Display substrate, preparation method thereof, display panel and display device

Abstract

The application provides a display substrate, a preparation method thereof, a display panel and a display device. The display substrate comprises a substrate, a light-emitting device layer on the substrate, and an encapsulation structure on a side of the light-emitting device layer away from the substrate. The film layer farthest from the substrate in the light-emitting device layer is a light extraction layer. The encapsulation structure comprises a first inorganic encapsulation layer, an organic encapsulation layer on a side of the first inorganic encapsulation layer away from the substrate, and a second inorganic encapsulation layer on a side of the organic encapsulation layer away from the substrate; the first inorganic encapsulation layer comprises a plurality of sub-film layers, and the sub-film layer farthest from the light extraction layer is a low-stress inorganic layer, and the stress of the low-stress inorganic layer is smaller than the stress of the second inorganic encapsulation layer. The display panel comprises the display substrate. The display device comprises the display panel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a display substrate, a preparation method thereof, a display panel and a display device. BACKGROUND

[0002] OLED (Organic Light-Emitting Diode) display has a wide range of applications in the fields of display, lighting and smart wear, due to its self-emission, low driving voltage, high emission efficiency, short response time, high definition and contrast, wide temperature range, and flexible display. The existing OLED display device has a low service life. SUMMARY

[0003] The first aspect of the embodiments of the present application provides a display substrate. The display substrate comprises:

[0004] a substrate;

[0005] a light-emitting device layer on the substrate, the film layer farthest from the substrate in the light-emitting device layer being a light extraction layer;

[0006] an encapsulation structure on the side of the light-emitting device layer away from the substrate, the encapsulation structure comprising a first inorganic encapsulation layer, an organic encapsulation layer on the side of the first inorganic encapsulation layer away from the substrate, and a second inorganic encapsulation layer on the side of the organic encapsulation layer away from the substrate; the first inorganic encapsulation layer comprises a plurality of sub-film layers, the sub-film layer farthest from the light extraction layer being a low-stress inorganic layer, the stress of the low-stress inorganic layer being less than the stress of the second inorganic encapsulation layer.

[0007] In one embodiment, the material of the low-stress inorganic layer farthest from the light extraction layer comprises silicon oxynitride.

[0008] In one embodiment, the first inorganic encapsulation layer comprises at least two low-stress inorganic layers, and the distance from the at least two low-stress inorganic layers to the light extraction layer is less than the distance from other sub-film layers of the first inorganic encapsulation layer to the light extraction layer.

[0009] In one embodiment, the at least two low-stress inorganic layers comprise two layers of silicon oxynitride film layers and a silicon nitride film layer between the two layers of silicon oxynitride film layers.

[0010] In one embodiment, the plurality of sub-film layers comprise at least one low-stress inorganic layer, the first inorganic encapsulation layer further comprises a first inorganic material layer on the side of the at least one low-stress inorganic layer away from the substrate, and the material of the first inorganic material layer comprises metal oxide.

[0011] In one embodiment, the display substrate further comprises a color filter layer, the color filter layer comprises a plurality of color resist arranged at intervals and a black matrix arranged between adjacent color resist; the color filter layer is multiplexed as the organic encapsulation layer; the first inorganic encapsulation layer further comprises a second inorganic material layer arranged between the first inorganic material layer and the organic encapsulation layer.

[0012] In one embodiment, the first inorganic encapsulation layer further comprises a third inorganic material layer arranged between the first inorganic material layer and the low-stress inorganic layer, the third inorganic material layer has a density greater than the low-stress inorganic layer.

[0013] In one embodiment, the display substrate further comprises a color filter layer, the color filter layer comprises a plurality of color resist arranged at intervals and a black matrix arranged between adjacent color resist; the color filter layer is multiplexed as the organic encapsulation layer.

[0014] In one embodiment, in a direction away from the substrate, the first inorganic encapsulation layer comprises a first low-stress inorganic layer, a second low-stress inorganic layer, a third low-stress inorganic layer, a third inorganic material layer, a first inorganic material layer and a second inorganic material layer arranged in sequence; the materials of the first low-stress inorganic layer and the third low-stress inorganic layer are silicon oxynitride, the materials of the second low-stress inorganic layer, the third inorganic material layer and the second inorganic material layer are silicon nitride; the material of the first inorganic material layer comprises metal oxide.

[0015] In one embodiment, the thickness of the first low-stress inorganic layer and the thickness of the third low-stress inorganic layer are respectively less than the thickness of the second low-stress inorganic layer, and the thickness of the first inorganic material layer and the thickness of the second inorganic material layer are respectively less than the thickness of the third inorganic material layer.

[0016] In one embodiment, the display substrate comprises a display area and a binding area arranged at least on one side of the display area; the light emitting device layer and the encapsulation structure are arranged in an area outside the binding area.

[0017] The second aspect of the embodiments of the present application provides a display panel, the display panel comprising the display substrate described above.

[0018] The third aspect of the embodiments of the present application provides a display device, the display device comprising the display panel described above.

[0019] The fourth aspect of the embodiments of the present application provides a preparation method of a display substrate, the preparation method comprising:

[0020] providing a substrate;

[0021] forming a light emitting device layer on the substrate, a film layer in the light emitting device layer farthest from the substrate being a light extraction layer;

[0022] forming, in sequence, a first inorganic encapsulation layer, an organic encapsulation layer on a side of the first inorganic encapsulation layer facing away from the substrate, and a second inorganic encapsulation layer on a side of the organic encapsulation layer facing away from the substrate on a side of the light emitting device layer facing away from the substrate; the first inorganic encapsulation layer comprising a plurality of sub-film layers, a sub-film layer farthest from the light extraction layer being a low-stress inorganic layer, the low-stress inorganic layer having a stress smaller than a stress of the second inorganic encapsulation layer.

[0023] In one embodiment, the display substrate comprises a display area and a binding area on at least one side of the display area; the light emitting device layer is located in a region outside the binding area;

[0024] The forming, in sequence, a first inorganic encapsulation layer, an organic encapsulation layer on a side of the first inorganic encapsulation layer facing away from the substrate, and a second inorganic encapsulation layer on a side of the organic encapsulation layer facing away from the substrate on a side of the light emitting device layer facing away from the substrate comprises:

[0025] forming a first inorganic encapsulation layer on the substrate in the display area and the binding area, and etching the first inorganic encapsulation layer to remove a portion of the first inorganic encapsulation layer in the binding area;

[0026] forming a color filter layer on the first inorganic encapsulation layer in the region outside the binding area, the color filter layer comprising a plurality of color resist arranged at intervals and a black matrix between adjacent color resist; the color filter layer being multiplexed as the organic encapsulation layer;

[0027] forming a second inorganic encapsulation layer on the organic encapsulation layer in the display area and the binding area, and etching the second inorganic encapsulation layer to remove a portion of the second inorganic encapsulation layer in the binding area.

[0028] In one embodiment, the step of forming the first inorganic encapsulation layer comprises:

[0029] forming at least one low-stress inorganic layer;

[0030] forming a first inorganic material layer on a side of the low-stress inorganic layer facing away from the substrate by atomic layer deposition process, the first inorganic material layer comprising a metal oxide.

[0031] The display substrate, the preparation method thereof, the display panel and the display device provided by the embodiments of the present application have the following advantages: the sub-film layer of the first inorganic encapsulation layer that is closest to the light extraction layer of the light-emitting device layer is a low-stress film layer, and the stress of the low-stress film layer is smaller than the stress of the second inorganic encapsulation layer, so the stress difference between the low-stress film layer of the first inorganic encapsulation layer that is closest to the light extraction layer and the light extraction layer is small, the light extraction layer is prevented from being pulled and deformed due to a large stress difference between the sub-film layer of the first inorganic encapsulation layer that is closest to the light extraction layer and the light extraction layer, and the service life of the light-emitting device layer is affected, and therefore the service life of the display panel can be improved.

[0032] It should be understood that the general description above and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0034] Figure 1 is a partial cross-sectional view of a display substrate provided by an embodiment of the present application;

[0035] Figure 2 is a partial scanning electron microscope (SEM) image of a display substrate provided by an embodiment of the present application in a split-open state;

[0036] Figure 3 is a top view of a display substrate provided by an embodiment of the present application;

[0037] Figure 4 is a partial cross-sectional view of a display substrate provided by an embodiment of the present application;

[0038] Figure 5 is a flowchart of a preparation method of a display substrate provided by an embodiment of the present application;

[0039] Figure 6 is a partial cross-sectional view of a first intermediate structure of a display substrate provided by an embodiment of the present application;

[0040] Figure 7 is a partial cross-sectional view of a second intermediate structure of a display substrate provided by an embodiment of the present application;

[0041] Figure 8 is a partial cross-sectional view of a third intermediate structure of a display substrate provided by an embodiment of the present application;

[0042] Figure 9 and Figure 10 is a curve diagram obtained by detecting the height of the part of the second intermediate structure located in the display area and the part located in the bonding area by using an atomic force microscope (AFM);

[0043] Figure 11 FIG. 1 is a partial cross-sectional view of a display panel according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] The exemplary embodiments will be described in detail herein below with reference to the accompanying drawings. In the following description, unless otherwise indicated, the same reference numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments are not representative of all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0045] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the present application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0046] It should be understood that the use of "first", "second", and / or like designations in the present application and claims are not intended to limit one implementation over another, unless otherwise indicated. Rather, such designations may be used herein as a nomenclature to distinguish between different elements, features, structures and / or acts. Similarly, the use of "one" or "a" or "an" are not intended to limit the quantity of such elements, feature, structures and / or acts to one, unless otherwise indicated. Unless otherwise indicated, the terms "front", "back", "up", "down", and the like in the description and in the claims can refer to an orientation as shown in the figures, or can refer to an orientation opposite to that shown in the figures, or can refer to an orientation that is intermediate to that shown in the figures. The terms "including", "containing", "comprising", and the like are meant to be broad terms in that they mean the elements or objects following the term are included and can be some of the elements or objects or all of the elements or objects listed. The terms "first", "second", and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

[0047] The display substrate, the manufacturing method of the display substrate, the display panel and the display device according to the embodiments of the present application will be described in detail below with reference to the drawings. The features in the following embodiments and implementation manners can be complementary or combined with each other without conflict.

[0048] The display substrate according to an embodiment of the present application is provided. Referring to FIG. 1, the display substrate includes a substrate 10, a light emitting device layer 20, and an encapsulation structure 30. Figure 1

[0049] ​The light-emitting device layer 20 is located on the substrate 10, and the film layer in the light-emitting device layer 20 farthest from the substrate 10 is a light extraction layer 21. The encapsulation structure 30 is located on a side of the light-emitting device layer 20 away from the substrate 10, and the encapsulation structure 30 includes a first inorganic encapsulation layer 31, an organic encapsulation layer 32 located on a side of the first inorganic encapsulation layer 31 away from the substrate 10, and a second inorganic encapsulation layer 33 located on a side of the organic encapsulation layer 32 away from the substrate 10. The first inorganic encapsulation layer 31 includes a plurality of sub-film layers, and the sub-film layer farthest from the light extraction layer 21 is a low-stress inorganic layer 301, and the stress of the low-stress inorganic layer 301 is less than the stress of the second inorganic encapsulation layer 33.

[0050] The display substrate provided by the embodiment of the present application has the following advantages: the sub-film layer farthest from the light extraction layer 21 in the first inorganic encapsulation layer 31 is a low-stress inorganic layer 301, and the stress of the low-stress inorganic layer 301 is less than the stress of the second inorganic encapsulation layer 33, so the stress difference between the low-stress inorganic layer 301 farthest from the light extraction layer 21 in the first inorganic encapsulation layer 31 and the light extraction layer 21 is small, which can prevent the sub-film layer farthest from the light extraction layer 21 in the first inorganic encapsulation layer 31 from being pulled and deformed due to a large stress difference between the sub-film layer and the light extraction layer 21, thereby affecting the service life of the light-emitting device layer 20, and the service life of the display panel can be improved.

[0051] In an embodiment, the substrate 10 can be a flexible substrate or a rigid substrate. The material of the flexible substrate can include one or more of polyimide, polyethylene terephthalate, and polycarbonate. The material of the rigid substrate can be glass, silicon, or the like.

[0052] In an embodiment, the light-emitting device layer 20 further includes a first electrode 22, a light-emitting material layer 23 located on a side of the first electrode 22 away from the substrate 10, and a second electrode 24 located on a side of the light-emitting material layer 23 away from the substrate 10. The light extraction layer 21 is located on a side of the second electrode 24 away from the substrate 10. The first electrode 22 can be an anode, the second electrode 24 can be a cathode, and the second electrode 24 can be a surface electrode connected in one piece. The light-emitting material layer 23 can be an organic light-emitting material layer.

[0053] In an embodiment, the light-emitting device layer 20 includes a plurality of sub-pixels, and the first electrodes 22 of the sub-pixels are arranged at intervals. The light-emitting device layer 20 can include sub-pixels of at least three different light-emitting colors, for example, red sub-pixels, green sub-pixels, and blue sub-pixels.

[0054] In one embodiment, the display substrate 100 further comprises a pixel defining layer provided with a plurality of pixel openings. The pixel defining layer is located on the side of the first electrode 22 facing away from the substrate 10, exposing at least part of the first electrode 22. The light emitting material layer 23 is at least partially located in the pixel openings. The second electrode 24 covers the pixel defining layer and the pixel openings.

[0055] In one embodiment, the low stress inorganic layer 301 in the first inorganic encapsulation layer 31 which is closest to the light extraction layer 21 of the light emitting device layer 20 is in direct contact with the light extraction layer 21. In this way, the stress difference between the low stress inorganic layer 301 which is closest to the light extraction layer 21 in the first inorganic encapsulation layer 31 and the light extraction layer 21 is further reduced, the light extraction layer 21 is more effectively prevented from being deformed due to pulling, and the service life of the display substrate is further improved.

[0056] In one embodiment, the stress of the low stress inorganic layer 301 is less than or equal to 100 MPa.

[0057] In one embodiment, the material of the low stress inorganic layer 301 which is closest to the light extraction layer 21 comprises silicon oxynitride. When the material of the low stress inorganic layer 301 comprises silicon oxynitride, the stress of the low stress inorganic layer 301 is smaller, and the stress difference between the low stress inorganic layer 301 and the light extraction layer 21 is more effectively reduced. Furthermore, when the material of the low stress inorganic layer 301 comprises silicon oxynitride, the adhesion of the low stress inorganic layer 301 is better, the adhesion between the low stress inorganic layer 301 and the light extraction layer 21 is improved, and peeling between the two is avoided; at the same time, the thermal expansion coefficient of the low stress inorganic layer 301 is smaller, the difference in thermal expansion coefficient between the low stress inorganic layer 301 and the light extraction layer 21 is reduced, peeling between the two due to a large difference in thermal expansion coefficient caused by a temperature rise during the preparation and working of the display substrate is prevented, and the pulling effect on the light extraction layer 21 is also improved. In some embodiments, the material of the light extraction layer 21 is silicon oxynitride.

[0058] In one embodiment, the first inorganic encapsulation layer 31 comprises at least two low stress inorganic layers 301, and the distance from the at least two low stress inorganic layers 301 to the light extraction layer 21 is smaller than the distance from other sub-film layers of the first inorganic encapsulation layer 31 to the light extraction layer 21. That is, the at least two low stress inorganic layers 301 of the first inorganic encapsulation layer 31 are located on the side closer to the light extraction layer 21 than other sub-film layers (sub-film layers with higher stress). In this way, the at least two sub-film layers which are closest to the light extraction layer 21 in the first inorganic encapsulation layer 31 are low stress inorganic layers 301, the stress difference between the first inorganic encapsulation layer 31 and the light extraction layer 21 is further reduced, the pulling effect on the light extraction layer 21 is further reduced, and the service life of the light extraction layer 21 is improved.

[0059] In one embodiment, the at least two low-stress inorganic layers include two layers of silicon oxynitride film and a silicon nitride film layer between the two layers of the silicon oxynitride film. That is, the at least two low-stress inorganic layers include three low-stress inorganic layers 301. Figure 1 In the illustrated embodiment, the at least two low-stress inorganic layers include a first low-stress inorganic layer 311, a second low-stress inorganic layer 312 located on a side of the first low-stress inorganic layer 311 away from the substrate 10, and a third low-stress inorganic layer 313 located on a side of the second low-stress inorganic layer 312 away from the substrate 10, the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 are both silicon oxynitride film layers, and the second low-stress inorganic layer 312 is a silicon nitride film layer. In this way, the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 have smaller stress, smaller thermal expansion coefficient, and better adhesion, the second low-stress inorganic layer 312 has better compactness and better water and oxygen barrier effect, and the cooperation of the three film layers can make the three low-stress inorganic layers 301 of the first inorganic encapsulation layer 31 and the light extraction layer 21 have smaller stress difference, smaller thermal expansion coefficient difference, better adhesion, and better water and oxygen barrier effect of the first inorganic encapsulation layer 31 and the light extraction layer 21. In some example embodiments, the material of the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 is silicon oxynitride, and the material of the second low-stress inorganic layer 312 is silicon nitride.

[0060] In one embodiment, the low-stress inorganic layer 301 of the first inorganic encapsulation layer 31 is prepared by a CVD (chemical vapor deposition) process.

[0061] In one embodiment, when the material of the low-stress inorganic layer includes silicon oxynitride, compared with a high-stress inorganic layer including a silicon oxynitride material, the low-stress inorganic layer has smaller density, looser film layer, and lower refractive index, and the interaction force between atoms is attractive; and the oxygen atom content in the low-stress inorganic layer is increased, and the nitrogen atom content is reduced; and in the preparation process of the low-stress inorganic layer, the N2O content is increased, and the NH3 content is reduced.

[0062] In some embodiments, when the material of the low-stress inorganic layer includes silicon nitride, compared with a high-stress inorganic layer including a silicon nitride material, the low-stress inorganic layer has smaller density, looser film layer, and lower refractive index; and the nitrogen atom content in the low-stress inorganic layer is less. In the preparation process of the low-stress inorganic layer, N2 and H2 as carrier gases are interchanged, the N2 content is increased, and the H2 content is reduced, because H2 can saturate the dangling bonds of the film layer and enhance the plasma characteristics in the preparation process of the low-stress inorganic layer, and increasing the N2 content can reduce this effect, so that the nitrogen atom content in the low-stress inorganic layer is reduced.

[0063] In one embodiment, the plurality of sub-film layers includes at least one low-stress inorganic layer 301, and the first inorganic encapsulation layer 31 further includes a first inorganic material layer 314 located on a side of the at least one low-stress inorganic layer 301 away from the substrate 10, and the material of the first inorganic material layer 314 includes a metal oxide. When the material of the first inorganic material layer 314 includes a metal oxide, the first inorganic material layer 314 can be formed by an atomic layer deposition process, and the film layer of the first inorganic material layer 314 has good compactness, which is conducive to improving the encapsulation effect of the display substrate. In some embodiments, the material of the first inorganic material layer 314 includes aluminum oxide. For example, the material of the first inorganic material layer 314 is aluminum oxide.

[0064] In one embodiment, the first inorganic material layer 314 includes at least one atomic film layer. When the plurality of sub-film layers of the first inorganic encapsulation layer 31 includes a plurality of low-stress inorganic layers 301, the first inorganic material layer 314 is located on a side of the plurality of low-stress inorganic layers 301 away from the substrate 10, that is, the plurality of low-stress inorganic layers 301 are located on a side of the first inorganic material layer 314 facing the substrate 10. The atomic film layer has good compactness and good coverage of the underlying film layer, and can reduce the gap between the atomic film layer and the underlying film layer. Therefore, the first inorganic material layer 314 including the atomic film layer has good compactness and good blocking effect of water vapor and oxygen, which is conducive to improving the encapsulation effect of the display substrate.

[0065] In one embodiment, the first inorganic material layer 314 is formed by an atomic layer deposition process. The oxide layer prepared by the atomic layer deposition process is an atomic layer film layer, and therefore the first inorganic encapsulation layer 31 includes an atomic film layer. The atomic layer film layer has high coverage of the pores on the surface of the underlying film layer, can reduce the pores between the atomic layer film layer and the underlying film layer, and the atomic layer film layer formed by the atomic layer deposition process is deposited on the underlying film layer in a chemical adsorption manner, and has high adhesion with the underlying film layer. Therefore, the first inorganic material layer 314 has high adhesion with the underlying sub-film layer, which is conducive to improving the encapsulation effect of the display substrate 100. In some embodiments, when the first inorganic material layer 314 is formed by the atomic layer deposition process, the first inorganic material layer 314 can include a plurality of single-atom film layers.

[0066] In one embodiment, the first inorganic encapsulation layer 31 further comprises a second inorganic material layer 315 between the first inorganic material layer 314 and the organic encapsulation layer 32. The second inorganic material layer 315 can prevent the first inorganic encapsulation layer 31 from being damaged during etching of the organic encapsulation layer 32. The second inorganic material layer 315 can have a higher density than the low-stress inorganic layer 301 to further improve the water-oxygen barrier effect of the first inorganic encapsulation layer 31. The second inorganic material layer 315 can comprise silicon nitride, for example. The second inorganic material layer 315 can be prepared by a CVD process.

[0067] In one embodiment, the first inorganic encapsulation layer 31 further comprises a third inorganic material layer 316 between the first inorganic material layer 314 and the low-stress inorganic layer 301, the third inorganic material layer 316 having a higher density than the low-stress inorganic layer 301. By providing the third inorganic material layer 316 having a higher density, the third inorganic material layer 316 covers the voids of the low-stress inorganic layer 301 thereunder, preventing the poor water-oxygen barrier effect of the low-stress inorganic layer 301 due to its poor density, and improving the water-oxygen barrier performance of the first inorganic encapsulation layer 31. The third inorganic material layer 316 and the first inorganic material layer 314 can both cover the voids of the low-stress inorganic layer 301, and the combination of the two can make the water-oxygen barrier effect of the first inorganic encapsulation layer 31 better. The third inorganic material layer 316 can be prepared by a CVD process. Figure 1 In the illustrated embodiment, the third inorganic material layer 316 is between the first inorganic material layer 314 and the third low-stress inorganic layer 313.

[0068] In some embodiments, the third inorganic material layer 316 comprises silicon nitride. Silicon nitride has good density, and thus the third inorganic material layer 316 can have a high density. The third inorganic material layer 316 can comprise silicon nitride.

[0069] In one embodiment, as shown in FIG. 1, the first inorganic encapsulation layer 31 further comprises a second inorganic material layer 315 between the first inorganic material layer 314 and the organic encapsulation layer 32. The second inorganic material layer 315 can prevent the first inorganic encapsulation layer 31 from being damaged during etching of the organic encapsulation layer 32. The second inorganic material layer 315 can have a higher density than the low-stress inorganic layer 301 to further improve the water-oxygen barrier effect of the first inorganic encapsulation layer 31. The second inorganic material layer 315 can comprise silicon nitride, for example. The second inorganic material layer 315 can be prepared by a CVD process. Figure 1As shown, in the direction away from the substrate 10, the first inorganic packaging layer 31 comprises a first low-stress inorganic layer 311, a second low-stress inorganic layer 312, a third low-stress inorganic layer 313, a third inorganic material layer 316, a first inorganic material layer 314 and a second inorganic material layer 315 which are sequentially stacked; the materials of the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 are silicon oxynitride, the materials of the second low-stress inorganic layer 312, the third inorganic material layer 316 and the second inorganic material layer 315 are silicon nitride; and the material of the first inorganic material layer 314 comprises metal oxide. In this way, the number of sub-film layers of the first inorganic packaging layer 31 is large, the path of water and oxygen in the process of propagating through the first inorganic packaging layer 31 to the light-emitting device layer 20 is long, and it is not easy for water and oxygen to invade the light-emitting device layer 20, which can improve the performance of the first inorganic packaging layer 31 in blocking water and oxygen; the material of the first inorganic material layer 314 comprises metal oxide, so the first inorganic material layer 314 can be formed by an atomic layer deposition process, that is, the first inorganic material layer 314 has good compactness, which can improve the performance of the first inorganic packaging layer in blocking water and oxygen; the distances between the first low-stress inorganic layer 311, the second low-stress inorganic layer 312 and the third low-stress inorganic layer 313 and the light extraction layer 21 are small, the stress difference and the thermal expansion coefficient difference between them and the light extraction layer 21 are small, which can reduce the pulling force on the light extraction layer 21, prevent the light extraction layer 21 from deforming, and improve the service life of the display substrate.

[0070] Further, the thickness of the first low-stress inorganic layer 311 and the thickness of the third low-stress inorganic layer 313 are respectively smaller than the thickness of the second low-stress inorganic layer 312, and the thickness of the first inorganic material layer 314 and the thickness of the second inorganic material layer 315 are respectively smaller than the thickness of the third inorganic material layer 316. In this way, the packaging effect of the first inorganic packaging layer 31 can be ensured on the premise of effectively reducing the pulling effect on the light extraction layer 21.

[0071] Further, the thickness of the first low-stress inorganic layer 311 and the thickness of the third low-stress inorganic layer 313 are respectively smaller than the thickness of the second low-stress inorganic layer 312, and the thickness of the first inorganic material layer 314 and the thickness of the second inorganic material layer 315 are respectively smaller than the thickness of the third inorganic material layer 316. In this way, the packaging effect of the first inorganic packaging layer 31 can be ensured on the premise of effectively reducing the pulling effect on the light extraction layer 21.

[0072] In some embodiments, the thicknesses of the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 are, for example, 0.05 μm, 0.07 μm, 0.09 μm, 0.1 μm, etc.; the thickness of the second low-stress inorganic layer 312 is, for example, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, etc.; the thickness of the first inorganic material layer 314 is, for example, 0.05 μm, 0.07 μm, 0.09 μm, 0.1 μm, etc.; the thickness of the second inorganic material layer 315 is, for example, 0.1 μm, 0.12 μm, 0.15 μm, 0.17 μm, 0.2 μm, etc.; and the thickness of the third inorganic material layer 316 is, for example, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, etc.

[0073] Figure 2 This is a partial scanning electron microscope (SEM) image of a display substrate in a cut-open state, provided in an exemplary embodiment of this application. For example... Figure 2 As shown, the pixel defining layer 50 is located on the first electrode 22, and the light-emitting material layer 23 is partially located on the first electrode 22 and partially located on the sidewall of the pixel defining layer 50; the second electrode 24 covers the light-emitting material layer 23; the light extraction layer 21 is located on the first electrode 22, and the thickness of the light extraction layer 21 is relatively thin; the thickness of the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 are approximately equal, and the third inorganic material layer 316 is in direct contact with the third low-stress inorganic layer 313.

[0074] In one embodiment, the display substrate 100 further includes a color filter layer 40, which includes a plurality of spaced-apart color resists 41 and a black matrix 42 located between adjacent color resists 41. The color filter layer 40 is reused as the organic encapsulation layer 32. The color filter layer 40 enables color display on the display substrate and filters the light emitted from the light-emitting device layer 20, preventing stray light from escaping and improving the display effect of the display substrate 100. Furthermore, the color filter layer 40 reduces the amount of light reflected after external light enters the display substrate, enhancing the user experience. Reusing the color filter layer 40 as an organic encapsulation layer in the encapsulation structure 30 simplifies the film structure of the display substrate, helps reduce its thickness, and improves its light extraction efficiency. The color filter layer 40 also has good film-forming properties and surface flatness, contributing to improved film flatness in the encapsulation structure 30. The color filter layer 40 can encapsulate the particles of the underlying inorganic layer, resulting in better film uniformity in the second inorganic encapsulation layer 33 and improving the encapsulation performance of the encapsulation structure.

[0075] In one embodiment, the color resist 41 of the color filter layer 40 corresponds to a sub-pixel one-to-one, and the orthographic projection of the color resist 41 on the substrate 10 covers the orthographic projection of the corresponding sub-pixel on the substrate 10. The light-emitting color of the sub-pixel is the same as the color of the corresponding color resist 41. When the light-emitting device layer 20 includes red sub-pixels, green sub-pixels, and blue sub-pixels, the color filter layer 40 includes red color resist, green color resist, and blue color resist.

[0076] In the process of preparing the color filter layer 40, color resists 41 of the same color can be formed at the same process step. Specifically, a full-surface color resist material can be coated first, and then the color resist material is patterned to obtain a plurality of color resists 41 of the same color. The color resist material can be patterned by an exposure and development process. The second inorganic material layer 315 between the color filter layer 40 and the first inorganic material layer 314 can prevent the first inorganic material layer 314 from being corroded by a developing solution when the color resist is developed, thereby protecting the first inorganic material layer 314 and helping to improve the water and oxygen blocking performance of the first inorganic material layer.

[0077] In one embodiment, the thickness of the color filter layer 40 ranges from 2.5 μm to 3.5 μm. In this way, it can be avoided that the thickness of the color filter layer 40 is too small, which results in a poor particle covering effect of the inorganic layer below the color filter layer 40, and it can also be avoided that the thickness of the color filter layer 40 is too large, which leads to an increase in the thickness of the display substrate, which is not conducive to the thinning of the display substrate. In some embodiments, the thickness of the color filter layer 40 is, for example, 2.5 μm, 2.8 μm, 3.0 μm, 3.2 μm, 3.5 μm, etc.

[0078] In one embodiment, the material of the second inorganic encapsulation layer 33 includes silicon nitride. In this way, the second inorganic encapsulation layer 33 has better compactness and better water and oxygen blocking effect. The material of the second inorganic encapsulation layer 33 can be silicon nitride.

[0079] In one embodiment, the thickness of the second inorganic encapsulation layer 33 ranges from 0.6 μm to 0.8 μm. In this way, it can be avoided that the thickness of the second inorganic encapsulation layer 33 is too small, which results in a poor water and oxygen blocking effect, and it can also be avoided that the thickness of the second inorganic encapsulation layer 33 is too large, which leads to an increase in the thickness of the display substrate 100. In some embodiments, the thickness of the second inorganic encapsulation layer 33 is, for example, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, etc.

[0080] In one embodiment, the display substrate further includes a driving circuit layer located between the substrate 10 and the light-emitting device layer 20. The driving circuit layer includes pixel driving circuits located outside the bonding area (mainly located in the display area) and bonding terminals located in the bonding area. The pixel driving circuits of the driving circuit layer correspond one-to-one with the sub-pixels of the light-emitting device layer 20, and each pixel driving circuit is used to drive the corresponding sub-pixel.

[0081] In one embodiment, such as Figure 3 and Figure 4 As shown, the display substrate 100 includes a display area 101 and a bonding area 102 located on at least one side of the display area 101. The light-emitting device layer 20 and the encapsulation structure 30 are both located outside the bonding area 102. If the light-emitting device layer 20 and the encapsulation structure 30 are not formed in the bonding area 102, the bonding terminals of the bonding area 102 are exposed and can be used for bonding with a driver chip or a flexible circuit board. Figure 3 and Figure 4 In the illustrated embodiment, the bonding area 102 is located on one side of the display area 101; specifically, the bonding area 102 may be located on the underside of the display area 101. The light-emitting device layer 20 may be located only in the display area 101.

[0082] In one embodiment, the display substrate 100 further includes a fan-out region 103 located between the display region 101 and the bonding region 102. The encapsulation structure 30 may cover the display region 101 and the fan-out region 103.

[0083] This application also provides a method for fabricating a display substrate. For example... Figure 5 As shown, the method for preparing the display substrate includes the following steps 110 to 130.

[0084] In step 110, a substrate is provided.

[0085] In step 120, a light-emitting device layer is formed on the substrate, wherein the film layer in the light-emitting device layer that is furthest from the substrate is the light extraction layer.

[0086] Step 120 yields the following result: Figure 6 The first intermediate structure shown. (As shown) Figure 6 As shown, the display substrate 100 includes a display area 101 and a bonding area 102 located on at least one side of the display area 101. The display substrate 100 also includes a fan-out area 103 located between the display area 101 and the bonding area 102. The light-emitting device layer 20 is located only in the display area 101.

[0087] The light emitting device layer 20 further comprises a first electrode 22, a light emitting material layer 23 located on the side of the first electrode 22 away from the substrate 10, and a second electrode 24 located on the side of the light emitting material layer 23 away from the substrate 10. The light extraction layer 21 is located on the side of the second electrode 24 away from the substrate 10. The light emitting device layer 20 is located in the area outside the binding area 102. The light emitting device layer 20 can be located only in the display area 101.

[0088] In step 130, a first inorganic encapsulation layer is formed on the side of the light emitting device layer away from the substrate, an organic encapsulation layer is formed on the side of the first inorganic encapsulation layer away from the substrate, and a second inorganic encapsulation layer is formed on the side of the organic encapsulation layer away from the substrate; the first inorganic encapsulation layer comprises a plurality of sub-film layers, and the sub-film layer with the smallest distance from the light extraction layer is a low-stress inorganic layer, and the stress of the low-stress inorganic layer is smaller than the stress of the second inorganic encapsulation layer.

[0089] In one embodiment, the step 130 of forming a first inorganic encapsulation layer on the side of the light emitting device layer away from the substrate, forming an organic encapsulation layer on the side of the first inorganic encapsulation layer away from the substrate, and forming a second inorganic encapsulation layer on the side of the organic encapsulation layer away from the substrate can comprise the following processes:

[0090] First, a first inorganic encapsulation layer is formed on the substrate in the display area and the binding area, and the first inorganic encapsulation layer is etched to remove the part of the first inorganic encapsulation layer in the binding area.

[0091] Through this step, a second intermediate structure as shown in FIG. 4B can be obtained. As shown in FIG. 4B, the first inorganic encapsulation layer 31 does not cover the binding area 102, and can cover the display area 101 and the fan-out area 103. Figure 7 Figure 7 In this step, a wet etching process can be used to remove the part of the first inorganic encapsulation layer 31 in the binding area 102.

[0092] Subsequently, a color filter layer is formed on the first inorganic encapsulation layer outside the binding area, the color filter layer comprises a plurality of color resist arranged at intervals and a black matrix located between adjacent color resist; the color filter layer is multiplexed as the organic encapsulation layer.

[0093] Through this step, a third intermediate structure as shown in FIG. 5B can be obtained. As shown in FIG. 5B, the color filter layer 40 does not cover the binding area 102, and covers the display area 101 and the fan-out area 103. Figure 8 Figure 8

[0094] ​​​In one embodiment, the color filter layer 40 includes color resist 41 of at least three different colors and black matrix 42 between adjacent color resist 41. In forming the color filter layer 40, color resist 41 of the same color is formed in the same process step, and color resist 41 of different colors is formed in different process steps. The black matrix can be formed first, and then the color resist 41 is formed; or the color resist 41 can be formed first, and then the black matrix 42 is formed. In forming color resist of the same color, a full-surface color resist material can be first coated, and then a photolithography process is used to pattern the color resist material to obtain a plurality of color resist 41 of the same color and arranged in intervals.

[0095] Subsequently, a second inorganic encapsulation layer is formed on the organic encapsulation layer and located in the display area and the binding area, and the second inorganic encapsulation layer is etched to remove the part of the second inorganic encapsulation layer located in the binding area.

[0096] Through the step, the display substrate as shown in FIG. 3B can be obtained. As shown in FIG. 3B, the second inorganic encapsulation layer 33 is located in the area outside the binding area 102. Specifically, the second inorganic encapsulation layer 33 can cover the display area 101 and the fan-out area 103. In this step, a wet etching process can be used to remove the part of the second inorganic encapsulation layer 33 located in the binding area 102. Figure 4 Figure 4 Through the step, the display substrate as shown in FIG. 3B can be obtained. As shown in FIG. 3B, the second inorganic encapsulation layer 33 is located in the area outside the binding area 102. Specifically, the second inorganic encapsulation layer 33 can cover the display area 101 and the fan-out area 103. In this step, a wet etching process can be used to remove the part of the second inorganic encapsulation layer 33 located in the binding area 102.

[0097] The display substrate provided by the embodiments of the present application, in the process of preparing the display substrate 100, since the organic encapsulation layer 32 of the encapsulation structure 30 is a color filter layer, the color filter layer is patterned by a photolithography process, the first inorganic encapsulation layer and the second inorganic encapsulation layer can be patterned by a wet etching process, and the part of each film layer located in the binding area can be removed in the process of patterning the film layers, so that the peeling of adjacent film layers is avoided.

[0098] In one embodiment, the step of forming the first inorganic encapsulation layer includes the following process:

[0099] First, at least one low-stress inorganic layer is formed;

[0100] Subsequently, a first inorganic material layer is formed on the side of the low-stress inorganic layer away from the substrate by an atomic layer deposition process, and the material of the first inorganic material layer includes metal oxide.

[0101] ​The oxide layer prepared by atomic layer deposition (ALD) is an atomic-level film layer; therefore, the first inorganic encapsulation layer 31 includes an atomic film layer. The atomic-level film layer has high coverage over the pores on the surface of the underlying film layer, reducing porosity between the two layers. Furthermore, the atomic-level film layer formed by ALD is deposited on the underlying film layer via chemisorption, resulting in high adhesion between the two layers. Therefore, the first inorganic material layer 314 has high adhesion to the underlying sub-film layer, which helps improve the encapsulation effect of the display substrate 100. The material of the first inorganic material layer may include aluminum oxide.

[0102] In one embodiment, such as Figure 7 As shown, the step of forming the first inorganic encapsulation layer includes the following process: a first low-stress inorganic layer 311, a second low-stress inorganic layer 312, a third low-stress inorganic layer 313, a third inorganic material layer 316, a first inorganic material layer 314, and a second inorganic material layer 315 are sequentially formed on the substrate 10; the first low-stress inorganic layer 311 and the third low-stress inorganic layer 313 are made of silicon oxynitride, and the second low-stress inorganic layer 312, the third inorganic material layer 316, and the second inorganic material layer 315 are made of silicon nitride; the material of the first inorganic material layer 314 includes at least a metal oxide.

[0103] The second intermediate structure prepared by the method provided in this application embodiment was examined using an energy dispersive spectroscopy (EDS) instrument. No nitrogen atoms were detected in the bonding region 102, indicating that the portion of the first inorganic encapsulation layer located in the bonding region 102 was thoroughly etched. The height difference between the portion of the second intermediate structure located in the display region and the portion located in the bonding region was measured using an atomic force microscope (AFM), yielding the following results: Figure 9 and such Figure 10 The graph shown indicates that the thickness of the first inorganic encapsulation layer is approximately 1.0 μm. Figure 9 The portion with a larger height value represents the height of the display area, while the portion with a smaller height value represents the height of the central area of ​​the binding area. △h1 is the height difference between the display area and the central area of ​​the binding area, and the value of △h1 is 1.01μm. Figure 10 The portion with a larger height value represents the height of the display area, while the portion with a smaller height value represents the height of the edge area of ​​the binding area. △h2 is the height difference between the display area and the edge area of ​​the binding area, and the value of △h2 is 1.0μm. Figure 9 and Figure 10 The values ​​on the ordinate only represent the relative height of the film. Figure 9 and Figure 10It can be seen that the portion of the first inorganic encapsulation layer located in the central and edge regions of the bonding area is completely etched away. This indicates that the display substrate prepared by the method provided in this application has a relatively thorough removal of the portion of the first inorganic encapsulation layer located in the bonding area, without affecting the bonding of the bonding area.

[0104] In a display substrate fabrication process, a photoresist delamination process is used to remove the light-emitting device layer and encapsulation structure located in the bonding area. The specific fabrication process is as follows: first, photoresist is formed on the substrate; then, the light-emitting device layer and encapsulation structure are sequentially formed on the photoresist; finally, a laser ablation process is used to thermally expand the photoresist in the bonding area, causing the film layer (including the light-emitting device layer and encapsulation structure) above it to delaminate. In this fabrication process, the high-temperature and plasma processes during the fabrication of the light-emitting device layer and encapsulation structure can damage the photoresist, leading to particle formation and film peeling issues in the film layer of the light-emitting device layer and encapsulation structure formed above the photoresist, affecting the yield of the fabricated display substrate. The display substrate provided in this application embodiment does not require photoresist ablation during the fabrication process, avoiding the low yield problem caused by polar ablation of the photoresist, and helping to improve the yield of the display substrate.

[0105] One hundred display substrates prepared by the method provided in this application and one hundred display substrates prepared by a delamination process were tested. The test temperature was 85°C, the humidity was 85%, and the test duration was 240 hours. After the test, nine display substrates prepared by the method provided in this application showed black spots or poor edge display in the display area, resulting in a yield of 91%. In contrast, the yield of the display substrates prepared by the delamination process was less than 50%. This demonstrates that the preparation method provided in this application can effectively improve the yield of display substrates.

[0106] The display substrate and its preparation method provided in the embodiments of this application belong to the same inventive concept. The descriptions of relevant details and beneficial effects can be found in each other, and will not be repeated here.

[0107] This application also provides a display panel. The display panel includes the display substrate described in any of the above embodiments. Figure 11 As shown, the display panel also includes a cover plate 70 located on the side of the display substrate opposite to the substrate 10. The cover plate 70 protects the display substrate. The cover plate 70 may be a glass cover plate.

[0108] In one embodiment, the display panel further includes an adhesive layer 60 located between the cover plate 70 and the display substrate, wherein the cover plate 70 is bonded to the display substrate by the adhesive layer 60. The adhesive layer 60 may be a transparent optical adhesive.

[0109] The display device provided by the embodiments of the present application may be, for example, a mobile phone, a tablet computer, a television, a notebook computer, a vehicle-mounted device, or any device having a display function.

[0110] In one embodiment, the display device further includes a housing, and the display panel is disposed in the housing.

[0111] The display device provided by the embodiments of the present application may be, for example, a mobile phone, a tablet computer, a television, a notebook computer, a vehicle-mounted device, or any device having a display function.

[0112] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments above, the present application is not intended to be limited thereto. Any person skilled in the art may make some minor changes or modifications to the above disclosed technical contents without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application shall still fall within the scope of the technical solution of the present application.

[0113] The content disclosed in the present patent document contains copyrighted material. The copyright is owned by the copyright owner. The copyright owner does not object to the reproduction of the patent document or the patent disclosure existing in the official records and archives of the Patent and Trademark Office.

Claims

1. A display substrate, characterized by, The display substrate comprises: a substrate; a light-emitting device layer on the substrate, a film layer farthest from the substrate in the light-emitting device layer being a light extraction layer; a packaging structure on a side of the light-emitting device layer away from the substrate, the packaging structure comprising a first inorganic packaging layer, an organic packaging layer on a side of the first inorganic packaging layer away from the substrate, and a second inorganic packaging layer on a side of the organic packaging layer away from the substrate; the first inorganic packaging layer comprises a plurality of sub-film layers, a sub-film layer closest to the light extraction layer being a low-stress inorganic layer, the stress of the low-stress inorganic layer being less than the stress of the second inorganic packaging layer; the plurality of sub-film layers comprise at least one low-stress inorganic layer, the first inorganic packaging layer further comprising a first inorganic material layer on a side of the at least one low-stress inorganic layer away from the substrate, the material of the first inorganic material layer comprising a metal oxide layer; the first inorganic packaging layer further comprising a third inorganic material layer between the first inorganic material layer and the low-stress inorganic layer, the density of the third inorganic material layer being greater than the density of the low-stress inorganic layer.

2. The display substrate of claim 1, wherein, The material of the low-stress inorganic layer closest to the light extraction layer comprises silicon oxynitride. 3.The display substrate of claim 1, wherein, The first inorganic packaging layer comprises at least two low-stress inorganic layers, and the distance of the at least two low-stress inorganic layers to the light extraction layer is less than the distance of other sub-film layers of the first inorganic packaging layer to the light extraction layer.

4. The display substrate of claim 3, wherein, The at least two low-stress inorganic layers comprise two layers of silicon oxynitride film layers and a silicon nitride film layer between the two layers of silicon oxynitride film layers.

5. The display substrate of claim 1, wherein, The display substrate further comprises a color filter layer, the color filter layer comprising a plurality of color resist arranged at intervals and a black matrix between adjacent color resist; the color filter layer is multiplexed as the organic packaging layer; the first inorganic packaging layer further comprises a second inorganic material layer between the first inorganic material layer and the organic packaging layer. 6.The display substrate of claim 1, wherein, The display substrate further comprises a color filter layer, the color filter layer comprising a plurality of color resist arranged at intervals and a black matrix between adjacent color resist; the color filter layer is multiplexed as the organic packaging layer.

7. The display substrate of claim 1, wherein, In a direction away from the substrate, the first inorganic packaging layer comprises a first low-stress inorganic layer, a second low-stress inorganic layer, a third low-stress inorganic layer, a third inorganic material layer, a first inorganic material layer and a second inorganic material layer arranged in sequence; the materials of the first low-stress inorganic layer and the third low-stress inorganic layer are silicon oxynitride, the materials of the second low-stress inorganic layer, the third inorganic material layer and the second inorganic material layer are silicon nitride; the material of the first inorganic material layer comprises a metal oxide. 8.The display substrate of claim 7, wherein, The thickness of the first low-stress inorganic layer and the thickness of the third low-stress inorganic layer are respectively less than the thickness of the second low-stress inorganic layer, and the thickness of the first inorganic material layer and the thickness of the second inorganic material layer are respectively less than the thickness of the third inorganic material layer. 9.The display substrate according to any one of claims 1 to 8, characterized in that, The display substrate comprises a display area and a binding area on at least one side of the display area; the light-emitting device layer and the packaging structure are located in an area outside the binding area.

10. A display panel, characterized by, The display panel comprises the display substrate according to any one of claims 1 to 9.

11. A display device, characterized by comprising: The display device comprises the display panel according to claim 10.

12. A method for preparing a display substrate, characterized in that, The preparation method comprises: providing a substrate; forming a light-emitting device layer on the substrate, the film layer farthest from the substrate in the light-emitting device layer being a light extraction layer; forming, in sequence, a first inorganic encapsulation layer, an organic encapsulation layer on the side of the first inorganic encapsulation layer away from the substrate, and a second inorganic encapsulation layer on the side of the organic encapsulation layer away from the substrate on the side of the light-emitting device layer away from the substrate; the first inorganic encapsulation layer comprises a plurality of sub-film layers, the sub-film layer farthest from the light extraction layer being a low-stress inorganic layer, the stress of the low-stress inorganic layer being less than the stress of the second inorganic encapsulation layer; the step of forming the first inorganic encapsulation layer comprises: forming at least one low-stress inorganic layer; preparing a third inorganic material layer by a CVD process, the density of the third inorganic material layer being greater than the low-stress inorganic layer; forming a first inorganic material layer on the side of the low-stress inorganic layer away from the substrate by an atomic layer deposition process, the material of the first inorganic material layer comprising a metal oxide, the third inorganic material layer being located between the first inorganic material layer and the low-stress inorganic layer.

13. The method of manufacturing the display substrate according to claim 12, wherein The display substrate comprises a display area and a binding area located on at least one side of the display area; the light-emitting device layer is located in the area outside the binding area; the step of forming, in sequence, the first inorganic encapsulation layer, the organic encapsulation layer on the side of the first inorganic encapsulation layer away from the substrate, and the second inorganic encapsulation layer on the side of the organic encapsulation layer away from the substrate on the side of the light-emitting device layer away from the substrate comprises: forming the first inorganic encapsulation layer on the substrate in the display area and the binding area, and etching the first inorganic encapsulation layer to remove the part of the first inorganic encapsulation layer in the binding area; forming a color filter layer outside the binding area on the first inorganic encapsulation layer, the color filter layer comprising a plurality of color resist arranged at intervals and a black matrix located between adjacent color resist; the color filter layer is multiplexed as the organic encapsulation layer; forming the second inorganic encapsulation layer on the organic encapsulation layer in the display area and the binding area, and etching the second inorganic encapsulation layer to remove the part of the second inorganic encapsulation layer in the binding area.

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