Display panel and display device

Abstract

The application relates to a display panel and a display device; the display panel comprises a first light-emitting device and a second light-emitting device; the first light-emitting device comprises a first light-emitting layer, the first light-emitting layer comprises a first host material and a first guest material, and the first guest material comprises a metal complex and a fluorescent material; wherein the second light-emitting device comprises a second light-emitting layer and a third light-emitting layer which are arranged in a stack, the second light-emitting layer and the third light-emitting layer emit light of the same color, and the first light-emitting layer and the second light-emitting layer emit light of different colors; the application can effectively improve the light-emitting efficiency and the service life of the second light-emitting device through the double light-emitting layers, thereby reducing the probability of display unevenness caused by the high efficiency and the long service life of the first light-emitting device, improving the display uniformity of the display panel, and improving the light-emitting efficiency and the service life of the display panel.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a display panel and display device. Background Technology

[0002] Organic light-emitting diodes (OLEDs), also known as organic electroluminescent devices, are a technology that converts electrical energy into light energy through organic light-emitting materials. This technology involves applying voltage to an organic electroluminescent element to inject holes from the anode and electrons from the cathode into the light-emitting layer. The injected holes and electrons then recombine to form excitons, causing light to be emitted.

[0003] Most OLED devices use a host-guest light-emitting system in their light-emitting layers, which means that guest materials are doped into the host material; while phosphorescent devices have ultra-high efficiency and have become the next generation of OLED technology.

[0004] However, the use of phosphorescent devices in some light-emitting devices can lead to uneven display. For example, when a display panel includes a green phosphorescent device, the green phosphorescent device has a longer high-temperature lifespan and higher low grayscale efficiency after high temperature, which may result in a greening problem after reliability testing (RA). Summary of the Invention

[0005] This application provides a display panel and display device that can effectively improve the luminous efficiency and lifespan of the first light-emitting device and improve the display uniformity of the display panel.

[0006] This application provides a display panel, which includes a first light-emitting device and a second light-emitting device;

[0007] The first light-emitting device includes a first light-emitting layer, which includes a first host material and a first guest material. The first guest material includes a metal complex and a fluorescent material.

[0008] The second light-emitting device includes a second light-emitting layer and a third light-emitting layer stacked together. The second light-emitting layer and the third light-emitting layer emit light of the same color, while the first light-emitting layer and the second light-emitting layer emit light of different colors.

[0009] In one embodiment of this application, the display panel further includes a first electrode layer and a second electrode layer disposed on opposite sides of the first light-emitting layer, and the second electrode layer is disposed close to the display surface of the display panel;

[0010] The first light-emitting layer has at least one concentration partition along the stacking direction from the first electrode layer to the second electrode layer. Within the concentration partition, along the stacking direction, the mass percentage of the first guest material in the first light-emitting layer first increases and then decreases with the increase of the thickness of the first light-emitting layer.

[0011] In one embodiment of this application, the second light-emitting layer includes a second host material and a second guest material, and the third light-emitting layer includes a third host material and a third guest material;

[0012] The second light-emitting layer and the third light-emitting layer are stacked between the first electrode layer and the second electrode layer. The stacking direction is the direction from the second light-emitting layer to the third light-emitting layer. Along the stacking direction, the mass ratio of the second guest material in the second light-emitting layer increases with the increase of the thickness of the second light-emitting layer.

[0013] Along the stacking direction, the mass percentage of the third object material in the third light-emitting layer first decreases and then increases with the increase of the thickness of the third light-emitting layer.

[0014] In one embodiment of this application, within a concentration zone near the first electrode layer, the thickness of the first light-emitting layer at the location where the first guest material has the maximum mass percentage is greater than or equal to the thickness of the second light-emitting layer.

[0015] In one embodiment of this application, the second body material and the third body material are different.

[0016] In one embodiment of this application, the second guest material and the third guest material may be the same or different, and are selected from at least one of metal complexes, thermally activated delayed fluorescent materials, and fluorescent materials containing element B.

[0017] In one embodiment of this application, the second guest material and the third guest material are different and are selected from fluorescent materials, and the horizontal molecular orientation of the third guest material is greater than that of the second guest material;

[0018] And / or, the full width at half maximum (FWHM) of the emission spectrum of the third guest material is smaller than that of the emission spectrum of the second guest material;

[0019] And / or, the shoulder peak of the emission spectrum of the third guest material is smaller than the shoulder peak of the emission spectrum of the second guest material.

[0020] In one embodiment of this application, the second guest material and the third guest material are the same and selected from fluorescent materials, and the horizontal molecular orientation of the second guest material and the horizontal molecular orientation of the third guest material are both greater than or equal to 80%.

[0021] And / or, the full width at half maximum (FWHM) of the emission spectrum of the third guest material and the full width at half maximum (FWHM) of the emission spectrum of the second guest material are both less than or equal to 40 nm;

[0022] And / or, the proportion of the shoulder height of the emission spectrum of the third guest material and the proportion of the shoulder height of the emission spectrum of the second guest material are both less than or equal to 0.3.

[0023] In one embodiment of this application, the second guest material is selected from metal complexes, or metal complexes and fluorescent materials; the third guest material is selected from boron-containing fluorescent materials.

[0024] In one embodiment of this application, the shoulder peak of the emission spectrum of the third guest material is smaller than the shoulder peak of the emission spectrum of the second guest material, and the absolute value of the difference between the peak value of the emission spectrum of the second guest material and the peak value of the emission spectrum of the third guest material is less than or equal to 20 nm.

[0025] In one embodiment of this application, the first light-emitting device further includes a fourth light-emitting layer stacked with the first light-emitting layer, and the fourth light-emitting layer and the first light-emitting layer emit light of the same color.

[0026] In one embodiment of this application, the first light-emitting device is a green light-emitting device or a red light-emitting device, and the second light-emitting device is a blue light-emitting device.

[0027] In accordance with the above-mentioned objectives of this application, embodiments of this application also provide a display device, the display device including the display panel.

[0028] This application provides a display panel and a display device. The first guest material in the first light-emitting device includes a metal complex and a fluorescent material, thereby giving the first light-emitting device high luminous efficiency and lifespan. At the same time, a second light-emitting layer and a third light-emitting layer are stacked in the second light-emitting device. The dual light-emitting layers effectively improve the luminous efficiency and lifespan of the second light-emitting device, thereby reducing the probability of display unevenness caused by the high efficiency and long lifespan of the first light-emitting device, improving the display uniformity of the display panel, and enhancing the luminous efficiency and lifespan of the display panel.

[0029] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0032] Figure 1 This is a schematic diagram of a first structure of an organic light-emitting device provided in an embodiment of this application;

[0033] Figure 2 This is a schematic diagram of a second structure of the organic light-emitting device provided in the embodiments of this application;

[0034] Figure 3 This is a schematic diagram of a third structure of the organic light-emitting device provided in the embodiments of this application;

[0035] Figure 4 This is a schematic diagram of a fourth structure of an organic light-emitting device provided in the embodiments of this application;

[0036] Figure 5 A schematic diagram showing the distribution of the guest material in the first light-emitting device provided in an embodiment of this application;

[0037] Figure 6 This is a schematic diagram showing the distribution of the guest material in the second light-emitting device provided in an embodiment of this application;

[0038] Figure 7 This is a schematic diagram showing the distribution of the guest material in a single-layer light-emitting layer in one embodiment;

[0039] Figure 8 This is a schematic diagram illustrating another distribution of the guest material in the first light-emitting device provided in an embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 101. First light-emitting device; 102. Second light-emitting device; 11. First electrode layer; 111. First sub-electrode; 112. Second sub-electrode; 12. Second electrode layer; 21. First light-emitting layer; 210. Concentration zone; 22. Second light-emitting layer; 23. Third light-emitting layer; 31. Hole injection layer; 32. Hole transport layer; 33. Electron transport layer; 34. Electron injection layer; 35. Electron blocking layer; 36. Hole blocking layer; 37. Light extraction layer; 301. Functional layer; 40. Single-layer light-emitting layer. Detailed Implementation

[0042] 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 protection scope of this application.

[0043] Please combine Figure 1 as well as Figure 2 This application provides a display panel, which includes a first light-emitting device 101 and a second light-emitting device 102.

[0044] The first light-emitting device 101 includes a first light-emitting layer 21, which includes a first host material and a first guest material. The first guest material includes a metal complex and a fluorescent material.

[0045] The second light-emitting device 102 includes a second light-emitting layer 22 and a third light-emitting layer 23 stacked together. The second light-emitting layer 22 and the third light-emitting layer 23 emit light of the same color, while the first light-emitting layer 21 and the second light-emitting layer 22 emit light of different colors.

[0046] In the implementation and application process, in the display panel provided by the embodiments of this application, the first guest material in the first light-emitting device 101 includes a metal complex and a fluorescent material, thereby giving the first light-emitting device 101 high luminous efficiency and lifespan. At the same time, the second light-emitting layer 22 and the third light-emitting layer 23 are stacked in the second light-emitting device 102. The luminous efficiency and lifespan of the second light-emitting device 102 are effectively improved by the dual light-emitting layers, thereby reducing the probability of display unevenness caused by the high efficiency and long lifespan of the first light-emitting device 101, improving the display uniformity of the display panel, and enhancing the luminous efficiency and lifespan of the display panel.

[0047] Specifically, the display panel includes an array substrate and a plurality of light-emitting devices disposed on the array substrate, wherein the plurality of light-emitting devices are arranged in an array, and the plurality of light-emitting devices may include blue light-emitting devices, green light-emitting devices and red light-emitting devices.

[0048] In some embodiments, the array substrate includes a substrate and a thin-film transistor layer disposed on the substrate, and each of the light-emitting devices is connected to the thin-film transistor in the array substrate to realize signal transmission.

[0049] In some embodiments, the substrate may be a rigid substrate, such as a glass substrate; or the substrate may be a flexible substrate, such as a substrate formed of polyimide. When the substrate is a flexible substrate, the substrate may be formed of multiple sub-substrates of the same material, such as polyimide, and adjacent sub-substrates may be bonded together by adhesive sub-layers.

[0050] In some embodiments, the thin-film transistor layer includes a thin-film transistor comprising a semiconductor located on the substrate, the semiconductor being formed of polycrystalline silicon or a metal oxide (such as indium gallium zinc oxide). The semiconductor is divided into a channel region and source and drain regions formed on either side of the channel region. The thin-film transistor layer further includes a first gate insulating layer covering the semiconductor. The thin-film transistor also includes a first gate formed on the first gate insulating layer, the first gate overlapping the channel region. The first gate may be formed as multiple layers or a single layer comprising a low-resistance material such as Al, Ti, Mo, Cu, Ni, or alloys thereof, or a material with high corrosion resistance. The thin-film transistor layer further includes a second gate insulating layer covering the first gate. The thin-film transistor also includes a second gate located on the second gate insulating layer, the second gate overlapping the first gate, the second gate being formed as multiple layers or a single layer comprising a low-resistance material such as Al, Ti, Mo, Cu, Ni, or alloys thereof, or a material with high corrosion resistance. The thin-film transistor layer further includes a first interlayer insulating layer formed on the second gate. The first interlayer insulating layer, the first gate insulating layer, and the second gate insulating layer include source contact holes and drain contact holes, and the source region and the drain region are exposed through the source contact holes and the drain contact holes, respectively.

[0051] The thin-film transistor further includes a source and a drain disposed on the same layer. Both the source and the drain are formed on the first interlayer insulating layer. The source is connected to the source region through a source contact hole, and the drain is connected to the drain region through a drain contact hole. The source and the drain can be multiple layers or a single layer formed of low-resistance materials such as Al, Ti, Mo, Cu, Ni, or their alloys, or materials with high corrosion resistance. For example, the source and the drain can be a triple layer of Ti / Cu / Ti, Ti / Ag / Ti, Ti / Al / Ti, or Mo / Al / Mo, or other single-layer or multi-layer structures.

[0052] In some embodiments, the thin-film transistor layer further includes a planarization layer located on the side of the first interlayer insulating layer away from the substrate, the planarization layer covering the source and the drain.

[0053] The light-emitting device can be disposed on the planarization layer, and the light-emitting device can be connected to the source or drain of the thin-film transistor. Specifically, the light-emitting device can be connected to the source or drain.

[0054] It is understood that the display panel includes a first electrode layer 11 and a second electrode layer 12 disposed opposite to each other, and the plurality of light-emitting devices include a plurality of light-emitting layers located between the first electrode layer 11 and the second electrode layer 12; wherein, the first electrode layer 11 may be an anode layer, and the first electrode layer 11 includes a plurality of sub-electrodes belonging to the plurality of light-emitting devices and disposed at intervals; the second electrode layer 12 may be a cathode layer and cover the entire surface, and the second electrode layer 12 is disposed close to the display surface of the display panel, that is, the plurality of light-emitting devices share the second electrode layer 12.

[0055] In this embodiment of the application, the plurality of light-emitting devices include a first light-emitting device 101 and a second light-emitting device 102, and both the first light-emitting device 101 and the second light-emitting device 102 are located on the array substrate; further, the first light-emitting device 101 includes a first sub-electrode 111 located in the first electrode layer 11, and the second light-emitting device 102 includes a second sub-electrode 112 located in the first electrode layer 11.

[0056] In some embodiments, the first light-emitting device 101 includes a first light-emitting layer 21 disposed between the first electrode layer 11 and the second electrode layer 12, and the second light-emitting device 102 includes a second light-emitting layer 22 and a third light-emitting layer 23 disposed between the first electrode layer 11 and the second electrode layer 12 and stacked thereon; wherein, the first light-emitting layer 21 is disposed between the first sub-electrode 111 and the second electrode layer 12, and the second light-emitting layer 22 and the third light-emitting layer 23 are stacked thereon between the second sub-electrode 112 and the second electrode layer 12.

[0057] In some embodiments, please refer to Figure 3 as well as Figure 4 The first light-emitting device 101 further includes a hole injection layer 31 disposed between the first sub-electrode 111 and the first light-emitting layer 21, a hole transport layer 32 disposed between the hole injection layer 31 and the first light-emitting layer 21, an electron transport layer 33 disposed between the first light-emitting layer 21 and the second electrode layer 12, and an electron injection layer 34 disposed between the electron transport layer 33 and the second electrode layer 12.

[0058] The second light-emitting device 102 further includes a hole injection layer 31 disposed between the second sub-electrode 112 and the second light-emitting layer 22, a hole transport layer 32 disposed between the hole injection layer 31 and the second light-emitting layer 22, an electron transport layer 33 disposed between the third light-emitting layer 23 and the second electrode layer 12, and an electron injection layer 34 disposed between the electron transport layer 33 and the second electrode layer 12.

[0059] It is understood that the hole injection layer 31, the hole transport layer 32, the electron transport layer 33 and the electron injection layer 34 can all be common layers, that is, film layers shared by the first light-emitting device 101 and the second light-emitting device 102.

[0060] In some embodiments, the first electrode layer 11 is an electrode for injecting holes, such as injecting holes into the hole injection layer 31, the hole transport layer 32, or the light-emitting layer. The first electrode 11 may include at least one of a conductive metal, a conductive metal oxide, or a conductive polymer. Preferably, the absolute value of the difference between the work function of the first electrode 11 and the HOMO (Highest Occupied Molecular Orbital) level or valence band level of the p-type semiconductor material in the hole injection layer 31, or the difference between the hole injection layer 31 and the HOMO (Highest Occupied Molecular Orbital) level or valence band level of the p-type semiconductor material in the hole transport layer 32 or the electron blocking layer, is less than 0.5 eV, preferably less than 0.3 eV, and more preferably less than 0.2 eV. The material of the first electrode layer 11 includes, but is not limited to, at least one of Al, Cu, Au, Ag, Mg, Fe, Co, Ni, Mn, Pd, Pt, ITO (indium tin oxide), aluminum-doped zinc oxide (AZO), or other suitable and known anode materials, which can be readily selected and used by those skilled in the art. The material of the first electrode layer 11 can be deposited using any suitable technique, such as suitable physical vapor deposition methods, including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), etc. In some embodiments, the first electrode layer 11 can be patterned, for example, patterned ITO conductive substrates are commercially available and can be used to fabricate the organic light-emitting device 10 of this application.

[0061] In some embodiments, the second electrode layer 12 is an electron-injecting electrode, such as injecting electrons into the electron injection layer 34, the electron transport layer 33, or the light-emitting layer. The second electrode layer 12 may include at least one of a conductive metal or a conductive metal oxide. Preferably, the absolute value of the difference between the work function of the second electrode layer 12 and the LUMO (Lowest Unoccupied Molecular Orbital) level or conduction band level of the n-type semiconductor material used as the electron injection layer 34, or the difference between the LUMO level or conduction band level of the n-type semiconductor material used in the electron injection layer and the electron transport layer or hole blocking layer, is less than 0.5 eV, preferably less than 0.3 eV, and more preferably less than 0.2 eV. All materials suitable for use as cathodes in light-emitting devices may be used as cathode materials in the device of this application. The material of the second electrode layer 12 includes, but is not limited to, at least one of the following: Al, Au, Ag, Ca, Ba, Mg, LiF / Al, MgAg alloy, BaF2 / Al, Cu, Fe, Co, Ni, Mn, Pd, Pt, ITO, etc. The material of the second electrode layer 12 can be deposited using any suitable technique, such as a suitable physical vapor deposition method, including radio frequency magnetron sputtering, vacuum thermal evaporation, electron beam (e-beam), etc.

[0062] In some embodiments, the hole injection layer 31 is used to facilitate the injection of holes from the first electrode layer 11 to the light-emitting layer, and the hole injection layer 31 includes a hole injection material that can receive holes injected from the positive electrode at low voltage. Preferably, the highest occupied molecular orbital (HOMO) of the hole injection material lies between the work function of the material of the first electrode layer 11 and the HOMO of the functional material of the film layer on the side of the hole injection layer 31 away from the first electrode layer 11 (e.g., the hole transport material of the hole transport layer). The hole injection material includes, but is not limited to, at least one of metalloporphyrins, oligothiophenes, arylamine-based organic materials, hexanitrile hexaazabenzophenanthrene-based organic materials, quinacridone-based organic materials, perylene-based organic materials, anthraquinones, polyaniline-based conductive polymers, and polythiophene-based conductive polymers.

[0063] In some embodiments, the hole transport layer 32 can be used to transport holes to the light-emitting layer. The hole transport layer 32 includes a hole transport material that receives holes transported from the first electrode layer 11 or the hole injection layer 31 and transfers the holes to the light-emitting layer. The hole transport material is a material with high hole mobility known in the art, and may include, but is not limited to, at least one of arylamine-based organic materials, conductive polymers, and block copolymers having both conjugated and non-conjugated portions.

[0064] In some embodiments, the electron transport layer 33 is used to transport electrons. The electron transport layer 33 includes an electron transport material that receives electrons injected from the second electrode layer 12 and transfers the electrons to the light-emitting layer. The electron transport material is a material with high electron mobility known in the art, and may include, but is not limited to, at least one of: Al complexes of 8-hydroxyquinoline, complexes containing Alq3, organic free radical compounds, hydroxyflavonoid-metal complexes, lithium 8-hydroxyquinoline (LiQ), and benzimidazole-based compounds.

[0065] In some embodiments, the electron injection layer 34 is used for injecting electrons. The electron injection layer 34 includes an electron injection material, which is preferably a material capable of transporting electrons, having the effect of injecting electrons from the negative second electrode layer 12, and having an excellent effect of injecting electrons into the light-emitting layer or light-emitting material. It also has the ability to prevent excitons generated by the light-emitting layer from migrating to the hole injection layer, and further has an excellent ability to form a thin film. The electron injection material includes, but is not limited to, at least one of lithium 8-hydroxyquinoline (LiQ), fluorenone, anthraquinone dimethane, biphenylquinone, thiamethane dioxide, pyrazole, diazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenemethane, anthrone, and their derivatives, metal complex compounds, and nitrogen-containing 5-membered ring derivatives.

[0066] In some embodiments, the first light-emitting device 101 may further include an electron blocking layer 35 disposed between the hole transport layer 32 and the first light-emitting layer 21, a hole blocking layer 36 disposed between the first light-emitting layer 21 and the electron transport layer 33, and a light extraction layer 37 disposed on the side of the second electrode 12 away from the electron injection layer 34; correspondingly, the second light-emitting device 102 may further include an electron blocking layer 35 disposed between the hole transport layer 32 and the second light-emitting layer 22, a hole blocking layer 36 disposed between the third light-emitting layer 23 and the electron transport layer 33, and a light extraction layer 37 disposed on the side of the second electrode 12 away from the electron injection layer 34.

[0067] It is understood that the electron blocking layer 35, the hole blocking layer 36, and the light extraction layer 37 are all common layers, that is, the film layers shared by the first light-emitting device 101 and the second light-emitting device 102.

[0068] In this embodiment of the application, the first light-emitting layer 21 includes a first host material and a first guest material, the second light-emitting layer 22 includes a second host material and a second guest material, and the third light-emitting layer 23 includes a third host material and a third guest material.

[0069] The first object material includes a metal complex and a fluorescent material; that is, the first light-emitting device 101 is a phosphorescent device, thus the first light-emitting device 101 has high luminous efficiency and lifespan; at the same time, the second light-emitting device 102 is provided with a stacked second light-emitting layer 22 and a third light-emitting layer 23, which effectively improves the luminous efficiency and lifespan of the second light-emitting device 102 through the dual light-emitting layers, thereby reducing the probability of display unevenness caused by the high efficiency and long lifespan of the first light-emitting device 101, improving the display uniformity of the display panel, and improving the luminous efficiency and lifespan of the display panel.

[0070] Furthermore, please combine Figure 3 , Figure 4 , Figure 5 as well as Figure 6 The direction from the first electrode layer 11 to the second electrode layer 12 is defined as the stacking direction X. The film layer between the first light-emitting layer 21 and the first electrode layer 11 is defined as the functional layer 301, and the film layer between the second light-emitting layer 22 and the first electrode layer 11 is defined as the functional layer 301. That is, the functional layer 301 may include at least one of the hole injection layer 31, the hole transport layer 32, and the electron blocking layer 35.

[0071] In the embodiments of this application, both the first light-emitting device 101 and the second light-emitting device 102 exhibit a process of change in the concentration of the guest material.

[0072] The first light-emitting layer 21 has at least one concentration partition 210 along the stacking direction X. Within the concentration partition 210, along the stacking direction X, the mass percentage of the first guest material in the first light-emitting layer 21 first increases and then decreases with the increase of the thickness of the first light-emitting layer 21.

[0073] It should be noted that the first light-emitting layer 21 can be divided into a plurality of first sub-parts arranged along the stacking direction X, and the meaning that the mass proportion of the first guest material in the first light-emitting layer 21 first increases and then decreases with the increase of the thickness of the first light-emitting layer 21 can be regarded as: within the concentration partition 210, along the stacking direction X, the mass proportion of the first guest material in each first sub-part first increases and then decreases with the increase of the distance from each first sub-part to the functional layer 301.

[0074] The second light-emitting layer 22 includes a second host material and a second object material, and the third light-emitting layer 23 includes a third host material and a third object material. The direction from the second light-emitting layer 22 to the third light-emitting layer 23 is the stacking direction X. Along the stacking direction X, the mass percentage of the second object material in the second light-emitting layer 22 increases with the increase of the thickness of the second light-emitting layer 22. Along the stacking direction X, the mass percentage of the third object material in the third light-emitting layer 23 first decreases and then increases with the increase of the thickness of the third light-emitting layer 23.

[0075] It should be noted that the second light-emitting layer 22 can be divided into multiple second sub-parts arranged along the stacking direction X, and the meaning that the mass proportion of the second guest material in the second light-emitting layer 22 increases with the increase of the thickness of the second light-emitting layer 22 can be regarded as: within the concentration partition 210, along the stacking direction X, the mass proportion of the second guest material in each second sub-part increases with the increase of the distance from each second sub-part to the functional layer 301; in addition, the third light-emitting layer 23 can be divided into multiple third sub-parts arranged along the stacking direction X, and the meaning that the mass proportion of the third guest material in the third light-emitting layer 23 first decreases and then increases with the increase of the thickness of the third light-emitting layer 23 can be regarded as: within the concentration partition 210, along the stacking direction X, the mass proportion of the third guest material in each third sub-part first decreases and then increases with the increase of the distance from each third sub-part to the second light-emitting layer 22.

[0076] As mentioned above, in this embodiment, the concentration peak of the guest material in the first light-emitting device 101 is distributed close to the functional layer 301, which will further improve the efficiency of the first light-emitting device 101, thereby making the display panel more prone to uneven display, or making the uneven display more severe. However, in this embodiment, by setting the concentration peak of the guest material in the second light-emitting device 102 before the concentration peak of the guest material in the first light-emitting device 101, the luminous efficiency between the first light-emitting device 101 and the second light-emitting device 102 can be effectively balanced.

[0077] In this process, the peak of the guest material in the second light-emitting device 102 will be located at the interface between the second light-emitting layer 22 and the third light-emitting layer 23. Therefore, in one of the concentration zones 210 near the first electrode layer 11, the thickness a of the first light-emitting layer 21 at the point where the first guest material has the maximum mass percentage is greater than or equal to the thickness b of the second light-emitting layer 22. This ensures that the concentration peak of the guest material in the second light-emitting device 102 will not appear after the concentration peak of the guest material in the first light-emitting device 101, which can effectively improve the uneven display phenomenon of the display panel caused by the high efficiency and long lifespan of the first light-emitting device 101.

[0078] In some embodiments, the first light-emitting device 101 is a green light-emitting device or a red light-emitting device, and the second light-emitting device 102 is a blue light-emitting device; thereby improving the efficiency and lifespan of the green light-emitting device and the red light-emitting device, and improving the phenomenon that the display panel turns green after reliability testing due to the high efficiency and long lifespan of the green light-emitting device (phosphorescent device).

[0079] In some embodiments, the second host material and the third host material are different; the triplet excited state (T1) of the second host material is greater than or equal to the triplet excited state (T1) of the third host material.

[0080] In some embodiments, the second host material and the third host material are selected from polycyclic aromatic hydrocarbon structures, such as naphthalene, anthracene, phenanthrene, pyrene, etc.

[0081] In some embodiments, the second guest material and the third guest material may be the same or different, and are selected from at least one of metal complexes, thermally activated delayed fluorescent materials, and fluorescent materials containing element B.

[0082] It is understandable that fluorescent materials containing element B are narrow-spectrum fluorescent materials, and the full width at half maximum (FWHM) of the emission spectrum of fluorescent materials containing element B can be less than or equal to 40 nm in order to effectively improve luminous efficiency.

[0083] In one embodiment of this application, the second guest material and the third guest material are different and selected from fluorescent materials. The horizontal molecular orientation of the third guest material is greater than that of the second guest material. The half-width at half maximum (WHM) of the emission spectrum of the third guest material is smaller than that of the emission spectrum of the second guest material. The shoulder peak of the emission spectrum of the third guest material is smaller than that of the emission spectrum of the second guest material. Since the third light-emitting layer 23 in the second light-emitting device 102 with dual light-emitting layers is located closer to the display surface of the display panel, it plays a greater role in emitting light. Therefore, this embodiment of the application can effectively improve the luminous efficiency of the second light-emitting device 102 by increasing the horizontal molecular orientation of the third guest material and decreasing the WHM and shoulder peak of the emission spectrum of the third guest material.

[0084] In another embodiment of this application, the second guest material and the third guest material are the same and selected from fluorescent materials. The horizontal molecular orientation of both the second guest material and the third guest material is greater than or equal to 80%. The half-width at half maximum (WHM) of the emission spectrum of the third guest material and the second guest material are both less than or equal to 40 nm. The percentage of shoulder height in the emission spectrum of the third guest material and the percentage of shoulder height in the emission spectrum of the second guest material are both less than or equal to 0.3. This embodiment of the application can effectively improve the luminous efficiency of the second light-emitting device 102 by increasing the horizontal molecular orientation of the second guest material and the third guest material, and decreasing the WHM and shoulder height of their emission spectra.

[0085] In another embodiment of this application, the second guest material is selected from metal complexes, or metal complexes and fluorescent materials; the third guest material is selected from fluorescent materials containing element B.

[0086] In some embodiments, the shoulder peak of the third guest material is smaller than that of the second guest material. In the organic light-emitting device 10 with a double light-emitting layer, when the guest materials of the two light-emitting layers are different, a certain energy transfer will occur, and the final emission spectrum is the superposition of the first guest material and the second guest material. Therefore, when the shoulder peak of the second guest material is lower than that of the first guest material, the final shoulder peak height of the spectrum of the organic light-emitting device will be located between the first guest material and the second guest material, which is lower than that of the first guest material. This can further reduce the energy loss of the organic light-emitting device 10 provided in this application embodiment compared with that of phosphorescent devices, so as to obtain higher device efficiency.

[0087] The absolute value of the difference between the peak value of the emission spectrum of the second guest material and the peak value of the emission spectrum of the third guest material is less than or equal to 20 nm. Since the second and third guest materials emit light simultaneously, their spectra need to be similar to reduce energy loss and improve the luminous efficiency of the second light-emitting device 102.

[0088] In some embodiments, the second host material may comprise a p-type host with hole-transporting N-type five- or six-membered rings and their derivatives, and an N-type host with triazine and its derivatives, and the third host material may comprise fused-ring aromatic hydrocarbon structures such as naphthalene, anthracene, phenanthrene, and pyrene.

[0089] In other embodiments of this application, the first light-emitting device further includes a fourth light-emitting layer stacked with the first light-emitting layer 21, and the fourth light-emitting layer and the first light-emitting layer 21 emit light of the same color; and the guest material in the fourth light-emitting layer may also contain metal complexes and fluorescent materials.

[0090] That is, the red light-emitting device and the green light-emitting device can also be dual-layer light-emitting devices, and the guest material of at least one light-emitting layer in the dual-layer light-emitting device contains metal complexes and fluorescent materials.

[0091] Continuing from the above, in the embodiments of this application, the full width at half maximum (FWHM) of the emission spectrum of the fluorescent material can be less than or equal to 40 nm, and further, it can be less than or equal to 30 nm.

[0092] In some embodiments, the metal complex described in the above embodiments may be a metal complex containing metal elements such as Ir, Pt, and Cu.

[0093] In some embodiments, the first host material, the second host material, and the third host material are selected from at least one of the following compounds:

[0094]

[0095] The first guest material, the second guest material, and the third guest material are selected from at least one of the following compounds:

[0096]

[0097] It is understandable that when the second host material and the third host material are the same, and at least a portion of the second guest material is the same as at least a portion of the third guest material, the process can be simplified, the process cost can be reduced, and mass production can be facilitated.

[0098] Furthermore, this application also provides Comparative Examples 1 to 3 and Examples 1 to 4 to verify the light-emitting device provided in this application.

[0099] In Comparative Example 1, please refer to Figure 5 and Figure 7 A contrast light-emitting device and a first light-emitting device 101 are provided, wherein the contrast light-emitting device has only a single light-emitting layer 40, the single light-emitting layer 40 containing a host material and a guest material, and the host material in the single light-emitting layer 40 is:

[0100] The quality ratio was 98.5%.

[0101] The object material in the single-layer light-emitting layer 40 is:

[0102] The quality percentage is 1.5%.

[0103] The first main material in the first light-emitting device 101 is:

[0104] The quality percentage was 92.5%.

[0105] The first object material in the first light-emitting device 101 is:

[0106] The quality percentage is 7%;

[0107] The weight percentage is 0.5%.

[0108] In Comparative Example 1, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness a of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage; in the single-layer light-emitting device, the thickness b of the single-layer light-emitting layer 40 at the location where the guest material exhibits the first peak.

[0109] For example 2, please refer to Figure 5 and Figure 6 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0110] The quality percentage was 92.5%.

[0111] The first object material in the first light-emitting device 101 is:

[0112] The quality percentage is 7%;

[0113] The weight percentage is 0.5%.

[0114] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is:

[0115] The quality ratio was 98.5%.

[0116] The second object material is:

[0117] The quality percentage is 1.5%.

[0118] In the third light-emitting layer 23, the third main material is:

[0119] The quality ratio was 98.5%.

[0120] The third object material is:

[0121] The quality percentage is 1.5%.

[0122] In Comparative Example 2, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is a; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is b.

[0123] In Example 1, please refer to Figure 5 and Figure 6 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0124] The quality percentage was 92.5%.

[0125] The first object material in the first light-emitting device 101 is:

[0126] The quality percentage is 7%;

[0127] The weight percentage is 0.5%.

[0128] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is: The quality ratio was 98.5%.

[0129] The second object material is:

[0130] The quality percentage is 1.5%.

[0131] In the third light-emitting layer 23, the third main material is:

[0132] The quality ratio was 98.5%.

[0133] The third object material is:

[0134] The quality percentage is 1.5%.

[0135] In Embodiment 1, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is a; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is b.

[0136] In Example 2, please refer to Figure 5 and Figure 6 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0137] The quality percentage was 92.5%.

[0138] The first object material in the first light-emitting device 101 is:

[0139] The quality percentage is 7%;

[0140] The weight percentage is 0.5%.

[0141] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is: The quality ratio was 98.5%.

[0142] The second object material is:

[0143] The quality percentage is 1.5%.

[0144] In the third light-emitting layer 23, the third main material is:

[0145] The quality ratio was 98.5%.

[0146] The third object material is:

[0147] The quality percentage is 1.5%.

[0148] In Embodiment 2, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is 'a'; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is 'b'.

[0149] In Example 3, please refer to Figure 5 and Figure 6 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0150] The quality percentage was 92.5%.

[0151] The first object material in the first light-emitting device 101 is:

[0152] The quality percentage is 7%;

[0153] The weight percentage is 0.5%.

[0154] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is: The quality ratio was 98.5%.

[0155] The second object material is:

[0156] The quality percentage is 1.5%.

[0157] In the third light-emitting layer 23, the third main material is:

[0158] The quality ratio was 98.5%.

[0159] The third object material is:

[0160] The quality percentage is 1.5%.

[0161] In Embodiment 3, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is 'a'; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is 'b'.

[0162] For comparison example 3, please refer to... Figure 6 and Figure 8 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0163] The quality percentage was 92.5%.

[0164] The first object material in the first light-emitting device 101 is:

[0165] The quality percentage is 7%;

[0166] The weight percentage is 0.5%.

[0167] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is: The quality ratio was 98.5%.

[0168] The second object material is:

[0169] The quality percentage is 1.5%.

[0170] In the third light-emitting layer 23, the third main material is:

[0171] The quality ratio was 98.5%.

[0172] The third object material is:

[0173] The quality percentage is 1.5%.

[0174] In Comparative Example 3, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is a; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is b.

[0175] It should be noted that in the first light-emitting device 101, the concentration distribution of the first guest material can be adjusted by controlling the parameters of the doping process to regulate the peak value and the number of peaks of the mass ratio curve of the first guest material.

[0176] In Example 4, please refer to Figure 6 and Figure 8 Provides a first light-emitting device 101 and a second light-emitting device 102, wherein the first main body material in the first light-emitting device 101 is:

[0177] The quality percentage was 92.5%.

[0178] The first object material in the first light-emitting device 101 is:

[0179] The quality percentage is 7%;

[0180] The weight percentage is 0.5%.

[0181] In the second light-emitting layer 22 of the second light-emitting device 102, the second main material is: The quality ratio was 98.5%.

[0182] The second object material is:

[0183] The quality percentage is 1.5%.

[0184] In the third light-emitting layer 23, the third main material is:

[0185] The quality ratio was 98.5%.

[0186] The third object material is:

[0187] The quality percentage is 1.5%.

[0188] In embodiment 4, in the first light-emitting device 101, in a concentration zone 210 near the first electrode layer 11, the thickness of the first light-emitting layer 21 at the location where the first guest material has the maximum mass percentage is a; in the second light-emitting device 102, the thickness of the second light-emitting layer 22 is b.

[0189] Furthermore, by adjusting the values ​​of a and b in Comparative Examples 1 to 3 and Examples 1 to 4, the device efficiency and Wy'-Wy value of the light-emitting devices in Comparative Examples 1 to 3 and Examples 1 to 4 were verified. Here, Wy'-Wy represents the change in white light color coordinates when the luminous intensity of the light-emitting device is 600 nits and it operates for 240 hours under the conditions of temperature 85℃ and humidity 85%. The thickness of the single-layer light-emitting layer 40 is 200 angstroms, the thickness of the first light-emitting layer 21 is 360 angstroms, and the sum of the thicknesses of the second light-emitting layer 22 and the third light-emitting layer 23 is 200 angstroms. The comparative light-emitting device and the second light-emitting device 102 are both blue light-emitting devices, and the first light-emitting device 101 is a green light-emitting device. The results are shown in Table 1 below.

[0190] Table 1

[0191]

[0192] As can be seen from Table 1, by controlling a to be less than or equal to b, the embodiment of this application can effectively guarantee or improve the device efficiency of the light-emitting device. At the same time, when a is less than or equal to b, the device efficiency is greater than or equal to 100%, and Wy'-Wy is less than or equal to 0.36, thereby reducing the probability of the display panel showing a greenish tint and effectively improving the device efficiency and display uniformity of the display panel.

[0193] In addition, this application embodiment also provides a display device, which includes the display panel described in the above embodiments.

[0194] In summary, in the display panel provided by the embodiments of this application, the first guest material in the first light-emitting device 101 includes a metal complex and a fluorescent material, thereby giving the first light-emitting device 101 high luminous efficiency and lifespan. Simultaneously, the second light-emitting device 102 is provided with a stacked second light-emitting layer 22 and a third light-emitting layer 23. This dual-light-emitting layer effectively improves the luminous efficiency and lifespan of the second light-emitting device 102, thereby reducing the probability of display unevenness caused by the high efficiency and long lifespan of the first light-emitting device 101, improving the display uniformity of the display panel, and enhancing the luminous efficiency and lifespan of the display panel. Furthermore... Since the peak of the guest material in the second light-emitting device 102 will be located at the interface between the second light-emitting layer 22 and the third light-emitting layer 23, in a concentration partition 210 near the first electrode layer 11, the thickness a of the first light-emitting layer 21 at the point where the first guest material has the maximum mass percentage is greater than or equal to the thickness b of the second light-emitting layer 22. This ensures that the concentration peak of the guest material in the second light-emitting device 102 will not appear after the concentration peak of the guest material in the first light-emitting device 101, which can effectively improve the uneven display phenomenon of the display panel caused by the high efficiency and long lifespan of the first light-emitting device 101.

[0195] In the description of this application, 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0196] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0197] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0198] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A display panel, characterized in that, The display panel includes a first light-emitting device and a second light-emitting device; The first light-emitting device includes a first light-emitting layer, which includes a first host material and a first guest material. The first guest material includes a metal complex and a fluorescent material. The second light-emitting device includes a second light-emitting layer and a third light-emitting layer stacked together. The second light-emitting layer and the third light-emitting layer emit light of the same color, while the first light-emitting layer and the second light-emitting layer emit light of different colors.

2. The display panel according to claim 1, characterized in that, The display panel further includes a first electrode layer and a second electrode layer disposed on opposite sides of the first light-emitting layer, and the second electrode layer is disposed close to the display surface of the display panel; The first light-emitting layer has at least one concentration partition along the stacking direction from the first electrode layer to the second electrode layer. Within the concentration partition, along the stacking direction, the mass percentage of the first guest material in the first light-emitting layer first increases and then decreases with the increase of the thickness of the first light-emitting layer.

3. The display panel according to claim 2, characterized in that, The second light-emitting layer includes a second host material and a second object material, and the third light-emitting layer includes a third host material and a third object material; The second light-emitting layer and the third light-emitting layer are stacked between the first electrode layer and the second electrode layer. The stacking direction is the direction from the second light-emitting layer to the third light-emitting layer. Along the stacking direction, the mass ratio of the second guest material in the second light-emitting layer increases with the increase of the thickness of the second light-emitting layer. Along the stacking direction, the mass percentage of the third object material in the third light-emitting layer first decreases and then increases with the increase of the thickness of the third light-emitting layer.

4. The display panel according to claim 3, characterized in that, Within a concentration zone near the first electrode layer, the thickness of the first luminescent layer at the location where the first guest material has the maximum mass percentage is greater than or equal to the thickness of the second luminescent layer.

5. The display panel according to claim 3, characterized in that, The second main material and the third main material are different.

6. The display panel according to claim 3, characterized in that, The second guest material and the third guest material may be the same or different, and are selected from at least one of metal complexes, thermally activated delayed fluorescent materials, and fluorescent materials containing element B.

7. The display panel according to claim 6, characterized in that, The second guest material is different from the third guest material and is selected from fluorescent materials, and the horizontal molecular orientation of the third guest material is greater than that of the second guest material; And / or, the full width at half maximum (FWHM) of the emission spectrum of the third guest material is smaller than that of the emission spectrum of the second guest material; And / or, the shoulder peak of the emission spectrum of the third guest material is smaller than the shoulder peak of the emission spectrum of the second guest material.

8. The display panel according to claim 6, characterized in that, The second guest material and the third guest material are the same and selected from fluorescent materials, and the horizontal molecular orientation of the second guest material and the horizontal molecular orientation of the third guest material are both greater than or equal to 80%. And / or, the full width at half maximum (FWHM) of the emission spectrum of the third guest material and the full width at half maximum (FWHM) of the emission spectrum of the second guest material are both less than or equal to 40 nm; And / or, the proportion of the shoulder height of the emission spectrum of the third guest material and the proportion of the shoulder height of the emission spectrum of the second guest material are both less than or equal to 0.

3.

9. The display panel according to claim 6, characterized in that, The second guest material is selected from metal complexes, or metal complexes and fluorescent materials; the third guest material is selected from boron-containing fluorescent materials.

10. The display panel according to claim 9, characterized in that, The shoulder peak of the emission spectrum of the third guest material is smaller than that of the shoulder peak of the emission spectrum of the second guest material, and the absolute value of the difference between the peak value of the emission spectrum of the second guest material and the peak value of the emission spectrum of the third guest material is less than or equal to 20 nm.

11. The display panel according to claim 1, characterized in that, The first light-emitting device further includes a fourth light-emitting layer stacked with the first light-emitting layer, and the fourth light-emitting layer and the first light-emitting layer emit light of the same color.

12. The display panel according to any one of claims 1 to 11, characterized in that, The first light-emitting device is a green light-emitting device or a red light-emitting device, and the second light-emitting device is a blue light-emitting device.

13. A display device, characterized in that, The display device includes a display panel as described in any one of claims 1 to 12.

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