Multilayer composite dielectric thin film capacitor and preparation method thereof

Abstract

The invention relates to the technical field of semiconductors, and discloses a multilayer composite dielectric thin film capacitor and a preparation method thereof, and the preparation method comprises the steps: forming an inorganic thin film on the surface of one side of an organic thin film through a vapor deposition technology, and forming an organic-inorganic double-layer thin film; a plurality of organic-inorganic double-layer films are subjected to a pressing process, an organic film-inorganic film alternating structure with organic films and inorganic films on the outermost layers of the two sides is formed, and the inorganic film on the outermost layer is a first electrode contact layer; forming an inorganic thin film on the outer side of the organic thin film on the outermost layer of the organic thin film-inorganic thin film alternating structure to serve as a second electrode contact layer, and forming a multi-layer composite capacitor thin film with the inorganic thin films on the outermost layers on the two sides; and electrodes are respectively formed on the outer side of the first electrode contact layer and the outer side of the second electrode contact layer. The current conduction loss at the electrode contact interface can be reduced, and the breakdown strength and the charging and discharging efficiency of the capacitor are improved, so that the energy storage performance of the capacitor is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a multilayer composite dielectric film capacitor and a preparation method thereof. Background Art

[0002] There are various temperature-dependent conduction mechanisms in polymer dielectrics (for example, injected charge at the electrode / dielectric interface). When the ambient temperature gradually increases, these conduction mechanisms will cause the leakage current and conduction loss in the polymer dielectric to increase sharply, resulting in higher energy loss of the polymer film at high temperatures, thereby reducing the storage performance of the capacitor at high temperatures. In the related art, a multilayer polymer film with a "sandwich structure" is formed by thin film coating technology. However, in this solution, due to the low injection barrier at the contact interface between the organic polymer film and the electrode, the current leaks from the electrode to the inside of the electrical polymer film, which in turn leads to increased current conduction loss, and the capacitor has higher energy loss at high temperatures, which reduces the energy storage performance of the capacitor.

[0003] At present, thin film coating technology is mainly divided into two categories: chemical vapor deposition (CVD) and physical vapor deposition (PVD). Most CVD processes are carried out at high temperatures (above 300°C), while the melting points of most high energy storage density polymers are much lower than this temperature. For example, the melting point of P(VDF-HFP) is only ~160°C. Therefore, it is not feasible to perform CVD directly on high energy storage density polymer films. Most PVD processes usually require vacuum, cannot complete a continuous deposition process, and cannot directly form a multilayer thin film structure.

[0004] Therefore, a solution is needed to form a multilayer film structure without damaging the organic polymer film, thereby reducing the current conduction loss at the electrode contact interface while ensuring the high energy storage density of the organic polymer film, so that the capacitor has excellent energy storage characteristics at high temperatures. Summary of the Invention

[0005] In view of this, the present invention provides a multilayer composite dielectric film capacitor and a preparation method thereof to solve the problem in the related art that the injection barrier at the contact interface between the organic polymer film and the electrode is low, resulting in current leakage from the electrode to the interior of the electropolymer film, which in turn leads to increased current conduction loss, high energy loss of the capacitor at high temperature, and low energy storage performance of the capacitor.

[0006] In a first aspect, the present invention provides a method for preparing a multilayer composite dielectric film capacitor, the method comprising:

[0007] providing organic thin films;

[0008] forming an inorganic thin film on one surface of the organic thin film by a vapor deposition process to form an organic-inorganic double-layer thin film;

[0009] laminating a plurality of organic-inorganic bilayer films, wherein the organic film in each organic-inorganic bilayer film contacts the inorganic film in an adjacent organic-inorganic bilayer film, to form an alternating organic-inorganic film structure in which the outermost layers on both sides are organic films and inorganic films, respectively, and the outermost inorganic film serves as a first electrode contact layer;

[0010] An inorganic film is formed as a second electrode contact layer on the outer side of the outermost organic film of the organic film-inorganic film alternating structure by a vapor deposition process, thereby forming a multilayer composite capacitor film in which the outermost layers on both sides are inorganic films;

[0011] Electrodes are formed on the outer sides of the first electrode contact layer and the second electrode contact layer, respectively.

[0012] The present invention provides a method for preparing a multilayer composite dielectric film capacitor. First, an inorganic film is formed on one surface of an organic film by a vapor deposition process, and several organic-inorganic double-layer films are pressed together to form an organic film-inorganic film alternating structure. Finally, an inorganic film is formed on the outer side of the outermost organic film as a second electrode contact layer. The inorganic film can be formed at a low temperature by the vapor deposition process, thereby avoiding damage to the organic film and ensuring the high energy storage density of the organic polymer film. At the same time, the multilayer alternating structure is formed by a lamination process, which can simplify the process flow and reduce costs. Second, by forming a multilayer composite capacitor film as the dielectric of the capacitor, the interlayer interface between the organic film and the inorganic film can be used to capture carriers, thereby reducing the carrier mobility and further suppressing its high-temperature loss, thereby significantly suppressing low-field dielectric loss and high-field leakage loss, and improving the charge and discharge efficiency. At the same time, the interlayer interface can also slow down the damage of the carriers to the organic polymer molecular chain and enhance the breakdown field strength. Third, using an inorganic thin film as the first and second electrode contact layers can increase the charge injection barrier at the interface between the electrode and the dielectric, suppressing the amount of injected charge, reducing current conduction losses at the electrode contact interface, and improving charge and discharge efficiency. Simultaneously, a shielding layer is formed between the electrode and the interfaces between the multiple layers, which can also suppress charge injection and ion suppression. The method for preparing a multilayer composite dielectric thin film capacitor provided by the present invention can form a multilayer film structure without damaging the organic polymer film. This reduces current conduction losses at the electrode contact interface while maintaining the high energy storage density of the organic polymer film, improving the breakdown strength and charge and discharge efficiency of the capacitor, and thus improving the energy storage performance of the capacitor, resulting in a capacitor with a high energy storage density, low current conduction losses, and excellent energy storage characteristics at high temperatures.

[0013] In an optional embodiment, the organic film has a dielectric constant greater than 2 and a breakdown strength greater than 200 MV / m;

[0014] The band gap of the inorganic film is greater than 5eV and the breakdown strength is greater than 800MV / m;

[0015] The injection barrier at the interface between the inorganic thin film material and the electrode material is greater than the injection barrier at the interface between the organic thin film material and the electrode material.

[0016] The present invention provides a method for preparing a multilayer composite dielectric film capacitor. The injection barrier at the interface between the inorganic film material and the electrode material is greater than the injection barrier at the interface between the organic film material and the electrode material. By selecting a wide-bandgap, high-breakdown-strength inorganic film material to coat the organic film surface, and using the inorganic film as the first and second electrode contact layers, the charge injection barrier at the interface between the electrode and the inorganic film can be increased, the amount of injected charge can be suppressed, the current conduction loss at the electrode contact interface can be reduced, the charge-discharge efficiency can be improved, and the energy storage performance of the capacitor can be improved. At the same time, the interlayer interface between the organic film and the inorganic film can be used to reduce the mobility of carriers, significantly suppress low-field dielectric loss and high-field leakage loss, and further improve the breakdown strength and charge-discharge efficiency.

[0017] In an optional embodiment, the material of the organic film is PVDF and its copolymer;

[0018] The material of the inorganic thin film is aluminum oxide, silicon oxide or hafnium oxide;

[0019] The total number of layers of the multilayer composite capacitor film is 3 to 19 layers.

[0020] The present invention provides a method for preparing a multilayer composite dielectric film capacitor. On the one hand, the PVDF copolymer has not only a high polarization strength but also a high dielectric strength, thereby having a high energy storage density, which can enable the capacitor to have a high energy storage density. Inorganic films such as aluminum oxide, silicon oxide, or hafnium oxide have a low band gap and breakdown strength. The contact interface between the inorganic film and the electrode has a high charge injection barrier, which can reduce leakage current and conduction loss at the electrode contact interface and reduce energy loss at high temperatures, thereby enabling the capacitor to have excellent energy storage characteristics at high temperatures. On the other hand, the interlayer interface between the organic film and the inorganic film can significantly suppress low-field dielectric loss and high-field leakage conduction loss, thereby improving breakdown strength and charge-discharge efficiency. The total number of layers of the multilayer composite capacitor film is 3 to 19, and the number of interlayer interfaces between the organic film and the inorganic film is 2 to 17. This can improve the discharge energy density and charge-discharge efficiency of the multilayer composite capacitor film, while ensuring the surface uniformity of the inorganic film, thereby improving the energy storage performance and reliability of the capacitor.

[0021] In an optional embodiment, the material of the organic thin film is P(VDF-HFP) or P(VDF-TrFE-CFE);

[0022] The material of the inorganic film is silicon dioxide;

[0023] The total number of layers of the multilayer composite capacitor film is 5 to 15 layers.

[0024] The present invention provides a method for preparing a multilayer composite dielectric film capacitor, wherein the material of the organic film is P(VDF-HFP) or P(VDF-TrFE-CFE), and the material of the inorganic film is silicon dioxide. SiO2 has a wide bandgap greater than 9eV and a high breakdown strength greater than 800MV / m, and can be used as an inorganic insulating layer. At the same time, the injection barrier at the contact interface when SiO2 contacts the electrode is greater than the injection barrier at the contact interface when P(VDF-HFP) or P(VDF-TrFE-CFE) contacts the electrode material. Therefore, the SiO2 inorganic film serves as the first electrode contact layer and the second electrode contact layer in contact with the electrode, which can increase the charge injection barrier at the contact interface between the electrode and the inorganic film, suppress the amount of injected charge, reduce the current conduction loss at the electrode contact interface, improve the charging and discharging efficiency, and improve the energy storage performance of the capacitor. In addition, the total number of layers of the multilayer composite capacitor film is 5 to 15 layers, and the number of interlayer interfaces between the organic film and the inorganic film is 4 to 14. The number of interlayer interfaces can reduce the mobility of carriers, significantly suppress low-field dielectric loss and high-field leakage loss, further improve the breakdown strength and charge and discharge efficiency, and thus improve the energy storage performance of the capacitor at high temperature.

[0025] In an optional embodiment, the thickness of the multilayer composite capacitor film is 10 μm to 30 μm;

[0026] The thickness of the single-layer inorganic thin film is 50nm to 400nm.

[0027] The present invention provides a method for preparing a multilayer composite dielectric film capacitor. The thickness of the multilayer composite capacitor film is 10 μm to 30 μm; the thickness of the single-layer inorganic film is 50 nm to 400 nm. By controlling the thickness of the inorganic film, the uniformity of the interlayer interface between the organic film and the inorganic film can be improved, thereby utilizing the interlayer interface to reduce carrier mobility, suppress low-field dielectric loss and high-field leakage loss, and improve breakdown strength and charge-discharge efficiency, thereby improving the energy storage performance of the capacitor at high temperatures.

[0028] In an optional embodiment, the vapor deposition process is a plasma enhanced chemical vapor deposition process.

[0029] The present invention provides a method for preparing a multilayer composite dielectric film capacitor, wherein an inorganic film is prepared by plasma-enhanced chemical vapor deposition (PECVD). The film deposition is completed by utilizing highly reactive chemical substances in an ionized and excited state and free radicals in a discharge region. Parameters such as the rise rate, frequency, and amplitude of the optimized microsecond pulse voltage of the PECVD process can be controlled, thereby completing rapid and stable deposition at room temperature, obtaining a dense, uniform, and high-purity inorganic film. This method avoids damage to the organic film, ensures a high energy storage density of the organic polymer film, and simultaneously ensures the uniformity of the inorganic film, thereby improving the efficiency of the preparation process and reducing the process cost.

[0030] In an optional embodiment, in the vapor deposition process, tetraethoxysilane (TEOS) is used as a deposition precursor of SiO2; the deposition rate is 1 nm / s to 2 nm / s;

[0031] After the step of forming the organic-inorganic double-layer thin film, the method further comprises:

[0032] The organic-inorganic double-layer film is subjected to a first vacuum drying process.

[0033] In an optional embodiment, before the lamination process is performed, the method further includes:

[0034] The organic-inorganic bilayer film was washed with ethanol and deionized water in sequence;

[0035] performing a second vacuum drying process on the organic-inorganic double-layer film to remove impurities in the organic-inorganic double-layer film;

[0036] The lamination process includes:

[0037] stacking a plurality of organic-inorganic bilayer films, wherein the organic film in each organic-inorganic bilayer film contacts the inorganic film in an adjacent organic-inorganic bilayer film;

[0038] Placing a plurality of stacked organic-inorganic double-layer films in a pressing mold, placing protective films on the uppermost and lowermost layers, and performing a hot pressing process;

[0039] Peel off the protective film on both sides.

[0040] In an optional embodiment, in the hot pressing process, the hot pressing temperature is 180° C. to 240° C., and the hot pressing time is 1 hour to 6 hours;

[0041] The protective film is PTFE film.

[0042] In a second aspect, the present invention provides a multilayer composite dielectric film capacitor, the multilayer composite dielectric film capacitor comprising:

[0043] A multilayer composite capacitor film comprising an organic film and an inorganic film alternately stacked; the outermost layers on both sides of the multilayer composite capacitor film are respectively a first electrode contact layer and a second electrode contact layer; the first electrode contact layer and the second electrode contact layer are both inorganic films;

[0044] The electrodes are located outside the first electrode contact layer and outside the second electrode contact layer.

[0045] The multilayer composite dielectric film capacitor provided by the present invention, on the one hand, by using a multilayer composite capacitor film of alternating organic and inorganic layers as the dielectric of the capacitor, can utilize the interlayer interface of the organic film and the inorganic film to capture carriers, thereby reducing the carrier mobility and further suppressing its high-temperature loss, thereby significantly suppressing low-field dielectric loss and high-field leakage loss, and improving the charge and discharge efficiency; at the same time, the interlayer interface can also slow down the damage of the carriers to the organic polymer molecular chain, enhancing the breakdown field strength. On the other hand, using the inorganic film as the first electrode contact layer and the second electrode contact layer can increase the charge injection barrier at the interface between the electrode and the dielectric, suppress the amount of injected charge, reduce the current conduction loss at the electrode contact interface, and improve the charge and discharge efficiency; at the same time, a shielding layer is formed between the electrode and the multiple interlayer interfaces, which can also suppress the injection of charge and suppress ions. The multilayer composite dielectric film capacitor provided by the present invention reduces the current conduction loss at the electrode contact interface, improves the breakdown strength and charge and discharge efficiency of the capacitor, thereby improving the energy storage performance of the capacitor, so that the capacitor has a higher energy storage density, lower current conduction loss and excellent energy storage characteristics at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 The figure is a flow chart of a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0048] Figure 2 It is a structural schematic diagram of forming an organic-inorganic double-layer thin film in a method for preparing a multi-layer composite dielectric thin film capacitor according to an embodiment of the present invention.

[0049] Figure 3 It is a structural schematic diagram of forming an organic film-inorganic film alternating structure in a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0050] Figure 4 It is a structural schematic diagram of forming a multilayer composite capacitor film in a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0051] Figure 5 It is a structural schematic diagram of forming electrodes in a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0052] Figure 6 It is the Schottky fitting diagram of P(VDF-HFP) organic film and P(VDF-HFP) / SiO2 multilayer composite capacitor film.

[0053] Figure 7A This is the relationship between the discharge energy density of P(VDF-HFP) and P(VDF-HFP) / SiO2-(3,5,7,9)L and the electric field at 70°C in a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0054] Figure 7B This is the relationship between the charge and discharge efficiency of P(VDF-HFP) and P(VDF-HFP) / SiO2-(3,5,7,9)L and the electric field at 70°C in a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0055] Figure 8 The figure is a schematic diagram of a specific process of a method for preparing a multilayer composite dielectric film capacitor according to an embodiment of the present invention.

[0056] Reference numerals:

[0057] 11. Organic film; 12. Inorganic film; 10. Organic-inorganic double-layer film; 100. Organic film-inorganic film alternating structure; 20. Electrode; 101. First electrode contact layer; 102. Second electrode contact layer. DETAILED DESCRIPTION

[0058] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0059] In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present invention. The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present invention. These figures are not drawn to scale; certain details are exaggerated and may be omitted for clarity. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intervening layer / element between them. Furthermore, if a layer / element is "on" another layer / element in one orientation, it may be "below" the other layer / element when the orientation is reversed.

[0060] There are various temperature-dependent conduction mechanisms in polymer dielectrics (for example, injected charge at the electrode / dielectric interface). When the ambient temperature gradually increases, these conduction mechanisms will cause the leakage current and conduction loss in the polymer dielectric to increase sharply, resulting in higher energy loss of the polymer film at high temperatures, thereby reducing the storage performance of the capacitor at high temperatures. In the related art, a multilayer polymer film with a "sandwich structure" is formed by thin film coating technology. However, in this solution, due to the low injection barrier at the contact interface between the organic polymer film and the electrode, the current leaks from the electrode to the inside of the electrical polymer film, which in turn leads to increased current conduction loss, and the capacitor has higher energy loss at high temperatures, which reduces the energy storage performance of the capacitor.

[0061] At present, thin film coating technology is mainly divided into two categories: chemical vapor deposition (CVD) and physical vapor deposition (PVD). Most CVD processes are carried out at high temperatures (above 300°C), while the melting points of most high energy storage density polymers are much lower than this temperature. For example, the melting point of P(VDF-HFP) is only ~160°C. Therefore, it is not feasible to perform CVD directly on high energy storage density polymer films. Most PVD processes usually require vacuum, cannot complete a continuous deposition process, and cannot directly form a multilayer thin film structure.

[0062] Therefore, a solution is needed to form a multilayer film structure without damaging the organic polymer film, thereby reducing the current conduction loss at the electrode contact interface while ensuring the high energy storage density of the organic polymer film, so that the capacitor has excellent energy storage characteristics at high temperatures.

[0063] like Figure 1As shown, this embodiment provides a method for preparing a multilayer composite dielectric film capacitor, which includes but is not limited to steps S101 to S105.

[0064] Step S101 : providing an organic thin film 11 .

[0065] Step S102, forming an inorganic thin film 12 on one side of the organic thin film 11 by a vapor deposition process to form an organic-inorganic double-layer thin film 10, such as Figure 2 shown.

[0066] In step S103, a plurality of organic-inorganic double-layer films 10 are laminated, wherein the organic film 11 in each organic-inorganic double-layer film 10 contacts the inorganic film 12 in the adjacent organic-inorganic double-layer film 10, forming an organic film-inorganic film alternating structure 100 in which the outermost layers on both sides are the organic film 11 and the inorganic film 12, respectively. The outermost inorganic film 12 is the first electrode contact layer 101, as shown in FIG. Figure 3 shown.

[0067] Step S104, forming an inorganic film 12 as a second electrode contact layer 102 on the outer side of the organic film 11 of the organic film-inorganic film alternating structure 100 by a vapor deposition process, forming a multilayer composite capacitor film with both outermost layers of the inorganic film 12 as the second electrode contact layer 102. Figure 4 shown.

[0068] Step S105: forming electrodes 20 on the outer sides of the first electrode contact layer 101 and the second electrode contact layer 102, respectively. Figure 5 shown.

[0069] In step S103, the number of organic-inorganic bilayer thin films 10 may be one or more. In some embodiments, a single organic-inorganic bilayer thin film 10 is subjected to a lamination process to form an organic film-inorganic film alternating structure 100 in which the outermost layers on both sides are an organic film 11 and an inorganic film 12, respectively. The outermost inorganic film 12 serves as the first electrode contact layer 101. In other embodiments, a plurality of organic-inorganic bilayer thin films 10 are subjected to a lamination process, with the organic film 11 in each organic-inorganic bilayer thin film 10 contacting the inorganic film 12 in the adjacent organic-inorganic bilayer thin film 10, to form an organic film-inorganic film alternating structure 100 in which the outermost layers on both sides are an organic film 11 and an inorganic film 12, respectively. The outermost inorganic film 12 serves as the first electrode contact layer 101.

[0070] The preparation method of the multilayer composite dielectric film capacitor provided in this embodiment includes the following steps: first, an inorganic film is formed on one surface of an organic film by a vapor deposition process, and several organic-inorganic double-layer films are pressed together to form an alternating organic film-inorganic film structure. Finally, an inorganic film is formed on the outer side of the outermost organic film as a second electrode contact layer. The inorganic film can be formed at a low temperature by the vapor deposition process, thereby avoiding damage to the organic film and ensuring the high energy storage density of the organic polymer film. At the same time, the multilayer alternating structure is formed by a lamination process, which can simplify the process flow and reduce costs. Second, by forming a multilayer composite capacitor film as the dielectric of the capacitor, the interlayer interface between the organic film and the inorganic film can be used to capture carriers, thereby reducing the carrier mobility and suppressing its high-temperature loss, thereby significantly suppressing low-field dielectric loss and high-field leakage loss, and improving the charge and discharge efficiency. At the same time, the interlayer interface can also slow down the damage of carriers to the organic polymer molecular chain and enhance the breakdown field strength. Third, using an inorganic thin film as the first and second electrode contact layers can increase the charge injection barrier at the interface between the electrode and the dielectric, suppressing the amount of injected charge, reducing current conduction losses at the electrode contact interface, and improving charge and discharge efficiency. Simultaneously, a shielding layer is formed between the electrode and the interfaces between the multiple layers, which can also suppress charge injection and ion suppression. The method for preparing a multilayer composite dielectric thin film capacitor provided by the present invention can form a multilayer film structure without damaging the organic polymer film. This reduces current conduction losses at the electrode contact interface while maintaining the high energy storage density of the organic polymer film, improving the breakdown strength and charge and discharge efficiency of the capacitor, and thus improving the energy storage performance of the capacitor, resulting in a capacitor with a high energy storage density, low current conduction losses, and excellent energy storage characteristics at high temperatures.

[0071] In some optional embodiments, the organic film 11 has a dielectric constant greater than 2 and a breakdown strength greater than 200 MV / m;

[0072] The inorganic thin film 12 has a band gap greater than 5 eV and a breakdown strength greater than 800 MV / m;

[0073] The injection barrier at the interface when the material of the inorganic thin film 12 contacts the material of the electrode is larger than the injection barrier at the interface when the material of the organic thin film 11 contacts the material of the electrode.

[0074] It should be noted that the above-mentioned “injection barrier at the contact interface when the material of the organic film contacts the material of the electrode” does not mean that the organic film contacts the electrode in the final structure. In the final structure, only the inorganic film contacts the electrode.

[0075] In some optional embodiments, the material of the organic film 11 is P(VDF-HFP), and the material of the inorganic film 12 is silicon dioxide, forming a multilayer composite capacitor film of P(VDF-HFP) / SiO2. Schottky fitting is used to verify the injection barrier at the interface between different film materials and the electrode materials.

[0076] According to the Schottky fitting theory, at high temperatures, the Schottky emission can be expressed as formula (1):

[0077]

[0078] Where E is the electric field, A is the Richardson constant, φ is the barrier height at the electrode / dielectric interface, T is the temperature, ε is the dielectric constant, and k b is the Boltzmann constant.

[0079] It can be written as formula (2):

[0080]

[0081] It can be seen that ln(J / T 2 ) and E 1 / 2 The relationship graph should show a linear relationship. 1 / 2 As the horizontal axis, ln(J / T 2 ) as the ordinate, a Schottky fit curve for the dielectric is plotted. The intercept of the ordinate in a Schottky fit plot is related to the injection barrier, with a higher intercept corresponding to a lower injection barrier. This can be used to simply compare the injection barriers of different materials.

[0082] First, a conventional P(VDF-HFP) organic film and a P(VDF-HFP) / SiO2 multilayer composite capacitor film are provided, electrodes 20 are formed on both sides of the films, and then Schottky fitting is performed. Figure 6 Figure 2 shows the Schottky fitting plots for the P(VDF-HFP) organic film and the P(VDF-HFP) / SiO2 multilayer composite capacitor film. It can be seen that the charge injection barrier height of the P(VDF-HFP) / SiO2 multilayer composite capacitor film is higher than that of the pure P(VDF-HFP) organic film (i.e., the intercept of the fitting curve is lower). This indicates that the probability of injected charge directly entering the polymer film through the SiO2 inorganic insulating layer is much lower than that of the pure P(VDF-HFP) organic film. In fact, at 70°C and 200 MV / m, the leakage current density of the pure P(VDF-HFP) organic film is approximately 20 times that of the P(VDF-HFP) / SiO2 multilayer composite capacitor film, that is, 4.46×10 -6 A / cm 2 2.23×10-7 A / cm 2 .

[0083] Fitting the current density in the Schottky plots of P(VDF-HFP) and P(VDF-HFP) / SiO2 composites confirms the increase in barrier height. A higher barrier indicates that charge is less likely to be injected from the electrode into the dielectric film (i.e., the probability is lower), resulting in lower conduction losses. These results indicate that the electrode / SiO2 contact interface effectively suppresses charge injection from the electrode compared to the electrode / P(VDF-HFP) interface. Therefore, in this study, the contact interface between the electrode and the SiO2 inorganic film was selected as the contact interface between the multilayer composite and the electrode.

[0084] The method for preparing a multilayer composite dielectric film capacitor provided in this embodiment has a greater injection barrier at the interface between the inorganic film material and the electrode material than at the interface between the organic film material and the electrode material. By selecting a wide-bandgap, high-breakdown-strength inorganic film material to coat the organic film surface, and using the inorganic film as the first and second electrode contact layers, the charge injection barrier at the interface between the electrode and the inorganic film can be increased, the amount of injected charge can be suppressed, the current conduction loss at the electrode contact interface can be reduced, the charge-discharge efficiency can be improved, and the energy storage performance of the capacitor can be improved. At the same time, the interlayer interface between the organic and inorganic films can be used to reduce carrier mobility, significantly suppress low-field dielectric loss and high-field leakage loss, and further improve breakdown strength and charge-discharge efficiency.

[0085] In some optional embodiments, the material of the organic film 11 is PVDF and its copolymers;

[0086] The material of the inorganic thin film 12 is aluminum oxide, silicon oxide or hafnium oxide;

[0087] The total number of layers of the multilayer composite capacitor film is 3 to 19 layers.

[0088] In specific implementation, PVDF (polyvinylidene fluoride) copolymers include binary copolymers and ternary copolymers. Among them, binary copolymers are obtained by introducing a bulky comonomer into PVDF. Common comonomers include chlorofluoroethylene (CFE), chlorodifluoroethylene (CDFE), chlorotrifluoroethylene (CTFE) and trifluoropropylene (TFP), hexafluoropropylene (HFP), vinyl fluoride (TrFE), and trifluoroethylene bromide (BTFE). Terpolymers are obtained by introducing two bulky comonomers into PVDF. Common comonomers include chlorofluoroethylene (CFE), chlorodifluoroethylene (CDFE), chlorotrifluoroethylene (CTFE) and trifluoropropylene (TFP), hexafluoropropylene (HFP), vinyl fluoride (TrFE), and trifluoroethylene bromide (BTFE).

[0089] In some optional embodiments, the material of the organic film 11 is P(VDF-HFP), and the material of the inorganic film 12 is silicon dioxide, forming a multilayer composite capacitor film as P(VDF-HFP) / SiO2 multilayer composite capacitor film, the thickness of each SiO2 inorganic film is 200nm, and the total number of layers is controlled to be 3 layers, 5 layers, 7 layers, and 9 layers, recorded as P(VDF-HFP) / SiO2-xL-ynm, where x is the total number of layers of the multilayer composite capacitor film, and y is the thickness of a single inorganic film.

[0090] In one example, the present invention verifies the energy storage performance of the capacitor formed when the total number of layers of the multilayer composite capacitor film is 3 layers, 5 layers, 7 layers, and 9 layers, respectively. The four films are recorded as P(VDF-HFP) / SiO2-3L, P(VDF-HFP) / SiO2-5L, P(VDF-HFP) / SiO2-7L, and P(VDF-HFP) / SiO2-8L, respectively. Energy storage performance (including discharge energy density and charge-discharge efficiency) is usually characterized by DE loops measured under various electric fields and temperatures. A modified Sawyer-Tower circuit was used to collect DE loops of P(VDF-HFP) / SiO2-(3,5,7,9)L at 70°C to study the energy storage performance (including discharge energy density and charge-discharge efficiency) of the multilayer composite material. Figure 7A and Figure 7B The discharge energy density and charge-discharge efficiency of P(VDF-HFP) and P(VDF-HFP) / SiO2-(3,5,7,9)L at 70°C are shown respectively. With the increase of the interlayer interface, the discharge energy density and charge-discharge efficiency of the multilayer composite material increased significantly, which proves the advantage of the organic / inorganic interlayer interface in improving the energy storage performance of the composite material. At 70°C, P(VDF-HFP) / SiO2-9L has the highest discharge energy density of 6.8J / cm at a breakdown electric field of about 395MV / m. 3 , compared with P(VDF-HFP) / SiO2-3L's ~4.7J / cm 3 and pure P(VDF-HFP) ~2.4J / cm 3In comparison, the improvement is about 44% and 183%, respectively. In addition, for practical applications, the charge and discharge efficiency is another key indicator of energy storage performance, which is closely related to the heat dissipation of the capacitor and affects the service life of the capacitor. Ferroelectric polymers have high loss, which leads to relatively low charge and discharge efficiency. For example, at 70°C, the charge and discharge efficiency of pure P(VDF-HFP) at 250MV / m is only ~56%. P(VDF-HFP) / SiO2-9L composed of ferroelectric polymer and inorganic insulating layer shows a charge and discharge efficiency of 78% under an electric field of 250MV / m. It can be seen that the discharge energy density and charge and discharge efficiency of P(VDF-HFP) / SiO2 multilayer composite material are significantly higher than those of pure P(VDF-HFP), which once again proves the superiority of the organic / inorganic interlayer interface in enhancing the energy storage performance of polymer dielectrics.

[0091] Therefore, as the total number of layers of the multilayer composite capacitor film increases, the discharge energy density and charge-discharge efficiency of the multilayer composite capacitor film will increase significantly. However, if the total number of layers is too high, the surface uniformity of the inorganic film after the lamination process will be reduced. Therefore, the total number of layers of the multilayer composite capacitor film is 3 to 19 layers, which can improve the discharge energy density and charge-discharge efficiency of the multilayer composite capacitor film while ensuring the surface uniformity of the inorganic film, thereby improving the energy storage performance and reliability of the capacitor.

[0092] The preparation method of the multilayer composite dielectric film capacitor provided in this embodiment, on the one hand, the PVDF copolymer has not only a high polarization strength but also a high dielectric strength, thus having a high energy storage density, which can make the capacitor have a high energy storage density. Inorganic films such as aluminum oxide, silicon oxide or hafnium oxide have a low band gap and breakdown strength. The contact interface between the inorganic film and the electrode has a high charge injection barrier, which can reduce the leakage current and conduction loss at the electrode contact interface and reduce the energy loss at high temperature, thereby making the capacitor have excellent energy storage characteristics at high temperature; on the other hand, the interlayer interface of the organic film / inorganic film can significantly suppress the low-field dielectric loss and high-field leakage loss, thereby improving the breakdown strength and charge and discharge efficiency. The total number of layers of the multilayer composite capacitor film is 3 to 19 layers, and the number of interlayer interfaces between the organic film and the inorganic film is 2 to 17, which can improve the discharge energy density and charge and discharge efficiency of the multilayer composite capacitor film while ensuring the surface uniformity of the inorganic film, thereby improving the energy storage performance and reliability of the capacitor.

[0093] In some optional embodiments, the material of the organic film 11 is P(VDF-HFP) or P(VDF-TrFE-CFE);

[0094] The material of the inorganic film 12 is silicon dioxide;

[0095] The total number of layers of the multilayer composite capacitor film is 5 to 15 layers.

[0096] In specific implementation, since the higher the number of interlayer interfaces between the organic film and the inorganic film, the higher the breakdown strength and charge-discharge efficiency, the total number of layers of the multilayer composite capacitor film is preferably greater than or equal to 5, and the higher the total number of layers, the better. If the total number of layers is too high, it may affect the uniformity of the inorganic film, and thus affect the performance of the interlayer interface. Therefore, the total number of layers of the multilayer composite capacitor film is 5 to 15 layers, which can effectively reduce the mobility of carriers, suppress low-field dielectric loss and high-field leakage loss, improve breakdown strength and charge-discharge efficiency, and thus improve the energy storage performance of the capacitor at high temperature. In one example, the material of the organic film 11 is P (VDF-HFP), and the material of the inorganic film 12 is silicon dioxide, and the multilayer composite capacitor film formed is P (VDF-HFP) / SiO2 multilayer composite capacitor film; in another example, the material of the organic film 11 is P (VDF-TrFE-CFE), and the material of the inorganic film 12 is silicon dioxide, and the multilayer composite capacitor film formed is P (VDF-TrFE-CFE) / SiO2 multilayer composite capacitor film;

[0097] The preparation method of the multilayer composite dielectric film capacitor provided in this embodiment is that the material of the organic film is P(VDF-HFP) or P(VDF-TrFE-CFE), and the material of the inorganic film is silicon dioxide. SiO2 has a wide band gap greater than 9eV and a high breakdown strength greater than 800MV / m, and can be used as an inorganic insulating layer. At the same time, the injection barrier of the contact interface when SiO2 contacts the electrode is greater than the injection barrier of the contact interface when P(VDF-HFP) or P(VDF-TrFE-CFE) contacts the electrode material. Therefore, the SiO2 inorganic film serves as the first electrode contact layer and the second electrode contact layer in contact with the electrode, which can increase the charge injection barrier at the contact interface between the electrode and the inorganic film, suppress the amount of injected charge, reduce the current conduction loss at the electrode contact interface, improve the charging and discharging efficiency, and improve the energy storage performance of the capacitor. In addition, the total number of layers of the multilayer composite capacitor film is 5 to 15 layers, and the number of interlayer interfaces between the organic film and the inorganic film is 4 to 14. The number of interlayer interfaces can reduce the mobility of carriers, significantly suppress low-field dielectric loss and high-field leakage loss, further improve the breakdown strength and charge and discharge efficiency, and thus improve the energy storage performance of the capacitor at high temperature.

[0098] In some optional embodiments, the thickness of the multilayer composite capacitor film is 10 μm to 30 μm;

[0099] The thickness of the inorganic thin film is 50 nm to 400 nm.

[0100] The present invention provides a method for preparing a multilayer composite dielectric film capacitor. The thickness of the multilayer composite capacitor film is 10 μm to 30 μm; the thickness of the single-layer inorganic film is 50 nm to 400 nm. By controlling the thickness of the inorganic film, the uniformity of the interlayer interface between the organic film and the inorganic film can be improved, thereby utilizing the interlayer interface to reduce carrier mobility, suppress low-field dielectric loss and high-field leakage loss, and improve breakdown strength and charge-discharge efficiency, thereby improving the energy storage performance of the capacitor at high temperatures.

[0101] In some optional embodiments, the material of the organic film is P(VDF-HFP), the material of the inorganic film is silicon dioxide; the thickness of the inorganic film is 200 nm; and the total number of layers of the multilayer composite capacitor film is 9.

[0102] On the one hand, the P(VDF-HFP) / SiO2 interlayer interface can significantly suppress low-field dielectric loss and high-field leakage loss, thereby improving breakdown strength and charge-discharge efficiency. On the other hand, the electrode / SiO2 is used as the contact interface to prepare multilayer composite materials with different numbers of layers, and it is determined that P(VDF-HFP) / SiO2-9L has the best energy storage performance. At 70°C, the discharge energy density of P(VDF-HFP) / SiO2-9L is about 6.8J / cm 3 , compared to P(VDF-HFP) / SiO2-3L and pure P(VDF-HFP), this represents an increase of approximately 44% and 183%, respectively. In addition to discharge energy density, P(VDF-HFP) / SiO2-9L also exhibits the highest charge and discharge efficiency. Therefore, a multilayer composite capacitor film with a total of nine layers exhibits superior energy storage performance.

[0103] In some optional embodiments, the vapor deposition process is a plasma enhanced chemical vapor deposition process.

[0104] The preparation method of the multilayer composite dielectric film capacitor provided in this embodiment prepares an inorganic film by plasma-enhanced chemical vapor deposition (PECVD). By utilizing highly reactive chemical substances in an ionized and excited state and free radicals in the discharge area to complete the film deposition, the parameters such as the rise rate, frequency, and amplitude of the optimized microsecond pulse voltage of the PECVD process can be controlled, thereby completing rapid and stable deposition at room temperature, obtaining a dense, uniform, and high-purity inorganic film, avoiding damage to the organic film, ensuring the high energy storage density of the organic polymer film, and at the same time ensuring the uniformity of the inorganic film, improving the efficiency of the preparation process, and reducing the process cost.

[0105] In some optional embodiments,

[0106] In some optional embodiments, in the vapor deposition process, tetraethoxysilane (TEOS) is used as a deposition precursor of SiO2; the deposition rate is 1 nm / s to 2 nm / s;

[0107] After the step of forming the organic-inorganic double-layer thin film 10, the method further includes:

[0108] The organic-inorganic double-layer film 10 is subjected to a first vacuum drying process.

[0109] In some embodiments, the step of performing a first vacuum drying process on the organic-inorganic double-layer film 10 includes placing the organic-inorganic double-layer film 10 in a vacuum oven at 40° C. for 48 hours.

[0110] The method for fabricating a multilayer composite dielectric film capacitor provides a method for adjusting the deposition time during the PECVD process to control the thickness of the SiO2 insulating layer. The optimal thickness of the SiO2 insulating layer was determined to be 200 nm based on both low-field and high-field dielectric storage properties.

[0111] In some optional embodiments, before the lamination process is performed, the method further includes:

[0112] The organic-inorganic bilayer film 10 is washed with ethanol and deionized water in sequence;

[0113] Performing a first vacuum drying process on the organic-inorganic double-layer film 10 to remove impurities in the organic-inorganic double-layer film 10;

[0114] The lamination process includes:

[0115] A plurality of organic-inorganic double-layer films 10 are stacked, wherein the organic film in each organic-inorganic double-layer film 10 contacts the inorganic film in the adjacent organic-inorganic double-layer film 10;

[0116] Placing a plurality of stacked organic-inorganic double-layer films 10 in a pressing mold, placing protective films on the uppermost and lowermost layers, and performing a hot pressing process;

[0117] Peel off the protective film on both sides.

[0118] In some embodiments, the step of performing a second vacuum drying process on the organic-inorganic double-layer film 10 includes placing the film in a vacuum oven at 40° C. for 12 hours.

[0119] In some optional embodiments, in the hot pressing process, the hot pressing temperature is 180° C. to 240° C., and the hot pressing time is 1 hour to 6 hours;

[0120] The protective film is PTFE film.

[0121] In specific implementation, after forming the organic-inorganic double-layer film 10, the deposited organic-inorganic double-layer film 10 is thoroughly cleaned with ethanol and deionized water and placed in a vacuum oven at 40°C for 12 hours to completely remove impurities. During the hot pressing process, the PTFE film acts as a barrier to impurities, ensuring the purity of the alternating structure of organic film and inorganic film. Afterwards, the mixed film is placed steadily on a hot plate together with the mold and hot pressed at 200°C for 1 hour. Subsequently, the sample is gradually cooled to room temperature. The PTFE films on both sides are gently peeled off to obtain a multilayer composite capacitor film.

[0122] like Figure 8 As shown, the present invention also provides a specific flow chart of a method for preparing a multilayer composite dielectric film capacitor, including but not limited to steps S201 to S210.

[0123] Step S201 : providing an organic film 11 , wherein the material of the organic film 11 is P (VDF-HFP).

[0124] In step S202, an inorganic film 12 is formed on one surface of the organic film by a vapor deposition process to form an organic-inorganic double-layer film 10. The material of the inorganic film 12 is SiO2, and the organic-inorganic double-layer film 10 is a P(VDF-HFP) / SiO2 double-layer film.

[0125] In the specific implementation, tetraethoxysilane (TEOS) was used as the deposition precursor for SiO2. The TEOS solution was heated to 60°C in an oil bath, and argon gas was introduced into the TEOS solution. The argon flow rate was controlled at ~250 mL / min. Ar gas was injected into the discharge region between the electrodes in the PECVD system. Ar gas was selected as the working gas for the dielectric barrier discharge system, and the Ar flow rate was controlled at ~2 L / min. The discharge voltage was a microsecond pulse voltage with an amplitude of ~6.4 kV, a frequency of 1.5 kHz, a pulse width of ~8 μs, and a rising edge of ~500 ns. The deposition rate was 1.54 nm / s, and the thickness of the SiO2 deposited layer was adjusted by controlling the deposition time. The deposition time was set to 0.5 min, 1 min, 2 min, 3 min, 4 min, 6 min, and 8 min, and the thicknesses of the obtained SiO2 inorganic films were 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 600 nm, and 800 nm, respectively. In one example, the thickness of the SiO2 inorganic thin film is 200 nm.

[0126] Step S203 , performing a first vacuum drying process on the organic-inorganic double-layer film 10 .

[0127] In a specific implementation, the first vacuum drying process includes placing the organic-inorganic double-layer film 10 in a vacuum oven at 40° C. for 48 hours.

[0128] Step S204 , washing the organic-inorganic double-layer film 10 with ethanol and deionized water in sequence.

[0129] In step S205 , the organic-inorganic double-layer film 10 is subjected to a second vacuum drying process to remove impurities in the organic-inorganic double-layer film 10 .

[0130] In a specific implementation, the second vacuum drying process includes: placing in a vacuum oven at 40° C. for 12 hours.

[0131] In step S206 , a plurality of organic-inorganic double-layer films 10 are stacked, with the organic film in each organic-inorganic double-layer film 10 in contact with the inorganic film in the adjacent organic-inorganic double-layer film 10 .

[0132] Step S207 , placing a plurality of stacked organic-inorganic double-layer films 10 in a pressing mold, placing protective films on the uppermost layer and the lowermost layer, and performing a hot pressing process; the protective films are PTFE films.

[0133] In a specific implementation, during the hot pressing process, the hot pressing temperature is 180° C. to 240° C., and the hot pressing time is 1 hour to 6 hours. In one example, the hot pressing temperature is 200° C., and the hot pressing time is 1 hour.

[0134] In step S208 , the protective films on both sides are peeled off to form an organic film-inorganic film alternating structure 100 , wherein the outermost layers on both sides are the organic film 11 and the inorganic film 12 , respectively. The outermost inorganic film is the first electrode contact layer 101 .

[0135] In step S209 , an inorganic film 12 is formed as a second electrode contact layer 102 on the outer side of the organic film 11 of the organic film-inorganic film alternating structure 100 by a vapor deposition process, thereby forming a multilayer composite capacitor film with the inorganic film 12 as the outermost layer on both sides.

[0136] In step S210 , electrodes 20 are formed on the outer sides of the first electrode contact layer 101 and the second electrode contact layer 102 , respectively.

[0137] In a specific implementation, gold is sprayed on the outer sides of the first electrode contact layer 101 and the second electrode contact layer 102 for 10 seconds respectively to form gold electrodes with a diameter of 1 cm.

[0138] This embodiment also provides a multilayer composite dielectric film capacitor, such as Figure 5 As shown, the multilayer composite dielectric film capacitor includes:

[0139] A multilayer composite capacitor film includes an organic film 11 and an inorganic film 12 alternately stacked; the outermost layers on both sides of the multilayer composite capacitor film are respectively a first electrode contact layer 101 and a second electrode contact layer 102; the first electrode contact layer 101 and the second electrode contact layer 102 are both inorganic films 12;

[0140] The electrodes are located outside the first electrode contact layer 101 and outside the second electrode contact layer 102 .

[0141] The multilayer composite dielectric film capacitor provided by this embodiment, on the one hand, by using the multilayer composite capacitor film of alternating organic and inorganic layers as the dielectric of the capacitor, can use the interlayer interface of the organic film and the inorganic film to capture carriers, thereby reducing the carrier mobility, thereby suppressing its high-temperature loss, thereby significantly suppressing the low-field dielectric loss and high-field leakage loss, and improving the charge and discharge efficiency; at the same time, the interlayer interface can also slow down the damage of the carrier to the organic polymer molecular chain, enhancing the breakdown field strength. On the other hand, using the inorganic film as the first electrode contact layer and the second electrode contact layer can increase the charge injection barrier at the interface between the electrode and the dielectric, suppress the amount of injected charge, reduce the current conduction loss at the electrode contact interface, and improve the charge and discharge efficiency; at the same time, a shielding layer will be formed between the electrode and the multiple interlayer interfaces, which can also suppress the injection of charge and suppress ions. The multilayer composite dielectric film capacitor provided by the present invention reduces the current conduction loss at the electrode contact interface, improves the breakdown strength and charge and discharge efficiency of the capacitor, thereby improving the energy storage performance of the capacitor, so that the capacitor has a higher energy storage density, lower current conduction loss and excellent energy storage characteristics at high temperatures.

[0142] In the description of this specification, the reference terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless otherwise clearly defined. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly defined.

[0143] While the above description does not provide detailed technical details regarding patterning and etching of each layer, those skilled in the art will appreciate that various technical means can be employed to form layers, regions, and the like in desired shapes. Furthermore, those skilled in the art may devise methods that differ from those described above to form the same structure. Furthermore, while each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously combined.

[0144] The above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and that various obvious changes, readjustments, combinations, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a multilayer composite dielectric film capacitor, characterized in that: include: providing organic thin films; forming an inorganic thin film on one surface of the organic thin film by a vapor deposition process to form an organic-inorganic double-layer thin film; laminating a plurality of the organic-inorganic bilayer films, wherein the organic film in each organic-inorganic bilayer film contacts the inorganic film in an adjacent organic-inorganic bilayer film, to form an organic film-inorganic film alternating structure in which the outermost layers on both sides are organic films and inorganic films, respectively, and the outermost inorganic film serves as a first electrode contact layer; forming an inorganic film as a second electrode contact layer on the outer side of the organic film of the outermost layer of the organic film-inorganic film alternating structure by a vapor deposition process, thereby forming a multilayer composite capacitor film in which the outermost layers on both sides are inorganic films; Electrodes are formed on the outer sides of the first electrode contact layer and the second electrode contact layer, respectively.

2. The method for preparing a multilayer composite dielectric film capacitor according to claim 1, wherein: The organic film has a dielectric constant greater than 2 and a breakdown strength greater than 200 MV / m; The inorganic film has a band gap greater than 5eV and a breakdown strength greater than 800MV / m; An injection barrier at a contact interface between the material of the inorganic thin film and the material of the electrode is greater than an injection barrier at a contact interface between the material of the organic thin film and the material of the electrode.

3. The method for preparing a multilayer composite dielectric film capacitor according to claim 2, wherein: The material of the organic film is PVDF and its copolymer; The material of the inorganic thin film is aluminum oxide, silicon oxide or hafnium oxide; The total number of layers of the multilayer composite capacitor film is 3 to 19 layers.

4. The method for preparing a multilayer composite dielectric film capacitor according to claim 3, wherein: The material of the organic film is P(VDF-HFP) or P(VDF-TrFE-CFE); The material of the inorganic thin film is silicon dioxide; The total number of layers of the multilayer composite capacitor film is 5 to 15 layers.

5. The method for preparing a multilayer composite dielectric film capacitor according to claim 1, wherein: The thickness of the multilayer composite capacitor film is 10 μm to 30 μm; The thickness of a single layer of the inorganic thin film is 50 nm to 400 nm.

6. The method for preparing a multilayer composite dielectric film capacitor according to claim 4, wherein: The vapor deposition process is a plasma enhanced chemical vapor deposition process.

7. The method for preparing a multilayer composite dielectric film capacitor according to claim 6, wherein: In the vapor deposition process, tetraethoxysilane is used as a deposition precursor of SiO2; The deposition rate is 1nm / s to 2nm / s; After the step of forming the organic-inorganic double-layer thin film, the method further comprises: The organic-inorganic double-layer film is subjected to a first vacuum drying process.

8. The method for preparing a multilayer composite dielectric film capacitor according to claim 7, wherein: Before the lamination process, it also includes: washing the organic-inorganic bilayer film with ethanol and deionized water in sequence; performing a second vacuum drying process on the organic-inorganic double-layer film to remove impurities from the organic-inorganic double-layer film; The pressing process includes: stacking a plurality of the organic-inorganic double-layer films, wherein the organic film in each organic-inorganic double-layer film contacts the inorganic film in an adjacent organic-inorganic double-layer film; Placing a plurality of stacked organic-inorganic double-layer films in a pressing mold, placing protective films on the uppermost and lowermost layers, and performing a hot pressing process; Peel off the protective film on both sides.

9. The method for preparing a multilayer composite dielectric film capacitor according to claim 8, wherein: In the hot pressing process, the hot pressing temperature is 180°C to 240°C, and the hot pressing time is 1 hour to 6 hours; The protective film is a PTFE film.

10. A multilayer composite dielectric film capacitor, characterized in that: include: A multilayer composite capacitor film comprising an organic film and an inorganic film alternately stacked; the outermost layers on both sides of the multilayer composite capacitor film are respectively a first electrode contact layer and a second electrode contact layer; the first electrode contact layer and the second electrode contact layer are both inorganic films; The electrodes are located outside the first electrode contact layer and outside the second electrode contact layer.

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