Organic electroluminescent device and use thereof

Abstract

The application provides an organic electroluminescent device and application thereof. The organic electroluminescent device comprises a first electrode and a second electrode, a first light-emitting layer and a second light-emitting layer arranged between the first electrode and the second electrode, and a buffer layer arranged between the first light-emitting layer and the second light-emitting layer. The first light-emitting layer comprises a first organic material and a first light-emitting material with a first intrinsic peak wavelength. The second light-emitting layer comprises a second light-emitting material with a second intrinsic peak wavelength. The buffer layer comprises the first organic material. The difference between the first and second intrinsic peak wavelengths is greater than or equal to 30 nm. Through the specific arrangement of the buffer layer, the light color emitted by the organic electroluminescent device at different voltages remains consistent, the light color stability of the device is significantly improved, the device structure is simple, the preparation cost is low, the working voltage is low, the light-emitting efficiency is high, and the performance requirements of various displays or illuminations can be met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic electroluminescent display, and particularly relates to an organic electroluminescent device and application thereof. BACKGROUND

[0002] An organic electroluminescent device (OLED) is composed of a cathode, an anode and an organic layer stack between the cathode and the anode. By applying a voltage across the cathode and anode of the device, electrical energy can be converted into light. OLEDs have a wide viewing angle, high contrast ratio, and fast response time. In 1987, Tang and Van Slyke of Kodak reported an organic light-emitting device, which used an arylamine hole transport layer and a tris-8-hydroxyquinoline-aluminum layer as an electron transport layer and a light-emitting layer ("Organic electroluminescent diodes", Applied Physics Letters, 1987, 51(12): 913-915). After a voltage was applied across the device, green light was emitted from the device. This study laid the foundation for the development of modern organic light-emitting diodes. OLEDs have the advantages of low cost, low power consumption, high brightness, wide viewing angle, and thin thickness. After decades of development, OLEDs have been widely used in display and lighting fields.

[0003] From the device structure, OLEDs can be divided into single-layer structure and stacked structure (also known as series structure). A single-layer OLED contains only one light-emitting unit between the cathode and the anode, while a stacked OLED is stacked by multiple light-emitting units. A light-emitting unit usually contains at least one light-emitting layer, one hole transport layer and one electron transport layer. The light-emitting unit can further contain a hole injection layer, an electron injection layer, a hole blocking layer and an electron blocking layer. Although a single-layer OLED has only one light-emitting unit, the light-emitting unit can contain multiple light-emitting layers; for example, the light-emitting unit can contain a yellow light-emitting layer and a blue light-emitting layer, but the single-layer OLED contains only one pair of hole transport layer and electron transport layer. A stacked OLED contains at least two light-emitting units, i.e. at least two pairs of hole transport layer and electron transport layer. Multiple light-emitting units are arranged in a vertical stacked physical form, thereby realizing the series connection feature on the circuit, and thus being called stacked OLED (from the physical form) or series OLED (from the circuit connection). That is, at the same brightness, the current density required by the stacked OLED is smaller than that of the conventional single-layer OLED, thereby achieving the effect of prolonging the service life. However, at a constant current density, the brightness of the stacked OLED is higher than that of the conventional single-layer OLED, and the voltage is also increased.

[0004] White organic electroluminescent device (WOLED) has wide application prospects in the fields of lighting, backlight, full-color display, micro display, etc. In the traditional WOLED, red, green and blue or yellow and blue multiple light-emitting layers are usually vertically stacked together to obtain white light by mixing three primary colors, which can be realized by single-layer white light or stacked white light. The stacked white light usually contains at least two light-emitting units, such as a yellow light-emitting unit and a blue light-emitting unit, which are connected to each other by a charge generation layer (CGL). The advantage of stacked white light is color stability, and each light-emitting unit can be independently optimized to optimize the performance of the device. However, the operating voltage of stacked white light is high, which is usually the sum of the voltages of two light-emitting units under the same current density, which increases the burden of the driving circuit, especially incompatible with the low-voltage CMOS process used in micro display. On the contrary, single-layer white light integrates red, green and blue or yellow and blue multiple light-emitting layers in one light-emitting unit, i.e. only one pair of electron and hole transport systems is used without charge generation layer. This device structure is simple, low in production cost, short in preparation time, and most importantly, low in operating voltage, which is compatible with CMOS circuit, so it is widely used in micro display field.

[0005] However, single-layer white light is not easy to adjust independently for each light-emitting layer, and if the same type of light-emitting material is used, for example, fluorescent light-emitting materials are used for red, green and blue, the device efficiency is very low, and if phosphorescent light-emitting materials are used, the device lifetime is limited by the phosphorescent blue light and is reduced; if red and green phosphorescent light-emitting materials are used in combination with fluorescent blue light-emitting materials, color drift phenomenon, simply referred to as color drift phenomenon, will occur due to the mismatch of energy levels, that is, the color of light emitted by the device changes significantly at different operating points (voltage or current density) or different brightness. This is because in organic semiconductor materials, the mobility of holes is much higher than that of electrons, and the trend of electron injection and hole injection is also very different at different operating voltages. The electron injection increases much more sharply than the hole with the increase of the operating voltage, so in OLED, the recombination region in the light-emitting layer moves from the side adjacent to the electron transport layer to the side adjacent to the hole transport layer with the increase of the current density ("Recombination zone study of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure", Kyoung Soo Yook, Journal of Industrial and Engineering Chemistry, 2010, Vol. 16, No. 2, pp. 181-184). For single-layer WOLED, when the driving voltage increases, the center of the recombination region may move from one color light-emitting layer to another color light-emitting layer, so that the proportion of light of different colors changes significantly, resulting in a change in the color of the emitted light; for example, when the proportion of blue light increases, the emitted light is cold in tone; when the proportion of red light increases, the emitted light is warm in tone. This situation makes the color coordinates of the light emitted by the WOLED change at different operating points (different voltages or current densities) or different brightness, even to the extent that the naked eye can see, which is very disadvantageous for conventional lighting or display.

[0006] In patent CN100407437C, a white light device containing symmetric light-emitting layers and intermediate light-emitting layers is disclosed, which reduces the change of the spectrum with voltage, but this structure requires at least three light-emitting layers, and at least two symmetric light-emitting layers emit the same color, and needs to be symmetrically arranged on the upper and lower sides of the third light-emitting layer, the preparation process is complex, and the color drift is still relatively large.

[0007] In patent applications CN111081891A and CN111081892A, it is also mentioned to use a buffer layer between two light-emitting layers, but the purpose of the two patents is to move the color within a certain range, for example, from warm light to cold light on the blackbody curve, or from red light to near-infrared. Therefore, the buffer layer used is an electron blocking layer, which is different from the host material in any one of the light-emitting layers, and most importantly, its purpose is completely different from the present application.

[0008] Although the prior art discloses some white light organic electroluminescent devices, the devices generally have the problems of obvious color drift, unstable light color, poor electrical performance, complex device structure, etc. Therefore, developing an organic electroluminescent device with more stable light-emitting color and higher performance is an urgent problem to be solved in the field. SUMMARY

[0009] In order to develop an organic electroluminescent device with more stable light-emitting color and higher performance, one of the purposes of the present application is to provide an organic electroluminescent device comprising a first electrode and a second electrode, a first light-emitting layer and a second light-emitting layer disposed between the first electrode and the second electrode, and a buffer layer disposed between the first light-emitting layer and the second light-emitting layer;

[0010] The first light-emitting layer comprises a first organic material and a first light-emitting material;

[0011] The second light-emitting layer comprises a second light-emitting material;

[0012] The buffer layer comprises the first organic material;

[0013] The first light-emitting material has a first intrinsic peak wavelength, and the second light-emitting material has a second intrinsic peak wavelength;

[0014] The difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥ 30 nm.

[0015] In the organic electroluminescent device provided by this invention, a buffer layer is provided between the first light-emitting layer and the second light-emitting layer. By using the buffer layer containing the first organic material in the first light-emitting layer, holes can be smoothly introduced into the second light-emitting layer at low voltage. At the same time, the buffer layer also acts as a barrier to electrons at high voltage. In this way, the number of excitons in the first and second light-emitting layers can be kept relatively constant under different voltages, effectively limiting the movement of the recombination region. This ensures that the color of the light emitted by the organic electroluminescent device remains consistent under different voltages, with stable spectrum and small color drift, significantly improving the stability of the emitted color under different brightness or operating conditions. Moreover, the device has a simple structure, low manufacturing cost, and low operating voltage, which can meet the performance requirements of various displays and lighting, and is especially suitable for the micro-display field.

[0016] A second objective of the present invention is to provide a display component comprising the organic electroluminescent device as described in one objective.

[0017] A third objective of this invention is to provide an application of the organic electroluminescent device as described in one objective in electronic devices, electronic component modules, display devices, or lighting devices.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The organic electroluminescent device provided by this invention, by using a buffer layer containing the first organic material in the first luminescent layer, ensures that holes can smoothly enter the second luminescent layer at low voltage, while blocking electrons at high voltage. Under different voltages, the number of excitons in the first and second luminescent layers remains basically the same, effectively limiting the movement of the recombination region. This ensures that the color of the light emitted by the organic electroluminescent device remains consistent under different voltages, with minimal color drift, significantly improving the stability of the emitted color under different brightness or operating conditions. Moreover, the device has a simple structure, low manufacturing cost, low operating voltage, and high luminous efficiency, meeting the performance requirements of various displays or lighting, and is particularly suitable for the micro-display field. Attached Figure Description

[0020] Figure 1 A cross-sectional structural schematic diagram of the organic electroluminescent device 100 provided for a specific embodiment of the present invention;

[0021] Figure 2 A cross-sectional structural schematic diagram of an organic electroluminescent device 200 provided for another specific embodiment of the present invention;

[0022] Figure 3 A cross-sectional structural schematic diagram of an organic electroluminescent device 300 provided for another specific embodiment of the present invention;

[0023] Figure 4 The normalized spectra of the organic electroluminescent device provided in Embodiment 1 of the present invention under different voltages;

[0024] Figure 5 The normalized spectra of the organic electroluminescent device provided in Comparative Example 1 of the present invention under different voltages;

[0025] Figure 6 The graph shows the variation of CIEx of the organic electroluminescent devices provided in Embodiment 1 and Comparative Example 1 under different brightness levels.

[0026] Figure 7 The organic electroluminescent device provided in Embodiment 1 of the present invention has a brightness of 1.6-6461 cd / m². 2 A diagram showing the movement trajectory of color coordinates on a color coordinate graph within a range of 1931.

[0027] Figure 8 The organic electroluminescent device provided in Comparative Example 1 of the present invention has a brightness of 2-6647 cd / m². 2 A diagram showing the movement trajectory of color coordinates within the range on the 1931 color coordinate diagram. Detailed Implementation

[0028] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0029] As used herein, "top" means furthest from the substrate, and "bottom" means closest to the substrate. When the first layer is described as being "disposed" on the second layer, the first layer is positioned further from the substrate. Unless it is specified that the first layer is "in contact" with the second layer, other layers may exist between the first and second layers. For example, even if various organic layers exist between the cathode and anode, the cathode may still be described as being "disposed" on the anode.

[0030] As used herein, the term "organic electroluminescent device (OLED device)" includes an anode layer, a cathode layer, and one or more organic layers disposed between the anode layer and the cathode layer. An "OLED device" can be bottom-emitting, i.e., emitting light from the substrate side, or top-emitting, i.e., emitting light from the encapsulation layer side, or a transparent device, i.e., emitting light from both the substrate and encapsulation sides.

[0031] As used herein, the term "encapsulation layer" can refer to a thin-film encapsulation with a thickness of less than 100 micrometers, which includes one or more thin films directly deposited onto the device, or it can refer to a cover glass adhered to a substrate.

[0032] The values of HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels referred to herein are measured by electrochemical cyclic voltammetry, the most common method for determining the energy levels of organic semiconducting materials. The specific test method is as follows: a platinum electrode is used as the working electrode, an Ag / AgNO3 electrode is used as the reference electrode, a platinum wire electrode is used as the auxiliary electrode, the scanning speed is 100 mV / s, the test temperature is 25°C, and the solvent is anhydrous dichloromethane (DCM). In this article, all "HOMO energy levels" and "LUMO energy levels" are represented by negative values, and the smaller the value (i.e., the larger the absolute value), the deeper the energy level. The solvent window of this method is -3 V, corresponding to an energy level of -1.8 eV. Generally, if a material does not have a measured LUMO energy level using this method, it means that the actual LUMO energy level of the material is greater than -1.8 eV. In this article, for the compound X-128 used in the present application, the LUMO energy level is not measured due to the solvent window, but it can be determined that the LUMO energy level of the compound X-128 is greater than -1.8 eV, i.e., the LUMO energy level of the compound X-128 is shallower than -1.8 eV. In this article, when referring to the size of the energy level, it means the size of the value of the energy level test, for example, the LUMO energy level of the second organic material is less than that of the first organic material, which means that the value of the LUMO energy level of the second organic material is less than that of the first organic material, i.e., the LUMO energy level of the second organic material is deeper than that of the first organic material.

[0033] As used herein, the term "light extraction layer" can refer to a light diffusion film, or other microstructure with light extraction effect, or a thin film coating with light out-coupling effect.

[0034] The cross-sectional schematic diagram of the stacked or single-layer organic electroluminescent device provided in the present application is illustrative and non-limiting, and the diagram is not necessarily drawn to scale, and some layer structures in the diagram can be added or omitted as needed. The substrate thereof can be manufactured on various substrates, such as glass, plastic, silicon wafer, or metal. The properties and functions of each layer and the exemplary materials are described in more detail in U.S. Patent No. US7279704B2, columns 6-10, the entire contents of which are incorporated herein by reference.

[0035] As described herein, the degree of color shift is represented using ΔCIEx, defined as the difference between the maximum and minimum CIEx over a luminance range of 2-1000 cd / m 2 The ratio of the difference between the maximum and minimum CIEx to the maximum CIEx.

[0036] As used herein, "emission peak wavelength" refers to the peak wavelength of light emitted by an organic light emitting material in a bottom emitting device comprising at least an anode layer, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and a cathode layer. The "emission peak wavelength" of an organic light emitting material can vary somewhat depending on the particular material system, but should be within ±10 nm.

[0037] Devices prepared according to embodiments of the present application can be incorporated into a variety of consumer products having one or more electronic component modules (or units) of the devices. Some examples of these consumer products include flat panel displays, monitors, medical monitors, televisions, billboards, lights for indoor or outdoor illumination and / or signaling, heads-up displays, fully or partially transparent displays, flexible displays, smartphones, tablet computers, phablets, wearable devices, smartwatches, laptop computers, digital cameras, camcorders, viewfinders, micro-displays, 3-D displays, vehicle displays and tail lights.

[0038] Definitions of terms for substituents

[0039] Halogen or halide - as used herein, includes fluorine, chlorine, bromine and iodine.

[0040] Alkyl - as used herein, includes straight and branched chain alkyl groups. Alkyl groups can be alkyl groups having 1 to 20 carbon atoms, preferably alkyl groups having 1 to 12 carbon atoms, more preferably alkyl groups having 1 to 6 carbon atoms. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, neopentyl, 1-methylpentyl, 2-methylpentyl, 1-pentylhexyl, 1-butylpentyl, 1-heptyloctyl, 3-methylpentyl. Of the above, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl and n-hexyl are preferred. Additionally, alkyl groups can be optionally substituted.

[0041] Cycloalkyl - as used herein includes cyclic alkyl groups. Cycloalkyl groups can be cycloalkyl groups having 3 to 20 ring carbon atoms, preferably cycloalkyl groups having 4 to 10 carbon atoms. Examples of cycloalkyl groups include cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4,4-dimethylcyclohexyl, 1-adamantyl, 2-adamantyl, 1-norbornyl, 2-norbornyl, and the like. Of the above, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4,4-dimethylcyclohexyl are preferred. Additionally, cycloalkyl groups can be optionally substituted.

[0042] Heteroalkyl - As used herein, heteroalkyl includes one or more carbons in the alkyl chain being replaced by a heteroatom selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, a phosphorus atom, a silicon atom, a germanium atom, and a boron atom. Heteroalkyl can be a heteroalkyl having 1 to 20 carbon atoms, preferably a heteroalkyl having 1 to 10 carbon atoms, more preferably a heteroalkyl having 1 to 6 carbon atoms. Examples of heteroalkyl include methoxymethyl, ethoxymethyl, ethoxyethyl, methylthiomethyl, ethylthiomethyl, ethylthioethyl, methoxymethoxymethyl, ethoxymethoxymethyl, ethoxyethoxyethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, mercaptomethyl, mercaptoethyl, mercaptopropyl, aminomethyl, aminoethyl, aminopropyl, dimethylaminomethyl, trimethylgermylmethyl, trimethylgermylethyl, trimethylgermylisopropyl, dimethylethylgermylmethyl, dimethylisopropylgermylmethyl, t-butyldimethylgermylmethyl, triethygermylmethyl, triethygermylethyl, triisopropylgermylmethyl, triisopropylgermylethyl, trimethylsilylmethyl, trimethylsilylethyl, trimethylsilylisopropyl, triisopropylsilylmethyl, triisopropylsilylethyl. In addition, heteroalkyl can be optionally substituted.

[0043] Alkenyl - As used herein, encompasses straight-chain, branched-chain, and cyclic alkenyl groups. Alkenyl can be an alkenyl group containing 2 to 20 carbon atoms, preferably an alkenyl group having 2 to 10 carbon atoms. Examples of alkenyl include ethenyl, propenyl, 1 -butenyl, 2-butenyl, 3-butenyl, 1,3-butanedienyl, 1 -methylvinyl, styryl, 2,2-diphenylvinyl, 1,2-diphenylvinyl, 1 -methylallyl, 1,1 -dimethylallyl, 2-methylallyl, 1 -phenylallyl, 2-phenylallyl, 3-phenylallyl, 3,3-diphenylallyl, 1,2-dimethylallyl, 1 -phenyl- 1 -butenyl, 3-phenyl- 1 -butenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, cycloheptenyl, cycloheptatrienyl, cyclooctenyl, cyclooctatetraenyl, and norbornenyl. In addition, alkenyl can be optionally substituted.

[0044] Alkynyl - As used herein, encompasses straight-chain alkynyl groups. Alkynyl can be an alkynyl group containing 2 to 20 carbon atoms, preferably an alkynyl group having 2 to 10 carbon atoms. Examples of alkynyl include ethynyl, propynyl, propargyl, 1 -butynyl, 2-butynyl, 3-butynyl, 1 -pentynyl, 2-pentynyl, 3,3-dimethyl- 1 -butynyl, 3-ethyl-3-methyl- 1 -pentynyl, 3,3-diisopropyl 1 -pentynyl, phenylethynyl, phenylpropynyl, and the like. Of the above, ethynyl, propynyl, propargyl, 1 -butynyl, 2-butynyl, 3-butynyl, 1 -pentynyl, phenylethynyl are preferred. In addition, alkynyl can be optionally substituted.

[0045] Aryl or aromatic group – as used herein, both non-fused and fused systems are considered. The aryl group can be an aryl group having 6 to 30 carbon atoms, preferably an aryl group having 6 to 20 carbon atoms, and more preferably an aryl group having 6 to 12 carbon atoms. Examples of aryl groups include phenyl, biphenyl, terphenyl, triphenylene, tetraphenylene, naphthalene, anthracene, fenene, fluorene, pyrene, etc. Perylene and azulene, preferably phenyl, biphenyl, terphenyl, triphenylene, fluorene, and naphthalene. Examples of non-fused aryl groups include phenyl, biphenyl-2-yl, biphenyl-3-yl, biphenyl-4-yl, p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl, m-terphenyl-2-yl, o-tolyl, m-tolyl, p-tolyl, p-(2-phenylpropyl)phenyl, 4'-methyldiphenyl, 4”-tert-butyl-p-terphenyl-4-yl, o-cumyl, m-cumyl, p-cumyl, 2,3-xylyl, 3,4-xylyl, 2,5-xylyl, mesitylene, and m-tetraphenyl. Additionally, the aryl group may optionally be substituted.

[0046] Heterocyclic groups or heterocycles – as used herein, consider non-aromatic cyclic groups. Non-aromatic heterocyclic groups include saturated heterocyclic groups having 3-20 ring atoms and unsaturated non-aromatic heterocyclic groups having 3-20 ring atoms, wherein at least one ring atom is selected from the group consisting of nitrogen, oxygen, sulfur, selenium, silicon, phosphorus, germanium, and boron atoms. Preferred non-aromatic heterocyclic groups are those having 3 to 7 ring atoms, including at least one heteroatom such as nitrogen, oxygen, silicon, or sulfur. Examples of non-aromatic heterocyclic groups include ethylene oxide, oxetane, tetrahydrofuranyl, tetrahydropyranyl, dioxopentacyclic, dioxahexacyclic, acridineyl, dihydropyrroleyl, tetrahydropyrroleyl, piperidinyl, oxazolidinyl, morpholinyl, piperazineyl, oxetane-heptanetrienyl, thioheptanetrienyl, azirane-heptanetrienyl, and tetrahydrothiorroleyl. In addition, the heterocyclic group can be optionally substituted.

[0047] Heteroaryl - As used herein, a non-fused and fused heteroaromatic group that can contain 1 to 5 heteroatoms, at least one of which is selected from the group consisting of nitrogen, oxygen, sulfur, selenium, silicon, phosphorus, germanium and boron. Heteroaryl also refers to heteroaryl. The heteroaryl group can be a heteroaryl group having 3 to 30 carbon atoms, preferably a heteroaryl group having 3 to 20 carbon atoms, more preferably a heteroaryl group having 3 to 12 carbon atoms. Suitable heteroaryls include dibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene, benzoseleophene, carbazole, indolocarbazole, pyridinoindole, pyrrolopyridine, pyrazole, imidazole, triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazol, indolizine, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline, naphthridine, phtalazine, pteridine, xanthene, acridine, phenoxazine, phenothiazine, benzofuro[3,2-d]pyridine, furo[3,2-d]dipyridine, benzothieno[3,2-d]pyridine, thieno[3,2-d]dipyridine, benzoseleto[3,2-d]pyridine, seleto[3,2-d]dipyridine, preferably dibenzothiophene, dibenzofuran, dibenzoselenophene, carbazole, indolocarbazole, imidazole, pyridine, triazine, benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazole and nitrogen analogs thereof. Additionally, the heteroaryl group can be optionally substituted.

[0048] Alkoxy - As used herein, represented by -O-alkyl, -O-cycloalkyl, -O-heteroalkyl or -O-heterocyclyl. Examples and preferred examples of alkyl, cycloalkyl, heteroalkyl and heterocyclyl are the same as described above. The alkoxy group can be an alkoxy group having 1 to 20 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentoxy, hexyloxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, tetrahydrofuranyloxy, tetrahydropyranyloxy, methoxypropyloxy, ethoxyethyloxy, methoxymethyloxy and ethoxymethyloxy. Additionally, the alkoxy group can be optionally substituted.

[0049] Aryloxy - As used herein, represented by -O-aryl or -O-heteroaryl. Examples and preferred examples of aryl and heteroaryl are the same as described above. The aryloxy group can be an aryloxy group having 6 to 30 carbon atoms, preferably an aryloxy group having 6 to 20 carbon atoms. Examples of aryloxy groups include phenoxy and biphenyloxy. Additionally, the aryloxy group can be optionally substituted.

[0050] Arylalkyl - as used herein, encompasses an aryl group substituted with an alkyl group. The arylalkyl group can be an arylalkyl group having 7 to 30 carbon atoms, preferably an arylalkyl group having 7 to 20 carbon atoms, more preferably an arylalkyl group having 7 to 13 carbon atoms. Examples of arylalkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylisopropyl, 2-phenylisopropyl, phenyl-t-butyl, α-naphthylmethyl, 1-α-naphthylethyl, 2-α-naphthylethyl, 1-α-naphthylisopropyl, 2-α-naphthylisopropyl, β-naphthylmethyl, 1-β-naphthylethyl, 2-β-naphthylethyl, 1-β-naphthylisopropyl, 2-β-naphthylisopropyl, p-methylbenzyl, m-methylbenzyl, o-methylbenzyl, p-chlorobenzyl, m-chlorobenzyl, o-chlorobenzyl, p-bromobenzyl, m-bromobenzyl, o-bromobenzyl, p-iodobenzyl, m-iodobenzyl, o-iodobenzyl, p-hydroxybenzyl, m-hydroxybenzyl, o-hydroxybenzyl, p-aminobenzyl, m-aminobenzyl, o-aminobenzyl, p-nitrobenzyl, m-nitrobenzyl, o-nitrobenzyl, p-cyanobenzyl, m-cyanobenzyl, o-cyanobenzyl, 1-hydroxy-2-phenylisopropyl and 1-chloro-2-phenylisopropyl. Of the foregoing, benzyl, p-cyanobenzyl, m-cyanobenzyl, o-cyanobenzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylisopropyl and 2-phenylisopropyl are preferred. Additionally, the arylalkyl group can be optionally substituted.

[0051] Silyl - as used herein, encompasses a silicon group substituted with an alkyl group. The silyl group can be a silyl group having 3 to 20 carbon atoms, preferably a silyl group having 3 to 10 carbon atoms. Examples of silyl groups include trimethylsilyl, triethylsilyl, methyldiethylsilyl, ethyldimethylsilyl, tripropylsilyl, tributylsilyl, triisopropylsilyl, methyldiisopropylsilyl, dimethylisopropylsilyl, tri-t-butylsilyl, triisobutylsilyl, dimethyl-t-butylsilyl, methyldi-t-butylsilyl. Additionally, the silyl group can be optionally substituted.

[0052] Silyl - as used herein, encompasses a silicon group substituted with an alkyl group. The silyl group can be a silyl group having 3 to 20 carbon atoms, preferably a silyl group having 3 to 10 carbon atoms. Examples of silyl groups include trimethylsilyl, triethylsilyl, methyldiethylsilyl, ethyldimethylsilyl, tripropylsilyl, tributylsilyl, triisopropylsilyl, methyldiisopropylsilyl, dimethylisopropylsilyl, tri-t-butylsilyl, triisobutylsilyl, dimethyl-t-butylsilyl, methyldi-t-butylsilyl. Additionally, the silyl group can be optionally substituted.

[0053] Alkylgermyl - As used herein, encompasses an alkyl-substituted germyl group. The alkylgermyl group can be an alkylgermyl group having 3 to 20 carbon atoms, preferably an alkylgermyl group having 3 to 10 carbon atoms. Examples of alkylgermyl groups include trimethylgermyl, triethylgermyl, methyldiethylgermyl, ethyldimethylgermyl, tripropylgermyl, tributylgermyl, triisopropylgermyl, methyldiisopropylgermyl, dimethylisopropylgermyl, tri-t-butylgermyl, triisobutylgermyl, dimethyl-t-butylgermyl, methyldi-t-butylgermyl. Additionally, the alkylgermyl group can be optionally substituted.

[0054] Arylgermyl - As used herein, encompasses a at least one aryl or heteroaryl substituted germyl group. The arylgermyl group can be an arylgermyl group having 6 to 30 carbon atoms, preferably an arylgermyl group having 8 to 20 carbon atoms. Examples of arylgermyl groups include triphenylgermyl, phenyldiphenylgermyl, diphenylphenylgermyl, phenyldiethylgermyl, diphenylethylgermyl, phenyldimethylgermyl, diphenylmethylgermyl, phenyl diisopropylgermyl, diphenylisopropylgermyl, diphenylbutylgermyl, diphenylisobutylgermyl, diphenyl-t-butylgermyl. Additionally, the arylgermyl group can be optionally substituted.

[0055] The term "aza" in azadibenzofurans, azadibenzothiophenes and the like refers to one or at least two C-H groups in the corresponding aromatic fragment being replaced by a nitrogen atom. For example, azatriphenylenes include dibenzo[f,h]quinoxaline, dibenzo[f,h]quinoline and other analogs having two or more nitrogens in the ring system. Other nitrogen analogs of the above aza derivatives can be readily envisioned by one of ordinary skill in the art, and all such analogs are intended to be encompassed by the term as described herein.

[0056] In the present disclosure, when any of the terms from the group consisting of substituted alkyl, substituted cycloalkyl, substituted heteroalkyl, substituted heterocyclyl, substituted aralkyl, substituted alkoxy, substituted aryloxy, substituted alkenyl, substituted alkynyl, substituted aryl, substituted heteroaryl, substituted silylalkyl, substituted arylsilyl, substituted silylgermane, substituted aminyl, substituted acyl, substituted carbonyl, substituted carboxylate, substituted ester, substituted sulfinyl, substituted sulfonyl, and substituted phosphine is used, unless otherwise defined, it means that any of the alkyl, cycloalkyl, heteroalkyl, heterocyclyl, aralkyl, alkoxy, aryloxy, alkenyl, alkynyl, aryl, heteroaryl, silylalkyl, arylsilyl, silylgermane, aminyl, acyl, carbonyl, carboxylate, ester, sulfinyl, sulfonyl, and phosphine groups can be substituted with one or at least two groups selected from deuterium, halogen, unsubstituted alkyl having 1-20 carbon atoms, unsubstituted cycloalkyl having 3-20 ring carbon atoms, unsubstituted heteroalkyl having 1-20 carbon atoms, unsubstituted heterocyclyl having 3-20 ring atoms, unsubstituted aralkyl having 7-30 carbon atoms, unsubstituted alkoxy having 1-20 carbon atoms, unsubstituted aryloxy having 6-30 carbon atoms, unsubstituted alkenyl having 2-20 carbon atoms, unsubstituted alkynyl having 2-20 carbon atoms, unsubstituted aryl having 6-30 carbon atoms, unsubstituted heteroaryl having 3-30 carbon atoms, unsubstituted silylalkyl having 3-20 carbon atoms, unsubstituted arylsilyl having 6-20 carbon atoms, unsubstituted silylgermane having 3-20 carbon atoms, unsubstituted aminyl having 0-20 carbon atoms, acyl, carbonyl, carboxylate, ester, cyano, isocyano, mercapto, sulfinyl, sulfonyl, phosphine, and combinations thereof.

[0057] It should be understood that when a molecular fragment is described as a substituent or otherwise attached to another moiety, it can be written by its name according to whether it is a fragment (e.g., phenyl, phenylene, naphthyl, dibenzofuryl) or according to whether it is an entire molecule (e.g., benzene, naphthalene, dibenzofuran). As used herein, these different ways of specifying substituents or attached fragments are considered to be equivalent.

[0058] In the compounds mentioned in the present disclosure, hydrogen atoms can be partially or completely replaced by deuterium. Other atoms such as carbon and nitrogen can also be replaced by their other stable isotopes. Replacement of other stable isotopes in the compounds can be preferred due to its enhanced efficiency and stability of the device.

[0059] In the compounds mentioned in the present disclosure, multiple substitution means including double substitution up to the maximum available substitution. When a substituent in the compounds mentioned in the present disclosure represents multiple substitution (including double substitution, triple substitution, quadruple substitution, etc.), it means that the substituent can exist at multiple available substitution positions on the structure to which it is connected, and the substituent that exists at multiple available substitution positions can be the same structure or different structures.

[0060] In the compounds mentioned in the present disclosure, unless explicitly defined, for example, adjacent substituents can be optionally connected to form a ring, adjacent substituents in the compounds cannot be connected to form a ring. In the compounds mentioned in the present disclosure, adjacent substituents can be optionally connected to form a ring, which includes both the case where adjacent substituents can be connected to form a ring and the case where adjacent substituents are not connected to form a ring. When adjacent substituents can be optionally connected to form a ring, the formed ring can be a single ring or a multiple ring (including a spiro ring, a bridged ring, a fused ring, etc.), and an alicyclic ring, a heteroalicyclic ring, an aromatic ring, or a heteroaromatic ring. In this expression, adjacent substituents can refer to substituents bonded to the same atom, substituents bonded to carbon atoms directly bonded to each other, or substituents bonded to further away carbon atoms. Preferably, adjacent substituents refer to substituents bonded to the same carbon atom and substituents bonded to carbon atoms directly bonded to each other.

[0061] The expression that adjacent substituents can be optionally connected to form a ring is also intended to mean that two substituents bonded to the same carbon atom are connected to each other by a chemical bond to form a ring, which can be exemplified by the following formula:

[0062]

[0063] The expression that adjacent substituents can be optionally connected to form a ring is also intended to mean that two substituents bonded to carbon atoms directly bonded to each other are connected to each other by a chemical bond to form a ring, which can be exemplified by the following formula:

[0064]

[0065] The expression that adjacent substituents can be optionally connected to form a ring is also intended to mean that two substituents bonded to further away carbon atoms are connected to each other by a chemical bond to form a ring, which can be exemplified by the following formula:

[0066]

[0067] In addition, the expression that adjacent substituents can be optionally connected to form a ring is also intended to mean that, in the case where one of the two adjacent substituents represents hydrogen, the second substituent is bonded at the position to which the hydrogen atom is bonded, thereby forming a ring. This is exemplified by the following formula:

[0068]

[0069] In one embodiment, the present application provides an organic electroluminescent device comprising a first electrode and a second electrode, and a first light-emitting layer and a second light-emitting layer disposed between the first electrode and the second electrode, and a buffer layer disposed between the first light-emitting layer and the second light-emitting layer;

[0070] The first light-emitting layer comprises a first organic material and a first light-emitting material;

[0071] The second light-emitting layer comprises a second light-emitting material;

[0072] The buffer layer comprises the first organic material;

[0073] The first light-emitting material has a first intrinsic peak wavelength, and the second light-emitting material has a second intrinsic peak wavelength;

[0074] The difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥ 30 nm, for example, the difference is 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 45 nm, 48 nm, 50 nm, 52 nm, 55 nm, 58 nm, 60 nm, 65 nm, 70 nm, 75 nm, or 80 nm, etc.

[0075] In this embodiment, the "first organic material" in the buffer layer refers to a compound having the same chemical structural formula as the first organic material contained in the aforementioned first light-emitting layer, or a deuterated variant of the first organic material contained in the aforementioned first light-emitting layer. The deuterated variant refers to a compound obtained by replacing part or all of the hydrogen in the compound with deuterium.

[0076] In one embodiment, the first organic material has hole-transporting properties, which helps to transport holes at low current density, while helping to block electrons at high current density.

[0077] In one embodiment, the difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥ 40 nm.

[0078] In one embodiment, the difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥ 50 nm.

[0079] In one embodiment, the difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≤ 100 nm.

[0080] In one embodiment, the difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≤ 80 nm.

[0081] In one embodiment, the first intrinsic peak wavelength is greater than or equal to 500 nm and less than or equal to 580 nm, for example, 510 nm, 520 nm, 530 nm, 540 nm, 550 nm, 560 nm, or 570 nm.

[0082] In one embodiment, the first luminescent material is a phosphorescent luminescent material.

[0083] In one embodiment, the first intrinsic peak wavelength is greater than or equal to 500 nm and less than or equal to 580 nm, for example, 510 nm, 520 nm, 530 nm, 540 nm, 550 nm, 560 nm, or 570 nm.

[0084] In one embodiment, the first intrinsic peak wavelength is greater than or equal to 500 nm and less than or equal to 560 nm.

[0085] In one embodiment, the second luminescent material is a fluorescent luminescent material.

[0086] In one embodiment, the second intrinsic peak wavelength is greater than or equal to 430 nm and less than or equal to 500 nm, for example, 440 nm, 450 nm, 460 nm, 470 nm, 480 nm, or 490 nm.

[0087] In one embodiment, the second intrinsic peak wavelength is greater than or equal to 450 nm and less than 500 nm.

[0088] In one embodiment, the first luminescent layer further comprises a third luminescent material, the third luminescent material having a third intrinsic peak wavelength.

[0089] In one embodiment, the difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is greater than or equal to 30 nm, for example, 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 45 nm, 48 nm, 50 nm, 52 nm, 55 nm, 58 nm, 60 nm, 65 nm, 70 nm, 75 nm, or 80 nm.

[0090] In one embodiment, the difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is greater than or equal to 50 nm.

[0091] In one embodiment, the difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is greater than or equal to 70 nm.

[0092] In one embodiment, the third intrinsic peak wavelength is greater than the second intrinsic peak wavelength by at least 50 nm, such as 52 nm, 55 nm, 58 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, or 120 nm, etc.

[0093] In one embodiment, the third intrinsic peak wavelength is greater than the second intrinsic peak wavelength by at least 70 nm.

[0094] In one embodiment, the third intrinsic peak wavelength is greater than the second intrinsic peak wavelength by at least 90 nm.

[0095] In one embodiment, the third intrinsic peak wavelength is greater than or equal to 580 nm and less than or equal to 680 nm, such as 590 nm, 600 nm, 610 nm, 620 nm, 630 nm, 640 nm, 650 nm, 660 nm, or 670 nm, etc.

[0096] In one embodiment, the third intrinsic peak wavelength is less than or equal to 150 nm from the first intrinsic peak wavelength.

[0097] In one embodiment, the third intrinsic peak wavelength is less than or equal to 130 nm from the first intrinsic peak wavelength.

[0098] In one embodiment, the third intrinsic peak wavelength is less than or equal to 100 nm from the first intrinsic peak wavelength.

[0099] In one embodiment, the third intrinsic peak wavelength is less than or equal to 230 nm from the second intrinsic peak wavelength.

[0100] In one embodiment, the third intrinsic peak wavelength is less than or equal to 200 nm from the second intrinsic peak wavelength.

[0101] In one embodiment, the third intrinsic peak wavelength is less than or equal to 170 nm from the second intrinsic peak wavelength.

[0102] In one embodiment, the second light-emitting layer further comprises a second organic material.

[0103] In one embodiment, the second organic material has electron-transporting properties.

[0104] In one embodiment, the second organic material has a LUMO energy level that is less than the LUMO energy level of the first organic material.

[0105] In one embodiment, the second light-emitting layer further comprises the first organic material.

[0106] In this embodiment, the “first organic material” in the second light-emitting layer refers to a compound having the same chemical structural formula as the first organic material contained in the aforementioned first light-emitting layer, or a deuterated variant of the first organic material contained in the aforementioned first light-emitting layer. The deuterated variant refers to a compound obtained by replacing part or all of the hydrogen in the compound with deuterium.

[0107] In one embodiment, the mass percentage (doping ratio) of the first organic material in the second light-emitting layer is 1% to 90%, which can be, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, or 80%, etc.

[0108] In one embodiment, the mass percentage (doping ratio) of the first organic material in the second light-emitting layer is 5% to 50%.

[0109] In one embodiment, the mass percentage (doping ratio) of the first organic material in the second light-emitting layer is 10% to 30%.

[0110] In one embodiment, the first organic material has a structure as shown in Formula I:

[0111]

[0112] wherein,

[0113] L X is selected from the group consisting of a single bond, substituted or unsubstituted alkylene having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkylene having 3 to 20 carbon atoms, substituted or unsubstituted arylene having 6 to 30 carbon atoms, substituted or unsubstituted heteroarylene having 3 to 30 carbon atoms, and a combination thereof;

[0114] Ar1and Ar2are each independently at each occurrence selected from the group consisting of substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, and a combination thereof;

[0115] X1-X 16 is selected from C, CR X , or N;

[0116] R Xeach occurrence is the same or different selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1-20 carbon atoms, substituted or unsubstituted heterocyclyl having 3-20 ring atoms, substituted or unsubstituted aralkyl having 7-30 carbon atoms, substituted or unsubstituted alkoxy having 1-20 carbon atoms, substituted or unsubstituted aryloxy having 6-30 carbon atoms, substituted or unsubstituted alkenyl having 2-20 carbon atoms, substituted or unsubstituted aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, substituted or unsubstituted alkylsilicon having 3-20 carbon atoms, substituted or unsubstituted arylsilicon having 6-20 carbon atoms, substituted or unsubstituted alkyl germanium having 3-20 carbon atoms, substituted or unsubstituted aryl germanium having 6-20 carbon atoms, substituted or unsubstituted amino having 0-20 carbon atoms, acyl, carbonyl, carboxylic acid group, ester group, cyano, isocyano, mercapto, hydroxyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0117] adjacent substituents R X may optionally be linked to form a ring.

[0118] In this context, "adjacent substituents R X may optionally be linked to form a ring" is intended to mean that any adjacent substituents R X may be linked to form a ring. Obviously, none of these substituents can also be linked to form a ring.

[0119] In one specific embodiment, the first organic material has a structure as shown in Formula I-a:

[0120]

[0121] wherein,

[0122] L X each occurrence is the same or different selected from the group consisting of single bond, substituted or unsubstituted alkylene having 1-20 carbon atoms, substituted or unsubstituted cycloalkylene having 3-20 carbon atoms, substituted or unsubstituted arylene having 6-30 carbon atoms, substituted or unsubstituted heteroarylene having 3-30 carbon atoms, and combinations thereof;

[0123] Ar1and Ar2are each occurrence the same or different selected from the group consisting of substituted or unsubstituted aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, and combinations thereof;

[0124] X1-X5, X7-X 10 and X 12 -X 16 is, at each occurrence, independently selected from the group consisting of CR X or N;

[0125] R X is, at each occurrence, independently selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having from 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having from 1 to 20 carbon atoms, substituted or unsubstituted heterocyclyl having from 3 to 20 ring atoms, substituted or unsubstituted aralkyl having from 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having from 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having from 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having from 2 to 20 carbon atoms, substituted or unsubstituted aryl having from 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having from 3 to 30 carbon atoms, substituted or unsubstituted alkylsilicon having from 3 to 20 carbon atoms, substituted or unsubstituted arylsilicon having from 6 to 20 carbon atoms, substituted or unsubstituted alkylgermanium having from 3 to 20 carbon atoms, substituted or unsubstituted arylgermanium having from 6 to 20 carbon atoms, substituted or unsubstituted amino having from 0 to 20 carbon atoms, acyl, carbonyl, carboxylic acid group, ester group, cyano, isocyano, mercapto, hydroxyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0126] adjacent substituents R X may optionally be linked into a ring.

[0127] In one particular embodiment, the L X is, at each occurrence, independently selected from the group consisting of a single bond, substituted or unsubstituted arylene having from 6 to 20 carbon atoms, substituted or unsubstituted heteroarylene having from 3 to 20 carbon atoms, and combinations thereof.

[0128] In one particular embodiment, the L X is selected from the group consisting of a single bond, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and combinations thereof.

[0129] In one particular embodiment, the L X is selected from the group consisting of a single bond.

[0130] In one particular embodiment, the Ar1and Ar2are, at each occurrence, independently selected from the group consisting of substituted or unsubstituted aryl having from 6 to 20 carbon atoms, substituted or unsubstituted heteroaryl having from 3 to 20 carbon atoms, and combinations thereof.

[0131] In a specific embodiment, Ar1and Ar2are the same or different at each occurrence selected from the group consisting of phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylenyl, dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, pyridyl, pyrimidyl, quinolyl, and combinations thereof.

[0132] In a specific embodiment, R X is selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having from 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to 20 ring carbon atoms, substituted or unsubstituted aryl having from 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having from 3 to 30 carbon atoms, substituted or unsubstituted alkylsilyl having from 3 to 20 carbon atoms, cyano, isocyano, hydroxyl, thiol, and combinations thereof.

[0133] In a specific embodiment, R X is selected from the group consisting of hydrogen, deuterium, fluorine, substituted or unsubstituted aryl having from 6 to 20 carbon atoms, substituted or unsubstituted heteroaryl having from 3 to 20 carbon atoms, and combinations thereof.

[0134] In a specific embodiment, R X is selected from the group consisting of hydrogen, deuterium, fluorine, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted triphenylenyl, substituted or unsubstituted fluorenyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophenyl, and combinations thereof.

[0135] In a specific embodiment, the first organic material is selected from the group consisting of Compound X-1 to Compound X-133, wherein the specific structures of Compound X-1 to Compound X-133 are shown below:

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148] In one embodiment, the first light-emitting material has a general structure of M(L a ) m (L b ) n (L c ) q ;

[0149] wherein M is selected from a metal having an atomic mass greater than 40;

[0150] L a , L b , L c are respectively a first ligand, a second ligand, a third ligand coordinated to the M, which are the same or different in structure;

[0151] m is selected from 1, 2 or 3; n, q are each independently selected from 0, 1 or 2; the sum of m, n, q is equal to the oxidation state of the metal M; when m≥2, 2 or 3 L a are the same or different; when n=2, 2 L b are the same or different; when q=2, 2 L c are the same or different;

[0152] L a has a structure as shown in Formula II:

[0153]

[0154] wherein the dotted line represents the coordination site of the ligand to the metal M;

[0155] Cy is the same or different at each occurrence and is selected from the group consisting of a substituted or unsubstituted aryl having 6-24 ring atoms, a substituted or unsubstituted heteroaryl having 5-24 ring atoms, and combinations thereof; the Cy is connected to the metal M through a metal-carbon bond or a metal-nitrogen bond;

[0156] Z is the same or different at each occurrence and is selected from the group consisting of O, S, Se, NR1, CR1R1and SiR1R1; when two R1are present simultaneously, the two R1are the same or different;

[0157] Z1-Z8are the same or different at each occurrence and are selected from the group consisting of C, CR Z or N; at least one of Z1-Z4is C and is attached to the Cy; Z1, Z2, Z3, or Z4is attached to the metal M by a metal-carbon bond or a metal-nitrogen bond;

[0158] R1and R Z are the same or different at each occurrence and are selected from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having from 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to 20 ring carbon atoms, substituted or unsubstituted heteroalkyl having from 1 to 20 carbon atoms, substituted or unsubstituted heterocyclyl having from 3 to 20 ring atoms, substituted or unsubstituted aralkyl having from 7 to 30 carbon atoms, substituted or unsubstituted alkoxy having from 1 to 20 carbon atoms, substituted or unsubstituted aryloxy having from 6 to 30 carbon atoms, substituted or unsubstituted alkenyl having from 2 to 20 carbon atoms, substituted or unsubstituted aryl having from 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having from 3 to 30 carbon atoms, substituted or unsubstituted alkylsilicon having from 3 to 20 carbon atoms, substituted or unsubstituted arylsilicon having from 6 to 20 carbon atoms, substituted or unsubstituted alkyl germanium having from 3 to 20 carbon atoms, substituted or unsubstituted aryl germanium having from 6 to 20 carbon atoms, substituted or unsubstituted amino having from 0 to 20 carbon atoms, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, hydroxyl, thiol, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0159] adjacent substituents R1, R Z may optionally be linked to form a ring;

[0160] the L b and L c are the same or different and are monanionic bidentate ligands.

[0161] Herein, the L a , L b , L c may optionally be linked to form a multidentate ligand, for example, any two of L a , L b , L c are linked to form a tetradentate ligand or L a , L b , L c are linked to form a hexadentate ligand.

[0162] Herein, “adjacent substituents R1, R Z may optionally be linked to form a ring” is intended to mean between adjacent substituents R1in Formula II, between adjacent substituents R Zmay be connected to form a ring. Obviously, none of these substituents can also be connected to form a ring.

[0163] In one embodiment, M is selected from the group consisting of Cu, Ag, Au, Ru, Rh, Pd, Os, Ir, Pt.

[0164] In one embodiment, M is selected from the group consisting of Pt or Ir.

[0165] In one embodiment, Cy is selected from the group consisting of:

[0166]

[0167] wherein,

[0168] R represents, on each occurrence, the same or different, a single substitution, multiple substitution, or no substitution; when multiple R are present in any structure, the R are the same or different;

[0169] R is selected, on each occurrence, from the group consisting of hydrogen, deuterium, halogen, substituted or unsubstituted alkyl of 1-20 carbon atoms, substituted or unsubstituted cycloalkyl of 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl of 1-20 carbon atoms, substituted or unsubstituted heterocyclyl of 3-20 ring atoms, substituted or unsubstituted aralkyl of 7-30 carbon atoms, substituted or unsubstituted alkoxy of 1-20 carbon atoms, substituted or unsubstituted aryloxy of 6-30 carbon atoms, substituted or unsubstituted alkenyl of 2-20 carbon atoms, substituted or unsubstituted alkynyl of 2-20 carbon atoms, substituted or unsubstituted aryl of 6-30 carbon atoms, substituted or unsubstituted heteroaryl of 3-30 carbon atoms, substituted or unsubstituted alkylsilicon of 3-20 carbon atoms, substituted or unsubstituted arylsilicon of 6-20 carbon atoms, substituted or unsubstituted alkyl germanium of 3-20 carbon atoms, substituted or unsubstituted aryl germanium of 6-20 carbon atoms, substituted or unsubstituted amino of 0-20 carbon atoms, acyl, carbonyl, carboxyl, ester, cyano, isocyano, hydroxyl, thiol, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0170] Adjacent substituents R can optionally be connected to form a ring;

[0171] wherein, “#” represents the position connected to the metal M, represents the position connected to Z1, Z2, Z3, or Z4.

[0172] In the present text, "adjacent substituents R can optionally be linked to form a ring" is intended to mean that between any two adjacent substituents R in formula I a linkage can be formed to form a ring. Obviously, also none of these substituents can be linked to form a ring.

[0173] In one particular embodiment, the L b and L c are each, on each occurrence identically or differently, selected from the group consisting of:

[0174]

[0175] wherein the dotted line represents a coordination site of the ligand to the metal M;

[0176] R a , R b and R c are each, on each occurrence identically or differently, mono-, poly- or un- substituted;

[0177] X b is each, on each occurrence identically or differently, selected from the group consisting of: O, S, Se, NR N1 , CR C1 R C2 ;

[0178] R a , R b , R c , R N1 , R C1 and R C2 are each, on each occurrence identically or differently, selected from the group consisting of: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl having 1-20 carbon atoms, substituted or unsubstituted heterocyclyl having 3-20 ring atoms, substituted or unsubstituted aralkyl having 7-30 carbon atoms, substituted or unsubstituted alkoxy having 1-20 carbon atoms, substituted or unsubstituted aryloxy having 6-30 carbon atoms, substituted or unsubstituted alkenyl having 2-20 carbon atoms, substituted or unsubstituted aryl having 6-30 carbon atoms, substituted or unsubstituted heteroaryl having 3-30 carbon atoms, substituted or unsubstituted alkylsilicon having 3-20 carbon atoms, substituted or unsubstituted arylsilicon having 6-20 carbon atoms, substituted or unsubstituted alkyl germanium having 3-20 carbon atoms, substituted or unsubstituted aryl germanium having 6-20 carbon atoms, substituted or unsubstituted amino having 0-20 carbon atoms, acyl, carbonyl, carboxylic, ester, cyano, isocyano, hydroxyl, thiol, sulfinyl, sulfonyl, phosphino, and combinations thereof;

[0179] adjacent substituents R a , R b , R c , R N1 , R C1 , R C2 may optionally be linked to form a ring.

[0180] Herein, "adjacent substituents R a , R b , R c , R N1 , R C1 , R C2 may optionally be linked to form a ring" is intended to mean that when there are substituents R a , R b , R c , R N1 , R C1 , R C2 , wherein adjacent groups of substituents, e.g., between two substituents R a , between two substituents R b , between two substituents R c , between substituents R a and R b , between substituents R a and R c , between substituents R b and R c , between substituents R a and R N1 , between substituents R b and R N1 , between substituents R a and R C1 , between substituents R a and R C2 , between substituents R b and R C1 , between substituents R b and R C2 , and between R C1 and R C2 , any one or more of these groups of substituents can be linked to form a ring. It is clear that these substituents can also not be linked to form a ring.

[0181] In one embodiment, at least one of Z1-Z8 is selected from CR Z , and said R z is selected from cyano.

[0182] In one embodiment, at least one of Z1-Z8 is selected from CR Z , and said R zselected from the group consisting of CR Z , and said R z is selected from the group consisting of a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 30 carbon atoms, or a combination thereof.

[0183] In one embodiment, at least one of Z5-Z8is selected from the group consisting of CR Z , and said R z is selected from the group consisting of a cyano group.

[0184] In one embodiment, at least one of Z5-Z8is selected from the group consisting of CR Z , and said R z is selected from the group consisting of a cyano group. Z , and said R z is selected from the group consisting of a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 30 carbon atoms, or a combination thereof.

[0185] In one embodiment, at least one of Z7-Z8is selected from the group consisting of CR Z , and said R z is selected from the group consisting of a cyano group.

[0186] In one embodiment, Z7and Z8are selected from the group consisting of CR Z , and one of said R z is selected from the group consisting of a cyano group, and the other R z is selected from the group consisting of a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 30 carbon atoms, or a combination thereof.

[0187] In one embodiment, the first light emitting material is selected from the group consisting of the following compounds:

[0188]

[0189]

[0190]

[0191]

[0192] In one specific embodiment, the mass percentage of the first light-emitting material in the first light-emitting layer (i.e. the doping ratio) is ≤ 15%, such as 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0.5%, etc.

[0193] In one specific embodiment, the mass percentage of the first light-emitting material in the first light-emitting layer (i.e. the doping ratio) is ≤ 10%.

[0194] In one specific embodiment, the mass percentage of the first light-emitting material in the first light-emitting layer (i.e. the doping ratio) is ≤ 5%.

[0195] In one specific embodiment, the second light-emitting material is selected from the group consisting of the following compounds:

[0196]

[0197]

[0198]

[0199]

[0200] In one specific embodiment, the third light-emitting material is a phosphorescent light-emitting material.

[0201] In one specific embodiment, the mass percentage of the third light-emitting material in the first light-emitting layer is not higher than the mass percentage of the first light-emitting material in the first light-emitting layer.

[0202] In one specific embodiment, the thickness of the buffer layer is ≥ 0.5 nm and ≤ 5 nm, such as 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2 nm, 2.2 nm, 2.5 nm, or 2.8 nm, etc.

[0203] In one specific embodiment, the thickness of the buffer layer is ≥ 1 nm and ≤ 3 nm.

[0204] In one specific embodiment, the first light-emitting layer is a yellow light-emitting layer, and the second light-emitting layer is a blue light-emitting layer.

[0205] In one specific embodiment, the buffer layer is in contact with the first light-emitting layer and the second light-emitting layer.

[0206] Figure 1An organic electroluminescent device 100 is shown schematically and non- limitingly as a single-layer white organic electroluminescent device, comprising an anode 101 (first electrode), a hole injection layer 102, a hole transport layer 103, a yellow light-emitting layer 104 (first light-emitting layer), a buffer layer 105, a blue light-emitting layer 106 (second light-emitting layer), an electron transport layer 107, an electron injection layer 108, a cathode 109 (second electrode), and a cover layer 110. The anode 101 can be ITO, IZO, nickel, silver, aluminum, chromium, molybdenum, copper, gold, titanium, etc., or a multilayer structure of two or more metals or an alloy of two or more metals, and the anode 101 not only functions as an electrode but also serves to reflect light emitted by the light-emitting layer. In a top-emission white device, in order to facilitate microcavity adjustment, the reflectivity of the anode 101 should be no higher than 95% in the visible light range, preferably no higher than 80%, and more preferably no higher than 60%. The hole injection layer 102 can be a single layer of an organic semiconductor material such as HATCN, or a co-evaporated hole transport material and p-type conductive dopant material as a hole injection layer, and inorganic materials such as MoO3, WO3, V2O5, etc. can also be used. The cathode 109 is a transparent or semi-transparent cathode, preferably silver, aluminum, magnesium, ytterbium, gold, tin, etc., or a multilayer structure of two or more metals or an alloy of two or more metals, and can also be a transparent metal oxide such as ITO, ZnO, IGZO, IZO, etc. In a top-emission device, the transmittance of the cathode 109 should be higher than 20% in the visible light range, preferably higher than 30%, and more preferably higher than 40%. The cover layer 110 serves for light extraction and protection against ion bombardment in subsequent processes, and can be not only an organic material but also an inorganic material such as SnO, TeO2, ZnS, ZnSe, etc. The optical refractive index of the cover layer 110 should be greater than 1.8, preferably greater than 1.9, and more preferably greater than 2.0. In a bottom-emission device, the cover layer 110 can be omitted. The white organic electroluminescent device can further comprise an electron blocking layer 111 and / or a hole blocking layer 112, such as the device 200 shown in Figure 2 The white organic electroluminescent device can further comprise separate green light-emitting layer 1041 and red light-emitting layer 1042 instead of the yellow light-emitting layer 104, such as the device 300 shown in Figure 3 The white organic electroluminescent device can further comprise a second buffer layer 113 between the green light-emitting layer 1041 and the red light-emitting layer 1042. The white organic electroluminescent device can be prepared on a rigid substrate or on a flexible substrate.

[0207] The single-layer white organic electroluminescent device shown in Figures 1-3 may also be a separate unit, and a plurality of such separate units can be vertically stacked to form a stacked device by connecting the charge generation layers, which will not be described here.

[0208] The yellow light emitting layer 104 further comprises a first organic material and a first light emitting material. The yellow light emitting layer 104 can further comprise a third light emitting material. When the yellow light emitting layer 104 comprises only the first light emitting material, the first light emitting material emits yellow light. When the yellow light emitting layer 104 comprises the first light emitting material and the third light emitting material, the first light emitting material and the third light emitting material can emit green light and red light respectively to obtain the desired yellow light. In order to improve the efficiency of the device, the green light emitting material is preferably a phosphorescent light emitting material and the red light emitting material is preferably a phosphorescent light emitting material. The first organic material is a hole transporting material, which helps to transport holes at low current density. The doping ratio of the green light emitting material should be less than 15%, preferably less than 10%, and more preferably less than 5%. Similarly, the doping ratio of the red light emitting material should be less than the doping ratio of the GD material. The blue light emitting layer 106 comprises at least one second light emitting material. In order to achieve the best performance of the blue light emitting layer 106, different second organic materials can be selected as the host material of the blue light emitting layer 106 according to the different second light emitting materials. The second light emitting material is a fluorescent light emitting material. The blue light emitting layer 106 can further comprise the first organic material. The second organic material is generally an electron transporting material. Therefore, if the yellow light emitting layer 104 and the blue light emitting layer 106 are in direct contact, holes cannot be transported from the yellow light emitting layer 104 to the blue light emitting layer 106, which is particularly evident at low current density. As a result, holes are trapped in the yellow light emitting layer 104 and cannot enter the blue light emitting layer 106, so the color of the light emitted by the entire device is mainly yellow. When the carrier injection increases and the voltage increases, the carriers can enter different light emitting layers, and the color drift occurs.

[0209] In order to solve this problem, the present application adds a buffer layer 105 between the yellow light emitting layer 104 and the blue light emitting layer 106. The buffer layer 105 comprises the first organic material in the yellow light emitting layer 104. The material can transport holes, and the LUMO energy level of the material is preferably greater than the LUMO energy level of the second organic material, i.e. the LUMO energy level of the second organic material is deeper than the LUMO energy level of the first organic material. In this way, electrons can be confined in the blue light emitting layer 106 for light emission. In this case, even at low current density, holes can be transported to the blue light emitting layer 106, so that the color of the light emitted by the entire device is white or close to white. The thickness of the buffer layer 105 should be between 0.5 nm and 5 nm, and preferably between 1 nm and 3 nm.

[0210] The first organic material preferably has the structure shown in Formula I. The blue light emitting layer 106 can also comprise the first organic material to further help the transport of holes and to reduce the voltage. In this case, the proportion of the first organic material in the blue light emitting layer 106 is 1% to 90%, preferably 5% to 50%, and more preferably 10% to 30%.

[0211] In one embodiment, the present application provides a display assembly comprising an organic electroluminescent device as described above.

[0212] In one embodiment, the present application provides use of an organic electroluminescent device as described above in an electronic device, an electronic component module, a display device, or an illumination device.

[0213] Hereinafter, the present application will be described in more detail with reference to the following examples. It is to be understood that the following examples are for illustrative purposes only and are not meant to limit the scope of the present application. Based upon the examples described below, one skilled in the art could, by using one's skills in the art, make modifications thereto and thus obtain other embodiments of the present application.

[0214] Device Example 1

[0215] An organic electroluminescent device, specifically a single-layer top-emission white organic electroluminescent device 100, a schematic diagram of a cross-sectional structure is shown in Figure 1 , comprising an anode 101 (first electrode), a hole injection layer 102, a hole transport layer 103, a yellow light-emitting layer 104 (first light-emitting layer), a buffer layer 105, a blue light-emitting layer 106 (second light-emitting layer), an electron transport layer 107, an electron injection layer 108, a cathode 109 (second electrode), and a cover layer 110, which are sequentially arranged.

[0216] The preparation method of the organic electroluminescent device is as follows: first, a 0.7 mm thick glass substrate is used, and after washing the substrate with deionized water and detergent, the glass surface is treated with oxygen plasma and ultraviolet ozone; then, the substrate is dried in a glove box to remove moisture, and is loaded into a support and transferred into a vacuum chamber. A mask is used to evaporate a patterned thick metal nickel (Ni) as an anode 101, followed by evaporation of specified organic layers, in a vacuum degree of about 1 x 10 -6 Torr, at a rate of First, compounds HT and PD are simultaneously evaporated as a hole injection layer 102 (HIL, the mass ratio of HT to PD is 97:3, ), and compound HT is evaporated as a hole transport layer 103 (HTL, ), followed by simultaneous evaporation of compounds X-128, GD1, and RD as a yellow light-emitting layer 104 (YEML, the mass ratio of X-128, GD1, and RD is 193:4:3, ), and evaporation of compound X-128 as a buffer layer 105 (BFL, ), followed by co-evaporation of compound H2 and compound BD51 as blue light emitting layer 106 (BEML, mass ratio of H2 to BD51 is 196:4, ), followed by co-evaporation of compound ET and Liq as electron transport layer 107 (ETL, mass ratio of ET to Liq is 40:60, ), followed by evaporation of compound X-128 as yellow light emitting layer 104 (YEL, thickness of 30 nm), Yb as electron injection layer 108 (EIL); followed by co-evaporation of silver and magnesium as cathode 109 (Cathode, mass ratio of silver to magnesium is 70:20, ), and finally evaporation of CPL material (CPL material is selected to be a material with refractive index of about 1.68 at 620 nm, which is obtained by testing the CPL material with thickness of 30 nm evaporated on a silicon wafer by an ellipsometer of model ES01 from Beijing Rits Technologies Co., Ltd.) as capping layer 110 (Capping layer, ). Then the device is transferred back to the glove box and packaged with a glass cover sheet to obtain the organic electroluminescent device.

[0217] Device Example 2

[0218] An organic electroluminescent device, which is only different from Example 1 in that the material of the blue light emitting layer 106 is compound H2, compound X-128 and compound BD51, and the mass ratio of the three is 157:39:4.

[0219] Device Example 3

[0220] An organic electroluminescent device, which is only different from Example 1 in that X-128 in the yellow light emitting layer 104 and the buffer layer is replaced by X-127.

[0221] Device Comparative Example 1

[0222] An organic electroluminescent device, which is only different from Example 1 in that compound X-127 is evaporated as the buffer layer 105.

[0223] Device Comparative Example 2

[0224] An organic electroluminescent device, which is only different from Example 1 in that compound X-128 in the yellow light emitting layer 104 is replaced by compound X-4, and the thickness of the hole transport layer 103 is

[0225] The detailed device layer part structures and thicknesses of Example 1 to Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1. Among them, the layer using more than one material is obtained by doping different compounds in the weight ratio as recorded.

[0226] Table 1 Device structure of Examples 1-3, Comparative Examples 1 and 2

[0227]

[0228]

[0229] The material structure used in the device is shown as follows:

[0230]

[0231]

[0232] Device performance test and analysis

[0233] The color coordinates (CIEx, CIEy) and external quantum efficiency (EQE) of the devices in Examples 1-3 and Comparative Examples 1-2 were measured at a brightness of 1000 cd / m 2 The color coordinates (CIEx, CIEy) and external quantum efficiency (EQE) of the devices in Examples 1-3 and Comparative Examples 1-2 were measured at a brightness of 1000 cd / m

[0234] Table 2 Device performance of Examples 1-3, Comparative Examples 1-2

[0235]

[0236] In Example 1, the host material YH (first organic material) in the yellow light emitting layer (first light emitting layer) is X-128, which is the same first organic material having the structure of Formula I as the buffer layer; while in Comparative Example 1, although the buffer layer material also has hole transport performance, and both are the first organic material having the structure of Formula I in the present application, the materials used for the yellow light host and the buffer layer are not the same. The LUMO energy level of the YH material in Example 1 is greater than -1.8 eV (beyond the measurement range), while the LUMO energy level of the blue light host material H2 (second organic material) is -2.52 eV. It can be seen that the LUMO energy level of the blue light host material is deeper than that of the YH material, which can effectively prevent the transfer of electrons from the blue light host to the yellow light emitting layer through the buffer layer at low voltage. Compared with Comparative Example 1, although the EQE of Example 1 is slightly lower, the ΔCIEx is only 5.4%, while in Comparative Example 1 it is as high as 10%, indicating that the color shift of Comparative Example 1 is serious, while Example 1 has very good color stability. Figure 4 is the normalized spectrum diagram of the organic electroluminescent device provided by Example 1 at different voltages. Only the intensity of the red light changes with the change of voltage. Figure 5 is the normalized spectrum diagram of the organic electroluminescent device provided by Comparative Example 1 at different voltages. At low voltage, the red light intensity is large, and with the increase of voltage, the blue light intensity increases, which is larger than the red light, resulting in a large color shift range. Figure 6 is the normalized spectrum diagram of the organic electroluminescent device provided by Example 1 and Comparative Example 1 at different brightness (2-6000 cd / m2 The CIEx in Example 1 remained basically unchanged when the luminance increased, whereas the CIEx in Comparative Example 1 gradually decreased, which indicates that when the yellow light emitting layer host and the buffer layer are the same material, the light emitting color of the device can be kept stable at different voltages, i.e. the color drift is small at different luminances. Figure 7 is the luminance of the organic electroluminescent device provided in Example 1, which is 1.6-6461 cd / m 2 The color coordinate movement trajectory graph on the 1931 color coordinate graph in the range of 2-6647 cd / m Figure 7 As can be seen from the color coordinate movement trajectory graph on the 1931 color coordinate graph in the range of 2-6647 cd / m Figure 8 is the luminance of the organic electroluminescent device provided in Comparative Example 1, which is 2-6647 cd / m 2 The color coordinate movement trajectory graph on the 1931 color coordinate graph in the range of 2-6647 cd / m

[0237] Similarly, in Example 3, the only difference from Comparative Example 1 is that the same material X-127 as the buffer layer is used in the yellow light emitting layer, and it can be seen that the color drift of the example is also significantly smaller than that of Comparative Example 1.

[0238] In Comparative Example 2, the buffer layer material is the same as in Example 1, but the host material YH in the yellow light emitting layer is changed. Although the buffer layer material and the YH material are both the first organic material having the structure of Formula I in the present application, the material used for YH is not the same as the material used for the buffer layer. Compared with Example 1, not only does the EQE of Comparative Example 2 decrease from 5.31% to 4.00%, but also the ΔCIEx increases sharply to 20%, which indicates that Example 1 has better color stability than Comparative Example 2. Although there is a difference in the thickness of the hole transport layer used in Comparative Example 2 and Example 1, which only affects the microcavity effect, i.e. it will cause slight changes in color at a fixed operating point (voltage or current density), and does not affect the carrier transport, so the electrical properties and color drift at different operating points of the two device structures can be compared.

[0239] In Example 2, not only is the buffer layer and the yellow light emitting layer host the same material X-128, but the compound X-128 is also added to the blue light emitting layer. Adding the compound X-128 having hole transport performance to the blue light emitting layer is more conducive to the transport of holes to the blue light emitting layer, although the EQE decreases slightly, the ΔCIEx further decreases to only 4.1%, which indicates that the device provided in Example 2 has better color stability.

[0240] In summary, by using the same material as the host material in the yellow light emitting layer as the buffer layer, the holes can be ensured to enter the blue light emitting layer smoothly, and since the buffer layer also plays a role in blocking electrons, the number of excitons in the yellow light emitting layer and the blue light emitting layer can be maintained at a substantially equivalent level under different voltages, effectively limiting the movement of the recombination region, so that the color of the light emitted by the white light device remains consistent under different voltages. When the same first organic material with the structure of formula I is used as the buffer layer and the yellow light host material, it is proved to have good electrical performance and lower color drift.

[0241] The applicant declares that the organic electroluminescent device and its application of the present application are illustrated by the above-mentioned embodiments, but the present application is not limited to the above-mentioned process steps, i.e. it does not mean that the present application must rely on the above-mentioned process steps to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the raw materials selected by the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes a first electrode and a second electrode, a first light-emitting layer and a second light-emitting layer disposed between the first electrode and the second electrode, and a buffer layer disposed between the first light-emitting layer and the second light-emitting layer; The first light-emitting layer comprises a first organic material and a first light-emitting material; The second light-emitting layer comprises a second light-emitting material; The buffer layer is composed of the first organic material; The first luminescent material has a first intrinsic peak wavelength, and the second luminescent material has a second intrinsic peak wavelength; The difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥32nm.

2. The organic electroluminescent device according to claim 1, characterized in that, The difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥40nm.

3. The organic electroluminescent device according to claim 2, characterized in that, The difference between the first intrinsic peak wavelength and the second intrinsic peak wavelength is ≥50nm.

4. The organic electroluminescent device according to claim 1, characterized in that, The first luminescent material is a phosphorescent material; the first intrinsic peak wavelength is greater than or equal to 500 nm and less than or equal to 580 nm.

5. The organic electroluminescent device according to claim 4, characterized in that, The first intrinsic peak wavelength is greater than or equal to 500 nm and less than or equal to 560 nm.

6. The organic electroluminescent device according to claim 1, characterized in that, The second luminescent material is a fluorescent luminescent material; the second intrinsic peak wavelength is greater than or equal to 430 nm and less than or equal to 500 nm.

7. The organic electroluminescent device according to claim 6, characterized in that, The second intrinsic peak wavelength is greater than or equal to 450 nm and less than 500 nm.

8. The organic electroluminescent device according to claim 1, characterized in that, The first light-emitting layer further comprises a third light-emitting material, the third light-emitting material having a third intrinsic peak wavelength; The difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is ≥30nm.

9. The organic electroluminescent device according to claim 8, characterized in that, The difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is ≥50nm.

10. The organic electroluminescent device according to claim 9, characterized in that, The difference between the third intrinsic peak wavelength and the first intrinsic peak wavelength is ≥70nm; And / or, the difference between the third intrinsic peak wavelength and the second intrinsic peak wavelength is ≥50nm.

11. The organic electroluminescent device according to claim 10, characterized in that, The difference between the third intrinsic peak wavelength and the second intrinsic peak wavelength is ≥70nm.

12. The organic electroluminescent device according to claim 11, characterized in that, The difference between the third intrinsic peak wavelength and the second intrinsic peak wavelength is ≥90nm.

13. The organic electroluminescent device according to claim 8, characterized in that, The third intrinsic peak wavelength is greater than or equal to 580 nm and less than or equal to 680 nm.

14. The organic electroluminescent device according to any one of claims 1-13, characterized in that, The second light-emitting layer also contains a second organic material.

15. The organic electroluminescent device according to claim 14, characterized in that, The LUMO energy level of the second organic material is lower than that of the first organic material.

16. The organic electroluminescent device according to claim 14, characterized in that, The second light-emitting layer also contains the first organic material.

17. The organic electroluminescent device according to claim 1, characterized in that, The first organic material has a structure as shown in Formula I: Among them, L X Each time it appears, it is selected from the group consisting of the following, either the same or different: single bond, substituted or unsubstituted alkylene groups having 1-20 carbon atoms, substituted or unsubstituted cycloalkylene groups having 3-20 carbon atoms, substituted or unsubstituted arylene groups having 6-30 carbon atoms, substituted or unsubstituted heteroarylene groups having 3-30 carbon atoms, and combinations thereof. Ar1 and Ar2 are selected from the following groups, either identically or differently, each time they appear: substituted or unsubstituted aryl groups having 6-30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-30 carbon atoms, and combinations thereof. X1-X 16 Each time it appears, it is selected from C, CR, either identically or differently. X Or N; R X Each time it appears, it is selected from the group consisting of the same or different groups of the following: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl groups having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl groups having 1-20 carbon atoms, substituted or unsubstituted heterocyclic groups having 3-20 ring atoms, substituted or unsubstituted aralkyl groups having 7-30 carbon atoms, substituted or unsubstituted alkoxy groups having 1-20 carbon atoms, substituted or unsubstituted aroxy groups having 6-30 carbon atoms, and substituted or unsubstituted alkenes having 2-20 carbon atoms. alkyl, substituted or unsubstituted aryl groups having 6-30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-30 carbon atoms, substituted or unsubstituted alkylsilyl groups having 3-20 carbon atoms, substituted or unsubstituted arylsilyl groups having 6-20 carbon atoms, substituted or unsubstituted alkylgermanium groups having 3-20 carbon atoms, substituted or unsubstituted arylgermanium groups having 6-20 carbon atoms, substituted or unsubstituted amino, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, mercapto, hydroxyl, sulfinyl, sulfonyl, phosphinyl, and combinations thereof having 0-20 carbon atoms; Adjacent substituent R X They can be connected into a ring at will.

18. The organic electroluminescent device according to claim 17, characterized in that, The L X Each time it appears, it is selected from the following groups, either identically or differently: single bonds, substituted or unsubstituted aryl groups with 6-20 carbon atoms, substituted or unsubstituted heteroaryl groups with 3-20 carbon atoms, and combinations thereof.

19. The organic electroluminescent device according to claim 18, characterized in that, The L X Selected from single-bonded, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and combinations thereof.

20. The organic electroluminescent device according to claim 19, characterized in that, The L X It is a single key.

21. The organic electroluminescent device according to claim 17 or 18, characterized in that, Ar1 and Ar2, each time they appear, are selected from the group consisting of: substituted or unsubstituted aryl groups having 6-20 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-20 carbon atoms, and combinations thereof.

22. The organic electroluminescent device according to claim 21, characterized in that, Ar1 and Ar2, each time they appear, are selected from the group consisting of the same or different groups of: phenyl, biphenyl, terphenyl, naphthyl, phenanthrene, triphenylene, dimethylfluorenyl, dibenzofuranyl, dibenzothiophene, pyridyl, pyrimidinyl, quinolinyl, and combinations thereof.

23. The organic electroluminescent device according to claim 17, characterized in that, The R X Each time it appears, it is selected from the group consisting of the same or different groups of the following: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl groups having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3-20 cyclic carbon atoms, substituted or unsubstituted aryl groups having 6-30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-30 carbon atoms, substituted or unsubstituted alkylsilyl groups having 3-20 carbon atoms, cyano, isocyano, hydroxyl, mercapto, and combinations thereof.

24. The organic electroluminescent device according to claim 23, characterized in that, The R X Each time it appears, it is selected from the group consisting of the following, either the same or different: hydrogen, deuterium, fluorine, substituted or unsubstituted aryl groups having 6-20 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-20 carbon atoms, and combinations thereof.

25. The organic electroluminescent device according to claim 24, characterized in that, The R X Each time it appears, it is selected from the group consisting of the same or different groups of the following: hydrogen, deuterium, fluorine, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted triphenylene, substituted or unsubstituted fluorenyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophene, and combinations thereof.

26. The organic electroluminescent device according to claim 1 or 17, characterized in that, The first organic material is selected from the group consisting of the following compounds:

27. The organic electroluminescent device according to claim 1, characterized in that, The structural formula of the first luminescent material is M(L a ) m (L b ) n (L c ) q ; M is selected from metals with a relative atomic mass greater than 40; L a L b L c These are the first ligand, the second ligand, and the third ligand that coordinate with M, and their structures may be the same or different. m is selected from 1, 2, or 3; n and q are each independently selected from 0, 1, or 2; the sum of m, n, and q equals the oxidation state of the metal M; when m ≥ 2, there are 2 or 3 L a Same or different; when n=2, 2 L b Same or different; when q = 2, 2 L c Same or different; The L a It has a structure as shown in Equation II: The dashed lines represent the coordination binding sites between the ligand and the metal M. Cy is selected from the group consisting of the following, either identically or differently: substituted or unsubstituted aryl groups having 6-24 ring atoms, substituted or unsubstituted heteroaryl groups having 5-24 ring atoms, and combinations thereof; the Cy is connected to the metal M by a metal-carbon bond or a metal-nitrogen bond. Each time Z appears, it is selected from the following groups, either identically or differently: O, S, Se, NR1, CR1R1, and SiR1R1; when two R1s exist simultaneously, the two R1s are identical or different. Z1-Z8 are selected from C and CR each time they appear, either identically or differently. Z Or N; at least one of Z1-Z4 is C and connected to the Cy; Z1, Z2, Z3, or Z4 are connected to the metal M via metal-carbon bonds or metal-nitrogen bonds; R1 and R Z Each time it appears, it is selected from the group consisting of the same or different groups of the following: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl groups having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl groups having 1-20 carbon atoms, substituted or unsubstituted heterocyclic groups having 3-20 ring atoms, substituted or unsubstituted aralkyl groups having 7-30 carbon atoms, substituted or unsubstituted alkoxy groups having 1-20 carbon atoms, substituted or unsubstituted aroxy groups having 6-30 carbon atoms, and substituted or unsubstituted alkenes having 2-20 carbon atoms. alkyl, substituted or unsubstituted aryl groups having 6-30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-30 carbon atoms, substituted or unsubstituted alkylsilyl groups having 3-20 carbon atoms, substituted or unsubstituted arylsilyl groups having 6-20 carbon atoms, substituted or unsubstituted alkylgermanium groups having 3-20 carbon atoms, substituted or unsubstituted arylgermanium groups having 6-20 carbon atoms, substituted or unsubstituted amino, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, and combinations thereof having 0-20 carbon atoms; Adjacent substituents R1, R Z They can be arbitrarily connected to form a loop; The L b and L c They are either monoanionic bidentate ligands or different from each other.

28. The organic electroluminescent device according to claim 27, characterized in that, M is selected from Cu, Ag, Au, Ru, Rh, Pd, Os, Ir, or Pt.

29. The organic electroluminescent device according to claim 28, characterized in that, M is selected from Pt or Ir.

30. The organic electroluminescent device according to claim 27, characterized in that, The L b and L c Each time it appears, choose the group consisting of the following, either the same or different: The dashed lines represent the coordination binding sites between the ligand and the metal M. R a R b and R c Each occurrence, whether identical or different, indicates monosubstituted, polysubstituted, or unsubstituted. X b Each time it appears, choose from the following groups, either the same or different: O, S, Se, NR N1 CR C1 R C2 ; R a R b R c R N1 R C1 and R C2 Each time it appears, it is selected from the group consisting of the same or different groups of the following: hydrogen, deuterium, halogen, substituted or unsubstituted alkyl groups having 1-20 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3-20 ring carbon atoms, substituted or unsubstituted heteroalkyl groups having 1-20 carbon atoms, substituted or unsubstituted heterocyclic groups having 3-20 ring atoms, substituted or unsubstituted aralkyl groups having 7-30 carbon atoms, substituted or unsubstituted alkoxy groups having 1-20 carbon atoms, substituted or unsubstituted aroxy groups having 6-30 carbon atoms, and substituted or unsubstituted alkenes having 2-20 carbon atoms. alkyl, substituted or unsubstituted aryl groups having 6-30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3-30 carbon atoms, substituted or unsubstituted alkylsilyl groups having 3-20 carbon atoms, substituted or unsubstituted arylsilyl groups having 6-20 carbon atoms, substituted or unsubstituted alkylgermanium groups having 3-20 carbon atoms, substituted or unsubstituted arylgermanium groups having 6-20 carbon atoms, substituted or unsubstituted amino, acyl, carbonyl, carboxylic acid, ester, cyano, isocyano, hydroxyl, mercapto, sulfinyl, sulfonyl, phosphinyl, and combinations thereof having 0-20 carbon atoms; Adjacent substituent R a R b R c R N1 R C1 R C2 They can be arbitrarily connected to form a ring.

31. The organic electroluminescent device according to claim 1, characterized in that, The mass percentage of the first luminescent material in the first luminescent layer is ≤15%.

32. The organic electroluminescent device according to claim 31, characterized in that, The mass percentage of the first luminescent material in the first luminescent layer is ≤10%.

33. The organic electroluminescent device according to claim 32, characterized in that, The mass percentage of the first luminescent material in the first luminescent layer is ≤5%.

34. The organic electroluminescent device according to claim 8, characterized in that, The third luminescent material is a phosphorescent material.

35. The organic electroluminescent device according to claim 34, characterized in that, The mass percentage of the third luminescent material in the first luminescent layer is not higher than the mass percentage of the first luminescent material in the first luminescent layer.

36. The organic electroluminescent device according to claim 1, characterized in that, The thickness of the buffer layer is greater than or equal to 0.5 nm and less than or equal to 5 nm.

37. The organic electroluminescent device according to claim 36, characterized in that, The thickness of the buffer layer is greater than or equal to 1 nm and less than or equal to 3 nm.

38. The organic electroluminescent device according to claim 1, characterized in that, The buffer layer is in contact with the first light-emitting layer and the second light-emitting layer.

39. A display component, characterized in that, The display component includes an organic electroluminescent device as described in any one of claims 1-38.

40. The use of an organic electroluminescent device as described in any one of claims 1-38 in an electronic device, an electronic component module, a display device, or a lighting device.

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