Display panel and display device

Abstract

The invention provides a display panel and a display device.The display panel comprises a substrate, a light-emitting device layer and covering layers, the covering layers comprise at least one first covering layer and at least one second covering layer, and the refractive indexes of the first covering layer and the second covering layer are different; the phase change temperature of the first covering layer is lower than that of the second covering layer, so that when the material of the first covering layer is in contact with the surface of the cathode, the crystallization film forming time of the first covering layer can be prolonged, crystal grains generated in the first covering layer are finer, a film layer at the interface combination position of the first covering layer and the cathode is smoother, and the service life of the cathode is prolonged. Therefore, the light emitting effect of the covering layer can be improved, and the light emitting efficiency and stability of the display panel can be improved.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a display panel and a display device. Background Art

[0002] Organic Light-Emitting Diode (OLED) is an organic electroluminescent device that emits light through the injection and recombination of carriers. It has the advantages of being light, bright, low power, fast response, high luminous efficiency, good flexibility, and being able to meet consumers' new demands for display forms. More and more panel manufacturers around the world have invested heavily in research and development, greatly promoting the industrialization of organic light-emitting diode display panels.

[0003] With the continuous development of display technology, the requirements for power consumption and stability of display panels are becoming higher and higher. At present, a covering layer is usually set on the cathode of an organic light-emitting diode, and the microcavity structure of the covering layer is used to effectively extract the light generated from the light-emitting layer of the light-emitting diode, thereby improving the light extraction efficiency of the light-emitting diode. However, due to the short crystallization film formation time of the covering layer, the generated grains are large, which makes the interface between the covering layer and the metal cathode uneven, resulting in changes in the microcavity structure in the covering layer, resulting in reduced light extraction efficiency and stability of the organic light-emitting diode.

[0004] Therefore, it is necessary to provide a display panel and a display device to improve this defect. Summary of the invention

[0005] Embodiments of the present application provide a display panel and a display device, which can improve the light extraction efficiency and stability of an organic light emitting diode in the display panel.

[0006] In order to achieve the above object, according to a first aspect of the present application, a display panel is provided, comprising: substrate; A light-emitting device layer is arranged on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode which are stacked; A covering layer, disposed on a surface of the cathode away from the light-emitting layer; Wherein, the covering layer includes at least one first covering layer and at least one second covering layer, the second covering layer is arranged on a side of the first covering layer away from the cathode and closest to the cathode, the refractive index of the first covering layer is smaller than the refractive index of the second covering layer, and the phase change temperature of the first covering layer is smaller than the phase change temperature of the second covering layer.

[0007] 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.

[0008] Optionally, a 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.

[0009] 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.

[0010] Optionally, a 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.

[0011] Optionally, the first covering layer has a first sublimation temperature, the second covering layer has a second sublimation temperature, and the first sublimation temperature is lower than the second sublimation temperature.

[0012] Optionally, a 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.

[0013] Optionally, the covering layer includes at least two stacked first covering layers, and the second covering layer is arranged between two adjacent first covering layers.

[0014] 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.

[0015] Optionally, the thickness of the first covering layer is smaller than the thickness of the second covering layer.

[0016] Optionally, the thickness of the first covering layer is greater than or equal to 12 nanometers and less than or equal to 18 nanometers, and the thickness of the second covering layer is greater than or equal to 45 nanometers and less than or equal to 70 nanometers.

[0017] Optionally, the display panel further comprises an inorganic covering layer, and the inorganic covering layer is arranged on a surface of the first covering layer which is farthest from the cathode and away from the cathode; Wherein, the material of the inorganic cover layer includes alkali metal halide.

[0018] Optionally, a refractive index of the inorganic cover layer is smaller than a refractive index of the first cover layer.

[0019] Optionally, the refractive index of the inorganic cover layer is greater than or equal to 1.2 and less than or equal to 1.4.

[0020] Optionally, the covering layer includes two layers of the first covering layer and one layer of the second covering layer, and the sum of the thicknesses of the inorganic covering layer and the first covering layer farthest from the cathode is greater than the thickness of the first covering layer closest to the cathode.

[0021] Optionally, the display panel further includes an encapsulation layer, which is disposed on a surface of the inorganic covering layer away from the covering layer, and the encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked on a surface of the inorganic covering layer away from the covering layer.

[0022] Optionally, the covering layer includes two layers of the first covering layer and one layer of the second covering layer, and the thickness of the first inorganic encapsulation layer is greater than the sum of the thicknesses of the inorganic covering layer and the second covering layer.

[0023] According to a second aspect of the present application, a display device is provided, comprising a display panel as described in any one of the above embodiments.

[0024] In the display panel of the embodiment of the present application, the refractive index of the first covering layer and the second covering layer is made different, so as to enhance the weak microcavity effect outside the light-emitting device layer, so that the light is reflected and interfered multiple times in the microcavity structure of the light-emitting device layer and the covering layer, so as to enhance the luminous intensity of light of a specific wavelength, reduce light loss, and thus improve the light extraction efficiency. On this basis, by making the phase change temperature of the first covering layer lower than the phase change temperature of the second covering layer, when the material of the first covering layer contacts the cathode surface with residual temperature, the crystallization film forming time of the first covering layer will be extended, and the grains generated in the first covering layer will be finer, so that the film layer at the interface between the first covering layer and the cathode will be smoother and more uniform, thereby improving the light extraction effect of the covering layer, thereby further improving the light extraction efficiency and stability of the display panel.

[0025] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0027] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0028] Figure 1 A schematic diagram of the film layer structure of a display panel provided in an embodiment of the present application; Figure 2 A schematic diagram of a light path in a display panel provided in an embodiment of the present application; Figure 3 A schematic diagram of the structure of a display device provided in an embodiment of the present application.

[0029] Description of reference numerals: 1. Substrate; 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; 3. Covering layer; 31. First covering layer; 32. Second covering layer; 4. Inorganic covering layer; 5. Encapsulation layer; 51. First inorganic encapsulation layer; 52. Organic encapsulation layer; 53. Second inorganic encapsulation layer; 201, buffer layer; 202, active layer; 203, first gate insulating layer; 204, first gate layer; 205, second gate insulating layer; 206, second gate layer; 207, interlayer dielectric layer; 208, first source-drain electrode layer; 209, first planar layer; 210, second source-drain electrode layer; 211, second planar layer; 20, driving circuit unit; 21, first pixel driving circuit; 22, second pixel driving circuit; 3. Light-emitting device layer; 301. Anode; 302. Pixel definition layer; 303. Spacer layer; 31. Light-emitting device; 1000. Display device; 100. Display panel; 200. Housing. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0031] The present application provides a display panel, which includes a substrate, a light-emitting device layer and a covering layer. The light-emitting device layer is arranged on one side of the substrate, the light-emitting device layer includes an anode, a light-emitting layer and a cathode arranged in a stacked manner, the covering layer is arranged on a surface of the cathode away from the light-emitting layer, the covering layer includes at least one first covering layer and at least one second covering layer, the second covering layer is arranged on a side of the first covering layer closest to the cathode away from the cathode, the refractive index of the first covering layer and the second covering layer are different, and the phase change temperature of the first covering layer is lower than the phase change temperature of the second covering layer.

[0032] In this embodiment, the refractive index of the first covering layer is different from that of the second covering layer, so as to enhance the weak microcavity effect outside the light-emitting device layer, so that the light is reflected and interfered multiple times in the microcavity structure of the light-emitting device layer and the covering layer, so as to enhance the luminous intensity of light of a specific wavelength, reduce light loss, and thus improve the light extraction efficiency. On this basis, by making the phase change temperature of the first covering layer lower than the phase change temperature of the second covering layer, when the material of the first covering layer contacts the cathode surface with residual temperature, the crystallization film forming time of the first covering layer will be extended, and the grains generated in the first covering layer will be finer, so that the film layer at the interface between the first covering layer and the cathode will be smoother and more uniform, so that the light extraction effect of the covering layer can be improved, thereby further improving the light extraction efficiency and stability of the display panel.

[0033] Combination Figure 1 As shown, Figure 1 The schematic diagram of the film layer structure of the display panel provided in the embodiment of the present application is as follows: the display panel 100 includes a substrate 1 and a light-emitting device layer 2 , and the light-emitting device layer 2 is arranged on one side of the substrate 1 .

[0034] In some embodiments, the substrate 1 includes a substrate and a driving circuit layer, the driving circuit layer is disposed on one side of the substrate, and the light emitting device layer 2 is disposed on a side of the driving circuit layer away from the substrate.

[0035] In some embodiments, the substrate can be a single-layer flexible substrate made of an organic material, the substrate can be a single-layer hard substrate made of an inorganic material, or the substrate can be a multi-layer flexible substrate formed by stacking at least one layer of organic material and at least one layer of inorganic material. The organic material can be transparent polyimide and the inorganic material can be glass.

[0036] In some embodiments, the driving circuit layer may be provided with a pixel driving circuit and a signal line for driving the light-emitting device to emit light. The film layer structure of the driving circuit layer may refer to the film layer structure of the driving circuit layer of a known organic light-emitting diode display panel, and is not limited here.

[0037] In some embodiments, see Figure 1 The light-emitting device layer 2 includes an anode 21, a light-emitting layer 22 and a cathode 23 which are stacked together. The light-emitting layer 22 includes a hole layer 221, an organic light-emitting material layer 222 and an electron layer 223 which are stacked on the anode 21. The hole layer 221 includes a hole injection layer, a hole transport layer and a hole blocking layer which are stacked in sequence on the anode 21. The electron layer 223 includes an electron blocking layer, an electron transport layer and an electron injection layer which are stacked in sequence on the organic light-emitting material layer 222.

[0038] In some embodiments, the light-emitting device layer 2 has a plurality of light-emitting devices, and the light-emitting devices are organic light-emitting diodes. The organic light-emitting diodes include the anode 21, the light-emitting layer 22 and the cathode 23 as described above.

[0039] In some embodiments, see Figure 1 The display panel 100 further includes a covering layer 3, which is disposed on the surface of the cathode 23 away from the light-emitting layer 22. The covering layer 3 includes at least one first covering layer 31 and at least one second covering layer 32, wherein the first covering layer 31 is disposed on the surface of the cathode 23 away from the light-emitting layer 22, and the second covering layer 32 is disposed on a side of the first covering layer 31 away from the cathode 23 that is closest to the cathode 23. The refractive indexes of the first covering layer 31 and the second covering layer 32 are different, and the phase transition temperature of the first covering layer 31 is lower than the phase transition temperature of the second covering layer 32.

[0040] In the embodiment of the present application, by making the refractive index of the first covering layer 31 and the second covering layer 32 different, the light is reflected and interfered multiple times in the microcavity structure of the covering layer 3, so as to enhance the luminous intensity of the light of a specific wavelength, reduce the light loss, and thus improve the light extraction efficiency. On this basis, by making the phase change temperature of the first covering layer 31 lower than the phase change temperature of the second covering layer 32, when the material of the first covering layer 31 contacts the cathode surface with residual temperature, the crystallization film forming time of the first covering layer 31 will be extended, and the grain size generated in the first covering layer 31 will be finer, so that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, so that the light extraction effect of the covering layer 3 can be improved, thereby further improving the light extraction efficiency and stability of the display panel.

[0041] In some embodiments, the material of the cover layer 3 is an organic material, which can be an aromatic compound. Specifically, the material of the first cover layer 31 has groups such as benzene ring, imide, phthalimide, etc., and the material of the second cover layer 32 has groups such as benzene ring, benzene oxazole, oxazole, etc.

[0042] It should be noted that the phase change temperature in the embodiments of the present application includes the glass transition temperature, the melting temperature and the sublimation temperature. The phase change temperature of the first covering layer is lower than the phase change temperature of the second covering layer, which means that any one of the glass transition temperature, the melting temperature and the sublimation temperature of the first covering layer is lower than the corresponding phase change temperature of the second covering layer. For example, the glass transition temperature of the first covering layer is lower than the glass transition temperature of the second covering layer, the melting temperature of the first covering layer is lower than the melting temperature of the second covering layer, and the sublimation temperature of the first covering layer is lower than the sublimation temperature of the second covering layer.

[0043] In some embodiments, the first covering layer 31 has a first glass transition temperature, the second covering layer 32 has a second glass transition temperature, and the first glass transition temperature is less 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 covering layer material. When the covering layer is formed by evaporation, the temperature of the covering layer material evaporated on the panel gradually decreases to room temperature. Since the evaporation process is carried out in a vacuum environment, the heat dissipation is slow, and the cathode 23 of the metal material still has residual temperature. When the first covering layer 31 contacts the surface of the cathode 23 with residual temperature, due to the low glass transition temperature of the first covering layer 31, the crystallization film formation time of the first covering layer 31 is longer, and the grains generated in the first covering layer 31 are finer, so that the film layer at the interface of the first covering layer 31 and the cathode 23 is smoother and more uniform, so that the light emitting effect of the covering layer 3 can be improved, thereby improving the light emitting efficiency and stability of the light emitting device.

[0044] 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. It only needs to be between 30 degrees Celsius and 40 degrees Celsius to ensure that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, so that the light extraction effect of the covering layer 3 can be improved, thereby improving the light extraction efficiency and stability of the light emitting device.

[0045] In some embodiments, the first covering layer 31 has a first melting temperature, the second covering layer 32 has a second melting temperature, and the first melting temperature is less than the second melting temperature. It should be noted that the melting temperature is also related to the crystallization film-forming time of the covering layer. The lower the melting temperature of the covering layer, the longer the crystallization film-forming time when in contact with the cathode with residual temperature. Since the melting temperature of the first covering layer 31 is relatively low, the crystallization film-forming time of the first covering layer 31 is longer, and the grains generated in the first covering layer 31 are finer, so that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, which can improve the light-emitting effect of the covering layer 3, thereby improving the light-emitting efficiency and stability of the light-emitting device.

[0046] 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. It only needs to be between 25 degrees Celsius and 35 degrees Celsius to ensure that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, so that the light extraction effect of the covering layer 3 can be improved, thereby improving the light extraction efficiency and stability of the light emitting device.

[0047] In some embodiments, the first covering layer 31 has a first sublimation temperature, the second covering layer 32 has a second sublimation temperature, and the first sublimation temperature is less than the second sublimation temperature. It should be noted that the sublimation temperature is also related to the crystallization film-forming time of the covering layer. The lower the sublimation temperature of the covering layer, the longer the crystallization film-forming time when in contact with the cathode with residual temperature. Since the sublimation temperature of the first covering layer 31 is relatively low, the crystallization film-forming time of the first covering layer 31 is longer, and the grains generated in the first covering layer 31 are finer, so that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, which can improve the light-emitting effect of the covering layer 3, thereby improving the light-emitting efficiency and stability of the light-emitting device.

[0048] 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.

[0049] 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. It only needs to be between 25 degrees Celsius and 35 degrees Celsius to ensure that the film layer at the interface between the first covering layer 31 and the cathode 23 is smoother and more uniform, which can improve the light-emitting effect of the covering layer 3, thereby improving the light-emitting efficiency and stability of the light-emitting device.

[0050] In some embodiments, the first glass transition temperature of the first covering layer 31 is lower than the second glass transition temperature of the second covering layer 32 , the first melting temperature of the first covering layer 31 is lower than the second melting temperature of the second covering layer 32 , and the first sublimation temperature of the first covering layer 31 is lower than the second sublimation temperature of the second covering layer 32 .

[0051] In some embodiments, the display panel 100 includes at least two stacked first covering layers 31 , and the second covering layer 32 is disposed between two adjacent first covering layers 31 .

[0052] In some embodiments, see Figure 1 The cover layer 3 includes two first cover layers 31 and one second cover layer 32. The two first cover layers 31 are sequentially stacked on the surface of the cathode 23 away from the light-emitting layer 22, and the second cover layer 32 is arranged between the two first cover layers 31. In this way, the cover layer 3 can 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 cover layer, thereby enhancing the luminous intensity of light of a specific wavelength, reducing light loss, and thus improving light extraction efficiency.

[0053] In some embodiments, the number of the first covering layers 31 in the covering layer 3 is n+1, the number of the second covering layers 32 is n, wherein n is greater than or equal to 1, and each second covering layer 32 is disposed between two adjacent first covering layers 31 .

[0054] In some embodiments, the refractive index of the first covering layer 31 is less than the refractive index of the second covering layer 32, and the refractive index of the covering layer 3 presents a continuous change of low / high / low, which can increase the number of reflections and interferences of light in the microcavity structure of the covering layer, reduce the total reflection of light inside the organic light-emitting device, thereby enhancing the emission of light of a specific wavelength, reducing light loss, and thus improving light extraction efficiency.

[0055] In some embodiments, the refractive index of the first cover 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 cover 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 cover layer 31 is 1.4, 1.5 or 1.6, and the refractive index of the second cover layer 32 is 1.8, 1.9, 2.0 or 2.1. When the cover layer 3 has multiple layers of first cover layers 31, the refractive indexes of different first cover layers 31 can be the same or different, and only need to be between 1.4 and 1.6. When the cover layer 3 has multiple layers of second cover layers 32, the refractive indexes of different second cover layers 32 can be the same or different, and only need to be between 1.8 and 2.1.

[0056] In some embodiments, the thickness of the first covering layer 31 is less than the thickness of the second covering layer 32. It should be noted that the function of the first covering layer 31 with a lower refractive index is to improve the flatness and uniformity of the film layer at the interface between the covering layer 3 and the cathode 23, and the function of the second covering layer 32 with a higher refractive index is to improve the light extraction efficiency of the light emitting device. If the thickness of the first covering layer 31 is too large, the thickness of the second covering layer 32 will be squeezed, resulting in a decrease in the light extraction efficiency of the light emitting device. By making the thickness of the first covering layer 31 smaller than the thickness of the second covering layer 32, the flatness and uniformity of the film layer at the interface between the first covering layer 31 and the cathode 23 can be improved, while the light extraction efficiency and stability of the light emitting device can also be improved.

[0057] In some embodiments, the thickness of the first covering layer 31 is greater than or equal to 12 nanometers and less than or equal to 18 nanometers, and the thickness of the second covering 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 covering layer 31 is 12 nanometers, 14 nanometers, 16 nanometers or 18 nanometers, and the thickness of the second covering layer 32 is 45 nanometers, 50 nanometers, 55 nanometers, 60 nanometers, 65 nanometers or 70 nanometers. It should be noted that if the thickness of the first covering layer 31 is less than 12 nanometers, the flatness and uniformity of the film layer at the interface between the first covering layer 31 and the cathode 23 cannot be effectively improved. If the thickness of the first covering layer 31 is greater than 18 nanometers, the thickness of the second covering layer 32 will be compressed, resulting in reduced light extraction efficiency and stability of the light-emitting device. If the thickness of the second covering layer 32 is less than 45 nanometers, the light extraction efficiency and stability of the light emitting device will be reduced. If the thickness of the second covering layer 32 is greater than 70 nanometers, the thickness of the first covering layer 31 will be compressed, resulting in poor flatness and uniformity of the film layer at the interface between the first covering layer 31 and the cathode 23. Therefore, limiting the thickness of the first covering layer 31 and the second covering layer 32 within the above range can improve the flatness and uniformity of the film layer at the interface between the first covering layer 31 and the cathode 23, while improving the light extraction efficiency and stability of the light emitting device.

[0058] In some embodiments, when the cover layer 3 has multiple first cover layers 31, the thicknesses of different first cover layers 31 may be the same or different, and only need to be between 12 and 18 nanometers. When the cover layer 3 has multiple second cover layers 32, the thicknesses of different second cover layers 32 may be the same or different, and only need to be between 45 and 70 nanometers.

[0059] In some embodiments, see Figure 1 The display panel 100 further includes an inorganic cover layer 4, which is disposed on a surface of a first cover layer 31 farthest from the cathode 23 and away from the cathode 23, and the material of the inorganic cover layer 4 includes an alkali metal halide. The alkali metal halide is a crystal with a high symmetric lattice structure and has the characteristics of high transmittance and low refractive index. The use of alkali metal halide to prepare the inorganic cover layer 4 can not only enhance the microcavity effect in the display panel 100, thereby improving the light extraction efficiency of the display panel, but also make the inorganic cover layer 4 have a higher density, so that the inorganic cover layer 4 has the function of blocking water and oxygen, thereby improving the packaging effect of the display panel.

[0060] In some embodiments, see Figure 1The cover layer 3 has two first cover layers 31 and one second cover layer 32, and the inorganic cover layer 4 is arranged on the surface of the second first cover layer 31 away from the second cover layer 32. Since the phase change temperature of the first cover layer 31 is relatively low, when the inorganic cover layer 4 containing alkali metal halide is formed by evaporation, when the alkali metal halide gas molecules with residual temperature still contact the surface of the formed first cover layer 31, the surface layer of the first cover layer 31 is equivalent to undergoing an annealing process, which can reduce the residual stress of the first cover layer 31, further refine the grains in the first cover layer 31, make the film layer at the interface of the first cover layer 31 and the inorganic cover layer 4 more flat and uniform, further increase the bonding force between the first cover layer 31 and the inorganic cover layer 4, and reduce the risk of cracking at the film interface between the first cover layer 31 and the inorganic cover layer 4.

[0061] In some embodiments, the material of the inorganic cover layer 4 includes lithium fluoride.

[0062] In some embodiments, the refractive index of the inorganic cover layer 4 is smaller than the refractive index of the first cover layer 31 , which can enhance the microcavity effect in the display panel 100 , thereby improving the light extraction efficiency of the display panel. In some embodiments, the refractive index of the inorganic cover 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 cover layer 4 is 1.2, 1.25, 1.3, 1.35 or 1.4, etc. It only needs to be between 1.2 and 1.4 and less than the refractive index of the first cover layer 31.

[0063] In some embodiments, see Figure 1 The covering layer 3 includes two first covering layers 31 and one second covering layer 32 , and the sum of the thicknesses of the inorganic covering layer 4 and the first covering layer 31 farthest from the cathode 23 is greater than the thickness of the first covering layer 31 closest to the cathode 23 .

[0064] In some embodiments, see Figure 1 The display panel 100 also includes an encapsulation layer 5, which is arranged on the surface of the inorganic cover layer 4 away from the cover layer 3, and 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.

[0065] In some embodiments, the inorganic cover layer 4 is reused as the first inorganic encapsulation layer 51 of the encapsulation layer 5 , which can not only reduce the thickness of the display panel but also take into account the encapsulation effect and light extraction efficiency of the display panel.

[0066] In some embodiments, see Figure 1The covering layer 3 includes two layers of the first covering layer 31 and one layer of the second covering layer 32 , and the thickness of the first inorganic encapsulation layer 51 is greater than the sum of the thicknesses of the inorganic covering layer 4 and the second covering layer 32 .

[0067] See also Figure 2 , Figure 2 The optical path schematic diagram in the display panel provided for the embodiment of the present application, in the embodiment of the present application, through the design of the multi-layer covering layer, on the one hand, the weak microcavity effect outside the organic light emitting diode can be enhanced, and the light extraction efficiency can be enhanced. For example, the light ① emitted from the cathode 23 can be reflected between the first covering layer 31 and the second covering layer 32, and part of the reflected light reaches the cathode interface and is reflected to obtain light ②, and part reaches the anode 21 interface and is reflected to obtain light ④. The light emitted from the cathode can also be reflected when reaching the interface of the first inorganic encapsulation layer 51 to obtain light ③. Lights ①, ②, ③, and ④ can form multi-beam interference to enhance the light extraction efficiency. Due to the enhanced microcavity effect, the embodiment of the present application has a narrower half-peak width; on the other hand, the first covering layer 31 with a low refractive index can change the wave vector direction at the cathode 23, reduce the cathode surface plasma mode, and allow part of the light confined inside the organic light emitting diode to be emitted into the air, increase the coupling light extraction efficiency, and reduce the power consumption of the display panel.

[0068] The embodiment of the present application also provides a display device, such as Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of a display device provided in an embodiment of the present application, wherein 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 may be a display panel provided in any of the above embodiments, and the display device 1000 may achieve the same technical effect as the display panel provided in any of the above embodiments, which will not be described in detail herein.

[0069] Beneficial effects of the embodiments of the present application: The embodiments of the present application provide a display panel and a display device, the display panel includes a substrate, a light-emitting device layer and a covering layer, the light-emitting device layer is arranged on one side of the substrate, the light-emitting device layer includes a stacked anode, a light-emitting layer and a cathode, the covering layer is arranged on the surface of the cathode away from the light-emitting layer, and the covering layer includes at least one first covering layer and at least one second covering layer. By making the refractive index of the first covering layer different from that of the second covering layer, the weak microcavity effect outside the light-emitting device layer is enhanced, so that the light is reflected and interfered multiple times in the microcavity structure of the light-emitting device layer and the covering layer, so as to enhance the luminous intensity of light of a specific wavelength, reduce light loss, and thus improve the light extraction efficiency. On this basis, by making the phase change temperature of the first covering layer lower than the phase change temperature of the second covering layer, when the material of the first covering layer contacts the cathode surface with residual temperature, the crystallization film forming time of the first covering layer will be extended, and the grains generated in the first covering layer will be finer, so that the film layer at the interface of the first covering layer and the cathode will be smoother and more uniform, so that the light extraction effect of the covering layer can be improved, thereby further improving the light extraction efficiency and stability of the display panel.

[0070] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0071] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0072] The embodiments, implementation methods and related technical features of the present application can be combined and replaced with each other without conflict.

[0073] The above are only preferred embodiments of the present application and do not constitute any form of limitation to the present application. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A display panel, characterized in that: include: substrate; A light-emitting device layer is arranged on one side of the substrate, and the light-emitting device layer includes an anode, a light-emitting layer and a cathode which are stacked; A covering layer, disposed on a surface of the cathode away from the light-emitting layer; The covering layer includes at least one first covering layer and at least one second covering layer, the second covering layer is arranged on a side of the first covering layer away from the cathode, the first covering layer and the second covering layer have different refractive indices, and the phase change temperature of the first covering layer is lower than the phase change temperature of the second covering layer.

2. The display panel according to claim 1, wherein: The first cover layer has a first glass transition temperature, and the second cover layer has a second glass transition temperature, and the first glass transition temperature is lower than the second glass transition temperature.

3. The display panel according to claim 2, wherein: A 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 according to claim 2, wherein: The first cover layer has a first melting temperature, and the second cover layer has a second melting temperature, the first melting temperature being lower than the second melting temperature.

5. The display panel according to claim 4, wherein: A 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 according to claim 2, wherein: The first cover layer has a first sublimation temperature, and the second cover layer has a second sublimation temperature, and the first sublimation temperature is lower than the second sublimation temperature.

7. The display panel according to claim 6, wherein: A 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 according to claim 1, wherein: The covering layer includes at least two stacked first covering layers, and the second covering layer is arranged between two adjacent first covering layers.

9. The display panel according to claim 8, wherein: The refractive index of the first cover layer is smaller than the refractive index of the second cover layer.

10. The display panel according to 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 according to claim 8, wherein: The thickness of the first covering layer is smaller than the thickness of the second covering layer.

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

13. The display panel according to claim 8, wherein: The display panel further comprises an inorganic covering layer, wherein the inorganic covering layer is disposed on a surface of the first covering layer which is farthest from the cathode and away from the cathode; Wherein, the material of the inorganic cover layer includes alkali metal halide.

14. The display panel according to claim 13, wherein: The inorganic cover layer has a refractive index lower than that of the first cover layer.

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

4.

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

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

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

19. A display device, characterized in that: Comprising the display panel as claimed in any one of claims 1 to 18.

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