Organic light-emitting device, display panel, and display apparatus

Abstract

The present application relates to an organic light-emitting device, a display panel, and a display apparatus. The organic light-emitting device comprises: a first electrode; a second electrode; and at least one light-emitting layer, which is located between the first electrode and the second electrode, wherein the light-emitting layer comprises a host material and at least two guest light-emitting materials, the wavelengths at luminescence spectrum peaks of the at least two guest light-emitting materials being different, and the light colors of the at least two guest light-emitting materials being of the same category. By means of doping any light-emitting layer of the organic light-emitting device in the present application with two or more guest light-emitting materials having different luminescence spectra, the intrinsic spectral characteristics of the guest light-emitting materials in the light-emitting layer can be changed, such that the luminescence spectrum of the light-emitting layer can be changed to adjust color deviation, thereby making the light-emitting layer of the organic light-emitting device satisfy predetermined color trajectory requirements in a chromaticity diagram at different angles of view.

Description

Organic light-emitting device, display panel and display device

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411004429.8, filed on July 24, 2024, entitled “Organic light-emitting device, display panel and display device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of display, in particular to an organic light-emitting device, a display panel and a display device. BACKGROUND

[0004] Organic light-emitting devices are widely used in mobile phone screens, vehicle-mounted fields and other fields due to their faster response speed, higher contrast, ultra-thinness, wide viewing angle and other characteristics. However, in actual production, the screen may appear cyan or pink phenomenon, i.e. color cast, at various viewing angles. In order to improve this situation or adjust the white light color track to meet the requirements, various methods have been tried by panel manufacturers, the most common of which is to change the microcavity structure of the device, such as thickness, transmittance, reflectivity, exciton distribution, and the film layer structure above the device, or to replace the intrinsic spectrum to improve it.

[0005] With the change of market demand, the method of relying on the intrinsic spectrum provided by the downstream or adjusting the microcavity structure cannot meet the market demand.

[0006] SUMMARY

[0007] The organic light-emitting device, the display panel and the display device provided by the embodiments of the present application can effectively improve the color cast problem.

[0008] In a first aspect, the embodiments of the present application provide an organic light-emitting device, comprising:

[0009] a first electrode;

[0010] a second electrode;

[0011] at least one light-emitting layer located between the first electrode and the second electrode; wherein the light-emitting layer comprises a host material and at least two guest light-emitting materials;

[0012] The wavelengths of the light-emitting spectrum peaks of the at least two guest light-emitting materials are different, and the at least two guest light-emitting materials are selected from the same light-emitting color.

[0013] In a second aspect, the embodiments of the present application provide a display panel, comprising:

[0014] a substrate; and

[0015] A light-emitting device layer is located on the substrate, and the light-emitting device layer comprises a plurality of light-emitting devices arranged in an array, wherein at least part of the plurality of light-emitting devices are the organic light-emitting device of the first aspect.

[0016] In a third aspect, the embodiments of the present application provide a display device comprising the display panel of the second aspect.

[0017] According to the organic light-emitting device provided by the embodiments of the present application, on the basis of the existing device structure, two or more guest light-emitting materials with different light-emitting spectra are doped in any one light-emitting layer, the intrinsic spectral characteristics of the guest light-emitting material in the light-emitting layer can be changed, and then the light-emitting spectrum of the light-emitting layer is changed, the color cast is adjusted, so that the light-emitting layer of the organic light-emitting device meets the predetermined color track requirement in the CIE1976-u'v' chromaticity diagram under different viewing angles. BRIEF DESCRIPTION OF DRAWINGS

[0018] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0019] FIG. 1 shows a structural schematic diagram of a display panel provided by the embodiments of the present application;

[0020] FIG. 2 shows a structural schematic diagram of an organic light-emitting device provided by the embodiments of the present application;

[0021] FIG. 3 shows another structural schematic diagram of an organic light-emitting device provided by the embodiments of the present application;

[0022] FIG. 4 shows a spectrum diagram (PL) of a guest material provided by the embodiments or comparative examples of the present application;

[0023] FIG. 5 shows a color point and current efficiency curve diagram of an organic light-emitting device provided by the embodiments or comparative examples of the present application

[0024] FIG. 6 shows an angle and luminance decay curve diagram of an organic light-emitting device provided by the embodiments or comparative examples of the present application

[0025] FIG. 7 shows a color track diagram of an organic light-emitting device provided by the embodiments or comparative examples of the present application at different angles from 0 to 75 degrees.

[0026] BRIEF DESCRIPTION OF DRAWINGS: 100, display panel; 101, substrate; 102, encapsulation layer; 103, adhesive film; 104, embankment insulating film; 105, passivation film; 200, organic light emitting device; 10, cathode; 9, electron injection layer; 8, electron transport layer; 7, hole blocking layer; 6, light emitting layer; 5, electron blocking layer; 4, hole transport layer; 3, hole injection layer; 2, anode; 101, substrate; 400, first organic light emitting unit; 500, charge generation layer; 600, second organic light emitting unit; 41, first hole transport layer; 42, first electron blocking layer; 43, first light emitting layer; 44, first hole blocking layer; 61, second hole transport layer; 62, second electron blocking layer; 63, second light emitting layer; 64, second hole blocking layer.

[0027] In the drawings, the same components are designated by the same reference numerals. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0028] The features and exemplary embodiments of various aspects of the present application will be described below in detail, in order to make the purposes, technical solutions and advantages of the present application more clear and apparent, the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, but not to limit the present application. The present application can be implemented without some of these specific details by those skilled in the art. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0029] The term "a plurality of", "a plurality of", "several" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of items" refers to two or more items (including two items).

[0030] Viewing angle can be understood as an angle, indicating the degree of deviation of the observer relative to the normal direction (vertical direction or light emitting direction) of the light emitting device, usually expressed in degrees (°).

[0031] It is to be noted that the relative terms such as first and second etc. are used herein only to distinguish one entity or operation from another entity or operation without necessarily requiring or implying any such actual relationship or order between such entities or operations. Also, the terms "comprises", "comprising", or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by an "includes" statement does not exclude the existence of additional elements in the process, method, article, or apparatus that includes the element.

[0032] Fig. 1 shows a structural schematic diagram of a display panel as an example.

[0033] Referring to Fig. 1, the display panel 100 comprises a substrate 101 and an encapsulation layer 102 arranged oppositely, and an organic light emitting device 200 arranged on a side of the substrate 101 facing the encapsulation layer 102, the organic light emitting device 200 comprising an anode 2, a cathode 10, and a light emitting layer 6, and the display panel 100 further comprising:

[0034] an adhesive film 103 and a passivation film 105 between the cathode 10 and the encapsulation layer 102, the passivation film 105 being arranged on a side close to the cathode 10;

[0035] a bank-shaped insulating film 104 between the anode 2 and the passivation film 105.

[0036] For example, the substrate 101 can be made of a material such as glass, or can be a flexible material, for example, made of a light-transmitting material such as polyimide (PI). A driving circuit is arranged on a side of the surface of the substrate 101, and the organic light emitting device 200 can comprise an electrode, a plurality of organic light emitting units, a charge generation layer, etc., the driving circuit being electrically connected to the organic light emitting device 200 and controlling the light emitting intensity of the organic light emitting device 200.

[0037] For example, the substrate 101 can be made of a material such as glass, or can be a flexible material, for example, made of a light-transmitting material such as polyimide (PI). A driving circuit is arranged on a side of the surface of the substrate 101, and the organic light emitting device 200 can comprise an electrode, a plurality of organic light emitting units, a charge generation layer 500, etc., the driving circuit being electrically connected to the organic light emitting device 200 and controlling the light emitting intensity of the organic light emitting device 200.

[0038] In some optional embodiments, the display panel comprises a substrate 101;

[0039] and a light emitting device layer on the substrate 101, the light emitting device layer including a plurality of light emitting devices arranged in an array, wherein at least some of the plurality of light emitting devices are organic light emitting devices 200.

[0040] The light emitting layer 6 is disposed on the anode 2. In an exemplary embodiment, other layer structures can also be disposed between the light emitting layer 6 and the anode 2 or the cathode 10. Alternatively, the other layer structures can be any one or more of a hole injection layer 3 (HIL), a hole transport layer 4 (HTL), an electron blocking layer 5 (EBL), an EML, a hole blocking layer 7 (HBL), an electron transport layer 8 (ETL), and / or an electron injection layer 9 (EIL).

[0041] It can be understood that the substrate 101 defines a plurality of pixel regions, such as red pixel regions, green pixel regions, and blue pixel regions. The organic light emitting devices 200 are located in each pixel region. In other words, any one of the organic light emitting devices 200 that emits red, green, or blue light is correspondingly located in the red pixel region, the green pixel region, and the blue pixel region. A plurality of pixel blocks, i.e., the positions of the corresponding pixel regions, can be observed in a top view of the display panel including a plurality of organic light emitting devices 200. The plurality of closely arranged pixel blocks are arranged on the display panel and can be mixed to form white light or light of other colors.

[0042] Any one of the organic light emitting devices 200 can include a plurality of light emitting layers 6 of the same color or a plurality of light emitting layers 6 of different colors, respectively. When at least one light emitting layer 6 emits light of the same color, a single light emitting color organic light emitting device 200 can be obtained, such as a single blue, green, red, etc. When at least one light emitting layer 6 in any one of the organic light emitting devices 200 emits light of different colors, the light emitting colors of the at least one light emitting layer 6 belong to the same color system, such as a blue system, a green system, a red system, etc. The light emitting layers 6 can emit white light or light of other colors by mixing the different colors of light emitted.

[0043] The organic light emitting device 200 is a top emission type device that emits light emitted by the at least one light emitting layer 6 in a bottom direction, but the organic light emitting device 200 according to the embodiments of the present application is not limited to the above example and can be a bottom emission type or a dual emission type.

[0044] FIG. 2 shows a structural schematic diagram of the organic light emitting device 200 according to an embodiment of the present application.

[0045] As shown in FIG. 2, the organic light emitting device 200 can include a cathode 10, an electron injection layer 9, an electron transport layer 8, a hole blocking layer 7, a light emitting layer 6, an electron blocking layer 5, a hole transport layer 4, a hole injection layer 3, and an anode 2.

[0046] In some alternative embodiments, the anode 2 material used in the anode 2 can include metals (e.g., copper, gold, silver, iron, chromium, nickel, manganese, palladium, platinum, etc. and alloys thereof), metal oxides (e.g., indium oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc.), conductive polymers (e.g., polyaniline, polypyrrole, poly(3-methylthiophene), etc.). In addition to the above materials and combinations thereof, other known materials suitable for use as the anode 2 can also be included.

[0047] In some alternative embodiments, the cathode 10 can include metal materials such as aluminum, magnesium, silver, indium, tin, titanium, etc. and alloys thereof. The cathode 10 can include a multi-layer cathode 10 composed of layers of one or several of metal oxides and metal halides (e.g., LiF / Al, LiO2 / Al, BaF2 / Al, etc.). In addition to the above materials and combinations thereof, other known materials suitable for use as the cathode 10 can also be included.

[0048] In some alternative embodiments, an optical coupling layer can be provided on the side of the cathode 10 facing away from the anode 2, which can be made of transparent conductive oxides or organic materials such as indium tin oxide (ITO), etc., which can improve light extraction efficiency.

[0049] In some embodiments, the hole injection layer 3 material includes a hole transport material and a P-type doping material.

[0050] In some embodiments, the P-type doping material is selected from, but not limited to, F4TCNQ (hexadecafluorotetracyanoquinodimethane), NDP-9 (2,3,5,6-tetramethyl-N-methyl pyrrolo[3,2-b]pyrrolo[2',3':5,6]tetrazine-1,4-diamine), or transition metal compounds such as FeCl3, MoO3, WO3, etc.

[0051] In some embodiments, the hole transport material includes, but is not limited to, polystyrene (PPV) and its derivatives, anthracene derivatives, fullerene and its derivatives.

[0052] In some embodiments, the hole transport layer 4 (HTL), the hole blocking layer 7 (HBL), the electron transport layer 8 (ETL), and the electron blocking layer 5 can each be independently selected from the corresponding materials known in the art. For example, hole transport materials (HTM), hole blocking materials (HBM), electron transport materials (ETM), etc.

[0053] As examples, the hole injection material, the hole transport material, and the electron transport material can be selected from 2,2"-dimethyl-N,N"-di-1-naphthyl-N,N"-diphenyl[1,1"-biphenyl]-4,4"-diamine (a-NPD), 4,4",4-tris(carbazol-9-yl)triphenylamine (TCTA), 1,3-bis(carbazol-9-yl)benzene (mCP), 4,4"-bis(9-carbazol) biphenyl (CBP), 3,3"-di(N-carbazolyl)-1,1"-biphenyl (mCBP), N,N-bisbiphenyl-4"-(9H-carbazolyl)biphenyl-4-amine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), 4,4"-cyclohexylbisN,N-di(4-methylphenyl)aniline (TAPC), N,N"-diphenyl-N,N"-(1-naphthyl)-1,1"-biphenyl-4,4"-diamine (a-NPB), N,N"-di(naphthalen-2-yl)-N,N"-diphenylbiphenyl-4,4"-diamine (NPB), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), polyvinylcarbazole (PVK), 9-phenyl-3,9-biscarbazole (CCP), molybdenum trioxide (MoO3), and the like, but are not limited to the above materials.

[0054] As examples, the hole injection material, the hole transport material, and the electron transport material can be selected from 2,2"-dimethyl-N,N"-di-1-naphthyl-N,N"-diphenyl[1,1"-biphenyl]-4,4"-diamine (a-NPD), 4,4",4-tris(carbazol-9-yl)triphenylamine (TCTA), 1,3-bis(carbazol-9-yl)benzene (mCP), 4,4"-bis(9-carbazol) biphenyl (CBP), 3,3"-di(N-carbazolyl)-1,1"-biphenyl (mCBP), N,N-bisbiphenyl-4"-(9H-carbazolyl)biphenyl-4-amine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), 4,4"-cyclohexylbisN,N-di(4-methylphenyl)aniline (TAPC), N,N"-diphenyl-N,N"-(1-naphthyl)-1,1"-biphenyl-4,4"-diamine (a-NPB), N,N"-di(naphthalen-2-yl)-N,N"-diphenylbiphenyl-4,4"-diamine (NPB), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), polyvinylcarbazole (PVK), 9-phenyl-3,9-biscarbazole (CCP), molybdenum trioxide (MoO3), and the like, but are not limited to the above materials.

[0055] The main function of the electron blocking layer 5 (EBL) is to prevent electron injection or migration out of the light-emitting layer 6 to improve the light-emitting efficiency and stability of the device. The material of the electron blocking layer 5 can be 4,4'-bis(N-carbazolyl)biphenyl (CBP), 1,3,5-tris(4-phenylbenzimidazol-1-yl)benzene (TPBi), tris(4-methylphenyl)amine (TCTA), and 4,4'-cyclohexylbis(4-phenylpyridine) (CDBP), and the like.

[0056] The light-emitting layer 6 is the core part of the organic light-emitting device 200, and its performance directly determines the light-emitting efficiency, color and stability of the device. Generally, the light-emitting layer 6 can contain a host material and a guest light-emitting material.

[0057] The host material generally refers to a material commonly used in the light-emitting layer 6, and the host material can exist together with the guest light-emitting material in the light-emitting layer 6 to emit light. The host material exhibits light-emitting characteristics under certain conditions, and has a light-emitting spectrum and an absorption spectrum. The host material can be selected as a bipolar host material. The host material can transport electrons and holes (holes can be understood as positive charge equivalents of electrons) at the same time, and these materials can effectively improve the efficiency and stability of the device. As an example, the host material can be CBP (4,4'-N,N'-dicarbazole-biphenyl), TPBi, (2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)).

[0058] The guest light-emitting material refers to a light-emitting molecule doped into the host material, and is mainly used in the light-emitting layer 6 (EML). The guest light-emitting material is doped into the host material to adjust the light-emitting color and improve the light-emitting efficiency. In some optional embodiments, the guest light-emitting material can include at least one of an organic dye, a fluorescent material and a phosphorescent material. Generally, in the same light-emitting layer, the guest light-emitting material in any one light-emitting layer is selected from any one of an organic dye, a fluorescent material and a phosphorescent material. In the same organic light-emitting device 200, the guest light-emitting material in the light-emitting layer is selected from any one of an organic dye, a fluorescent material and a phosphorescent material. As an example, the fluorescent material is, for example, an aluminum complex (Alq3), a carbazole derivative (CBP), a polyfluorene (PFO), a polystyrene (PBD). As an example, the guest light-emitting material can be a green phosphorescent light-emitting material (Ir(ppy)3) and a blue phosphorescent light-emitting material FIrpic.

[0059] Generally, one host material and one guest light-emitting material are usually added in any one light-emitting layer 6 to realize light emission. However, in actual production, the market has higher and higher requirements for the color track of the display panel under multiple viewing angles. That is, the display panel, commonly known as the screen, may appear blue or pink under multiple viewing angles, that is, color cast. In order to improve this situation or adjust the light color track to meet the requirements, various methods have been tried, and the most common one is to change the device microcavity structure, such as thickness, transmittance, reflectivity, exciton distribution, etc., or replace the guest light-emitting material to improve the intrinsic spectrum.

[0060] The microcavity structure of the organic light emitting device 200 is a design method for regulating the distribution and emission characteristics of light by introducing an optical cavity in the device. The microcavity structure is usually composed of a mirror (such as a metal or a distributed Bragg reflector, DBR) and a light emitting layer 6. As an example, the device microcavity structure can include a bottom mirror with high reflectivity and a top mirror with partial reflectivity. As another example, the device microcavity structure can include a distributed Bragg reflector composed of multiple alternating layers of high and low refractive index materials.

[0061] With the change of market demand, the way of relying on the intrinsic emission spectrum of the object light emitting material provided by the downstream or adjusting the microcavity structure cannot meet the market demand. In addition, the development of new object light emitting materials is slow, and has entered a bottleneck period and is difficult to meet the market demand of light color trajectory.

[0062] In view of this, the present application provides an organic light emitting device 200 to solve the above color deviation problem.

[0063] In a first aspect, the embodiments of the present application provide an organic light emitting device 200, comprising:

[0064] a first electrode;

[0065] a second electrode;

[0066] at least one light emitting layer 6 located between the first electrode and the second electrode; wherein the light emitting layer 6 comprises a host material and at least two object light emitting materials.

[0067] The emission spectrum peaks of the at least two object light emitting materials are different in wavelength, and the at least two object light emitting materials are selected from the same light emitting color.

[0068] The first electrode or the second electrode can be an anode 2 arbitrarily. When the first electrode is an anode 2, the second electrode is a cathode 10 accordingly.

[0069] It is found through research that doping at least two object light emitting materials (double object light emitting material doping) in the host material in the light emitting layer 6 changes the emission spectrum of the light emitting layer 6, changes the chromaticity coordinates and brightness of the light emitting layer 6 in the CIE1976-u’v’ chromaticity diagram, and changes the color points (CIE) and brightness under different viewing angles by synthesizing white light or other color light with other light, adjusts the color deviation under each viewing angle, and further adjusts different white light color trajectories to meet the development requirements, so that the light emitting layer 6 of the organic light emitting device 200 meets the predetermined color trajectory requirements in the CIE1976-u’v’ chromaticity diagram under different viewing angles, to avoid the phenomenon of emitting blue or pink under each viewing angle of the organic light emitting device 200.

[0070] It can be understood that the color and the emission spectrum of the light-emitting layer 6 are determined by at least two guest light-emitting materials in the light-emitting layer 6. The intrinsic spectrum of the light-emitting layer 6 can be changed by doping the host material with at least two guest light-emitting materials, the emission spectrum of the layer can be adjusted, the color cast can be adjusted, so that the color system of the organic light-emitting device 200 under different viewing angles meets the predetermined color system requirements.

[0071] As an example, the CIE1976-u'v' chromaticity diagram includes four quadrants, the first quadrant is in the upper right, and the third quadrant is in the lower left; regarding the third quadrant as an angle, the angle bisector divides the third quadrant into a first angle close to the second quadrant and a second angle close to the fourth quadrant; the light-emitting layer 6 containing the host material and a specific guest light-emitting material is in the third quadrant in the second angle under a viewing angle of 0 to 30 degrees, and is in the third quadrant in the second angle under a viewing angle of 60 to 75 degrees; by adding an additional different specific guest light-emitting material, the light-emitting layer 6 can be in the third quadrant in the first angle under a viewing angle of 0 to 30 degrees, and the trajectory is shifted to the second quadrant and changes; while in the third quadrant in the second angle under a viewing angle of 60 to 75 degrees, the trajectory is basically unchanged.

[0072] In some optional embodiments, a plurality of organic light-emitting devices 200 includes a plurality of light-emitting layers 6 perpendicular to the light-emitting direction, and the plurality of light-emitting layers 6 (EML) can each include an EML of the same color or respectively include an EML of different colors. By mixing the light emitted from the plurality of light-emitting layers 6, white light or light of other colors can be achieved, and by adding at least two guest light-emitting materials in the light-emitting layer 6, the chromaticity trajectory of the white light under different viewing angles can be adjusted.

[0073] In some optional embodiments, the at least two guest light-emitting materials include a first guest light-emitting material and a second guest light-emitting material; the wavelength difference between the emission spectrum peak of the first guest light-emitting material and the emission spectrum peak of the second guest light-emitting material is X, wherein 1 nm≤X≤30 nm.

[0074] Optionally, the wavelength difference X can be any value or a range consisting of any of 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm.

[0075] In this embodiment, the wavelength difference X between the emission spectral peaks of the first and second guest light-emitting materials is within the aforementioned range, ensuring that the emitted light has a similar color. This is crucial for the purity and consistency of the color of the light-emitting layer 6, allowing adjustment of the color system of light at different angles, while also considering current efficiency and light attenuation, thus improving the display effect and adjusting color deviation. The wavelength difference X being within the aforementioned range also results in higher energy transfer efficiency in the organic light-emitting device 200, thereby improving luminous efficiency. Furthermore, it reduces light loss due to absorption and scattering during interlayer propagation, thereby improving the brightness and efficiency of the device.

[0076] Furthermore, when the organic light-emitting device 200 is used for a long time or under high current density, the wavelength difference X between the guest light-emitting materials in the light-emitting layer 6 containing the above-mentioned materials is within the above-mentioned range, which can reduce the color change caused by the degradation of a certain guest light-emitting material. The first guest light-emitting material and the second guest light-emitting material have similar degradation cycles, thereby maintaining a stable color performance over a long period of time and avoiding color deviation.

[0077] In some optional embodiments, the at least two guest luminescent materials include a first guest luminescent material and a second guest luminescent material; the difference between the half-width at half maximum (FWHM) of the first guest luminescent material and the second guest luminescent material is 1 nm ≤ x ≤ 30 nm. Optionally, the difference between the FWHM of the first guest luminescent material and the second guest luminescent material can be any value or a range thereof selected from 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, and 30 nm.

[0078] In this embodiment, the first guest luminescent material and the second guest luminescent material have relatively narrow emission spectra, and the difference between them is within the above-mentioned range, which can ensure the color purity and consistency of the emission.

[0079] As an example, the first guest luminescent material can be the blue phosphorescent material Firpic (bis(4,6-difluorophenylpyridine-N,C2)pyridinecarboxyiridium). The second guest luminescent material can be the blue phosphorescent material FirN4, namely (OC-6-44)-bis[3,5-difluoro-2-(2-pyridyl)phenyl][2-(2H-tetrazole-5-yl)pyridine]iridium.

[0080] In some optional embodiments, the mass ratio of the first guest luminescent material to the second guest luminescent material is (1:9) to (9:1). Optionally, the mass ratio of the first guest luminescent material to the second guest luminescent material can be any value or a range of combinations thereof from 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 2:3, 3:4, 4:5, 5:6, 6:7, 7:8, 8:9, 1:1, 9:8, 8:7, 7:6, 6:5, 5:4, 4:3, 3:2, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1.

[0081] The mass ratio of the first guest light-emitting material to the second guest light-emitting material in the light-emitting layer 6 is within the above range, which further changes the intrinsic spectrum of the light-emitting layer 6, adjusts the emission spectrum of this layer, further adjusts the color shift, and avoids the organic light-emitting device 200 from appearing bluish or pinkish at various viewing angles.

[0082] The content of at least two guest luminescent materials in the luminescent layer 6 can be appropriately doped according to factors such as the color type, material, and luminous intensity of the material in the luminescent layer 6, thereby adjusting the luminous color, luminous intensity, and luminous efficiency. In some optional embodiments, based on the total mass of the luminescent layer 6, the mass fraction of the at least two guest luminescent materials is 1% to 30%.

[0083] Optionally, the mass fraction of at least two guest luminescent materials is any value or range of a combination thereof from 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%.

[0084] In some optional embodiments, the organic light-emitting device 200 includes the following structures stacked in sequence: a first carrier injection layer located near the first electrode; a first carrier transport layer; a second carrier blocking layer; the light-emitting layer 6; the first carrier blocking layer; the second carrier transport layer; and the second carrier injection layer located near the second electrode.

[0085] In this embodiment, the first carrier injection layer can be understood as the electron injection layer 9; the first carrier transport layer can be understood as the electron transport layer 8; the second carrier blocking layer can be understood as the hole blocking layer 7; the first carrier blocking layer can be understood as the electron blocking layer 5; the second carrier transport layer can be understood as the hole transport layer 4; the second carrier injection layer can be understood as the hole injection layer 3; the first electrode can be the cathode 10, and the second electrode can be the anode 2.

[0086] When there are multiple light-emitting layers 6 in an organic light-emitting device 200, any one of the light-emitting layers 6 may include a host material and at least two guest light-emitting materials, thereby improving the color shift of the organic light-emitting device 200.

[0087] Accordingly, the organic light-emitting device 200 further includes a charge-generating layer; the at least one light-emitting layer 6 includes a first light-emitting layer 43 and a second light-emitting layer 63; the charge-generating layer is located between the first light-emitting layer 43 and the second light-emitting layer 63.

[0088] In some optional embodiments, the organic light-emitting device 200 includes the following structures stacked in sequence: a third electron injection layer 9 located near the first electrode; a third electron transport layer 8; a third hole blocking layer 7; a second light-emitting layer 63; a third electron blocking layer 5; a third hole transport layer 4; the charge generation layer; a fourth hole blocking layer 7; the first light-emitting layer 43; a fourth electron blocking layer 5; a fourth hole transport layer 4; and a fourth hole injection layer 3 located near the second electrode.

[0089] Figure 3 shows another structural schematic diagram of the organic light-emitting device 200 according to an embodiment of this application.

[0090] As shown in Figure 3, the organic light-emitting device 200 includes a cathode 10, a second organic light-emitting unit 600, a charge generation layer 500 (CGL), a first organic light-emitting unit 400, an anode 2, and a substrate 101, stacked sequentially. The second organic light-emitting unit 600 includes an electron injection layer 9 (EIL), an electron transport layer 8 (ET), a second hole blocking layer 64 (HBL2), a second light-emitting layer 63 (EML2), a second electron blocking layer 62, and a second hole transport layer 61 (HTL2). The first organic light-emitting unit 400 includes a first hole blocking layer 44 (HBL1), a first light-emitting layer 43 (EML1), a first electron blocking layer 42 (Prime1), a first hole transport layer 41 (HTL1), and a first hole injection layer 33 (HIL1).

[0091] Generally, the charge generation layer 500 includes an N-type charge generation layer 500 and a P-type charge generation layer 500.

[0092] The layer structures in the first organic light-emitting unit 400 and the second organic light-emitting unit 600 can be reasonably configured according to requirements, such as adjusting the thickness of any layer or removing any layer. For example, the thicknesses of the electron injection layer 9 (EIL), electron transport layer 8, second hole blocking layer 64 (HBL2), second light-emitting layer 63 (EML2), second electron blocking layer 62, second hole transport layer 61 (HTL2), first hole blocking layer 44 (HBL1), first light-emitting layer 43 (EML1), first electron blocking layer 42 (Prime1), first hole transport layer 41 (HTL1), and first hole injection layer 33 (HIL1) are all easily achievable and will not be elaborated here.

[0093] In some alternative implementations, the same luminescent color includes any one of red, green, and blue.

[0094] Accordingly, the light-emitting layer 6 includes any one of the following: red light-emitting layer 6, green light-emitting layer 6, and blue light-emitting layer 6.

[0095] It is understood that the doping methods of the above-mentioned at least two guest light-emitting materials applied to the above-mentioned light-emitting layer 6 can be applied to the adjustment of any color system, and a light-emitting layer 6 can present any color system: red, green, or blue.

[0096] In some optional embodiments, the first light-emitting layer 43 and the second light-emitting layer 63 emit the same light color.

[0097] For example, at least one light-emitting layer 6 includes a first light-emitting layer 43 and a second light-emitting layer 63. The first light-emitting layer 43 includes at least two types of guest light-emitting materials; the second light-emitting layer 63 includes at least two types of guest light-emitting materials. The aforementioned guest light-emitting materials belong to the same color or all belong to the same color system. Any color can be red, green, blue, etc.

[0098] In some alternative embodiments, in order to adjust the color shift and change the intrinsic spectrum of the guest luminescent material, the at least one luminescent layer 6 includes a red luminescent layer 6, which includes at least two red-based third guest luminescent materials, and the at least two third guest luminescent materials have different wavelengths of their emission spectral peaks.

[0099] In some alternative embodiments, in order to adjust the color shift and change the intrinsic spectrum of the guest luminescent material, the at least one luminescent layer 6 includes a green luminescent layer 6, which includes at least two green-based fourth guest luminescent materials, and the at least two fourth guest luminescent materials have different wavelengths of their emission spectral peaks.

[0100] In some optional embodiments, to adjust the color shift and change the intrinsic spectrum of the guest luminescent material, the at least one luminescent layer 6 includes a blue luminescent layer 6 comprising at least two blue-based fifth guest luminescent materials, wherein the emission spectral peaks of the at least two fifth guest luminescent materials have different wavelengths. For example, the at least two blue-based fifth guest luminescent materials are BD1 and BD2, and their structural formulas are shown below:

[0101] Two blue light-emitting guest materials, BD1 and BD2, were simulated and synthesized separately, as well as by combining BD1 and BD2 at mass ratios of 1:9, 5:5, and 9:1. The resulting photoluminescence (PL) spectra are shown in Figure 4. The figure shows that the normalized PL spectra of these materials all fall between those of BD1 and BD2. Furthermore, the figure reveals that the higher the mass percentage of BD1, the closer the synthesized PL spectrum is to the original PL spectrum of BD1.

[0102] Using the SETFOS (semiconducting thin film optics simulation software) software, the structure of the organic light-emitting device according to an embodiment of this application is shown in Figure 3. The guest materials selected are BD1 and / or BD2. By setting the mass ratio of the host material to the two guest materials to 49:1, and setting different mass ratios for the two guest materials (1:9, 5:5, and 1:1), the color point versus current efficiency curves are obtained, as shown in Figure 5. The color point represents the color of the light emitted by the light-emitting device under specific operating conditions (such as a specific current density or voltage). Color points are usually represented on a chromaticity diagram (such as the CIE 1976 chromaticity diagram), with the precise position of the color represented by u'v' coordinates. Each color point in the figure typically corresponds to the emission color and current efficiency under the operating current density condition of J10.

[0103] As shown in Figure 5, due to the appropriate selection of BD1 and BD2 materials, when doped in the luminescent layer at different mass ratios, the color point and current efficiency fall between those of BD1 and BD2 alone, exhibiting comparable current efficiency. When BD1 and BD2 are mixed, the optimal efficiency gradually shifts towards BD1 as the mass proportion of BD1 increases. This demonstrates that the luminescent layer can be prepared using at least two guest luminescent materials.

[0104] Using the Setfos (semiconducting thin film optics simulation software) software, the structure of the organic light-emitting device according to an embodiment of this application is shown in Figure 3. The guest materials selected are BD1 and / or BD2. By setting the mass ratio of the host material to the two guest materials to 49:1, and setting different mass ratios for the two guest materials (1:9, 5:5, and 1:1), angle versus brightness attenuation curves are obtained, as shown in Figure 6. Brightness is the intensity of light emitted or reflected per unit area, usually expressed as candela per square meter (cd / m²). In the angle versus brightness attenuation curve, brightness is typically the relative light intensity measured at different angles. The rate of brightness attenuation with angle is an important indicator of the device's viewing angle performance. A slower attenuation rate indicates a wider viewing angle range and better viewing angle performance.

[0105] As shown in Figure 6, due to the appropriate selection of BD1 and BD2 materials, and their doping in the luminescent layer at different mass ratios, the brightness attenuation at different angles falls between that of BD1 alone and BD2 alone, exhibiting a comparable brightness attenuation effect. This demonstrates that the luminescent layer can be prepared using at least two guest luminescent materials.

[0106] Using the SETFOS (semiconducting thin film optics simulation software) software, the structure of the organic light-emitting device according to an embodiment of this application is shown in Figure 3. The guest materials selected are BD1 and / or BD2. By setting the mass ratio of the host material to the two guest materials to 49:1, and setting different mass ratios for the two guest materials (1:9, 5:5, and 1:1), the CIE 1976 u'v' diagram, i.e., Figure 7, is obtained. Figure 7 shows the color track diagrams of the light-emitting layer of the organic light-emitting device using the above two guest light-emitting materials at different angles from 0 to 75 degrees. In Figure 7, the origin in the circle represents the baseline value of color accuracy (JNCD, just notice color difference), with a baseline value of 0 representing the best color accuracy. The circles in the figure represent color deviation intensity; the color deviation intensity of the circle closest to the origin is 2.5, and the color deviation intensity of the outermost circle is 6. The points near the circles in the color tracks for multiple material types represent the color deviation at a 0-degree viewing angle. Each color track has 6 points, corresponding to viewing angles from 0 to 75 degrees. The point furthest from the origin along the color track represents the chromaticity at 75 degrees. As shown in the diagram, BD1 and BD2, doped at a certain mass ratio, improve the chromaticity of a single BD1 or BD2 material at a specific angle, thus adjusting the color cast. Based on the BD1 color track, with a fixed 45-degree white light point and brightness decay, as the proportion of BD1 decreases, the large viewing angle (approximately 45 to 75 degrees) gradually shifts towards blue, while the small viewing angle (approximately 0 to 30 degrees) gradually shifts towards the upper left, optimizing the shift towards red at small viewing angles and towards green at large viewing angles.

[0107] In summary, by adding at least two guest light-emitting materials to the main material in the light layer, the color deviation of organic light-emitting devices can be adjusted. Based on the limited guest light-emitting materials and the improvement of the microcavity structure, the color deviation of organic light-emitting devices can be further adjusted according to customer requirements, so as to meet the market's requirements for the purity of color and appropriate brightness of display panels at different angles.

[0108] In some optional embodiments, to adjust the color shift and change the intrinsic spectrum of the guest luminescent material, the at least one luminescent layer 6 includes a blue luminescent layer 6. The blue luminescent layer 6 includes three blue-based fifth guest luminescent materials, namely BD1, BD2, and BD3, with different wavelengths of their emission spectral peaks. The structural formula of BD3 is shown below:

[0109] It should be noted that the display device provided in this application embodiment has the beneficial effects of the display panel or organic light-emitting layer in any of the foregoing embodiments. For details on the beneficial effects of the display device, please refer to the foregoing description of the display panel; these will not be repeated in this application embodiment.

[0110] Examples of display devices include, but are not limited to, mobile phones, computers, televisions, smartwatches, smart cars, VR or AR headsets, etc., and this application does not specifically limit them.

[0111] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An organic light emitting device, wherein, The organic light-emitting device comprises: a first electrode; a second electrode; at least one light-emitting layer between the first electrode and the second electrode; wherein the light-emitting layer comprises a host material and at least two guest light-emitting materials; the light-emitting spectrum peaks of the at least two guest light-emitting materials are different in wavelength, and the at least two guest light-emitting materials are selected from the same light-emitting color.

2. The organic light-emitting device according to claim 1, wherein The at least two guest light-emitting materials comprise a first guest light-emitting material and a second guest light-emitting material; the difference between the light-emitting spectrum peak wavelength of the first guest light-emitting material and the light-emitting spectrum peak wavelength of the second guest light-emitting material is X, wherein 1 nm≤X≤30 nm.

3. The organic light emitting device according to claim 1, wherein, the difference between the half-wave width of the first guest light-emitting material and the half-wave width of the second guest light-emitting material is 1 nm≤X≤20 nm.

4. The organic light-emitting device according to claim 1, wherein, the mass ratio of the first guest light-emitting material to the second guest light-emitting material is (1:9)~(9:1).

5. The organic light emitting device according to claim 1, wherein, the mass fraction of the at least two guest light-emitting materials is 1%~30% based on the total mass of the light-emitting layer.

6. The organic light emitting device according to claim 1, wherein, The organic light-emitting device comprises, in sequence: a first carrier injection layer on the side close to the first electrode; a first carrier transport layer; a second carrier blocking layer; the light-emitting layer; a first carrier blocking layer; a second carrier transport layer; a second carrier injection layer on the side close to the second electrode.

7. The organic light emitting device according to claim 1, wherein, The at least two guest light-emitting materials are selected from at least one of organic dyes, fluorescent materials and phosphorescent materials.

8. An organic light-emitting device according to any one of claims 1 to 7, wherein, The organic light-emitting device further comprises a charge generation layer; the at least one light-emitting layer comprises a first light-emitting layer and a second light-emitting layer; the charge generation layer is between the first light-emitting layer and the second light-emitting layer.

9. The organic light emitting device of claim 8, wherein, The light-emitting colors of the first light-emitting layer and the second light-emitting layer are the same light-emitting color.

10. The organic light emitting device according to claim 8, wherein, The organic light-emitting device comprises, in sequence: a third electron injection layer on the side close to the first electrode; a third electron transport layer; a third hole blocking layer; the second light-emitting layer; a third electron blocking layer; a third hole transport layer; the charge generation layer; a fourth hole blocking layer; the first light-emitting layer; a fourth electron blocking layer; a fourth hole transport layer; a fourth hole injection layer on the side close to the second electrode.

11. The organic light emitting device according to claim 1, wherein, The same light-emitting color comprises any one of red, green and blue.

12. The organic light emitting device of claim 11, wherein, The at least one light-emitting layer comprises any one of a red light-emitting layer, a green light-emitting layer and a blue light-emitting layer; the at least one light-emitting layer satisfies any one of the following conditions: 1) the red light-emitting layer comprises at least two red third guest light-emitting materials, and the light-emitting spectrum peaks of the at least two third guest light-emitting materials are different in wavelength; 2) the green light-emitting layer comprises at least two green fourth guest light-emitting materials, and the light-emitting spectrum peaks of the at least two fourth guest light-emitting materials are different in wavelength; 3) the blue light-emitting layer comprises at least two blue fifth guest light-emitting materials, and the light-emitting spectrum peaks of the at least two fifth guest light-emitting materials are different in wavelength.

13. A display panel, wherein, The organic light-emitting device comprises: a substrate; and a light-emitting device layer on the substrate, the light-emitting device layer comprising a plurality of light-emitting devices arranged in an array, wherein at least part of the plurality of light-emitting devices are the organic light-emitting device according to any one of claims 1 to 12.

14. A display device, wherein, The display panel of claim 13 is included.

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