Flexible display device and display panel

Abstract

The invention relates to the technical field of display, and particularly provides a flexible display device and a display panel. A second electrode; the light-emitting units are sequentially stacked between the first electrode and the second electrode, each light-emitting unit comprises a hole transport layer, a light-emitting layer and an electron transport layer which are sequentially stacked in the direction away from the first electrode, and a charge generation layer is arranged between every two adjacent light-emitting units. Wherein one or more of the electron transport layer, the charge generation layer and the hole transport layer between the adjacent light-emitting layers are of stretchable structures; the orthographic projections of the structures of the display devices respectively connected to the two sides of the stretchable structure on the substrate are at least partially not overlapped. The device provided by the invention can still keep relatively low granular sensation in a stretching state, and can provide a high-quality image display effect.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and particularly provides a flexible display device and a display panel. Background Art

[0002] As a medium for information interaction between humans and electronic devices, a display is an important part of modern electronic devices. In the application market, most electronic devices, such as mobile phones and televisions, use rigid flat display screens; some electronic devices, such as smart watches and folding mobile phones, use flexible display screens that can be bent and folded. However, neither rigid nor flexible displays can achieve tensile deformation, which severely limits the application of displays in related fields such as stretchable and wearable devices.

[0003] The difference between the stacked OLED device structure and the single-layer device lies in that a hole transport layer or an electron transport layer is added between the anode or cathode of the device and the light-emitting layer. After adding the hole (or electron) transport layer, not only can the barrier for injecting holes or electrons from the metal electrode be effectively reduced, solving the problem of unbalanced carrier injection in the single-layer device; but also the migration of carriers through this layer towards the electrode direction can be blocked, enabling exciton recombination to occur near the heterojunction interface and improving the light-emitting efficiency of the device.

[0004] In the field of traditional stretchable display devices, the commonly used method is to achieve stretchable display by setting stretchable wires. However, this design method brings some problems while realizing the stretching function. Specifically, when the device is stretched, the pixel graininess becomes more obvious, and at the same time, the image will also show a certain degree of distortion.

[0005] In view of the above problems, there is a current need to develop a more practical and efficient stretchable display device in various application scenarios. Such a device should be able to maintain a low graininess in the stretched state and provide high-quality image display effects. Summary of the Invention

[0006] In order to overcome the above defects, the present invention provides a flexible display device and a display panel that can still maintain a low graininess in the stretched state and provide high-quality image display effects.

[0007] In a first aspect, the present invention provides a flexible display device, comprising:

[0008] A first electrode;

[0009] A second electrode; and

[0010] A plurality of light-emitting units are sequentially stacked between the first electrode and the second electrode. Each light-emitting unit includes a hole transport layer, a light-emitting layer, and an electron transport layer that are sequentially stacked in a direction away from the first electrode. A charge generation layer is provided between adjacent light-emitting units. One or more of the electron transport layer, the charge generation layer, and the hole transport layer between adjacent light-emitting layers is a stretchable structure;

[0011] The orthographic projections of the structures of the display device respectively connected to both sides of the stretchable structure on the substrate at least partially do not overlap.

[0012] Further, the device includes a first light-emitting unit and a second light-emitting unit; wherein, the first light-emitting unit is closer to the first electrode than the second light-emitting unit;

[0013] In a direction away from the first electrode, the first light-emitting unit includes a first hole transport layer, a first light-emitting layer, and a first electron transport layer that are sequentially stacked;

[0014] In a direction away from the first electrode, the second light-emitting unit includes a second hole transport layer, a second light-emitting layer, and a second electron transport layer that are sequentially stacked;

[0015] The charge generation layer is provided between the first electron transport layer and the second hole transport layer.

[0016] Further, the device further includes a first insulating layer and a second insulating layer for making the orthographic projections of the structures of the display device respectively connected to both sides of the stretchable structure on the substrate at least partially non-overlapping; wherein, the first insulating layer is connected to the structure of the display device connected to one side of the stretchable structure, and the second insulating layer is connected to the structure of the display device connected to the other side of the stretchable structure.

[0017] Further, the stretchable structure includes a first electron transport layer, a charge generation layer, and a second hole transport layer;

[0018] The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, and the first light-emitting layer;

[0019] The second insulating layer is respectively connected to the same side of the second light-emitting layer, the second electron transport layer, and the second electrode.

[0020] Further, the stretchable structure includes a first electron transport layer;

[0021] The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, and the first light-emitting layer;

[0022] The second insulating layer is connected to the same side of the charge generation layer, the second hole transport layer, the second light-emitting layer, the second electron transport layer, and the second electrode, respectively.

[0023] Further, the stretchable structure includes a second hole transport layer;

[0024] The first insulating layer is connected to the same side of the first electrode, the first hole transport layer, the first light-emitting layer, the first electron transport layer, and the charge generation layer, respectively.

[0025] The second insulating layer is connected to the same side of the second light-emitting layer, the second electron transport layer, and the second electrode, respectively.

[0026] Further, the stretchable structure includes a charge generation layer;

[0027] The first insulating layer is connected to the same side of the first electrode, the first hole transport layer, the first light-emitting layer, and the first electron transport layer, respectively.

[0028] The second insulating layer is connected to the same side of the second hole transport layer, the second light-emitting layer, the second electron transport layer, and the second electrode, respectively.

[0029] Further, in the electron transport layer and / or the charge generation layer and / or the hole transport layer in the stretchable structure, a stretchable material is doped.

[0030] Further, the elastic modulus of the stretchable structure is 0.21 MPa - 1.0 MPa.

[0031] Further, in the case where the stretchable structure includes multiple layers, the elastic modulus of each layer in the stretchable structure is of the same order of magnitude.

[0032] Further, the thickness of each layer in the stretchable structure is configured to be more than 1.5 times the thickness of the layer without stretchable performance.

[0033] Further, along the stretchable direction, the total length of the device before stretching is a1, and the total length after stretching is a2. The numerical range of (a2 - a1) / a1 is 0.25 - 0.5.

[0034] In a second aspect, the present invention provides a display panel, including:

[0035] A substrate;

[0036] The display device according to the first aspect, which is arranged in an array on the substrate.

[0037] One or more of the above technical solutions of the present invention have at least one or more of the following beneficial effects:

[0038] In implementing the technical solution of the present invention, a stretchable structure is formed on the flexible display device of the present invention without changing the original layer structure, so that the display panel can still maintain a low graininess in the stretched state and can provide a high-quality image display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Referring to the accompanying drawings, the disclosure of the present invention will become more readily understood. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the protection scope of the present invention. In addition, similar numbers in the drawings are used to represent similar components, wherein:

[0040] Figure 1 is a schematic diagram of the main structure of a flexible display device according to an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of the change of a flexible display device according to an embodiment of the present invention before and after stretching;

[0042] Figure 3 is the size change of a single pixel before and after the directional stretching of a stacked OLED according to an embodiment of the present invention;

[0043] Figure 4 is a schematic diagram before stretching according to Embodiment 1 of the present invention;

[0044] Figure 5 is a schematic diagram after stretching according to Embodiment 1 of the present invention;

[0045] Figure 6 is a schematic diagram before stretching according to Embodiment 2 of the present invention;

[0046] Figure 7 is a schematic diagram after stretching according to Embodiment 2 of the present invention;

[0047] Figure 8 is a schematic diagram before stretching according to Embodiment 3 of the present invention;

[0048] Figure 9 is a schematic diagram after stretching according to Embodiment 3 of the present invention;

[0049] Figure 10 is a schematic diagram before stretching according to Embodiment 4 of the present invention;

[0050] Figure 11 is a schematic diagram after stretching according to Embodiment 4 of the present invention;

[0051] Figure 12 is a schematic diagram of the structure of the comparative example according to the present invention.

[0052] List of Reference Numerals :

[0053] 1: First electrode; 2: First light-emitting unit; 2-1: First hole transport layer, 2-2: First light-emitting layer; 2-3: First electron transport layer; 3: Second light-emitting unit; 3-1: Second hole transport layer; 3-2: Second light-emitting layer; 3-3: Second electron transport layer; 4: Second electrode; 5: Charge generation layer; 6: First insulating layer; 7: Second insulating layer; 8: Substrate; 9: Second pixel layer; 9-1: Second light-emitting part; 9-2: Second stretchable part; 11: Stretchable guiding wire; 10: Inter-pixel interstitial layer; 12: First pixel layer; 12-1: First light-emitting part; 12-2: First stretchable part; 100: First pixel; 200: Second pixel. Detailed implementation manners

[0054] Some implementation manners of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention.

[0055] In the description of the present invention, the term "A and / or B" represents all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one of A or B" or "at least one of A and B" has a meaning similar to "A and / or B" and can include only A, only B, or A and B. The singular terms "one" and "this" can also include the plural form.

[0056] Referring to Figure 1 , the present invention provides a flexible display device, including:

[0057] First electrode 1;

[0058] Second electrode 4; and

[0059] A plurality of light-emitting units stacked in sequence between the first electrode 1 and the second electrode 4, wherein each light-emitting unit includes a hole transport layer, a light-emitting layer, and an electron transport layer stacked in sequence along the direction away from the first electrode 1, and a charge generation layer 5 is provided between adjacent light-emitting units, and one or more of the electron transport layer, the charge generation layer, and the hole transport layer between adjacent light-emitting layers are stretchable structures;

[0060] The orthographic projections of the structures of the display device respectively connected to both sides of the stretchable structure on the substrate at least partially do not overlap.

[0061] In the present invention, by introducing a special stretchable structure, the entire device has significant flexible characteristics. The design of the stretchable structure allows the device to effectively extend and deform when subjected to a stretching force in a specific direction. This ability of directional stretching enables the device to adapt to different usage environments and conditions while maintaining its functions. As Figure 2 shown, it can be seen that after the flexible display device structure is directionally stretched longitudinally, its size changes. The introduction of this stretchable structure provides new possibilities for the flexibility and adaptability of the device.

[0062] The stretchable structure will be specifically described below.

[0063] The arrangement structure of the stretchable structure can be set in any one of the following ways:

[0064] One layer: Any one of the electron transport layer, charge generation layer, and hole transport layer.

[0065] Two layers: Any two adjacent layers among the electron transport layer, charge generation layer, and hole transport layer.

[0066] Three layers: The electron transport layer, charge generation layer, and hole transport layer.

[0067] According to the requirements of actual applications, the number of layers and the type of layers required can be flexibly adjusted and designed to meet different functional and performance requirements.

[0068] To cooperate with the stretchable structure and ensure that it can exhibit good stretching effects when subjected to stretching, in the device of the present invention, the structures of the devices connected to the upper and lower sides of the stretchable structure are specifically designed to adopt a staggered layout method. Specifically, the orthographic projections of the structures of the display devices connected to the two sides of the stretchable structure on the substrate at least partially do not overlap. The advantage of this design is that when a stretching force is applied to the device, the staggered upper and lower structures can more easily enable the device to extend, thereby improving the stretching performance and reliability of the device. Referring to Figure 3 , in the display area of the display panel, the stacked OLED is composed of a plurality of pixel arrays arranged. Taking the example where a single pixel is composed of two light-emitting units (the first light-emitting unit 2 and the second light-emitting unit 3) respectively, the above-mentioned staggered design is illustrated. The two light-emitting units are arranged in a staggered manner. The first light-emitting unit 2 is located in the lower layer, and the second light-emitting unit 3 is located in the upper layer. In Figure 3In this case, the longitudinal direction is used as the direction of the directional stretching for the description. Among them, a1 represents the total length of the device along the stretchable direction before stretching. After the directional stretching process, the total length of the device will increase, and at this time the length becomes a2, where a2 > a1. It should be noted that since this is a directional stretching process, it can be seen that there is no dimensional extension change in the transverse direction. Therefore, before the stretching operation, the transverse dimension is b1. After the stretching operation is completed, the transverse dimension remains unchanged and is still the initial b1 dimension. Through Figure 3 , it can be intuitively seen that after stretching, the original misaligned structure of the two parts becomes more prominent. The appearance of this phenomenon is because the stretchable structure plays its role, enabling the device to be effectively extended in the longitudinal direction.

[0069] In one embodiment, the first electrode 1 is an anode and the second electrode 4 is a cathode. The display device adopts a bottom-emission type stacked OLED. The bottom-emission type stacked OLED combines the dual advantages of a stacked structure and a bottom-emission design. The bottom-emission type can utilize a better optical path design to reduce internal losses, making the brightness superposition effect of the two light-emitting units more efficient.

[0070] In one embodiment, still referring to Figure 1 , the device includes a first light-emitting unit 2 and a second light-emitting unit 3; among them, the first light-emitting unit 2 is closer to the first electrode 1 than the second light-emitting unit 3.

[0071] Along the direction away from the first electrode 1, the first light-emitting unit 1 includes a first hole transport layer 2-1, a first light-emitting layer 2-2, and a first electron transport layer 2-3 stacked in sequence.

[0072] Along the direction away from the first electrode 1, the second light-emitting unit 3 includes a second hole transport layer 3-1, a second light-emitting layer 3-2, and a second electron transport layer 3-3 stacked in sequence.

[0073] The charge generation layer 5 is disposed between the first electron transport layer 2-3 and the second hole transport layer 3-1.

[0074] In one embodiment, referring to Figures 4 - 11 , the device further includes a first insulating layer 6 and a second insulating layer 7, which are used to make the orthographic projections of the structures of the display devices respectively connected to both sides of the stretchable structure on the substrate at least partially non-overlapping; among them, the first insulating layer 6 is connected to the structure of the display device connected to one side of the stretchable structure, and the second insulating layer 7 is connected to the structure of the display device connected to the other side of the stretchable structure.

[0075] In one embodiment, the electron transport layer and / or the charge generation layer and / or the hole transport layer in the stretchable structure are doped with stretchable materials.

[0076] Regarding doping stretchable materials, there are two main technical routes, one is physical doping and the other is chemical doping, as described below:

[0077] 1. Physical doping

[0078] In the existing light-emitting unit production process, stretchable hydrogel or elastomer is doped into the light-emitting material to achieve the stretchability of the light-emitting material.

[0079] 2. Chemical doping (elastic material design)

[0080] For example, the stretching of the light-emitting unit can be achieved by atom transfer radical polymerization (ATRP) of rigid styrene macromolecules and flexible segment butyl acrylate long chains.

[0081] For example, a small amount (5 mol%-20 mol%) of 2,6-pyridinedicarboxamide (PDCA) units is introduced into the main chain of the conjugated polymer to form a cross-linked network based on dynamic hydrogen bonds between the polymer chains. Hydrogen bonds can be easily destroyed during the tensile strain process, and can be spontaneously re-formed during the recovery process, thereby achieving stretching.

[0082] In one embodiment, the elastic modulus of the stretchable structure is 0.21 MPa-1.0 MPa. The elastic model needs to be controlled within a specific range to balance the deformation ability and functional stability and extend the life. If the elastic modulus is not set scientifically, there is a risk of uncontrolled deformation, and even interface delamination or even fracture.

[0083] In one embodiment, when the stretchable structure includes multiple layers, the elastic modulus of each layer in the stretchable structure is of the same order of magnitude. This design enables the entire structure to exhibit a more outstanding cooperative deformation ability when facing dynamic loads such as stretching and bending. Due to the matching of the moduli, fatigue damage caused by uncoordinated deformation can be reduced. In addition, due to the consistency of the modulus, the external force can be evenly transmitted to each layer, which helps to avoid local stress concentration.

[0084] In one embodiment, the thickness of each layer in the stretchable structure is configured to be more than 1.5 times the thickness of the layer without the stretchable property.

[0085] When designing a display device, if a certain layer is selected as a stretching layer, the thickness of the layer is increased by at least 50% to ensure that the film layer will not tear during the stretching process. This design is to improve the flexibility and stretch resistance of the film layer, thereby ensuring the stability and reliability of the display device during use.

[0086] In the conventional solution, the thickness of the first electron transport layer / second hole transport layer is set to 30 - 50 nm, and the thickness of the charge generation layer is 10 - 20 nm.

[0087] In one embodiment, referring to Figure 3 and Figures 4 - 11 , along the stretchable direction, the total length of the device before stretching is a1, and the total length after stretching is a2. The value range of (a2 - a1) / a1 is 0.25 - 0.5. By limiting the stretching length, the stability of the stretchable structure within the controllable deformation range can be ensured, and the balance between deformation uniformity and material strength can be achieved, preventing fracture or delamination, and reducing the fatigue damage rate by restricting the deformation amplitude.

[0088] The present invention also provides a display panel, including:

[0089] A substrate 8;

[0090] The display device arranged in an array formed on the substrate 8.

[0091] The following uses different embodiments to illustrate the structure of applying the flexible display device to the display panel.

[0092] The following embodiments are described with two adjacent pixels.

[0093] In one embodiment, denoted as Embodiment 1, referring to Figures 4 - 5 , the stretchable structure includes a first electron transport layer 2 - 3, a charge generation layer 5, and a second hole transport layer 3 - 1.

[0094] The first insulating layer 6 is connected to the same side of the first electrode 1, the first hole transport layer 2 - 1, and the first light-emitting layer 2 - 2.

[0095] The second insulating layer 7 is connected to the same side of the second light-emitting layer 3 - 2, the second electron transport layer 3 - 3, and the second electrode 4.

[0096] In Embodiment 1, the first electron transport layer 2 - 3, the charge generation layer 5, and the second hole transport layer 3 - 1 are all stretchable materials. The stretchable structure is composed of three layers together to form a stretchable structure. The elastic moduli of the three layers of materials (the first electron transport layer 2 - 3, the charge generation layer 5, and the second hole transport layer 3 - 1) are of the same order of magnitude, avoiding film layer fracture caused by inconsistent stress in different film layers during the stretching process.

[0097] The preparation method of this Embodiment 1 includes:

[0098] S1, forming the first electrode 1 on the substrate.

[0099] S2. On the first electrode 1, a first hole transport layer 2-1 and a first light-emitting layer 2-2 are sequentially formed.

[0100] S3. The first electrode 1, the first hole transport layer 2-1, and the first light-emitting layer 2-2 are patterned to form a first electrode structure, a first hole transport structure, and a first light-emitting structure respectively.

[0101] S4. A first insulating layer 6 is formed on the same side as the first electrode structure, the first hole transport structure, and the first light-emitting structure; the first electrode structure, the first hole transport structure, the first light-emitting structure, and the first insulating layer 6 are located on the same horizontal plane.

[0102] S5. A stretchable structure is sequentially formed on the first light-emitting structure and the first insulating layer 6. Specifically, it includes: a first electron transport layer 2-3, a charge generation layer 5, and a second hole transport layer 3-1 are sequentially formed on the first light-emitting structure and the first insulating layer 6. In step S5, the first electron transport layer 2-3, the charge generation layer 5, and the second hole transport layer 3-1 are all laid over the entire surface.

[0103] S6. A second light-emitting layer 3-2, a second electron transport layer 3-3, and a second electrode 4 are sequentially formed on the second hole transport layer 3-1.

[0104] S7. The second light-emitting layer 3-2, the second electron transport layer 3-3, and the second electrode 4 are patterned to form a second light-emitting structure, a second electron transport structure, and a second electrode structure respectively.

[0105] S8. A second insulating layer 7 is formed on the same side as the second light-emitting structure, the second electron transport structure, and the second electrode structure. The second light-emitting structure, the second electron transport structure, the second electrode structure, and the second insulating layer 7 are located on the same side.

[0106] Although the structures in the drawings of the present invention are the patterned structures, and the layers corresponding to the reference numerals are the names of the layers before patterning, those skilled in the art can still understand the device structure of the present invention.

[0107] For a better stretching effect, the first insulating layer 6 and the second insulating layer 7 are located on both sides of the device, rather than on the same side, so that the upper and lower light emissions can be misaligned.

[0108] In Figures 4 - 5 , the first insulating layer 6 is located on the right side of the first electrode 1, the first hole transport layer 2-1, and the first light-emitting layer 2-2, and the second insulating layer 7 is located on the left side of the second light-emitting layer, the second electron transport layer, and the second electrode.

[0109] In this embodiment, Figures 4 - 5 Taking two adjacent pixels, the first pixel 100 and the second pixel 200 as an example for illustration.Figure 4 It is a schematic diagram before stretching. The two pixel structures are the same, and the size of a single pixel is a1. In the pixel, the first light-emitting layer 2-2 and the second light-emitting layer 3-2 are designed with a dislocation in structure. The first electron transport layer 2-3, the charge generation layer 5, and the second hole transport layer 3-1 are extended and connected to the upper and lower different light-emitting layers. Figure 5 It is a schematic diagram after stretching. Through Figure 4 and 5 By comparison, it can be seen that when directionally stretched, the first electron transport layer 2-3, the charge generation layer 5, and the second hole transport layer 3-1 are deformed by the external force and cause the pixel to stretch. At this time, the size a1 of a single pixel becomes a2, and a single pixel becomes larger through stretching. Multiple pixel arrays are simultaneously directionally stretched to achieve the directional elongation of the display device.

[0110] In one embodiment, denoted as Embodiment 2, referring to Figures 6 - 7 , the stretchable structure includes the first electron transport layer 2-3;

[0111] The first insulating layer 6 is connected to the same side of the first electrode 1, the first hole transport layer 2-1, and the first light-emitting layer 2-2;

[0112] The second insulating layer 7 is connected to the same side of the charge generation layer 5, the second hole transport layer 3-1, the second light-emitting layer 3, the second electron transport layer 3-3, and the second electrode 4.

[0113] The first insulating layer 6 and the second insulating layer 7 are respectively located on both sides of the device.

[0114] As Figure 6 shown, it is a schematic diagram of the film layer structure of two adjacent pixels. Two adjacent pixels include the first pixel 100 and the second pixel 200. The two pixel structures are the same, and the size of a single pixel is a1. In the first pixel 100, the first light-emitting layer 2-2 and the charge generation layer 5 are designed with a dislocation in structure. The film layer of the first electron transport layer 2-3 is extended and connected to the upper and lower different film layers.

[0115] Among them, the first electron transport layer 2-3 uses a stretchable material.

[0116] As Figure 7 shown, when directionally stretched, the first electron transport layer 2-3 is deformed by the external force. At this time, the pixel size of the first pixel 100 becomes a2, and a single pixel becomes larger through stretching. Multiple pixel arrays are simultaneously directionally stretched to achieve the directional elongation of the display panel.

[0117] In one embodiment, denoted as Embodiment 3, referring to Figures 8 - 9 , the stretchable structure includes the second hole transport layer 3-1;

[0118] The first insulating layer 6 is connected to the same side of the first electrode 1, the first hole transport layer 2-1, the first light-emitting layer 2-2, the first electron transport layer 2-3, and the charge generation layer 5 respectively;

[0119] The second insulating layer 7 is connected to the same side of the second light-emitting layer 3, the second electron transport layer 3-3, and the second electrode 4 respectively.

[0120] Figure 8 It is a schematic diagram of the structure of two adjacent pixel film layers. Two adjacent pixels include a first pixel 100 and a second pixel 200. The structures of the two pixels are the same, and the size of a single pixel is a1. In the first pixel 100, the charge generation layer 5 and the second light-emitting layer 3-2 are designed with a dislocation in structure, and the second hole transport layer 3-1 film layer is extended and connected to two different film layers above and below.

[0121] Among them, the second hole transport layer 3-1 is made of a stretchable material.

[0122] As Figure 9 shown, when directionally stretched, the second hole transport layer 3-1 is deformed by the external force. At this time, the pixel size of the first pixel 100 becomes a2, and a single pixel becomes larger through stretching. Multiple pixel arrays are simultaneously directionally stretched to realize the directional elongation of the display device.

[0123] In one embodiment, denoted as Embodiment 4, referring to Figures 10 - 11 , the stretchable structure includes a charge generation layer 5;

[0124] The first insulating layer 6 is connected to the same side of the first electrode 1, the first hole transport layer 2-1, the first light-emitting layer 2-2, and the first electron transport layer 2-3 respectively;

[0125] The second insulating layer 7 is connected to the same side of the second hole transport layer 3-1, the second light-emitting layer 3, the second electron transport layer 3-3, and the second electrode 4 respectively.

[0126] As Figure 10 shown, it is a schematic diagram of the structure of two adjacent pixel film layers. Two adjacent pixels include a first pixel 100 and a second pixel 200. The structures of the two pixels are the same, and the size of a single pixel is a1. In the first pixel 100, the first electron transport layer 2-3 and the second hole transport layer 3-1 are designed with a dislocation in structure, and the charge generation layer 5 film layer is extended and connected to two different film layers above and below.

[0127] Among them, the charge generation layer 5 is made of a stretchable material.

[0128] As Figure 11As shown, after the directional stretching, the charge generation layer 5 is deformed by the external force. At this time, the pixel size of the first pixel 100 becomes a2, and the individual pixel becomes larger through stretching. Multiple pixel arrays are stretched directionally at the same time, thereby realizing the directional elongation of the display panel.

[0129] Combined with the descriptions of Embodiments 1-4, it can be seen that in the present invention, the pixel size is changed through directional stretching, thereby realizing the stretchable display function.

[0130] Comparative Example 1

[0131] Refer to Figure 12 , this comparative example shows a traditional stretchable display device, and a solution for realizing the stretchable display function by setting stretchable wires.

[0132] The structure of the stretchable display panel of Comparative Example 1 includes:

[0133] The stretchable display panel at least includes: a first pixel layer 12 and a second pixel layer 9 arranged in a stacked manner, and a pixel interstitial layer 10 arranged between the first pixel layer 12 and the second pixel layer 9. Among them, a stretchable guiding wire 11 connecting the first pixel layer 12 and the second pixel layer 9 is arranged in the pixel interstitial layer 10. In the comparative example, the first pixel layer 12 and the second pixel layer 9 move in opposite directions under the traction of the stretchable guiding wire 11, so that the light-emitting regions of the first pixel layer 12 and the second pixel layer 9 are at least partially non-overlapping in the stacking direction. In other words, the first pixel layer 12 and the second pixel layer 9 move in the misaligned direction under the traction of the stretchable guiding wire 11.

[0134] Both the first pixel layer 12 and the second pixel layer 9 include a light-emitting part and a stretching part. The light-emitting part corresponds to the light-emitting region of the pixel layer, and the stretching part corresponds to the non-light-emitting region. The first pixel layer 12 includes a plurality of first light-emitting parts 12-1 and first stretchable parts 12-2 arranged around the plurality of first light-emitting parts 12-1. First stress relief holes 12-3 are arranged in the first stretchable parts 12-2 between two adjacent first light-emitting parts 12-1. The second pixel layer 9 includes a plurality of second light-emitting parts 9-1 and second stretchable parts 9-2 arranged around the plurality of second light-emitting parts 9-1. Second stress relief holes 9-3 are arranged in the second stretchable parts 9-2 between two adjacent second light-emitting parts 9-1.

[0135] In the solution of Comparative Example 1, the misalignment amount between the first light-emitting part 12-1 and the second light-emitting part 9-1 is controlled by the expansion and contraction amount of the stretchable guiding wire 11. In this solution, during the stretching of the two pixels, the distance between them is enlarged, and there are problems of increased pixel granularity and image distortion.

[0136] Embodiments 1-4 of the present invention have the following characteristics compared with Comparative Example 1:

[0137] 1. When setting Comparative Example 1, the configuration method of existing wires was adopted. Such a practice led to gaps appearing between adjacent pixels during the stretching process of the device. The existence of these gaps significantly increased the graininess of the device. In the present invention, adjacent pixels are in contact with each other before and after stretching, and there is no problem of significant increase in graininess. Due to the gaps after stretching in Comparative Example 1, there are problems such as image distortion and poor display quality.

[0138] 2. The present invention sets a stretchable structure based on the original layer structure of the device. Therefore, in each embodiment, there is no obvious difference in the optical display effect between the embodiment with the stretchable structure set and the device without the stretchable structure under the same layer structure.

[0139] 3. In Embodiments 1 - 4, stretchable structures with different numbers of layers and compositions were designed and implemented respectively. The stretching amount of each embodiment may vary slightly, which is suitable for different application scenarios.

[0140] 4. In Embodiments 1 - 4 of the present invention, by adjusting the number of layers of the stretchable structure, the types and addition amounts of stretchable materials, etc., precise control of the stretchable amount can be achieved. This flexibility makes the present invention more flexible than the wire limiting method of Comparative Example 1 and can better meet the requirements under various specific application scenarios.

[0141] 5. Compared with the solution of Comparative Example 1, the solutions of Embodiments 1 - 4 of the present invention have a significant increase in the number of cyclic stretching times, thus significantly improving their durability.

[0142] The core of the present invention lies in the ingenious utilization of the original layer structure in the OLED device. Without introducing a new stretchable functional layer structure, by doping stretchable materials in these original layers, the directional stretching function of the device is realized. After the stretching treatment, adjacent pixels can still maintain a tightly fitting state without any gaps. This innovative technology effectively overcomes the problem that in the prior art, when the OLED device is stretched, there is often graininess between pixels, which affects the display effect.

[0143] In summary, through the comparison between Embodiments 1 - 4 and Comparative Example 1, it can be seen that the present invention is based on the stacked OLED design and realizes stretchable display by stretching pixels, which can reduce the graininess of the image after stretching and improve the quality of the displayed image. Specifically, the technical effects of the present invention include:

[0144] 1. Based on the unique light - emitting structure of the stacked OLED, especially the double - layer light - emitting structure, in the directionally stretched state, the upper and lower light - emitting layers of each pixel are misaligned, thereby reducing the graininess of the image after stretching and improving the quality of the displayed image.

[0145] 2. Compared with the intrinsic stretchable display device, the present invention can reduce the number of elastic functional layers, and can set the stretchable structure only relying on the structure of the stacked OLED itself, so as to improve the structural stability and applicability of the device.

[0146] 3. Based on the design of the stacked OLED pixels, the present invention only requires a set of driving circuits to control two sets of light-emitting layers, thereby simplifying the structure of the display device and reducing the circuit cost.

[0147] Thus, the present invention realizes stretchable display in a specific direction and can be applied in the fields of display, lighting, electronic skin, wearable electronic devices, etc.

[0148] It should be noted that although the above steps are described in a specific order in the above embodiments, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order, and they can be executed simultaneously (in parallel) or in other orders, and these changes are all within the protection scope of the present invention.

[0149] So far, the technical solutions of the present invention have been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A flexible display device, characterized in that, Comprising: A first electrode; A second electrode; And A plurality of light-emitting units sequentially stacked between the first electrode and the second electrode, wherein each light-emitting unit includes a hole transport layer, a light-emitting layer, and an electron transport layer sequentially stacked in a direction away from the first electrode, and a charge generation layer is provided between adjacent light-emitting units, and one or more of the electron transport layer, the charge generation layer, and the hole transport layer between adjacent light-emitting layers is a stretchable structure; The orthographic projections of the structures of the display device respectively connected to both sides of the stretchable structure on the substrate at least partially do not overlap.

2. The device according to claim 1, characterized in that, The device includes a first light-emitting unit and a second light-emitting unit; wherein, the first light-emitting unit is closer to the first electrode than the second light-emitting unit; In a direction away from the first electrode, the first light-emitting unit includes a first hole transport layer, a first light-emitting layer, and a first electron transport layer sequentially stacked; In a direction away from the first electrode, the second light-emitting unit includes a second hole transport layer, a second light-emitting layer, and a second electron transport layer sequentially stacked; The charge generation layer is provided between the first electron transport layer and the second hole transport layer.

3. The device according to claim 2, characterized in that, The device further includes a first insulating layer and a second insulating layer for making the orthographic projections of the structures of the display device respectively connected to both sides of the stretchable structure on the substrate at least partially do not overlap; wherein, the first insulating layer is connected to the structure of the display device connected to one side of the stretchable structure, and the second insulating layer is connected to the structure of the display device connected to the other side of the stretchable structure.

4. The device according to claim 3, wherein The stretchable structure includes a first electron transport layer, a charge generation layer, and a second hole transport layer; The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, and the first light-emitting layer; The second insulating layer is respectively connected to the same side of the second light-emitting layer, the second electron transport layer, and the second electrode.

5. The device according to claim 3, characterized in that, The stretchable structure includes a first electron transport layer; The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, and the first light-emitting layer; The second insulating layer is respectively connected to the same side of the charge generation layer, the second hole transport layer, the second light-emitting layer, the second electron transport layer, and the second electrode.

6. The device according to claim 3, wherein The stretchable structure includes a second hole transport layer; The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, the first light-emitting layer, the first electron transport layer, and the charge generation layer; The second insulating layer is respectively connected to the same side of the second light-emitting layer, the second electron transport layer, and the second electrode.

7. The device according to claim 3, characterized in that The stretchable structure includes a charge generation layer; The first insulating layer is respectively connected to the same side of the first electrode, the first hole transport layer, the first light-emitting layer, and the first electron transport layer; The second insulating layer is respectively connected to the same side of the second hole transport layer, the second light-emitting layer, the second electron transport layer, and the second electrode.

8. The device according to claim 1, characterized in that, In the electron transport layer and / or the charge generation layer and / or the hole transport layer of the stretchable structure, a stretchable material is doped.

9. The device according to claim 1, characterized in that, The elastic modulus of the stretchable structure is 0.21 MPa - 1.0 MPa.

10. The device according to claim 1 or 9, characterized in that, In the case where the stretchable structure includes multiple layers, the elastic modulus of each layer in the stretchable structure is of the same order of magnitude.

11. The device according to claim 1, characterized in that, The thickness of each layer in the stretchable structure is configured to be more than 1.5 times the thickness of the layer in the case where it does not have stretchable properties.

12. The device according to claim 1, characterized in that, Along the stretchable direction, the total length of the device before stretching is a1, and the total length after stretching is a2. The numerical range of (a2 - a1) / a1 is 0.25 to 0.

5.

13. A display panel, characterized in that, Comprising: A substrate; An array arrangement of display devices according to any one of claims 1-12 formed on the substrate.

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