Display panel and display apparatus

Abstract

Provided in the present application are a display panel and a display apparatus. The display panel comprises a substrate, a light-emitting device layer and a cover layer, the cover layer comprising at least one first cover layer and at least one second cover layer, wherein the refractive index of the first cover layer is different from that of the second cover layer; and by making the phase-transition temperature of the first cover layer less than the phase-transition temperature of the second cover layer, the light-emitting effect of the cover layer can be improved, thereby improving the light-emitting efficiency and stability of the display panel.

Description

Display panel and display device

[0001] This application claims priority to Chinese patent application No. 202411614761.6, filed on November 12, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of display technology, and more particularly to a display panel and display device. Background Technology

[0003] Organic light-emitting diodes (OLEDs) are organic electroluminescent devices that emit light through the injection and recombination of charge carriers. Due to their advantages such as thinness, high brightness, low power consumption, fast response, high luminous efficiency, and good flexibility, they can meet consumers' new demands for display forms. As a result, more and more panel manufacturers around the world are investing heavily in research and development, which has greatly promoted the industrialization of OLED display panels. Invention Overview

[0004] With the continuous development of display technology, the requirements for power consumption and stability of display panels are becoming increasingly stringent. Currently, a capping layer is typically placed on the cathode of an organic light-emitting diode (OLED). The microcavity structure of the capping layer effectively extracts light generated from the light-emitting layer of the OLED, thereby improving the light extraction efficiency of the OLED. However, due to the short crystallization time of the capping layer, the resulting grains are relatively large, leading to an uneven interface between the capping layer and the metal cathode. This alters the microcavity structure within the capping layer, resulting in a decrease in the light extraction efficiency and stability of the OLED.

[0005] Therefore, it is necessary to provide a display panel and display device to improve this deficiency.

[0006] In a first aspect, embodiments of this application provide a display panel, including:

[0007] substrate;

[0008] A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together;

[0009] A cover layer is disposed on the surface of the cathode away from the light-emitting layer;

[0010] The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer closest to the cathode that is away from the cathode. The refractive index of the first capping layer is less than that of the second capping layer, and the phase transition temperature of the first capping layer is less than that of the second capping layer.

[0011] Secondly, embodiments of this application also provide a display device, the display device including a display panel, the display panel including:

[0012] substrate;

[0013] A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together;

[0014] A cover layer is disposed on the surface of the cathode away from the light-emitting layer;

[0015] The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer closest to the cathode that is away from the cathode. The refractive index of the first capping layer is less than that of the second capping layer, and the phase transition temperature of the first capping layer is less than that of the second capping layer. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments disclosed. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 is a schematic diagram of the film layer structure of the display panel provided in an embodiment of this application;

[0018] Figure 2 is a schematic diagram of the optical path in the display panel provided in an embodiment of this application;

[0019] Figure 3 is a schematic diagram of the structure of the display device provided in an embodiment of this application.

[0020] Explanation of reference numerals in the attached figures:

[0021] 1. Substrate;

[0022] 2. Light-emitting device layer; 21. Anode; 22. Light-emitting layer; 221. Hole layer; 222. Organic light-emitting material layer; 223. Electron layer; 23. Cathode;

[0023] 3. Covering layer; 31. First covering layer; 32. Second covering layer;

[0024] 4. Inorganic capping layer;

[0025] 5. Encapsulation layer; 51. First inorganic encapsulation layer; 52. Organic encapsulation layer; 53. Second inorganic encapsulation layer;

[0026] 1000, Display device; 100, Display panel; 200, Housing. Embodiments of the present invention

[0027] 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.

[0028] In the description of this application, it should be understood that the terms "upper," "lower," etc., indicating the orientation or positional relationship based on the orientation or positional relationship 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.

[0029] Reference numerals and / or reference letters may be repeated in different embodiments of this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate the relationship between the various implementations and / or settings discussed.

[0030] This application provides a display panel and display device that can improve the light extraction efficiency and stability of organic light-emitting diodes in the display panel.

[0031] To achieve the above objectives, embodiments of this application provide a display panel, including:

[0032] substrate;

[0033] A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together;

[0034] A cover layer is disposed on the surface of the cathode away from the light-emitting layer;

[0035] The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer closest to the cathode that is away from the cathode. The refractive index of the first capping layer is less than that of the second capping layer, and the phase transition temperature of the first capping layer is less than that of the second capping layer.

[0036] Optionally, the first cover layer has a first glass transition temperature, the second cover layer has a second glass transition temperature, and the first glass transition temperature is lower than the second glass transition temperature.

[0037] Optionally, the difference between the second glass transition temperature and the first glass transition temperature is greater than or equal to 30 degrees Celsius and less than or equal to 40 degrees Celsius.

[0038] Optionally, the first covering layer has a first melting temperature, the second covering layer has a second melting temperature, and the first melting temperature is lower than the second melting temperature.

[0039] Optionally, the difference between the second melting temperature and the first melting temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius.

[0040] Optionally, the first capping layer has a first sublimation temperature, the second capping layer has a second sublimation temperature, and the first sublimation temperature is lower than the second sublimation temperature.

[0041] Optionally, the difference between the second sublimation temperature and the first sublimation temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius.

[0042] Optionally, the covering layer includes at least two stacked first covering layers, with the second covering layer disposed between two adjacent first covering layers.

[0043] Optionally, the refractive index of the first covering layer is greater than or equal to 1.4 and less than or equal to 1.6, and the refractive index of the second covering layer is greater than or equal to 1.8 and less than or equal to 2.1.

[0044] Optionally, the thickness of the first covering layer is less than the thickness of the second covering layer.

[0045] Optionally, the thickness of the first cover layer is greater than or equal to 12 nanometers and less than or equal to 18 nanometers, and the thickness of the second cover layer is greater than or equal to 45 nanometers and less than or equal to 70 nanometers.

[0046] Optionally, the display panel further includes an inorganic cover layer, which is disposed on the surface of the first cover layer furthest from the cathode.

[0047] The inorganic coating material includes alkali metal halides.

[0048] Optionally, the refractive index of the inorganic coating layer is less than that of the first coating layer.

[0049] Optionally, the refractive index of the inorganic coating layer is greater than or equal to 1.2 and less than or equal to 1.4.

[0050] Optionally, the capping layer includes two first capping layers and one second capping layer, wherein the sum of the thickness of the inorganic capping layer and the thickness of the first capping layer furthest from the cathode is greater than the thickness of the first capping layer closest to the cathode.

[0051] Optionally, the display panel further includes an encapsulation layer disposed on the surface of the inorganic cover layer away from the cover layer. The encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked on the surface of the inorganic cover layer away from the cover layer.

[0052] Optionally, the cover layer includes two first cover layers and one second cover layer, wherein the thickness of the first inorganic encapsulation layer is greater than the sum of the thicknesses of the inorganic cover layer and the second cover layer.

[0053] Embodiments of this application also provide a display device, the display device including a display panel, the display panel including:

[0054] substrate;

[0055] A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together;

[0056] A cover layer is disposed on the surface of the cathode away from the light-emitting layer;

[0057] The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer closest to the cathode that is away from the cathode. The refractive index of the first capping layer is less than that of the second capping layer, and the phase transition temperature of the first capping layer is less than that of the second capping layer.

[0058] In the display panel of this application embodiment, by making the refractive indices of the first cover layer and the second cover layer different, the weak microcavity effect outside the light-emitting device layer is enhanced, causing light to undergo multiple reflections and interferences in the microcavity structure of the light-emitting device layer and the cover layer, thereby enhancing the luminous intensity of light of a specific wavelength, reducing light loss, and thus improving the light extraction efficiency. On this basis, by making the phase transition temperature of the first cover layer lower than that of the second cover layer, when the material of the first cover layer comes into contact with the cathode surface with residual heat, the crystallization time of the first cover layer will be extended, and the grains generated in the first cover layer will be finer, making the film layer at the interface between the first cover layer and the cathode more flat and uniform. This can improve the light extraction effect of the cover layer, thereby improving the light extraction efficiency and stability of the display panel.

[0059] This application provides a display panel, which includes a substrate, a light-emitting device layer, and a cover layer. The light-emitting device layer is disposed on one side of the substrate and includes an anode, a light-emitting layer, and a cathode stacked together. The cover layer is disposed on the surface of the cathode away from the light-emitting layer. The cover layer includes at least one first cover layer and at least one second cover layer. The second cover layer is disposed on the side of the first cover layer closest to the cathode away from the cathode. The refractive indices of the first cover layer and the second cover layer are different, and the phase transition temperature of the first cover layer is lower than that of the second cover layer.

[0060] In this embodiment, by making the refractive indices of the first and second cover layers different, the weak microcavity effect outside the light-emitting device layer is enhanced. This causes light to undergo multiple reflections and interferences within the microcavity structures of the light-emitting device layer and the cover layer, thereby enhancing the luminous intensity of specific wavelengths of light, reducing light loss, and improving light extraction efficiency. Furthermore, by making the phase transition temperature of the first cover layer lower than that of the second cover layer, when the material of the first cover layer comes into contact with the cathode surface with residual heat, the crystallization time of the first cover layer is prolonged, and the grains generated in the first cover layer are finer. This makes the film layer at the interface between the first cover layer and the cathode smoother and more uniform, thus improving the light extraction effect of the cover layer and thereby improving the light extraction efficiency and stability of the display panel.

[0061] Referring to Figure 1, which is a schematic diagram of the film layer structure of a display panel provided in an embodiment of this application, the display panel 100 includes a substrate 1 and a light-emitting device layer 2, the light-emitting device layer 2 being disposed on one side of the substrate 1.

[0062] In some embodiments, the substrate 1 includes a substrate and a driving circuit layer, the driving circuit layer being disposed on one side of the substrate, and the light-emitting device layer 2 being disposed on the side of the driving circuit layer away from the substrate.

[0063] In some embodiments, the substrate may be a single-layer flexible substrate made of organic material, or a single-layer rigid substrate made of inorganic material. The substrate may also be a multilayer flexible substrate formed by stacking at least one layer of organic material and at least one layer of inorganic material. The organic material may be transparent polyimide, and the inorganic material may be glass.

[0064] In some embodiments, the driving circuit layer may be provided with pixel driving circuits and signal traces for driving the light-emitting device to emit light. The film structure of the driving circuit layer may refer to the film structure of the driving circuit layer of a known organic light-emitting diode display panel, and is not limited here.

[0065] In some embodiments, referring to FIG1, the light-emitting device layer 2 includes an anode 21, a light-emitting layer 22, and a cathode 23 stacked together. The light-emitting layer 22 includes a hole layer 221, an organic light-emitting material layer 222, and an electron layer 223 stacked on the anode 21. The hole layer 221 includes a hole injection layer, a hole transport layer, and a hole blocking layer stacked sequentially on the anode 21. The electron layer 223 includes an electron blocking layer, an electron transport layer, and an electron injection layer stacked sequentially on the organic light-emitting material layer 222.

[0066] In some embodiments, the light-emitting device layer 2 has a plurality of light-emitting devices, which are organic light-emitting diodes (OLEDs). The organic light-emitting diodes include an anode 21, a light-emitting layer 22, and a cathode 23 as described above.

[0067] In some embodiments, referring to FIG1, the display panel 100 further includes a cover layer 3 disposed on the surface of the cathode 23 away from the light-emitting layer 22. The cover layer 3 includes at least one first cover layer 31 and at least one second cover layer 32. The first cover layer 31 is disposed on the surface of the cathode 23 away from the light-emitting layer 22, and the second cover layer 32 is disposed on the side of the first cover layer 31 closest to the cathode 23 away from the cathode 23. The first cover layer 31 and the second cover layer 32 have different refractive indices, and the phase transition temperature of the first cover layer 31 is lower than that of the second cover layer 32.

[0068] In the embodiments of this application, by making the refractive indices of the first cover layer 31 and the second cover layer 32 different, light is caused to undergo multiple reflections and interferences in the microcavity structure of the cover layer 3, thereby enhancing the luminous intensity of light of a specific wavelength, reducing light loss, and thus improving the light extraction efficiency. On this basis, by making the phase transition temperature of the first cover layer 31 lower than that of the second cover layer 32, when the material of the first cover layer 31 comes into contact with the cathode surface with residual heat, the crystallization time of the first cover layer 31 will be extended, and the grain size generated in the first cover layer 31 will be finer, making the film layer at the interface between the first cover layer 31 and the cathode 23 smoother and more uniform. This can improve the light extraction effect of the cover layer 3, thereby improving the light extraction efficiency and stability of the further display panel.

[0069] In some embodiments, the material of the capping layer 3 is an organic material, specifically an aromatic compound. Specifically, the material of the first capping layer 31 has groups such as benzene rings, imides, and phthalimides, and the material of the second capping layer 32 has groups such as benzene rings, benzoxazoles, and oxazoles.

[0070] It should be noted that the phase transition temperature in the embodiments of this application includes the glass transition temperature, the melting temperature, and the sublimation temperature. The phase transition temperature of the first capping layer being lower than that of the second capping layer means that any one of the glass transition temperature, melting temperature, and sublimation temperature of the first capping layer is lower than the corresponding phase transition temperature of the second capping layer. For example, the glass transition temperature of the first capping layer is lower than that of the second capping layer, the melting temperature of the first capping layer is lower than that of the second capping layer, and the sublimation temperature of the first capping layer is lower than that of the second capping layer.

[0071] In some embodiments, the first cover layer 31 has a first glass transition temperature, and the second cover layer 32 has a second glass transition temperature, wherein the first glass transition temperature is lower than the second glass transition temperature. It should be noted that the glass transition temperature determines the starting temperature of the cooling process of the cover layer material. During the vapor deposition process to form the cover layer, the temperature of the cover layer material deposited on the panel gradually decreases to room temperature. Since the vapor deposition process is carried out in a vacuum environment, heat dissipation is slow, and the metal cathode 23 still has residual heat. When the first cover layer 31 comes into contact with the surface of the cathode 23 with residual heat, due to the lower glass transition temperature of the first cover layer 31, the crystallization time of the first cover layer 31 is longer, and the grains generated in the first cover layer 31 are finer. This results in a smoother and more uniform film layer at the interface between the first cover layer 31 and the cathode 23, thereby improving the light emission effect of the cover layer 3 and thus improving the light emission efficiency and stability of the light-emitting device.

[0072] In some embodiments, the difference between the second glass transition temperature and the first glass transition temperature is greater than or equal to 30 degrees Celsius and less than or equal to 40 degrees Celsius. For example, the difference between the second glass transition temperature and the first glass transition temperature can be 30 degrees Celsius, 33 degrees Celsius, 35 degrees Celsius, 37 degrees Celsius, or 40 degrees Celsius, etc. As long as it is between 30 degrees Celsius and 40 degrees Celsius, it can ensure that the film layer at the interface between the first capping layer 31 and the cathode 23 is more flat and uniform. This can improve the light emission effect of the capping layer 3, thereby improving the light emission efficiency and stability of the light-emitting device.

[0073] In some embodiments, the first capping layer 31 has a first melting temperature, and the second capping layer 32 has a second melting temperature, wherein the first melting temperature is lower than the second melting temperature. It should be noted that the melting temperature is also related to the crystallization time of the capping layer; the lower the melting temperature of the capping layer, the longer the crystallization time when in contact with the residual heat cathode. Because the melting temperature of the first capping layer 31 is lower, the crystallization time of the first capping layer 31 is longer, resulting in finer grains in the first capping layer 31. This makes the film at the interface between the first capping layer 31 and the cathode 23 smoother and more uniform, thus improving the light extraction effect of the capping layer 3 and thereby increasing the light extraction efficiency and stability of the light-emitting device.

[0074] In some embodiments, the difference between the second melting temperature and the first melting temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius. For example, the difference between the second melting temperature and the first melting temperature can be 25 degrees Celsius, 27 degrees Celsius, 30 degrees Celsius, 33 degrees Celsius, or 35 degrees Celsius, etc. As long as it is between 25 degrees Celsius and 35 degrees Celsius, it can ensure that the film layer at the interface between the first capping layer 31 and the cathode 23 is smoother and more uniform. This can improve the light emission effect of the capping layer 3, thereby improving the light emission efficiency and stability of the light-emitting device.

[0075] In some embodiments, the first capping layer 31 has a first sublimation temperature, and the second capping layer 32 has a second sublimation temperature, wherein the first sublimation temperature is lower than the second sublimation temperature. It should be noted that the sublimation temperature is also related to the crystallization time of the capping layer; the lower the sublimation temperature of the capping layer, the longer the crystallization time when in contact with the residual heat cathode. Because the first capping layer 31 has a lower sublimation temperature, its crystallization time is longer, resulting in finer grains in the first capping layer 31. This makes the film at the interface between the first capping layer 31 and the cathode 23 smoother and more uniform, thus improving the light extraction effect of the capping layer 3 and thereby increasing the light extraction efficiency and stability of the light-emitting device.

[0076] In some embodiments, the difference between the second sublimation temperature and the first sublimation temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius.

[0077] For example, the difference between the second sublimation temperature and the first sublimation temperature can be 25 degrees Celsius, 27 degrees Celsius, 30 degrees Celsius, 33 degrees Celsius, or 35 degrees Celsius, etc. As long as it is between 25 degrees Celsius and 35 degrees Celsius, it can ensure that the film layer at the interface between the first capping layer 31 and the cathode 23 is smoother and more uniform. This can improve the light emission effect of the capping layer 3, thereby improving the light emission efficiency and stability of the light-emitting device.

[0078] In some embodiments, the first glass transition temperature of the first cover layer 31 is lower than the second glass transition temperature of the second cover layer 32, the first melting temperature of the first cover layer 31 is lower than the second melting temperature of the second cover layer 32, and the first sublimation temperature of the first cover layer 31 is lower than the second sublimation temperature of the second cover layer 32.

[0079] In some embodiments, the display panel 100 includes at least two stacked first cover layers 31, and a second cover layer 32 is disposed between two adjacent first cover layers 31.

[0080] In some embodiments, referring to FIG1, the capping layer 3 includes two first capping layers 31 and one second capping layer 32. The two first capping layers 31 are sequentially stacked on the surface of the cathode 23 away from the light-emitting layer 22, and the second capping layer 32 is disposed between the two first capping layers 31. This allows the capping layer 3 to have a three-layer structure with a continuously changing refractive index, further increasing the number of reflections and interferences of light in the microcavity structure of the capping layer, thereby enhancing the luminous intensity of light of a specific wavelength, reducing light loss, and thus improving the light extraction efficiency.

[0081] In some embodiments, the number of first cover layers 31 in the cover layer 3 is n+1, and the number of second cover layers 32 is n, where n is greater than or equal to 1, and each second cover layer 32 is disposed between two adjacent first cover layers 31.

[0082] In some embodiments, the refractive index of the first capping layer 31 is less than that of the second capping layer 32, and the refractive index of the capping layer 3 exhibits a continuous low / high / low variation. This can increase the number of times light is reflected and interfered in the microcavity structure of the capping layer, reduce total internal reflection of light inside the organic light-emitting device, thereby enhancing the amount of light emitted at a specific wavelength, reducing light loss, and thus improving light extraction efficiency.

[0083] In some embodiments, the refractive index of the first capping layer 31 is greater than or equal to 1.4 and less than or equal to 1.6, and the refractive index of the second capping layer 32 is greater than or equal to 1.8 and less than or equal to 2.1. For example, the refractive index of the first capping layer 31 may be 1.4, 1.5, or 1.6, and the refractive index of the second capping layer 32 may be 1.8, 1.9, 2.0, or 2.1. When the capping layer 3 has multiple first capping layers 31, the refractive indices of the different first capping layers 31 may be the same or different, as long as they are between 1.4 and 1.6. When the capping layer 3 has multiple second capping layers 32, the refractive indices of the different second capping layers 32 may be the same or different, as long as they are between 1.8 and 2.1.

[0084] In some embodiments, the thickness of the first capping layer 31 is less than the thickness of the second capping layer 32. It should be noted that the first capping layer 31, with its lower refractive index, improves the smoothness and uniformity of the film at the interface between the capping layer 31 and the cathode 23, while the second capping layer 32, with its higher refractive index, enhances the light extraction efficiency of the light-emitting device. If the thickness of the first capping layer 31 is too large, it will compress the thickness of the second capping layer 32, leading to a decrease in the light extraction efficiency of the light-emitting device. By making the thickness of the first capping layer 31 less than the thickness of the second capping layer 32, the smoothness and uniformity of the film at the interface between the first capping layer 31 and the cathode 23 can be improved, while also enhancing the light extraction efficiency and stability of the light-emitting device.

[0085] In some embodiments, the thickness of the first capping layer 31 is greater than or equal to 12 nanometers and less than or equal to 18 nanometers, and the thickness of the second capping layer 32 is greater than or equal to 45 nanometers and less than or equal to 70 nanometers. For example, the thickness of the first capping layer 31 is 12 nanometers, 14 nanometers, 16 nanometers, or 18 nanometers, and the thickness of the second capping layer 32 is 45 nanometers, 50 nanometers, 55 nanometers, 60 nanometers, 65 nanometers, or 70 nanometers, etc. It should be noted that if the thickness of the first capping layer 31 is less than 12 nanometers, it cannot effectively improve the smoothness and uniformity of the film layer at the interface between the first capping layer 31 and the cathode 23. If the thickness of the first capping layer 31 is greater than 18 nanometers, it will compress the thickness of the second capping layer 32, resulting in a decrease in the light extraction efficiency and stability of the light-emitting device. If the thickness of the second capping layer 32 is less than 45 nanometers, the light extraction efficiency and stability of the light-emitting device will decrease. If the thickness of the second capping layer 32 is greater than 70 nanometers, it will compress the thickness of the first capping layer 31, resulting in poorer smoothness and uniformity of the film at the interface between the first capping layer 31 and the cathode 23. Therefore, limiting the thickness of the first capping layer 31 and the second capping layer 32 within the above-mentioned range can improve the smoothness and uniformity of the film at the interface between the first capping layer 31 and the cathode 23, while simultaneously improving the light extraction efficiency and stability of the light-emitting device.

[0086] In some embodiments, when the cover layer 3 has multiple first cover layers 31, the thickness of the different first cover layers 31 can be the same or different, and only needs to be between 12 and 18 nanometers. When the cover layer 3 has multiple second cover layers 32, the thickness of the different second cover layers 32 can be the same or different, and only needs to be between 45 and 70 nanometers.

[0087] In some embodiments, referring to FIG1, the display panel 100 further includes an inorganic capping layer 4. The inorganic capping layer 4 is disposed on the surface of a first capping layer 31 furthest from the cathode 23. The material of the inorganic capping layer 4 includes alkali metal halides. Alkali metal halides are highly symmetric crystal structures with high transmittance and low refractive index. Using alkali metal halides to prepare the inorganic capping layer 4 can not only enhance the microcavity effect within the display panel 100, thereby improving the light extraction efficiency of the display panel, but also give the inorganic capping layer 4 high density, enabling it to block water and oxygen, thereby improving the encapsulation effect of the display panel.

[0088] In some embodiments, referring to FIG1, the capping layer 3 has two first capping layers 31 and one second capping layer 32, and the inorganic capping layer 4 is disposed on the surface of the second first capping layer 31 away from the second capping layer 32. Since the phase transition temperature of the first capping layer 31 is low, when the inorganic capping layer 4 containing alkali metal halides is formed by vapor deposition, the alkali metal halide gas molecules, which are still at residual temperature, come into contact with the surface of the already formed first capping layer 31. This is equivalent to the surface of the first capping layer 31 undergoing an annealing process. This can reduce the residual stress of the first capping layer 31, further refine the grains in the first capping layer 31, and make the film at the interface between the first capping layer 31 and the inorganic capping layer 4 more flat and uniform. This further increases the bonding force between the first capping layer 31 and the inorganic capping layer 4 and reduces the risk of cracking at the film interface between the first capping layer 31 and the inorganic capping layer 4.

[0089] In some embodiments, the material of the inorganic capping layer 4 includes lithium fluoride.

[0090] In some embodiments, the refractive index of the inorganic capping layer 4 is less than that of the first capping layer 31, which can enhance the microcavity effect within the display panel 100, thereby improving the light extraction efficiency of the display panel.

[0091] In some embodiments, the refractive index of the inorganic capping layer 4 is greater than or equal to 1.2 and less than or equal to 1.4. For example, the refractive index of the inorganic capping layer 4 is 1.2, 1.25, 1.3, 1.35 or 1.4, etc., which only needs to be between 1.2 and 1.4 and less than the refractive index of the first capping layer 31.

[0092] In some embodiments, please refer to FIG1, the cover layer 3 includes two first cover layers 31 and one second cover layer 32, and the sum of the thickness of the inorganic cover layer 4 and the first cover layer 31 furthest from the cathode 23 is greater than the thickness of the first cover layer 31 closest to the cathode 23.

[0093] In some embodiments, referring to FIG1, the display panel 100 further includes an encapsulation layer 5, which is disposed on the surface of the inorganic cover layer 4 away from the cover layer 3. The encapsulation layer 5 includes a first inorganic encapsulation layer 51, an organic encapsulation layer 52, and a second inorganic encapsulation layer 53 stacked on the surface of the inorganic cover layer 4 away from the cover layer 3.

[0094] In some embodiments, the inorganic cover layer 4 is reused as the first inorganic encapsulation layer 51 of the encapsulation layer 5, which not only reduces the thickness of the display panel but also takes into account the encapsulation effect and light emission efficiency of the display panel.

[0095] In some embodiments, please refer to FIG1, the cover layer 3 includes two first cover layers 31 and one second cover layer 32, and the thickness of the first inorganic encapsulation layer 51 is greater than the sum of the thicknesses of the inorganic cover layer 4 and the second cover layer 32.

[0096] Please refer to Figure 2, which is a schematic diagram of the optical path in the display panel provided in the embodiment of this application. In the embodiment of this application, the design of multiple cover layers can enhance the weak microcavity effect outside the organic light-emitting diode and improve the light extraction efficiency. For example, light ① emitted from the cathode 23 can be reflected between the first cover layer 31 and the second cover layer 32. Part of the reflected light reaches the cathode interface and is reflected to obtain light ②, and part of it reaches the anode 21 interface and is reflected to obtain light ④. Light emitted from the cathode can also be reflected at the interface of the first inorganic encapsulation layer 51 to obtain light ③. Lights ①, ②, ③, and ④ can form multi-beam interference, which enhances the light extraction efficiency. Due to the enhanced microcavity effect, the embodiment of this application has a narrower half-width. On the other hand, the low-refractive-index first cover layer 31 can change the wave vector direction at the cathode 23, reduce the plasma mode on the cathode surface, and allow some of the light confined inside the organic light-emitting diode to be emitted into the air, increasing the coupling light extraction efficiency and reducing the power consumption of the display panel.

[0097] An embodiment of this application also provides a display device, as shown in FIG3. FIG3 is a schematic diagram of the structure of the display device provided in the embodiment of this application. The display device 1000 includes a housing 200 and a display panel 100, and the display panel 100 is disposed on the housing 200. The display panel 100 can be the display panel provided in any of the above embodiments, and the display device 1000 can achieve the same technical effect as the display panel provided in any of the above embodiments, which will not be described in detail here.

[0098] The beneficial effects of the embodiments of this application are as follows: The embodiments of this application provide a display panel and a display device. The display panel includes a substrate, a light-emitting device layer, and a cover layer. The light-emitting device layer is disposed on one side of the substrate and includes an anode, a light-emitting layer, and a cathode stacked together. The cover layer is disposed on the surface of the cathode away from the light-emitting layer and includes at least one first cover layer and at least one second cover layer. By making the refractive indices of the first cover layer and the second cover layer different, the weak microcavity effect outside the light-emitting device layer is enhanced, causing light to undergo multiple reflections and interferences in the microcavity structure of the light-emitting device layer and the cover layer, thereby enhancing the luminous intensity of light of a specific wavelength, reducing light loss, and improving the light extraction efficiency. In addition, by making the phase transition temperature of the first cover layer lower than that of the second cover layer, when the material of the first cover layer comes into contact with the cathode surface with residual heat, the crystallization time of the first cover layer is prolonged, and the grains generated in the first cover layer are finer, making the film layer at the interface between the first cover layer and the cathode more flat and uniform. This can improve the light extraction effect of the cover layer, thereby improving the light extraction efficiency and stability of the display panel.

[0099] In summary, although the present application discloses the preferred embodiments as described above, the above preferred embodiments are not intended to limit the present application. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application is based on the scope defined by the claims.

Claims

1. A display panel, comprising: substrate; A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together; A cover layer is disposed on the surface of the cathode away from the light-emitting layer; The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer away from the cathode. The refractive indices of the first capping layer and the second capping layer are different. The phase transition temperature of the first capping layer is lower than that of the second capping layer.

2. The display panel of claim 1, wherein, The first capping layer has a first glass transition temperature, and the second capping layer has a second glass transition temperature, wherein the first glass transition temperature is lower than the second glass transition temperature.

3. The display panel of claim 2, wherein, The difference between the second glass transition temperature and the first glass transition temperature is greater than or equal to 30 degrees Celsius and less than or equal to 40 degrees Celsius.

4. The display panel of claim 2, wherein, The first cover layer has a first melting temperature, the second cover layer has a second melting temperature, and the first melting temperature is lower than the second melting temperature.

5. The display panel of claim 4, wherein, The difference between the second melting temperature and the first melting temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius.

6. The display panel of claim 2, wherein, The first capping layer has a first sublimation temperature, and the second capping layer has a second sublimation temperature, wherein the first sublimation temperature is lower than the second sublimation temperature.

7. The display panel of claim 6, wherein, The difference between the second sublimation temperature and the first sublimation temperature is greater than or equal to 25 degrees Celsius and less than or equal to 35 degrees Celsius.

8. The display panel of claim 1, wherein, The covering layer includes at least two stacked first covering layers, and the second covering layer is disposed between two adjacent first covering layers.

9. The display panel of claim 8, wherein, The refractive index of the first coating layer is less than that of the second coating layer.

10. The display panel of claim 8, wherein, The refractive index of the first covering layer is greater than or equal to 1.4 and less than or equal to 1.6, and the refractive index of the second covering layer is greater than or equal to 1.8 and less than or equal to 2.

1.

11. The display panel of claim 8, wherein, The thickness of the first covering layer is less than the thickness of the second covering layer.

12. The display panel of claim 8, wherein, The thickness of the first cover layer is greater than or equal to 12 nanometers and less than or equal to 18 nanometers, and the thickness of the second cover layer is greater than or equal to 45 nanometers and less than or equal to 70 nanometers.

13. The display panel of claim 8, wherein, The display panel further includes an inorganic cover layer, which is disposed on the surface of the first cover layer furthest from the cathode. The inorganic coating material includes alkali metal halides.

14. The display panel of claim 13, wherein, The refractive index of the inorganic coating layer is less than that of the first coating layer.

15. The display panel of claim 13, wherein, The refractive index of the inorganic coating layer is greater than or equal to 1.2 and less than or equal to 1.

4.

16. The display panel of claim 13, wherein, The capping layer includes two first capping layers and one second capping layer. The sum of the thickness of the inorganic capping layer and the thickness of the first capping layer furthest from the cathode is greater than the thickness of the first capping layer closest to the cathode.

17. The display panel of claim 13, wherein, The display panel further includes an encapsulation layer disposed on the surface of the inorganic cover layer away from the cover layer. The encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked on the surface of the inorganic cover layer away from the cover layer.

18. The display panel of claim 17, wherein, The cover layer includes two first cover layers and one second cover layer, wherein the thickness of the first inorganic encapsulation layer is greater than the sum of the thicknesses of the inorganic cover layer and the second cover layer.

19. A display device comprising a display panel, the display panel comprising: substrate; A light-emitting device layer is disposed on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode stacked together; A cover layer is disposed on the surface of the cathode away from the light-emitting layer; The capping layer includes at least one first capping layer and at least one second capping layer. The second capping layer is disposed on the side of the first capping layer away from the cathode. The refractive indices of the first capping layer and the second capping layer are different. The phase transition temperature of the first capping layer is lower than that of the second capping layer.

20. The display device of claim 19, wherein, The first capping layer has a first glass transition temperature, and the second capping layer has a second glass transition temperature, wherein the first glass transition temperature is lower than the second glass transition temperature.

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