CN108807496B - Organic electroluminescent display panel and display device - Google Patents
Organic electroluminescent display panel and display device Download PDFInfo
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- CN108807496B CN108807496B CN201810871655.4A CN201810871655A CN108807496B CN 108807496 B CN108807496 B CN 108807496B CN 201810871655 A CN201810871655 A CN 201810871655A CN 108807496 B CN108807496 B CN 108807496B
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/123—Connection of the pixel electrodes to the thin film transistors [TFT]
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Abstract
The invention relates to an organic electroluminescent display panel, comprising a passivation layer and a pixel electrode; the pixel electrode is formed on the passivation layer; portions of at least one of the pixel electrodes are embedded within the passivation layer. Therefore, by embedding part of the pixel electrode into the passivation layer, on one hand, stress can be effectively dispersed when the display panel is impacted or bent; on the other hand, the contact area between the pixel electrode and the passivation layer is increased, so that the pixel electrode and the passivation layer have better bonding force, and compared with the conventional design that the film layers are adhered by Van der Waals force, the adhesion of the electrode is improved. Therefore, the pixel electrode is effectively prevented from being broken or partially stripped, and the bending resistance and the falling impact strength bearing reliability of the OLED display panel are effectively improved. A display device is also provided.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to an organic electroluminescent display panel and a display device.
Background
In recent years, with the development of society and the advancement of science and technology, the technical development of intelligent terminal devices and wearable devices is changing day by day, the requirements for flat panel display are gradually increased, and the requirements are more and more diversified. Since an OLED (Organic Light-Emitting Diode) display device has the advantages of lower power consumption, higher brightness and response speed, better flexibility and better flexibility compared with a liquid crystal display, the OLED display device is more and more widely applied to smart terminal products such as mobile phones, tablet computers, and even televisions, and becomes a mainstream display in the display field.
In order to pursue better visual experience and touch experience, the requirements on the effective display area and thickness of the OLED organic electroluminescent display panel are higher and higher, but the strength of the organic electroluminescent display panel is reduced along with the increase of the effective display area and the reduction of the thickness of the OLED organic electroluminescent display panel, and particularly, when the flexible OLED organic electroluminescent display panel is bent or curled for many times and bears falling impact, the bent area and the hit area cannot display in full color, and poor display such as black spots, bright spots, color spots and the like is prone to occur.
Therefore, how to improve the intensity reliability of the OLED organic electroluminescent display panel is a problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of the above, it is necessary to provide an organic electroluminescent display panel and a display device that improve the above problem, in view of the problem that the organic electroluminescent display panel is prone to display defects when bent and subjected to a drop impact.
An organic electroluminescent display panel comprising:
a thin film transistor disposed on the substrate;
a passivation layer formed on the thin film transistor and configured to have a contact hole exposing a drain electrode of the thin film transistor;
the pixel electrode is formed on the passivation layer and is connected to the drain electrode of the thin film transistor through the contact hole;
wherein a portion of at least one of the pixel electrodes is embedded within the passivation layer.
Optionally, the organic electroluminescent display panel further comprises a first recess formed on the passivation layer;
portions of the pixel electrode are located within the first recess.
Optionally, the depth of the first recess is greater than the film thickness of the pixel electrode located in the first recess.
Optionally, the organic electroluminescent display panel further comprises a pixel defining layer;
the pixel defining layer is formed on the passivation layer and defines a pixel defining opening for exposing at least a portion of the pixel electrode;
the pixel electrode has an active area exposed by the pixel defining opening; the part of the pixel electrode embedded in the passivation layer is at least positioned in the effective area of the pixel electrode.
Optionally, the organic electroluminescent display panel further comprises a pixel defining layer;
the pixel defining layer is formed on the passivation layer and defines a pixel defining opening for exposing at least a portion of the pixel electrode;
portions of the pixel definition layer are embedded within the passivation layer.
Optionally, the organic electroluminescent display panel further comprises a groove formed on the passivation layer; the pixel definition layer covers in the groove;
each of the grooves is disposed around at least a portion of one of the pixel electrodes.
Optionally, the organic electroluminescent display panel further comprises a pixel definition layer, and a cathode covering the pixel definition layer;
a portion of the cathode is embedded within the pixel defining layer.
Optionally, the organic electroluminescent display panel further comprises a second recess formed on a surface of the pixel defining layer facing away from the passivation layer;
a portion of the cathode is located within the second recess.
Optionally, the organic electroluminescent display panel further comprises a first recess formed on the passivation layer;
a portion of the pixel electrode is located within the first recess;
the second concave part faces the orthographic projection of the passivation layer and is spaced from the first concave part.
A display device includes the organic electroluminescent display panel as in the above embodiments.
According to the organic electroluminescence display panel and the display device, the part of the pixel electrode is embedded into the passivation layer, so that on one hand, stress can be effectively dispersed when the display panel is impacted or bent; on the other hand, the contact area between the pixel electrode and the passivation layer is increased, so that the pixel electrode and the passivation layer have better bonding force, and compared with the conventional design that the film layers are adhered by Van der Waals force, the adhesion of the electrode is improved. Therefore, the pixel electrode is effectively prevented from being broken or partially stripped, and the bending resistance and the falling impact strength bearing reliability of the OLED display panel are effectively improved.
Drawings
FIG. 1 is a schematic cross-sectional view of a sub-pixel region of an organic electroluminescent display panel without a cathode formed thereon according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of a sub-pixel region when the organic electroluminescent display panel shown in fig. 1 is formed with a cathode;
fig. 3 is a flowchart illustrating a method for fabricating an organic electroluminescent display panel according to an embodiment of the invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In describing positional relationships, when an element such as a layer, film or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present, unless otherwise specified. Further, when a layer is referred to as being "under" another layer, it can be directly under, or one or more intervening layers may also be present. It will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
Where the terms "comprising," "having," and "including" are used herein, another element may be added unless an explicit limitation is used, such as "only," "consisting of … …," etc. Unless mentioned to the contrary, terms in the singular may include the plural and are not to be construed as being one in number.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention.
It will also be understood that when interpreting elements, although not explicitly described, the elements are to be interpreted as including a range of errors which are within the acceptable range of deviation of the particular values as determined by those skilled in the art. For example, "about," "approximately," or "substantially" may mean within one or more standard deviations, without limitation.
Further, in the specification, the phrase "plane distribution diagram" refers to a drawing when the target portion is viewed from above, and the phrase "sectional diagram" refers to a drawing when a section taken by vertically cutting the target portion is viewed from the side.
Furthermore, the drawings are not 1: 1, and the relative dimensions of the various elements in the figures are drawn for illustration only and not necessarily to true scale.
With the rapid development of OLED display panel technology, OLED display panels have the characteristics of flexibility and good flexibility, and are widely used. In order to achieve flexibility of the OLED display panel, firstly, a flexible substrate is required, and secondly, compared with a widely adopted glass cover plate packaging method, a Thin Film Encapsulation (TFE) is more suitable for the flexible OLED display panel.
Generally, in such a package structure, a thin film encapsulation layer covers the cathode smoothly and contacts the Array layer (Array) of the display panel in a frame area outside the display area (AA). However, the reliability of the OLED display panel in bending resistance and drop impact strength is not high due to the structure and materials.
Taking a drop impact test as an example, when a 32.65g drop ball (a steel ball with a diameter of 20 mm; a drop height of 2cm-62.5cm) is hit on the OLED display panel, the thin film encapsulation layer will bend downward along the direction of the applied force, and then the stress is transferred to the structure in the thin film encapsulation layer. Because the stress concentration at the moment of being hit by the falling ball cannot be dispersed, when the falling height exceeds 10cm, the display panel is extremely easy to be damaged, the hit area is likely to fail to display in full color, and the bad phenomena such as black spots, bright spots, color spots and the like occur.
In order to solve the problem in the existing design, one way is to make a buffer layer on the light emitting side far away from the screen body, for example, an optical transparent adhesive is filled between the display panel and the cover plate, but the thickness of the screen body is increased to a certain extent, the visual experience and the touch experience of a better quality cannot be met, and the process flow and the making difficulty are increased.
Therefore, it is necessary to provide a display panel with better bending strength and impact strength in case of falling while ensuring the thickness and display effect.
The OLED display panel generally includes an array substrate, an anode (pixel electrode) disposed on the array substrate, an OLED light emitting device, and a cathode. The light emitting principle of the OLED is that semiconductor materials and organic light emitting materials emit light by carrier injection and recombination under the driving of an electric field. Under the drive of a certain voltage, electrons and holes are injected from a cathode and an anode respectively and migrate to an OLED light-emitting device, and are recombined in the OLED light-emitting device to form excitons and excite light-emitting molecules, and the excitons relax through radiation to emit visible light.
In the existing design, each sub-pixel is controlled to emit light or not by a TFT array circuit, each sub-pixel corresponds to an anode, and the cathode covers the entire surface of the pixel defining layer to provide electrons for the OLED light emitting device. It has been found that the anode and cathode are typically formed by vacuum deposition, and that many of the layers are attached to each other by van der waals forces, which are very weak but relatively strong. When the panel is impacted or bent many times, the film packaging layer is bent downwards along the direction of the acting force, and the impact force is transmitted to the films of the cathode, the pixel defining layer, the anode, the passivation layer and the like, so that the internal stress of the display panel is uneven, the phenomenon that the anode and the cathode are partially peeled off is caused, and even the tearing is caused, and the poor display is caused. Therefore, the application range and the bending mode of the flexible OLED display panel are greatly limited.
According to the invention, part of the pixel electrode is embedded into the passivation layer, and part of the cathode is embedded into the pixel defining layer, so that on one hand, when the display panel is impacted or bent, the stress can be effectively dispersed; on the other hand, the contact area between the cathode and the pixel defining layer and the contact area between the pixel electrode and the passivation layer are increased, so that the cathode and the pixel defining layer and the pixel electrode and the passivation layer have better bonding force, and compared with the existing design that the film layers are adhered by Van der Waals force, the adhesion of the electrodes is improved.
Therefore, the breakage or local peeling of the cathode and the pixel electrode is effectively avoided, and the bending resistance and the falling impact strength bearing reliability of the OLED display panel are effectively improved.
It can be understood that the display panel provided in the embodiment of the present invention is mainly applied to a full-screen or frameless display panel, and may also be applied to a general display panel with a frame or a narrow frame.
Before describing the organic electroluminescent display panel in the present invention, some terms are explained first:
an array substrate: that is, a Thin-film transistor (TFT) array substrate refers to a substrate (for example, a substrate made of PI material) on which at least a TFT array is formed.
Passivation layer: the passivation layer is formed on the thin film transistor, for example, in some embodiments, may be formed of a single inorganic layer or a plurality of inorganic layers formed such as silicon oxynitride or silicon nitride; in other embodiments, the passivation layer may be a single layer or a plurality of layers formed of organic and/or inorganic materials. In particular, the passivation layer may serve to protect the thin film transistor on the one hand and may not be flat on the top surface thereof on the other hand since the thin film transistor has a complicated layer structure, and may also form a sufficiently flat top surface. After the passivation layer is formed, a contact hole may be formed in the passivation layer to expose a source electrode or a drain electrode of the thin film transistor.
Fig. 1 is a schematic cross-sectional view illustrating a sub-pixel region of an organic electroluminescent display panel without a cathode formed therein according to an embodiment of the present invention; for the purpose of illustration, the drawings show only the structures associated with embodiments of the invention.
Referring to the drawings, the organic electroluminescent display panel includes an array substrate 12, a passivation layer 14, a pixel electrode 16, an organic light emitting unit 19, a cathode 11, and an encapsulation layer (not shown).
The array substrate 12 includes a substrate 122 (e.g., formed of PI material), and a thin film transistor (not shown) disposed on the substrate 122. Of course, the array substrate 12 may further include a film layer such as an interlayer insulating layer and a buffer layer, which is not limited herein. The passivation layer 14 is formed on the thin film transistor and is configured to have a contact hole exposing a drain electrode of the thin film transistor. This way, it is possible to protect the thin film transistor on the one hand and to form a sufficiently flat top surface on the other hand.
A pixel electrode 16, i.e., an anode electrode, formed on the passivation layer 14 and connected to the drain electrode of the thin film transistor through the contact hole; for convenience of description, the pixel electrode 16 will be described as an example. The array substrate 12 has a plurality of sub-pixel regions, for example, in some embodiments, the array substrate 12 has a first sub-pixel region emitting red light, a second sub-pixel region emitting blue light, and a third sub-pixel region emitting green light, and a set of the first sub-pixel region, the second sub-pixel region, and the third sub-pixel region may constitute one pixel region.
It is understood that in other embodiments, each pixel region may also include other sub-pixel regions, which are not limited herein, for example, a fourth sub-pixel region emitting white light may also be included.
In some embodiments, the pixel electrode 16 may be a transparent electrode, a translucent electrode, or a reflective electrode. For example, when the pixel electrode 16 is a transparent electrode, the pixel electrode 16 may include Indium Tin Oxide (ITO), indium zinc oxide, indium potassium oxide, aluminum zinc oxide, or the like. When the pixel electrode 16 is a reflective electrode, it may include silver, magnesium, aluminum, platinum, gold, nickel, etc.
In some embodiments, the organic electroluminescent display panel further includes a pixel defining layer 18, and the pixel defining layer 18 is formed on the passivation layer 14 and exposes at least a portion of each pixel electrode 16. For example, the pixel defining layer 18 may cover at least a portion of an edge of each pixel electrode 16, thereby exposing at least a portion of each pixel electrode 16. Thus, the pixel defining layer 18 defines a plurality of pixel defining openings and a spacing region (not shown) between the pixel defining openings, and a middle portion or a whole portion of the pixel electrode 16 is exposed through the pixel defining openings.
In this way, the pixel defining layer 18 can increase the distance between the end portion of each pixel electrode 16 and the opposite electrode (cathode 11) formed on each pixel electrode 16, and can prevent antireflection from occurring at the end portion of the pixel electrode 16.
It is understood that in other embodiments, the passivation layer 14 may also be used to define a light emitting region, and is not limited thereto. Specifically, the passivation layer 14 may be configured to cover an edge portion of the pixel electrode to define a pixel defining opening to define a light emitting region; at this time, the pixel defining layer 18 does not need to be provided to define the light emitting region.
The organic light emitting unit 19 is filled in the pixel defining opening. Generally, the organic light emitting unit 19 includes at least a light emitting layer, for example, in some embodiments, the organic light emitting unit 19 may further include a film layer such as a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, and an electron injection layer, which are not limited herein. The organic light emitting unit 19 may be formed, for example, using various methods such as a vacuum deposition method, a spin coating method, a casting method, a langmuir-blodgett (LB) method, an inkjet printing method, a Laser Induced Thermal Imaging (LITI) method, and the like, without being limited thereto.
In some embodiments, the cathode 11 may cover the entire surface of the pixel defining layer 18, and in other embodiments, the cathode 11 may cover the entire surface of the passivation layer 14. Of course, in other embodiments, the cathode 11 may also be patterned on the pixel defining layer 18 or the passivation layer 14, which is not limited herein. The cathode 11 can be made of metals with lower power function, such as silver, lithium, magnesium, calcium, strontium, aluminum, indium, etc., or metal compounds or alloy materials. For example, the organic light emitting unit 19 in the pixel defining openings may be covered by a method of evaporation, and the spaced regions between the pixel defining openings may be formed.
The encapsulation layer is disposed on a side of the organic light emitting unit 19 facing away from the array substrate 12. It is easily understood that since the organic light emitting material layer is sensitive to external environments such as moisture and oxygen, if the organic light emitting material layer in the display panel is exposed to moisture or oxygen, the performance of the display panel may be drastically reduced or completely damaged. The encapsulation layer can block air and moisture for the organic light emitting unit 19, thereby ensuring reliability of the display panel.
It is understood that the encapsulation layer may be one or more layers, and may be an organic layer or an inorganic layer, or a stacked layer of an organic layer and an inorganic layer. For example, in some embodiments, the encapsulation layer may include two inorganic film layers and an organic film layer disposed between the two inorganic film layers.
In an embodiment of the present invention, portions of at least one pixel electrode 16 are embedded within the passivation layer 14. In some embodiments, the passivation layer 14 has a first recess 142 formed thereon; portions of the pixel electrode 16 are located in the first recess 142, thereby forming an embedded structure in which portions of the pixel electrode 16 are embedded in the passivation layer 14. Specifically, the first recess 142 may include at least one of a hole, a groove, or a crack, for example, in some embodiments, a plurality of embedding holes may be formed through a patterning process on the passivation layer 14, and then sputtering film formation of the pixel electrode 16 may be performed, so that the pixel electrode 16 may be partially embedded in the passivation layer 14. In other embodiments, multiple grooves with the same or different depths, intersecting or not intersecting, may be formed, and the pixel electrode 16 may be partially embedded in the passivation layer 14.
Thus, a contact area between the pixel electrode 16 and the passivation layer 14 is increased, thereby increasing a bonding force therebetween. When the display panel bears falling impact, the impact force is transmitted to the OLED layer, the problem that the film layer is peeled off due to the action of external force can be reduced, and the bending strength and the falling impact strength of the display panel are improved.
It is understood that when the display panel is subjected to an impact, the impact is transmitted to the film layer mechanism in the encapsulation layer. The pixel electrode 16 is partially embedded in the passivation layer 14, which can also release stress, further reduce the risk of peeling or breaking of the film layer due to external force, and improve the stress resistance of the pixel electrode 16 itself.
It is also understood that the pixel electrodes 16 and the organic light emitting units 19 are provided in a plurality and correspond to each other, and in the present technical concept, at least one pixel electrode 16 may have the above-described embedded structure. Of course, in some embodiments, all of the pixel electrodes 16 may have the embedded structure, i.e., each pixel electrode 16 is partially embedded in the passivation layer 14.
It should be noted that the first recess 142 may completely penetrate the passivation layer 14, or may not completely penetrate the passivation layer 14, and is not limited herein. For example, in some embodiments, the first recess 142 is a hole, which may or may not completely penetrate the passivation layer 142; in other embodiments, the first recess 142 includes a plurality of grooves, and in order to ensure the strength of the passivation layer, the first recess 142 may not completely penetrate the passivation layer 142. It should be noted that when the first recess 142 penetrates the passivation layer 14, it is ensured that no electrical conduction between the pixel electrode 16 and the tft occurs, which is a problem.
In some embodiments, the depth of the first recess 142 is greater than the film thickness of the pixel electrode 16 located in the first recess 142. For example, the first recess 142 is a groove, and when the pixel electrode 16 is sputtered to form a film, the pixel electrode 16 does not fill the groove, so that a recess is also formed on a side of the pixel electrode 16 away from the passivation layer 14. In this way, when the pixel defining layer 18 and the organic light emitting unit 19 are formed subsequently, the embedded structure embedded in the pixel electrode 16 is also formed.
In this way, the bonding force between the pixel electrode 16 and the pixel defining layer 18 and the organic light emitting unit 19 is also increased, and when the display panel is subjected to a drop impact, the impact force is transmitted to the OLED layer, so that the problem of peeling of the film layer due to an external force can be reduced, and thus the bending strength and the drop impact strength of the display panel are improved.
In some embodiments of the present invention, the pixel electrode 16 has an active area exposed by the pixel defining opening; the portion of the pixel electrode 16 embedded in the passivation layer 14 is at least in the active area.
It is to be understood that the pixel defining layer 18 defines a plurality of pixel defining openings to expose partial areas of the pixel electrodes 16. The organic light emitting unit 19 is disposed in the pixel defining opening and contacts with the exposed partial area of the pixel electrode 16, so that the area of the pixel electrode 16 contacting with the organic light emitting unit 19 is the effective area of the pixel electrode 16. The area of the pixel electrode 16 covered by the pixel defining layer 18 is not in contact with the organic light emitting unit 19, and this area is referred to as an inactive area of the pixel electrode 16.
The inventor of the application finds that in a ball drop reliability test of a soft screen, a steel ball hits the screen, the hit area cannot be displayed in full color instantly, and poor display such as black spots, bright spots and color spots appear in the display area. The damage of the element is mainly caused by the fact that stress concentration cannot be dispersed at the moment of hitting a heavy object, and the important reason is that peeling easily occurs between films with poor adhesion when dropping balls concentrate on the panel, and particularly, peeling easily occurs between the organic light emitting unit 19 and the pixel electrode 16, thereby causing the display failure of the product.
Therefore, the portion of the pixel electrode 16 embedded in the passivation layer 14 is at least located in the effective area of the pixel electrode 16, which can better protect the contact area between the organic light emitting unit 19 and the pixel electrode 16, and reduce the problem of film peeling caused by external force.
In some embodiments of the present invention, a portion of the pixel defining layer 18 is embedded in the passivation layer 14, for example, in some embodiments, a groove 144 is formed on the passivation layer 14, and the pixel defining layer 18 covers the groove 144. In this way, the bonding strength between the pixel defining layer 18 and the passivation layer 14 can be enhanced, the problem of film peeling caused by external force can be further reduced, and the bending strength and the drop impact strength of the display panel can be improved.
Note that the pixel defining layer 18 is typically formed of an organic material, for example, an organic material such as polyimide, polyamide, benzocyclobutene, acryl resin, or phenol resin. In some embodiments, the passivation layer 14 may be formed of a single inorganic layer or multiple inorganic layers such as a layer of silicon oxynitride or silicon nitride; in other embodiments, the passivation layer 14 may be a single layer or multiple layers formed of organic and/or inorganic materials. It is easily understood that the bonding force between inorganic materials is generally stronger than that between organic materials and that between inorganic and organic materials. Therefore, in some embodiments, the pixel defining layer 18 may also be doped with an inorganic material, such as tin oxide, silicon nitride and/or tin oxynitride. In the actual manufacturing process, the bonding force between the passivation layer 14 and the surface of the passivation layer facing away from the array substrate 12 can be increased.
It should be further noted that the groove 144 may or may not completely penetrate the passivation layer 14, and is not limited herein.
In some embodiments, each groove 144 is disposed around at least a portion of one pixel electrode 16. The inventors have found that a recess 144 is formed in the passivation layer 14 around the pixel electrode 16 and the pixel defining layer 18 is partially embedded in the recess 144. When the display panel is subjected to a drop impact, the impact force is transmitted to the pixel defining layer 18 and the passivation layer 14, and the pixel defining layer 18 and the passivation layer 14 expand toward the extension direction thereof. The groove 144 is disposed around the pixel electrode 16, and similar to a fence structure, and can release stress, so as to reduce expansion of the pixel defining layer 18 and the passivation layer 14, thereby effectively avoiding stress from pressing the pixel electrode 16 and the organic light emitting unit 19 to cause failure thereof. In addition, when the display panel is a flexible display panel, the flexibility of the flexible display panel can be improved better.
It is understood that in some embodiments, one or more of the aforementioned grooves 144 may be disposed around each pixel electrode 16; in other embodiments, one or more of the above-mentioned grooves 144 may be disposed only around a portion of the pixel electrode 16, which is not limited herein. Wherein a plurality means two or more.
It is understood that the number of the grooves 144 around each pixel electrode 16 may be the same or different, and is not limited herein. Taking the drop impact resistance as an example, in a drop impact test, if a ball is likely to hit the middle of the effective display area of the display panel, the number of the grooves 144 around the pixel electrode 16 located at the middle of the effective display area is larger, and the number of the grooves 144 around the pixel electrode 16 located at the frame area in the effective display area can be reduced appropriately. Taking the multi-bending as an example, the number of the grooves 144 around the pixel electrode 16 in the bending region is larger, and the number of the grooves 144 around the pixel electrode 16 in the non-bending region can be reduced appropriately.
It is further understood that each of the grooves 144 is disposed around one of the pixel electrodes 16, and the groove 144 may be a continuously formed groove 144, or may include a plurality of sub-grooves 144 intermittently disposed along the circumference of the pixel electrode 16, so as to achieve the purpose of reducing the expansion of the pixel defining layer 18 and the passivation layer 14 caused by the impact, which is not limited herein.
Fig. 2 is a schematic cross-sectional view showing a sub-pixel region when an organic electroluminescent display panel is formed with a cathode 11 according to an embodiment of the present invention; for the purpose of illustration, the drawings show only the structures associated with embodiments of the invention.
Referring to fig. 2, in some embodiments of the present invention, portions of the cathode 11 are embedded within the pixel defining layer 18. For example, a side surface of the pixel defining layer 18 facing away from the passivation layer 14 is formed with a second recess 182; portions of the cathode 11 are located within the second recess 182, thereby forming an embedded structure in which portions of the cathode 11 are embedded within the pixel defining layer 18. Specifically, second recess 182 may include at least one of a hole, a groove, or a crack, for example, in some embodiments, a plurality of embedding holes may be formed by a patterning process on pixel defining layer 18, and then a cathode 11 layer may be formed, such that cathode 11 may be partially embedded within pixel defining layer 18. In other embodiments, multiple grooves with the same or different depths, intersecting or not intersecting, may be formed, and the cathode 11 may be partially embedded in the pixel defining layer 18.
The inventor of the present application has found that in the prior art, each sub-pixel is controlled to emit light or not by the TFT array circuit, each sub-pixel corresponds to one pixel electrode 16, and the cathode 11 covers the entire surface of the pixel defining layer 18 and the organic light emitting unit 19 to provide electrons for the OLED light emitting device. It is found that, during the panel being impacted or bent many times, the encapsulation layer will bend downwards along the direction of the applied force, the probability of the cathode 11 being hit is almost 100%, which easily causes the film layer of the cathode 11 to break or peel off from the organic light emitting unit 19 and the pixel electrode 16 layer, resulting in poor display.
By arranging the second recess 182 on the pixel defining layer 18, the cathode 11 layer is partially embedded, so that the bonding force between the cathode 11 and the pixel defining layer 18 is enhanced, and the bonding force between the organic light emitting unit 19 and the cathode 11 is indirectly enhanced, thereby improving the problem of poor display caused by peeling between the organic light emitting unit 19 and the cathode 11 when an external force is applied, and improving the bending strength and the drop impact strength of the display panel.
In some embodiments, the second recess 182 is spaced apart from the first recess 142 toward an orthographic projection of the passivation layer 14. For example, in some embodiments, the first recess 142 includes a plurality of first grooves extending lengthwise; the second recess 182 includes a plurality of second grooves extending lengthwise, and the first grooves and the second grooves are parallel to each other. The orthographic projection of the second recesses towards the passivation layer 14 is located in the spacing region between the first recesses.
It should be understood that, for example, in a drop impact test, when the OLED display panel is hit by using a 32.65g drop ball (a steel ball with a diameter of 20 mm; a drop height of 2cm-62.5cm), the encapsulation layer will bend downward along the direction of the applied force, and further transmit the stress to the film layer in the thin film encapsulation layer, and if the orthographic projections of the first groove and the second groove on the passivation layer 14 coincide or partially coincide with each other, the stress may be rapidly transmitted downward along the corresponding region of the groove, and a good stress releasing effect cannot be achieved. Therefore, when the orthogonal projection of the second recess 182 toward the passivation layer 14 is spaced apart from the first recess 142, a better stress releasing effect can be achieved, thereby further reducing the problem of film peeling caused by external force, and improving the bending strength and the drop impact strength of the display panel.
In order to further understand the technical solution of the present invention, an embodiment of the present invention further provides a method for manufacturing an organic electroluminescent display panel.
Fig. 3 is a block flow diagram illustrating a method of fabricating an organic electroluminescent display panel in an embodiment of the invention;
referring to the drawings, a method for fabricating an organic electroluminescent display panel according to an embodiment of the present invention includes:
step S120: forming a passivation layer 14;
the passivation layer 14 is formed on the array substrate 12, and particularly, the passivation layer 14 is formed on the thin film transistor. For example, in some embodiments, the inorganic layer may be formed of a single inorganic layer or a plurality of inorganic layers such as a layer of silicon oxynitride or silicon nitride; in other embodiments, the passivation layer 14 may be a single layer or multiple layers formed of organic and/or inorganic materials.
Step S130: forming a pixel electrode 16 on the passivation layer 14; wherein portions of the pixel electrode 16 are embedded within the passivation layer 14;
for example, the pixel electrode 16 may be formed by forming an embedding hole on the passivation layer 14 by patterning, and then sputtering film-forming such that the pixel electrode 16 is partially positioned in the embedding hole. The access holes may be formed by patterning the passivation layer 14 using a patterning process, for example, in some embodiments, the passivation layer 14 may be exposed through a mask and then developed to form the aforementioned access holes, and in other embodiments, the access holes may be formed using an etching process. It is understood that the patterning process may also take other forms, including but not limited to the two forms exemplified above.
In some embodiments, step S130 is followed by:
step S140: forming a pixel defining layer 18 and a cathode electrode 11 on the passivation layer 14; portions of the cathode 11 are embedded within the pixel defining layer 18.
In some embodiments, the pixel defining layer 18 covers at least a portion of an edge of each pixel electrode 16, defining a pixel defining opening that exposes a portion of each pixel electrode 16. The pixel defining layer 18 may be an organic material layer, for example, formed of an organic material such as polyimide, polyamide, benzocyclobutene, acryl resin, or phenol resin. A plurality of pixel defining openings may be formed on the passivation layer 14 by a coating or inkjet printing process and patterned.
Meanwhile, the second recess 182 may be formed by patterning the pixel defining layer 18 using a patterning process, for example, in some embodiments, the pixel defining layer 18 may be exposed through a mask and then developed, so as to form the second recess 182, and in other embodiments, the second recess 182 may be formed using an etching process. It is understood that the patterning process may also take other forms, including but not limited to the two forms exemplified above.
The cathode 11 can cover the entire surface of the pixel defining layer 18, and the cathode 11 material is also formed in the second recess 182, so that the cathode 11 is partially embedded in the pixel defining layer 18.
It is understood that, in some embodiments, a groove 144 may also be formed on the passivation layer 14 between step S130 and step S140 to embed a portion of the pixel defining layer 18 within the passivation layer 14.
In some embodiments, the method further comprises:
step S110: providing an array substrate 12;
the array substrate 12 includes a substrate 122 and a thin film transistor.
For example, the substrate 122 is formed on a carrier substrate. The substrate base plate 122 is a bendable base plate, and is optionally formed of an organic polymer, silicon nitride, and silicon oxide, for example, the organic polymer may be one of a polyimide base plate, a polyamide base plate, a polycarbonate base plate, a polyphenylene ether sulfone base plate, and the like. In some embodiments, the substrate 122 may be obtained by coating a polyimide glue solution on the carrier substrate, and then curing the polyimide.
The thin film transistor is formed on the base substrate 122, and in some embodiments, an additional layer such as a buffer layer may be formed on the base substrate 122 before forming the thin film transistor. The buffer layer may be formed on the entire surface of the base substrate 122, or may be formed by patterning.
The buffer layer may have a suitable material including PET, PEN polyacrylate and/or polyimide, etc., forming a layered structure in a single layer or a multi-layer stack. The buffer layer may also be formed of silicon oxide or silicon nitride, or may include a composite layer of an organic material layer and/or an inorganic material.
The thin film transistor may control the emission of each sub-pixel, or may control the amount of emission when each sub-pixel emits. The thin film transistor may include a semiconductor layer, a gate electrode, a source electrode, and a drain electrode. The semiconductor layer may be formed of an amorphous silicon layer, a metal oxide, or a polysilicon layer, or may be formed of an organic semiconductor material. In some embodiments, the semiconductor layer includes a channel region and source and drain regions doped with a dopant.
The semiconductor layer may be covered with a gate insulating layer, and the gate electrode may be disposed on the gate insulating layer. In general, the gate insulating layer may cover the entire surface of the base substrate 122. In some embodiments, the gate insulating layer may be formed by patterning. The gate insulating layer may be formed of silicon oxide, silicon nitride, or other insulating organic or inorganic materials in consideration of adhesion to adjacent layers, formability of a stack target layer, and surface flatness. The gate electrode may be covered by an interlayer insulating layer formed of silicon oxide, silicon nitride, and/or other suitable insulating organic or inorganic materials. A portion of the gate insulating layer and the interlayer insulating layer may be removed, and a contact hole may be formed after the removal to expose a predetermined region of the semiconductor layer. The source and drain electrodes may contact the semiconductor layer via the contact holes.
Based on the above-mentioned organic electroluminescent display panel, embodiments of the present invention further provide a display device, in some embodiments, the display device may be a display terminal, such as a tablet computer, and in other embodiments, the display device may also be a mobile communication terminal, such as a mobile phone terminal.
In some embodiments, the display device includes an organic electroluminescent display panel and a control unit for transmitting a display signal to the display panel.
In the organic electroluminescent display panel and the display device, by embedding a part of the pixel electrode 16 in the passivation layer 14 and embedding a part of the cathode 11 in the pixel defining layer 18, on one hand, stress can be effectively dispersed when the display panel is impacted or bent; on the other hand, the contact area between the cathode 11 and the pixel defining layer 18 and the contact area between the pixel electrode 16 and the passivation layer 14 are increased, so that the cathode 11 and the pixel defining layer 18 and the pixel electrode 16 and the passivation layer 14 have better bonding force, and the adhesion of the electrodes is improved compared with the conventional design in which the film layers are adhered by van der waals force. Therefore, the cathode 11 and the pixel electrode 16 are effectively prevented from being broken or partially stripped, and the reliability of the bending resistance and the falling impact strength of the OLED display panel is effectively improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An organic electroluminescent display panel, comprising:
a thin film transistor disposed on the substrate;
a passivation layer formed on the thin film transistor and configured to have a contact hole exposing a drain electrode of the thin film transistor;
the pixel electrode is formed on the passivation layer and is connected to the drain electrode of the thin film transistor through the contact hole;
a pixel defining layer formed on the passivation layer and defining a pixel defining opening for exposing at least a portion of the pixel electrode;
wherein a portion of at least one of the pixel electrodes is embedded within the passivation layer; the pixel electrode has an active area exposed by the pixel defining opening, and the portion of the pixel electrode embedded in the passivation layer is located in an active area and a non-active area of the pixel electrode.
2. The organic electroluminescent display panel according to claim 1, further comprising a first recess formed on the passivation layer;
portions of the pixel electrode are located within the first recess.
3. The organic electroluminescent display panel according to claim 2, wherein the depth of the first recess is greater than the film thickness of the pixel electrode located in the first recess.
4. The panel according to claim 3, wherein a side of the portion of the pixel electrode filled in the first recess portion facing away from the passivation layer forms a recess;
the pixel defining layer is embedded in the recess.
5. The organic electroluminescent display panel according to any one of claims 1 to 3,
portions of the pixel definition layer are embedded within the passivation layer.
6. The organic electroluminescent display panel according to claim 5, further comprising a groove formed on the passivation layer; the pixel definition layer covers in the groove;
each of the grooves is disposed around at least a portion of one of the pixel electrodes.
7. The organic electroluminescent display panel according to any one of claims 1 to 3, further comprising a cathode electrode covering the pixel defining layer;
a portion of the cathode is embedded within the pixel defining layer.
8. The organic electroluminescent display panel according to claim 7, further comprising a second recess formed in a surface of the pixel defining layer on a side facing away from the passivation layer;
a portion of the cathode is located within the second recess.
9. The organic electroluminescent display panel according to claim 8, further comprising a first recess formed on the passivation layer;
a portion of the pixel electrode is located within the first recess;
the second concave part faces the orthographic projection of the passivation layer and is spaced from the first concave part.
10. A display device comprising the organic electroluminescent display panel according to any one of claims 1 to 9.
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| CN109670475B (en) * | 2018-12-28 | 2020-11-03 | 上海天马有机发光显示技术有限公司 | Light sensing module and display panel |
| TWI706206B (en) * | 2019-03-15 | 2020-10-01 | 友達光電股份有限公司 | Pixel structure |
| CN110112195A (en) * | 2019-04-30 | 2019-08-09 | 武汉华星光电半导体显示技术有限公司 | Display panel |
| CN110416281A (en) * | 2019-08-26 | 2019-11-05 | 上海天马微电子有限公司 | Display panel and display device |
| CN110828484A (en) * | 2019-11-19 | 2020-02-21 | 京东方科技集团股份有限公司 | Display panel, manufacturing method thereof and display device |
| CN111063715B (en) * | 2019-12-19 | 2022-07-12 | 武汉华星光电半导体显示技术有限公司 | Flexible display panel |
| CN111769215B (en) * | 2020-06-23 | 2021-10-08 | 武汉华星光电半导体显示技术有限公司 | Display panel manufacturing method and display panel |
| CN111864101A (en) * | 2020-07-06 | 2020-10-30 | 武汉华星光电半导体显示技术有限公司 | Display panel and manufacturing method thereof |
| CN113823664B (en) * | 2021-08-16 | 2023-04-07 | 深圳市华星光电半导体显示技术有限公司 | Display panel and manufacturing method thereof |
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| JPWO2005107327A1 (en) * | 2004-04-30 | 2008-03-21 | 三洋電機株式会社 | Luminous display |
| KR20160066650A (en) * | 2014-12-02 | 2016-06-13 | 삼성디스플레이 주식회사 | Fabrication method of display device and display device |
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