Flexible OLED display panel and preparation method thereof

Abstract

The embodiment of the present application provides a flexible OLED display panel and a preparation method thereof. The flexible OLED display panel provided by the embodiment of the present application, by setting a barrier layer between the flexible substrate and the TFT layer, and setting the hydrogen content in the barrier layer to gradually decrease in the direction from the flexible substrate to the TFT layer, so that the hydrogen content of the barrier layer close to the flexible substrate is higher, so that the erosion of water and oxygen from the side of the flexible substrate can be effectively blocked, and the display image degradation and OLED device aging caused by the invasion of external water and oxygen can be avoided. In addition, since the hydrogen content of the barrier layer close to the TFT layer is low or does not contain hydrogen, it can effectively slow down or prevent the diffusion of hydrogen into the TFT layer, eliminate or reduce the influence of hydrogen diffusion in the barrier layer on the electrical properties of the TFT, improve the stability of the image quality of the flexible OLED display panel, and extend the service life of the flexible OLED display panel.

Description

Technical Field

[0001] The present application relates to the field of display, and in particular to a flexible OLED display panel and a preparation method thereof. Background Art

[0002] Organic Light-Emitting Diodes (OLED) are self-luminous devices that have the advantages of being lightweight, low power consumption, fast response, high luminous efficiency, and flexible display. They have become one of the most widely used display devices in recent years. Among them, flexible OLED display panels have become the mainstream product in the current display field.

[0003] The substrate of a flexible OLED display panel is usually a flexible polymer material (such as PI, etc.), which has a significantly lower water and oxygen barrier capability than a glass substrate, resulting in unstable display images of the flexible OLED display panel and accelerating aging of the OLED device. An existing solution is to prepare an inorganic water and oxygen barrier layer, during which H-containing gas is introduced to further increase the density of the barrier layer. However, the problem that follows is that a large amount of H will partially diffuse into the active layer, changing the TFT threshold voltage and causing image quality degradation. Summary of the invention

[0004] The embodiments of the present application provide a flexible OLED display panel and a method for preparing the same. The flexible OLED display panel has stable image quality and a long service life.

[0005] In a first aspect, an embodiment of the present application provides a flexible OLED display panel, comprising:

[0006] Flexible substrates;

[0007] A barrier layer, disposed on one side of the flexible substrate;

[0008] A TFT layer, disposed on a side of the barrier layer away from the flexible substrate;

[0009] An OLED layer, disposed on a side of the TFT layer away from the barrier layer;

[0010] Wherein, in a direction from the flexible substrate to the TFT layer, the content of hydrogen in the barrier layer gradually decreases.

[0011] In some embodiments, the barrier layer includes a plurality of barrier unit layers stacked in sequence from the flexible substrate to the TFT layer, and the content of hydrogen in the plurality of barrier unit layers gradually decreases.

[0012] In some embodiments, the concentration of hydrogen elements in each region within each barrier unit layer is uniform.

[0013] In some embodiments, in a direction from the flexible substrate to the TFT layer, the concentration of hydrogen elements in each of the barrier unit layers gradually decreases.

[0014] In some embodiments, the concentration of hydrogen element in a barrier unit layer disposed closest to the TFT layer among the plurality of barrier unit layers is zero.

[0015] In some embodiments, the thickness of the barrier layer is

[0016] In a second aspect, an embodiment of the present application provides a method for preparing a flexible OLED display panel, comprising:

[0017] Providing a carrier substrate, on which a flexible substrate is disposed;

[0018] A barrier layer is disposed on one side of the flexible substrate, and a TFT layer is disposed on a side of the barrier layer away from the flexible substrate, wherein the content of hydrogen in the barrier layer gradually decreases in a direction from the flexible substrate to the TFT layer;

[0019] Disposing an OLED layer on a side of the TFT layer away from the barrier layer;

[0020] The carrier substrate is removed to obtain a flexible OLED display panel.

[0021] In some embodiments, the material of the barrier layer includes silicon nitride;

[0022] The barrier layer is provided on one side of the flexible substrate, comprising:

[0023] The barrier layer is prepared by a chemical vapor deposition method, and the reaction gas includes silane, ammonia and hydrogen.

[0024] In some embodiments, the proportion of hydrogen in the reaction gas is gradually reduced during the process of preparing the barrier layer.

[0025] In some embodiments, the reaction temperature is gradually increased during the preparation of the barrier layer.

[0026] The flexible OLED display panel provided in the embodiment of the present application is provided with a barrier layer between the flexible substrate and the TFT layer, and the hydrogen content in the barrier layer is gradually reduced in the direction from the flexible substrate to the TFT layer, so that the hydrogen content on the side of the barrier layer close to the flexible substrate is higher, thereby effectively blocking the erosion of water and oxygen from the side of the flexible substrate, avoiding the problems of display image degradation and OLED device aging caused by the invasion of external water and oxygen, and in addition, since the hydrogen content on the side of the barrier layer close to the TFT layer is low or does not contain hydrogen, the diffusion of hydrogen into the TFT layer can be effectively slowed down or prevented, and the influence of the hydrogen diffusion in the barrier layer on the electrical properties of the TFT can be eliminated or reduced, thereby improving the stability of the image quality of the flexible OLED display panel and extending the service life of the flexible OLED display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of the first structure of the flexible OLED display panel provided in an embodiment of the present application.

[0029] Figure 2 A second structural schematic diagram of the flexible OLED display panel provided in an embodiment of the present application.

[0030] Figure 3 This is a schematic diagram of the structure of the barrier layer provided in an embodiment of the present application.

[0031] Figure 4 A flow chart of a method for preparing a flexible OLED display panel provided in an embodiment of the present application.

[0032] Figure 5 A schematic diagram of step S100 of a method for preparing a flexible OLED display panel provided in an embodiment of the present application.

[0033] Figure 6 A schematic diagram of step S200 of a method for preparing a flexible OLED display panel provided in an embodiment of the present application.

[0034] Figure 7 A schematic diagram of step S300 of a method for preparing a flexible OLED display panel provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0036] See also Figure 1 , Figure 1 This is a first structural schematic diagram of a flexible OLED display panel provided in an embodiment of the present application. The embodiment of the present application provides a flexible OLED display panel 100, including a flexible substrate 10, a barrier layer 20, a TFT layer 30 and an OLED layer 40, the barrier layer 20 is arranged on one side of the flexible substrate 10, the TFT layer 30 is arranged on the side of the barrier layer 20 away from the flexible substrate 10, and the OLED layer 40 is arranged on the side of the TFT layer 30 away from the barrier layer 20; wherein, in the direction from the flexible substrate 10 to the TFT layer 30, the content of hydrogen element in the barrier layer 20 gradually decreases.

[0037] It can be understood that the role of the barrier layer 20 is to prevent external water and oxygen from entering the TFT layer 30 and affecting the electrical properties of the TFT device. The flexible OLED display panel 100 provided in the embodiment of the present application is provided with a barrier layer 20 between the flexible substrate 10 and the TFT layer 30, and the content of hydrogen in the barrier layer 20 is gradually reduced in the direction from the flexible substrate 10 to the TFT layer 30, so that the hydrogen content of the barrier layer 20 close to the flexible substrate 10 is relatively high, so that the erosion of water and oxygen from the side of the flexible substrate 10 can be effectively blocked, and the degradation of the display image and the aging of the OLED device caused by the invasion of external water and oxygen can be avoided. In addition, since the hydrogen content of the barrier layer 20 close to the TFT layer 30 is relatively low or does not contain hydrogen, the diffusion of hydrogen into the TFT layer 30 can be effectively slowed down or prevented, and the influence of the diffusion of hydrogen in the barrier layer 20 on the electrical properties of the TFT can be eliminated or reduced, thereby improving the stability of the image quality of the flexible OLED display panel 100 and extending the service life of the flexible OLED display panel 100.

[0038] See also Figure 2 , Figure 2 The flexible OLED display panel 100 may further include an encapsulation layer 50 disposed on a side of the OLED layer 40 away from the TFT layer 30; illustratively, the encapsulation layer 50 may be a thin film encapsulation layer 50 (TFE).

[0039] Please combine Figure 2The flexible OLED display panel 100 may further include a cover plate 60 disposed on a side of the encapsulation layer 50 away from the OLED layer 40 ; illustratively, the cover plate 60 may be a glass substrate.

[0040] See also Figure 3 , Figure 3 Schematic diagram of the structure of the barrier layer provided in an embodiment of the present application. The barrier layer 20 may include a plurality of barrier unit layers 21 stacked in sequence from the flexible substrate 10 to the TFT layer 30, and the content of hydrogen in the plurality of barrier unit layers 21 gradually decreases. It can be understood that by gradually reducing the content of hydrogen in the plurality of barrier unit layers 21, that is, keeping the difference in the content of hydrogen in two adjacent barrier unit layers 21 small, it is beneficial to reduce the film stress between the plurality of barrier unit layers 21 and improve the adhesion between the plurality of barrier unit layers 21.

[0041] In the embodiment of the present application, a plurality refers to two or more than two, for example, three, four, five, six, seven, eight, etc.

[0042] In some embodiments, the concentration of hydrogen elements in each region inside each barrier unit layer 21 is uniform.

[0043] In some other embodiments, the concentration of hydrogen elements in each barrier unit layer 21 gradually decreases in a direction from the flexible substrate 10 to the TFT layer 30 .

[0044] Exemplarily, the concentration of hydrogen in a barrier unit layer 21 disposed closest to the TFT layer 30 among the plurality of barrier unit layers 21 is zero. It can be understood that when the concentration of hydrogen in a barrier unit layer 21 disposed closest to the TFT layer 30 is zero, the diffusion of hydrogen into the TFT layer 30 can be prevented to the greatest extent, thereby improving the electrical stability of the TFT device.

[0045] For example, the thickness of the barrier layer 20 may be For example wait.

[0046] See also Figure 4 , Figure 4 A flowchart of a method for preparing a flexible OLED display panel provided in an embodiment of the present application. An embodiment of the present application provides a method for preparing a flexible OLED display panel, comprising:

[0047] S100, see Figure 5 , providing a carrier substrate 70 , and setting the flexible substrate 10 on the carrier substrate 70 .

[0048] Exemplarily, the carrier substrate 70 may be a rigid substrate, such as a glass substrate.

[0049] For example, before the flexible substrate 10 is disposed on the carrier substrate 70, a sacrificial layer may be disposed on the carrier substrate 70. The material of the sacrificial layer may be a-Si, and the thickness of the sacrificial layer may be When the material of the sacrificial layer is a-Si, the sacrificial layer can be prepared by plasma enhanced chemical vapor deposition (PECVD). It is understandable that by providing the sacrificial layer, after the flexible OLED display panel 100 is subsequently prepared, the sacrificial layer can be irradiated with a laser to weaken the adhesion between the sacrificial layer and the carrier substrate 70, and then the carrier substrate 70 can be peeled off from the sacrificial layer.

[0050] For example, the material of the flexible substrate 10 may be polyimide (PI), and the thickness of the flexible substrate 10 may be

[0051] S200, see Figure 6 A barrier layer 20 is disposed on one side of the flexible substrate 10 , and a TFT layer 30 is disposed on a side of the barrier layer 20 away from the flexible substrate 10 . In a direction from the flexible substrate 10 to the TFT layer 30 , the content of hydrogen elements in the barrier layer 20 gradually decreases.

[0052] For example, the material of the barrier layer 20 may include silicon nitride (SiN x ), in this case, “arranging a barrier layer 20 on one side of the flexible substrate 10” may specifically include: preparing the barrier layer 20 by a chemical vapor deposition method, wherein the reaction gas includes silane (SiH ), ammonia (NH 3 ) and hydrogen (H 2 ).

[0053] In some embodiments, when the barrier layer 20 is prepared by chemical vapor deposition, the proportion of hydrogen in the reaction gas can be gradually reduced during the preparation of the barrier layer 20. It is understood that by gradually reducing the proportion of hydrogen in the reaction gas, the content of hydrogen in the reaction chamber can be gradually reduced, thereby reducing the content of hydrogen in the barrier layer 20.

[0054] Exemplarily, when the barrier layer 20 includes a plurality of barrier unit layers 21 stacked sequentially in a direction from the flexible substrate 10 to the TFT layer 30, the content of hydrogen elements in the plurality of barrier unit layers 21 gradually decreases, and the concentration of hydrogen elements in each region inside each barrier unit layer 21 is uniform, during the deposition of each barrier unit layer 21, the proportion of hydrogen in the reaction gas can be kept constant, thereby allowing the concentration of hydrogen in the reaction chamber to be kept constant.

[0055] Exemplarily, when the barrier layer 20 includes a plurality of barrier unit layers 21 stacked sequentially in a direction from the flexible substrate 10 to the TFT layer 30, the content of hydrogen elements in the plurality of barrier unit layers 21 gradually decreases, and the concentration of hydrogen elements in each barrier unit layer 21 gradually decreases in a direction from the flexible substrate 10 to the TFT layer 30, during the deposition of each barrier unit layer 21, as the reaction time proceeds, the concentration of hydrogen in the reaction chamber may gradually decrease.

[0056] In some other embodiments, when the barrier layer 20 is prepared by chemical vapor deposition, the reaction temperature may be gradually increased during the process of preparing the barrier layer 20. It should be noted that when the reaction temperature is high, SiN x The film is generated quickly, and the SiN generated by the reaction x The residence time in the hydrogen-rich atmosphere is short, so it is not easy to form NH bonds. In addition, when the temperature is high, SiN x The hydrogen element in the film is easy to volatilize, thus reducing the SiN x In addition, it is understood that during the entire preparation process of the barrier layer 20, the reaction temperature needs to be kept below the glass transition temperature of the material (eg, PI) of the flexible substrate 10 to prevent the flexible substrate 10 from deforming or melting.

[0057] Exemplarily, when the barrier layer 20 includes a plurality of barrier unit layers 21 stacked sequentially in a direction from the flexible substrate 10 to the TFT layer 30, the content of hydrogen elements in the plurality of barrier unit layers 21 gradually decreases, and the concentration of hydrogen elements in each region inside each barrier unit layer 21 is uniform, during the deposition of each barrier unit layer 21, the reaction temperature in the reaction chamber can be kept constant.

[0058] Exemplarily, when the barrier layer 20 includes a plurality of barrier unit layers 21 stacked sequentially in a direction from the flexible substrate 10 to the TFT layer 30, the content of hydrogen elements in the plurality of barrier unit layers 21 gradually decreases, and the concentration of hydrogen elements in each barrier unit layer 21 gradually decreases in a direction from the flexible substrate 10 to the TFT layer 30, during the deposition of each barrier unit layer 21, as the reaction time proceeds, the reaction temperature in the reaction chamber may gradually increase.

[0059] For example, “arranging the TFT layer 30 on a side of the barrier layer 20 away from the flexible substrate 10 ” may specifically include:

[0060] S210, using chemical vapor deposition (PVD) method to prepare the light shield, using the mask to define the pattern, the thickness of the light shield is

[0061] S220, a buffer layer (Buffer) is prepared by a chemical vapor deposition (PVD) method. The material of the buffer layer can be silicon oxide (SiO x ) or silicon nitride (SiN x ), the thickness of the buffer layer is

[0062] S230, preparing an active layer by a chemical vapor deposition (PVD) method. The material of the active layer may be an oxide semiconductor, such as indium gallium zinc oxide (IGZO). The thickness of the active layer is Use a mask to define the graphics;

[0063] S240, a gate insulating layer (GI) is prepared by a plasma enhanced chemical vapor deposition (PECVD) method. The material of the gate insulating layer can be silicon oxide (SiOx) or silicon nitride (SiNx). The thickness of the gate insulating layer is

[0064] S250, a gate is prepared by chemical vapor deposition (PVD). The gate material may be a metal, such as molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), etc. The thickness of the gate is Using a yellow light process, the gate pattern is first etched out, and then the gate pattern is self-aligned to etch the gate insulation layer (GI) pattern;

[0065] S260, performing plasma treatment on the entire surface, so that the oxide semiconductor (such as IGZO) without a gate insulating layer and gate protection above is significantly reduced in resistance after being treated, forming an N+ conductor layer, while the oxide semiconductor under the gate insulating layer is not treated, and maintains semiconductor characteristics, serving as a TFT conductive channel layer;

[0066] S270, using a plasma enhanced chemical vapor deposition (PECVD) method to prepare an interlayer dielectric layer (ILD), the material of the interlayer dielectric layer can be silicon oxide (SiOx) or silicon nitride (SiNx), and the thickness of the interlayer dielectric layer is And defining source and drain contact holes of the TFT on the interlayer dielectric layer;

[0067] S280, a source electrode and a drain electrode are prepared by a chemical vapor deposition (PVD) method. The source electrode and the drain electrode may be made of metal, such as molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), etc. The thickness of the source electrode and the drain electrode is Use a mask to define the graphics;

[0068] S290, a passivation layer (PV) is prepared by a plasma enhanced chemical vapor deposition (PECVD) method, and the material of the passivation layer can be silicon oxide (SiOx ) or silicon nitride (SiN x ), the thickness of the passivation layer can be forming a via hole in the passivation layer;

[0069] S291, forming a planar layer (PLN) on the passivation layer, the material of the planar layer may be a positive photoresist material or a negative photoresist material, and the thickness of the planar layer may be 40000 Å; forming a via hole on the planar layer.

[0070] After step S200, the method for preparing a flexible OLED display panel provided in the embodiment of the present application further includes:

[0071] S300, see Figure 7 , an OLED layer 40 is disposed on a side of the TFT layer 30 away from the barrier layer 20 .

[0072] For example, “arranging the OLED layer 40 on a side of the TFT layer 30 away from the barrier layer 20 ” may specifically include:

[0073] S310, preparing an OLED anode (Anode) by a chemical vapor deposition (PVD) method. The material of the OLED anode can be metal, such as molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), indium tin oxide (ITO), etc. The thickness of the OLED anode can be Use a mask to define the graphics;

[0074] S320, preparing a pixel definition layer, and forming an opening on the pixel definition layer to expose the OLED anode;

[0075] S330, forming an OLED light-emitting layer in the opening of the pixel definition layer;

[0076] S340, preparing an OLED cathode on a side of the OLED light-emitting layer away from the OLED anode.

[0077] For example, please combine Figure 2 After step S300 and before removing the carrier substrate 70 , an encapsulation layer 50 may be disposed on a side of the OLED layer 40 away from the TFT layer 30 to encapsulate and protect the OLED device.

[0078] After step S300, the method for preparing a flexible OLED display panel provided in the embodiment of the present application further includes:

[0079] S400, please combine Figure 1 , remove the carrying substrate 70 to obtain the flexible OLED display panel 100.

[0080] Exemplarily, “removing the carrier substrate 70 ” may specifically include: irradiating the sacrificial layer with a laser from a side of the carrier substrate 70 away from the sacrificial layer to weaken the adhesion between the sacrificial layer and the carrier substrate 70 , and then peeling the carrier substrate 70 off the sacrificial layer.

[0081] It should be noted that when the material of the sacrificial layer includes a-Si, due to the a-Si process, the sacrificial layer is usually doped with hydrogen elements. Therefore, when the sacrificial layer is irradiated with laser, the hydrogen elements in the sacrificial layer will escape from the sacrificial layer and be released in the form of hydrogen gas. When the hydrogen content in the sacrificial layer decreases, the adhesion between the sacrificial layer and the supporting substrate 70 is weakened. Therefore, a smaller force can be used to peel the supporting substrate 70 off the sacrificial layer.

[0082] For example, please combine Figure 2 Before or after removing the carrier substrate 70 , a cover plate 60 may be disposed on a side of the encapsulation layer 50 away from the OLED layer 40 .

[0083] The flexible OLED display panel and its preparation method provided by the embodiment of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A flexible OLED display panel, characterized in that: include: Flexible substrates; A barrier layer, disposed on one side of the flexible substrate; A TFT layer, disposed on a side of the barrier layer away from the flexible substrate; An OLED layer, disposed on a side of the TFT layer away from the barrier layer; Wherein, the content of hydrogen in the barrier layer gradually decreases in the direction from the flexible substrate to the TFT layer; The barrier layer comprises a plurality of barrier unit layers stacked in sequence in a direction from the flexible substrate to the TFT layer, and the content of hydrogen in the plurality of barrier unit layers gradually decreases; The concentration of hydrogen elements in each region inside each barrier unit layer is uniform.

2. The flexible OLED display panel according to claim 1, characterized in that: In a direction from the flexible substrate to the TFT layer, the concentration of hydrogen elements in each of the barrier unit layers gradually decreases.

3. The flexible OLED display panel according to claim 1, characterized in that: Among the plurality of barrier unit layers, a concentration of hydrogen element in a barrier unit layer that is disposed closest to the TFT layer is zero.

4. The flexible OLED display panel according to any one of claims 1 to 3, characterized in that: The thickness of the barrier layer is 5. A method for preparing a flexible OLED display panel, characterized in that: include: Providing a carrier substrate, on which a flexible substrate is disposed; A barrier layer is disposed on one side of the flexible substrate, and a TFT layer is disposed on a side of the barrier layer away from the flexible substrate, wherein the content of hydrogen in the barrier layer gradually decreases in a direction from the flexible substrate to the TFT layer; Disposing an OLED layer on a side of the TFT layer away from the barrier layer; Removing the carrier substrate to obtain a flexible OLED display panel; The barrier layer comprises a plurality of barrier unit layers stacked in sequence in a direction from the flexible substrate to the TFT layer, and the content of hydrogen in the plurality of barrier unit layers gradually decreases; The concentration of hydrogen elements in each region inside each barrier unit layer is uniform.

6. The method for preparing a flexible OLED display panel according to claim 5, characterized in that: The material of the barrier layer includes silicon nitride; The barrier layer is provided on one side of the flexible substrate, comprising: The barrier layer is prepared by a chemical vapor deposition method, and the reaction gas includes silane, ammonia and hydrogen.

7. The method for preparing a flexible OLED display panel according to claim 6, characterized in that: In the process of preparing the barrier layer, the proportion of hydrogen in the reaction gas is gradually reduced.

8. The method for preparing a flexible OLED display panel according to claim 6, characterized in that: The reaction temperature is gradually increased during the preparation of the barrier layer.

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