A flexible OLED screen without a substrate

Abstract

The utility model provides a kind of flexible OLED screen without substrate, including anode, cathode, active layer, first encapsulation film and second encapsulation film, wherein, active layer is arranged between the cathode and the anode, and based on the electron and hole luminescence provided by the cathode and the anode;First encapsulation film is arranged in the side of the anode opposite to the active layer;Second encapsulation film is arranged in the side of the cathode opposite to the active layer;The active layer is the symmetrical middle layer of the flexible OLED screen.The flexible OLED screen of the present disclosure discards the traditional substrate, and uses the first encapsulation film and the second encapsulation film located on both sides to encapsulate the display structure, so that the overall thickness of the OLED screen is thinner, and the tensile stress and compressive stress generated when folding are also smaller, and the active layer is located in the symmetrical middle layer of the OLED screen, and the deformation degree of the active layer is the smallest among the layers of the OLED screen, further avoiding the damage of the active layer, and thereby avoiding the damage of the OLED screen.

Description

Technical Field

[0001] This utility model belongs to the field of display devices, and specifically relates to a substrate-free flexible OLED screen. Background Technology

[0002] OLED screens are a widely used type of display device. Flexible OLED screens have been developed to be suitable for applications such as curved screens and foldable screens.

[0003] However, current flexible OLED screens generally rely on flexible OLED substrates to achieve their flexibility, which are relatively thick and have poor folding durability. After repeated folding, the light-emitting element of the OLED screen is easily damaged, which limits the further application of flexible OLED screens. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to provide a substrate-free flexible OLED screen, comprising: anode; cathode; An active layer is disposed between the cathode and the anode, and emits light based on electrons and holes provided by the cathode and the anode; A first encapsulation film is disposed on the side of the anode opposite to the active layer; The second encapsulation film is disposed on the side of the cathode opposite to the active layer; The active layer is the symmetrical intermediate layer of the flexible OLED screen.

[0005] In some embodiments, the first encapsulation film includes a polymer layer and a metal oxide layer stacked together; The second encapsulation film includes a polymer layer and a metal oxide layer stacked together.

[0006] In some embodiments, the first encapsulation film has a multilayer structure, wherein the innermost layer of the multilayer structure is a metal oxide layer, and the outermost layer of the multilayer structure is a polymer layer; and / or The second encapsulation film has a multilayer structure, wherein the innermost layer of the multilayer structure is a metal oxide layer and the outermost layer of the multilayer structure is a polymer layer.

[0007] In some embodiments, the metal oxide layer and the polymer layer are arranged alternately in the multilayer structure.

[0008] In some embodiments, the thickness of the polymer layer is greater than the thickness of the metal oxide layer.

[0009] In some embodiments, the metal oxide is deposited on the surface of the polymer layer to form the metal oxide layer, the metal oxide layer at least filling the depressions on the surface of the polymer layer to reduce surface roughness.

[0010] In some embodiments, the metal oxide layer includes multiple stacked metal oxide sublayers, each formed of a different metal oxide, so that the multiple metal oxide sublayers form a lattice complementary structure to improve the overall sealing performance of the metal oxide layer.

[0011] In some embodiments, the edges of the first encapsulation film and the second encapsulation film are joined to form a sealed structure that integrally seals the anode, the cathode and the active layer.

[0012] In some embodiments, the OLED screen further includes an adhesive, through which the first encapsulation film and the second encapsulation film are bonded.

[0013] In some embodiments, the polymer layer has a nano-honeycomb structure to enhance the folding toughness of the polymer layer. Beneficial effects

[0014] This invention provides a substrate-free flexible OLED screen that abandons the traditional substrate and uses a first encapsulation film and a second encapsulation film located on both sides to encapsulate the display structure (i.e., the active layer, anode, and cathode), making the overall thickness of the OLED screen thinner. When folded, the tensile and compressive stresses generated are also smaller, thus avoiding damage to the OLED screen caused by bending.

[0015] Furthermore, the active layer is located in the symmetrical middle layer of the OLED screen. When folding occurs, the deformation of the active layer is the smallest among all layers of the OLED screen, which further avoids damage to the active layer and thus avoids damage to the OLED screen. Attached Figure Description

[0016] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the flexible OLED screen structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the first encapsulation film according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the second encapsulation film in an embodiment of the present invention.

[0018] Figure label: 1. Anode; 2. Cathode; 3. Active layer; 4. First encapsulation film; 41. First polymer layer; 42. First metal oxide layer; 43. Second polymer layer; 44. Second metal oxide layer; 5. Second encapsulation film; 51. Third polymer layer; 52. Third metal oxide layer; 53. Fourth polymer layer; 54. Fourth metal oxide layer; 6. Hole transport layer; 7. Electron transport layer; 8. Polymer layer; 9. Metal oxide layer. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model are within the protection scope of the present utility model.

[0020] Flexible OLED screens are a type of OLED screen that can be bent and are widely used in curved screens and foldable screens.

[0021] This invention proposes a substrate-free flexible OLED screen. Figure 1 This is a schematic diagram of the flexible OLED screen structure according to an embodiment of the present invention, as shown below. Figure 1 As shown, the flexible OLED screen includes an anode 1, a cathode 2, an active layer 3, a first encapsulation film 4, and a second encapsulation film 5. The active layer 3 is disposed between the cathode 2 and the anode 1, emitting light based on electrons and holes provided by the cathode 2 and the anode 1. The first encapsulation film 4 is disposed on the side of the anode 1 opposite to the active layer 3, and the second encapsulation film 5 is disposed on the side of the cathode 2 opposite to the active layer 3. The active layer 3 is a symmetrical intermediate layer of the flexible OLED screen.

[0022] In the embodiments of this utility model, the substrate structure of traditional flexible OLED screens is abandoned. Only the first encapsulation film 4 and the second encapsulation film 5 are used to encapsulate the display structure (i.e., anode 1, cathode 2 and active layer 3), making the flexible OLED screen thinner and lighter. When bent, the flexible OLED screen generates less tensile and compressive stress. Furthermore, the active layer 3 is set as the symmetrical intermediate layer of the flexible OLED screen. When folded, the active layer 3 acts as the folding neutral layer, and its deformation is minimal, as are the compressive and tensile stresses. Thus, the flexible OLED screen can withstand larger bending angles and more bending cycles, extending the service life of the flexible OLED.

[0023] The first encapsulation film 4 and the second encapsulation film 5 can be encapsulation structures with a thickness of micrometers, so that the overall thickness of the flexible OLED screen is also maintained at the micrometer level.

[0024] Using the active layer 3 as the symmetrical intermediate layer of the flexible OLED screen does not mean that the thickness of the screen structure on both sides of the active layer 3 must be exactly the same. As long as the number of structural layers is roughly the same, the active layer 3 can also be considered as the symmetrical intermediate layer of the flexible OLED screen.

[0025] The active layer 3, also known as the light-emitting layer, is the structure in an OLED screen that directly generates light.

[0026] In some embodiments of this utility model, Figure 2 This is a schematic diagram of the structure of the first encapsulation film according to an embodiment of the present invention, as shown below. Figure 1 and Figure 2 As shown, the first encapsulation film 4 may include a polymer layer 8 and a metal oxide layer 9 stacked together. The polymer layer 8 may have water-repellent or water-resistant properties, while the metal oxide layer 9 has the effect of isolating oxygen and water vapor. Combining the two can achieve a comprehensive isolation effect against water, oxygen, and water vapor, effectively isolating the encapsulated active layer 3 from adverse external factors and extending the lifespan of the flexible OLED screen. Furthermore, both the polymer and the nanoscale metal oxide can have good bending performance.

[0027] In some embodiments of this utility model, Figure 3 This is a schematic diagram of the structure of the second encapsulation film according to an embodiment of the present invention, as shown below. Figure 1 and Figure 3 As shown, the second encapsulation film 5 may also include a polymer layer 8 and a metal oxide layer 9 stacked together.

[0028] In some embodiments of this invention, the polymer used to form the polymer layer 8 can be selected from various sources. For example, parylene-C can be used as the raw material for forming the polymer layer 8. Parylene-C is hydrophobic, and using it as the raw material for the polymer layer 8 can make the polymer layer 8 also hydrophobic, thus preventing liquid water from penetrating the first encapsulation film 4 and the second encapsulation film 5.

[0029] In some embodiments of this invention, the metal oxide used to form the metal oxide layer 9 can be selected from various sources. For example, aluminum oxide, zirconium dioxide, or hafnium dioxide can be used as the raw material for forming the metal oxide layer 9. Both aluminum oxide and zirconium dioxide have a dense structure, which can prevent the intrusion of water vapor and oxygen.

[0030] In some embodiments of this utility model, the first encapsulation film has a multilayer structure, the innermost layer of the multilayer structure is a metal oxide layer 9, and the outermost layer of the multilayer structure is a polymer layer 8.

[0031] In some embodiments of this utility model, the outermost layer of the multilayer structure is set as a polymer layer 8, which can isolate liquid water and some oxygen and water vapor from the outside. The remaining oxygen and water vapor are further isolated by the inner metal oxide layer 9. By rationally arranging the order of the metal oxide layer 9 and the polymer layer 8, a better encapsulation effect can be obtained.

[0032] In some embodiments of this utility model, the second encapsulation film has a multilayer structure, the innermost layer of the multilayer structure is a metal oxide layer 9, and the outermost layer of the multilayer structure is a polymer layer 8.

[0033] In some embodiments of this utility model, the outermost layer of the multilayer structure is set as a polymer layer 8, which can isolate liquid water and some oxygen and water vapor from the outside. The remaining oxygen and water vapor are further isolated by the inner metal oxide layer 9. By rationally arranging the order of the metal oxide layer 9 and the polymer layer 8, a better encapsulation effect can be obtained.

[0034] In some embodiments of this utility model, the innermost layer refers to the layer closest to the active layer 3 in the multilayer structure, and the outermost layer refers to the layer furthest from the active layer 3 in the multilayer structure.

[0035] In some embodiments of this invention, the metal oxide layer 9 and the polymer layer 8 are arranged alternately in the multilayer structure.

[0036] In some embodiments of this invention, the metal oxide layer 9 and the polymer layer 8 are arranged alternately to achieve an alternating composite of the encapsulation effects of the two materials, thereby obtaining a better encapsulation effect.

[0037] In some embodiments of this invention, the thickness of the polymer layer 8 is greater than the thickness of the metal oxide layer 9. This design maintains a good encapsulation effect while avoiding the metal oxide layer 9 becoming too thick and brittle, thus affecting the durability of the flexible OLED screen.

[0038] In some embodiments of the present invention, a metal oxide is deposited on the surface of the polymer layer 8 to form a metal oxide layer 9, which at least fills the depressions on the polymer surface to reduce surface roughness.

[0039] In some embodiments of this invention, the surface of the polymer layer 8, formed by processes such as deposition, is relatively rough. Depositing metal oxides onto the surface of the polymer layer 8 can fill the depressions on its surface, resulting in better surface smoothness. Light emitted from the active layer 3 can achieve higher transmittance when passing through the polymer layer 8, ensuring a good display effect.

[0040] Deposition is a relatively mature process, and different deposition processes can be selected depending on the material. For example, atomic layer deposition can be used for metal oxides, while chemical vapor deposition can be used for polymers.

[0041] Furthermore, although the flexible OLED screen of this invention does not use a substrate structure, a substrate structure is still required during the fabrication process. Specifically, in the fabrication of the first encapsulation film 4 and the second encapsulation film 5, a polymer needs to be deposited onto the surface of a substrate (such as a glass substrate) using a chemical vapor deposition process. After the polymer is deposited and formed into a polymer layer 8, a metal oxide layer 9 is formed on the surface of the polymer layer 8 using an atomic layer deposition process. One side of the polymer layer 8 is in direct contact with the substrate, resulting in a relatively smooth surface. While the other side of the polymer layer 8 will have a less smooth and uneven surface, the metal oxide layer 9 deposited on this side can fill in the unevenness of the surface. This not only increases the bonding effect between the polymer layer 8 and the metal oxide layer 9 through the combination of uneven surfaces, but also avoids low light transmittance caused by low smoothness, thereby improving the light transmittance of the first encapsulation film 4 and the second encapsulation film 5.

[0042] In some embodiments of this invention, the thickness of the polymer layer 8 can be in the micrometer range, for example, 2 to 4 micrometers. The thickness of the metal oxide can be in the nanometer range, for example, 20 to 100 nanometers.

[0043] In some embodiments of this utility model, the metal oxide layer 9 includes multiple stacked metal oxide sublayers, each of which is formed by different metal oxides, so that the multiple metal oxide sublayers form a lattice complementary structure to improve the overall sealing performance of the metal oxide layer 9.

[0044] In the embodiments of this invention, different metal oxides have different crystal lattice structures, and different crystal lattice structures also have different transmittance and transmission characteristics. By using different metal oxides to form stacked oxide sublayers, the transmission characteristics of multiple metal oxides can be combined to achieve a better sealing effect.

[0045] In some embodiments of this invention, the metal oxide sublayer may include an aluminum oxide layer and a hafnium dioxide layer, and the alternation of their lattices reduces pinhole defects and improves the water and oxygen barrier efficiency.

[0046] In some embodiments of this invention, the same metal oxide sublayer can be formed by a single metal oxide or by a mixture of multiple metal oxides.

[0047] In some embodiments of this utility model, the edges of the first encapsulation film 4 and the second encapsulation film 5 are joined to form a sealed structure that seals the anode 1, the cathode 2 and the active layer 3 as a whole.

[0048] In some embodiments of this utility model, the edges of the first encapsulation film 4 and the second encapsulation film 5 are combined to form a "pocket" structure, which fully encapsulates the cathode 2, the active layer 3 and the anode 1 inside, and fully seals the plane and edges of the active layer 3 to avoid damage to the active layer 3.

[0049] In some embodiments of this invention, the OLED screen may further include an adhesive, and the first encapsulation film 4 and the second encapsulation film 5 are bonded together by the adhesive.

[0050] In the embodiments of this utility model, an adhesive is used to connect the first encapsulation film 4 and the second encapsulation film 5, which makes the operation more convenient. In addition, the adhesive itself has a certain space-filling effect, which enhances the sealing effect on the active layer 3.

[0051] In some embodiments of this utility model, the adhesive can be nano-silver paste, and the edges of the first encapsulation film 4, the edges of the second encapsulation film 5, and the nano-silver paste are melted using heating technology (such as laser heating technology) to form an alloyed sealing strip.

[0052] In some embodiments of this invention, the edges of the first encapsulation film 4 and the second encapsulation film 5 can also be joined in other ways, for example, by using an adhesive with adhesive properties as a bonding agent, and using the adhesive itself to achieve the bonding.

[0053] In some embodiments of this invention, the polymer layer 8 has a nano-honeycomb structure to enhance the folding toughness of the polymer layer 8.

[0054] In the embodiments of this utility model, the polymer layer 8 needs to bend along with the entire flexible OLED screen. The nano-honeycomb structure in the polymer layer 8 can increase the bending toughness of the polymer layer 8, so as to avoid fatigue fracture of the polymer layer 8 when bending.

[0055] In some embodiments of this invention, the nanocellular structure has microchannels into which a thermally conductive liquid is injected to conduct heat from the active layer 3. The thermally conductive liquid may be silicone oil.

[0056] In some embodiments of this utility model, such as Figures 1 to 3As shown, the flexible OLED screen includes a first encapsulation film 4, an anode 1, a hole transport layer 6, an active layer 3, an electron transport layer 7, a cathode 2, and a second encapsulation film 5 arranged sequentially. The anode 1, hole transport layer 6, active layer 3, electron transport layer 7, and cathode 2 together form the basic light-emitting structure of the flexible OLED screen. The first encapsulation film 4 and the second encapsulation film 5 encapsulate the structure including the anode 1, hole transport layer 6, active layer 3, electron transport layer 7, and cathode 2, thus protecting the light-emitting structure. This eliminates the need for a traditional substrate structure, making the flexible OLED screen thinner and lighter, and resulting in lower overall tensile and compressive stresses during bending. Furthermore, the active layer 3 is located in the symmetrical middle layer of the flexible OLED screen, with the structures on both sides of the active layer 3 being basically symmetrical (one side consists of the first encapsulation film 4, anode 1, and hole transport layer 6, and the other side consists of the second encapsulation film 5, cathode 2, and electron transport layer 7). When the flexible OLED screen is bent, the active layer 3 is located on the neutral surface of the bend, and the tensile and compressive stresses it bears are very small, making it less prone to damage due to bending.

[0057] In some embodiments of this utility model, the first encapsulation film 4 and the second encapsulation film 5 have similar structures. For example, from the outer layer to the inner layer, a polymer layer 8, a metal oxide layer 9, a polymer layer 8, and a metal oxide layer 9 are sequentially disposed.

[0058] In some embodiments of this utility model, such as Figure 2 As shown, the first encapsulation film 4 includes a first polymer layer 41, a first metal oxide layer 42, a second polymer layer 43, and a second metal oxide layer 44, arranged sequentially from the outside to the inside. The first polymer layer 41 is made of parylene-C, the first metal oxide layer 42 is a nanolayer (i.e., metal oxide sublayer) of alternating aluminum oxide and zirconium dioxide, the second polymer layer 43 is made of parylene-C, and the second metal oxide layer 44 is made of aluminum oxide.

[0059] In some embodiments of this utility model, such as Figure 3 As shown, the second encapsulation film 5 includes a third polymer layer 51, a third metal oxide layer 52, a fourth polymer layer 53, and a fourth metal oxide layer 54, arranged sequentially from the outside to the inside. The third polymer layer 51 is made of parylene-C, the third metal oxide layer 52 is a nanolayer of alternating aluminum oxide and zirconium dioxide (i.e., a metal oxide sublayer), the fourth polymer layer 53 is made of parylene-C, and the fourth metal oxide layer 54 is a nanolayer of alternating aluminum oxide and zirconium dioxide (i.e., a metal oxide sublayer).

[0060] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A substrate-free flexible OLED screen, characterized in that, include: anode; cathode; An active layer is disposed between the cathode and the anode, and emits light based on electrons and holes provided by the cathode and the anode; A first encapsulation film is disposed on the side of the anode opposite to the active layer; The second encapsulation film is disposed on the side of the cathode opposite to the active layer; The active layer is the symmetrical intermediate layer of the flexible OLED screen.

2. The flexible OLED screen according to claim 1, characterized in that, The first encapsulation film includes a polymer layer and a metal oxide layer stacked together; The second encapsulation film includes a polymer layer and a metal oxide layer stacked together.

3. The flexible OLED screen according to claim 2, characterized in that, The first encapsulation film has a multilayer structure, wherein the innermost layer of the multilayer structure is a metal oxide layer, and the outermost layer of the multilayer structure is a polymer layer; and / or The second encapsulation film has a multilayer structure, wherein the innermost layer of the multilayer structure is a metal oxide layer and the outermost layer of the multilayer structure is a polymer layer.

4. The flexible OLED screen according to claim 3, characterized in that, In the multilayer structure, the metal oxide layer and the polymer layer are arranged alternately.

5. The flexible OLED screen according to any one of claims 2-4, characterized in that, The thickness of the polymer layer is greater than the thickness of the metal oxide layer.

6. The flexible OLED screen according to claim 5, characterized in that, The metal oxide is deposited on the surface of the polymer layer to form the metal oxide layer, which at least fills the depressions on the surface of the polymer layer to reduce surface roughness.

7. The flexible OLED screen according to any one of claims 2-4, characterized in that, The metal oxide layer comprises multiple stacked metal oxide sublayers, each formed by a different metal oxide, thereby creating a lattice complementary structure among the multiple metal oxide sublayers to improve the overall sealing performance of the metal oxide layer.

8. The flexible OLED screen according to any one of claims 1-4, characterized in that, The edges of the first encapsulation film and the second encapsulation film are joined to form a sealed structure that seals the anode, the cathode and the active layer as a whole.

9. The flexible OLED screen according to claim 8, characterized in that, The OLED screen also includes an adhesive, through which the first encapsulation film and the second encapsulation film are bonded together.

10. The flexible OLED screen according to any one of claims 2-4, characterized in that, The polymer layer has a nano-honeycomb structure to enhance its folding toughness.

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