Display substrate and display device

Abstract

The application discloses a display substrate and a display device. The display substrate comprises an array substrate, an anode layer and a pixel definition layer on the array substrate, and a reflection layer. The pixel definition layer comprises a first sub-pixel definition layer and a second sub-pixel definition layer arranged in a stack. The first sub-pixel definition layer comprises a first opening exposing at least part of the anode layer. The second sub-pixel definition layer comprises a second opening arranged in alignment with the first opening. The refractive index of the first sub-pixel definition layer is less than that of the second sub-pixel definition layer. The first opening has a first sidewall comprising a first sub-sidewall and a second sub-sidewall. The first sub-sidewall is arranged close to the anode layer, and the second sub-sidewall is arranged on a side of the first sub-sidewall away from the anode layer. The reflection layer covers the first sub-sidewall, and the second sub-pixel definition layer covers the second sub-sidewall and a side of the reflection layer away from the first sub-sidewall. The application can significantly improve the light extraction efficiency while avoiding excessive attenuation of the large-angle brightness.

Description

TECHNICAL FIELD

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

[0002] Organic Light-Emitting Diode (OLED) has the characteristics of low power consumption, fast response speed, wide viewing angle, etc., and its application prospect is broad. At present, due to the influence of whether the substrate is transparent, the top emission OLED device can effectively improve the aperture ratio of the display panel, which is conducive to the integration with the transistor backplane, and can narrow the spectrum and color purity. Therefore, the top emission OLED device has been widely applied to various electronic products, from small electronic products such as smart bracelets, smart watches, smart phones, tablet computers, to large electronic products such as notebook computers, desktop computers, televisions, and each product has put forward the urgent demand for high efficiency and low power consumption.

[0003] Studies have shown that the external quantum efficiency (leakage current, i.e. light output efficiency) of the top emission OLED device is relatively low, generally not more than 30%. The factors affecting the light extraction efficiency include waveguide effect, substrate effect, surface plasmon effect and absorption effect. In order to improve the light extraction efficiency, the above light loss paths need to be solved. SUMMARY

[0004] The present application provides a display substrate and a display device, which can significantly improve the light extraction efficiency of the device while avoiding excessive attenuation of large-angle brightness, thereby improving the overall display effect.

[0005] The present application provides a display substrate, comprising:

[0006] an array substrate;

[0007] an anode layer located on the array substrate;

[0008] a pixel definition layer located on the array substrate and comprising a first sub-pixel definition layer and a second sub-pixel definition layer stacked in sequence; the first sub-pixel definition layer comprises a first opening, and the anode layer is at least partially exposed in the first opening; the second sub-pixel definition layer extends into the first opening and comprises a second opening arranged in register with the first opening; and

[0009] a reflective layer located in the first opening;

[0010] The first sub-pixel definition layer has a refractive index less than that of the second sub-pixel definition layer; the first opening has a first sidewall facing a light-out side of the display substrate, the first sidewall includes a first sub-sidewall and a second sub-sidewall, the first sub-sidewall is disposed close to the anode layer, and the second sub-sidewall is located on a side of the first sub-sidewall away from the anode layer; the reflective layer covers the first sub-sidewall, and the second sub-pixel definition layer covers a side of the second sub-sidewall and the reflective layer away from the first sub-sidewall.

[0011] Optionally, the reflective layer includes a reflective surface facing the light-out side of the display substrate; the display substrate further includes a transparent protective layer covering the reflective surface, and the second sub-pixel definition layer covers a side of the second sub-sidewall and the transparent protective layer away from the reflective layer.

[0012] The material of the reflective layer includes a metal material, and the material of the transparent protective layer includes a metal oxide.

[0013] Optionally, the material of the reflective layer includes silver, and the material of the transparent protective layer includes a combination of any one or more of indium tin oxide, indium zinc oxide, and indium gallium tin oxide.

[0014] Optionally, the thickness of the reflective layer ranges from 100 angstroms to 10,000 angstroms, and the thickness of the transparent protective layer ranges from 100 angstroms to 10,000 angstroms.

[0015] Optionally, the second sub-pixel definition layer also partially covers the anode layer, and part of the anode layer is exposed in the second opening; the display substrate further includes a light-emitting functional layer located in the second opening, and the light-emitting functional layer covers the anode layer.

[0016] Optionally, the reflective layer includes a first reflective part and a second reflective part connected to each other; the first reflective part covers the first sub-sidewall, and the second reflective part covers the anode layer exposed in the first opening.

[0017] The transparent protective layer covers a side of the first reflective part away from the first sub-sidewall and a side of the second reflective part away from the anode layer; part of the transparent protective layer is exposed in the second opening; and the transparent protective layer, the reflective layer, and the anode layer are electrically connected to each other.

[0018] Optionally, the material of the transparent protective layer is the same as that of the anode layer.

[0019] Optionally, the display substrate further includes a light-emitting functional layer located in the second opening, and the light-emitting functional layer is located on a side of the transparent protective layer away from the second reflective part.

[0020] Optionally, the second opening has a second sidewall facing the light-outgoing side of the display substrate; the second sidewall is arranged in parallel with the adjacent first sidewall.

[0021] The application also provides a display device comprising the display substrate described above.

[0022] The display substrate and display device provided by the application have the following advantages. The pixel definition layer is composed of a first sub-pixel definition layer and a second sub-pixel definition layer stacked with a refractive index difference, and a total reflection interface is formed at the position of the second sub-sidewall of the first opening of the first sub-pixel definition layer; in addition, a reflective layer is arranged at the position of the first sub-sidewall of the first opening of the first sub-pixel definition layer, so that the position corresponding to the first sub-sidewall forms a mirror reflection interface; when a light-emitting functional layer is arranged in the second opening, the total reflection interface and the mirror reflection interface are distributed on the side of the light-emitting functional layer, so that part of the large-angle light rays emitted by the light-emitting functional layer to the surroundings can be totally reflected at the total reflection interface and emitted from the light-outgoing side of the display substrate, and another part of the large-angle light rays can be mirror-reflected at the mirror reflection interface and emitted from the light-outgoing side of the display substrate, so that the large-angle light rays emitted by the light-emitting functional layer to the surroundings can be effectively extracted for display, thereby significantly improving the light extraction efficiency of the device.

[0023] In addition, the application forms a mirror reflection interface with higher light extraction efficiency by arranging a reflective layer on the first sub-sidewall closer to the anode layer, so that the large-angle light rays received by the area where the first sub-sidewall is located and having an incident angle smaller than the critical angle of total reflection can be extracted efficiently through mirror reflection, thereby more effectively improving the light extraction efficiency. In addition, the application forms a total reflection interface on the second sub-sidewall away from the anode layer, so that the light rays after total reflection through the total reflection interface can be used for wide-view display, thereby avoiding excessive attenuation of wide-view brightness and affecting the overall display effect.

[0024] Therefore, the mirror reflection interface formed by the reflective layer cooperates with the total reflection interface formed by the first sub-pixel definition layer and the second sub-pixel definition layer, so that the light extraction efficiency of the device can be significantly improved while avoiding excessive attenuation of large-angle brightness, thereby ensuring the display brightness in the normal-view direction and the wide-view direction at the same time, and further improving the overall display effect of the display product. BRIEF DESCRIPTION OF DRAWINGS

[0025] The technical solutions and other advantages of the application will be apparent from the following detailed description of the specific embodiments of the application, taken in conjunction with the accompanying drawings.

[0026] Figure 1 FIG. 1 is a schematic view of a partial cross-sectional structure of an exemplary display substrate.

[0027] Figure 2 This is a partial cross-sectional structural diagram of a display substrate provided in an embodiment of this application.

[0028] Figure 3 This is a partial cross-sectional structural diagram of another display substrate provided in an embodiment of this application.

[0029] Figure 4a and Figure 4b To make Figure 3 The diagram shows a schematic of the first sub-pixel definition layer of the display substrate.

[0030] Figure 4c To make Figure 3 The diagram shows a reflective layer and a transparent protective layer of the display substrate.

[0031] Figure 4d and Figure 4e To make Figure 3 A schematic diagram of the second sub-pixel definition layer of the display substrate shown.

[0032] Figure 5 This is a cross-sectional schematic diagram of a display device provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0034] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0037] The following disclosure provides many different embodiments or examples for implementing different structures of the application. In order to simplify the disclosure of the application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the application. In addition, the application can repeatedly refer to numbers and / or letters in different examples. Such repetition is for the purpose of simplification and clarity, and in itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0038] Figure 1 An exemplary partial cross-sectional structure of a display substrate 1 is shown. As shown in Figure 1 The display substrate 1 includes an array substrate 2, an anode layer 3, a pixel definition layer 4, a light-emitting functional layer 5, an encapsulation layer 6, a touch layer 7 and a light extraction layer 8.

[0039] Specifically, the array substrate 2 includes a substrate layer 9, a thin film transistor (TFT) driving layer 10, and a planarization layer 11 stacked sequentially. An anode layer 3 is located on the planarization layer 11 and is electrically connected to the TFT driving layer 10 through a via penetrating the planarization layer 11. A pixel definition layer 4 covers at least the planarization layer 11 and has pixel openings exposing the anode layer 3. A light-emitting functional layer 5 is located on the anode layer 3 exposed in the first opening. An encapsulation layer 6 covers the pixel definition layer 4 and the light-emitting functional layer 5, and the encapsulation layer 6 can be a thin film encapsulation (TFE) structure. A touch layer 7 is located on the encapsulation layer 6 and can be fabricated using DOT (Direct on-cell touch, touchscreen directly embedded in the display screen) technology. A light extraction layer 8 is located on the touch layer 7 and is used to improve light extraction efficiency.

[0040] Specifically, an MLA structure is formed in the light extraction layer 8; the light extraction layer 8 includes a low-refractive-index layer 12 and a high-refractive-index layer 13 sequentially located on the touch layer 7; wherein, the refractive index of the low-refractive-index layer 12 is less than the refractive index of the high-refractive-index layer 13. The low-refractive-index layer 12 includes a plurality of microlenses 14 arranged in an array on the encapsulation layer 6, and the gap between any two adjacent microlenses 14 is aligned with the pixel opening. The high-refractive-index layer 13 completely covers the plurality of microlenses 14 and fills the gap between any two adjacent microlenses 14, thus serving both the functions of light extraction and planarization.

[0041] Specifically, both the low-refractive-index layer 12 and the high-refractive-index layer 13 are made of light-transmitting materials. Since the refractive index of the low-refractive-index layer 12 is lower than that of the high-refractive-index layer 13, when a portion of the light emitted from the light-emitting functional layer 5 strikes the interface formed by the microlens 14 and the high-refractive-index layer 13 at a certain angle (e.g., a wide viewing angle), total internal reflection will occur. Figure 1 As shown in optical path a; another portion of the light emitted by the light-emitting functional layer 5 (e.g., positive angle light) can pass directly through the high refractive layer 13, such as... Figure 1 As shown in optical path b; a portion of the light emitted from the light-emitting functional layer 5 enters the microlens 14, and after its refraction angle is adjusted at the interface formed by the microlens 14 and the high-refractive-index layer 13, it is transmitted (not shown in the figure). Therefore, Figure 1 The light extraction layer 8 in the display substrate 1 shown can act as a light convergence layer, which helps to improve the light extraction efficiency.

[0042] Specifically, for the flexible display substrate 1, the materials of the low-refractive layer 12 and the high-refractive layer 13 can both be organic materials; for the rigid display substrate 1, the materials of the low-refractive layer 12 and the high-refractive layer 13 can also be inorganic materials.

[0043] AlthoughFigure 1 The light extraction layer 8 in the display substrate 1 shown can improve the light extraction efficiency, but there are some drawbacks to placing the light extraction layer 8 on the touch layer 7, as described below.

[0044] On the one hand, since the light extraction layer 8 is set on the touch layer 7, the total internal reflection interface formed by the low refractive layer 12 and the high refractive layer 13 in the light extraction layer 8 is located obliquely above the light-emitting functional layer 5. Therefore, the light extraction layer 8 can only converge light rays in a small range with a wide viewing angle. For example, the light emitted from the side of the light-emitting functional layer 5 cannot illuminate the total internal reflection interface formed by the low refractive layer 12 and the high refractive layer 13. Therefore, this part of the light cannot be extracted, resulting in a severe limitation on the light extraction efficiency of the light extraction layer 8.

[0045] On the other hand, placing the light extraction layer 8 on the touch layer 7 is equivalent to adding a film layer structure on the basis of the existing display substrate 1, which will lead to an increase in the overall thickness of the display substrate 1. Figure 1 When the display substrate 1 shown is used in an OLED screen, it increases the screen thickness, thus limiting the screen's form factor design. For example, Figure 1 The display substrate 1 shown can only be applied to static curved screens with a small CG angle. For newer products such as dynamic curved screens, waterfall screens, and quad-curved screens, the addition of film layer structures will lead to a higher risk of peeling and cracking at the film layer interface.

[0046] On the other hand, when Figure 1 When the display substrate 1 shown is used in a flexible OLED screen, the materials of the low refractive layer 12 and the high refractive layer 13 in the light extraction layer 8 are both organic materials. Since the light extraction layer 8 is made after the electroluminescence (EL) material process, in order to avoid affecting the EL layer, the light extraction layer 8 can only be made using a low-temperature curing process. This results in the development of high refractive index organic materials and low refractive index organic materials being difficult, having poor stability, and being costly.

[0047] To address the above technical problems, this application provides a display substrate and a display device. By improving the structure of the pixel definition layer inside the display substrate, a microlens array is formed inside the pixel definition layer, and a reflective layer is provided in the pixel definition layer. Through the cooperation of the microlens array and the reflective layer, the light extraction efficiency can be significantly improved without increasing the thickness of the display substrate, or increasing the difficulty, stability, and cost of material development. Please refer to the following description of the embodiments for details.

[0048] like Figure 2As shown, this application embodiment provides a display substrate 20, which includes an array substrate 21, an anode layer 22, a pixel definition layer 23, a reflective layer 17, and a light-emitting functional layer 24.

[0049] Specifically, the anode layer 22 is located on the array substrate 21; the pixel definition layer 23 is located on the array substrate 21 and partially covers the anode layer 22; the pixel definition layer 23 includes a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b stacked sequentially; the first sub-pixel definition layer 23a includes a first opening 26, and the anode layer 22 is at least partially exposed in the first opening 26; the second sub-pixel definition layer 23b extends into the first opening 26 and includes a second opening 27 aligned with the first opening 26; the reflective layer 17 is located within the first opening 26.

[0050] The refractive index of the first sub-pixel defining layer 23a is less than that of the second sub-pixel defining layer 23b. The first opening 26 has a first sidewall 28 facing the light-emitting side of the display substrate 20. The first sidewall 28 includes a first sub-sidewall 28a and a second sub-sidewall 28b that are connected to each other. The first sub-sidewall 28a is disposed close to the anode layer 22, and the second sub-sidewall 28b is located on the side of the first sub-sidewall 28a away from the anode layer 22. The reflective layer 17 covers the first sub-sidewall 28a, and the second sub-pixel defining layer 23b covers the second sub-sidewall 28b and the reflective layer 17 on the side away from the first sub-sidewall 28a.

[0051] In embodiments of this application, the reflective layer 17 is located only on the first sub-sidewall 28a, the second opening 27 exposes a portion of the anode layer 22, and the second opening 27 is used to accommodate the light-emitting functional layer 24. It can be understood that the second opening 27 is equivalent to a pixel opening.

[0052] Specifically, the second sub-pixel definition layer 23b also partially covers the anode layer 22, and part of the anode layer 22 is exposed in the second opening 27; the light-emitting functional layer 24 is located in the second opening 27 and covers the anode layer 22 to achieve electrical connection with the anode layer 22.

[0053] Specifically, the reflective layer 17 includes a reflective surface 18 facing the light-emitting side of the display substrate 20.

[0054] When the wide-viewing-angle light emitted from the light-emitting functional layer 24 shines on the reflective surface 18 of the reflective layer 17, it undergoes specular reflection and is emitted from the light-emitting side of the display substrate 20, such as... Figure 2 As shown in optical path c, when the wide-viewing-angle light emitted from the light-emitting functional layer 24 shines on the surface of the second sub-sidewall 28b, it undergoes total internal reflection and exits from the light-emitting side of the display substrate 20, as shown in Figure c. Figure 2 The light path d shown is illustrated. The light emitted from the light-emitting functional layer 24 at a positive viewing angle passes directly through the overlying film layers (e.g., the encapsulation layer and the touch layer), as shown...Figure 2 The optical path e is shown in the diagram.

[0055] In one specific embodiment, the angle between at least a portion of the light reflected from the reflective surface 18 and the thickness direction (or frontal viewing direction) of the display substrate 20 is smaller than the angle between the light reflected from the surface of the second sub-sidewall 28b and the thickness direction of the display substrate 20.

[0056] Understandably, the light reflected from the reflective surface 18 is closer to the normal viewing angle direction; the light emitted from the surface of the second sub-sidewall 28b after total internal reflection is relatively deviated from the normal viewing angle direction. This part of the light can be used to maintain the brightness of the wide viewing angle at a normal level to ensure the wide viewing angle display effect.

[0057] In the embodiments of this application, the pixel definition layer 23 is composed of a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b stacked together, having a refractive index difference. A total internal reflection interface is formed at the position of the second sub-sidewall 28b of the first opening 26 of the first sub-pixel definition layer 23a. Furthermore, a reflective layer 17 is provided at the position of the first sub-sidewall 28a of the first opening 26 of the first sub-pixel definition layer 23a, so that a specular reflection interface is formed at the position corresponding to the first sub-sidewall 28a. Since the light-emitting functional layer 24 is located inside the second opening 27, the total internal reflection interface and the specular reflection interface formed on the first sidewall 28 are distributed on the side of the light-emitting functional layer 24 or even its entire periphery. A portion of the wide-viewing-angle light emitted by the light-emitting functional layer 24 can undergo total internal reflection at the total internal reflection interface and be emitted from the light-emitting side of the display substrate 20. Another portion of the wide-viewing-angle light can undergo specular reflection at the specular reflection interface and be emitted from the light-emitting side of the display substrate 20. This allows the wide-viewing-angle light emitted by the light-emitting functional layer 24 to be effectively extracted for display, thereby significantly improving the light extraction efficiency of the device.

[0058] Understandably, the light emitted from the side of the light-emitting functional layer 24 near the pixel definition layer 23, which would otherwise be lost by the optical waveguide, as well as the light scattered and absorbed at large angles, can be extracted through the total internal reflection interface formed by the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b and the specular reflection interface formed by the reflective layer 17. Therefore, the light extraction efficiency of the device is greatly improved.

[0059] It should be noted that the device described in this application refers to a light-emitting device composed of a light-emitting functional layer 24.

[0060] Typically, the angle of incidence of light illuminating the area of ​​the first sub-sidewall 28a from the same position on the side of the light-emitting functional layer 24 is relatively small, while the angle of incidence of light illuminating the area of ​​the second sub-sidewall 28b is relatively large. If total internal reflection interfaces are formed at both the first sub-sidewall 28a and the second sub-sidewall 28b, then when the angle of incidence of light incident on the first sub-sidewall 28a does not reach the critical angle of total internal reflection, this portion of light cannot be effectively extracted, thus affecting the light extraction efficiency. If specular reflection interfaces are formed at both the first sub-sidewall 28a and the second sub-sidewall 28b, the light extraction effect of specular reflection is too high, causing the extracted light to be emitted close to the normal viewing angle direction, resulting in excessive attenuation of wide-viewing-angle brightness and affecting the wide-viewing-angle display, thereby affecting the overall display effect.

[0061] In the embodiments of this application, since the first sub-sidewall 28a is located closer to the anode layer 22 than the second sub-sidewall 28b, the specular reflection interface formed by the reflective layer 17 is located closer to the light-emitting functional layer 24 than the total internal reflection interface formed by the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b. Furthermore, since there is no requirement for the angle of incidence when light undergoes specular reflection at the specular reflection interface, while a greater than the critical angle is required for total internal reflection at the total internal reflection interface, the light extraction efficiency at the specular reflection interface is higher than that at the total internal reflection interface. Therefore, by placing the specular reflection interface, which has higher light extraction efficiency, closer to the anode layer 22, the embodiments of this application can extract wide-angle light even if the angle of incidence does not meet the total internal reflection condition, thereby significantly improving the light extraction efficiency of the device. Conversely, by placing the total internal reflection interface, which has lower light extraction efficiency, further away from the anode layer 22, it can ensure that the light after total internal reflection falls within a wide viewing angle range and can be used for wide-view display, avoiding excessive brightness attenuation at wide viewing angles and affecting the overall display effect.

[0062] In other words, compared with forming a total reflection interface by covering the second sub-pixel definition layer 23b on both the first sub-sidewall 28a and the second sub-sidewall 28b, the embodiments of this application can significantly improve the light extraction efficiency of the device; compared with forming a specular reflection interface on both the first sub-sidewall and the second sub-sidewall, this application can improve the light extraction efficiency while avoiding excessive attenuation of the brightness of the display substrate 20 at a wide viewing angle, thus affecting the overall display effect.

[0063] Therefore, the embodiments of this application, through the cooperation of the mirror reflection interface formed by the reflective layer 17 and the total reflection interface formed by the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b, can significantly improve the light extraction efficiency of the device while avoiding excessive brightness attenuation at wide viewing angles, thereby ensuring the display brightness in both the positive viewing angle and the wide viewing angle, which is conducive to improving the overall display effect of the display product.

[0064] Specifically, the stacked first subpixel definition layer 23a and the second subpixel definition layer 23b together constitute a pixel definition layer 23 for defining the subpixel area, and the second opening 27 on the second subpixel definition layer 23b is a pixel opening.

[0065] Meanwhile, the low-refractive-index first sub-pixel defining layer 23a and the high-refractive-index second sub-pixel defining layer 23b also constitute a light extraction layer with a microlens array (MLA) structure; that is, the pixel defining layer 23 provided in this embodiment can be reused as a light extraction layer. Therefore, the pixel defining layer 23 provided in this embodiment can both define the sub-pixel area and improve the light extraction efficiency.

[0066] It should be noted that the pixel definition layer 23 provided in this embodiment is composed of a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b. This can be understood as layering the pixel definition layers in existing display products, rather than adding another pixel definition layer on top of the existing one. Therefore, the thickness of the pixel definition layer 23 provided in this embodiment can be the same as or similar to the thickness of the pixel definition layers in existing display products. Of course, in other embodiments, the overall thickness of the pixel definition layer 23 can also be adjusted according to the light emission efficiency requirements.

[0067] Furthermore, forming a reflective layer 17 in the first opening 26 between the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b will not significantly affect the thickness of the display substrate 20.

[0068] Compared to Figure 1 The light extraction layer 8 in the display substrate 1 shown in this application embodiment reuses the pixel definition layer 23, which is composed of a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b with different refractive indices, as the light extraction layer, and a reflective layer 17 is provided in the pixel definition layer 23, which has the following advantages:

[0069] On the one hand, since the first sub-pixel definition layer 23a, the second sub-pixel definition layer 23b, and the reflective layer 17 are closer to the center of the light-emitting source (i.e., the light-emitting functional layer 24), the light extraction efficiency of this application is more significant under the same Gaussian angle distribution of the optical path. On the other hand, the specular reflection interface formed by the reflective layer 17, in conjunction with the total internal reflection interface formed by the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b, can significantly improve the light extraction efficiency of the device while avoiding excessive brightness attenuation at wide viewing angles, thereby ensuring display brightness in both the positive and wide viewing angle directions, which is conducive to improving the overall display effect of the display product. On the one hand, it eliminates the need for additional new film layers, which helps reduce the overall thickness of the display substrate 20. This allows the display substrate 20 to be applied not only to large-angle waterfall screens and ultra-curved screens, but also to dynamic bending screens and other product forms, greatly improving the adaptability of product forms. On the other hand, since the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b are fabricated before the light-emitting functional layer 24, both the high-refractive-index organic materials and the low-refractive-index organic materials involved in the embodiments of this application can be processed using high-temperature processes. Therefore, the selection of high-refractive-index organic materials and low-refractive-index organic materials is wider, the cost is lower, and the performance is more stable.

[0070] Specifically, the array substrate 21 includes a substrate layer 29, a thin film transistor (TFT) driving layer 30 located on the substrate layer 29, and a planarization (PLN) layer 31 located on the TFT driving layer 30. The anode layer 22 and the pixel definition layer 23 are located on the planarization layer 31.

[0071] Specifically, the anode layer 22 includes a plurality of anode blocks 25 arranged in an array. The first sub-pixel definition layer 23a has a plurality of first openings 26 that are aligned one-to-one with the plurality of anode blocks 25, and at least a portion of each anode block 25 is exposed in the corresponding first opening 26. Each anode block 25 is electrically connected to the thin-film transistor driving layer 30 through a via through the planarization layer 31.

[0072] Specifically, the material of the substrate 29 includes, but is not limited to, polyimide (PI). For the flexible display substrate 20, the material of the substrate 29 is preferably an organic material.

[0073] Specifically, the material of the anode layer 22 includes any one or a combination of indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium tin oxide (IGZO).

[0074] Specifically, the thickness of the anode layer 22 ranges from 100 angstroms (Å) to 10,000 angstroms, for example, the thickness of the anode layer 22 is 100 Å, 200 Å, 300 Å, 500 Å, 800 Å, 1000 Å, 5000 Å or 10000 Å.

[0075] Specifically, the first sub-pixel definition layer 23a also includes a bottom 32 facing the array substrate 21. The included angle formed between the first sidewall 28 and the bottom 32 of the first sub-pixel definition layer 23a is the taper angle of the first sub-pixel definition layer 23a. The taper angle ranges from 30° to 70°. For example, the taper angle of the first sub-pixel definition layer 23a is 30°, 40°, 50°, 60° or 70°.

[0076] It should be noted that if the taper angle of the first sub-pixel definition layer 23a is too high or too low, there will be viewing angle problems, so it needs to be controlled within this range.

[0077] Specifically, in the positive viewing direction of the display substrate 20, the shape of the cross-section of the first sidewall 28 can be a straight line or an arc surface. This application does not limit this, as long as it can meet the requirements of the taper angle and achieve the light extraction effect.

[0078] Specifically, the first sub-pixel definition layer 23a can cover only the upper surface of the planarization layer 31 and the sidewall of the anode block 25, that is, the first opening 26 exposes the entire upper surface of the anode block 25 (i.e. the surface away from the planarization layer 31); of course, the first sub-pixel definition layer 23a can also cover the edge of the upper surface of the anode block 25, in which case the first opening 26 exposes a part of the upper surface of the anode block 25.

[0079] Specifically, the reflective layer 17 may extend to connect with the anode layer 22, or it may be spaced apart from the anode layer 22. Alternatively, a spacer may be provided between the reflective layer 17 and the anode layer 22. This application does not limit the scope of the application.

[0080] Specifically, the display substrate 20 also includes a transparent protective layer 19 covering the reflective surface 18 of the reflective layer 17, and a second sub-pixel definition layer 23b covering the second sub-sidewall 28b and the transparent protective layer 19 on the side away from the reflective layer 17.

[0081] Specifically, the reflective layer 17 is made of metallic materials, and the transparent protective layer 19 is made of metal oxides.

[0082] It should be noted that the transparent protective layer 19 is provided to prevent the reflective layer 17 of the metal material from being damaged by the etching solution during the patterning process of the upper film layer, thereby protecting the reflective layer 17.

[0083] In one specific embodiment, the material of the reflective layer 17 includes metallic silver (Ag), and the material of the transparent protective layer 19 includes any one or a combination of indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium tin oxide (IGZO).

[0084] It is understandable that the material of the transparent protective layer 19 can be the same as that of the anode layer 22, but is not limited to this.

[0085] Specifically, the thickness of the reflective layer 17 ranges from 100 Å to 10000 Å. For example, the thickness of the reflective layer 17 is 100 Å, 200 Å, 300 Å, 500 Å, 800 Å, 1000 Å, 5000 Å, or 10000 Å.

[0086] Specifically, the thickness of the transparent protective layer 19 ranges from 100A to 10000A. For example, the thickness of the transparent protective layer 19 is 100A, 200A, 300A, 500A, 800A, 1000A, 5000A, or 10000A.

[0087] Specifically, the second opening 27 of the second sub-pixel definition layer 23b has a second sidewall 33 facing the light-emitting side of the display substrate 20; the second sidewall 33 is located above the adjacent first sidewall 28.

[0088] In one specific embodiment, the second sidewall 33 is arranged parallel to the adjacent first sidewall 28. That is, the taper angle of the second sub-pixel definition layer 23b is the same as the taper angle of the first sub-pixel definition layer 23a.

[0089] It should be noted that when the taper angle of the first sub-pixel definition layer 23a is not the same as that of the second sub-pixel definition layer 23b, the combination of the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b still has a light extraction effect; however, when the taper angle of the first sub-pixel definition layer 23a is equal to the taper angle of the second sub-pixel definition layer 23b, the light extraction effect will be better.

[0090] Specifically, the size of the second opening 27 is smaller than the size of the first opening, so that the second sub-pixel definition layer 23b can cover the second sub-sidewall 28b of the first sub-pixel definition layer 23a and the transparent protective layer 19.

[0091] Specifically, the thickness of the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b can be determined based on the overall light effect of the display substrate 20, and is not limited here.

[0092] Specifically, the refractive index of the first sub-pixel defining layer 23a ranges from 1.3 to 1.6, the refractive index of the second sub-pixel defining layer 23b ranges from 1.4 to 1.7, and the refractive index of the first sub-pixel defining layer 23a is less than the refractive index of the second sub-pixel defining layer 23b.

[0093] Specifically, in the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b, at least the material of the first sub-pixel definition layer 23a is an organic material.

[0094] In one specific embodiment, the materials of the first sub-pixel defining layer 23a and the second sub-pixel defining layer 23b are organic photoresist materials with different refractive indices; the organic photoresist materials include any one or more combinations of polyimide resin, epoxy resin, acrylic resin and siloxane resin.

[0095] In another specific embodiment, the first sub-pixel defining layer 23a is made of an organic photoresist material, and the second sub-pixel defining layer 23b is made of an inorganic transparent material. The organic photoresist material includes any one or more combinations of polyimide resin, epoxy resin, acrylic resin, and siloxane resin, while the inorganic transparent material includes one or more combinations of silicon nitride, silicon oxide, and silicon oxynitride. In this case, the specific fabrication method can be adjusted accordingly based on the change in the material of the second sub-pixel defining layer 23b.

[0096] Specifically, the light-emitting functional layer 24 is located in the second opening 27 and may also cover the second sidewall 33. The light-emitting functional layer 24 includes a light-emitting layer (not shown in the figure) and a cathode layer (not shown in the figure) located on the side of the light-emitting layer away from the anode layer 22. It is understood that the material of the light-emitting layer includes organic light-emitting materials. In this case, the anode layer 22, the light-emitting layer, and the cathode layer constitute an OLED device.

[0097] Specifically, the light-emitting layer and the cathode layer can be prepared using a vapor deposition process, but are not limited to this.

[0098] Of course, in other embodiments, the material of the light-emitting layer can also be other types of materials, which are not limited here.

[0099] Specifically, the display substrate 20 also includes an encapsulation layer 36 covering the second sub-pixel definition layer 23b and the light-emitting functional layer 24, and a touch layer 37 located on the encapsulation layer 36.

[0100] Specifically, the encapsulation layer 36 can be a thin-film encapsulation (TFE) structure, specifically including a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked sequentially on the second sub-pixel definition layer 23b and the light-emitting functional layer 24; wherein, the first inorganic encapsulation layer covers the second sub-pixel definition layer 23b and the light-emitting functional layer 24, and the refractive index of the first inorganic encapsulation layer is less than the refractive index of the second sub-pixel definition layer 23b, which is beneficial to further improve the light extraction efficiency.

[0101] It should be noted that after the light path exits from the second sub-pixel definition layer 23b, it passes through the encapsulation layer 36. Therefore, the interface between the second sub-pixel definition layer 23b and the encapsulation layer 36 affects the total internal reflection. However, the film layer interface of a conventional display substrate 20 without an MLA structure inherently has a total internal reflection loss. In this embodiment, the total internal reflection loss is reduced due to the difference in refractive index between the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b. Therefore, the influence of the interface between the second sub-pixel definition layer 23b and the encapsulation layer 36 on the total internal reflection can be disregarded.

[0102] Specifically, the touch layer 37 can be formed using DOT technology, but is not limited to this.

[0103] The display substrate 20 provided in this application embodiment has the following advantages.

[0104] On one hand, the pixel definition layer 23 is composed of a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b stacked together, with a total internal reflection interface formed at the position of the second sub-sidewall 28b of the first opening 26 of the first sub-pixel definition layer 23a; on the other hand, a reflective layer 17 is provided at the position of the first sub-sidewall 28a of the first opening 26 of the first sub-pixel definition layer 23a, so that a specular reflection interface is formed at the position corresponding to the first sub-sidewall 28a; when the light-emitting functional layer 24 is provided in the second opening 27, the total internal reflection interface and the specular reflection interface are distributed on the side of the light-emitting functional layer 24 or even the entire periphery. Therefore, a portion of the wide-viewing-angle light emitted by the light-emitting functional layer 24 can undergo total internal reflection at the total internal reflection interface and be emitted from the light-emitting side of the display substrate 20, while another portion of the wide-viewing-angle light can undergo specular reflection at the specular reflection interface and be emitted from the light-emitting side of the display substrate 20. This allows the wide-viewing-angle light emitted by the light-emitting functional layer 24 to be effectively extracted for display, thereby significantly improving the light extraction efficiency of the device.

[0105] On the other hand, by setting a reflective layer 17 on the first sub-sidewall 28a closer to the anode layer 22, a mirror reflection interface with higher light extraction efficiency is formed. The large-angle light rays received in the area where the first sub-sidewall 28a is located can be efficiently extracted through mirror reflection, which is less than the critical angle of total internal reflection, thereby improving the light extraction efficiency more effectively.

[0106] On the other hand, by forming a total reflection interface on the second sub-sidewall 28b away from the anode layer 22, the light after total reflection through the total reflection interface can be used for wide-viewing-angle display, avoiding excessive brightness attenuation in the wide-viewing-angle display and affecting the overall display effect.

[0107] On the other hand, the pixel definition layer 23 is composed of a first sub-pixel definition layer 23a and a second sub-pixel definition layer 23b with a refractive index difference. It can be reused as a light extraction layer with an MLA structure without the need to add a new film layer structure as a light extraction layer. The reflective layer 17 is disposed between the first sub-sidewall 28a of the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b, which helps to reduce the overall thickness of the display substrate 20. This allows the display substrate 20 to be applied not only to large-angle waterfall screens and ultra-curved screens, but also to dynamic bending screens and other product forms, which greatly improves the product form adaptability.

[0108] On the other hand, the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b are fabricated before the light-emitting functional layer 24. Both the high-refractive-index organic materials and the low-refractive-index organic materials involved can be fabricated using high-temperature processes. Therefore, the selection of high-refractive-index organic materials and low-refractive-index organic materials is wider, the cost is lower, and the performance is more stable.

[0109] Therefore, the embodiments of this application, through the cooperation of the mirror reflection interface formed by the reflection layer 17 and the total reflection interface formed by the first sub-pixel definition layer 23a and the second sub-pixel definition layer 23b, can significantly improve the light extraction efficiency of the device, ensure that the brightness at a wide viewing angle is within the normal range, improve the adaptability of product form, reduce material costs, and improve the stability of materials.

[0110] like Figure 3 As shown, embodiments of this application also provide another display substrate 20', which differs from the aforementioned embodiments in that the reflective layer 17 includes a first reflective portion 17a and a second reflective portion 17b interconnected; the first reflective portion 17a covers the first sub-sidewall 28a, and the second reflective portion 17b covers the anode layer 22 exposed in the first opening 26; a transparent protective layer 19 covers the side of the first reflective portion 17a away from the first sub-sidewall 28a, and covers the side of the second reflective portion 17b away from the anode layer 22; a portion of the transparent protective layer 19 is exposed in the second opening 27; the transparent protective layer 19, the reflective layer 17, and the anode layer 22 are electrically connected to each other.

[0111] It is understood that in the embodiments of this application, the reflective layer 17 is not only disposed on the first sub-sidewall 28a, but also on the anode layer 22 exposed in the first opening 26. In order to ensure good electrical connection performance between the light-emitting functional layer 24 and the anode layer 22, both the reflective layer 17 and the transparent protective layer 19 are conductors.

[0112] Specifically, the material of the transparent protective layer 19 and the anode layer 22 can be the same, both being transparent electrode materials, but are not limited to this.

[0113] Specifically, the light-emitting functional layer 24 is located in the second opening 27 and on the side of the transparent protective layer 19 away from the second reflective portion 17b. That is, the light-emitting functional layer 24 covers the transparent protective layer 19 exposed in the second opening 27 and achieves electrical connection with the anode layer 22 through the reflective layer 17 and the transparent protective layer 19.

[0114] The embodiments of this application have the same technical effects as the foregoing embodiments, and will not be repeated here.

[0115] like Figure 3 , Figures 4a to 4e As shown, embodiments of this application also provide a process for fabricating a display substrate 20', including the following steps:

[0116] like Figure 4a As shown, a first organic photoresist material layer 34 having a first refractive index is coated on an array substrate 21 on which an anode layer 22 is formed, so that the first organic photoresist material layer 34 covers the anode layer 22 and the planarization layer 31; wherein, the anode layer 22 includes a plurality of anode blocks 25;

[0117] like Figure 4b As shown, the first organic photoresist material layer 34 is patterned using an exposure and development process to form a first sub-pixel definition layer 23a with a first opening 26; wherein the first opening 26 is aligned with the anode block 25, and at least a portion of the anode block 25 is exposed in the first opening 26.

[0118] like Figure 4c As shown, a reflective layer 17 and a transparent protective layer 19 are formed in the first opening 26; the reflective layer 17 and the transparent protective layer 19 cover the anode block 25 exposed in the first opening 26 and extend to the first sub-sidewall 28a covering the first opening 26.

[0119] like Figure 4d As shown, a second organic photoresist layer 35 with a second refractive index is coated and covers the first sub-pixel definition layer 23a and the transparent protective layer 19; wherein the second refractive index is greater than the first refractive index;

[0120] like Figure 4eAs shown, the second organic photoresist layer 35 is patterned using an exposure and development process to form a second sub-pixel definition layer 23b with a second opening 27; wherein the second opening 27 is aligned with the first opening 26, and the size OP2 of the second opening 27 is smaller than the size OP1 of the first opening 26, and a portion of the transparent protective layer 19 is exposed in the second opening 27; and

[0121] like Figure 3 As shown, a light-emitting functional layer 24 is formed in the second opening 27, and an encapsulation layer 36 and a touch layer 37 are formed in sequence, covering the pixel definition layer 23 and the light-emitting functional layer 24.

[0122] Specifically, such as Figure 4b As shown, the size of the first opening 26 is OP1, which can be defined as the opening diameter of the first opening 26 on the side near the anode block 25, which is equivalent to the lateral width of the anode block 25 exposed in the first opening 26; the included angle θ1 between the first sidewall 28 and the bottom 32 is the taper angle of the first sub-pixel definition layer 23a.

[0123] Specifically, such as Figure 4e As shown, the size of the second opening 27 is OP2, which can be defined as the opening diameter of the second opening 27 on the side near the anode block 25, which is equivalent to the lateral width of the anode block 25 exposed in the second opening 27; the included angle θ2 between the second sidewall 33 and the upper surface of the transparent protective layer 19 is the taper angle of the second sub-pixel definition layer 23b.

[0124] It should be noted that the bottom 32 of the first sub-pixel definition layer 23a is arranged parallel to the upper surface of the anode layer 22. Therefore, in the accompanying drawings of this application, θ1 is marked between the first sidewall 28 of the first sub-pixel definition layer 23a and the upper surface of the anode layer 22.

[0125] like Figure 5 As shown, this application embodiment also provides a display device 38, which includes the display substrate 20 or display substrate 20' described in the foregoing embodiment; the display device 38 also includes a protective cover plate 39 located on the light-emitting side of the display substrate 20 or display substrate 20'; the material of the protective cover plate 39 includes ultra-thin glass, but is not limited thereto.

[0126] Specifically, the product form of display device 38 includes, but is not limited to, any one of static curved screen, dynamic curved screen, waterfall screen and four-curved screen.

[0127] Of course, in other embodiments, the display substrate 20 or display substrate 20' provided in this application embodiment can also be used in a backlight device, but is not limited thereto.

[0128] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0129] The above provides a detailed description of a display substrate and display device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A display substrate, characterized by, The display device comprises: an array substrate; an anode layer located on the array substrate; a pixel definition layer located on the array substrate and comprising a first sub-pixel definition layer and a second sub-pixel definition layer arranged in sequence; the first sub-pixel definition layer comprises a first opening, and the anode layer is at least partially exposed in the first opening; the second sub-pixel definition layer extends into the first opening and comprises a second opening arranged in alignment with the first opening; and a reflective layer located in the first opening; and a light-emitting functional layer located in the second opening; wherein the refractive index of the first sub-pixel definition layer is less than the refractive index of the second sub-pixel definition layer; the first opening has a first sidewall facing the light-emitting side of the display substrate, the first sidewall comprises a first sub-sidewall and a second sub-sidewall, the first sub-sidewall is arranged close to the anode layer, and the second sub-sidewall is located on the side of the first sub-sidewall away from the anode layer; the reflective layer covers the first sub-sidewall and is connected with the anode layer, and the second sub-pixel definition layer covers the second sub-sidewall and the side of the reflective layer away from the first sub-sidewall; of the light emitted by the light-emitting functional layer, part of the light is incident on the reflective layer and is reflected by the reflective layer to be emitted from the light-emitting side of the display substrate, and part of the light is incident on the second sub-sidewall and is reflected by the second sub-sidewall to be emitted from the light-emitting side of the display substrate. The reflective layer comprises a reflective surface facing the light-emitting side of the display substrate; the display substrate further comprises a transparent protective layer covering the reflective surface, and the second sub-pixel definition layer covers the second sub-sidewall and the side of the transparent protective layer away from the reflective layer; the material of the reflective layer comprises a metal material, and the material of the transparent protective layer comprises a metal oxide.

2. The display substrate of claim 1, wherein, The material of the reflective layer comprises silver, and the material of the transparent protective layer comprises a combination of any one or more of indium tin oxide, indium zinc oxide, and indium gallium tin oxide. The thickness of the reflective layer ranges from 100 angstroms to 10,000 angstroms, and the thickness of the transparent protective layer ranges from 100 angstroms to 10,000 angstroms. 3.The display substrate of claim 2, wherein, The second sub-pixel definition layer also partially covers the anode layer, and part of the anode layer is exposed in the second opening; the light-emitting functional layer covers the anode layer.

4. The display substrate of claim 2, wherein, The reflective layer comprises a first reflective portion and a second reflective portion connected to each other; the first reflective portion covers the first sub-sidewall, and the second reflective portion covers the anode layer exposed in the first opening; 5. The display substrate according to any one of claims 2 to 4, characterized in that, the transparent protective layer covers the side of the first reflective portion away from the first sub-sidewall and the side of the second reflective portion away from the anode layer; part of the transparent protective layer is exposed in the second opening; the transparent protective layer, the reflective layer, and the anode layer are electrically connected to each other. 6.The display substrate according to any one of claims 2 to 4, characterized in that, The material of the transparent protective layer is the same as the material of the anode layer. The light-emitting functional layer is located on the side of the transparent protective layer away from the second reflective portion. 7.The display substrate of claim 6, wherein, ​ 8.The display substrate of claim 6, wherein, ​ 9.The display substrate of claim 1, wherein, The second opening has a second sidewall facing a light-outgoing side of the display substrate; the second sidewall is arranged in parallel with the adjacent first sidewall.

10. A display device, characterized by comprising: The display substrate comprises any one of claims 1 to 9.

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