Super-tough high-strength transparent protective layer for flexible display glass and preparation method thereof

Abstract

The invention provides a bendable display device. The bendable display device is composed of a display glass panel and a transparent protective film, wherein the display glass panel comprises a plurality of layers of metal oxide nano structures and is used for displaying visual images, and the transparent protective film is deposited on the display glass panel. The bendable display device has obviously improved mechanical properties such as surface ductility, stability, bendability and the like, keeps high transmittance and transparency, and has excellent optical properties. The invention further provides a method for manufacturing the bendable display device.

Description

Technical Field

[0001] This invention relates to protective layers for displays, specifically to an ultra-tough, high-strength transparent protective layer suitable for flexible display panels and its preparation method. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are organic compounds that emit light when electricity is applied. The development of OLEDs is crucial for the emergence of flexible display technology because these compounds have inherent flexibility, while traditional light-emitting diodes are relatively rigid.

[0003] In flexible display panel materials, flexible display glass is generally defined as a bendable ultrathin glass substrate with a thickness of less than 100μm. Due to its advantages such as extremely thin thickness, small bending radius, high transmittance, and high thermal dimensional stability, it has particularly high applicability in electronic products.

[0004] In recent years, flexible display glass has gained favor in the industry and has been the subject of many advanced explorations and commercial applications. Several mobile phone manufacturers have launched foldable or rollable phones using flexible display glass, demonstrating that flexible display glass has been widely adopted, manufactured, and integrated into flexible surface electronic display technology.

[0005] However, the main drawback of flexible display glass materials is their relatively low surface ductility, meaning that the material is still prone to plastic deformation under tensile stress, which may eventually lead to fracture. In other words, optical displays using these materials may exhibit brittleness and microcracks when bent; but to prevent these phenomena, only materials with a limited bending radius can be used, making it difficult to achieve both surface ductility and mechanical strength.

[0006] More importantly, in addition to the decline in performance such as touch sensitivity, flexible display glass materials are more likely to crack at extreme bending angles, producing sharp glass fragments or debris, posing a significant safety risk to users of consumer electronics products such as smartphones and tablets.

[0007] Therefore, there is a need to develop a flexible display material with a high-strength and high-toughness protective layer to increase the surface ductility of flexible glass materials while maintaining high transparency, reasonable cost-effectiveness, and ease of mass production. This invention meets this need. Summary of the Invention

[0008] One aspect of the present invention provides a flexible display device comprising a multilayer metal oxide nanostructure configured as a display glass panel for displaying visual images, and a transparent protective film deposited on the display glass panel.

[0009] The aforementioned transparent protective film is specially designed with a thickness of less than 1000 nanometers and a light transmittance of at least 93%.

[0010] The bending display device of the present invention has a surface ductility of at least 50N and a bending radius of less than 1 mm.

[0011] In one embodiment of the first aspect of the present invention, the metal oxide in the multilayer metal oxide nanostructure is selected from indium tin oxide, aluminum-doped zinc oxide, or indium-doped cadmium oxide.

[0012] In another embodiment, the device is manufactured by depositing a transparent protective film in situ on the display glass panel.

[0013] A second aspect of the present invention also provides a method for manufacturing a flexible display device. The method includes: preparing a transparent protective layer comprising a multilayer metal oxide nanostructure; vaporizing the multilayer metal oxide nanostructure; transferring the vaporized multilayer metal oxide nanostructure onto a display glass panel; and condensing the vaporized multilayer metal oxide nanostructure on the display glass panel to form a transparent protective film on the display glass panel.

[0014] In one embodiment of the second aspect, the metal oxide in the multilayer metal oxide nanostructure is selected from indium tin oxide, aluminum-doped zinc oxide, or indium-doped cadmium oxide.

[0015] In another embodiment, the thickness of the transparent protective film is less than 1000 nanometers.

[0016] In other embodiments, the transparent protective film has a light transmittance of at least 93%.

[0017] In yet another embodiment, the flexible display device has a surface ductility of at least 50 N.

[0018] In another embodiment, the bending radius of the flexible display device is less than 1 mm. Attached Figure Description

[0019] These accompanying drawings illustrate certain embodiments to further illustrate and clarify the above and other aspects, advantages, and features of the invention. It is to be understood that these drawings depict embodiments of the invention and are not intended to limit its scope. Various aspects of the invention will be further described in detail using the accompanying drawings, wherein:

[0020] Figure 1 A schematic diagram of the multilayer nanostructure of the transparent protective layer of the present invention is provided, which consists of multiple metal oxide layers.

[0021] Figure 2A schematic diagram of the overall structure of the flexible display device of the present invention is provided, which includes a transparent protective layer, a plasma treatment layer, and an ion exchange layer, all of which are deposited on a glass substrate.

[0022] Figure 3 The UV-Vis transmission spectra of transparent MgZnCaO ceramic films on D263 and D263-CT ultrathin glasses are shown.

[0023] Figure 4 The crack initiation probability (PCI) of D263-CT ultrathin glass before and after plasma treatment and coating is shown as a function of the applied indentation load.

[0024] Figure 5 This is a schematic diagram of a pencil hardness test experiment.

[0025] Figure 6 The results of pencil hardness tests on some ultrathin glass are shown.

[0026] Figure 7 This is a schematic diagram of the steel wool test.

[0027] Figure 8 The results of the steel wool test on some ultrathin glass are shown.

[0028] Figure 9 The results of scratch tests on ultrathin glass are shown.

[0029] Figure 10 A bending experiment was conducted on the D263 series of ultrathin glasses using MgZnCaO ceramic thin films.

[0030] Figure 11 The D263 series of ultrathin glass was showcased, featuring a robust MgZnCaO ceramic film. Detailed Implementation

[0031] To address the mechanical strength and ductility issues of existing flexible display glass, and in order to improve the performance, mechanical strength, and lifespan of bendable or rollable electronic devices, this invention provides an ultra-tough, high-strength transparent protective film.

[0032] The ultra-tough and high-strength transparent protective film has a "sandwich" nanostructure composed of multiple metal oxide nanolayers. When it is deposited on a flexible display glass substrate, it can improve the surface ductility, stability and protection of the flexible display glass. At the same time, the high transparency of the protective film can minimize the optical quality loss of the flexible display glass.

[0033] The aforementioned ultra-tough and high-strength transparent protective film is specially designed to facilitate in-situ deposition onto flexible display glass using common physical vapor deposition (PVD) processes.

[0034] Through physical vapor deposition, multilayer metal oxide nanolayers can be vaporized in a vacuum chamber in a "sandwich" nanostructure and uniformly transferred onto a flexible display glass substrate. After condensation, an ultra-strong, high-strength transparent protective film is formed. Optional post-processing can be performed to further enhance the performance of the ultra-strong, high-strength transparent protective film.

[0035] By using physical vapor deposition (PVD) technology to coat a flexible display glass substrate with an ultra-tough, high-strength transparent protective film, it is possible to achieve complex multi-layer structure designs, and the coating process and design become more programmable and customizable.

[0036] Specifically, the flexible display device of the present invention is manufactured based on commercially available materials and technologies and an open material system.

[0037] The ultra-tough, high-strength transparent protective film of this invention is applicable to all flexible display glass substrates, including but not limited to Coming's Willow Glass and AGC's Dragontail. mM Or Schott's D T eco and other commercially available flexible display glass products.

[0038] Furthermore, although the ultra-tough and high-strength transparent protective film of the present invention is composed of a "sandwich" nanostructure made of multiple overlapping metal oxides, the metal oxides can be selected from commercially available and readily available materials such as indium tin oxide, aluminum-doped zinc oxide, and indium-doped cadmium oxide.

[0039] Combining the widely used physical vapor deposition coating technology in the industry, the method for manufacturing the flexible display device of the present invention has great commercial potential and industrial applicability, and can be put into mass production.

[0040] Example

[0041] This invention designs a flexible display device, which includes a display glass panel that has undergone ion exchange pretreatment. The display glass panel is made of flexible glass material that has undergone pretreatment processes such as ion exchange chemical treatment and plasma treatment.

[0042] The transparent protective film of this invention comprises a multilayer metal oxide nanostructure. Specifically, the multilayer metal oxide nanostructures are arranged in a compact laminated "sandwich" structure. This minimizes thickness while maximizing the optical performance of the display panel in terms of transmittance.

[0043] The thickness of the transparent protective film is less than 1000 nanometers. For example, to maximize the flexibility of the display device, the thickness of the protective film can be set to 500 to 750 nanometers. Alternatively, in another example, the thickness of the protective film can be set to 750 to 1000 nanometers, optimizing mechanical strength and ductility without sacrificing transmittance.

[0044] The transparent protective film of this invention has a light transmittance of at least 93%. Therefore, one example is to configure the light transmittance of the protective film to be 93% to 96% to achieve relatively low-cost production. In another example, the light transmittance of the protective film can be configured to be up to 99% to achieve optimal transparency and display clarity.

[0045] The flexible display device has a surface ductility of at least 50 N. For example, the ductility range can be from 50 N to 80 N.

[0046] The bending radius of the curved display device is less than 1 mm. For example, the bending radius can be from 0.6 mm to 0.9 mm.

[0047] Before the transparent protective film is deposited onto the display glass substrate using physical vapor deposition technology, the glass substrate needs to undergo ion exchange chemical treatment and plasma treatment.

[0048] The aforementioned ion exchange chemical treatment involves placing the glass substrate in a molten potassium salt bath at a temperature of at least 300°C, for example, in the range of 300°C to 450°C.

[0049] Plasma treatment involves pre-preparing the sputtering chamber by adjusting the sputtering power and temperature, and then simultaneously introducing argon and reactive gases to form a plasma-pretreated glass substrate for further physical vapor deposition processes.

[0050] The sputtering power of the injection chamber is adjustable from 200W to 800W. For example, the sputtering power can be adjusted from 450W to 650W.

[0051] On the other hand, the temperature of the sputtering chamber is regulated to be below 1000°C, for example, in the range of 500°C to 800°C.

[0052] The reactant gas introduced simultaneously with argon is selected from oxygen or nitrogen. Further, the partial pressure ratio of argon to reactant gas is between 60:40 and 80:20. For example, the partial pressure ratio of argon to reactant gas is selected from 70:30 to 75:25.

[0053] Figure 3The UV-Vis transmission spectra of transparent MgZnCaO ceramic films on D263 and D263-CT ultrathin glasses are shown. This result demonstrates that the prepared MgZnCaO ceramic films possess excellent UV-Vis transmittance (>93%), fully meeting the requirements of electronic devices.

[0054] Table 1 below and Figure 4 The effects of plasma treatment and nanocoating on the Vickers hardness (Hv) and crack resistance (CR) of D263-CT ultrathin glass were demonstrated. It was observed that plasma treatment combined with coating significantly improved the hardness and ductility of D263-CT ultrathin glass: the MgZnCaO ceramic film increased the surface hardness of D263-CT ultrathin glass from 7.01 GPa to 11.54 GPa. Simultaneously, the crack resistance of D263 ultrathin glass increased substantially from 53.3 N to 94.7 N.

[0055] Table 1:

[0056] See Figure 5 Pencil hardness (9B-9H) is a hardness test that determines the hardness of a coating by visual observation. The test involves pressing a pencil of a specific hardness firmly into the surface being tested at a 45° angle. The highest grade that will not permanently mark the surface is the number of marks on the pencil scale. Pencil hardness testing is one of the most widely recognized tests in the industry for evaluating coating performance.

[0057] See Figure 6 Pencil hardness tests showed that scratches were found on the surface of the original ultrathin glass at pencil scales 9B-9H (maximum scale), indicating a pencil hardness less than 9H. However, for ultrathin glass with a hard, transparent MgZnCaO ceramic film, no scratches were observed after pencil tests at scales 9B-9H, indicating a pencil hardness greater than 9H. Therefore, these results demonstrate that this hard, transparent MgZnCaO ceramic film can significantly improve the pencil scratch resistance of ultrathin glass.

[0058] See Figure 7 The steel wool test is another method for evaluating the wear resistance of coating materials during use. By applying friction or wear in a test setup, it simulates the wear conditions encountered by the coating material in real-world use. This test is crucial for the quality control and performance evaluation of coated products, such as those used in electronic displays and automotive interiors.

[0059] See Figure 8The steel wool test was conducted for 1000 cycles under a 1 kg load. After the test, some micro-scratches appeared on the original ultrathin glass surface, while no scratches were found on the ultrathin glass surface with the hard and transparent MgZnCaO ceramic film. This result indicates that the hard and transparent MgZnCaO ceramic film has good adhesion to the glass substrate. It also shows that the coating material has good wear resistance during use.

[0060] To better investigate the scratch resistance of ultrathin glass before and after coating, scratch tests were conducted to quantify its scratch performance. For example... Figure 9 The experimental results shown demonstrate that the hard and transparent MgZnCaO ceramic film improves the scratch resistance of the original D263 series ultrathin glass (from 16.05N to 17.97N).

[0061] The above test results verify that a hard and transparent MgZnCaO ceramic film can significantly improve the surface properties (hardness, crack resistance, adhesion, and abrasion resistance) of ultrathin glass. Similarly, the overall bending performance test showed that the D263 series ultrathin glass with the MgZnCaO ceramic film remained intact after 20,000 bends with a bending radius of 1 mm (see...). Figure 10 ).

[0062] Figure 11 Based on all the above test results, a hard and transparent MgZnCaO ceramic film was prepared using commercially available D263 series ultrathin glass as a substrate, so that the ultrathin glass can have all the above-mentioned ultraviolet-visible light transmittance, mechanical strength, scratch resistance, wear resistance and flexural strength.

[0063] In this specification, unless the context requires otherwise, "comprising" or "including" will be understood to include the said integers or groups of integers but not exclude any other integers or groups of integers. Furthermore, in the specification of this invention and particularly in the claims and / or paragraphs, the terms "comprising," "including," etc., may have the meanings conferred upon them under patent law; for example, they may allow elements not expressly listed but exclude elements found in the prior art or that affect the fundamental or novelty of the invention.

[0064] The terms "an aspect," "an example," and "a comparative example" used in this specification indicate that the described embodiments may include specific features, structures, or characteristics, but each embodiment does not necessarily include those specific features, structures, or characteristics. Furthermore, these phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in one embodiment, whether explicitly described or not, those skilled in the art will understand that this feature, structure, or characteristic will affect other embodiments.

[0065] Other definitions of selected terms used in this invention can be found in the detailed description of the invention and apply throughout the specification. Unless otherwise defined, all other technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0066] Those skilled in the art, upon reading this description, will recognize alternative embodiments that can be implemented without excessive experimentation or deviation from the spirit or scope of the invention. This invention is limited to the following claims, which encompass all such embodiments and modifications when viewed in conjunction with the foregoing description and drawings.

Claims

1. A flexible display device comprising a display glass panel for displaying visual images and a transparent protective film deposited on the display glass panel, characterized in that: The display glass panel includes flexible glass material; The transparent protective film comprises a multilayer metal oxide nanostructure; The thickness of the transparent protective film is less than 1000 nanometers; The light transmittance of the transparent protective film is at least 93%; The surface ductility of the flexible display device is at least 50N; as well as The bending radius of the flexible display device is less than 1 mm.

2. The flexible display device according to claim 1, characterized in that, The metal oxides in the multilayer metal oxide nanostructure are selected from indium tin oxide, aluminum-doped zinc oxide, or indium-doped cadmium oxide.

3. The flexible display device according to claim 1, characterized in that, The flexible display device is made by depositing a transparent protective film in situ on the display glass panel.

4. A method for manufacturing the flexible display device according to claim 1, characterized in that, include: Preparation of a transparent protective layer comprising a multilayer metal oxide nanostructure; Vaporize the multilayer metal oxide nanostructure; The glass substrate is subjected to ion exchange chemical treatment and plasma treatment to prepare the display glass panel; The vaporized multilayer metal oxide nanostructure is transferred onto the display glass panel; as well as The vaporized multilayer metal oxide nanostructure is condensed onto the display glass panel to form a transparent protective film.

5. The preparation method according to claim 4, characterized in that, The ion exchange chemical treatment includes placing the glass substrate in a molten potassium salt bath at a temperature of at least 300°C.

6. The preparation method according to claim 4, characterized in that, The plasma treatment includes: Adjusting the sputtering power and temperature of the sputtering chamber as a preliminary preparation; The glass substrate is placed in the pre-prepared sputtering chamber; and Argon and reactive gases are injected simultaneously to form the glass substrate that has undergone plasma pretreatment.

7. The preparation method according to claim 6, characterized in that, The reacting gas is selected from oxygen or nitrogen.

8. The preparation method according to claim 6, characterized in that, The sputtering power is selected from the range of 200W to 800W.

9. The preparation method according to claim 6, characterized in that, The partial pressure of the argon gas is 60-80%; and the partial pressure of the reactant gas is 20-40%.

10. The preparation method according to claim 6, characterized in that, The duration of the plasma treatment is from 10 minutes to 180 minutes.

11. The preparation method according to claim 6, characterized in that, The temperature in the sputtering chamber is below 1000 degrees Celsius.

12. The preparation method according to claim 4, characterized in that, The metal oxides in the multilayer metal oxide nanostructure are selected from indium tin oxide, aluminum-doped zinc oxide, or indium-doped cadmium oxide.

13. The preparation method according to claim 4, characterized in that, The thickness of the transparent protective film is less than 1000 nanometers.

14. The preparation method according to claim 4, characterized in that, The light transmittance of the transparent protective film is not less than 93%.

15. The preparation method according to claim 4, characterized in that, The surface ductility of the flexible display device is not less than 50N.

16. The preparation method according to claim 4, characterized in that, The bending radius of the flexible display device is less than 1 mm.

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