Encapsulating film and method for producing same, flexible electronic device

Abstract

This application relates to the field of encapsulation materials technology, and more particularly to an encapsulation film and its preparation method, and flexible electronic devices. The encapsulation film of this application includes: an elastomer base film and a composite filler located within the elastomer base film. The composite filler includes an inorganic filler and a polymer coating layer covering the surface of the inorganic filler; wherein the inorganic filler has a one-dimensional and / or two-dimensional morphology, and at least a portion of the inorganic filler is arranged perpendicularly to the plane of the elastomer base film. Based on the combined effect of the elastomer base film and the composite filler, this application enables the encapsulation film to possess both tensile strength and high thermal conductivity, making it well-suited for use in the field of flexible electronic packaging.

Description

Technical Field

[0001] This application belongs to the field of packaging materials technology, and in particular relates to a packaging film and its preparation method, and flexible electronic devices. Background Technology

[0002] With the rapid development of flexible electronics technology, flexible electronic products are showing a trend towards multi-functional integration and miniaturization. Along with the increase in functionality, power consumption is also constantly increasing, placing higher demands on flexible electronic packaging. To ensure system reliability and performance, good thermal management becomes particularly important (such as heat dissipation for power devices or temperature sensing). Currently, flexible electronic packaging typically uses stretchable elastomer materials, which can deform synchronously with the electronic components, thereby effectively protecting the devices and ensuring their flexible functions. However, the elastomer materials used for flexible electronic device packaging are mostly silicon-based or carbon-based rubbers, which often have extremely low thermal conductivity, thus affecting device lifespan. Improving the thermal conductivity of the packaging film while ensuring it possesses good stretchability and can adapt to various deformations of flexible electronic devices is a key technical challenge.

[0003] Improving the thermal conductivity of elastomers typically requires enhancing the out-of-plane thermal conductivity of the encapsulation film to facilitate better Joule heat transfer from the device's internal components to the external environment. However, the commonly used strategy of blending inorganic fillers with the elastomer matrix often results in the thermally conductive inorganic fillers failing to form continuous thermal pathways within the matrix, thus limiting the improvement of out-of-plane thermal conductivity. Furthermore, while increasing the filler content can partially improve thermal conductivity, it also leads to a significant increase in the material's Young's modulus, thereby affecting its flexibility and tensile properties. Currently, how to improve the thermal conductivity of elastomers without significantly reducing their tensile strength remains a key technical challenge for the industry. Summary of the Invention

[0004] The purpose of this application is to provide an encapsulation film and its preparation method, as well as a flexible electronic device, aiming to solve the technical problem of how to make the encapsulation film have both good stretchability and thermal conductivity in order to better adapt to the encapsulation of flexible electronic devices.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides an encapsulation film comprising: an elastomer base film and a composite filler located in the elastomer base film, the composite filler comprising an inorganic filler and a polymer coating layer covering the surface of the inorganic filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology, and at least a portion of the inorganic filler is arranged perpendicularly along the plane of the elastomer base film.

[0006] In some embodiments, at least a portion of the inorganic filler penetrates the elastomeric base membrane perpendicularly along the plane of the elastomeric base membrane.

[0007] In some embodiments, the morphology of the inorganic filler includes at least one of microsheets, nanowires, and nanofibers; And / or, the inorganic filler material includes at least one of alumina, boron nitride, and silicon carbide; And / or, the material of the polymer coating layer includes at least one of cross-linked polystyrene, cross-linked polyethylene, and cross-linked polypropylene; And / or, the material of the elastomeric base film includes styrene-based block copolymers.

[0008] In some embodiments, the morphology of the inorganic filler includes micron-sized sheets, and the dimensions of the micron-sized sheets include: a thickness of 0.1 μm to 1 μm and a sheet diameter of 5 μm to 20 μm; or the morphology of the inorganic filler includes nanowires, and the dimensions of the nanowires include: a diameter of 50 nm to 300 nm and a length of 10 μm to 50 μm. And / or, the thickness of the polymer coating layer is 2nm~10nm; And / or, the thickness of the elastomer base film is 10 μm to 50 μm; And / or, based on the total volume of the encapsulating film, the volume percentage of the inorganic filler is 1% to 10%.

[0009] Secondly, this application provides a method for preparing an encapsulation film, comprising: A polymer coating layer is prepared on the surface of an inorganic filler to obtain a composite filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology. Prepare a precursor solution containing the composite filler and the elastomer substrate; The precursor solution is coated onto the surface of a liquid substrate to form an initial liquid layer. Then, a converging airflow is provided above the initial liquid layer to induce converging shear flow in the initial liquid layer. After the solvent in the initial liquid layer evaporates, an encapsulation film is obtained.

[0010] In some embodiments, providing a converging airflow above the initial liquid layer includes: placing a mask having an array of circular holes above the initial liquid layer, and performing a suction process on the mask in a direction away from the initial liquid layer, so that a converging airflow is formed between the mask and the initial liquid layer.

[0011] In some embodiments, the array of circular holes in the mask includes: a hole diameter of 0.1 mm to 0.6 mm and a hole spacing of 0.1 mm to 0.6 mm; And / or, the distance between the mask and the initial liquid layer ranges from 3mm to 10mm; And / or, the gas flow rate generated by the gas extraction process is 1m / s to 3m / s.

[0012] In some embodiments, the preparation of the polymer coating layer on the surface of the inorganic filler includes: mixing the inorganic filler with a polymeric monomer, a crosslinking agent and an initiator, and then performing a polymerization reaction to form the polymer coating layer on the surface of the inorganic filler; wherein the polymeric monomer includes at least one of styrene, ethylene and propylene; And / or, the preparation of the precursor solution containing the composite filler and the elastomer substrate includes: dissolving the elastomer substrate in a first organic solvent to obtain a first solution, dissolving the composite filler in a second organic solvent to obtain a second solution, and mixing the first solution and the second solution to obtain the precursor solution; wherein the concentration of the elastomer substrate in the first solution is 50 mg / mL to 200 mg / mL, the concentration of the inorganic filler in the second solution is 20 mg / mL to 55 mg / mL, and the ratio of the elastomer substrate to the inorganic filler in the precursor solution is calculated as a volume ratio of 99:1 to 90:10 in the final encapsulation film; or adding a third organic solvent with a higher saturated vapor pressure than the first organic solvent and the second organic solvent during the mixing of the first solution and the second solution.

[0013] In some embodiments, the liquid substrate includes at least one of glycerol, ethylene glycol, and fluorinated oil; And / or, the morphology of the inorganic filler includes at least one of microsheets, nanowires, and nanofibers; And / or, the inorganic filler material includes at least one of alumina, boron nitride, and silicon carbide; And / or, the elastomer substrate comprises a styrene-based block copolymer.

[0014] Thirdly, this application provides a flexible electronic device, which includes the encapsulation film provided in the first aspect of this application and / or the encapsulation film prepared by the preparation method provided in the second aspect of this application.

[0015] In the encapsulation film provided by the first aspect of this application, the surface of the inorganic filler with thermal conductivity is modified by a polymer coating layer, thereby reducing the surface energy of the inorganic filler and improving its interfacial compatibility with the elastomeric base film. This composite filler can be uniformly dispersed in the elastomeric base film, and at least some of the inorganic filler can be vertically aligned along the plane of the elastomeric base film. The vertical alignment of one-dimensional / two-dimensional inorganic fillers allows the encapsulation film to dissipate heat more uniformly. Therefore, based on the combined effect of the elastomeric base film and the composite filler, this application enables the encapsulation film to possess both tensile strength and high thermal conductivity, making it well-suited for use in the field of flexible electronic packaging.

[0016] In the preparation method provided in the second aspect of this application, the composite filler with polymer coating layer modified on the surface of inorganic filler can be uniformly dispersed with the elastomer substrate in the precursor solution. After the precursor solution is coated on the surface of the liquid substrate to form an initial liquid layer, a converging airflow is provided above the initial liquid layer to generate converging shear flow in the initial liquid layer. In this way, the two-dimensional / one-dimensional inorganic filler can be vertically aligned based on the liquid-liquid interface assisted converging shear flow, thereby preparing an encapsulation film with both tensile properties and high thermal conductivity.

[0017] The flexible electronic device provided in the third aspect of this application includes the encapsulation film provided in this application and / or the encapsulation film prepared by the preparation method provided in this application. Based on the fact that the encapsulation film has both stretchability and high thermal conductivity, the flexible electronic device of this application is not easy to break or be damaged when it is deformed, and it has good heat dissipation, is not easy to cause temperature runaway due to heat accumulation, and greatly extends the service life of the device. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of an operation method for preparing the encapsulation film of this application; Figure 2 These are SEM comparison images of the encapsulation film prepared in Example 1 of this application and the encapsulation film prepared by natural evaporation (S-NE) at the liquid-solid interface. Figure 3 These are XRD pole figures comparing the encapsulation film prepared in Example 1 of this application and the encapsulation film prepared by natural evaporation (S-NE) at the liquid-solid interface; Figure 4 This is a comparison of the azimuth curves of the encapsulation film prepared in Example 1 of this application and the encapsulation film prepared by natural evaporation (S-NE) at the liquid-solid interface; Figure 5 These are SEM comparison images of the encapsulation film prepared in Example 1 of this application and the encapsulation film formed by inorganic filler without polymer coating layer modification; Figure 6 This is a comparison chart of the thermal conductivity of the encapsulation film prepared in Example 1 of this application, the elastomer base film, the encapsulation film prepared by natural evaporation (S-NE) at the liquid-solid interface, and the pure SIBS film. Figure 7This is a comparison chart of the thermal conductivity of the encapsulation films prepared in Examples 2 and 3 of this application and the encapsulation films prepared by natural evaporation (S-NE) at the liquid-solid interface. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0022] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0023] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0024] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0025] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0026] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0027] Flexible electronic devices refer to electronic devices that integrate organic or inorganic electronic materials onto a flexible substrate (such as plastic, metal foil, or ultra-thin silicone), enabling them to maintain normal function under mechanical deformation conditions such as bending, folding, stretching, and even torsion. To withstand various deformations, the encapsulation film must possess good stretchability to prevent easy breakage or damage, providing effective protection. High thermal conductivity effectively dissipates the heat generated during device operation to the external environment, preventing temperature runaway due to heat accumulation and significantly extending the device's lifespan. Therefore, improving the thermal conductivity of the encapsulation film while ensuring good stretchability and adaptability to various deformations of flexible electronic devices is a key technical challenge.

[0028] Thermal management in flexible electronics (such as heat dissipation for power devices or temperature sensing) typically requires the thin film used for encapsulation to achieve rapid, directional heat dissipation or transfer. This necessitates the development of high thermal conductivity composite encapsulation films with vertically aligned filler structures. Current common processes for fabricating vertically aligned filler structures often struggle to achieve ultra-thin thicknesses and are complex and demanding. Furthermore, the interfacial thermal resistance between fillers is also a major challenge limiting the improvement of thermal conductivity. Although numerous studies have utilized interface engineering to improve this interfacial thermal resistance, the results remain limited. Therefore, there is an urgent need to develop a simple process that can directly form vertical thermal conduction pathways in a liquid-phase environment, particularly one that enables vertical penetration of a single functional unit. This is of great significance for the thermal management encapsulation of flexible electronic devices.

[0029] Based on the above description, this application develops an encapsulation film in which two-dimensional / one-dimensional inorganic fillers are vertically arranged along the plane of an elastomer base film after being coated with a polymer coating layer. It also proposes a method for preparing the encapsulation film with vertically arranged two-dimensional / one-dimensional inorganic fillers based on liquid-liquid interface-assisted convergent shear flow induction, addressing the challenge of inorganic fillers forming vertical structures in a liquid environment. This encapsulation film preparation scheme based on liquid-liquid interface-assisted convergent shear flow induction provides an effective solution to the contradiction between thermal conductivity and stretchability in the field of flexible electronic packaging. The technical solution is described in detail below.

[0030] In a first aspect, embodiments of this application provide an encapsulation film. Specifically, the encapsulation film of this application is a stretchable encapsulation film (L-CSF), comprising: an elastomer base film and a composite filler located within the elastomer base film. The composite filler includes an inorganic filler and a polymer coating layer covering the surface of the inorganic filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology, and at least a portion of the inorganic filler is arranged perpendicularly along the plane of the elastomer base film.

[0031] In this embodiment, the surface of the thermally conductive inorganic filler is modified with a polymer coating layer, thereby reducing the surface energy of the inorganic filler and improving its interfacial compatibility with the elastomer base film. This composite filler can be uniformly dispersed in the elastomer base film, and at least some of the inorganic filler can be vertically aligned along the plane of the elastomer base film. The vertical alignment of one-dimensional / two-dimensional inorganic fillers allows the encapsulation film to dissipate heat more uniformly. Therefore, based on the combined effect of the elastomer base film and the composite filler, this application enables the encapsulation film to possess both tensile strength and high thermal conductivity, making it well-suited for use in flexible electronic packaging.

[0032] In some embodiments, at least a portion of the inorganic fillers in the encapsulation film are arranged perpendicularly to the plane of the elastomeric base film. Optionally, all the inorganic fillers in the encapsulation film are arranged perpendicularly to the plane of the elastomeric base film. Further, at least a portion of the inorganic fillers penetrate the elastomeric base film perpendicularly to the plane of the elastomeric base film.

[0033] "Vertical penetration" of inorganic fillers means that the edges of the inorganic fillers should be exposed or flush with the surface of the encapsulation film. In practice, due to the varying sizes of inorganic fillers, not all filler diameters reach the thickness of the encapsulation film. Therefore, some inorganic fillers can penetrate and expose both sides of the encapsulation film, while others only expose one side. The vertical penetration of the inorganic filler along the plane of the elastomeric base film helps reduce the interfacial thermal resistance between the inorganic filler and the elastomeric base film, thereby further improving thermal conductivity.

[0034] In some embodiments, the inorganic filler can be two-dimensional (sheet-like) or one-dimensional (linear, fibrous) in shape. Such anisotropic fillers can achieve directional alignment, thereby constructing a unique three-dimensional structure. For example, the morphology of the inorganic filler includes at least one of microsheets, nanowires, and nanofibers. Two-dimensional or one-dimensional inorganic fillers with high thermal conductivity and large aspect ratio can serve as thermally conductive fillers and are well used to improve the thermal conductivity of encapsulation films.

[0035] In some embodiments, the inorganic filler material includes at least one of alumina, boron nitride, and silicon carbide; these inorganic materials have excellent thermal conductivity. For example, highly thermally conductive inorganic fillers are alumina (Al2O3) microsheets, silicon carbide (SiC) nanowires, boron nitride (BN) microsheets, etc., with Al2O3 microsheets being preferred.

[0036] In some embodiments, the morphology of the inorganic filler includes micron-sized sheets, and the dimensions of the micron-sized sheets include a thickness of 0.1 μm to 1 μm and a sheet diameter of 5 μm to 20 μm; or the morphology of the inorganic filler includes nanowires, and the dimensions of the nanowires include a diameter of 50 nm to 300 nm and a length of 10 μm to 50 μm. For example, Al₂O₃ micron-sized sheets have a thickness of 0.1 to 0.5 μm and a sheet diameter of 10 to 20 μm. BN micron-sized sheets have a thickness of 0.3 to 1 μm and a sheet diameter of 5 to 20 μm. SiC nanowires have a diameter of 50 to 300 nm and a length of 10 to 50 μm.

[0037] In some embodiments, the inorganic filler film has a polymer coating layer, forming a composite filler. The selected inorganic filler is modified by surface polymer coating to improve its interfacial compatibility with the elastomer base film, reduce the surface energy of the inorganic filler, provide steric hindrance, improve the dispersibility of the inorganic filler, and inhibit agglomeration.

[0038] The polymer coating material includes at least one of cross-linked polystyrene, cross-linked polyethylene, and cross-linked polypropylene. These oleophilic surface-modified polymer coatings can effectively reduce the surface energy of inorganic fillers, improve their interfacial compatibility with the elastomer base film, and promote their uniform dispersion and vertical orientation.

[0039] In some embodiments, the thickness of the polymer coating layer is 2 nm to 10 nm; exemplaryly, the thickness of the polymer coating layer can be any of the above values, such as 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, or within any range of both. A polymer coating layer within this thickness range can effectively modify the inorganic filler to achieve good interfacial compatibility with the elastomer base film.

[0040] In some embodiments, the material of the elastomeric base film includes styrene-based block copolymers. Styrene-based block copolymers (SBCs) composed of butadiene, isobutylene, and other compounds with styrene possess excellent biocompatibility, water and oxygen barrier properties, and are characterized by flexibility, stretchability, and strong structural processability, making them well-suited for applications in flexible and stretchable device encapsulation. Examples include styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butene-styrene (SEBS), styrene-isobutylene-styrene (SIBS), styrene-propylene-styrene (SEPS), and styrene-ethylene-propylene-styrene (SEPES); optionally, some embodiments may use SIBS with low water vapor permeability.

[0041] In some embodiments, the thickness of the elastomeric base film is 10 μm to 50 μm; exemplaryly, the elastomeric base film can be any of the above values ​​or within any range of both, such as 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 45 μm, 50 μm, etc. This thickness range allows the encapsulation film to have good tensile properties, making it well-suited for flexible electronic packaging.

[0042] In some embodiments, the volume percentage of inorganic filler, based on the total volume of the encapsulation film, is 1% to 10%. For example, the volume percentage of inorganic filler in the encapsulation film can be any of the above values, such as 1%, 2%, 3%, 4%, 5%, 6%, 8%, 9%, 10%, etc., or within any range of both. Specifically, the volume ratio of the elastomer substrate to the inorganic filler in the encapsulation film is 99:1 to 90:10; encapsulation films within this ratio range exhibit both excellent tensile strength and high thermal conductivity.

[0043] Secondly, embodiments of this application provide a method for preparing an encapsulation film. Specifically, the method for preparing the encapsulation film of this application includes the following steps: S01: A polymer coating layer is prepared on the surface of an inorganic filler to obtain a composite filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology; S02: Prepare a precursor solution containing composite fillers and elastomer substrates; S03: The precursor solution is coated on the surface of the liquid substrate to form an initial liquid layer. Then, a converging airflow is provided above the initial liquid layer to generate a converging shear flow in the initial liquid layer. After the solvent in the initial liquid layer evaporates, the encapsulation film is obtained.

[0044] In the preparation method of this application embodiment, the composite filler with polymer coating layer modified on the surface of inorganic filler can be uniformly dispersed with elastomer substrate in precursor solution. After the precursor solution is coated on the surface of liquid substrate to form initial liquid layer, a converging airflow is provided above the initial liquid layer to generate converging shear flow in the initial liquid layer. In this way, the two-dimensional / one-dimensional inorganic filler can be vertically aligned based on the liquid-liquid interface assisted converging shear flow, thereby preparing an encapsulation film with both tensile properties and high thermal conductivity.

[0045] Step S01 is the preparation step of the composite filler.

[0046] Based on similar interfacial compatibility principles, polymer coating of inorganic fillers and oleophilic surface modification can reduce the surface energy of the fillers, improve their interfacial compatibility with elastic substrates, and promote their uniform dispersion in solution and subsequent vertical orientation process.

[0047] In some embodiments, preparing a polymer coating layer on the surface of an inorganic filler includes: mixing the inorganic filler with a polymeric monomer, a crosslinking agent, and an initiator, followed by a polymerization reaction to form a polymer coating layer on the surface of the inorganic filler; wherein the polymeric monomer is a precursor of the polymer coating layer, including at least one of styrene, ethylene, and propylene. This allows the formation of a polymer coating layer on the surface of the inorganic filler, including at least one of crosslinked polystyrene, crosslinked polyethylene, and crosslinked polypropylene. The polymer coating layer modification treatment described in this application can improve the interfacial compatibility between the inorganic filler and the elastomer substrate, and enhance its dispersibility in solution.

[0048] Taking the surface crosslinking polystyrene coating modification of inorganic filler as an example. The specific steps include: (1) Pre-dispersion: Mix an appropriate amount of inorganic filler with styrene monomer, crosslinking agent and initiator in proportion, and then stir and sonicate to make the inorganic filler uniformly dispersed. In some embodiments, the crosslinking agent can be 1,3-diisopropenylbenzene, the initiator can be azobisisobutyronitrile, and the mass ratio of polymer monomer and crosslinking agent and initiator can be 100:(1~3):(0.05~0.5). (2) In-situ polymerization: Under nitrogen protection, the above mixture is polymerized at 70~80°C for 1~3 hours to form a crosslinked polystyrene coating layer on the surface of the inorganic filler. (3) Post-treatment: After the reaction, the unreacted material is removed by centrifugation and washing with non-polar solvent, and finally vacuum dried to obtain the coated modified composite filler. By adjusting the mass ratio of polymer monomer and crosslinking agent and initiator and the reaction temperature and time, the thickness of the polymer coating layer is finally about 2nm~10nm.

[0049] In some embodiments, the inorganic filler can be two-dimensional (sheet-like) or one-dimensional (linear, fibrous) in shape. Such anisotropic fillers can achieve directional alignment, thereby constructing a unique three-dimensional structure. For example, the morphology of the inorganic filler includes at least one of microsheets, nanowires, and nanofibers. Two-dimensional or one-dimensional inorganic fillers with high thermal conductivity and large aspect ratio can serve as thermally conductive fillers, effectively improving the thermal conductivity of encapsulation films. For example, highly thermally conductive inorganic fillers include alumina (Al2O3) microsheets, silicon carbide (SiC) nanowires, boron nitride (BN) microsheets, etc., with Al2O3 microsheets being preferred.

[0050] For example, the morphology of inorganic fillers includes micron-sized sheets, with dimensions including a thickness of 0.1 μm to 1 μm and a sheet diameter of 5 μm to 20 μm; or the morphology of inorganic fillers includes nanowires, with dimensions including a diameter of 50 nm to 300 nm and a length of 10 μm to 50 μm. For example, Al₂O₃ micron-sized sheets have a thickness of 0.1 to 0.5 μm and a sheet diameter of 10 to 20 μm. BN micron-sized sheets have a thickness of 0.3 to 1 μm and a sheet diameter of 5 to 20 μm. SiC nanowires have a diameter of 50 to 300 nm and a length of 10 to 50 μm.

[0051] The embodiments of this application can utilize the convergent shear flow effect assisted by the liquid-liquid interface to drive such anisotropic inorganic packings to achieve directional alignment, thereby constructing a unique three-dimensional structure.

[0052] Step S02 is the preparation step of the precursor solution.

[0053] In some embodiments, preparing a precursor solution containing a composite filler and an elastomer substrate includes: dissolving the elastomer substrate in a first organic solvent to obtain a first solution, dissolving the composite filler in a second organic solvent to obtain a second solution, and mixing the first and second solutions to obtain a precursor solution; wherein the concentration of the elastomer substrate in the first solution is 50-200 mg / mL, the concentration of the inorganic filler in the second solution is 20-55 mg / mL, and the ratio of the elastomer substrate to the inorganic filler in the precursor solution is based on a volume ratio of 99:1 to 90:10 in the final encapsulated film. This process allows the elastomer substrate and the inorganic filler to be uniformly dispersed in the precursor solution.

[0054] For example, the concentration of the elastomer substrate in the first solution can be any of the above values ​​or within any range of any two, such as 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, 100 mg / mL, 120 mg / mL, 140 mg / mL, 150 mg / mL, 160 mg / mL, 180 mg / mL, 190 mg / mL, 200 mg / mL, etc.; within the above concentration range, the elastomer substrate can be more uniformly dispersed in the first solution. For example, the concentration of the inorganic filler in the second solution can be any of the above values ​​or within any range of any two, such as 20 mg / mL, 25 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 55 mg / mL, etc.; within the above concentration range, the inorganic filler can be more uniformly dispersed in the second solution.

[0055] For example, the ratio of elastomeric substrate to inorganic filler in the precursor solution can be adjusted to a volume ratio of 99:1 to 90:10 in the final encapsulation film, thereby making the volume percentage of inorganic filler in the final encapsulation film 1% to 10%. Simultaneously, the thickness of the final encapsulation film can be increased to 10 μm to 50 μm by adjusting the concentration of the elastomeric substrate in the precursor solution.

[0056] In a specific embodiment, the elastomer substrate is fully dissolved using an organic solvent dissolution method according to a precise volume ratio. This solution is then mixed with a solution formed by dispersing a selected inorganic filler polymer in an organic solvent, ensuring uniform dispersion so that the two materials are fully mixed and form a homogeneous precursor solution. The first organic solvent can be a non-polar organic solvent such as toluene or n-hexane, and the second organic solvent can also be a non-polar organic solvent such as toluene or n-hexane. The first and second organic solvents can be the same or different.

[0057] For example, firstly, a non-polar organic solvent such as toluene or n-hexane is selected as the first organic solvent to completely dissolve the elastomer substrate raw material, obtaining a first solution. The elastomer substrate raw material is then dissolved using a magnetic stirrer to ensure complete dissolution of the particles. Next, the selected polymer-coated modified inorganic filler is added to the non-polar organic solvent such as toluene or n-hexane, i.e., the second organic solvent, and dispersed uniformly using a magnetic stirrer and ultrasonic equipment to form the second solvent. This preparation process can be carried out at room temperature (25~30℃). Then, at room temperature, the second solution is mixed with the first solution, and the mixture is further stirred or ultrasonicated (for at least 30 minutes) until homogeneous, ultimately obtaining a uniform precursor solution.

[0058] In some embodiments, a third organic solvent with a higher saturated vapor pressure than the first and second organic solvents can be added to the precursor solution. For example, the third organic solvent with a higher saturated vapor pressure than the first and second organic solvents can be added during the mixing of the first and second solutions. For example, the first solution, the second solution, and the third organic solvent are mixed to obtain the precursor solution. Because the saturated vapor pressure of this third organic solvent is higher than that of the first and second organic solvents, the evaporation rate of the solvent will differ during the solvent evaporation process of the precursor solution to prepare the thin film. This is beneficial for further controlling the hydrodynamic behavior in the precursor solution and inducing the vertical alignment of the inorganic filler. For example, the first and second organic solvents can be toluene, and the third organic solvent can be cyclopentane.

[0059] In some embodiments, the elastomer substrate comprises a styrene-based block copolymer. For example, it may be a styrene-based block copolymer such as styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butene-styrene (SEBS), styrene-isobutene-styrene (SIBS), styrene-propylene-styrene (SEPS), or styrene-ethylene-propylene-styrene (SEPES).

[0060] In some embodiments of this application, SBCs are used as the elastomer base film material, and high thermal conductivity, wide aspect ratio inorganic fillers are used as thermally conductive fillers. The encapsulation film with an inorganic filler vertical through-structure is prepared by using the convergent shear flow effect assisted by the liquid-liquid interface.

[0061] Step S03 is the precursor solution film formation step.

[0062] In some embodiments, applying a precursor solution to the surface of a liquid substrate to form an initial liquid layer and providing a converging airflow above the initial liquid layer includes: placing a mask with an array of circular holes above the initial liquid layer and performing a suction process on the mask in a direction away from the initial liquid layer, so that a converging airflow is formed between the mask and the initial liquid layer.

[0063] like Figure 1As shown, a precursor solution containing an elastomer substrate and polymer-coated modified inorganic fillers is stirred and ultrasonically dispersed until homogeneous. At room temperature, a certain amount of the precursor solution is directly dropped onto the surface of a liquid substrate, forming an initial liquid layer after spreading. Subsequently, a mask with an array of circular holes is suspended above the surface of the initial liquid layer. A fan is used to draw air upwards, creating a converging airflow below the mask, causing the precursor solution in the initial liquid layer to undergo converging shear flow. This process minimizes the influence of ambient airflow on the solvent flow within the precursor solution; for example, it can be performed in a windless indoor environment. After the solvent has completely evaporated, an encapsulation film is formed below the mask.

[0064] In the above process, the hydrodynamics during solvent evaporation can be controlled by adjusting parameters such as the concentration ratio of the precursor solution, solvent type, pumping rate, mask aperture, and aperture spacing. Furthermore, after the solvent has completely evaporated and dried, the encapsulation film is lifted from the liquid substrate surface, rinsed with deionized water and ethanol to remove the adhering substrate liquid, and then stored in a vacuum oven (for example, for 10-12 hours) to better remove residual solvent from the encapsulation film.

[0065] Based on the converging shear flow induced by airflow from organic solvents, inorganic fillers can form a vertically aligned structure within an elastomer matrix. During preparation, if the distance between the mask and the initial liquid layer is too short, excessive airflow can cause excessive disturbance to the precursor solution; if the distance is too long, the airflow's hydrodynamic influence on the solution will be too weak, making it difficult to form a vertically aligned structure. Therefore, in some embodiments, the distance between the mask and the initial liquid layer is in the range of 3mm to 10mm, which effectively achieves the vertical alignment of the inorganic fillers.

[0066] In some embodiments, the array of circular holes in the mask includes: a hole diameter of 0.1 mm to 0.6 mm and a hole spacing of 0.1 mm to 0.6 mm (i.e., the shortest distance between the edges of two adjacent circular holes); the circular hole size of the mask can well realize the vertical arrangement of inorganic fillers.

[0067] In some embodiments, the gas flow rate generated by the extraction process is 1 m / s to 3 m / s. This gas flow rate can effectively achieve the vertical alignment of the inorganic packing material.

[0068] In some embodiments, the liquid substrate includes at least one of glycerol, ethylene glycol, and fluorinated oil; for preparation systems based on liquid-liquid interfaces, a suitable liquid can be selected as the substrate. In specific embodiments of this application, the selected liquid can be a liquid with high viscosity and not miscible with the selected organic solvent in the precursor solution, such as glycerol, ethylene glycol, or fluorinated oil; for example, glycerol with low interfacial tension with benign solvents is selected.

[0069] In summary, the embodiments of this application utilize the convergent shear flow effect assisted by the liquid-liquid interface to achieve the vertical arrangement of inorganic fillers within the elastomer encapsulation film, and successfully enable the vertical through-type arrangement of individual functional units (i.e., individual high thermal conductivity inorganic fillers). This allows for the fabrication of stretchable high thermal conductivity encapsulation films with vertically penetrating high thermal conductivity inorganic fillers, effectively bridging the contradiction between thermal conductivity and stretchability in the field of flexible electronic packaging, and providing a widely applicable solution for the thermal management packaging of flexible and stretchable electronic products.

[0070] In some embodiments, the encapsulation film provided in the first aspect of this application is prepared by the preparation method provided in the second aspect of this application.

[0071] Thirdly, embodiments of this application provide a flexible electronic device. Specifically, the flexible electronic device of this application includes the encapsulation film provided in the first aspect of this application and / or the encapsulation film prepared by the preparation method provided in the second aspect of this application.

[0072] The flexible electronic device in this application embodiment is encapsulated using the unique encapsulation film described above. Based on the fact that the encapsulation film has both stretchability and high thermal conductivity, the flexible electronic device in this application embodiment is not easily broken or damaged when deformed, and it also has good heat dissipation, making it less prone to temperature runaway due to heat accumulation, thus greatly extending the service life of the device.

[0073] In some embodiments, flexible electronic devices include at least one of solar cells (such as perovskite solar cells), electronic skin, and soft robots; for example, they may be wearable or implantable electronic devices.

[0074] The following description is based on specific embodiments.

[0075] Example 1 A method for preparing an encapsulation film includes the following steps: S11: Preparation of composite fillers.

[0076] Pre-dispersion: Inorganic filler (Al2O3 micron flakes: thickness 0.1~0.5μm, flake diameter 10~20μm) is mixed with styrene monomer, crosslinking agent and initiator (wherein, the crosslinking agent is 1,3-diisopropenylbenzene, the initiator is azobisisobutyronitrile, and the mass ratio of styrene monomer, crosslinking agent and initiator is 100:2:0.1), and the mixture is stirred and ultrasonically treated to make the materials uniformly dispersed.

[0077] In-situ polymerization: Under nitrogen protection, the above pre-dispersed material is polymerized at 70°C for 3 hours to form a cross-linked polystyrene coating layer of about 3 nm on the surface of Al2O3 micron sheets.

[0078] Post-processing: After the reaction is completed, the unreacted material is removed by centrifugation and washing with a non-polar solvent, and finally vacuum drying is performed to obtain the composite filler.

[0079] S12: Preparation of precursor solution.

[0080] First, prepare 10 mL of a 200 mg / mL SIBS solution: Accurately weigh 2 g of SIBS particles into a beaker, add 10 mL of toluene, place it on a magnetic stirrer, and stir at 300 rpm for 5 hours until the SIBS dissolves, obtaining a 200 mg / mL SIBS solution, i.e., the first solution. Next, weigh the above composite filler (based on 11 mg of Al2O3 micron flakes) and add it to 200 μL of toluene. After homogenizing using a vortex mixer, place it in an ultrasonic cleaner for ultrasonic treatment for 20 minutes to ensure the composite filler is evenly dispersed in the toluene, obtaining the second solution.

[0081] Add 50 μL of cyclopentane and 250 μL of SIBS solution with a concentration of 200 mg / mL (i.e., the first solution) sequentially to the above 200 μL second solution, and then vortex the mixture again to obtain the precursor solution.

[0082] S13: Formation of encapsulation film.

[0083] Take a 6cm diameter glass culture dish and pour in an appropriate amount of glycerol, ensuring the glycerol level is flush with the edge of the dish. Use a pipette to add 100μL of the precursor solution to the glycerol surface. Then, suspend a mask with an array of circular holes (0.2mm diameter, 0.2mm spacing) 5mm above the liquid surface and use a fan to evacuate upwards at a flow rate of 2.5m / s. After 3 minutes, the solvent completely evaporates, forming an encapsulation film (Al₂O₃ / SIBS composite film) beneath the mask. Remove the encapsulation film, rinse with deionized water and ethanol, and store in a vacuum oven at 60°C for 12 hours to remove residual organic solvent.

[0084] Example 2 A method for preparing an encapsulation film includes the following steps: S21: Preparation of composite fillers.

[0085] Pre-dispersion: Inorganic filler (BN micron flakes, size: thickness 0.3~1μm, flake diameter 5~20μm) is mixed with styrene monomer, crosslinking agent and initiator (wherein, the crosslinking agent is 1,3-diisopropenylbenzene, the initiator is azobisisobutyronitrile, and the mass ratio of styrene monomer, crosslinking agent and initiator is 100:2:0.1), and the mixture is stirred and ultrasonically treated to make the materials uniformly dispersed.

[0086] In-situ polymerization: Under nitrogen protection, the above pre-dispersed material is polymerized at 70°C for 3 hours to form a cross-linked polystyrene coating layer of about 3 nm on the surface of BN microsheets.

[0087] Post-processing: After the reaction is completed, the unreacted material is removed by centrifugation and washing with a non-polar solvent, and finally vacuum drying is performed to obtain the composite filler.

[0088] S22: Preparation of precursor solution.

[0089] First, prepare 10 mL of a 200 mg / mL SIBS solution: Accurately weigh 2 g of SIBS particles into a beaker, add 10 mL of toluene, place it on a magnetic stirrer, and stir at 300 rpm for 5 hours until the SIBS dissolves, obtaining a 200 mg / mL SIBS solution, i.e., the first solution. Next, weigh the above composite filler (based on 6.5 mg of BN micron flakes) and add it to 200 μL of toluene. After homogenizing using a vortex mixer, place it in an ultrasonic cleaner for ultrasonic treatment for 20 minutes to disperse the composite filler evenly in the toluene, obtaining the second solution.

[0090] Add 50 μL of cyclopentane and 250 μL of SIBS solution with a concentration of 200 mg / mL (i.e., the first solution) sequentially to the above 200 μL second solution, and then vortex the mixture again to obtain the precursor solution.

[0091] S23: Formation of encapsulation film.

[0092] Take a 6cm diameter glass culture dish and pour in an appropriate amount of glycerol, ensuring the glycerol level is flush with the edge of the dish. Use a pipette to add 100μL of the precursor solution to the glycerol surface. Then, suspend a mask with an array of circular holes (0.2mm diameter, 0.2mm spacing) 5mm above the liquid surface and use a blower to evacuate upwards at a flow rate of 2.5m / s. After 3 minutes, the solvent has completely evaporated, forming an encapsulation film (BN / SIBS composite film) beneath the mask. Remove the encapsulation film, rinse with deionized water and ethanol, and store in a vacuum oven at 60°C for 12 hours to remove residual organic solvent.

[0093] Example 3 A method for preparing an encapsulation film includes the following steps: S31: Preparation of composite fillers.

[0094] Pre-dispersion: Inorganic filler (SiC nanowire size: diameter 50~300 nm, length 10~50 μm) is mixed with styrene monomer, crosslinking agent and initiator (wherein, the crosslinking agent is 1,3-diisopropenylbenzene, the initiator is azobisisobutyronitrile, and the mass ratio of styrene monomer, crosslinking agent and initiator is 100:2:0.1). The mixture is stirred and ultrasonically treated to make the materials uniformly dispersed.

[0095] In-situ polymerization: Under nitrogen protection, the above pre-dispersed material is polymerized at 70°C for 3 hours to form a cross-linked polystyrene coating layer of about 3 nm on the surface of BN microsheets.

[0096] Post-processing: After the reaction is completed, the unreacted material is removed by centrifugation and washing with a non-polar solvent, and finally vacuum drying is performed to obtain the composite filler.

[0097] S32: Preparation of precursor solution.

[0098] First, prepare 10 mL of a 200 mg / mL SIBS solution: Accurately weigh 2 g of SIBS particles into a beaker, add 10 mL of toluene, place it on a magnetic stirrer, and stir at 300 rpm for 5 hours until the SIBS dissolves, obtaining a 200 mg / mL SIBS solution, i.e., the first solution. Next, weigh the above composite filler (based on 9 mg of SiC nanowires) and add it to 200 μL of toluene. After homogenizing using a vortex mixer, place it in an ultrasonic cleaner for ultrasonic treatment for 20 minutes to disperse the composite filler evenly in the toluene, obtaining the second solution.

[0099] Add 50 μL of cyclopentane and 250 μL of SIBS solution with a concentration of 200 mg / mL (i.e., the first solution) sequentially to the above 200 μL second solution, and then vortex the mixture again to obtain the precursor solution.

[0100] S33: Encapsulation film formation.

[0101] Take a 6cm diameter glass culture dish and pour in an appropriate amount of glycerol, ensuring the glycerol level is flush with the edge of the dish. Use a pipette to add 100μL of the precursor solution to the glycerol surface. Then, suspend a mask with an array of circular holes (0.2mm diameter, 0.2mm spacing) 5mm above the liquid surface and use a fan to evacuate upwards at a flow rate of 2.5m / s. After 3 minutes, the solvent completely evaporates, forming an encapsulation film (SiC / SIBS composite film) beneath the mask. Remove the encapsulation film, rinse with deionized water and ethanol, and store in a vacuum oven at 60°C for 12 hours to remove residual organic solvent.

[0102] Performance testing: (1) Material characterization analysis The structure of the encapsulated thin film sample prepared in Example 1 was characterized: The microstructure of the cross-section of the encapsulation film prepared in Example 1 based on liquid-liquid interface-assisted converging shear flow (L-CSF) induction was observed using scanning electron microscopy (SEM), such as... Figure 2 As shown: The results show that the encapsulation film prepared in Example 1 (represented by L-CSF-Al2O3 in the figure) has Al2O3 microsheets forming a vertically penetrating structure in the vertical direction of the encapsulation film, while the encapsulation film prepared by liquid-solid interface natural evaporation (S-NE) (represented by S-NE-Al2O3 in the figure, the difference between this encapsulation film preparation method and Example 1 is that step S13 is replaced by the precursor solution being coated on the solid surface and then the solvent naturally evaporating to form a film, the rest is the same as Example 1) has Al2O3 microsheets arranged in a parallel stacked alignment.

[0103] Figure 3 This is the XRD pole figure (PF) of the encapsulation film of Example 1. In the figure, L-CSF represents the encapsulation film of Example 1, and S-NE represents the encapsulation film prepared by natural evaporation at the corresponding liquid-solid interface. The test results reveal the macroscopic orientation distribution of the crystal plane (006) representing the orientation of Al2O3 micron-plates in the sample, indicating the vertical orientation structure in L-CSF, while S-NE has a stronger parallel orientation structure. Figure 4 As shown, using PF to plot the azimuth curves, it can be found that L-CSF has the strongest orientation at 60°. Based on this, the initial Herman orientation factor calculated is H = 0.40 (the closer this factor is to 1, the higher the degree of orientation of the crystal plane perpendicular to the sample surface). The intensity of S-NE is mainly distributed below 10°, and the Herman orientation factor (H) calculated from this azimuth intensity distribution curve is -0.38; the closer this factor is to -0.5, the higher the degree of orientation of the crystal plane parallel to the sample surface. This further proves that L-CSF can induce a strong perpendicular orientation in Al2O3 microsheets. It should be noted that due to the geometric limitations of conventional laboratory X-ray sources, under large χ angles (i.e., sample height tilt), the X-ray incident angle becomes smaller, leading to a sharp decrease in the effective detection depth. Therefore, the signal attenuation observed in the region χ>65° is partly attributed to the limitations of this experimental system. The actual diffraction intensity in the region χ>65° may be underestimated; therefore, the true Herman orientation factor of the sample should be higher than the calculated initial value of 0.40.

[0104] In addition, the surface microstructure of the encapsulation film prepared in Example 1 based on liquid-liquid interface assisted converging shear flow (L-CSF) induction was observed using scanning electron microscopy (SEM), such as... Figure 5As shown: The left image in the figure shows the surface SEM morphology of the encapsulation film of Example 1, where one edge of a large number of Al2O3 microsheets is exposed or flush with the surface of the encapsulation film; The right image in the figure shows the morphology of the encapsulation film prepared without the modified inorganic filler (the difference between the preparation method of this encapsulation film and Example 1 is that step S11 is omitted, and the unmodified Al2O3 microsheets are directly prepared into a precursor solution, while the rest is the same as Example 1). It can be seen that the Al2O3 microsheet filler exhibits significant agglomeration. At the same time, the interfacial compatibility between the filler and the solvent and polymer matrix is ​​poor, resulting in a large amount of filler being enriched at the liquid-liquid interface, making it difficult to form a vertically penetrating structure inside the encapsulation film.

[0105] (2) Characterization and analysis of thermal conductivity of encapsulated thin film samples Figure 6 The out-of-plane thermal conductivity of the encapsulation film prepared in Example 1 based on liquid-liquid interface assisted converging shear flow (L-CSF) induction, the encapsulation film prepared by liquid-solid interface spontaneous evaporation (S-NE), and the pure SIBS film are demonstrated. The thermal conductivity of the encapsulation film in Example 1 can reach 2.2 W·m. -1 ·K -1 This represents an order of magnitude improvement over pure SIBS films, while the thermal conductivity of the encapsulation film prepared by S-NE is only 0.38 W·m. -1 ·K -1 .

[0106] Figure 7 The thermal conductivity of the encapsulation films prepared by liquid-liquid interface assisted converging shear flow (L-CSF) and liquid-solid interface spontaneous evaporation (S-NE) in Examples 2 and 3, respectively, using BN and SiC as inorganic fillers, is characterized. The vertically arranged high thermal conductivity inorganic fillers prepared by the L-CSF method in this application significantly improve the out-of-plane thermal conductivity of the encapsulation film.

[0107] The thermal conductivity test methods and conditions are as follows: First, the thermal diffusivity was tested using a laser flare method (Netzsch LFA467 equipment). The laser voltage was set to 150 V and the pulse width to 20 μs. Before testing, graphite was sprayed onto the sample surface to increase the sample's absorption rate of the laser and enhance the signal strength of the infrared detector, thus obtaining a more accurate thermal diffusivity measurement result. Finally, the obtained thermal diffusivity was used to calculate the thermal conductivity.

[0108] Thermal conductivity is calculated using the following formula:

[0109] In the formula Thermal conductivity (W·m)-1 ·K -1 ); Density (kg·m) - ³); Specific heat capacity at constant pressure (J·kg) -1 K -1 ); — Thermal diffusivity (m² / s); In this embodiment, the density is calculated by the water displacement method, and the specific heat capacity at constant pressure is calculated by differential scanning calorimetry (DSC) and sapphire method.

[0110] DSC testing was performed using a Netzsch DSC214, with the temperature program set to rise from 0°C to 100°C at a heating rate of 5°C / min. The specific heat capacity of the sample was calculated using the sapphire method, with the specific formula as follows:

[0111] In the formula Specific heat capacity of sample (J·kg) -1 K -1 ); Specific heat capacity of sapphire (J·kg) -1 K -1 ); Specific heat flux of sample (mW·mg) -1 ); Specific heat flux of sapphire (mW·mg) -1 ).

[0112] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An encapsulation film, characterized in that, include: An elastomer base film and a composite filler located in the elastomer base film, the composite filler comprising an inorganic filler and a polymer coating layer covering the surface of the inorganic filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology, and at least a portion of the inorganic filler is arranged perpendicularly to the plane of the elastomer base film.

2. The encapsulation film as described in claim 1, characterized in that, At least a portion of the inorganic filler penetrates the elastomeric base membrane perpendicularly along the plane of the elastomeric base membrane.

3. The encapsulation film as described in claim 1, characterized in that, The morphology of the inorganic filler includes at least one of micron-sheets, nanowires, and nanofibers; And / or, the inorganic filler material includes at least one of alumina, boron nitride, and silicon carbide; And / or, the material of the polymer coating layer includes at least one of cross-linked polystyrene, cross-linked polyethylene, and cross-linked polypropylene; And / or, the material of the elastomeric base film includes styrene-based block copolymers.

4. The encapsulation film according to any one of claims 1-3, characterized in that, The inorganic filler has the following morphology: micron-sized sheets with a thickness of 0.1 μm to 1 μm and a sheet diameter of 5 μm to 20 μm; or the inorganic filler has the following morphology: nanowires with a diameter of 50 nm to 300 nm and a length of 10 μm to 50 μm. And / or, the thickness of the polymer coating layer is 2nm~10nm; And / or, the thickness of the elastomer base film is 10 μm to 50 μm; And / or, based on the total volume of the encapsulating film, the volume percentage of the inorganic filler is 1% to 10%.

5. A method for preparing an encapsulation film, characterized in that, include: A polymer coating layer is prepared on the surface of an inorganic filler to obtain a composite filler; wherein the inorganic filler has a one-dimensional morphology and / or a two-dimensional morphology. Prepare a precursor solution containing the composite filler and the elastomer substrate; The precursor solution is coated onto the surface of a liquid substrate to form an initial liquid layer. Then, a converging airflow is provided above the initial liquid layer to induce converging shear flow in the initial liquid layer. After the solvent in the initial liquid layer evaporates, an encapsulation film is obtained.

6. The preparation method according to claim 5, characterized in that, Providing a converging airflow above the initial liquid layer includes: placing a mask with an array of circular holes above the initial liquid layer, and performing a suction process on the mask in a direction away from the initial liquid layer, so that a converging airflow is formed between the mask and the initial liquid layer.

7. The preparation method according to claim 6, characterized in that, The array of circular holes in the mask has the following dimensions: hole diameter 0.1mm~0.6mm, hole spacing 0.1mm~0.6mm; And / or, the distance between the mask and the initial liquid layer ranges from 3mm to 10mm; And / or, the gas flow rate generated by the gas extraction process is 1m / s to 3m / s.

8. The preparation method according to claim 5, characterized in that, The preparation of the polymer coating layer on the surface of the inorganic filler includes: mixing the inorganic filler with a polymeric monomer, a crosslinking agent and an initiator, and then carrying out a polymerization reaction to form the polymer coating layer on the surface of the inorganic filler; wherein the polymeric monomer includes at least one of styrene, ethylene and propylene; And / or, the preparation of the precursor solution containing the composite filler and the elastomer substrate includes: dissolving the elastomer substrate in a first organic solvent to obtain a first solution, dissolving the composite filler in a second organic solvent to obtain a second solution, and mixing the first solution and the second solution to obtain the precursor solution; wherein the concentration of the elastomer substrate in the first solution is 50 mg / mL to 200 mg / mL, the concentration of the inorganic filler in the second solution is 20 mg / mL to 55 mg / mL, and the ratio of the elastomer substrate to the inorganic filler in the precursor solution is calculated as a volume ratio of 99:1 to 90:10 in the final encapsulation film; or adding a third organic solvent with a higher saturated vapor pressure than the first organic solvent and the second organic solvent during the mixing of the first solution and the second solution.

9. The preparation method according to any one of claims 5-8, characterized in that, The liquid substrate includes at least one of glycerol, ethylene glycol, and fluorinated oil; And / or, the morphology of the inorganic filler includes at least one of microsheets, nanowires, and nanofibers; And / or, the inorganic filler material includes at least one of alumina, boron nitride, and silicon carbide; And / or, the elastomer substrate comprises a styrene-based block copolymer.

10. A flexible electronic device, characterized in that, The flexible electronic device includes the encapsulation film as described in any one of claims 1-4 and / or the encapsulation film prepared by the preparation method as described in any one of claims 5-9.

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