OLED element, display substrate and display device

Abstract

The invention discloses an OLED element, a display substrate and a display device. The OLED element comprises an anode, an organic light-emitting layer and a cathode which are sequentially stacked, the organic light-emitting layer comprises a light-emitting layer and an exciton modulation layer, and the exciton modulation layer makes contact with the light-emitting layer and is located on the side, close to or away from the anode, of the light-emitting layer; the light-emitting layer comprises a first host material, a second host material and a guest material; the exciton modulation layer comprises a first host material and a second host material, and the mixing ratio of the first host material to the second host material is greater than or equal to 10: 1 and less than or equal to 1: 1.

Description

Technical Field

[0001] This article relates to but is not limited to the field of display technology, and in particular to an OLED element, a display substrate, and a display device. Background Art

[0002] Organic light-emitting diodes (OLEDs) are active light-emitting display devices with advantages such as self-luminescence, wide viewing angles, high contrast, low power consumption, and extremely fast response times. With the continuous advancement of display technology, displays using OLEDs as light-emitting elements and thin-film transistors (TFTs) for signal control have become mainstream products in the display field.

[0003] OLED includes an anode, a cathode, and a light-emitting layer arranged between the anode and the cathode. Its light-emitting principle is that the anode injects holes into the light-emitting layer and the cathode injects electrons into the light-emitting layer. When the electrons and holes meet in the light-emitting layer, excitons are generated. After the electrons and holes in the excitons recombine, they transfer energy to the light-emitting layer. The light-emitting material in the light-emitting layer emits light through a radiation relaxation process. Summary of the Invention

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] Embodiments of the present disclosure provide an OLED element, a display substrate, and a display device.

[0006] In a first aspect, an embodiment of the present disclosure provides an OLED element, comprising: an anode, an organic light-emitting layer, and a cathode stacked in sequence, the organic light-emitting layer comprising a light-emitting layer and an exciton modulation layer, the exciton modulation layer being in contact with the light-emitting layer and being located on a side of the light-emitting layer close to or away from the anode; the light-emitting layer comprising a first host material, a second host material, and a guest material; the exciton modulation layer comprising the first host material and the second host material, the mixing ratio of the first host material and the second host material being greater than or equal to 10:1 and less than or equal to 1:1.

[0007] In an exemplary embodiment, the light-emitting layer includes any one of a blue light-emitting layer, a red light-emitting layer and a green light-emitting layer.

[0008] In an exemplary embodiment, in a direction away from the anode, the OLED element includes at least two stacked light-emitting layers of the same color.

[0009] In an exemplary embodiment, the light-emitting layer includes three color light-emitting layers arranged in sequence away from the anode, and the three color light-emitting layers include a blue light-emitting layer, a red light-emitting layer and a green light-emitting layer; the exciton modulation layer is arranged at least corresponding to the blue light-emitting layer.

[0010] In an exemplary embodiment, the first body material includes a P-type body material, and the second body material includes an N-type body material.

[0011] In an exemplary embodiment, in the blue light-emitting layer, the P-type host material includes a compound having the following structural formula: ; wherein the molecular mass of R1 is between 70 and 260; R1 is independently selected from a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamine group having 6 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 1 ...oxy group having 1 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl groups having 3 to 39 carbon atoms, substituted or unsubstituted heterocycloalkyl groups having 3 to 39 carbon atoms, substituted or unsubstituted alkylsilyl groups having 1 to 39 carbon atoms, substituted or unsubstituted alkylboryl groups having 1 to 39 carbon atoms, substituted or unsubstituted arylboryl groups having 6 to 39 carbon atoms, substituted or unsubstituted arylphosphino groups having 6 to 39 carbon atoms, and substituted or unsubstituted arylsilyl groups having 6 to 39 carbon atoms.

[0012] In an exemplary embodiment, in the blue light-emitting layer, the N-type host material includes a compound having the following structural formula: ; wherein R1 and R2 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0013] In an exemplary embodiment, the thickness of the exciton modulation layer corresponding to the blue light-emitting layer is less than or equal to 14.5 nanometers.

[0014] In an exemplary embodiment, the thickness of the blue light-emitting layer is greater than or equal to 15 nanometers and less than or equal to 45 nanometers.

[0015] In an exemplary embodiment, the thickness of the exciton modulation layer corresponding to the green light-emitting layer is less than or equal to 30 nanometers.

[0016] In an exemplary embodiment, the thickness of the exciton modulation layer corresponding to the red light-emitting layer is less than or equal to 38 nanometers.

[0017] In one exemplary embodiment, the guest material includes a phosphorescent guest material.

[0018] In an exemplary embodiment, the guest material further includes a thermally activated delayed fluorescent guest material.

[0019] In an exemplary embodiment, in the blue light-emitting layer, the phosphorescent guest material includes a compound having the following structural formula: ; wherein R1 and R3 are the same or different and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted a substituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted R2 is independently selected from the group consisting of a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or an unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0020] In a second aspect, an embodiment of the present disclosure provides a display substrate comprising a plurality of OLED elements, wherein at least one of the OLED elements is an OLED element having the structure described above.

[0021] In a third aspect, an embodiment of the present disclosure provides a display device comprising the display substrate as described above.

[0022] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description and the drawings.

[0023] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0025] Figure 1 is a schematic structural diagram of an OLED element in an exemplary embodiment; Figure 2 is a schematic structural diagram of an OLED element in another exemplary embodiment; Figure 3 is a schematic structural diagram of an OLED element in another exemplary embodiment; Figure 4 is a schematic structural diagram of an OLED element in another exemplary embodiment; Figure 5 is a summary diagram of exciton recombination ratios of the light-emitting layer at different thicknesses of an experimental example in an exemplary embodiment; Figure 6 is a schematic structural diagram of an OLED element in another exemplary embodiment; Figure 7 is a schematic structural diagram of an OLED element in another exemplary embodiment; Figure 8 A schematic diagram of the planar structure of a display substrate; Figure 9 A schematic diagram of the cross-sectional structure of a display substrate; Figure 10 In another exemplary embodiment Figure 9 Schematic diagram of the cross-sectional structure of the light-emitting element; Figure 11 A structural diagram of a display device. DETAILED DESCRIPTION

[0026] The present disclosure describes a plurality of embodiments, but this description is exemplary rather than restrictive, and it will be apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present disclosure. Although many possible feature combinations are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0027] The present disclosure includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The disclosed embodiments, features, and elements of the present disclosure may also be combined with any conventional features or elements to form a unique inventive solution defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in this disclosure may be implemented individually or in any appropriate combination. Therefore, the embodiments are not subject to other limitations except for the limitations set forth in the appended claims and their equivalents. In addition, various modifications and changes may be made within the scope of protection of the appended claims.

[0028] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be understood by those skilled in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation on the claims. In addition, the claims to the method and / or process should not be limited to performing their steps in the order written, and those skilled in the art can readily understand that these orders can be changed and still remain within the spirit and scope of the disclosed embodiments.

[0029] In the drawings, the size of one or more components, layer thicknesses, or regions may be exaggerated for clarity. Therefore, one embodiment of the present disclosure is not necessarily limited to these dimensions, and the shapes and sizes of one or more components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate idealized examples, and one embodiment of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0030] In this specification, ordinal numbers such as "first," "second," and "third" are provided to avoid confusion among constituent elements, and are not intended to limit the number. "Multiple" in this disclosure means two or more.

[0031] In this specification, for convenience, words and phrases indicating orientation or positional relationships, such as "middle," "upper," "lower," "front," "back," "vertical," "horizontal," "top," "bottom," "inside," and "outside," are used to illustrate the positional relationships of constituent elements with reference to the accompanying drawings. This is merely for the purpose of facilitating the description of this specification and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present disclosure. The positional relationships of constituent elements may be appropriately changed depending on the orientation of the constituent elements being described. Therefore, the present disclosure is not limited to the words and phrases described in the specification and may be appropriately replaced depending on the circumstances.

[0032] In this specification, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, removable, or integral connections; mechanical or electrical connections; direct connections, indirect connections through intermediaries, or internal communication between two components. Those skilled in the art will understand the meaning of these terms in this disclosure based on the specific circumstances.

[0033] In this specification, "electrically connected" includes components connected together via an element having some electrical function. There are no particular limitations on the "element having some electrical function" as long as it enables transmission of electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components with various functions.

[0034] In this specification, "parallel" refers to a state where the angle formed by two straight lines is greater than -10° and less than 10°, and thus also includes a state where the angle is greater than -5° and less than 5°. Furthermore, "perpendicular" refers to a state where the angle formed by two straight lines is greater than 80° and less than 100°, and thus also includes a state where the angle is greater than 85° and less than 95°.

[0035] The basic "anode-light-emitting layer-cathode" structure of an OLED element resembles a "sandwich." The light-emitting material (light-emitting layer) is spin-coated, dip-coated, or vacuum-evaporated onto a conductive glass substrate. The cathode material is then applied and connected to a power source to create an organic electroluminescent element. OLED elements utilize injection-type luminescence. Driven by voltage, the anode injects holes into the light-emitting layer, while the cathode injects electrons. The holes and electrons meet and combine in the light-emitting layer to form excitons. The excitons recombine and transfer energy to the light-emitting material, which emits light through a process called radiative relaxation.

[0036] Currently, the most widely used OLED devices include fluorescent OLEDs and phosphorescent OLEDs, depending on the luminescent material. Under electrical excitation, organic materials generate 25% singlet excitons and 75% triplet excitons. For fluorescent materials, due to the principle of spin conservation, only 25% of singlet excitons can generate photons through radiative transitions. This results in a maximum internal quantum efficiency (IQE) of less than 25% for fluorescent OLEDs. Even accounting for triplet-triplet annihilation (TTA) effects, the maximum IQE still falls below 40%. Unlike fluorescent materials, triplet excitons in phosphorescent materials can emit photons through radiative transitions due to spin-orbit coupling from heavy metals. This allows phosphorescent OLEDs to theoretically achieve a maximum IQE of 100%, significantly improving device efficiency. However, blue phosphorescent materials have a short lifetime, and currently, the majority of blue-emitting devices in mass production are still blue fluorescent.

[0037] An embodiment of the present disclosure provides an OLED element, comprising: an anode, an organic light-emitting layer, and a cathode stacked in sequence, wherein the organic light-emitting layer comprises a light-emitting layer and an exciton modulation layer, the exciton modulation layer is in contact with the light-emitting layer and is located on a side of the light-emitting layer close to or away from the anode; the light-emitting layer comprises a first host material, a second host material, and a guest material; the exciton modulation layer comprises the first host material and the second host material, and the mixing ratio of the first host material and the second host material is greater than or equal to 10:1 and less than or equal to 1:1.

[0038] The OLED element provided by the embodiment of the present disclosure forms an exciton modulation layer on the side of the light-emitting layer close to or away from the anode, making the exciton recombination area wider, thereby improving the balance of carrier transmission, reducing triplet energy level accumulation, avoiding material degradation caused by exciton bombardment of the interface, and helping to extend the service life of the OLED element.

[0039] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0040] Figure 1 FIG. 1 is a schematic diagram of the structure of an OLED element in an exemplary embodiment. Figure 1As shown, the OLED element includes an anode 10, an organic light-emitting layer and a cathode 90 stacked in sequence. The organic light-emitting layer may include a light-emitting layer 50 and an exciton modulation layer 41. The light-emitting layer 50 can emit light under the voltage drive of the anode 10 and the cathode 90. The exciton modulation layer 41 can be in direct contact with the light-emitting layer 50 and can be located on the side of the light-emitting layer 50 close to the anode 10. The exciton modulation layer 41 can make the exciton recombination area wider, improve the balance of carrier transfer, reduce the accumulation of triplet energy levels, avoid material degradation caused by exciton bombardment of the interface, and help extend the service life of the OLED element. In other embodiments, the exciton modulation layer 41 can also be located on the side of the light-emitting layer 50 away from the anode 10.

[0041] In an exemplary embodiment, the light-emitting layer may be any one of a red light-emitting layer, a green light-emitting layer, a blue light-emitting layer, or a white light-emitting layer. The light-emitting layer may also be of other colors, which is not limited in the present disclosure.

[0042] Figure 2 FIG. 1 is a schematic structural diagram of an OLED element in another exemplary embodiment. Figure 2 As shown, the OLED element includes an anode 10, a cathode 90, and an organic light-emitting layer disposed between the anode 10 and the cathode 90. In an exemplary embodiment, the organic light-emitting layer may include a stacked electron blocking layer 40, an exciton modulation layer 41, a light-emitting layer 50, and a hole blocking layer 60. The electron blocking layer 40 is disposed between the anode 10 and the exciton modulation layer 41, and the hole blocking layer 60 is disposed between the light-emitting layer 50 and the cathode 90. In an exemplary embodiment, the electron blocking layer 40 is configured to form a migration barrier for electrons, preventing electrons from migrating out of the light-emitting layer 50. The light-emitting layer 50 is configured to allow electrons and holes to recombine and emit light. The hole blocking layer 60 is configured to form a migration barrier for holes, preventing holes from migrating out of the light-emitting layer 50.

[0043] Figure 3 FIG. 1 is a schematic structural diagram of an OLED element in another exemplary embodiment. Figure 3As shown, the OLED element includes an anode 10, a cathode 90, and an organic light-emitting layer disposed between the anode 10 and the cathode 90. In an exemplary embodiment, the organic light-emitting layer may include a stacked hole injection layer 20, a hole transport layer 30, an electron blocking layer 40, an exciton modulation layer 41, a light-emitting layer 50, a hole blocking layer 60, an electron transport layer 70, and an electron injection layer 80. The hole injection layer 20, the hole transport layer 30, the electron blocking layer 40, and the exciton modulation layer 41 are sequentially disposed between the anode 10 and the light-emitting layer 50, with the hole injection layer 20 connected to the anode 10 and the exciton modulation layer 41 connected to the light-emitting layer 50. The hole blocking layer 60, the electron transport layer 70, and the electron injection layer 80 are sequentially disposed between the light-emitting layer 50 and the cathode 90, with the hole blocking layer 60 connected to the light-emitting layer 50, the electron injection layer 80 connected to the cathode 90, and the electron transport layer 70 disposed between the hole blocking layer 60 and the electron injection layer 80. In an exemplary embodiment, the hole injection layer 20 is configured to lower the barrier to hole injection from the anode, so that holes can be effectively injected from the anode into the light-emitting layer 50. The hole transport layer 30 is configured to achieve a directional, orderly, and controllable migration of injected holes. The electron transport layer 70 is configured to achieve a directional, orderly, and controllable migration of injected electrons. The electron injection layer 80 is configured to lower the barrier to electron injection from the cathode, so that electrons can be effectively injected from the cathode 90 into the light-emitting layer 50. The functions of the remaining film layers can be referred to the aforementioned description. Figure 1 and Figure 2 The description is not repeated here.

[0044] In an exemplary embodiment, the light-emitting layer 50 may include a host material and a guest material doped within the host material, with the guest material having a certain doping ratio. Within this doping ratio range, the host material effectively transfers exciton energy to the guest material, thereby stimulating luminescence. Furthermore, the host material "dilutes" the guest material, effectively reducing intermolecular collisions and fluorescence quenching caused by energy collisions between guest molecules, thereby improving luminescence efficiency and device life. The host material may include a first host material and a second host material, that is, the host material may be a mixture of the first and second host materials. In an exemplary embodiment, the host material for the blue light-emitting layer may be an anthracene derivative, AND, or MAND, while the guest material for the blue light-emitting layer may be a pyrene derivative or a styrene derivative, such as DPVBi. The present disclosure does not limit the host and guest materials for the blue light-emitting layer. The host and guest materials for light-emitting layers of other colors may also be selected as needed, and the present disclosure does not limit this.

[0045] In an exemplary embodiment, the first host material, the second host material, and the guest material can be co-evaporated through a multi-source evaporation process so that the first host material, the second host material, and the guest material are uniformly dispersed in the light-emitting layer. The mixing ratio and the doping ratio can be regulated by controlling the evaporation rate of the first host material, the second host material, or the guest material during the evaporation process.

[0046] In an exemplary embodiment, anode 10 may be made of a material with a high work function. For bottom-emission devices, anode 10 may be made of a transparent oxide material, such as indium tin oxide (ITO) or indium zinc oxide (IZO). For top-emission devices, anode 10 may be made of a composite structure of a metal and a transparent oxide, such as Ag / ITO, Ag / IZO, or ITO / Ag / ITO.

[0047] In an exemplary embodiment, for a top-emission OLED, cathode 90 may be formed using a metal material through an evaporation process. The metal material may be magnesium (Mg), silver (Ag), or aluminum (Al), or an alloy material such as a Mg:Ag alloy. For a bottom-emission OLED, cathode 90 may be formed using magnesium (Mg), silver (Ag), aluminum (Al), or a Mg:Ag alloy.

[0048] In an exemplary embodiment, the hole injection layer 20 may be made of an inorganic oxide, such as molybdenum oxide, silver oxide, tungsten oxide, or manganese oxide, or may be made of a p-type dopant of a strong electron-withdrawing system and a dopant of a hole transport material, such as hexacyanohexaazatriphenylene (HATCN), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4-TCNQ), or 1,2,3-tris[(cyano) (4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane.

[0049] In an exemplary embodiment, the hole transport layer 30 and the electron blocking layer 40 may be made of aromatic amines or carbazole materials having hole transport properties, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluorene-9-yl)- )triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (4DFLDPBi), 4,4'-bis(9-carbazolyl)biphenyl (CBP), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (PCzPA) or 4,4',4''-tris(carbazol-9-yl)triphenylamine (TCTA), etc.

[0050] In an exemplary embodiment, the electron transport layer 70 and the hole blocking layer 60 may be made of aromatic heterocyclic compounds, such as imidazole derivatives such as benzimidazole derivatives, imidazopyridine derivatives, and benzimidazolephenanthridine derivatives; oxazine derivatives such as pyrimidine derivatives and triazine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives, and other compounds containing a nitrogen-containing six-membered ring structure (including compounds having a phosphine oxide-based substituent on the heterocyclic ring), etc. For example, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole (TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole (p-EtTAZ), bathocuproine (BCP) or 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi).

[0051] In an exemplary embodiment, the electron injection layer 80 may be made of an alkali metal or metal, such as lithium fluoride (LiF), ytterbium (Yb), magnesium (Mg), or calcium (Ca), or a compound of these alkali metals or metals.

[0052] Figure 4 FIG. 1 is a schematic structural diagram of an OLED element in another exemplary embodiment. Figure 4 As shown, the OLED element includes an anode 10 , a cathode 90 , and an organic light emitting layer disposed between the anode 10 and the cathode 90 . Figure 4 and Figure 3 The difference is that the organic light emitting layer further includes a capping layer (CPL) 91 and a protective layer 92 sequentially arranged on the side of the cathode 90 away from the anode 10. The rest of the structure can refer to the above description. Figure 3 The description is not repeated here.

[0053] like Figure 4 As shown, the cover layer 91 not only protects the cathode 90 but also helps to enhance the light extraction efficiency of the OLED element.

[0054] In an exemplary embodiment, protective layer 92 may be made of lithium fluoride (LiF). LiF has a high refractive index, which not only helps improve light extraction efficiency but also provides some UV protection, preventing subsequent UV processes from adversely affecting other film layers. In other embodiments, protective layer 92 may also be made of other materials with similar functions.

[0055] In an exemplary embodiment, the light-emitting layer 50 may be a blue light-emitting layer. The material of the blue light-emitting layer may include a combination of quaternary materials, wherein the quaternary material may include two host materials and two guest materials. The first host material may be a P-type blue host (PBH) material, the second host material may be an N-type blue host (NBH) material, the first guest material may be a blue phosphorescent guest (BPD) material, and the second guest material may be a thermally activated delayed fluorescence blue dopant (TADF BD) material. The mixing ratio between the P-type blue host material and the N-type blue host material may be greater than or equal to 10:1 and less than or equal to 1:1, the doping ratio of the blue phosphorescent guest material may be greater than or equal to 5% and less than or equal to 15%, and the doping ratio of the thermally activated delayed fluorescence blue guest material may be greater than or equal to 0.5% and less than or equal to 2.5%. In the embodiments of the present disclosure, the mixing ratio and the doping ratio can be understood as an equivalent thickness ratio. When the thickness of the light-emitting layer 50 and the area occupied by the light-emitting layer 50 are pre-set, the equivalent thickness occupied by each material in the light-emitting layer 50 can be calculated based on the mixing ratio and the doping ratio, and the amount of each material used can be further obtained. Since multiple materials are co-evaporated during the preparation process, the light-emitting layer 50 formed includes a mixture of multiple materials. Therefore, the thickness ratio here is an equivalent concept, not the thickness of the material in the actual product. "Thickness" can refer to the dimension in the direction perpendicular to the film layer, Figure 4 The thickness of the anode 10 is indicated as Dy, and the thicknesses of other film layers are omitted.

[0056] The P-type blue host material can be a compound having the structural formula shown in Formula 1: Formula 1 In Formula 1, the molecular mass of R1 is between 70 and 260; R1 is independently selected from a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamine group having 6 to 39 carbon atoms, a substituted or an unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0057] The N-type blue host material may be a compound having the structural formula shown in Formula 2: Formula 2 In Formula 2, R1 and R2 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 The present invention further comprises a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphine group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0058] The blue phosphorescent guest material may be a compound having the structural formula shown in Formula 3: Formula 3 wherein R1 and R3 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms. R2 is independently selected from a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0059] In example embodiments, the thickness of the blue light emitting layer may be greater than or equal to 15 nanometers and less than or equal to 45 nanometers.

[0060] In other embodiments, the material of the blue light-emitting layer may include a combination of ternary materials, which may include two host materials and one guest material. The first host material may be a P-type blue host material, the second host material may be an N-type blue host material, and the guest material may be a blue phosphorescent guest material. The mixing ratio between the P-type blue host material and the N-type blue host material may be greater than or equal to 10:1 and less than or equal to 1:1, and the doping ratio of the blue phosphorescent guest material may be greater than or equal to 5% and less than or equal to 15%. The material composition of the blue light-emitting layer and the ratios between the components can be adjusted as needed.

[0061] In an exemplary embodiment, the material of the exciton modulation layer 41 arranged corresponding to the blue light-emitting layer may include a P-type blue host material and an N-type blue host material, and the mixing ratio between the P-type blue host material and the N-type blue host material may be greater than or equal to 10:1 and less than or equal to 1:1.

[0062] In an exemplary embodiment, the thickness of the exciton modulation layer 41 may be greater than 0 and less than or equal to 14.5 nanometers. By setting the thickness of the exciton modulation layer 41 to be less than or equal to 14.5 nanometers, it is possible to avoid an excessively long transmission path caused by an excessively thick exciton modulation layer 41, which indirectly reduces the exciton transmission rate.

[0063] In an exemplary embodiment, the material of the hole transport layer 30 may be a compound having the structural formula shown in Formula 4: Formula 4 In Formula 4, R1 to R5 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 The present invention further comprises a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphine group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0064] In exemplary embodiments, the hole transport layer 30 may have a thickness of about 100 nanometers.

[0065] In an exemplary embodiment, the hole injection layer 20 may use a p-type dopant and a dopant of a hole transport material, and the doping ratio of the p-type dopant may be about 5%.

[0066] In an exemplary embodiment, the hole injection layer 20 may have a thickness of about 10 nanometers.

[0067] In an exemplary embodiment, the thickness of the electron blocking layer 40 may be about 5 nanometers.

[0068] In an exemplary embodiment, the hole blocking layer 60 disposed corresponding to the blue light emitting layer may be made of an N-type blue host material and may have a thickness of about 5 nanometers.

[0069] In an exemplary embodiment, the material of the electron transport layer 70 may be a compound having the structural formula shown in Formula 5: Formula 5 In Formula 5, R1 to R3 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 The present invention further comprises a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphine group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

[0070] In an exemplary embodiment, the thickness of the electron transport layer 70 may be about 30 nanometers.

[0071] In an exemplary embodiment, the material of the electron injection layer 80 may be metal ytterbium. The thickness of the electron injection layer 80 may be about 1 nanometer.

[0072] In an exemplary embodiment, the cathode 90 may include an alloy of Mg:Ag, and the mass fraction ratio of Mg:Ag may be approximately 9: 1. The thickness of the cathode 90 may be approximately 14 nanometers.

[0073] In an exemplary embodiment, the material of the cover layer 91 may be a compound having the structural formula shown in Formula 6: Formula 6 In Formula 6, Y1 is selected from C 6-40 Aryl, C 2-60 Heteroaryl, C 6-60 Aryloxy, C 1-39 Alkoxy, C 6-39 Arylamine, C 3-39 Cycloalkyl, C 3-39 Heterocycloalkyl, C 1-39 Alkylsilyl, C 1-39 Alkylboryl, C 6-39 Arylboryl, C 6-39 Arylphosphino or C 6-39 Arylsilyl; wherein C 2-60Heteroaryl and C 3-39 The heteroatoms in the heterocycloalkyl group are each independently selected from N, O or S.

[0074] In an exemplary embodiment, the capping layer 91 may have a thickness of approximately 75 nanometers.

[0075] In an exemplary embodiment, the material of the protective layer 92 may be lithium fluoride. The thickness of the protective layer 92 may be approximately 55 nanometers.

[0076] The scheme in the embodiment of the present disclosure is described below by comparing the effects of an experimental example and five comparative examples.

[0077] Experimental example: Figure 4 The structure shown is the same, and the light-emitting layer is a blue light-emitting layer, meaning the OLED element in the experimental example is a blue phosphorescent OLED element. The hole injection layer 20 is doped with a p-type dopant and a hole transport material, with the p-type dopant doping ratio being approximately 5%. The hole injection layer 20 has a thickness of approximately 10 nanometers. The electron blocking layer 40 has a thickness of approximately 5 nanometers. The exciton modulation layer 41 comprises a P-type blue host material and an N-type blue host material, with the mixing ratio of the P-type blue host material and the N-type blue host material being 3:2. The thickness of the exciton modulation layer 41 is approximately 10 nanometers. The light-emitting layer 50 is a blue light-emitting layer, with the mixing ratio of the P-type blue host material and the N-type blue host material being approximately 3:2. The doping ratio of the blue phosphorescent guest material is greater than or equal to 5% and less than or equal to 15%, and the doping ratio of the thermally activated delayed fluorescent blue guest material is greater than or equal to 0.5% and less than or equal to 2.5%. The light-emitting layer 50 has a thickness of approximately 30 nanometers. The hole blocking layer 60 can be approximately 5 nanometers thick. The thickness of electron transport layer 70 is approximately 30 nanometers. Electron injection layer 80 is made of ytterbium metal and has a thickness of approximately 1 nanometer. Cathode 90 is made of a Mg:Ag alloy, with a mass ratio of Mg:Ag of approximately 9:1. Cathode 90 is approximately 14 nanometers thick. Capping layer 91 is approximately 75 nanometers thick. Protective layer 92 is approximately 55 nanometers thick.

[0078] Comparative Example 1: The only difference from the experimental example is the thickness of the exciton modulation layer 41 and the light-emitting layer 50. In Comparative Example 1, the thickness of the exciton modulation layer 41 is about 15 nanometers, and the thickness of the light-emitting layer 50 is about 25 nanometers.

[0079] Comparative Example 2: The only difference from the experimental example is that the positions of the exciton modulation layer 41 and the light-emitting layer 50 are swapped. In Comparative Example 2, the exciton modulation layer 41 is located between the light-emitting layer 50 and the hole blocking layer 60 .

[0080] Comparative Example 3: The only difference from Comparative Example 2 is the thickness of the exciton modulation layer 41 and the light-emitting layer 50. In Comparative Example 3, the thickness of the exciton modulation layer 41 is about 15 nanometers, and the thickness of the light-emitting layer 50 is about 25 nanometers.

[0081] Comparative Example 4: The only difference from the experimental example is that the light-emitting layer 50 is eliminated, and the thickness of the exciton modulation layer 41 is about 40 nanometers.

[0082] Comparative Example 5: The only difference from the experimental example is that the exciton modulation layer 41 is eliminated, and the thickness of the light-emitting layer 50 is about 40 nanometers.

[0083] Blue phosphorescent OLED elements from experimental examples and several examples were tested. The test details included the voltage and luminous efficiency of the different blue phosphorescent OLED elements at a brightness of 1000 nits (nits), as well as the time it takes for the initial brightness to decrease to 95% (LT95(h)@1000nit). The voltage is measured in volts (V), the luminous efficiency is measured in candela per ampere (cd / A), and the time it takes for the initial brightness to decrease to 95% is measured in hours (h). Table 1 compares the results of the experimental examples with those of several comparative examples. Table 1 shows the results after converting the raw data, using the data from comparative example 1 as a baseline. The data from the remaining examples are converted to percentages of the baseline for a more intuitive comparison.

[0084] Table 1

[0085] As shown in Table 1, the voltage, luminous efficiency, and the time for the brightness to decrease to 95% of the initial brightness of the experimental example and comparative examples 1 to 3 are all greater than those of comparative example 5. It can be seen that the provision of the exciton modulation layer 41 in the OLED element has a positive effect on reducing the driving voltage, improving the luminous efficiency, and improving the brightness retention time. In combination with comparative example 4, it can be seen that the exciton modulation layer 41 needs to be combined with the light-emitting layer 50 to achieve a better effect. Regarding the positional relationship between the exciton modulation layer 41 and the light-emitting layer 50, the experimental example and comparative example 1 are to set the exciton modulation layer 41 on the side of the light-emitting layer 50 close to the anode 10, and comparative examples 2 and 3 are to set the exciton modulation layer 41 on the side of the light-emitting layer 50 away from the anode 10. From the data, it can be seen that the exciton modulation layer 41 is set on the side of the light-emitting layer 50 close to the anode 10. The effect is better. It can be considered that the exciton modulation layer 41 is better when it is set on the side of the light-emitting layer 50 close to the anode 10. Comparing the experimental example with comparative example 1, we can see that while the luminous efficiency of the two is similar, the experimental example has a lower voltage and a longer brightness retention time, resulting in a superior effect. This shows that a thinner exciton modulation layer 41 is more conducive to improving the luminous effect of the OLED element, a conclusion that can also be verified by comparing comparative examples 2 and 3.

[0086] Figure 5 This is a summary diagram of the exciton recombination ratios at different thicknesses of the light-emitting layer of an experimental example in an exemplary embodiment. By taking a cross section parallel to the light-emitting layer 50 at different height positions of the light-emitting layer 50 and measuring the exciton recombination ratios of the light-emitting layer 50 at the cross section, the distribution of the exciton recombination ratios at different height positions of the light-emitting layer 50 can be obtained. Figure 5 As shown, the abscissa represents the height ratio of the light-emitting layer, and the ordinate represents the exciton recombination ratio. Figure 5 In the middle, cross sections are uniformly taken on the light emitting layer 50 in the direction away from the anode 10 for detection, and a cross section is selected at every interval of about 10% of the height ratio. Figure 5 The eight cross sections are located in the height ranges of the light emitting layer 50 with a height ratio of 0 to 0.1, 0.1 to 0.2, 0.2 to 0.3, 0.3 to 0.4, 0.4 to 0.5, 0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8 and 0.8 to 0.9. Figure 5It can be seen that at each detection cross section before the height ratio reaches 0.8, the exciton recombination ratio is evenly distributed and is distributed between 10% and 15%. This shows that the exciton modulation layer 41 improves the exciton transmission conditions at different height positions of the light-emitting layer 50 in a relatively balanced manner. In the height range of 0.8 to 0.9, the exciton recombination ratio decreases. This is because this position is far away from the exciton modulation layer 41, and the exciton modulation layer 41 has a relatively small improvement on the exciton transmission conditions at this position. Figure 5 It can be seen from the figure that, by providing the exciton modulation layer 41 , the exciton transmission of the entire light-emitting layer 50 can be improved in a balanced manner, and the improvement effect is considerable.

[0087] The fundamental reason for the short lifespan of blue phosphorescent OLED devices is the high T1 energy level of the blue phosphorescent material, which leads to an unstable material structure. When the device is illuminated for a long time, excitons continuously bombard the interface, easily causing material degradation and thus shortening the device lifespan. In this embodiment, the provision of the exciton modulation layer 41 widens the carrier recombination area and reduces triplet energy level accumulation, which not only helps improve luminous efficiency but also helps extend the lifespan of the blue phosphorescent OLED device.

[0088] In an exemplary embodiment, Figure 4 The light-emitting layer 50 shown in the figure can be a green light-emitting layer. The material of the green light-emitting layer can include a combination of quaternary materials, which can include two host materials and two guest materials. The first host material can be a P-type green host (PGH) material, the second host material can be an N-type green host (NGH) material, the first guest material can be a green phosphorescent guest (GPD) material, and the second guest material can be a thermally activated delayed fluorescence green guest (TADF GD) material. The mixing ratio of the P-type green host material to the N-type green host material can be greater than or equal to 10:1 and less than or equal to 1:1. The doping ratio of the green phosphorescent guest material can be greater than or equal to 5% and less than or equal to 15%, and the doping ratio of the thermally activated delayed fluorescence green guest material can be greater than 0 and less than or equal to 8%. The quaternary materials of the green light-emitting layer can be selected as needed and are not further described here.

[0089] In an exemplary embodiment, the material of the green light-emitting layer may include a ternary material combination, which may include two host materials and one guest material. The first host material may be a P-type green host material, the second host material may be an N-type green host material, and the guest material may be a green phosphorescent guest material. The mixing ratio of the P-type green host material to the N-type green host material may be greater than or equal to 10:1 and less than or equal to 1:1, and the doping ratio of the green phosphorescent guest material may be greater than or equal to 5% and less than or equal to 15%. The material composition of the green light-emitting layer and the ratios between the components can be adjusted as needed.

[0090] In example embodiments, the thickness of the green light emitting layer may be greater than or equal to 20 nanometers and less than or equal to 60 nanometers.

[0091] In an exemplary embodiment, the material of the exciton modulation layer 41 arranged corresponding to the green light-emitting layer may include a P-type green main material and an N-type green main material, and the mixing ratio of the P-type green main material and the N-type green main material may be greater than or equal to 10:1 and less than or equal to 1:1.

[0092] In an exemplary embodiment, the thickness of the exciton modulation layer 41 disposed corresponding to the green light emitting layer may be greater than 0 and less than or equal to 30 nanometers. In other embodiments, the exciton modulation layer 41 may also be disposed on a side of the light emitting layer 50 away from the anode 10 .

[0093] In an exemplary embodiment, Figure 4 The light-emitting layer 50 shown in the figure can be a red light-emitting layer. The material of the red light-emitting layer can include a combination of quaternary materials, which can include two host materials and two guest materials. The first host material can be a P-type red host (PRH) material, the second host material can be an N-type red host (NRH) material, the first guest material can be a red phosphorescent guest (RPD) material, and the second guest material can be a thermally activated delayed fluorescence red guest (TADF RD) material. The mixing ratio of the P-type red host material to the N-type red host material can be greater than or equal to 10:1 and less than or equal to 1:1. The doping ratio of the red phosphorescent guest material can be greater than 0 and less than or equal to 7%, and the doping ratio of the thermally activated delayed fluorescence red guest material can be greater than 0 and less than or equal to 10%. The quaternary materials of the red light-emitting layer can be selected as needed and are not further described here.

[0094] In exemplary embodiments, the light-emitting layer can be prepared using a co-host or pre-mixing method. Co-hosting involves simultaneously evaporating a P-type host material and an N-type host material. Pre-mixing involves first mixing the P-type host material and the N-type host material into a single material before evaporating.

[0095] In an exemplary embodiment, the material of the red light-emitting layer may include a ternary material combination, which may include two host materials and one guest material. The first host material may be a P-type red host material, the second host material may be an N-type red host material, and the guest material may be a red phosphorescent guest material. The mixing ratio of the P-type red host material to the N-type red host material may be greater than or equal to 10:1 and less than or equal to 1:1, and the doping ratio of the red phosphorescent guest material may be greater than 0 and less than or equal to 7%. The material composition of the red light-emitting layer and the ratios of the components may be adjusted as needed.

[0096] In example embodiments, the thickness of the red light emitting layer may be greater than or equal to 26 nanometers and less than or equal to 62 nanometers.

[0097] In an exemplary embodiment, the material of the exciton modulation layer 41 arranged corresponding to the red light-emitting layer may include a P-type red main material and an N-type red main material, and the mixing ratio of the P-type red main material and the N-type red main material may be greater than or equal to 10:1 and less than or equal to 1:1.

[0098] In an exemplary embodiment, the thickness of the exciton modulation layer 41 corresponding to the red light emitting layer may be greater than 0 and less than or equal to 38 nanometers. In other embodiments, the exciton modulation layer 41 may also be disposed on a side of the light emitting layer 50 away from the anode 10 .

[0099] Figure 6 FIG. 1 is a schematic structural diagram of an OLED element in another exemplary embodiment. Figure 6 As shown, the OLED element may include a first hole injection layer 20-1, a first hole transport layer 30-1, a first electron blocking layer 40-1, a first exciton modulation layer 41-1, a first light-emitting layer 50-1, a first hole blocking layer 60-1, a first electron transport layer 70-1, a charge generation layer (CGL) CGL, a second hole injection layer 20-2, a second hole transport layer 30-2, a second electron blocking layer 40-2, a second exciton modulation layer 41-2, a second light-emitting layer 50-2, a second hole blocking layer 60-2, a second electron transport layer 70-2, an electron injection layer 80, a cathode 90 and a capping layer 91, which are sequentially arranged above the anode 10. Figure 6In the OLED element shown, two light-emitting layers of the same color are stacked between an anode 10 and a cathode 90. The use of an anode 10 and a cathode 90 can control the first light-emitting layer 50-1 and the second light-emitting layer 50-2 to emit light synchronously. When the light from the two light-emitting layers is superimposed, it not only helps to improve the light efficiency of the element, but also helps to reduce the intensity of the driving signal and increase the life of the element. In addition, in the process of using OLEDs of different colors to display images, Figure 6 The color gamut performance of the OLED with the shown structure is also better.

[0100] Figure 6 In the embodiment, a single OLED element including two stacked light-emitting layers of the same color is used as an example for illustration. In other embodiments, a larger number of light-emitting layers can be stacked in a single OLED element as needed.

[0101] Figure 7 FIG. 4 is a schematic structural diagram of an OLED element in another exemplary embodiment. Figure 7 The OLED element shown includes a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer stacked between an anode 10 and a cathode 90 to form a tandem OLED (TandemOLED) structure. The OLED element can emit white light. Figure 7 In the figure, a red light-emitting layer, a green light-emitting layer and a blue light-emitting layer are stacked in sequence on the anode 10 for illustration. The present disclosure does not limit the stacking order of the three light-emitting layers.

[0102] like Figure 7 As shown, the RO membrane layer includes Figure 4 There are eight film layers from the hole injection layer 20 to the electron injection layer 80, and the light-emitting layer 50 is a red light-emitting layer. Figure 4 The BO layer includes eight layers from the hole injection layer 20 to the electron injection layer 80, and the light-emitting layer 50 is a green light-emitting layer. Figure 4 There are eight film layers from the hole injection layer 20 to the electron injection layer 80, and the light-emitting layer 50 is a blue light-emitting layer. The parameters such as the material and thickness of each film layer can refer to the above Figure 4 The description is not repeated here.

[0103] In an exemplary embodiment, a first charge generation layer CGL1 may be disposed between the RO membrane layer and the GO membrane layer, and a second charge generation layer CGL2 may be disposed between the GO membrane layer and the BO membrane layer.

[0104] In other embodiments, Figure 7 The electron injection layer can be omitted in the RO membrane layer and the GO membrane layer, and the electron injection layer can be provided in the BO membrane layer. Figure 7The OLED element shown may be provided with an electron injection layer only on the side close to the cathode 90 .

[0105] Figure 7 In the example, an exciton modulation layer is provided corresponding to each color of the light-emitting layer. In other embodiments, an exciton modulation layer may be provided only in the blue light-emitting layer, and no exciton modulation layer may be provided in the red and green light-emitting layers. Whether to provide corresponding exciton modulation layers in the red and green light-emitting layers can be determined as needed. The embodiments of the present disclosure also provide a display substrate comprising a plurality of OLED elements, wherein at least one OLED element employs an OLED element having the structure described in the above embodiments.

[0106] In an exemplary embodiment, the OLED elements of the display substrate may include a red OLED element, a green OLED element, and a blue OLED element. Alternatively, the OLED elements of the display substrate may include a red OLED element, a green OLED element, a blue OLED element, and a white OLED element. Alternatively, the OLED elements of the display substrate may include a white OLED element.

[0107] Figure 8 FIG. 1 is a schematic diagram of a planar structure of a display substrate. Figure 8 As shown, the display substrate may include a plurality of pixel units P arranged in a matrix. At least one pixel unit P may include a first sub-pixel P1 emitting a first color light, a second sub-pixel P2 emitting a second color light, and a third sub-pixel P3 emitting a third color light. Each sub-pixel may include a circuit unit and a light-emitting element. The circuit unit may include at least a pixel driving circuit. The pixel driving circuit is respectively connected to a scan signal line, a data signal line, and a light-emitting signal line. The pixel driving circuit is configured to receive a data voltage transmitted by the data signal line under the control of the scan signal line and the light-emitting signal line, and output a corresponding current to the light-emitting element. The light-emitting element in each sub-pixel is respectively connected to the pixel driving circuit of the sub-pixel. The light-emitting element is configured to emit light of corresponding brightness in response to the current output by the connected pixel driving circuit.

[0108] In an exemplary embodiment, the first subpixel P1 may be a red subpixel (R) that emits red light, the second subpixel P2 may be a blue subpixel (B) that emits blue light, and the third subpixel P3 may be a green subpixel (G) that emits green light. In an exemplary embodiment, the subpixels may be rectangular, diamond-shaped, pentagonal, or hexagonal, and the three subpixels may be arranged horizontally, vertically, or in a triangular pattern, although this disclosure is not limited thereto.

[0109] In an exemplary embodiment, a pixel unit may include four sub-pixels. For example, the four sub-pixels may include a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel that emits white (W) light. In another example, the four sub-pixels may include a red sub-pixel, a blue sub-pixel, and two green sub-pixels. In an exemplary embodiment, the four sub-pixels may be arranged horizontally, vertically, in a square, or in a diamond shape, etc., which is not limited in this disclosure.

[0110] Figure 9 FIG. 1 is a schematic diagram of a cross-sectional structure of a display substrate, illustrating a structure in which an OLED display substrate includes three sub-pixels, each of which may include an OLED element. Figure 9 As shown, on a plane perpendicular to the display substrate, the display substrate may include a driving circuit layer 102 disposed on a substrate 101, a light-emitting element 103 disposed on a side of the driving circuit layer 102 away from the substrate 101, and an encapsulation layer 104 disposed on a side of the light-emitting element 103 away from the substrate 101. In some possible implementations, the display substrate may include other film layers, such as spacers, etc., which are not limited in this disclosure.

[0111] In an exemplary embodiment, the substrate may be a flexible substrate or a rigid substrate. The flexible substrate may include a first flexible material layer, a first inorganic material layer, a semiconductor layer, a second flexible material layer, and a second inorganic material layer stacked together. The first and second flexible material layers may be made of materials such as polyimide (PI), polyethylene terephthalate (PET), or a surface-treated polymer soft film. The first and second inorganic material layers may be made of silicon nitride (SiNx) or silicon oxide (SiOx) to improve the substrate's resistance to water and oxygen. The semiconductor layer may be made of amorphous silicon (a-Si).

[0112] In an exemplary embodiment, the driving circuit layer 102 of each sub-pixel may include a plurality of transistors and storage capacitors constituting a pixel driving circuit. Figure 9In the example, each sub-pixel includes a driving transistor and a storage capacitor. In some possible implementations, the driving circuit layer 102 of each sub-pixel may include: a first insulating layer 201 disposed on a substrate; an active layer disposed on the first insulating layer; a second insulating layer 202 covering the active layer; a gate electrode and a first capacitor electrode disposed on the second insulating layer 202; a third insulating layer 203 covering the gate electrode and the first capacitor electrode; a second capacitor electrode disposed on the third insulating layer 203; a fourth insulating layer 204 covering the second capacitor electrode, with vias provided in the second insulating layer 202, the third insulating layer 203, and the fourth insulating layer 204 exposing the active layer; a source electrode and a drain electrode disposed on the fourth insulating layer 204, with the source electrode and the drain electrode respectively connected to the active layer through the vias; and a planar layer 205 covering the aforementioned structure, with a via provided in the planar layer 205 exposing the drain electrode. The active layer, gate electrode, source electrode, and drain electrode constitute the driving transistor 210, and the first capacitor electrode and the second capacitor electrode constitute the storage capacitor 211.

[0113] In an exemplary embodiment, the light-emitting element 103 may include an anode 301, a pixel definition layer 302, an organic light-emitting layer 303, and a cathode 304. The anode 301 is disposed on the planar layer 205 and connected to the drain electrode of the driving transistor 210 through a via hole provided in the planar layer 205. The pixel definition layer 302 is disposed on the anode 301 and the planar layer 205, and a pixel opening is provided in the pixel definition layer 302, exposing the anode 301. The organic light-emitting layer 303 is at least partially disposed within the pixel opening and connected to the anode 301. The cathode 304 is disposed on the organic light-emitting layer 303 and connected to the organic light-emitting layer 303. Driven by the anode 301 and cathode 304, the organic light-emitting layer 303 emits light of a corresponding color. The organic light-emitting layer 303 of each color can adopt any of the structures described in the aforementioned OLED elements.

[0114] In an exemplary embodiment, the encapsulation layer 104 may include a stacked first encapsulation layer 401, a second encapsulation layer 402 and a third encapsulation layer 403. The first encapsulation layer 401 and the third encapsulation layer 403 may be made of inorganic materials, and the second encapsulation layer 402 may be made of organic materials. The second encapsulation layer 402 is arranged between the first encapsulation layer 401 and the third encapsulation layer 403 to ensure that external water vapor cannot enter the light-emitting element 103.

[0115] Figure 10 In another exemplary embodiment Figure 9 The cross-sectional structure diagram of the light-emitting element in FIG. 1 shows the structure of the light-emitting element corresponding to the three sub-pixels. Figure 10 In the embodiment, each OLED element includes two stacked light-emitting layers of the same color on a plane perpendicular to the display substrate.

[0116] like Figure 10 As shown, each blue sub-pixel may include a first blue light-emitting layer 50B-1 and a second blue light-emitting layer 50B-2 stacked in sequence, a first blue electron blocking layer 40B-1 being provided on a side of the first blue light-emitting layer 50B-1 close to the anode 10, and a second blue electron blocking layer 40B-2 being provided on a side of the second blue light-emitting layer 50B-2 close to the anode 10. Each green sub-pixel may include a first green light-emitting layer 50G-1 and a second green light-emitting layer 50G-2 stacked in sequence, a first green electron blocking layer 40G-1 being provided on a side of the first green light-emitting layer 50G-1 close to the anode 10, and a second green electron blocking layer 40G-2 being provided on a side of the second green light-emitting layer 50G-2 close to the anode 10. Each red sub-pixel may include a first red light-emitting layer 50R-1 and a second red light-emitting layer 50R-2 stacked in sequence, a first red electron blocking layer 40R-1 is provided on the side of the first red light-emitting layer 50R-1 close to the anode 10, and a second red electron blocking layer 40R-2 is provided on the side of the second red light-emitting layer 50R-2 close to the anode 10. Figure 10 In the embodiment, only an exciton modulation layer is provided corresponding to each blue light emitting layer, and an exciton modulation layer may not be provided for the red light emitting layer and the green light emitting layer. The remaining film layers of different light emitting elements may adopt a common layer. Figure 10 In this structure, each sub-pixel can drive two light-emitting layers of the same color to emit light synchronously through a pixel driving circuit, which helps to improve the light efficiency of the display substrate, extend its service life, and improve the color gamut performance of the display substrate.

[0117] In exemplary embodiments, the thickness of the single red light emitting layer and the thickness of the single green light emitting layer may both be greater than the thickness of the single blue light emitting layer, and the thickness of the single red light emitting layer may be greater than the thickness of the single green light emitting layer.

[0118] In other embodiments, the multiple light emitting elements of the display substrate can all emit white light, and the white light forms light of different colors after passing through filter films of different colors, thereby forming a picture display. Figure 7 The OLED element of the structure shown is not described in detail here.

[0119] The present disclosure also provides a display device comprising the display substrate described above. The display device may be any product or component with a display function, such as an OLED display, a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, or a navigation system, but the present disclosure is not limited thereto.

[0120] Figure 11 FIG. 1 is a schematic diagram of the structure of a display device. Figure 11As shown, a display device may include a timing controller, a data driver, a scan driver, a light-emitting driver, and a pixel array. The timing controller is connected to the data driver, scan driver, and light-emitting driver, respectively. The data driver is connected to a plurality of data signal lines (D1 to Dn), the scan driver is connected to a plurality of scan signal lines (S1 to Sm), and the light-emitting driver is connected to a plurality of light-emitting signal lines (E1 to Eo). The pixel array may include a plurality of sub-pixels Pxij, where i and j may be natural numbers. At least one sub-pixel Pxij may include a circuit unit and a light-emitting element connected to the circuit unit. The circuit unit may include at least a pixel driving circuit, which is connected to the scan signal lines, the data signal lines, and the light-emitting signal lines, respectively. In an exemplary embodiment, the timing controller may provide grayscale values ​​and control signals suitable for the specifications of the data driver to the data driver, a clock signal and a scan start signal suitable for the specifications of the scan driver to the scan driver, and a clock signal and an emission stop signal suitable for the specifications of the light-emitting driver to the light-emitting driver. The data driver can generate data voltages to be supplied to data signal lines D1, D2, D3, ..., and Dn using grayscale values ​​and control signals received from a timing controller. For example, the data driver can sample grayscale values ​​using a clock signal and apply data voltages corresponding to the grayscale values ​​to data signal lines D1 to Dn on a per-pixel basis, where n can be a natural number. The scan driver can generate scan signals to be supplied to scan signal lines S1, S2, S3, ..., and Sm by receiving clock signals, scan start signals, and the like from the timing controller. For example, the scan driver can sequentially supply scan signals having on-level pulses to scan signal lines S1 to Sm. For example, the scan driver can be configured as a shift register and can sequentially transmit scan start signals provided in the form of on-level pulses to the next-stage circuit under the control of a clock signal, where m can be a natural number. The light driver can generate emission signals to be supplied to light signal lines E1, E2, E3, ..., and Eo by receiving clock signals, emission stop signals, and the like from the timing controller. For example, the light emitting driver may sequentially provide an emission signal having an off-level pulse to the light emitting signal lines E1 to Eo. For example, the light emitting driver may be configured in the form of a shift register and may generate an emission signal in a manner such that an emission stop signal provided in the form of an off-level pulse is sequentially transmitted to a next-stage circuit under the control of a clock signal. o may be a natural number.

[0121] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. An OLED element, comprising: An anode, an organic light-emitting layer, and a cathode stacked in sequence, wherein the organic light-emitting layer includes a light-emitting layer and an exciton modulation layer, wherein the exciton modulation layer is in contact with the light-emitting layer and is located on a side of the light-emitting layer close to or away from the anode; The light-emitting layer includes a first host material, a second host material and a guest material; The exciton modulation layer includes the first host material and the second host material, and a mixing ratio of the first host material to the second host material is greater than or equal to 10:1 and less than or equal to 1:

1.

2. The OLED element according to claim 1, wherein The light-emitting layer includes any one of a blue light-emitting layer, a red light-emitting layer and a green light-emitting layer.

3. The OLED element according to claim 2, wherein In a direction away from the anode, the OLED element includes at least two stacked light-emitting layers of the same color.

4. The OLED element according to claim 1, wherein The light-emitting layer includes three colors of light-emitting layers arranged in sequence away from the anode; the three colors of light-emitting layers include a blue light-emitting layer, a red light-emitting layer and a green light-emitting layer; the exciton modulation layer is arranged at least corresponding to the blue light-emitting layer.

5. The OLED element according to any one of claims 2 to 4, characterized in that The first body material includes a P-type body material, and the second body material includes an N-type body material.

6. The OLED element according to claim 5, characterized in that In the blue light-emitting layer, the P-type host material includes a compound having the following structural formula: ； wherein the molecular mass of R1 is between 70 and 260; R1 is independently selected from a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamine group having 6 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 1 ...oxy group having 1 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl groups having 3 to 39 carbon atoms, substituted or unsubstituted heterocycloalkyl groups having 3 to 39 carbon atoms, substituted or unsubstituted alkylsilyl groups having 1 to 39 carbon atoms, substituted or unsubstituted alkylboryl groups having 1 to 39 carbon atoms, substituted or unsubstituted arylboryl groups having 6 to 39 carbon atoms, substituted or unsubstituted arylphosphino groups having 6 to 39 carbon atoms, and substituted or unsubstituted arylsilyl groups having 6 to 39 carbon atoms.

7. The OLED element according to claim 5, characterized in that In the blue light-emitting layer, the N-type host material includes a compound having the following structural formula: ； wherein R1 and R2 are the same as or different from each other and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

8. The OLED element according to claim 5, characterized in that The thickness of the exciton modulation layer corresponding to the blue light-emitting layer is less than or equal to 14.5 nanometers.

9. The OLED element according to claim 8, characterized in that The thickness of the blue light-emitting layer is greater than or equal to 15 nanometers and less than or equal to 45 nanometers.

10. The OLED element according to claim 5, characterized in that The thickness of the exciton modulation layer corresponding to the green light-emitting layer is less than or equal to 30 nanometers.

11. The OLED element according to claim 5, characterized in that The thickness of the exciton modulation layer corresponding to the red light-emitting layer is less than or equal to 38 nanometers.

12. The OLED element according to claim 5, characterized in that The guest material includes a phosphorescent guest material.

13. The OLED element according to claim 12, wherein: The guest material also includes a thermally activated delayed fluorescent guest material.

14. The OLED element according to claim 12, wherein In the blue light-emitting layer, the phosphorescent guest material includes a compound having the following structural formula: ； wherein R1 and R3 are the same or different and are each independently selected from hydrogen, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted a substituted arylamino group having 6 to 39 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted R2 is independently selected from the group consisting of a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 60 carbon atoms, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted heterofluorenyl group, a substituted or unsubstituted aryloxy group having 6 to 60 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 39 carbon atoms, a substituted or unsubstituted arylamino group having 6 to 39 carbon atoms, a substituted or an unsubstituted cycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 3 to 39 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 39 carbon atoms, a substituted or unsubstituted alkylboryl group having 1 to 39 carbon atoms, a substituted or unsubstituted arylboryl group having 6 to 39 carbon atoms, a substituted or unsubstituted arylphosphino group having 6 to 39 carbon atoms, and a substituted or unsubstituted arylsilyl group having 6 to 39 carbon atoms.

15. A display substrate, characterized in that: The method comprises a plurality of OLED elements, wherein at least one of the OLED elements is the OLED element according to any one of claims 1 to 14. 16 . A display device comprising the display substrate according to claim 15 .

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