A flexible packaging film based on two-dimensional material and a preparation method and application thereof

Abstract

This invention relates to the field of optoelectronic packaging, specifically to a flexible packaging film based on two-dimensional materials, its preparation method, and its applications. The packaging film structure comprises a first protective layer, a two-dimensional material layer, a transfer support layer, a heat-resistant support layer, an adhesion layer, and a second protective layer, stacked sequentially. First, a two-dimensional material layer is grown on a metal foil substrate. Then, a transfer support layer is fabricated on the surface of the two-dimensional material layer. After removing the metal foil substrate, the two-dimensional material layer / transfer support layer is transferred to the surface of the first protective layer. Finally, a heat-resistant support layer, an adhesion layer, and a second protective layer are fabricated on the surface of the transfer support layer. A molding method is used to remove interlayer gases and increase interlayer interactions. This invention maintains the integrity of the two-dimensional material layer structure, requiring only 1-3 layers of two-dimensional material to achieve high water vapor and oxygen barrier properties in the packaging film. It also possesses good flexibility and ease of use, allowing for simple application to encapsulate devices and meeting the requirements for device bending and winding.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic packaging, specifically a flexible packaging film based on two-dimensional materials, its preparation method, and its application. Background Technology

[0002] Flexible optoelectronic devices, including organic transistors, organic solar cells, and organic light-emitting diodes, have become an important trend in future device development due to their unique flexibility, portability, and thinness, and have broad application prospects. However, device stability and lifespan are among the biggest challenges restricting their development. Among these challenges, water vapor and oxygen corrosion in the environment are the main factors causing a sharp decline in device performance. Therefore, encapsulating the devices with encapsulation layers that block the diffusion of water vapor and other gases is key to extending the lifespan of flexible optoelectronic devices, maintaining their long-term stability, and ultimately achieving industrialization.

[0003] Traditional encapsulation methods use resin adhesive to attach a rigid glass cover to the target area, providing a barrier against water and oxygen. However, this rigid encapsulation cannot meet the encapsulation requirements of flexible optoelectronics. Currently, protective layers with a hybrid inorganic and organic structure are replacing the cover encapsulation, bringing a breakthrough to flexible optoelectronics technology. However, the methods used are complex, and the inherent brittleness of inorganic thin film materials, as well as the elastic mismatch between the organic and inorganic layers, lead to film delamination under external stress and strain, resulting in unsatisfactory flexible encapsulation performance.

[0004] Two-dimensional materials such as graphene and boron nitride have dense structures, making them ideal physical barrier layers. Their strong covalent bonds within the layers provide good elasticity, thus forming sandwich structures with organic layers promises excellent flexible encapsulation effects. Currently, large-area, high-quality two-dimensional material films are mainly grown on metal foil substrates using methods such as chemical vapor deposition (CVD). However, this process often requires removing the metal foil substrate, transferring the two-dimensional material film to a corresponding protective layer, and then removing the transfer support layer. This process is complex and costly. More importantly, because the support layer often interacts strongly with the two-dimensional material, its removal can easily lead to defects and cracks in the two-dimensional material film, significantly affecting the barrier performance of the encapsulation film. Furthermore, traditional cover plate encapsulation often uses edge sealing processes, using epoxy resin UV-curable adhesive to bond the cover plate to the substrate. However, epoxy resin UV-curable adhesive is a major channel for the permeation of gases such as water and oxygen, affecting the barrier performance of the encapsulation film. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible encapsulation film based on two-dimensional materials, its preparation method, and its applications. Utilizing the excellent barrier properties of two-dimensional material films and the excellent adhesion of cured adhesive solutions such as polydimethylsiloxane, phenolic resin, and polyurethane, a flexible encapsulation film with the structure of a first protective layer / two-dimensional material layer / transfer support layer / heat-resistant support layer / adhesion layer / second protective layer is designed. Its structure is simple, possesses good flexibility, and can meet the bending and winding requirements of devices. Moreover, it is convenient to use; after peeling off the second protective layer, it can be directly attached to the surface of optoelectronic devices for encapsulation. Unlike edge sealing processes, this encapsulation film completely covers the area of ​​the device requiring encapsulation and can achieve roll-to-roll encapsulation. The preparation method of this encapsulation film retains the transfer support layer, which not only enhances the mechanical properties of the encapsulation film but also minimizes damage to the two-dimensional material during the removal of the transfer support layer. Therefore, only 1-3 layers of two-dimensional materials are needed to give the encapsulation film high water vapor and oxygen barrier properties, making it a promising candidate for application in the optoelectronic packaging field.

[0006] The technical solution of this invention is:

[0007] A flexible encapsulation film based on two-dimensional materials is provided. The encapsulation film structure consists of a first protective layer, a two-dimensional material layer, a transfer support layer, a heat-resistant support layer, an adhesion layer, and a second protective layer stacked sequentially.

[0008] The flexible encapsulation film based on two-dimensional materials has two-dimensional material layers that are one or more of graphene, boron nitride, transition metal chalcogenides, MoSi2N4, and WSi2N4 with layered structures, and the number of layers is 1 to 3.

[0009] The flexible encapsulation film based on two-dimensional materials has a first protective layer or a second protective layer made of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, or polypropylene. The thickness of the first protective layer is 20–300 μm, and the thickness of the second protective layer is 10–50 μm.

[0010] The flexible encapsulation film based on two-dimensional materials has a transfer support layer consisting of one or more layers of polymethyl methacrylate, rosin, paraffin wax, polycarbonate, polypropylene carbonate, and polyimide, with a thickness of 20 nm to 300 nm; and a heat-resistant support layer consisting of one or more layers of polyimide, polyphenylene sulfide, and polyetheretherketone, with a thickness of 100 nm to 40 μm.

[0011] The flexible encapsulation film based on two-dimensional materials has an adhesion layer made of polydimethylsiloxane, phenolic resin, or polyurethane, with a thickness of 100 nm to 40 μm.

[0012] The method for preparing a flexible encapsulation film based on two-dimensional materials involves first growing a two-dimensional material layer on a metal foil substrate, then fabricating a transfer support layer on the surface of the two-dimensional material layer, removing the metal foil substrate, transferring the two-dimensional material layer / transfer support layer to the surface of a first protective layer, and finally fabricating a heat-resistant support layer, an adhesive layer, and a second protective layer on the surface of the transfer support layer. The gas between the layers is removed and the interlayer interaction is increased by molding.

[0013] The method for preparing a flexible encapsulation film based on two-dimensional materials involves growing a metal foil substrate of Cu, Ni, Au, Pt or their alloys with a thickness of 10–50 μm; growing 1–3 layers of two-dimensional materials; and removing the metal foil substrate by chemical etching or electrochemical stripping after fabricating a transfer support layer on the surface of the two-dimensional material layers.

[0014] The method for preparing a flexible encapsulation film based on two-dimensional materials involves removing the metal foil substrate and then attaching a single-layer two-dimensional material layer / transfer support layer as a composite transfer support layer to the surface of the two-dimensional material layer grown on the metal foil substrate. The metal foil removal step is repeated to obtain a two- to three-layer two-dimensional material layer / transfer support layer structure with one or more stacked structures.

[0015] The method for preparing the flexible encapsulation film based on two-dimensional materials involves expelling gas between layers and increasing interlayer interaction through molding, with a pressure of 0.5–50 MPa and a temperature of 60–120 °C.

[0016] The application of the flexible encapsulation film based on two-dimensional materials has good flexibility. It can be used to encapsulate optical / electronic devices in areas that need to be blocked by applying the film, while also satisfying the bending and winding properties of the devices.

[0017] The design concept of this invention is:

[0018] Two-dimensional materials such as graphene, boron nitride, transition metal chalcogenides, MoSi2N4, and WSi2N4 have dense structures, making them ideal physical barrier layers. Their strong covalent bonds within the layers provide good elasticity, and forming a sandwich structure with organic layers avoids elastic mismatch issues. Therefore, forming a sandwich structure between two-dimensional material layers and organic layers can yield flexible encapsulation films with excellent water and oxygen barrier properties. Furthermore, utilizing the excellent adhesion of polydimethylsiloxane, phenolic resin, and polyurethane, the encapsulation film can be directly applied to the area to be encapsulated in optoelectronic devices to provide water and oxygen barrier functions. This process is convenient and solves the problem of complex edge sealing processes in traditional cover plate encapsulation, preventing the penetration of water, oxygen, and other gases through the epoxy resin UV-cured adhesive.

[0019] The key to fabricating encapsulation films based on two-dimensional materials is the ability to sandwich two-dimensional material films between organic films. Currently, obtaining large-area, high-quality two-dimensional material films mainly involves growing them on metal foil substrates using methods such as CVD, which requires transferring them to an organic layer. During the transfer process, a transfer support layer needs to be fabricated on the surface, the metal foil substrate removed, and the transfer completed before the transfer to the corresponding organic layer, after which the transfer support layer must also be removed. This process is complex, costly, and difficult to scale up. More importantly, this process easily leads to defects and cracks in the two-dimensional material film. In particular, the strong interaction between the transfer support layer and the two-dimensional material means that the removal process can tear the two-dimensional material film and create defects, significantly affecting the barrier properties of the encapsulation film. This invention directly utilizes the transfer support layer as a support layer for the encapsulation film, avoiding the removal process of the transfer support layer, ensuring the structural integrity of the two-dimensional material film, and requiring only 1-3 layers of two-dimensional material to achieve high water vapor and oxygen barrier properties in the encapsulation film.

[0020] The advantages and beneficial effects of this invention are:

[0021] 1. This invention utilizes the high water and oxygen barrier properties of two-dimensional materials such as graphene and their good elasticity to form a sandwich structure with organic materials. It also utilizes the excellent adhesion of polydimethylsiloxane, phenolic resin, and polyurethane to design a flexible encapsulation film with the structure of a first protective layer / two-dimensional material layer / transfer support layer / heat-resistant support layer / adhesion layer / second protective layer. The structure is simple and has good flexibility, which solves the problem of elastic mismatch in the process of bending and winding when inorganic and organic layers form a sandwich structure, and can meet the bending and winding requirements of the device.

[0022] 2. This invention directly uses the transfer support layer as a support layer of the encapsulation film, avoiding the removal process of the transfer support layer and ensuring the integrity of the two-dimensional material film. Therefore, only 1 to 3 layers of two-dimensional material are needed to have high water vapor and oxygen barrier properties.

[0023] 3. The encapsulation film of the present invention is easy to use. After peeling off the second protective layer, it can be directly applied to the surface of optoelectronic devices for encapsulation. This avoids the complexity of traditional cover sealing processes and prevents the penetration of gases such as water and oxygen through the epoxy resin UV curing adhesive. It can also achieve roll-to-roll encapsulation, is easy to scale up, and has good market application scenarios. Attached Figure Description

[0024] Figure 1 This diagram shows the structure of the encapsulation film based on two-dimensional materials according to the present invention. In the figure, 1 is the first protective layer; 2 is the two-dimensional material layer; 3 is the transfer support layer; 4 is the heat-resistant support layer; 5 is the adhesion layer; and 6 is the second protective layer.

[0025] Figure 2 This is a schematic diagram of the fabrication process of an encapsulation film based on two-dimensional materials.

[0026] Figure 3 These are photographs of the encapsulation film based on monolayer graphene in Example 1. (a) shows the spread state, and (b) shows the bent state. Detailed Implementation

[0027] like Figure 1 As shown, the encapsulation film structure of the present invention consists of a first protective layer 1, a two-dimensional material layer 2, a transfer support layer 3, a heat-resistant support layer 4, an adhesion layer 5, and a second protective layer 6 stacked sequentially.

[0028] like Figure 2 As shown, the specific preparation process of the encapsulation film based on two-dimensional materials in this invention is as follows:

[0029] First, one to three layers of two-dimensional materials with layered structures, such as graphene, boron nitride, transition metal chalcogenides, MoSi₂N₄, or WSi₂N₄, are grown on a metal foil substrate of Cu, Ni, Au, Pt, or their alloys, with a thickness of 10–50 μm. Then, one or more layers of polymethyl methacrylate (PMMA), rosin, paraffin wax, polycarbonate (PC), polypropylene carbonate (PPC), or polyimide (PI) are fabricated on the surface of the two-dimensional material layer as a transfer support layer, with a thickness of 20 nm–300 nm. Subsequently, the metal foil substrate is removed by chemical etching or electrochemical stripping. If necessary, a single-layer two-dimensional material / transfer support layer can be further deposited as a composite transfer support layer on the surface of the two-dimensional material layer grown on the metal foil substrate. Repeating the metal foil substrate removal step yields two to three layers of two-dimensional material / transfer support layer structures with one or more stacked structures. Finally, the two-dimensional material / transfer support layer is transferred to the surface of a first protective layer with a thickness of 20–300 μm. Subsequently, one or more layers of polyimide (PI), polyphenylene sulfide (PPS), or polyether ether ketone (PEEK) are fabricated on the surface of the transfer support layer as a heat-resistant support layer, with a thickness of 100 nm to 40 μm. Further, an adhesion layer with a thickness of 100 nm to 40 μm and a second protective layer with a thickness of 10 μm to 50 μm are sequentially fabricated on the surface of the heat-resistant support layer. Finally, moisture and gas between the layers are removed by molding at a pressure of 0.5–50 MPa and a temperature of 60–120 °C.

[0030] The adhesive layer is made of polydimethylsiloxane (PDMS), phenolic resin, or polyurethane, and is stable in high-temperature, acidic, and alkaline environments. Both the first and second protective layers are made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), or polypropylene (PP).

[0031] The resulting encapsulation film has high flexibility and is easy to use. By simply peeling off the second protective layer, optoelectronic devices can be encapsulated in areas requiring water and oxygen barrier by simple application, and the device can be bent and wound.

[0032] The present invention will now be described in further detail with reference to the embodiments.

[0033] Example 1

[0034] The encapsulation film structure obtained in this embodiment consists of a first protective layer (PEN), a graphene layer, a PMMA transfer support layer, a PI heat-resistant support layer, a PDMS adhesion layer, and a second protective layer (PEN) stacked sequentially. The specific preparation process is as follows: First, a graphene layer is grown on a 25 μm thick Cu foil substrate; then, a 100 nm thick PMMA transfer support layer is fabricated on the graphene layer surface. The Cu foil substrate is then removed using chemical etching. Next, the graphene layer / PMMA transfer support layer is transferred to the surface of the first protective layer (PEN), which has a thickness of 250 μm. Then, a 25 μm thick PI heat-resistant support layer, a 30 μm thick PDMS adhesion layer, and a 20 μm thick second protective layer (PEN) are sequentially fabricated on the PMMA transfer support layer surface. Finally, interlayer moisture and gas are removed by molding at a pressure of 2 MPa and a temperature of 60 °C.

[0035] The resulting encapsulation film is as follows Figure 3 As shown, it exhibits high flexibility, with a water vapor permeability of 2.7 × 10⁻⁶ under conditions of 100% relative humidity and 85℃. -4 gm -2 day -1 After removing the second protective layer, it is applied to the surface of the perovskite solar cell device and placed in an acidic aqueous solution with a pH of 1. After heating at 85°C for 60 hours, the efficiency remains unchanged.

[0036] Example 2

[0037] In this embodiment, the encapsulation film structure consists of a first protective layer (PET), a boron nitride layer, a PI layer, a PDMS adhesion layer, and a second protective layer (PET) stacked sequentially. The PI layer serves as both a transfer support layer and a heat-resistant support layer. The specific fabrication process is as follows: First, a boron nitride layer is grown on a 30 μm thick Cu foil substrate. Then, a 300 nm thick PI layer is fabricated on the surface of the boron nitride layer. The Cu foil substrate is then removed using chemical etching. Next, the boron nitride / PI layer is transferred to the surface of the first protective layer (PET), which has a thickness of 200 μm. Subsequently, a 23 μm thick PI layer, a 30 μm thick PDMS adhesion layer, and a 20 μm thick second protective layer (PET) are fabricated on the surface of the PI layer. Finally, moisture and gas between the layers are removed by molding at a pressure of 5 MPa and a temperature of 80 °C.

[0038] The resulting encapsulation film exhibits high flexibility, with a water vapor permeability of 5.89 × 10⁻⁶ under conditions of 100% relative humidity and 85℃. -4 gm -2 day -1 After removing the second protective layer, the OLED device was encapsulated and left to stand in the air for 8 hours. Its external quantum efficiency (EQE) remained unchanged at 24.1%.

[0039] Example 3

[0040] In this embodiment, the encapsulation film structure consists of a first protective layer (PET), a bilayer graphene layer, a PPC transfer support layer, a PPS heat-resistant support layer, a phenolic resin adhesive layer, and a second protective layer (PC), stacked sequentially. The specific preparation process is as follows: First, a graphene layer is grown on a 15μm thick Cu foil substrate. Then, a 250nm thick PPC layer is fabricated on the surface of the graphene layer as a transfer support layer. The Cu foil substrate is then removed using chemical etching. Next, a graphene / PPC transfer support layer is applied as a composite transfer support layer to the surface of the graphene layer grown on the 15μm thick Cu foil substrate. The Cu foil substrate is again removed using chemical etching to obtain the bilayer graphene / PPC transfer support layer, which is then transferred to the surface of the first protective layer (PET), which has a thickness of 250μm. Subsequently, a 25μm thick PPS heat-resistant support layer, a 10μm thick phenolic resin adhesive layer, and a 30μm thick second protective layer (PC) are sequentially fabricated on the surface of the PPC transfer support layer. Finally, moisture and gas between layers are removed by molding at a pressure of 8 MPa and a temperature of 60°C.

[0041] When an OLED device is encapsulated using this structure, its EQE remains unchanged at 24.2% after being left to stand in air for 12 hours.

[0042] Example 4

[0043] The encapsulation film structure obtained in this embodiment consists of a first protective layer (PC), a MoSi2N4 layer, a graphene layer, a PC transfer support layer, a PI heat-resistant support layer, a phenolic resin adhesive layer, and a second protective layer (PC) stacked sequentially. The specific preparation process is as follows: First, a graphene layer and a MoSi2N4 layer with thicknesses of 25 μm and 20 μm are grown on Cu foil substrates, respectively. Then, a 200 nm thick PC layer is fabricated on the surface of the graphene layer as a transfer support layer, followed by the removal of the Cu foil substrate using chemical etching. Next, a graphene / PC transfer support layer is attached as a composite transfer support layer to the surface of the MoSi2N4 layer grown on the Cu foil substrate. The Cu foil substrate is again removed by chemical etching and transferred to the surface of the 100 μm thick first protective layer (PC). Finally, a 25 μm thick PI heat-resistant support layer, a 30 μm thick phenolic resin adhesive layer, and a 30 μm thick PC second protective layer are sequentially fabricated on the surface of the PC transfer support layer. Finally, moisture and gas between layers are removed by molding at a pressure of 20 MPa and a temperature of 80°C.

[0044] Under conditions of 100% relative humidity and 85℃, the water vapor transmission rate is 8.23×10⁻⁶. -4 gm -2 day -1 When organic field-effect transistors are encapsulated using this structure, their carrier mobility remains at 1.41 cm⁻¹ after being left to stand in air for 24 hours. 2 V -1 s -1 constant.

[0045] Example 5

[0046] The encapsulation film structure obtained in this embodiment consists of a first protective layer (PP), a transition metal chalcogenide (WS2) layer, a rosin and PMMA transfer support layer, a PEEK and PI heat-resistant support layer, a polyurethane adhesive layer, and a second protective layer (PET) stacked sequentially. The specific preparation process is as follows: First, WS2 is grown on a 40 μm thick Au foil substrate, with one layer. Then, a 40 nm thick rosin transfer support layer and a 200 nm thick PMMA transfer support layer are fabricated on the surface of the WS2 layer. Subsequently, the Au foil substrate is separated from the WS2 layer / rosin / PMMA transfer support layer by electrochemical peeling. The WS2 layer / rosin / PMMA transfer support layer is then transferred to the 150 μm thick surface of the first protective layer (PP). Afterward, 30 μm and 10 μm thick PEEK and PI heat-resistant support layers, a 30 μm thick polyurethane adhesive layer, and a 20 μm thick second protective layer (PET) are fabricated on the surface of the PMMA transfer support layer. Finally, moisture and gas between layers are removed by molding at a pressure of 30 MPa and a temperature of 60°C.

[0047] Under conditions of 100% relative humidity and 85℃, the water vapor permeability of the encapsulation film is 2.61×10⁻⁶. -3 gm - 2 day -1 When organic solar cell devices are encapsulated using this structure and left to stand in air for 48 hours, the photoelectric conversion efficiency remains unchanged at 12.6%.

[0048] Example 6

[0049] The difference from Example 1 is that the transfer support layer used in this example consists of a 200 nm thick rosin layer and a 100 nm thick PMMA layer sequentially fabricated on a two-dimensional material layer. The two-dimensional material used is bilayer graphene grown on a 40 μm thick Cu-Ni alloy foil substrate (in this example, the Cu-Ni alloy grade is C26000). The substrate removal method used is electrochemical exfoliation. Under conditions of 100% relative humidity and 85°C, the water vapor permeability of the encapsulation film is 3.22 × 10⁻⁶. -3 gm -2 day -1 When an OLED device is encapsulated with this structure, its EQE remains unchanged at 23.1% after being left to stand in air for 48 hours.

[0050] Example 7

[0051] The difference from Example 1 is that the transfer support layer used in this example consists of a 200 nm thick paraffin layer and a 100 nm thick PMMA layer sequentially fabricated on a two-dimensional material layer. The two-dimensional material used is WSi2N4 grown on a 30 μm thick Pt foil substrate. The substrate removal method used is electrochemical stripping. The resulting encapsulation film has a water vapor permeability of 6.71 × 10⁻⁶ under conditions of 100% relative humidity and 85°C. -3 gm -2 day -1 When organic solar cells are encapsulated with this structured encapsulation film, the fill factor of the organic solar cells remains unchanged at 0.63 after heating at 85°C for 30 minutes.

[0052] Example 8

[0053] In this embodiment, the encapsulation film structure consists of a first protective layer (PET), a graphene layer, a boron nitride layer, a WSi2N4 layer, a PMMA transfer support layer, a PI heat-resistant support layer, a phenolic resin adhesive layer, and a second protective layer (PP), stacked sequentially. The specific preparation process is as follows: First, a WSi2N4 layer is grown on a 25μm thick Pt foil substrate, with one layer. Then, a 250nm PMMA transfer support layer is prepared on the surface of the WSi2N4 layer. The Pt foil substrate is then separated from the WSi2N4 layer / PMMA transfer support layer using an electrochemical stripping method. Next, the WSi2N4 layer / PMMA transfer support layer is used as a composite transfer support layer and adhered to the surface of a boron nitride layer grown on a 30μm thick Cu foil substrate. The Cu foil substrate is then removed using a chemical etching method. A boron nitride / WSi2N4 / PMMA transfer support layer was then deposited as a composite transfer support layer onto a graphene layer grown on a 25 μm thick Cu foil substrate. The Cu foil substrate was removed using chemical etching, and the graphene / boron nitride / WSi2N4 / PMMA transfer support layer was transferred to a 200 μm thick PET surface. A 30 μm thick PI layer, a 30 μm thick phenolic resin adhesive layer, and a 20 μm thick second protective PP layer were then fabricated on the PMMA transfer support layer surface. Finally, interlayer moisture and gas were removed using molding at 20 MPa and 80 °C.

[0054] The perovskite solar cell encapsulated by this packaging structure maintains its efficiency unchanged after 200 hours at 30°C and 45% relative humidity.

[0055] The results show that the flexible encapsulation film based on two-dimensional materials of the present invention maintains the integrity of the two-dimensional material layer structure during the preparation process, requiring only 1 to 3 layers of two-dimensional materials to effectively block water vapor and oxygen. Specifically, the first protective layer is located on the outermost side during use, protecting the two-dimensional material layer and other functional layers; the transfer support layer ensures the integrity of the two-dimensional material transfer process; the heat-resistant support layer further enhances the support effect and provides heat insulation; the adhesion layer maintains stability in high-temperature, acidic, and alkaline environments; and the second protective layer prevents contamination of the adhesion layer surface, and is removed during use. Simultaneously, the encapsulation film exhibits good flexibility and ease of use, allowing for simple application to encapsulate devices, and also meets the requirements for device bending and winding.

Claims

1. A flexible encapsulation film based on two-dimensional materials, characterized in that, The encapsulation film structure consists of a first protective layer, a two-dimensional material layer, a transfer support layer, a heat-resistant support layer, an adhesive layer, and a second protective layer stacked sequentially.

2. The flexible encapsulation film based on two-dimensional materials according to claim 1, characterized in that, The two-dimensional material layer is a stacked structure of one or more of the following: graphene, boron nitride, transition metal chalcogenides, MoSi2N4, and WSi2N4, with the number of layers ranging from 1 to 3.

3. The flexible encapsulation film based on two-dimensional materials according to claim 1, characterized in that, The material of the first or second protective layer is polyethylene terephthalate, polyethylene naphthalate, polycarbonate or polypropylene, the thickness of the first protective layer is 20 to 300 μm, and the thickness of the second protective layer is 10 to 50 μm.

4. The flexible encapsulation film based on two-dimensional materials according to claim 1, characterized in that, The transfer support layer consists of one or more layers of polymethyl methacrylate, rosin, paraffin, polycarbonate, polypropylene carbonate, and polyimide, with a thickness of 20 nm to 300 nm; the heat-resistant support layer consists of one or more layers of polyimide, polyphenylene sulfide, and polyether ether ketone, with a thickness of 100 nm to 40 μm.

5. The flexible encapsulation film based on two-dimensional materials according to claim 1, characterized in that, The adhesive layer is made of polydimethylsiloxane, phenolic resin or polyurethane, and has a thickness of 100 nm to 40 μm.

6. A method for preparing a flexible encapsulation film based on two-dimensional materials as described in any one of claims 1 to 5, characterized in that, First, a two-dimensional material layer is grown on a metal foil substrate. Then, a transfer support layer is fabricated on the surface of the two-dimensional material layer. After removing the metal foil substrate, the two-dimensional material layer / transfer support layer is transferred to the surface of the first protective layer. Finally, a heat-resistant support layer, an adhesive layer, and a second protective layer are fabricated on the surface of the transfer support layer. The interlayer gas is removed and the interlayer interaction is increased by molding.

7. The method for preparing a flexible encapsulation film based on two-dimensional materials according to claim 6, characterized in that, The metal foil substrate on which the two-dimensional material layer is grown is Cu, Ni, Au, Pt or their alloy, with a thickness of 10 to 50 μm; the number of two-dimensional material layers is 1 to 3; after a transfer support layer is fabricated on the surface of the two-dimensional material layer, the metal foil substrate is removed by chemical etching or electrochemical stripping.

8. The method for preparing a flexible encapsulation film based on two-dimensional materials according to claim 6, characterized in that, After removing the metal foil substrate, a single-layer two-dimensional material layer / transfer support layer is further attached to the surface of the two-dimensional material layer grown on the metal foil substrate as a composite transfer support layer. The metal foil removal step is repeated to obtain a two-dimensional material layer / transfer support layer structure with one or more stacked structures of 2 to 3 layers.

9. The method for preparing a flexible encapsulation film based on two-dimensional materials according to claim 6, characterized in that, The gas between layers is removed and the interaction between layers is increased by molding, with a pressure of 0.5–50 MPa and a temperature of 60–120 °C.

10. An application of a flexible encapsulation film based on two-dimensional materials as described in any one of claims 1 to 5, characterized in that, The encapsulation film has good flexibility and can be used to encapsulate optoelectronic devices in areas that require barrier protection by applying it, while also satisfying the bending and winding requirements of the devices.

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