Amorphous regulated high-performance inorganic high-barrier coating and preparation method thereof

Abstract

The invention belongs to the field of inorganic thin film materials, and particularly relates to an amorphous regulated high-performance inorganic high-barrier coating and a preparation method thereof. The preparation method comprises the following steps: sequentially depositing an Al2O3 / ZnO / Al2O3 three-layer structure on a flexible substrate such as PET (Polyethylene Terephthalate) by adopting a magnetron sputtering technology at room temperature, and applying proper bias voltage in the deposition process of each layer so as to improve the density of the film and form an amorphous-crystal interpenetrating layered structure; the water vapor transmission rate (WVTR) of the coating obtained through optimization under the condition of 38 DEG C / 90% RH is as low as 5.3 * 10 <-3 > g / (m < 2 >. Day), the performance is improved by 32 times compared with that of an unbiased multi-layer structure, the service life of a device is prolonged, and the high-barrier packaging requirement of electronic devices such as a flexible thin film solar cell is met.

Description

Technical Field

[0001] This invention belongs to the field of inorganic thin film materials, specifically relating to an amorphous controlled high-performance inorganic high-barrier coating and its preparation method. Background Technology

[0002] With the development of flexible electronic devices, the requirements for the barrier performance of protective films are becoming increasingly stringent. Traditional single inorganic films such as ZnO and Al2O3 have certain barrier properties, but they have shortcomings: although the amorphous Al2O3 film prepared by magnetron sputtering has a dense structure and extremely low permeability, it is brittle and prone to microcracks during bending or thermal expansion and contraction; while ZnO films often grow in a columnar crystalline shape, and the grain boundaries and inter-column voids can easily form permeation channels, weakening the overall barrier effect.

[0003] To improve barrier efficiency, the industry often uses multilayer composite structures for encapsulation, such as depositing alternating Al2O3 and ZnO layers on PET. Although the Al2O3 / ZnO multilayer structure prepared in the existing technology can improve barrier performance, the synergistic mechanism between the amorphous and crystalline layers is unclear. The influence of amorphous thickness on interface bonding and barrier efficiency lacks systematic optimization. Therefore, the amorphous layer does not effectively suppress the propagation of grain boundary dislocations, and the nanostructure distribution of the crystalline layer is uneven, resulting in poor interfacial bonding of the composite coating and poor barrier performance. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides an amorphous controlled high-performance inorganic high-barrier coating with a flexible substrate as the base. The amorphous controlled high-performance inorganic high-barrier coating includes an amorphous layer and a crystalline layer. The amorphous layer is composed of Al2O3, and the crystalline layer is composed of ZnO. An interpenetrating structure is formed between the amorphous layer and the crystalline layer.

[0005] Furthermore, the amorphous layer and the crystalline layer are obtained by deposition using a method including magnetron sputtering; the amorphous layer includes amorphous layer a and amorphous layer b; with the flexible substrate as the base, the amorphous-controlled high-performance inorganic high-barrier coating includes, from bottom to top, the amorphous layer a, the crystalline layer and the amorphous layer b.

[0006] Accordingly, the present invention also provides a method for preparing an amorphous controlled high-performance inorganic high-barrier coating as described above, wherein the magnetron sputtering conditions include using a bias voltage; the bias voltage is a negative bias voltage.

[0007] Furthermore, the preparation method of the amorphous controlled high-performance inorganic high-barrier coating includes the following steps: Step 1: Perform plasma pretreatment on the flexible substrate to obtain a pretreated substrate; Step 2: Deposit the amorphous layer a on the pretreated substrate using the magnetron sputtering method; Step 3: Deposit the crystalline layer on the amorphous layer a using the magnetron sputtering method; Step 4: Deposit the amorphous layer b on the crystalline layer using the magnetron sputtering method.

[0008] Further, in step 2, the bias voltage is -50 V; in step 3, the bias voltage is -50 V; in step 4, the bias voltage is -50 V.

[0009] Furthermore, the thickness of the amorphous high-performance inorganic high-barrier coating is 60–100 nm.

[0010] Furthermore, the thickness of the amorphous layer a is 20–50 nm, the thickness of the amorphous layer b is 20–50 nm, and the thickness of the crystalline layer is 20–60 nm.

[0011] Furthermore, in steps 2 and 4, the sputtering source used for magnetron sputtering includes an alumina target; in steps 2 and 4, the conditions for magnetron sputtering include: RF power of 100-150 W, argon flow rate of 10-20 SCCM, working pressure of 0.2-0.5 Pa, and sputtering time of 30 minutes.

[0012] Furthermore, in step 3, the sputtering source used for magnetron sputtering includes a zinc oxide target; in step 3, the conditions for magnetron sputtering include: radio frequency power of 80-120 W, argon flow rate of 10-20 SCCM, working pressure of 0.2-0.5 Pa, and sputtering time of 20 minutes.

[0013] Furthermore, the magnetron sputtering temperatures in step 1, step 2, and step 3 are all at room temperature.

[0014] Further, step 1 specifically includes placing the flexible substrate in a vacuum chamber, heating it, and then introducing argon gas (Ar gas) to perform the plasma pretreatment to obtain the pretreated substrate.

[0015] Furthermore, the flexible substrate is made of one or more of PET, PEN, PES, PDMS, and flexible glass. Furthermore, in step 1, the heating temperature is 50–70°C.

[0016] Furthermore, in step 1, the purpose of heating is to remove moisture.

[0017] Furthermore, in step 1, the flow rate of the argon gas includes 120 SCCM.

[0018] This invention employs magnetron sputtering technology to sequentially deposit a three-layer structure of Al2O3 / ZnO / Al2O3 on a flexible substrate. Simultaneously, an appropriate bias voltage is applied during the deposition of each layer to improve the film density and form an "amorphous-crystalline interpenetrating layered structure". The optimized amorphous controlled high-performance inorganic high-barrier coating has low water vapor permeability and high reliability.

[0019] Compared with the prior art, implementing the present invention has the following beneficial effects: 1. The preparation method of the present invention applies a certain negative bias voltage during the deposition process of each layer, so that the Al2O3 / ZnO / Al2O3 composite film prepared by this method forms an interpenetrating structure (uniform layered hybrid interface) in which ZnO nanocrystals are embedded in the amorphous Al2O3 matrix between the amorphous and crystalline structures, and significantly improves the film density.

[0020] 2. The overall thickness of the amorphous controlled high-performance inorganic high-barrier coating of this invention can be controlled within the range of 60–100 nm, and the water vapor permeability is as low as 5.3 × 10⁻⁶. -3 g / (m 2 It has excellent barrier properties, which are significantly better than traditional single-layer metal oxide films, and also better than coatings made by methods that do not use bias voltage or use excessively high bias voltage. It is suitable for high-reliability packaging of various flexible substrates.

[0021] 3. The present invention provides an amorphous controlled high-performance inorganic high-barrier coating in which an interpenetrating structure is formed between the amorphous layer and the crystalline layer. Al2O3 fills the gaps between ZnO grain boundaries to block the diffusion path of water molecules. At the same time, ZnO grains anchor the Al2O3 amorphous network to inhibit crack propagation. The amorphous Al2O3 layer and the polycrystalline ZnO layer have a synergistic effect, which significantly improves the barrier performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the amorphous high-performance inorganic barrier coating of Embodiment 1 of the present invention; Figure 2 This is a SEM image of the amorphous high-performance inorganic high-barrier coating of Example 1; Figure 3 SEM image of the amorphous regulated coating in Comparative Example 3; Figure 4 SEM image of the amorphous regulated coating in Comparative Example 4; Figure 5 The images shown are transmission electron microscope images of the amorphous controlled high-performance inorganic high-barrier coating from Example 1, with the left image being... Figure 5 (a) TEM image, right is Figure 5 (b) HRTEM image. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Example 1 This embodiment provides a method for preparing an amorphous controlled high-performance inorganic high-barrier coating, the steps of which are as follows: Step 1. Place the PET substrate (100μm thick) in a vacuum chamber, heat it to 60℃ to remove moisture, and then pass Ar gas (120 SCCM) through it for plasma pretreatment cleaning. Step 2. Deposit the first layer, Al2O3, on the substrate pretreated in Step 1: RF power 120 W, Ar flow rate 15 SCCM, working pressure 0.3 Pa, bias voltage -50 V, sputtering time 30 minutes; Step 3. Deposit a second ZnO layer: RF power 100 W, Ar flow rate 10 SCCM, operating pressure 0.4 Pa, bias voltage -50 V, sputtering time 20 minutes; Step 4. Deposit a third layer of Al2O3: Parameters are the same as in Step 2, to obtain an amorphous, high-performance inorganic high-barrier coating. A schematic diagram of its structure is shown below. Figure 1 (Amorphous Al2O3 layer / Polycrystalline ZnO layer / Amorphous Al2O3 layer).

[0025] Comparative Example 1 This comparative example provides a method for preparing an amorphous controlled coating, the steps of which are as follows: Step 1. Pretreatment of the PET matrix is ​​the same as step 1 in Example 1; Step 2. Deposit a ZnO layer on the pretreated substrate from Step 1: RF power 100 W, Ar flow rate 10 SCCM, working pressure 0.3 Pa, bias voltage -50 V, sputtering time 50 minutes to obtain an amorphous control coating (polycrystalline ZnO layer).

[0026] Comparative Example 2 This comparative example provides a method for preparing an amorphous controlled coating, the steps of which are as follows: Step 1. Pretreatment of the PET matrix is ​​the same as step 1 in Example 1; Step 2. Deposit an Al2O3 layer on the pretreated substrate from Step 1: RF power 120 W, Ar flow rate 10 SCCM, working pressure 0.4 Pa, bias voltage -50 V, sputtering time 100 minutes to obtain an amorphous control coating (amorphous Al2O3 layer).

[0027] Comparative Example 3 This comparative example provides a method for preparing an amorphous controlled coating, the steps of which are as follows: Step 1. Pretreatment of the PET matrix is ​​the same as step 1 in Example 1; Step 2. Deposit the first layer, Al2O3, on the substrate pretreated in Step 1: RF power 120 W, Ar flow rate 15 SCCM, working pressure 0.3 Pa, no bias voltage applied, sputtering time 30 minutes; Step 3. Deposit a second ZnO layer: RF power 100 W, Ar flow rate 10 SCCM, operating pressure 0.4 Pa, no bias voltage applied, sputtering time 20 minutes; Step 4. Deposit a third layer of Al2O3: Parameters are the same as in Step 2, to obtain an amorphous control coating (amorphous Al2O3 layer / polycrystalline ZnO layer / amorphous Al2O3 layer).

[0028] Comparative Example 4 This comparative example provides a method for preparing an amorphous controlled coating, the steps of which are as follows: Step 1. Pretreatment of the PET matrix is ​​the same as step 1 in Example 1; Step 2. Deposit the first layer, Al2O3, on the substrate pretreated in Step 1: RF power 120 W, Ar flow rate 10 SCCM, working pressure 0.4 Pa, bias voltage -60 V, sputtering time 30 minutes; Step 3. Deposit a second ZnO layer: RF power 100 W, Ar flow rate 10 SCCM, operating pressure 0.4 Pa, bias voltage -50 V, sputtering time 20 minutes; Step 4. Deposit a third layer of Al2O3: Parameters are the same as in Step 2, to obtain an amorphous control coating (amorphous Al2O3 layer / polycrystalline ZnO layer / amorphous Al2O3 layer).

[0029] The amorphous high-performance inorganic high-barrier coating in Example 1 and the amorphous control coating in the comparative example do not contain a substrate.

[0030] Example of effect 1 The amorphous high-performance inorganic high-barrier coating prepared in Example 1 and the amorphous controlled coatings prepared in Comparative Examples 1-4 were used as samples. The total thickness of the samples was measured using a surface profilometer, and the water vapor transmission rate (WVTR) was tested using a water vapor transmission rate tester at 38°C and 90% relative humidity. The results are listed in Table 1.

[0031] Table 1

[0032] As can be seen from the results in Table 1: 1) The amorphous controlled high-performance inorganic high-barrier coating of the present invention (Example 1) has an overall thickness that can be controlled to 100 nm, and a water vapor permeability as low as 5.3 × 10⁻⁶. -3 g / (m 2 ·day); 2) The amorphous control coating with a single ZnO layer (Comparative Example 1) or the amorphous control coating with a single Al2O3 layer (Comparative Example 2) has a total thickness that is comparable to or only slightly thicker than that of Example 1, but its WVTR is much higher than that of Example 1 by at least two orders of magnitude. The WVTR of the amorphous control coating with a single ZnO layer (Comparative Example 1) is even more than 300 times that of Example 1. 3) Even when the structure is similar to that of Example 1, which is “amorphous Al2O3 layer / polycrystalline ZnO layer / amorphous Al2O3 layer”, when no bias voltage is applied to each layer during magnetron sputtering (Comparative Example 3), the total thickness is significantly thicker than that of Example 1, and its WVTR is two orders of magnitude higher than that of Example 1. However, when the bias voltage of the first and third Al2O3 layers during magnetron sputtering is -60V (Comparative Example 4), the total thickness is comparable to that of Example 1, but its WVTR is still one order of magnitude higher than that of Example 1.

[0033] Example 2 The amorphous high-performance inorganic high-barrier coating prepared in Example 1, and the amorphous controlled coatings prepared in Comparative Examples 3 and 4 were used as samples. SEM images were obtained for each sample, and are shown in the figures below. Figure 2 , Figure 3 , Figure 4 .Depend on Figure 2 It can be observed that in the coating of Example 1, the interfaces between each layer are clear and straight, the overall structure is dense, and there are no visible interface defects; Figure 3 It can be observed that in the coating of Comparative Example 3, the interfaces between layers are unclear, and some pores and cracks exist; Figure 4 It can be clearly seen that in the coating of Comparative Example 4, the interlayer interface has a tooth-like morphology, and there are gaps between Al2O3 and ZnO layers.

[0034] The amorphous high-performance inorganic high-barrier coating prepared in Example 1 was used as a sample, and TEM and HRTEM images were obtained, as shown in the figures below. Figure 5 (a), (b) Figure 5 The high-resolution image corresponding to the location marked by the red circle in the TEM image of (a) can be found in [link to image]. Figure 5 (b) HRTEM plot. In Figure 5 (a) The amorphous region shown in red circles contains a large number of nanoparticles, which can be obtained from... Figure 5 (b) The magnified image shows a distinct interspaced lattice, indicating that ZnO nanocrystals are precipitated and embedded in the amorphous Al2O3 matrix, forming an interpenetrating interface. Figure 5 (b) The location circled in red.

[0035] In summary, in the amorphous controlled high-performance inorganic high-barrier coating of the present invention (Example 1), an interpenetrating structure is formed between the crystalline layer and the amorphous layer, and the interfaces between each layer are clear and the coating structure is dense. If the preparation method of the amorphous controlled high-performance inorganic high-barrier coating of the present invention is used, but without applying a bias voltage (Comparative Example 3) or with a higher bias voltage (Comparative Example 4), the interfaces between each layer of the obtained coating are unclear and have defects.

[0036] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An amorphous, high-performance inorganic high-barrier coating, characterized in that, Using a flexible substrate as a base, the amorphous controlled high-performance inorganic high-barrier coating includes an amorphous layer and a crystalline layer; the amorphous layer is composed of Al2O3, and the crystalline layer is composed of ZnO; an interpenetrating structure is formed between the amorphous layer and the crystalline layer.

2. The amorphous high-performance inorganic high-barrier coating according to claim 1, characterized in that, The amorphous layer and the crystalline layer are obtained by deposition using a method including magnetron sputtering; the amorphous layer includes amorphous layer a and amorphous layer b; with the flexible substrate as the base, the amorphous-controlled high-performance inorganic high-barrier coating includes, from bottom to top, the amorphous layer a, the crystalline layer and the amorphous layer b.

3. A method for preparing an amorphous controlled high-performance inorganic high-barrier coating as described in claim 2, characterized in that, The conditions for magnetron sputtering include the use of a bias voltage; the bias voltage is a negative bias voltage.

4. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 3, characterized in that, Includes the following steps: Step 1: Perform plasma pretreatment on the flexible substrate to obtain a pretreated substrate; Step 2: Deposit the amorphous layer a on the pretreated substrate using the magnetron sputtering method; Step 3: Deposit the crystalline layer on the amorphous layer a using the magnetron sputtering method; Step 4: Deposit the amorphous layer b on the crystalline layer using the magnetron sputtering method.

5. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, In step 2, the bias voltage is -50 V; in step 3, the bias voltage is -50 V; in step 4, the bias voltage is -50 V.

6. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, The thickness of the amorphous high-performance inorganic high-barrier coating is 60–100 nm.

7. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, In steps 2 and 4, the sputtering source used for magnetron sputtering includes an alumina target; in steps 2 and 4, the conditions for magnetron sputtering include: RF power of 100-150 W, argon flow rate of 10-20 SCCM, working pressure of 0.2-0.5 Pa, and sputtering time of 30 minutes.

8. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, In step 3, the sputtering source used for magnetron sputtering includes a zinc oxide target; in step 3, the conditions for magnetron sputtering include: radio frequency power of 80-120 W, argon flow rate of 10-20 SCCM, working pressure of 0.2-0.5 Pa, and sputtering time of 20 minutes.

9. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, Step 1 specifically includes placing the flexible substrate in a vacuum chamber, heating it, and then introducing argon gas to perform the plasma pretreatment to obtain the pretreated substrate.

10. The method for preparing the amorphous controlled high-performance inorganic high-barrier coating according to claim 4, characterized in that, The flexible substrate is made of one or more of PET, PEN, PES, PDMS, and flexible glass.

Images