Organic electroluminescent devices, display substrates and display devices

Abstract

This disclosure provides an organic electroluminescent device, a display substrate, and a display apparatus. The organic electroluminescent device includes an anode, a cathode, and a light-emitting layer disposed between the anode and the cathode. The light-emitting layer is made of a host material and a guest material. The host material includes either a first host material or a second host material. The first host material includes a first P-type material, a first N-type material, a second P-type material, and a second N-type material satisfying a preset energy level range. The second host material includes a third P-type material, a fourth P-type material, and a third N-type material satisfying another preset energy level range.

Description

Technical Field

[0001] This disclosure relates to, but is not limited to, the field of display technology, and particularly to an organic electroluminescent device, a display substrate, and a display apparatus. Background Technology

[0002] Organic light-emitting devices (OLEDs) are active-matrix light-emitting devices with advantages such as light emission, ultra-thinness, wide viewing angle, high brightness, high contrast, low power consumption, and extremely fast response speed. They have gradually become a promising next-generation display technology. With the continuous development of OLED display technology, people's demands for the image quality of OLED products are also increasing. However, display panels suffer from the problem of display trailing. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0004] In a first aspect, embodiments of this disclosure provide an organic electroluminescent device, comprising: an anode, a cathode, and a light-emitting layer disposed between the anode and the cathode, wherein the material of the light-emitting layer includes a host material and a guest material; wherein the host material includes: a first host material or a second host material.

[0005] The first type of main material includes: a first P-type material, a first N-type material, a second P-type material, and a second N-type material, wherein the first P-type material, the first N-type material, the second P-type material, and the second N-type material satisfy the following:

[0006] 5.5eV≤│HOMO(PH1)│≤5.6eV, 2.4eV≤│LUMO(PH1)│≤2.5eV;

[0007] 6.1eV≤│HOMO(NH1)│≤6.2eV, 2.8eV≤│LUMO(NH1)│≤2.9eV;

[0008] 5.3eV≤│HOMO(PH2)│≤5.4eV, 2.2eV≤│LUMO(PH2)│≤2.3eV;

[0009] 5.9eV≤│HOMO(NH2)│≤6eV, 2.6eV≤│LUMO(NH2)│≤2.7eV;

[0010] Wherein, HOMO(PH1) is the highest occupied molecular orbital (HOMO) energy level of the first p-type material, LUMO(PH1) is the lowest unoccupied molecular orbital (LUMO) energy level of the first p-type material, HOMO(NH1) is the HOMO energy level of the first n-type material, LUMO(NH1) is the LUMO energy level of the first n-type material, HOMO(PH2) is the HOMO energy level of the second p-type material, LUMO(PH2) is the LUMO energy level of the second p-type material, HOMO(NH2) is the HOMO energy level of the second n-type material, and LUMO(NH2) is the LUMO energy level of the second n-type material.

[0011] The second type of main material includes: a third type P material, a fourth type P material, and a third type N material, wherein the third type P material, the fourth type P material, and the third type N material satisfy the following:

[0012] 5.5eV≤│HOMO(PH3-1)│≤5.6eV, 2.4eV≤│LUMO(PH3-1)│≤2.5eV;

[0013] 5.3eV≤│HOMO(PH3-2)│≤5.4eV, 2.2eV≤│LUMO(PH3-2)│≤2.3eV;

[0014] 6.1eV≤│HOMO(NH3)│≤6.2eV, 2.8eV≤│LUMO(NH3)│≤2.9eV;

[0015] Wherein, HOMO(PH3-1) is the HOMO energy level of the third P-type material, LUMO(PH3-1) is the LUMO energy level of the third P-type material, HOMO(PH3-2) is the HOMO energy level of the fourth P-type material, LUMO(PH3-2) is the LUMO energy level of the fourth P-type material, HOMO(NH3) is the HOMO energy level of the third N-type material, and LUMO(NH1) is the LUMO energy level of the third N-type material.

[0016] In some exemplary embodiments, the first type of main material includes: a first main material formed by mixing a first P-type material and a first N-type material, and a second main material formed by mixing a second P-type material and a second N-type material, wherein the weight ratio of the first main material and the second main material is 1:1.

[0017] In some exemplary embodiments, the light-emitting layer is formed by co-evaporation of the first host material, the second host material, and the guest material, wherein the concentration ratio of the first host material, the second host material, and the guest material is 48:48:4 to 45:45:10.

[0018] In some exemplary embodiments, the first body material is selected from any of the following:

[0019] The first P-type material is any one of carbazole compounds;

[0020] The first N-type material is any one of the triazine compounds or any one of the indolocarbazole compounds;

[0021] The second P-type material is any one of polycarbazole compounds or aromatic amine compounds;

[0022] The second N-type material is any one of the compounds that includes sterically hindered groups.

[0023] In some exemplary embodiments, the second type of main material is formed by ternary co-evaporation of a third P-type material, a fourth P-type material, and a third N-type material, wherein the concentration ratio between the sum of the concentrations of the third P-type material and the fourth P-type material and the concentration of the third N-type material is 6:4.

[0024] In some exemplary embodiments, the second host material is selected from any of the following: the third P-type material is any carbazole compound; the fourth P-type material is any polycarbazole compound or aromatic amine compound; the third N-type material is any triazine compound or indolecarbazole compound.

[0025] In some exemplary embodiments, the object material satisfies:

[0026] 5eV≤│HOMO(D)│≤5.1eV, 2.3eV≤│LUMO(D)│≤2.4eV; where HOMO(D) is the HOMO energy level of the guest material, and LUMO(D) is the LUMO energy level of the guest material.

[0027] In some exemplary embodiments, the guest material accounts for 4% to 10% of the doping ratio of the light-emitting layer.

[0028] In a second aspect, embodiments of this disclosure provide a display substrate, including: a substrate and a plurality of light-emitting devices disposed on one side of the substrate, wherein at least one of the plurality of light-emitting devices is an organic electroluminescent device as described in any of the exemplary embodiments above.

[0029] In some exemplary embodiments, the organic electroluminescent device is an organic electroluminescent device that emits green light.

[0030] Thirdly, embodiments of this disclosure provide a display device including a display substrate as described in the exemplary embodiments above.

[0031] The organic electroluminescent device, display substrate, and display device provided in this disclosure reduce the trap effect of the guest material by using P-type and N-type materials with different energy levels to form the host material, which is beneficial for releasing holes for recombination and light emission. This can increase the first frame ratio of the light-emitting device and effectively improve the problem of poor image ghosting.

[0032] Other features and advantages of this disclosure will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the disclosure. Other advantages of this disclosure may be realized and obtained by means of the embodiments described in the description and the accompanying drawings.

[0033] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0034] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this disclosure.

[0035] Figure 1 This is a schematic diagram of the structure of an OLED display device;

[0036] Figure 2 This is a schematic diagram of the planar structure of the display area of ​​a display substrate;

[0037] Figure 3 This is a schematic diagram of a cross-sectional structure of a display substrate;

[0038] Figure 4 This is a schematic diagram of the structure of an organic electroluminescent device according to an exemplary embodiment of the present disclosure;

[0039] Figure 5 This is a schematic diagram of the structure of a light-emitting device according to an exemplary embodiment of the present disclosure;

[0040] Figure 6 This is a schematic diagram of the structure of a comparative device in an exemplary embodiment of this disclosure;

[0041] Figure 7The graph shows the brightness ratio of the first frame for the disclosed device and the comparative device under different brightness levels.

[0042] Figure 8 This is a schematic diagram showing the exciton ratio results of device 2 under different current densities.

[0043] Figure 9 This is a schematic diagram of the structure of another light-emitting device in an exemplary embodiment of the present disclosure.

[0044] Explanation of reference numerals in the attached figures:

[0045] 101—Substrate; 102—Driving circuit layer; 103—Light-emitting structure layer;

[0046] 104—Packaging structure layer; 210—Transistor; 211—Storage capacitor;

[0047] 302—Pixel definition layer; 303—Organic light-emitting layer; 401—First encapsulation layer;

[0048] 402—Second encapsulation layer; 403—Third encapsulation layer; 501—Anode;

[0049] 502—Hole injection layer; 503—Hole transport layer; 504—Auxiliary emission layer;

[0050] 505—Emitting layer; 506—Hole blocking layer; 507—Electron transport layer;

[0051] 508—Electron injection layer; 509—Cathode. Detailed Implementation

[0052] This disclosure describes several embodiments, but these descriptions are exemplary and not limiting, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features 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 of any other embodiment, or may substitute for any other feature or element of any other embodiment.

[0053] This disclosure includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this disclosure may also be combined with any conventional features or elements to form unique inventive solutions. Any feature or element of any embodiment may also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this disclosure may be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.

[0054] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims relating to the method and / or process should not be limited to the steps performed in the order written, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments disclosed herein.

[0055] The scale of the figures in this disclosure can be used as a reference in actual manufacturing processes, but is not limited thereto. For example, the aspect ratio of the channel, the thickness and spacing of each film layer, and the width and spacing of each signal line can be adjusted according to actual needs. The number of pixels in the display substrate and the number of sub-pixels in each pixel are not limited to the quantities shown in the figures. The figures described in this disclosure are only schematic diagrams of the structure, and one aspect of this disclosure is not limited to the shapes or values ​​shown in the figures.

[0056] In the exemplary embodiments disclosed herein, ordinal numbers such as "first," "second," or "third," and similar terms, are used to avoid confusion among constituent elements, rather than to limit in terms of quantity, order, or importance. They should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of those features.

[0057] In the exemplary embodiments of this disclosure, for convenience, terms such as "center," "middle," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," or "circumferential" are used to describe the positional relationships of the constituent elements with reference to the accompanying drawings. This is solely for the purpose of facilitating the description of this disclosure and simplifying the description, and is not intended to indicate or imply that the device or element referred to has a specific orientation, or is constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this disclosure. The positional relationships of the constituent elements may be appropriately varied depending on the direction in which each constituent element is described. Therefore, the description is not limited to the terms used in the specification and may be appropriately replaced as appropriate.

[0058] In the exemplary embodiments disclosed herein, unless otherwise expressly specified and limited, the terms "installed," "connected," "linked," or "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art will understand the meaning of the above terms in this disclosure based on the actual situation.

[0059] In the embodiments of this disclosure, a transistor refers to a device that includes at least three terminals: a gate electrode (also referred to as the gate or control electrode), a drain electrode (also referred to as the drain terminal, drain region, or drain electrode), and a source electrode (also referred to as the source terminal, source region, or source electrode). The transistor has a channel region between the drain electrode and the source electrode, and current can flow through the drain electrode, the channel region, and the source electrode. Note that in this specification, the channel region refers to the region through which current primarily flows.

[0060] In the embodiments of this disclosure, to distinguish the two terminals of a transistor other than the control terminal, one terminal is directly described as the first terminal and the other as the second terminal. The first terminal can be the drain electrode and the second terminal can be the source electrode, or vice versa. In cases where transistors with opposite polarities are used or where the current direction changes during circuit operation, the functions of the "source electrode" and "drain electrode" are sometimes interchanged. Therefore, in this specification, the "source electrode" and "drain electrode" can be interchanged.

[0061] The transistors used in this disclosure can all be thin-film transistors (TFTs), field-effect transistors (FETs), or other devices with similar characteristics. For example, the thin-film transistors used in this disclosure can include, but are not limited to, oxide TFTs or low-temperature polysilicon TFTs (LTPS TFTs). For example, the thin-film transistor can be a bottom-gate structure thin-film transistor or a top-gate structure thin-film transistor, as long as it can achieve the switching function. Here, this disclosure does not limit this aspect.

[0062] In the embodiments of this disclosure, the term "about" refers to a value that is not strictly limited and is within the range of process and measurement errors.

[0063] In the embodiments of this disclosure, the term "stacked" may refer to multiple film layers being stacked along one direction, but does not necessarily mean that these film layers are necessarily bonded together in pairs.

[0064] In the embodiments of this disclosure, the expressions "on," "formed on," "set on," or similar expressions can indicate that one layer is directly formed or set on another layer, or that one layer is indirectly formed or set on another layer, meaning that there are other layers between the two layers. Furthermore, "above," "over," and "on top" of the first feature and the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" of the first feature and the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. In this document, unless otherwise stated, the term "located in the same layer" means that two layers, components, members, elements, or portions can be formed by the same patterning process, and that these two layers, components, members, elements, or portions are generally formed of the same material. In this document, unless otherwise stated, the expression "patterning process" generally includes steps such as photoresist coating, exposure, development, etching, and photoresist stripping. The expression "one-time patterning process" refers to a process of forming patterned layers, components, members, etc., using a single photomask.

[0065] In this embodiment of the disclosure, "thickness" refers to the height of the surface away from the substrate from the surface near the substrate in a plane perpendicular to the substrate.

[0066] The embodiments will now be described with reference to the accompanying drawings. These embodiments can be implemented in several different forms. Those skilled in the art will readily understand that the methods and content can be varied in different forms without departing from the spirit and scope of this disclosure. Therefore, this disclosure should not be construed as being limited to the content described in the following embodiments.

[0067] To keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of some known functions and components have been omitted. The accompanying drawings of the embodiments of this disclosure only relate to the structures involved in the embodiments of this disclosure; other structures can be referred to in general design.

[0068] Figure 1 This is a schematic diagram of the structure of a display device. Figure 1As shown, the 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, the scan driver, and the light-emitting driver. The data driver is connected to multiple data signal lines (D1 to Dn), the scan driver is connected to multiple scan signal lines (S1 to Sm), and the light-emitting driver is connected to multiple light-emitting signal lines (E1 to Eo). The pixel array may include multiple sub-pixels Pxij, where i and j can be natural numbers. At least one sub-pixel Pxij may include a circuit unit and a light-emitting device connected to the circuit unit. The circuit unit may include a pixel driving circuit, which may be connected to the scan signal lines, the light-emitting signal lines, and the data signal lines. In some exemplary embodiments, the timing controller may provide grayscale values ​​and control signals of specifications suitable for the data driver to the data driver, provide clock signals, scan start signals, etc. of specifications suitable for the scan driver to the scan driver, and provide clock signals, transmit stop signals, etc. of specifications suitable for the light-emitting driver to the light-emitting driver. The data driver can use grayscale values ​​and control signals received from the timing controller to generate data voltages to be provided to data signal lines D1, D2, D3, ..., Dn, where n can be a natural number. For example, the data driver can sample grayscale values ​​using a clock signal and apply the data voltage corresponding to the grayscale value to data signal lines D1 to Dn on a pixel-by-pixel basis. The scan driver can receive clock signals, scan start signals, etc., from the timing controller to generate scan signals to be provided to scan signal lines S1, S2, S3, ..., Sm, where m can be a natural number. For example, the scan driver can sequentially provide scan signals with on-level pulses to scan signal lines S1 to Sm. For example, the scan driver can be configured as a shift register and can generate scan signals by sequentially transmitting scan start signals in the form of on-level pulses to the next stage circuit under the control of a clock signal. The light-emitting driver can receive clock signals, transmit stop signals, etc., from the timing controller to generate transmit signals to light-emitting signal lines E1, E2, E3, ..., Eo, where o can be a natural number. For example, an LED driver can sequentially provide transmit signals with cutoff level pulses to LED signal lines E1 to Eo. For example, the LED driver can be configured as a shift register and can generate transmit signals by sequentially transmitting transmit stop signals in the form of cutoff level pulses to the next stage circuit under the control of a clock signal.

[0069] Figure 2 This is a schematic diagram of a planar structure of a display substrate. Figure 2As shown, the display substrate may include multiple pixel units P arranged in a regular pattern (e.g., 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 device connected to the circuit unit. The circuit unit may include a pixel driving circuit and scan signal lines, data signal lines, and light-emitting signal lines connected to the pixel driving circuit. The pixel driving circuit is configured to receive the data voltage transmitted by the data signal line and output a corresponding current to the light-emitting device under the control of the scan signal line and the light-emitting signal line. The light-emitting device in each sub-pixel is connected to the pixel driving circuit of its respective sub-pixel, and the light-emitting device is configured to emit light of a corresponding brightness in response to the current output by the pixel driving circuit of its respective sub-pixel.

[0070] In some exemplary embodiments, a pixel unit P may include red (R) sub-pixels, green (G) sub-pixels, and blue (B) sub-pixels, or it may include red, green, blue, and white sub-pixels; this disclosure does not limit the scope of the invention. In some exemplary embodiments, the shape of the sub-pixels in a pixel unit may be rectangular, rhomboid, pentagonal, or hexagonal, etc. In some exemplary embodiments, when a pixel unit includes three sub-pixels, the three sub-pixels may be arranged horizontally side-by-side, vertically side-by-side, or in a triangular arrangement. In other exemplary embodiments, when a pixel unit includes four sub-pixels, the four sub-pixels may be arranged horizontally side-by-side, vertically side-by-side, or in a square arrangement; this disclosure does not limit the scope of the invention.

[0071] Figure 3 This is a cross-sectional structural diagram of a display substrate, illustrating the structure of three sub-pixels in an OLED display substrate. Figure 3 As shown, on a plane perpendicular to the display substrate, the display substrate may include a driving circuit layer 102 disposed on the substrate 101, a light-emitting structure layer 103 disposed on the side of the driving circuit layer 102 away from the substrate 101, and an encapsulation structure layer 104 disposed on the side of the light-emitting structure layer 103 away from the substrate 101. In some possible implementations, the display substrate may include other film layers, such as a touch structure layer, etc., which are not limited herein.

[0072] In some exemplary embodiments, the substrate 101 may be a flexible substrate or a rigid substrate.

[0073] In some exemplary embodiments, the driving circuit layer 102 for each sub-pixel may include a plurality of transistors and a storage capacitor constituting a pixel driving circuit. Figure 3The example only uses one transistor 210 and one storage capacitor 211. In some exemplary embodiments, the light-emitting structure layer 103 may include an anode 501, a pixel definition layer 302, an organic light-emitting layer 303, and a cathode 505. The anode 501 is connected to the drain electrode of the driving transistor 210 through a via. The pixel definition layer 302 is provided with a pixel opening that exposes the anode 501. The organic light-emitting layer 303 is connected to the anode 501, and the cathode 505 is connected to the organic light-emitting layer 303. The organic light-emitting layer 303 emits light of the corresponding color under the drive of the anode 501 and the cathode 505.

[0074] In some exemplary embodiments, the organic light-emitting layer 303 may include an emitting layer (EML) and one or more of the following film layers: a hole injection layer (HIL), a hole transport layer (HTL), an electron block layer (EBL), a hole block layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL). The emitting layer is configured to emit light by recombination of electrons and holes. The hole injection layer is configured to lower the potential barrier for injecting holes from the anode, allowing holes to be effectively injected from the anode into the emitting layer. The hole transport layer is configured to achieve directional and controlled migration of injected holes. The electron block layer is configured to form a migration barrier for electrons, preventing electrons from migrating out of the emitting layer. The hole block layer is configured to form a migration barrier for holes, preventing holes from migrating out of the emitting layer. The electron transport layer is configured to enable the directional and orderly controlled migration of injected electrons. The electron injection layer is configured to lower the potential barrier for electrons injected from the cathode, allowing electrons to be efficiently injected from the cathode into the light-emitting layer. In some exemplary embodiments, one or more of the hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer, and electron injection layer of all sub-pixels may be common layers connected together, and the light-emitting layers of adjacent sub-pixels may have a small overlap or may be isolated. For example, to reduce fabrication complexity and improve yield, the hole injection layer and hole transport layer on one side of the light-emitting layer may be common layers, and the electron injection layer and electron transport layer on the other side of the light-emitting layer may also be common layers.

[0075] In some exemplary embodiments, the light-emitting layers of OLED light-emitting elements of different colors are different. For example, a red light-emitting device includes a red light-emitting layer, a green light-emitting device includes a green light-emitting layer, and a blue light-emitting device includes a blue light-emitting layer. In some exemplary embodiments, the organic light-emitting layer can be formed by vapor deposition using a fine metal mask (FMM) or an open mask, or by inkjet printing.

[0076] In some exemplary embodiments, the light-emitting layer material may include a host material and a dopant material (also known as a guest material). A green light-emitting layer (GEML) may include a green host material (GH) and a green guest material (GH) doped in the green host material; a red light-emitting layer (REML) may include a red host material (RH) and a red guest material (RH) doped in the red host material; a blue light-emitting layer (BEML) may include a blue host material (BH) and a blue guest material (BH) doped in the blue host material.

[0077] In some exemplary embodiments, the encapsulation structure layer 104 may include a first encapsulation layer 401, a second encapsulation layer 402, and a third encapsulation layer 403 stacked together. For example, the first encapsulation layer 401 and the third encapsulation layer 403 may be made of inorganic materials, while the second encapsulation layer 402 may be made of organic materials. The second encapsulation layer 402 is disposed between the first encapsulation layer 401 and the third encapsulation layer 403 to ensure that external moisture cannot enter the light-emitting structure layer 103.

[0078] In some exemplary embodiments, the pixel driving circuit may employ a pixel circuit with an nTmC (n and m are positive integers) structure, such as 2T1C (i.e., two transistors and one capacitor), 3T1C, 4T1C, 5T1C, 5T2C, 6T1C, 7T1C, or 8T1C. In different exemplary embodiments, the pixel circuit may further include a compensation sub-circuit, which may include an internal or external compensation sub-circuit, and may include transistors, capacitors, etc. For example, as needed, the pixel circuit may also include a reset sub-circuit, a light emission control sub-circuit, etc. This disclosure does not limit this aspect.

[0079] In current OLED display panels, due to the limitations of driving circuits and components, a common issue arises when the displayed image transitions from low to high grayscale: the brightness of the first frame of the high grayscale image is lower than the normal brightness. This results in a display trailing effect, leading to poor display quality and a less than ideal visual experience for the user. For example, when switching from black to white, the brightness of the first white frame is lower than the normal brightness, causing a ghosting effect on the white image, which is particularly noticeable in the first frame where green light has a small proportion. Improving this display trailing problem remains to be solved.

[0080] Among them, display trailing (also known as display ghosting) refers to the effect of afterimages or blurring in fast-moving images or scenes.

[0081] This exemplary embodiment provides an organic electroluminescent device that uses P-type and N-type materials of different energy levels to form the host material, reducing the trap effect of the guest material. This facilitates the release of holes for recombination and light emission, increasing the first-frame ratio of the light-emitting device and effectively improving the problem of image ghosting. Here, a trap refers to a crystal defect or physical center capable of trapping electrons or holes.

[0082] An exemplary embodiment of this disclosure provides an organic electroluminescent device, which may include: an anode, a cathode, and a light-emitting layer disposed between the anode and the cathode. The material of the light-emitting layer may include a host material and a guest material; the host material may include: a first host material or a second host material, wherein...

[0083] The first type of main material may include: a first P-type material, a first N-type material, a second P-type material, and a second N-type material. The first P-type material, the first N-type material, the second P-type material, and the second N-type material can satisfy the following:

[0084] 5.5eV≤│HOMO(PH1)│≤5.6eV, 2.4eV≤│LUMO(PH1)│≤2.5eV;

[0085] 6.1eV≤│HOMO(NH1)│≤6.2eV, 2.8eV≤│LUMO(NH1)│≤2.9eV;

[0086] 5.3eV≤│HOMO(PH2)│≤5.4eV, 2.2eV≤│LUMO(PH2)│≤2.3eV;

[0087] 5.9eV≤│HOMO(NH2)│≤6eV, 2.6eV≤│LUMO(NH2)│≤2.7eV;

[0088] Among them, HOMO(PH1) is the highest occupied molecular orbital HOMO energy level of the first p-type material, LUMO(PH1) is the lowest unoccupied molecular orbital LUMO energy level of the first p-type material, HOMO(NH1) is the HOMO energy level of the first n-type material, LUMO(NH1) is the LUMO energy level of the first n-type material, HOMO(PH2) is the HOMO energy level of the second p-type material, LUMO(PH2) is the LUMO energy level of the second p-type material, HOMO(NH2) is the HOMO energy level of the second n-type material, and LUMO(NH2) is the LUMO energy level of the second n-type material.

[0089] The second type of main material may include: a third type P material, a fourth type P material, and a third type N material. The third type P material, the fourth type P material, and the third type N material can satisfy the following:

[0090] 5.5eV≤│HOMO(PH3-1)│≤5.6eV, 2.4eV≤│LUMO(PH3-1)│≤2.5eV;

[0091] 5.3eV≤│HOMO(PH3-2)│≤5.4eV, 2.2eV≤│LUMO(PH3-2)│≤2.3eV;

[0092] 6.1eV≤│HOMO(NH3)│≤6.2eV, 2.8eV≤│LUMO(NH3)│≤2.9eV;

[0093] Among them, HOMO(PH3-1) is the HOMO energy level of the third P-type material, LUMO(PH3-1) is the LUMO energy level of the third P-type material, HOMO(PH3-2) is the HOMO energy level of the fourth P-type material, LUMO(PH3-2) is the LUMO energy level of the fourth P-type material, HOMO(NH3) is the HOMO energy level of the third N-type material, and LUMO(NH1) is the LUMO energy level of the third N-type material.

[0094] In some exemplary embodiments, the first host material may include: a first host material H1 formed by mixing a first P-type material and a first N-type material, and a second host material H2 formed by mixing a second P-type material and a second N-type material, wherein the weight ratio of the first host material H1 and the second host material H2 may be approximately 1:1.

[0095] In some exemplary embodiments, the first body material may be selected from any of the following:

[0096] The first type P material can be any of the carbazole compounds;

[0097] The first type N material can be any of the triazine compounds or any of the indolocarbazole compounds;

[0098] The second P-type material can be any one of polycarbazole compounds or aromatic amine compounds;

[0099] The second type N material can be any of the compounds that include sterically hindered groups.

[0100] In some exemplary embodiments, the light-emitting layer is formed by co-evaporation of a first host material, a second host material, and a guest material, and the concentration ratio of the first host material, the second host material, and the guest material can be approximately 48:48:4 to 45:45:10.

[0101] In some exemplary embodiments, the second host material may be formed by ternary co-evaporation of a third P-type material, a fourth P-type material, and a third N-type material, and the concentration ratio between the sum of the concentrations of the third P-type material and the fourth P-type material and the concentration of the third N-type material may be approximately 6:4.

[0102] In some exemplary embodiments, the second body material may be selected from any of the following:

[0103] The third type P material can be any of the carbazole compounds;

[0104] The fourth type P material can be any one of polycarbazole compounds or aromatic amine compounds;

[0105] The third type N material can be any of the triazine compounds or any of the indolcarbazole compounds.

[0106] In some exemplary embodiments, the object material may satisfy:

[0107] 5eV≤│HOMO(D)│≤5.1eV, 2.3eV≤│LUMO(D)│≤2.4eV;

[0108] Wherein, HOMO(D) is the HOMO energy level of the guest material, and LUMO(D) is the LUMO energy level of the guest material.

[0109] In some exemplary embodiments, the doping ratio of the guest material in the light-emitting layer can be approximately 4% to 10%.

[0110] Figure 4 This is a schematic diagram of the structure of an organic electroluminescent device according to an exemplary embodiment of this disclosure. Figure 4As shown, an exemplary embodiment of this disclosure provides an organic electroluminescent device, which may include: an anode 501, a cathode 509, and a light-emitting layer 505 disposed between the anode 501 and the cathode 509. The organic electroluminescent device may further include: a hole injection layer 502 disposed on the side of the anode 501 near the light-emitting layer 505, a hole transport layer 503 disposed on the side of the hole injection layer 502 near the light-emitting layer 505, and an auxiliary light-emitting layer 504 disposed on the side of the hole transport layer 503 near the light-emitting layer 505. The organic electroluminescent device may further include: an electron injection layer 508 disposed on the side of the cathode 509 near the light-emitting layer 505, an electron transport layer 507 disposed on the side of the electron injection layer 508 near the light-emitting layer 505, and a hole blocking layer 506 disposed on the side of the electron transport layer 507 near the light-emitting layer 505. The hole injection layer 502 is configured to lower the potential barrier for holes injected from the anode 501, allowing holes to be effectively injected from the anode 501 into the light-emitting layer 50. Hole transport layer 503 is configured to achieve controlled, directional migration of injected holes. Auxiliary light-emitting layer 504 is configured to form a migration barrier for electrons, preventing electrons from migrating out of light-emitting layer 505. Light-emitting layer 505 is configured to cause recombination between electrons and holes to emit light. Hole blocking layer 506 is configured to form a migration barrier for holes, preventing holes from migrating out of light-emitting layer 505. Electron transport layer 507 is configured to achieve controlled, directional migration of injected electrons. Electron injection layer 508 is configured to lower the barrier for electrons injected from cathode 509, allowing electrons to be effectively injected from cathode 509 into light-emitting layer 50.

[0111] The light-emitting process of an OLED device can be described as follows: Under the drive of a low-voltage DC high electric field, holes are injected from the anode into the organic layer sandwiched between the two electrodes, and electrons are injected from the cathode into the organic layer sandwiched between the two electrodes; the injected holes migrate from the hole transport layer to the light-emitting layer, and the electrons migrate from the electron transport layer to the light-emitting layer; the holes and electrons meet in the light-emitting layer and generate excitons, which transfer energy to the organic light-emitting molecules under the action of the electric field and excite the electrons in the organic molecules to transition from the ground state to the excited state. The energy of the excited state is released in the form of photons through the transition, generating light energy.

[0112] In some exemplary embodiments, the light-emitting layer 505 may include a host material H and a guest material D. The host material H may include a first host material H1 and a second host material H2. Both the first host material H1 and the second host material H2 may be dual host materials, i.e., premixed materials composed of a mixture of P-type and N-type materials. A dual host material refers to a host material that simultaneously contains both P-type (also known as a hole-type material) and N-type (also known as an electron-type material). For example, the first host material H1 may include a mixture of a first P-type material and a first N-type material, and the second host material H2 may include a mixture of a second P-type material and a second N-type material.

[0113] In some exemplary embodiments, the first N-type material in the first body material H1 satisfies:

[0114] 6.1eV≤│HOMO(NH1)│≤6.2eV, 2.8eV≤│LUMO(NH1)│≤2.9eV;

[0115] Wherein, HOMO(NH1) is the highest occupied molecular orbital HOMO energy level of the first N-type material in the first host material H1, and LUMO(NH1) is the lowest unoccupied molecular orbital LUMO energy level of the first N-type material in the first host material H1.

[0116] In some exemplary embodiments, the HOMO energy level of the first N-type material of the first host material H1 can be any value from approximately -6.2 eV to -6.1 eV. For example, the HOMO energy level of the first N-type material of the first host material H1 can be approximately -6.2 eV, -6.15 eV, or -6.1 eV, etc. The LUMO energy level of the first N-type material of the first host material H1 can be any value from approximately -2.9 eV to -2.8 eV. For example, the LUMO energy level of the first N-type material of the first host material H1 can be approximately -2.9 eV, -2.85 eV, or -2.8 eV (electron volts), etc. Here, the embodiments of this disclosure do not specifically limit this.

[0117] In some exemplary embodiments, the first P-type material in the first body material H1 satisfies:

[0118] 5.5eV≤│HOMO(PH1)│≤5.6eV, 2.4eV≤│LUMO(PH1)│≤2.5eV;

[0119] Wherein, HOMO(PH1) is the highest occupied molecular orbital HOMO energy level of the first p-type material in the first host material H1, and LUMO(PH1) is the lowest unoccupied molecular orbital LUMO energy level of the first p-type material in the first host material H1.

[0120] In some exemplary embodiments, the HOMO energy level of the first P-type material of the first host material H1 can be any value from approximately -5.6 eV to -5.5 eV. For example, the HOMO energy level of the first P-type material of the first host material H1 can be approximately -5.6 eV, -5.55 eV, or -5.5 eV, etc. The LUMO energy level of the first P-type material of the first host material H1 can be any value from approximately -2.5 eV to -2.4 eV. For example, the LUMO energy level of the first P-type material of the first host material H1 can be approximately -2.5 eV, -2.45 eV, or -2.4 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0121] In some exemplary embodiments, the first P-type material and the first N-type material in the first host material H1 can be selected from materials whose HOMO and LUMO energy levels are within the above range, that is, the first host material H1 can be a green light host material.

[0122] In some exemplary embodiments, the first P-type material in the first host material H1 can be a P-type monomer material, for example, the first P-type material can be any of the carbazole compounds. For example, the first P-type material can be selected from any of the following carbazole-containing materials: 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP), 9,9'-(1,3-phenyl)bis-9H-carbazole (mCP), 2,2'-bis(4-carbazolylphenyl)biphenyl (BCBP). Thus, the HOMO energy level can be adjusted by changing the substitution position, etc. Among them, carbazole compounds include a carbazole ring, which is formed by the fusion of two benzene rings and a five-membered pyrrole ring.

[0123] In some exemplary embodiments, the first N-type material in the first host material H1 is an N-type monomer material. For example, the first N-type material can be any of the triazine compounds or any of the indobenzocarbazole compounds. The triazine compounds include a triazine ring, which is a six-membered ring containing three carbon atoms and three nitrogen atoms; the indobenzocarbazole compounds include an indole ring and a carbazole ring. The indole ring is a six-membered aromatic ring (benzene ring) fused with a five-membered nitrogen-containing pyrrole ring, and the carbazole ring is two benzene rings fused with a pyrrole ring.

[0124] For example, taking the first N-type material as a triazine compound, the first N-type material can be: 2,4,6-tris(1,1'-biphenyl)-1,3,5-triazine (2,4,6-Tris(biphenyl-3-yl)-1,3,5-triazine, abbreviated as T2T) material.

[0125] For example, taking the first N-type material as an indole-carbazole compound, the first N-type material can be selected from any of the compounds shown in formula (1-1) and formula (1-2):

[0126]

[0127] In some exemplary embodiments, the second N-type material in the second body material H2 satisfies:

[0128] 5.9eV≤│HOMO(NH2)│≤6eV, 2.6eV≤│LUMO(NH2)│≤2.7eV;

[0129] Among them, HOMO(NH2) is the highest occupied molecular orbital HOMO energy level of the second N-type material in the second host material H2, and LUMO(NH2) is the lowest unoccupied molecular orbital LUMO energy level of the second N-type material in the second host material H2.

[0130] Thus, the HOMO energy level of the second N-type material in the second host material H2 can be any value from approximately -6 eV to -5.9 eV. For example, the HOMO energy level of the second N-type material in the second host material H2 can be approximately -6 eV, -5.95 eV, or -5.9 eV, etc. The LUMO energy level of the second N-type material in the second host material H2 can be any value from approximately -2.7 eV to -2.6 eV. For example, the LUMO energy level of the second N-type material in the second host material H2 can be approximately -2.7 eV, -2.65 eV, or -2.6 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0131] In some exemplary embodiments, the second P-type material in the second body material H2 satisfies:

[0132] 5.3eV≤│HOMO(PH2)│≤5.4eV, 2.2eV≤│LUMO(PH2)│≤2.3eV;

[0133] Among them, HOMO(PH2) is the highest occupied molecular orbital HOMO energy level of the second p-type material in the second host material H2, and LUMO(PH2) is the lowest unoccupied molecular orbital LUMO energy level of the second p-type material in the second host material H2.

[0134] Thus, the HOMO energy level of the second p-type material of the second host material H2 can be any value from approximately -5.4 eV to -5.3 eV. For example, the HOMO energy level of the second p-type material of the second host material H2 can be approximately -5.4 eV, -5.35 eV, or -5.3 eV, etc. The LUMO energy level of the second p-type material of the second host material H2 can be any value from approximately -2.3 eV to -2.2 eV. For example, the LUMO energy level of the second p-type material of the second host material H2 can be approximately -2.3 eV, -2.25 eV, or -2.2 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0135] In some exemplary embodiments, the second P-type material and the second N-type material in the second host material H2 can be selected from materials whose HOMO and LUMO energy levels are within the above range, that is, the second host material H2 can be a green light host material.

[0136] In some exemplary embodiments, the second P-type material in the second host material H2 can be a P-type monomer material. For example, the second P-type material in the second host material H2 can be any one of a polycarbazole compound or an aromatic amine compound. Here, a polycarbazole compound refers to a compound containing multiple carbazole rings, and an aromatic amine compound refers to a compound containing an aromatic amine group.

[0137] In some exemplary embodiments, the second P-type material may be selected from any of the following compounds: 4,4',4”-tris(carbazol-9-yl)triphenylamine (TCTA), 1,3,5-tris(9-carbazolyl)benzene (TCP), 3,6-bis(9-phenyl-9H-carbazol-3-yl)-9-phenyl-9H-carbazole (Tris-PCZ), etc.

[0138] Thus, by introducing electron-donating groups (such as polycarbazole groups or aromatic amine groups) into the second P-type material in the second host material H2, conjugation can be increased, thereby making the HOMO of the second P-type material shallower.

[0139] In some exemplary embodiments, the second N-type material in the second host material H2 can be an N-type monomer material. For example, the second N-type material in the second host material H2 can be any of the compounds that include sterically hindered groups. The sterically hindered groups can be selected from any of the following groups: alkyl groups with 1 to 20 carbon atoms (such as methyl, ethyl, isopropyl, etc.), aryl groups with 6 to 60 carbon atoms (such as phenyl, naphthyl, etc.), and other bulky groups (such as tert-butyl, triphenylmethyl, etc.).

[0140] For example, the second N-type material can be selected from any of the compounds shown in formulas (2-1) and (2-2):

[0141]

[0142] Thus, by adding steric hindrance groups with larger volumes or more complex spatial structures to the second N-type material in the second host material H2, conjugation can be reduced, thereby making the LUMO of the second N-type material shallower by changing the substitution position and other means.

[0143] In some exemplary embodiments, the weight ratio of the first body material H1 and the second body material H2 is approximately 1:1.

[0144] In some exemplary embodiments, the first P-type material accounts for approximately 50% to 65% of the weight of the first main material H1, and the first N-type material accounts for approximately 50% to 35% of the weight of the first main material H1. For example, the first P-type material accounts for approximately 50% of the weight of the first main material H1, and the first N-type material accounts for approximately 50% of the weight of the first main material H1; or, the first P-type material accounts for approximately 55% of the weight of the first main material H1, and the first N-type material accounts for approximately 45% of the weight of the first main material H1; or, the first P-type material accounts for approximately 60% of the weight of the first main material H1, and the first N-type material accounts for approximately 40% of the weight of the first main material H1; or, the first P-type material accounts for approximately 65% ​​of the weight of the first main material H1, and the first N-type material accounts for approximately 35% of the weight of the first main material H1, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0145] In some exemplary embodiments, the weight ratio of the first P-type material to the first N-type material in the first body material H1 is approximately 5:5 to 6.5:3.5. For example, the weight ratio of the first P-type material to the first N-type material is approximately 5:5, or approximately 5.5:4.5, or approximately 6:4, or approximately 6.5:3.5, etc. This disclosure does not specifically limit the specific ratio in this regard.

[0146] In some exemplary embodiments, the second P-type material accounts for approximately 50% to 65% of the weight of the second main material H2, and the second N-type material accounts for approximately 50% to 35% of the weight of the second main material H2. For example, the second P-type material accounts for approximately 50% of the weight of the second main material H2, and the second N-type material accounts for approximately 50% of the weight of the second main material H2; or, the second P-type material accounts for approximately 55% of the weight of the second main material H2, and the second N-type material accounts for approximately 45% of the weight of the second main material H2; or, the second P-type material accounts for approximately 60% of the weight of the second main material H1, and the second N-type material accounts for approximately 40% of the weight of the second main material H2; or, the second P-type material accounts for approximately 65% ​​of the weight of the second main material H2, and the second N-type material accounts for approximately 35% of the weight of the second main material H1, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0147] In some exemplary embodiments, the weight ratio of the second P-type material and the second N-type material in the second body material H2 can be approximately 5:5 to 6.5:3.5. For example, the weight ratio of the second P-type material and the second N-type material can be approximately 5:5, or approximately 5.5:4.5, or approximately 6:4, or approximately 6.5:3.5, etc. This disclosure does not specifically limit the ratio in this regard.

[0148] Thus, by setting the HOMO and LUMO energy levels of the first N-type material and the first P-type material in the first host material H1 to satisfy the above range, and setting the HOMO and LUMO energy levels of the second N-type material and the second P-type material in the second host material H2 to satisfy the above range, the energy level ladder formed by H1 / H2 is beneficial to overcoming the energy level barrier, reducing the trap effect of the guest material, and releasing holes for recombination luminescence, thereby improving the brightness of the first frame.

[0149] In some other exemplary embodiments, the first host material H1 may include a mixture of a first P-type material and a first N-type material, wherein the first P-type material and the first N-type material in the first host material H1 satisfy the following:

[0150] 0.5eV≤│HOMO(NH1)-HOMO(PH1)│≤0.7eV;

[0151] 0.3eV≤│LUMO(NH1)-LUMO(PH1)│≤0.5eV;

[0152] Wherein, HOMO(NH1) is the highest occupied molecular orbital HOMO energy level of the first N-type material in the first host material H1, HOMO(PH1) is the highest occupied molecular orbital HOMO energy level of the first P-type material in the first host material H1, LUMO(NH1) is the lowest unoccupied molecular orbital LUMO energy level of the first N-type material in the first host material H1, and LUMO(PH1) is the lowest unoccupied molecular orbital LUMO energy level of the first P-type material in the first host material H1.

[0153] Here, the absolute value of the difference between the HOMO energy level of the first N-type material and the HOMO energy level of the first P-type material in the first host material H1 is greater than or equal to 0.5 eV. This can be: the difference between the HOMO energy level of the first N-type material and the HOMO energy level of the first P-type material in the first host material H1 is greater than or equal to 0.5 eV, in which case the HOMO energy level of the first N-type material in the first host material H1 is greater than the HOMO energy level of the first P-type material; or, the difference between the HOMO energy level of the first N-type material and the HOMO energy level of the first P-type material in the first host material H1 is less than -0.5 eV, in which case the HOMO energy level of the first N-type material in the first host material H1 is less than the HOMO energy level of the first P-type material. Similarly, the absolute value of the difference between the HOMO energy level of the first N-type material and the HOMO energy level of the first P-type material in the first host material H1 is less than or equal to 0.7 eV, which can be understood with reference to the above content and will not be repeated here.

[0154] Similarly, if the absolute value of the difference between the LUMO energy level of the first N-type material and the LUMO energy level of the first P-type material in the first host material H1 is greater than or equal to 0.3 eV, it can be that: the difference between the LUMO energy level of the first N-type material and the LUMO energy level of the first P-type material in the first host material H1 is greater than or equal to 0.3 eV, in which case the LUMO energy level of the first N-type material in the first host material H1 is greater than the LUMO energy level of the first P-type material; or, the difference between the LUMO energy level of the first N-type material and the LUMO energy level of the first P-type material in the first host material H1 is less than -0.3 eV, in which case the LUMO energy level of the first N-type material in the first host material H1 is less than the LUMO energy level of the first P-type material. Similarly, if the absolute value of the difference between the LUMO energy level of the first N-type material and the LUMO energy level of the first P-type material in the first host material H1 is less than or equal to 0.5 eV, this can be understood with reference to the above content and will not be repeated here.

[0155] In some other exemplary embodiments, the second host material H2 may include: a mixture of a second P-type material and a second N-type material, wherein the second P-type material and the second N-type material in the second host material H2 satisfy the following:

[0156] 0.5eV≤│HOMO(NH2)-HOMO(PH2)│≤0.7eV;

[0157] 0.3eV≤│LUMO(NH2)-LUMO(PH2)│≤0.5eV;

[0158] Among them, HOMO(NH2) is the highest occupied molecular orbital HOMO energy level of the second N-type material in the second host material H2, HOMO(PH2) is the highest occupied molecular orbital HOMO energy level of the second P-type material in the second host material H2, LUMO(NH2) is the lowest unoccupied molecular orbital LUMO energy level of the second N-type material in the second host material H2, and LUMO(PH2) is the lowest unoccupied molecular orbital LUMO energy level of the second P-type material in the second host material H2.

[0159] Here, the absolute value of the difference between the HOMO energy levels of the second N-type material and the second P-type material in the second host material H2 is greater than or equal to 0.5 eV. This can be interpreted as follows: if the difference is greater than or equal to 0.5 eV, then the HOMO energy level of the second N-type material in the second host material H2 is greater than the HOMO energy level of the second P-type material; or, if the difference is less than -0.5 eV, then the HOMO energy level of the second N-type material in the second host material H2 is less than the HOMO energy level of the second P-type material. Similarly, the absolute value of the difference between the HOMO energy levels of the second N-type material and the second P-type material in the second host material H2 is less than or equal to 0.7 eV, which can be understood with reference to the above content and will not be elaborated further here.

[0160] Similarly, if the absolute value of the difference between the LUMO energy level of the second N-type material and the LUMO energy level of the second P-type material in the second host material H2 is greater than or equal to 0.3 eV, it can be that: the difference between the LUMO energy level of the second N-type material and the LUMO energy level of the second P-type material in the second host material H2 is greater than or equal to 0.3 eV, in which case the LUMO energy level of the second N-type material in the second host material H2 is greater than the LUMO energy level of the second P-type material; or, the difference between the LUMO energy level of the second N-type material and the LUMO energy level of the second P-type material in the second host material H2 is less than -0.3 eV, in which case the LUMO energy level of the second N-type material in the second host material H2 is less than the LUMO energy level of the second P-type material. Similarly, if the absolute value of the difference between the LUMO energy level of the second N-type material and the LUMO energy level of the second P-type material in the second host material H2 is less than or equal to 0.5 eV, this can be understood with reference to the above content and will not be repeated here.

[0161] Thus, by setting the absolute value of the difference between the HOMO energy level of the N-type material and the HOMO energy level of the P-type material in the first host material H1 to be no less than 0.5 eV and no more than 0.7 eV, and the absolute value of the difference between the LUMO energy level of the N-type material and the LUMO energy level of the P-type material in the first host material H1 to be no less than 0.3 eV and no more than 0.5 eV, and setting the absolute value of the difference between the HOMO energy level of the N-type material and the HOMO energy level of the P-type material in the second host material H2 to be no less than 0.5 eV and no more than 0.7 eV, and the absolute value of the difference between the LUMO energy level of the N-type material and the LUMO energy level of the P-type material in the second host material H2 to be no less than 0.3 eV and no more than 0.5 eV, the energy level ladder formed by H1 / H2 is beneficial for overcoming the energy level barrier, reducing the trap effect of the guest material D, and releasing holes for recombination luminescence, thereby improving the brightness of the first frame.

[0162] In some other exemplary embodiments, the light-emitting layer 505 may include a host material H and a guest material D. The host material H may include a third host material H3, which may include a third P-type material, a fourth P-type material, and a third N-type material.

[0163] In some exemplary embodiments, the third P-type material in the third host material H3 can satisfy: 5.5eV≤│HOMO(PH3-1)│≤5.6eV, 2.4eV≤│LUMO(PH3-1)│≤2.5eV;

[0164] Among them, HOMO(PH3-1) is the highest occupied molecular orbital HOMO energy level of the third p-type material in the third host material H3, and LUMO(PH3-1) is the lowest unoccupied molecular orbital LUMO energy level of the third p-type material in the third host material H3.

[0165] Thus, the HOMO energy level of the third P-type material in the third host material H3 can be any value from approximately -5.6 eV to -5.5 eV. For example, the HOMO energy level of the third P-type material in the third host material H3 can be approximately -5.6 eV, -5.55 eV, or -5.5 eV, etc. The LUMO energy level of the third P-type material in the third host material H3 can be any value from approximately -2.5 eV to -2.4 eV. For example, the LUMO energy level of the third P-type material in the third host material H3 can be approximately -2.5 eV, -2.45 eV, or -2.4 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0166] In some exemplary embodiments, the fourth P-type material in the third host material H3 satisfies: 5.3eV≤│HOMO(PH3-2)│≤5.4eV, 2.2eV≤│LUMO(PH3-2)│≤2.3eV; wherein, HOMO(PH3-2) is the highest occupied molecular orbital HOMO energy level of the fourth P-type material in the third host material H3, and LUMO(PH3-2) is the lowest unoccupied molecular orbital LUMO energy level of the fourth P-type material in the third host material H3.

[0167] Thus, the HOMO energy level of the fourth P-type material in the third host material H3 can be any value between approximately -5.4 eV and -5.3 eV. For example, the HOMO energy level of the fourth P-type material in the third host material H3 can be approximately -5.4 eV, -5.35 eV, or -5.3 eV, etc. The LUMO energy level of the fourth P-type material in the third host material H3 can be any value between approximately -2.3 eV and -2.2 eV. For example, the LUMO energy level of the fourth P-type material in the third host material H3 can be approximately -2.3 eV, -2.25 eV, or -2.2 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0168] In some exemplary embodiments, the third N-type material in the third host material H3 can satisfy: 6.1eV≤│HOMO(NH3)│≤6.2eV, 2.8eV≤│LUMO(NH3)│≤2.9eV; wherein, HOMO(NH3) is the highest occupied molecular orbital HOMO energy level of the third N-type material in the third host material H3, and LUMO(NH1) is the lowest unoccupied molecular orbital LUMO energy level of the third N-type material in the third host material H3.

[0169] Thus, the HOMO energy level of the third N-type material in the third host material H3 can be any value from -6.2 eV to -6.1 eV. For example, the HOMO energy level of the third N-type material in the third host material H3 can be -6.2 eV, -6.15 eV, or -6.1 eV, etc. The LUMO energy level of the third N-type material in the third host material H3 can be any value from -2.9 eV to -2.8 eV. For example, the LUMO energy level of the third N-type material in the third host material H3 can be -2.9 eV, -2.85 eV, or -2.8 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0170] In some exemplary embodiments, the third P-type material in the third host material H3 can be any of the carbazole compounds. For example, the first P-type material can be selected from compounds with the following structural formulas: 2,8-bis(9H-carbazol-9-yl)dibenzothiophene (DCzDBT), 2,7-bis(9H-carbazol-9-yl)-9,9-spirobifluorene (Spiro-2CBP), 2,2',7,7'-tetrakis(carbazol-9-yl)-9,9'-spirobifluorene (Spiro-CBP), etc. In this way, the HOMO energy level can be adjusted by changing the substitution position, etc.

[0171] In some exemplary embodiments, the fourth P-type material in the third host material H3 can be any one of polycarbazole compounds or aromatic amine compounds. Exemplarily, the fourth P-type material can be selected from: 3-(3-(9H-carbazol-9-yl)phenyl)-9-(3-(3-9(9H-carbazol-9-yl)phenyl)-9H-carbazol-9-yl)phenyl)-9H-carbazole (CPCB) compounds, 4,4',4"-tris(N-(1- The materials can be any one of the following compounds containing electron-donating groups: (naphthyl)-N-phenylamino)triphenylamine (4,4',4”-Tris(N-(1-naphthyl)-N-phenylamino)triphenylamine, abbreviated as 1-TNATA), and N,N'-diphenyl-N,N'-di-[4-(N,N-diphenylamino)phenyl]benzidine (N,N'-Diphenyl-N,N'-di-[4-(N,N-diphenyl-amino)phenyl]benzidine, abbreviated as NPNPB). Thus, by introducing electron-donating groups (such as polycarbazole groups or aromatic amine groups) into the fourth P-type material in the third host material H3, conjugation can be increased, thereby making the HOMO of the fourth P-type material shallower, which is beneficial for overcoming the energy level barrier of the host / guest material.

[0172] In some exemplary embodiments, the third N-type material in the third host material H3 is an N-type monomer material. For example, the third N-type material can be any of the triazine compounds or any of the indolocarbazole compounds, etc.

[0173] For example, taking the use of triazine compounds as the third N-type material, the third N-type material can be: 9,9'-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole)(9,9'-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)-1,3-phenylene)bis(9H-carbazole), abbreviated as DCzTRz).

[0174] For example, taking the third N-type material as an example of an indole-carbazole compound, the third N-type material can be selected from any of the compounds shown in formulas (3-1) and (3-2):

[0175]

[0176] In some exemplary embodiments, a third host material H3 can be formed by ternary co-evaporation of a third P-type material, a fourth P-type material, and a third N-type material.

[0177] In some exemplary embodiments, the concentration ratio between the sum of the concentrations of the third P-type material and the fourth P-type material and the concentration of the third N-type material in the third host material H3 can be approximately 6:4, thereby improving device efficiency and lifespan. For example, the concentration ratio of the third P-type material, the fourth P-type material, and the third N-type material can be approximately 3:3:4, or the concentration ratio of the third P-type material, the fourth P-type material, and the third N-type material can be approximately 4:2:4, etc. This disclosure does not specifically limit this aspect. The concentration ratio can refer to the rate ratio during evaporation, or the ratio of the evaporation thicknesses of the third P-type material, the fourth P-type material, and the third N-type material.

[0178] In some other exemplary embodiments, the third body material H3 may include: a third P-type material, a fourth P-type material, and a third N-type material, wherein the third P-type material, the fourth P-type material, and the third N-type material in the third body material H3 satisfy the following:

[0179] 0.5eV≤│HOMO(NH3)-HOMO(PH3-1)│≤0.7eV;

[0180] 0.3eV≤│LUMO(NH3)-HOMO(PH3-1)│≤0.5eV;

[0181] 0.7eV≤│HOMO(NH3)-HOMO(PH3-2)│≤0.9eV;

[0182] 0.5eV≤│LUMO(NH3)-HOMO(PH3-2)│≤0.7eV;

[0183] Wherein, HOMO(NH3) is the HOMO level of the third N-type material in the third host material H3, LUMO(NH1) is the LUMO level of the third N-type material in the third host material H3, HOMO(PH3-1) is the HOMO level of the third P-type material in the third host material H3, LUMO(PH3-1) is the LUMO level of the third P-type material in the third host material H3, HOMO(PH3-2) is the HOMO level of the fourth P-type material in the third host material H3, and LUMO(PH3-2) is the LUMO level of the fourth P-type material in the third host material H3.

[0184] Here, 0.5eV≤│HOMO(NH3)-HOMO(PH3-1)│ can mean: the difference between the HOMO energy level of the third N-type material and the HOMO energy level of the third P-type material is greater than or equal to 0.5eV, in which case the HOMO energy level of the third N-type material is greater than the HOMO energy level of the third P-type material; or, the difference between the HOMO energy level of the third N-type material and the HOMO energy level of the third P-type material is less than -0.5eV, in which case the HOMO energy level of the third N-type material is less than the HOMO energy level of the third P-type material. Similarly, the values ​​of |HOMO(NH3)-HOMO(PH3-1)|≤0.7eV, 0.3eV≤|LUMO(NH3)-HOMO(PH3-1)|≤0.5eV, 0.7eV≤|HOMO(NH3)-HOMO(PH3-2)|≤0.9eV, 0.5eV≤|LUMO(NH3)-HOMO(PH3-2)|≤0.7eV can be understood with reference to the above content, and will not be repeated here.

[0185] In some exemplary embodiments, the object material D can be a single-material luminescent layer with a single-material structure.

[0186] In some exemplary embodiments, the object material D satisfies:

[0187] 5eV≤│HOMO(D)│≤5.1eV, 2.3eV≤│LUMO(D)│≤2.4eV;

[0188] Wherein, HOMO(D) is the highest occupied molecular orbital HOMO energy level of guest material D, and LUMO(D) is the lowest unoccupied molecular orbital LUMO energy level of guest material D.

[0189] Thus, the HOMO energy level of guest material D can be any value from approximately -5.1 eV to -5 eV, for example, the HOMO energy level of guest material D can be approximately -5.1 eV, -5.05 eV, or -5 eV, etc. The LUMO energy level of guest material D can be any value from approximately -2.4 eV to -2.3 eV, for example, the LUMO energy level of guest material D can be approximately -2.4 eV, -2.35 eV, or -2.3 eV, etc. Here, the embodiments of this disclosure do not specifically limit this.

[0190] In some exemplary embodiments, the guest material may be a phosphorescent material, a fluorescent material, a delayed fluorescence material, etc. For example, the guest material D may be any one of the following: Tris(2-phenylpyridine)iridium(III), abbreviated as Ir(ppy)3; Tris[2-(p-tolyl)pyridine-C2,N]iridium(III), abbreviated as Ir(mppy)3; Acetylacetonatobis(2-phenylpyridine)iridium, abbreviated as Ir(ppy)2(acac); etc.

[0191] In some exemplary embodiments, the doping ratio of the guest material D in the light-emitting layer can be approximately 4% to 10%. For example, the doping ratio of the guest material D in the light-emitting layer can be approximately 4%, 5%, 6%, 7%, 7.5%, 8%, 9%, 9.5%, or 10%, etc. Here, the doping ratio can refer to the ratio of the weight of the guest material to the weight of the light-emitting layer, or it can refer to the rate ratio during evaporation, corresponding to the proportion of the evaporation thickness of the guest material to the total thickness of the light-emitting layer. For example, taking a light-emitting layer thickness of approximately 30 nm as an example, for a 30 nm thick light-emitting layer, a 10% doping ratio means that the evaporation thickness of the guest material is approximately 3 nm. Thus, by limiting the doping ratio of the guest material D within the above range, a long lifetime can be ensured while maintaining high efficiency.

[0192] In some exemplary embodiments, the object material D may be a green light-emitting material.

[0193] In some exemplary embodiments, a first P-type material and a first N-type material can be premixed to form a first host material H1, and a second P-type material and a second N-type material can be premixed to form a second host material H2. Then, the first host material H1, the second host material H2 and the guest material D can be deposited together by a ternary vapor deposition process to form a doped light-emitting layer.

[0194] In some other exemplary embodiments, a third host material H3 can be formed by co-depositing a third P-type material, a fourth P-type material, and a third N-type material through a ternary vapor deposition process. Then, the third host material H3 and the guest material D can be co-deposited through a binary vapor deposition process to form a doped light-emitting layer.

[0195] In some exemplary embodiments, the organic electroluminescent device may further include an auxiliary light-emitting layer disposed on the side of the light-emitting layer near the anode. The auxiliary light-emitting layer may be configured to perform at least one of the following functions: the auxiliary light-emitting layer is configured to lower the potential barrier and improve the matching degree with the host material, such as lowering the potential barrier between the hole transport layer and the host material, and efficiently transporting holes to the host material; the auxiliary light-emitting layer is configured to act as an electron blocking layer, blocking electrons transported from the cathode—electron transport layer—host material direction, preventing electrons from entering the hole transport layer and causing non-radiative decay transitions or entering the anode and causing leakage current, so that electrons and holes recombine within the light-emitting layer to form excitons, thereby improving the recombination efficiency of electrons and holes; the auxiliary light-emitting layer is configured to improve the luminous efficiency of the light-emitting layer, preventing excitons in the light-emitting layer from transferring energy to the hole transport layer via charge carriers, thus preventing excitons from undergoing non-radiative decay transitions in the hole transport layer, thereby improving the luminous efficiency of the light-emitting layer.

[0196] In some exemplary embodiments, the auxiliary light-emitting layer (also referred to as the Prime layer) may include a functional material (also referred to as the Prime material). For example, the material of the auxiliary light-emitting layer may be a green Prime material. In some exemplary embodiments, the material of the auxiliary light-emitting layer can be any one of the following: N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline (TAPC).

[0197] In some exemplary embodiments, the thickness of the prime layer can be approximately 40 nm to 70 nm. For example, the thickness of the prime layer can be approximately 40 nm, 50 nm, 55 nm, 60 nm, 65 nm, or 70 nm.

[0198] In some exemplary embodiments, the thickness of the emissive layer (EML) can be approximately 30 nm to 40 nm. For example, the thickness of the emissive layer (EML) can be approximately 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, or 40 nm. For example, the thickness of the green emissive layer (GEML) can be approximately 35 nm.

[0199] In some exemplary embodiments, for top-emitting devices, the cathode can be made of a transparent oxide material, such as indium tin oxide (ITO) or indium zinc oxide (IZO). The anode can be a composite structure of metal and transparent oxide, such as Ag / ITO, Ag / IZO, Al / ITO, Al / IZO, or ITO / Ag / ITO, which can ensure good reflectivity.

[0200] In some exemplary embodiments, the anode can be made of a material with a high work function. For example, for bottom-emitting OLEDs, the anode can be a transparent oxide material, such as indium tin oxide (ITO) or indium zinc oxide (IZO), and the thickness of the anode can be approximately 80 nm to 200 nm. As another example, for top-emitting OLEDs, the anode can be a composite structure of metal and transparent oxide, such as Ag / ITO, Ag / IZO, or ITO / Ag / ITO, etc., where the thickness of the metal layer in the anode can be approximately 80 nm to 100 nm, and the thickness of the transparent oxide in the anode can be approximately 5 nm to 20 nm, resulting in an average reflectance of approximately 85% to 95% in the visible light region.

[0201] In some exemplary embodiments, for bottom-emitting OLEDs, the cathode can be made of magnesium (Mg), silver (Ag), aluminum (Al), or an alloy of Mg:Ag. In some exemplary embodiments, the thickness of the cathode can be approximately 100 nm to 150 nm to give the cathode good reflectivity. For example, the thickness of the cathode can be approximately 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, or 150 nm, etc.

[0202] In some other exemplary embodiments, for top-emitting OLEDs, the cathode can be made of a metal material formed by a vapor deposition process. The metal material can be magnesium (Mg), silver (Ag), or aluminum (Al), or an alloy material, such as a Mg:Ag alloy, with a Mg:Ag ratio of approximately 3:7 to 1:9. The thickness of the cathode can be approximately 10 nm to 20 nm, so that the average transmittance of the cathode at a wavelength of 530 nm is approximately 50% to 60%.

[0203] In some exemplary embodiments, the hole injection layer (HIL) may be made of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN). In some exemplary embodiments, the thickness of the hole injection layer (HIL) may be approximately 10 nm.

[0204] In some exemplary embodiments, the hole transport layer (HTL) may be made of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB). In some exemplary embodiments, the thickness of the hole transport layer (HTL) may be any value between approximately 90 nm and 120 nm; for example, the thickness of the hole transport layer (HTL) may be approximately 90 nm, 100 nm, 110 nm, or 120 nm.

[0205] In some exemplary embodiments, the hole blocking layer (HBL) may be made of 4,7-diphenyl-1,10-phenanthroline (Bphen). In some exemplary embodiments, the thickness of the hole blocking layer (HBL) may be any value from approximately 5 nm to 15 nm, for example, the thickness of the hole blocking layer (HBL) may be approximately 5 nm, 8 nm, 10 nm, 12 nm, or 15 nm.

[0206] In some exemplary embodiments, the electron transport layer (ETL) can be prepared by blending thiophene, imidazole, or azazine derivatives with lithium quinoline, wherein the lithium quinoline content in the electron transport layer can be approximately 30% to 70%. For example, the electron transport layer (ETL) can be made of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi). In some exemplary embodiments, the thickness of the electron transport layer (ETL) can be any value between approximately 20 nm and 35 nm, for example, the thickness of the electron transport layer (ETL) can be approximately 20 nm, 25 nm, 30 nm, or 35 nm.

[0207] In some exemplary embodiments, the electron injection layer (EIL) may be formed using materials such as lithium fluoride (LiF), lithium 8-hydroxyquinoline (LiQ), ytterbium (Yb), or calcium (Ca) via a vapor deposition process. In some exemplary embodiments, the thickness of the electron injection layer may be approximately 0.5 nm to 15 nm. For example, the thickness of the electron injection layer (EIL) may be approximately 10 nm.

[0208] In some exemplary embodiments, for top-emitting OLEDs, the thickness of the film layer (first functional layer, light-emitting layer and second functional layer) between the anode and cathode can be designed to meet the optical path requirements of the optical micro-resonator in order to obtain optimal light emission intensity and color.

[0209] Figure 5 This is a schematic diagram of the structure of a light-emitting device according to an exemplary embodiment of the present disclosure. The exemplary devices in this disclosure include: device 1, device 2, and device 3, as shown below. Figure 5 As shown, the device structures of devices 1, 2, and 3 are: Anode / HIL / HTL / Prime / H1:H2:D / HBL / ETL / EIL / Cathode. Here, a green light-emitting device is used as an example for the experiment.

[0210] In devices 1 to 3, the materials and thicknesses of each film layer are as follows: The anode uses ITO / Ag / ITO with a thickness of 8 / 100 / 8 nm; the hole injection layer (HIL) uses 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN) with a thickness of approximately 10 nm; the hole transport layer (HTL) uses N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) with a thickness of approximately 100 nm; the auxiliary light-emitting layer (Prime) uses 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline (TAPC) with a thickness of approximately 40 nm; the light-emitting layer (EML) uses H1:H2: Material D, H1:H2:D = 47:47:6, means that the light-emitting layer (EML) is formed by ternary co-evaporation of the first host material H1, the second host material H2, and the guest material D in a volume ratio of 47:47:6. The guest material D is tri(2-phenylpyridine)iridium(III)(Ir(ppy)3) material. For example, the green light-emitting layer (GEML) has a thickness of about 35 nm; the hole blocking layer (HBL) is made of 4,7-diphenyl-1,10-phenanthroline (Bphen) material, and the hole blocking layer (HBL) has a thickness of about 5 nm; the electron transport layer (ETL) is made of TPBi material, and the electron transport layer (ETL) has a thickness of about 30 nm; the electron injection layer (EIL) is made of ytterbium (Yb) material, and the electron injection layer (EIL) has a thickness of 10 nm; the cathode (Cathode) is made of Mg:Ag alloy, and the cathode has a thickness of about 130 nm.

[0211] In device 1, the HOMO level of the first P-type material in the first host material H1 is approximately -5.5 eV, the LUMO level of the first P-type material in the first host material H1 is approximately -2.4 eV, the HOMO level of the first N-type material in the first host material H1 is approximately -6.1 eV, and the LUMO level of the first N-type material in the first host material H1 is approximately -2.8 eV. In device 1, the HOMO level of the second P-type material in the second host material H2 is approximately -5.3 eV, the LUMO level of the second P-type material in the second host material H2 is approximately -2.2 eV, the HOMO level of the second N-type material in the second host material H2 is approximately -5.9 eV, and the LUMO level of the second N-type material in the second host material H2 is approximately -2.6 eV. In device 1, the first P-type material in the first host material H1 is a 4,4'-bis(N-carbazole)-1,1'-biphenyl (CBP) compound, the first N-type material in the first host material H1 is a T2T material, the second P-type material in the second host material H2 is a 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) compound, and the second N-type material in the second host material H2 is a compound material as shown in formula (2-1). The first P-type material in the first host material H1 is premixed with the first host material H1 in a 1:1 ratio.

[0212] In device 2, the HOMO level of the first P-type material in the first host material H1 is approximately -5.6 eV, the LUMO level of the first P-type material in the first host material H1 is approximately -2.5 eV, the HOMO level of the first N-type material in the first host material H1 is approximately -6.2 eV, and the LUMO level of the first N-type material in the first host material H1 is approximately -2.9 eV. In device 2, the HOMO level of the second P-type material in the second host material H2 is approximately -5.3 eV, and the LUMO level is approximately -2.2 eV; the HOMO level of the second N-type material in the second host material H2 is approximately -5.9 eV, and the LUMO level is approximately -2.6 eV; the first P-type material in the first host material H1 in device 2 is an mCP compound material, the first N-type material in the first host material H1 in device 2 is a compound material as shown in formula (1-1), the second P-type material in the second host material H2 in device 2 is a 1,3,5-tris(9-carbazolyl)benzene (TCP) compound material, and the second N-type material in the second host material H2 in device 2 is a compound material as shown in formula (2-2). The first P-type material in the first host material H1 in device 2 is premixed with the first host material H1 in a 1:1 ratio.

[0213] In device 3, the HOMO level of the first P-type material in the first host material H1 is approximately -5.6 eV, the LUMO level of the first P-type material in the first host material H1 is approximately -2.5 eV, the HOMO level of the first N-type material in the first host material H1 is approximately -6.2 eV, and the LUMO level of the first N-type material in the first host material H1 is approximately -2.9 eV. In device 3, the HOMO level of the second P-type material in the second host material H2 is approximately -5.4 eV, and the LUMO level is approximately -2.3 eV; the HOMO level of the second N-type material in the second host material H2 is approximately -6.0 eV, and the LUMO level of the second N-type material in the second host material H2 is approximately -2.7 eV; the first P-type material in the first host material H1 in device 3 is a 2,2'-bis(4-carbazolylphenyl)biphenyl (BCBP) compound; the first N-type material in the first host material H1 in device 3 is a compound material as shown in formula (1-2); the second P-type material in the second host material H2 in device 3 is a 3,6-bis(9-phenyl-9H-carbazo-3-yl)-9-phenyl-9H-carbazolyl (Tris-PCZ) compound; and the second N-type material in the second host material H2 in device 3 is a compound material as shown in formula (2-1). In device 3, the first P-type material in the first main material H1 is premixed with the first main material H1 in a 1:1 ratio.

[0214] Figure 6 As shown in Figure 6, the structure of the comparative device is: Anode / HIL / HTL / Prime / GH:GD / HBL / ETL / EIL / Cathode. In the comparative device, GH:GD refers to the co-evaporation of the green host material GH and the green guest material GD in a volume ratio of 6:4 to form the emissive layer (EML). The green host material GH is made of bis(carbazole) material, and the green guest material GD is made of Ir(ppy)3 material. The thickness of the emissive layer (EML) is 30 nm. In addition, in the comparative device, the film materials and thicknesses of Anode, HIL, HTL, Prime, HBL, ETL, and Cathode are the same as those of devices 1 to 3.

[0215] The first-frame luminance ratio (FFR) of the exemplary devices 1 to 3 and the comparative device in this disclosure was measured at different low brightness levels, such as 0.1 nit, 0.2 nit, and 0.3 nit, and the results are shown in Table 1. Here, the first-frame luminance ratio (FFR) refers to the proportion of the brightness of the first frame image in the overall display brightness of the display device.

[0216] Table 1. First-frame brightness ratio of the device disclosed herein and the comparative device at different brightness levels.

[0217]

[0218] As shown in Table 1, at different low brightness levels (e.g., 0.1 nit, 0.2 nit, and 0.3 nit), compared to comparative devices using some technologies, devices 1, 2, and 3 using the technology of this disclosure all show a significant improvement in the brightness of the first frame.

[0219] Experiments revealed that, in the comparative device, the HOMO difference ΔHOMO between the green host material GH and the green guest material GD was 0.5 eV. Holes were very easily trapped in the green guest material GD. When the display screen switched from black to white, the holes were trapped in the green guest material GD, resulting in fewer holes available for light emission and reduced brightness, manifested as a smaller initial brightness in the first frame. Compared to the comparative device structure, in the light-emitting layer of the device in this disclosure, by ensuring that the HOMO and LUMO energy levels of the first host material H1, the second host material H2, and the guest material D satisfy the aforementioned energy level range, an energy level ladder can be formed between the first host material H1 and the second host material H2. This energy level ladder helps overcome the energy level barrier, allowing some holes to form excitons with electrons on the host materials (first host material H1 and second host material H2), and then transfer energy to the triplet state of the guest material D for light emission through Dexter energy transfer. Additionally, some holes are directly transferred to the guest material D, directly forming excitons with electrons on the guest material D for light emission. This reduces the trap effect of the guest material D, facilitates the release of holes for recombination light emission, and promotes more carrier light emission, thereby effectively improving the brightness of the first frame.

[0220] Figure 7 The graph shows the first-frame luminance ratio (FFR) of the device disclosed herein and the comparative device under different brightness levels. Based on Table 1, which shows the first-frame luminance ratio (FFR) of exemplary devices 1 to 3 in this disclosure and the comparative device at different low brightness levels, such as 0.1 nit, 0.2 nit, and 0.3 nit, the following results are obtained: Figure 7 The results are shown. Figure 7 As shown, the horizontal axis represents brightness (unit: nit), and the vertical axis represents the percentage of brightness in the first frame. Figure 7In the diagram, a horizontal line with a solid circle represents the first-frame brightness percentage of device 1 under different low brightness levels; a long dashed line with a solid square represents the first-frame brightness percentage of device 2 under different low brightness levels; a short dashed line with a solid hexagon represents the first-frame brightness percentage of device 3 under different low brightness levels; and a dotted line with a solid triangle represents the first-frame brightness percentage of the comparison device under different low brightness levels. According to... Figure 7 It can be seen that devices 1 to 3 using ternary co-evaporation H1:H2:D can increase the first-frame ratio by more than 50% under low brightness. Furthermore, devices 1 to 3 using ternary co-evaporation H1:H2:D can achieve a smaller H / D level barrier, reducing hole accumulation on the prime side at low current densities and mitigating the degradation of the prime layer caused by hole accumulation.

[0221] Figure 8 This diagram illustrates the exciton ratio (Peak) results of device 2 under different current densities. Table 1 shows the exciton ratio (Peak) of the exemplary device 2 in this disclosure at different current densities (e.g., 1 J_25℃, 6.22 J_25℃, 15 J_25℃, and 30 J_25℃). Figure 8 The results are shown. Figure 8 As shown, the horizontal axis represents the position of the emissive layer (EML), with the left side showing the EML near the prime layer and the right side showing the EML near the hole blocking layer (HBL). The vertical axis represents the exciton ratio (Peak), ranging from 0 to 0.35. Figure 8 As shown, with the decrease in device current density, the exciton recombination region of device 2 widens, and high-energy excitons move away from the Prime / EML interface, reducing the degradation of the Prime layer. This is beneficial for improving device lifetime at low current densities and ultimately improving the device acceleration factor. Figure 8 In the diagram, horizontal lines with solid circles represent experimental data on the exciton ratio measured at 1 J - 25 °C, where 1 J - 25 °C refers to the curve showing the exciton distribution of device 2 in the EML layer at 1 J (joules) at room temperature; long dashed lines with solid squares represent experimental data on the exciton ratio measured at 6.22 J - 25 °C, where 6.22 J - 25 °C refers to the curve showing the exciton distribution of device 2 in the EML layer at 6.22 J at room temperature; short dashed lines with solid hexagons represent experimental data on the exciton ratio measured at 15 J - 25 °C, where 15 J - 25 °C refers to the curve showing the exciton distribution of device 2 in the EML layer at 15 J at room temperature; and dashed lines with solid triangles represent experimental data on the exciton ratio measured at 30 J - 25 °C, where 30 J - 25 °C refers to the curve showing the exciton distribution of device 2 in the EML layer at 30 J at room temperature.

[0222] Figure 9 This is a schematic diagram of the structure of another light-emitting device in an exemplary embodiment of this disclosure. For example... Figure 9 As shown, the device structure of exemplary device 4 in this disclosure is: Anode / HIL / HTL / Prime / H3:D / HBL / ETL / EIL / Cathode. In device 4, the film material and thickness of Anode, HIL, HTL, Prime, HBL, ETL, and Cathode are the same as those of devices 1 to 3.

[0223] In device 4, H3:D refers to the co-evaporation of the third host material H3 and the guest material D at a volume ratio of 6:4 to form the luminescent layer. H3 is formed by ternary co-evaporation of P1 / P2 / N, with a concentration ratio of P1:P2:N of 3:3:4. In the experiment, the HOMO energy level of the third P-type material in the third host material H3 is approximately -5.4 eV, satisfying 5.5 eV ≤ |HOMO(PH3-1)| ≤ 5.6 eV. In the experiment, the LUMO energy level of the third P-type material in the third host material H3 is approximately -2.4 eV, satisfying 2.4 eV ≤ |LUMO(PH3-1)| ≤ 2.5 eV. In the experiment, the HOMO energy level of the fourth P-type material in the third host material H3 is approximately -2.4 eV, satisfying 2.4 eV ≤ |LUMO(PH3-1)| ≤ 2.5 eV. The MO energy level is approximately -5.3 eV, satisfying 5.3 eV ≤ |HOMO(PH3-2)| ≤ 5.4 eV. The LUMO energy level of the fourth p-type material in the third host material H3 in the experiment is approximately -2.2 eV, satisfying 2.2 eV ≤ |LUMO(PH3-2)| ≤ 2.3 eV. The HOMO energy level of the third n-type material in the third host material H3 in the experiment is approximately -6.1 eV, satisfying 6.1 eV ≤ |HOMO(NH3)| ≤ 6.2 eV. The LUMO energy level of the third n-type material in the third host material H3 in the experiment is approximately -2.8 eV, satisfying 2.8 eV ≤ |LUMO(NH3)| ≤ 2.9 eV. The third P-type material in the third host material H3 is a 2,8-bis(9H-carbazole-9-yl)dibenzothiophene (DCzDBT) compound material, the fourth P-type material in the third host material H3 is a CPCB compound material, and the third N-type material in the third host material H3 is a 9,9'-(5-(4,6-diphenyl-1,3,5-triazine-2-yl)-1,3-phenylene)bis(9H-carbazole) (DCzTRz) material.

[0224] The first-frame luminance ratio (FFR) of the exemplary device 4 and the comparative device in this disclosure was measured at different low brightness levels (e.g., 0.1 nit, 0.2 nit, and 0.3 nit), and the results are shown in Table 2. Here, the first-frame luminance ratio (FFR) refers to the proportion of the brightness of the first frame image in the overall display brightness of the display device.

[0225] Table 2. First-frame brightness ratio of the device disclosed herein and the comparative device at different brightness levels.

[0226]

[0227] As shown in Table 2, at different low brightness levels (e.g., 0.1 nit, 0.2 nit, and 0.3 nit), compared to comparative devices using some technologies, device 4 using the technology of this disclosure has a significant improvement in the brightness of the first frame.

[0228] As can be seen from the above experimental results, the organic electroluminescent device in the exemplary embodiments of this disclosure can reduce the trap effect of the guest material by setting different host materials, which is conducive to releasing holes for recombination and light emission, and can significantly improve the first frame ratio of the light-emitting device, thereby effectively improving the problem of poor image ghosting.

[0229] This disclosure also provides a display substrate, which may include: a substrate and a plurality of light-emitting devices disposed on one side of the substrate, wherein at least one of the plurality of light-emitting devices may be an organic electroluminescent device as described in the exemplary embodiments above.

[0230] This disclosure also provides a display device, which may include: a display substrate described in one or more of the exemplary embodiments above.

[0231] Here, the display device can be a product with image (including still images or moving images, where moving images can be video) display capabilities. In some exemplary embodiments, the display device can be, but is not limited to, any product or component with display capabilities such as a mobile phone, tablet computer, television, monitor, laptop computer, in-vehicle display, or navigation device. This disclosure does not limit the type of display device. Other essential components of the display device are those that should be understood by those skilled in the art, and are not described in detail here, nor should they be construed as limiting this disclosure.

[0232] Furthermore, the display device in this disclosure embodiment may include, in addition to the structures exemplified in the above embodiments, other necessary components and structures, such as a circuit for providing electrical signals to the display substrate to drive the display substrate to emit light. This circuit may be called a control circuit, and may include at least one of a circuit board and an integrated circuit (IC) electrically connected to the display substrate; or a power supply system for supplying power to the display substrate. Those skilled in the art can design and supplement accordingly based on the type of display substrate and usage requirements, which will not be elaborated here.

[0233] The description of the above display device embodiments is similar to that of the above organic electroluminescent device embodiments, and has similar beneficial effects. For technical details not disclosed in the display device embodiments of this disclosure, those skilled in the art should refer to the descriptions in the organic electroluminescent device embodiments of this disclosure for understanding, and will not be repeated here.

[0234] While the embodiments disclosed herein are as described above, the above content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed herein, but the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. An organic electroluminescent device, characterized in that, include: An anode, a cathode, and a light-emitting layer disposed between the anode and the cathode, wherein the material of the light-emitting layer includes a host material and a guest material; The main material includes: a first main material or a second main material, wherein, The first type of main material includes: a first P-type material, a first N-type material, a second P-type material, and a second N-type material, wherein the first P-type material, the first N-type material, the second P-type material, and the second N-type material satisfy the following: 5.5eV≤│HOMO(PH1)│≤5.6eV, 2.4eV≤│LUMO(PH1)│≤2.5eV; 6.1eV≤│HOMO(NH1)│≤6.2eV, 2.8eV≤│LUMO(NH1)│≤2.9eV; 5.3eV≤│HOMO(PH2)│≤5.4eV, 2.2eV≤│LUMO(PH2)│≤2.3eV; 5.9eV≤│HOMO(NH2)│≤6eV, 2.6eV≤│LUMO(NH2)│≤2.7eV; Wherein, HOMO(PH1) is the highest occupied molecular orbital HOMO energy level of the first p-type material, LUMO(PH1) is the lowest unoccupied molecular orbital LUMO energy level of the first p-type material, HOMO(NH1) is the HOMO energy level of the first n-type material, LUMO(NH1) is the LUMO energy level of the first n-type material, HOMO(PH2) is the HOMO energy level of the second p-type material, LUMO(PH2) is the LUMO energy level of the second p-type material, HOMO(NH2) is the HOMO energy level of the second n-type material, and LUMO(NH2) is the LUMO energy level of the second n-type material. The second type of main material includes: a third type P material, a fourth type P material, and a third type N material, wherein the third type P material, the fourth type P material, and the third type N material satisfy the following: 5.5eV≤│HOMO(PH3-1)│≤5.6eV, 2.4eV≤│LUMO(PH3-1)│≤2.5eV; 5.3eV≤│HOMO(PH3-2)│≤5.4eV, 2.2eV≤│LUMO(PH3-2)│≤2.3eV; 6.1eV≤│HOMO(NH3)│≤6.2eV, 2.8eV≤│LUMO(NH3)│≤2.9eV; Wherein, HOMO(PH3-1) is the HOMO energy level of the third P-type material, LUMO(PH3-1) is the LUMO energy level of the third P-type material, HOMO(PH3-2) is the HOMO energy level of the fourth P-type material, LUMO(PH3-2) is the LUMO energy level of the fourth P-type material, HOMO(NH3) is the HOMO energy level of the third N-type material, and LUMO(NH1) is the LUMO energy level of the third N-type material.

2. The organic electroluminescent device according to claim 1, characterized in that, The first type of main material includes: a first main material formed by mixing a first P-type material and a first N-type material, and a second main material formed by mixing a second P-type material and a second N-type material, wherein the weight ratio of the first main material and the second main material is 1:

1.

3. The organic electroluminescent device according to claim 2, characterized in that, The light-emitting layer is formed by co-evaporation of the first host material, the second host material, and the guest material, with the concentration ratio of the first host material, the second host material, and the guest material being 48:48:4 to 45:45:

10.

4. The organic electroluminescent device according to claim 2, characterized in that, The first type of main material is selected from any one of the following: The first P-type material is any one of carbazole compounds; The first N-type material is any one of the triazine compounds or any one of the indolocarbazole compounds; The second P-type material is any one of polycarbazole compounds or aromatic amine compounds; The second N-type material is any one of the compounds that includes sterically hindered groups.

5. The organic electroluminescent device according to claim 1, characterized in that, The second type of main material is formed by ternary co-evaporation of a third P-type material, a fourth P-type material, and a third N-type material, and the concentration ratio between the sum of the concentrations of the third P-type material and the fourth P-type material and the concentration of the third N-type material is 6:

4.

6. The organic electroluminescent device according to claim 5, characterized in that, The second type of main material is selected from any one of the following: The third P-type material is any one of carbazole compounds; The fourth P-type material is any one of polycarbazole compounds or aromatic amine compounds; The third type N material is any one of the triazine compounds or any one of the indolcarbazole compounds.

7. The organic electroluminescent device according to any one of claims 1 to 6, characterized in that, The object material satisfies: 5eV≤│HOMO(D)│≤5.1eV, 2.3eV≤│LUMO(D)│≤2.4eV; Wherein, HOMO(D) is the HOMO energy level of the guest material, and LUMO(D) is the LUMO energy level of the guest material.

8. The organic electroluminescent device according to claim 7, characterized in that, The doping ratio of the guest material in the light-emitting layer is 4% to 10%.

9. A display substrate, characterized in that, It includes: a substrate and a plurality of light-emitting devices disposed on one side of the substrate, wherein at least one of the plurality of light-emitting devices is an organic electroluminescent device as described in any one of claims 1 to 8.

10. The display substrate according to claim 9, characterized in that, The organic electroluminescent device is an organic electroluminescent device that emits green light.

11. A display device, characterized in that, Includes the display substrate as described in claim 9 or 10.

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