substrate with non-zero Gaussian curvature is a spherical substrate, a circular graphene film is used, and a seam is introduced along its radial direction, with a seam radial length of l. c The seam width is w, and the seams are cut M times at equal angles along the circumference. The rotation angle between adjacent seams is 360° / M.

[0013] Preferably, the seam width must meet the following conditions: (3) (4) In the formula: R is the change in film perimeter at equilibrium configuration; r is the radius of the circular graphene film; sub Let be the radius of the spherical base.

[0014] As a preferred option, the seam width w is taken as... .

[0015] On the other hand, a patterned paper-cutting structure for conformal bonding to graphene is also provided, which is designed using the design method for patterned paper-cutting structures for conformal bonding to graphene described in any one of the above-mentioned methods.

[0016] The beneficial effects of this invention are: This invention introduces a controllable two-dimensional slit pattern to achieve highly conformal adhesion of graphene to substrates with non-zero Gaussian curvature, such as spherical surfaces, without significantly compromising the overall continuity of graphene, thereby significantly improving the adhesion and stability of the film to the substrate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram illustrating the calculation process for the conformal adhesion degree of graphene films; Figure 2 This is a schematic diagram of the cutting design of a graphene film in a specific embodiment; Figure 3 This is a schematic diagram of the molecular dynamics model of a graphene film-spherical silicon substrate in a specific embodiment; Figure 4 This is a schematic diagram illustrating the energy changes and film configuration changes with molecular simulation time steps during the graphene film adhesion conformal process in a specific embodiment. Figure 5 This is a schematic diagram illustrating the variation of the conformal adhesion degree of an uncut graphene film on a spherical substrate with geometric dimensions in a specific embodiment; where A is the radius R of the spherical substrate. sub Equilibrium adhesion configurations of graphene films with different radii and a wavelength of 20 nm, where B is the radius R of the spherical substrate. sub The conformability C of graphene films at 10nm, 15nm, and 20nm varies with the radius ratio r / R sub Changes; Figure 6 This is a schematic diagram of the molecular dynamics model of paper-cutting graphene-spherical substrate in a specific embodiment; Figure 7 This is a schematic diagram showing the folds at different cutting times in a specific embodiment; Figure 8 This is a schematic diagram showing the adhesion state and conformal degree of paper-cut graphene under two different seam lengths and different cutting times in a specific embodiment; Figure 9 In a specific embodiment, the degree of conformal adhesion is related to the number of cuts M and the seam length l. c A schematic diagram illustrating the quantitative relationship between them. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0020] On one hand, this invention provides a design method for patterned paper-cut structures oriented towards graphene conformal bonding, comprising the following steps: S1: The adhesion and deformation of graphene films on a target substrate surface with non-zero Gaussian curvature were simulated using all-atom molecular dynamics.

[0021] In one specific embodiment, molecular dynamics simulation software is used for modeling and molecular dynamics simulation. Optionally, the molecular dynamics simulation software used is LAMMPS software.

[0022] In one specific embodiment, the target substrate with non-zero Gaussian curvature is a spherical silicon substrate. It should be noted that spherical non-zero Gaussian curvature structures are relatively common substrate structures. Besides this structure, other non-zero Gaussian curvature structures in the prior art, such as hyperboloids and concave-convex polyhedra, can also be applied to this invention.

[0023] S2: Extract the atomic distribution of the adhesion and bonding configuration based on the simulation results of step S1, and quantitatively calculate the degree of adhesion conformity of the graphene film.

[0024] In a specific embodiment, such as Figure 1 As shown, the degree of adhesion conformity is calculated using the following formula: (1) In the formula: C represents the degree of conformal adhesion; n conform n represents the total number of carbon atoms in the conformal portion. initial This represents the total number of carbon atoms in the initial state of the graphene film. The total number of carbon atoms in the conformal portion is obtained through the following steps: First, the interatomic distance between carbon atoms in the graphene film and atoms in the substrate element is calculated using the following formula: (2) In the formula: d fg x represents the interatomic distance between carbon atoms f in the graphene film and atoms g in the substrate element; f y f z f Let x be the three-dimensional coordinates of a carbon atom f in the graphene film; g y g z g Let g be the three-dimensional coordinates of the atom g, which is the base element. Then determine whether the interatomic spacing is less than or equal to the target interatomic spacing. If so, mark the carbon atoms of the graphene film as conformal portions. Finally, by iterating through all atoms, the total number of carbon atoms in the conformal portion is obtained.

[0025] In one specific embodiment, when the target substrate is a silicon substrate, the target atomic spacing is 6 Å.

[0026] S3: Design various paper-cutting patterns for graphene films, repeat steps S1-S2 until the designed paper-cutting patterns achieve the target degree of conformal adhesion, and use this pattern as the final patterned paper-cutting structure for conformal bonding to graphene.

[0027] Wrinkles reduce the conformality of graphene films, and their formation stems from geometric incompatibility. In cases of incomplete conformality, wrinkles typically appear at the film edges and extend radially. Paper-cutting technology is a subtractive method that achieves structural flexibility by cutting and hollowing out planar materials. This invention introduces paper-cutting design concepts into graphene films and uses molecular dynamics simulations to study how it enhances the conformal adhesion between graphene films and substrates with non-zero Gaussian curvature.

[0028] In a specific embodiment, such as Figure 2 As shown, when designing paper-cutting patterns, if the target substrate with non-zero Gaussian curvature is a spherical substrate, a circular graphene film is used, with a seam introduced radially along it, the radial length of which is l. c The seam width is w, and the seams are cut M times at equal angles along the circumference. The rotation angle between adjacent seams is 360° / M.

[0029] In one specific embodiment, the seam width must meet the following conditions: (3) (4) In the formula: R is the change in film perimeter at equilibrium configuration; r is the radius of the circular graphene film; sub Let be the radius of the spherical base.

[0030] When equation (3) holds true, the material damage to the graphene film is minimized; to minimize the material loss of the graphene film, the seam width w is taken as... .

[0031] When equation (3) is not satisfied, the edge portions of the graphene film will overlap after conformal cutting. Therefore, when designing paper cutting patterns, the seam width needs to meet the conditions of this equation.

[0032] On the other hand, the present invention also provides a patterned paper-cutting structure for conformal bonding to graphene, which is designed using the design method for a patterned paper-cutting structure for conformal bonding to graphene described in any one of the above-mentioned methods.

[0033] In one specific embodiment, taking a spherical silicon substrate as an example, the pattern of its graphene film is designed using the patterned paper-cut structure design method for conformal bonding of graphene described in this invention.

[0034] In this embodiment, the open-source molecular dynamics simulation software LAMMPS is used for modeling and molecular dynamics simulation, and OVITO is used for visualization.

[0035] The molecular dynamics model of graphene film-spherical substrate adhesion is attached. Figure 3As shown, graphene films and spherical silicon substrates were constructed using Atomsk. The silicon substrate has a lattice constant of 5.431 Å and a cubic unit cell with a diamond structure. The outer diameter of the silicon substrate was 20 nm. The graphene has a lattice constant of 0.246 nm, and each carbon atom forms covalent bonds with three surrounding carbon atoms.

[0036] Since the interaction between carbon and silicon atoms is very small when the distance between them exceeds 10 Å, the thickness of the substrate can be reduced without affecting the final result. This can be achieved by constructing a hollow spherical cap with a thickness greater than 10 Å, thereby reducing the computational cost.

[0037] The unit is set to a metal system. Aperiodic boundary conditions are set for the x, y, and z directions. The Verlet algorithm is used for time integration, with a time step of 1 femtosecond.

[0038] Carbon atoms in the graphene film interact via the AIREBO potential, while silicon atoms in the substrate interact via the TERSOFF potential. The interaction between the two types of atoms is described by the 12-6 Lennard-Jones potential function (zero equilibrium spacing of 4.0669 Å, potential well depth of 0.00428 eV), with a cutoff distance of 10.0 Å, which effectively characterizes the van der Waals interaction between graphene and the substrate.

[0039] The thin film maintains its x and y coordinates at its center of mass and can deform by moving in the z direction, while the substrate atoms remain fixed. Initially, the distance between the thin film and the substrate is set to 20 Å. Because the distance between the carbon atoms in the thin film and the silicon atoms in the substrate is greater than the cutoff distance, there is almost no interaction between the thin film and the substrate.

[0040] Using an NVT ensemble, the initial temperature of the system was set to 1 K. The graphene film was moved as a whole until it was within the Lennard-Jones potential cutoff distance, at which point it began to interact with the substrate atoms, while the substrate atoms remained in a rigid, fixed state. Due to the interaction between the film atoms and the substrate atoms, the graphene film moved towards the substrate until it reached an equilibrium configuration after sufficient relaxation. The sum of the graphene adhesion energy, tensile energy, and bending energy was given by the difference between the total energy after sufficient relaxation and the total energy in the initial state.

[0041] After the simulation is complete, the output data dump file is imported into the OVITO visualization software to observe the deformation process of the graphene film and its adhesion configuration after sufficient relaxation. Figure 4 As shown, the adhesive system reached a stable state after 200,000 steps.

[0042] The molecular dynamics simulation outputs a file containing the atom types, atom numbers, and atom coordinates in the equilibrium adhesion state. The atom types, atom numbers, and atom coordinates are then imported into MATLAB. For each carbon atom f in the graphene film, all substrate silicon atoms g are traversed, and the interatomic spacing d... fg If the carbon atom label of the graphene film is ≤6 Å, then the carbon atom label of the graphene film is stored in the conformal portion. The adhesion conformity of the graphene film is calculated by equation (1). The adhesion conformity of the uncut graphene film on the spherical substrate varies with the geometric dimensions as follows: Figure 5 As shown.

[0043] from Figure 5 It can be seen that when the radius (r) of the graphene film is equal to the radius (R) of the spherical substrate... sub The ratio of r / R sub When the radius is less than 0.4, the graphene film is in the fully conformal stage. As the radius of the graphene film increases, wrinkles form, causing the conformity degree C to continuously decrease. The conformity degree C increases with r / R. sub The trend is roughly linearly decreasing. When the graphene radius is smaller than the substrate radius, the conformality of the film is greater than 75%. A paper-cutting pattern is designed using a graphene film radius of r = 14 nm, and the seam width w is taken as... .

[0044] Molecular dynamics model of paper-cut graphene-spherical substrate as follows Figure 6 As shown, the folds appear as follows with different cutting counts. Figure 7 As shown, the adhesion state and conformity results for different cutting times and different radial lengths are as follows: Figure 8 As shown, the quantitative relationship between the degree of conformal adhesion and the number of cuts M and the seam length lc is as follows: Figure 9 As shown.

[0045] from Figure 7 It can be seen that the degree of conformity increases with the increase of the number of cuttings M and the seam length l. c As the length increases, the wrinkles also increase. If the number of cuts is too small, wrinkles will appear not only at the cut but also at the intact edges; when the cut length is long enough and the number of cuts is large enough, the wrinkles in the graphene film will be eliminated.

[0046] from Figure 8 It can be seen that for a tailor's length of l c Graphene cut to 8nm diameter can achieve complete conformality when cut twice or more. When the seam length is l... c At a thickness of 4nm, all graphene cuts exhibited wrinkles, but the degree of conformal adhesion increased with the number of cuts. When uncut, the conformal degree of the graphene film was 86.53%, and the seam length l cThe conformal degree of the paper-cut graphene with a diameter of 4nm and a cutting number of M=2 exceeds 90%. When M=8, the conformal degree reaches approximately 97%.

[0047] Figure 9 In the diagram, the blue line represents the contour line indicating a conformity of 99.5% derived from data fitting. When the conformity is greater than or equal to 99.5%, graphene is considered to be completely conformal to the spherical substrate. Figure 9 It can be seen that the more cuts made and the longer the seam length, the higher the degree of conformal adhesion. Through... Figure 9 This can guide the design of paper-cut patterns to achieve a greater degree of conformal adhesion. To ensure complete conformal adhesion of the graphene film to a spherical substrate, the cut length must be at least 7 nm. With a cut length of 8 nm, complete conformal adhesion can be achieved with 5 cuts, eliminating the need for 6 or even 8 cuts. Further constraint planning methods can consider reducing material loss and the number of cuts to achieve the target degree of conformal adhesion.

[0048] It should be noted that the above-described embodiments of the present invention are merely one preferred embodiment, and the length and width of the seams used are only a general seam design concept. The design philosophy and simulation method are also applicable to other forms of paper-cutting structures, such as grid-like and scale-like two-dimensional paper-cutting patterns. These patterns will also help improve the conformal capability of graphene on non-zero Gaussian curvature substrates.

[0049] The molecular dynamics simulation framework and index system for quantitatively calculating the degree of adhesion conformity of this invention have good versatility and reference value, and can provide theoretical support and methodological guidance for the paper-cutting design and performance optimization of other two-dimensional nanomaterials.

[0050] In practice, graphene can be cut according to the designed paper-cutting pattern using techniques such as laser etching and focused ion beam etching. Alternatively, a path of first cutting and patterning the graphene before transferring it can be adopted to achieve overall paper-cutting pattern transfer and conformal attachment.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A design method for patterned paper-cut structures oriented towards graphene conformal bonding, characterized in that, Includes the following steps: S1: The adhesion and deformation of graphene films on a target substrate surface with non-zero Gaussian curvature were simulated using all-atom molecular dynamics. S2: Extract the atomic distribution of the adhesion and bonding configuration based on the simulation results of step S1, and quantitatively calculate the degree of adhesion conformity of the graphene film; the degree of adhesion conformity is calculated using the following formula: （1） In the formula: C represents the degree of conformal adhesion; n conform n represents the total number of carbon atoms in the conformal portion. initial This represents the total number of carbon atoms in the initial state of the graphene film. The total number of carbon atoms in the conformal portion is obtained through the following steps: First, the interatomic distance between carbon atoms in the graphene film and atoms in the substrate element is calculated using the following formula: （2） In the formula: d fg x represents the interatomic distance between carbon atoms f in the graphene film and atoms g in the substrate element; f y f z f x represents the three-dimensional coordinates of a carbon atom f in the graphene film; g y g z g Let g be the three-dimensional coordinates of the atom g, which is the base element. Then determine whether the interatomic spacing is less than or equal to the target interatomic spacing. If so, mark the carbon atoms of the graphene film as conformal portions. Finally, by iterating through all atoms, the total number of carbon atoms in the conformal portion is obtained; S3: Design various paper-cutting patterns for graphene films, repeat steps S1-S2 until the designed paper-cutting patterns achieve the target degree of conformal adhesion, and use this pattern as the final patterned paper-cutting structure for conformal bonding to graphene.

2. The design method for patterned paper-cut structures oriented towards graphene conformal bonding according to claim 1, characterized in that, In step S1, molecular dynamics simulation software is used for modeling and molecular dynamics simulation.

3. The design method for patterned paper-cut structures oriented towards graphene conformal bonding according to claim 2, characterized in that, The molecular dynamics simulation software used is LAMMPS.

4. The design method for patterned paper-cutting structures oriented towards graphene conformal bonding according to claim 1, characterized in that, In step S1, the target substrate with non-zero Gaussian curvature is a spherical silicon substrate.

5. The design method for patterned paper-cut structures oriented towards graphene conformal bonding according to claim 1, characterized in that, When the target substrate is a silicon substrate, the target atomic spacing is 6 Å.

6. The design method for patterned paper-cut structures oriented towards graphene conformal bonding according to claim 1, characterized in that, In step S3, when designing the paper-cutting pattern, if the target substrate with non-zero Gaussian curvature is a spherical substrate, a circular graphene film is used, and a seam is introduced along its radial direction, with a seam radial length of l. c The seam width is w, and the seams are cut M times at equal angles along the circumference. The rotation angle between adjacent seams is 360° / M.

7. The design method for patterned paper-cutting structures oriented towards graphene conformal bonding according to claim 6, characterized in that, The seam width must meet the following conditions: （3） （4） In the formula: R is the change in film perimeter at equilibrium configuration; r is the radius of the circular graphene film; sub Let be the radius of the spherical base.

8. The design method for patterned paper-cut structures oriented towards graphene conformal bonding according to claim 7, characterized in that, The width of the tailor, w, is taken as .

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