CN112750957A

CN112750957A - Organic electroluminescent device

Info

Publication number: CN112750957A
Application number: CN202110004228.8A
Authority: CN
Inventors: 朱鸫达; 鲁秋; 韩春雪; 赵璐
Original assignee: Changchun Hyperions Technology Co Ltd
Current assignee: Changchun Hyperions Technology Co Ltd
Priority date: 2021-01-04
Filing date: 2021-01-04
Publication date: 2021-05-04
Anticipated expiration: 2041-01-04
Also published as: CN112750957B

Abstract

The invention provides an organic electroluminescent device, and relates to the technical field of organic electroluminescence. Compared with the traditional single-layer covering layer organic electroluminescent device, the covering layer in the organic electroluminescent device provided by the invention comprises the first covering layer and the second covering layer, and the total reflection loss can be better reduced by combining two materials with different refractive indexes, so that the luminous efficiency of the organic electroluminescent device is improved, and the stability of the film is good. The organic electroluminescent device has good application effect and industrialization prospect, and can be widely applied to the fields of panel display, lighting sources, organic solar cells, organic photoreceptors or organic thin film transistors and the like.

Description

Organic electroluminescent device

Technical Field

The invention relates to the technical field of organic electroluminescence, in particular to an organic electroluminescent device.

Background

An organic light-emitting diode (OLED) is an all-solid-state light-emitting device, has the advantages of lightness, thinness, high efficiency, low power consumption, flexibility, simple manufacturing process and the like, and is used in the field of mobile phones and televisions first. Meanwhile, OLEDs are beginning to gradually penetrate into the fields of automobiles, Virtual Reality (VR), health lighting, and the like, revealing irreplaceable excellent characteristics thereof. Taking healthy lighting as an example, an OLED that integrates the advantages of being light, thin, flexible, free of blue light hazard, low in glare and the like is known as a fourth light source revolution product.

The light emitting principle of the OLED is that by applying direct current to the anode and the cathode, electrons and holes are respectively injected into the device from the cathode and the anode, under the action of an electric field, current carriers migrate in the auxiliary transmission material, excitons are generated in a luminescent layer in a meeting manner, and the excitons jump back to a ground state through radiation and emit light. Organic electroluminescent devices can be classified into bottom emission and top emission according to the direction of light emission. In a bottom emission device, light is emitted from a substrate, a reflective electrode is above an organic light emitting layer, and a transparent electrode is below the organic light emitting layer. The thin film transistor part in bottom emission cannot transmit light, and the light emitting area is reduced. In the top emission device, the transparent electrode is on the organic light emitting layer and the reflective electrode is under the organic light emitting layer, so light is emitted from the opposite direction of the substrate, thereby increasing the light transmission area. So the top-emitting devices are now mainly used. In order to improve the light emitting efficiency of the top-emission organic light emitting diode, the simplest and most effective method is to form a cover layer as a light extraction functional layer on a transparent electrode, adjust the optical interference distance, suppress external light reflection, suppress extinction reaction caused by surface plasmon movement, and the like.

The coating material has good properties of thermal conductivity, light transmittance, corrosion resistance, mechanical strength, adhesiveness with the substrate and the like. Generally, the organic materials are classified into inorganic materials and organic materials according to their properties, and the organic materials are widely used with advantages of low cost and easy processing. According to the reports of the existing documents, most of organic covering layers are made of amine derivative materials with high refractive index, the structures have certain steric hindrance, the materials are not easy to crystallize after being heated and cooled, and the chemical properties are stable. However, the conventional organic electroluminescent device usually uses a single-layer covering layer, and the total reflection loss cannot be reduced well, so that the improvement range of the luminous efficiency is not very large, and therefore, the problem that the organic electroluminescent device made of a reasonable and excellent covering layer material is urgently needed to be solved is solved.

Disclosure of Invention

The present invention is directed to solving the technical problems of the prior art and to providing an organic electroluminescent device having good luminous efficiency.

In order to solve the technical problem. The invention provides an organic electroluminescent device, which is sequentially provided with an anode electrode, an organic layer, a cathode electrode and a covering layer, wherein the covering layer comprises a first covering layer and a second covering layer, the refractive index of the first covering layer at 450 nm-630 nm is 1.4-1.8, and the refractive index of the second covering layer at 450 nm-630 nm is 1.9-3.0; the first cover layer contains a silicon-containing triarylamine compound represented by the following formula I,

wherein A is selected from one of formula (1) to formula (3):

r is selected from one of hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl;

Ar_aone of substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl, - - - -is a single bond or none;

L_a、L_bindependently selected from a single bond, substituted or unsubstituted arylene of C6-C25, substituted or unsubstituted C2-C20 heteroarylene;

R_athe same or different is selected from one of hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl, substituted or unsubstituted C2-C20 heteroaryl, or two adjacent R_aThe groups are bonded to form a ring structure;

R_bthe same or different is selected from one of hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl, substituted or unsubstituted C2-C20 heteroaryl, or two adjacent R_bThe groups are bonded to form a ring structure;

r is 0, 1, 2, 3 or 4; a is 0, 1, 2, 3 or 4; b is 0, 1, 2, 3 or 4.

The invention has the beneficial effects that:

the invention provides an organic electroluminescent device, which is sequentially provided with an anode electrode, a hole injection layer, a hole transport layer, a luminescent layer, an electron transport layer, an electron injection layer, a cathode electrode and a covering layer, wherein the covering layer comprises a first covering layer and a second covering layer.

Detailed Description

The following will clearly and completely describe the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of protection of the present invention.

The alkyl group in the present invention refers to a hydrocarbon group obtained by dropping one hydrogen atom from an alkane molecule, and may be a straight-chain alkyl group or a branched-chain alkyl group, and preferably has 1 to 15 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 6 carbon atoms. The straight chain alkyl group includes methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl and the like, but is not limited thereto; the branched alkyl group includes, but is not limited to, an isomeric group of isopropyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, an isomeric group of n-hexyl, an isomeric group of n-heptyl, an isomeric group of n-octyl, an isomeric group of n-nonyl, an isomeric group of n-decyl, and the like. The alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, or a tert-butyl group.

The cycloalkyl group in the present invention refers to a hydrocarbon group obtained by removing one hydrogen atom from a cycloalkane molecule, and preferably has 3 to 15 carbon atoms, more preferably 3 to 12 carbon atoms, and particularly preferably 3 to 6 carbon atoms, and examples thereof may include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, bornyl, norbornyl, and the like. The alkyl group is preferably a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group or a norbornyl group.

The aryl group in the present invention refers to a general term of monovalent group remaining after one hydrogen atom is removed from an aromatic nucleus carbon of an aromatic compound molecule, and may be monocyclic aryl group, polycyclic aryl group or condensed ring aryl group, preferably having 6 to 25 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 14 carbon atoms. The monocyclic aryl group means an aryl group having only one aromatic ring in the molecule, for example, phenyl group and the like, but is not limited thereto; the polycyclic aromatic group means an aromatic group having two or more independent aromatic rings in the molecule, for example, biphenyl group, terphenyl group and the like, but is not limited thereto; the fused ring aryl group refers to an aryl group in which two or more aromatic rings are contained in a molecule and are fused together by sharing two adjacent carbon atoms, and examples thereof include, but are not limited to, naphthyl, anthryl, phenanthryl, pyrenyl, perylenyl, fluorenyl, benzofluorenyl, triphenylene, fluoranthenyl, spirobifluorenyl, and the like. The above aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group (preferably a 2-naphthyl group), an anthryl group (preferably a 2-anthryl group), a phenanthryl group, a pyrenyl group, a perylenyl group, a fluorenyl group, a benzofluorenyl group, a triphenylene group, or a spirobifluorenyl group.

The heteroaryl group in the present invention refers to a general term of a group obtained by replacing one or more aromatic nucleus carbon atoms in an aryl group with a heteroatom, including but not limited to oxygen, sulfur, nitrogen or phosphorus atom, preferably having 1 to 25 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably 3 to 15 carbon atoms, wherein the attachment site of the heteroaryl group may be located on a ring-forming carbon atom or a ring-forming nitrogen atom, and the heteroaryl group may be a monocyclic heteroaryl group, a polycyclic heteroaryl group or a fused ring heteroaryl group. The monocyclic heteroaryl group includes pyridyl, pyrimidyl, triazinyl, furyl, thienyl, pyrrolyl, imidazolyl and the like, but is not limited thereto; the polycyclic heteroaryl group includes bipyridyl, phenylpyridyl, and the like, but is not limited thereto; the fused ring heteroaryl group includes quinolyl, isoquinolyl, indolyl, benzothienyl, benzofuranyl, benzoxazolyl, benzimidazolyl, benzothiazolyl, dibenzofuranyl, dibenzothienyl, carbazolyl, benzocarbazolyl, acridinyl, 9, 10-dihydroacridinyl, phenoxazinyl, phenothiazinyl, phenoxathiyl and the like, but is not limited thereto. The heteroaryl group is preferably a pyridyl group, a pyrimidyl group, a thienyl group, a furyl group, a benzothienyl group, a benzofuryl group, a benzoxazolyl group, a benzimidazolyl group, a benzothiazolyl group, a dibenzofuryl group, a dibenzothienyl group, a dibenzofuryl group, a carbazolyl group, an acridinyl group, a phenoxazinyl group, a phenothiazinyl group or a phenoxathiyl group.

The arylene group in the present invention refers to a general term of a divalent group remaining after two hydrogen atoms are removed from an aromatic core carbon of an aromatic compound molecule, and may be a monocyclic arylene group, a polycyclic arylene group or a condensed ring arylene group, and preferably has 6 to 25 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 14 carbon atoms. The monocyclic arylene group includes phenylene group and the like, but is not limited thereto; the polycyclic arylene group includes, but is not limited to, biphenylene, terphenylene, and the like; the condensed ring arylene group includes naphthylene, anthrylene, phenanthrylene, fluorenylene, pyrenylene, triphenylene, fluoranthenylene, phenylfluorenylene, and the like, but is not limited thereto. The arylene group is preferably a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, a fluorenylene group, or a phenylfluorenylene group.

Heteroarylene as used herein refers to the generic term for groups in which one or more of the aromatic core carbons in the arylene group is replaced with a heteroatom, including, but not limited to, oxygen, sulfur, nitrogen, or phosphorus atoms. Preferably having 6 to 25 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 15 carbon atoms, and the linking site of the heteroarylene group may be located on a ring-forming carbon atom or a ring-forming nitrogen atom, and the heteroarylene group may be a monocyclic heteroarylene group, a polycyclic heteroarylene group, or a fused ring heteroarylene group. The monocyclic heteroarylene group includes a pyridylene group, a pyrimidylene group, a triazinylene group, a furanylene group, a thiophenylene group and the like, but is not limited thereto; the polycyclic heteroarylene group includes bipyridyl idene, phenylpyridyl, etc., but is not limited thereto; the fused ring heteroarylene group includes, but is not limited to, a quinolylene group, an isoquinolylene group, an indolyl group, a benzothiophene group, a benzofuranylene group, a benzoxazolyl group, a benzimidazolylene group, a benzothiazolyl group, a dibenzofuranylene group, a dibenzothiophenylene group, a carbazolyl group, a benzocarbazolyl group, an acridinylene group, a 9, 10-dihydroacridine group, a phenoxazinyl group, a phenothiazinylene group, a phenoxathiin group and the like. The heteroaryl group is preferably a pyridylene group, pyrimidylene group, thienylene group, furylene group, benzothienylene group, benzofuranylene group, benzoxazolyl group, benzimidazolylene group, benzothiazolyl group, dibenzofuranylene group, dibenzothiophenylene group, dibenzofuranylene group, carbazolyl group, acridinylene group, phenoxazinyl group, phenothiazinylene group, phenoxathiin group.

The term "substituted …" as used herein, such as substituted alkyl, substituted cycloalkyl, substituted aryl, substituted heteroaryl, substituted arylene, substituted heteroarylene, refers to mono-or poly-substituted with groups independently selected from deuterium, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C3-C12 cycloalkyl, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C2-C15 heteroaryl, substituted or unsubstituted amine, and the like, but not limited thereto, preferably with groups selected from deuterium, methyl, ethyl, isopropyl, tert-butyl, phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, benzophenanthryl, perylenyl, pyrenyl, benzyl, fluorenyl, 9-dimethylfluorenyl, dianilinyl, dimethylamino, carbazolyl, 9-phenylcarbazolyl, acridinyl, furyl, thienyl, benzofuranyl, pyrenyl, and the like, Benzothienyl, benzoxazolyl, benzimidazolyl, benzothiazolyl, dibenzofuranyl, dibenzothienyl, phenothiazinyl, phenoxazinyl, indolyl.

The bonding to form a cyclic structure according to the present invention means that two groups are linked to each other by a chemical bond and optionally aromatized. As exemplified below:

in the present invention, the ring formed by the connection may be a five-membered ring or a six-membered ring or a condensed ring, such as phenyl, naphthyl, cyclopentenyl, cyclopentylalkyl, cyclohexanophenyl, quinolyl, isoquinolyl, dibenzothienyl, phenanthryl or pyrenyl, but is not limited thereto.

The "refractive index" as used herein refers to a refractive index at 450nm to 630nm, particularly to a refractive index at 450nm to 550nm, and particularly to a refractive index at 450 nm. Preferably, the "refractive index" of the present invention refers to the refractive index at 450nm, 550nm or 630nm, and more preferably, the "refractive index" of the present invention refers to the refractive index at 450 nm.

The organic electroluminescent device has the structure of substrate/anode/organic layer/cathode/covering layer. In the present invention, the organic layer includes one or more layers of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a hole blocking layer, an electron blocking layer, a charge generation layer, a light emission auxiliary layer, and the like. In the present invention, the cover layer includes a first cover layer and a second cover layer; wherein the first cover layer is located between the cathode and the second cover layer, or the second cover layer is located between the cathode and the first cover layer. The organic electroluminescent device of the present invention is preferably:

substrate/anode/hole transport layer/luminescent layer/electron transport layer/cathode/second cover layer/first cover layer;

substrate/anode/hole transport layer/luminescent layer/electron transport layer/electron injection layer/cathode/second cover layer/first cover layer;

substrate/anode/hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer/cathode/second cover layer/first cover layer;

substrate/anode/hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer/cathode/first cover layer/second cover layer;

substrate/anode/hole injection layer/hole transport layer/light emitting layer/electron transport layer/cathode/second cladding layer/first cladding layer.

However, the structure of the organic electroluminescent device is not limited thereto. The organic electroluminescent device can be selected and combined according to the parameter requirements of the device and the characteristics of materials, and part of organic layers can be added or omitted. For example, an electron blocking layer may be provided between the hole transport layer and the light emitting layer, a hole blocking layer may be provided between the electron transport layer and the light emitting layer, and an organic layer having the same function may be formed in a stacked structure of two or more layers.

The light emitting device of the present invention is generally formed on a substrate. The substrate may be any substrate as long as it does not change when forming an electrode or an organic layer, for example, a substrate of glass, plastic, a polymer film, silicon, or the like. When the substrate is opaque, the electrode opposite thereto is preferably transparent or translucent.

In the light-emitting device of the present invention, at least one of the anode and the cathode is transparent or translucent, and preferably, the cathode is transparent or translucent.

The anode material is preferably a material having a large work function so that holes are smoothly injected into the organic material layer, and a conductive metal oxide film, a translucent metal thin film, or the like is often used. Examples of the method for producing the film include a film (NESA or the like) made of a conductive inorganic compound containing indium oxide, zinc oxide, tin oxide, and a composite thereof, such as indium tin oxide (abbreviated as ITO) or indium zinc oxide (abbreviated as IZO), and a method using gold, platinum, silver, copper, or the like. As the anode, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof, or the like can be used. The anode may have a laminated structure of 2 or more layers, and preferably, the anode of the present invention is formed of a transparent ITO substrate.

The hole injection layer is to improve the efficiency of hole injection from the anode into the hole transport layer and the light emitting layer. The hole injection material of the present invention may be a metal oxide such as molybdenum oxide, silver oxide, vanadium oxide, tungsten oxide, ruthenium oxide, nickel oxide, copper oxide, or titanium oxide, or a low molecular weight organic compound such as a phthalocyanine-based compound or a polycyano group-containing conjugated organic material, but is not limited thereto. The hole injection layer of the present invention may be a single structure formed of a single substance, or a single-layer structure or a multi-layer structure formed of different substances.

The hole transport layer is a layer having a function of transporting holes. The hole transport material of the present invention is preferably a material having a good hole transport property, and may be selected from small molecular materials such as aromatic amine derivatives, carbazole derivatives, stilbene derivatives, triphenyldiamine derivatives, styrene compounds, butadiene compounds, and polymer materials such as poly-p-phenylene derivatives, polyaniline and derivatives thereof, polythiophene and derivatives thereof, polyvinylcarbazole and derivatives thereof, polysilane and derivatives thereof, but is not limited thereto. The hole transport layer of the present invention may be a single structure formed of a single substance, or a single-layer structure or a multi-layer structure formed of different substances.

The light-emitting layer is a layer having a light-emitting function. As for the light emitting layer of the organic electroluminescent device of the present invention, a red light emitting material, a green light emitting material, or a blue light emitting material can be used as the light emitting material, and two or more light emitting materials can be mixed and used if necessary. The light-emitting material may be a host material alone or a mixture of a host material and a dopant material, and the light-emitting layer is preferably formed using a mixture of a host material and a dopant material.

Preferably, the host material of the present invention is selected from 4,4' -bis (9-carbazole) biphenyl (abbreviated as CBP), 9, 10-bis (2-naphthyl) anthracene (abbreviated as ADN), 4-bis (9-carbazolyl) biphenyl (abbreviated as CPB), 9' - (1, 3-phenyl) bis-9H-carbazole (abbreviated as mCP), 4' -tris (carbazol-9-yl) triphenylamine (abbreviated as TCTA), 9, 10-bis (1-naphthyl) anthracene (abbreviated as. alpha. -AND), N ' -bis- (1-naphthyl) -N, N ' -diphenyl- [1,1':4', 1':4', 1' -tetrabiphenyl ] -4, 4' -diamino (abbreviated as 4P-NPB), 1,3, 5-tris (9-carbazolyl) benzene (abbreviated as TCP), which may be a single layer structure composed of a single substance or a single layer structure or a multilayer structure composed of different substances, and in addition to the above materials and combinations thereof, the light-emitting layer host material may include other known materials suitable for a light-emitting layer, for example, green light-emitting layer host materials represented by GH-1 to GH-12 as follows:

the guest material of the light-emitting layer of the present invention may include one material or a mixture of two or more materials, and the light-emitting material is classified into a blue light-emitting material, a green light-emitting material, and a red light-emitting material. Preferably, the light-emitting material of the present invention is a green light-emitting material, and the guest of the green light-emitting layer is selected from tris (2-phenylpyridine) iridium (ir (ppy)₃) Bis (2-phenylpyridine) iridium acetylacetonate (Ir (ppy)₂(acac)) and the like. In addition to the above materials, the light-emitting layer guest material may include other known materials suitable for use as a light-emitting layer, such as green light-emitting layer guest materials as represented by GD-1 to GD-10 below:

the doping ratio of the host material and the guest material of the light-emitting layer may be preferably varied depending on the materials used, and the mass percentage of the guest material of the light-emitting layer is usually 0.01 to 20%, preferably 0.1 to 15%, and more preferably 1 to 10%.

The electron transport layer is a layer having a function of transporting electrons, and functions to inject electrons and balance carriers. The electron transport material can be selected from metal complexes of known oxadiazole derivatives, anthraquinone dimethane and derivatives thereof, benzoquinone and derivatives thereof, naphthoquinone and derivatives thereof, anthraquinone and derivatives thereof, tetracyanoanthraquinone dimethane and derivatives thereof, fluorenone derivatives, diphenoquinone derivatives, 8-hydroxyquinoline and derivatives thereof, and the electron transport layer can be a single structure formed by a single substance or a single-layer structure or a multi-layer structure formed by different substances. In addition to the above materials, the electron transport layer material may also include other known materials suitable for use as an electron transport layer. Preferably, the electron transport layer according to the present invention is selected from a mixture of one or more of the following compounds:

the film thicknesses of the hole transporting layer and the electron transporting layer may be selected as appropriate depending on the materials used, and may be selected so as to achieve appropriate values of the driving voltage and the light emission efficiency. Therefore, the film thicknesses of the hole transporting layer and the electron transporting layer are, for example, 1nm to 1 μm, preferably 2nm to 500nm, and more preferably 5nm to 200 nm.

The electron injection layer material is a material that assists the injection of electrons from the cathode into the organic layer. The best choice of material is usually a corrosion resistant high work function metal as the cathode, with Al and Ag being common materials. Electron injection materials have been developed to date and include two types; one type is an alkali metal compound, such as lithium oxide (Li)₂O), lithium boron oxide (LiBO)₂) Cesium carbonate (Cs)₂CO₃) Potassium silicate (K)₂SiO₃) And the optimal thickness is generally 0.3-1.0 nm, and the device formed by the compounds can reduce the driving voltageAnd improves device efficiency. In addition, acetate compounds of alkali metals (CH)₃COOM, where M is Li, Na, K, Rb, Cs) also have similar effects. Another class is alkali metal fluorides (MF, where M is Li, Na, K, Rb, Cs), and if Al is used as the cathode material, the optimum thickness of these materials is typically less than 1.0 nm. The electron injection layer according to the present invention may be selected from LiF.

In the cathode material, a metal material having a small work function is generally preferable in order to inject electrons into the electron injection/transport layer or the light-emitting layer. For example, metals such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like, alloys of 2 or more of these metals, or alloys of 1 or more of these metals and 1 or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, graphite, or graphite intercalation compounds, and the like can be used. Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, and calcium-aluminum alloy. The cathode may have a laminated structure of 2 or more layers. The cathode can be prepared by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. Among them, when light emission of the light-emitting layer is extracted from the cathode, the light transmittance of the cathode is preferably more than 10%. It is also preferable that the sheet resistivity of the cathode is several hundred Ω/□ or less, and the film thickness is usually 10nm to 1 μm, preferably 50 to 200 nm.

Preferably, the cathode of the invention uses Ag or Mg-Ag alloy or thin Al.

The covering layer material is used for reducing the total emission loss and waveguide loss in the OLED device and improving the light extraction efficiency. The covering layer of the invention comprises a first covering layer and a second covering layer, wherein the refractive index of the first covering layer at 450 nm-630 nm is between 1.4 and 1.8, and the refractive index of the second covering layer at 450 nm-630 nm is between 1.9 and 3.0; the first cover layer contains a silicon-containing triarylamine compound represented by the following formula I,

wherein A is selected from one of formula (1) to formula (3):

r is 0, 1, 2, 3 or 4; a is 0, 1, 2, 3 or 4; b is 0, 1, 2, 3 or 4.

Preferably, Ar is_aOne selected from the following groups:

wherein R is₁₂One selected from methyl, n-propyl, n-butyl, isopropyl, tert-butyl, phenyl, tolyl, biphenyl and naphthyl;

R_pselected from deuterium, methyl, ethylOne of a phenyl group, an n-propyl group, an n-butyl group, an isopropyl group, an isobutyl group, a tert-butyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a camphyl group, a norbornyl group, a phenyl group, a tolyl group, a biphenyl group, a terphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a triphenylene group, an acridine group, a spirobifluorenyl group, a 9, 9-dimethylfluorenyl group, a 9, 9-diphenylfluorenyl group, a 9-phenylcarbazolyl group, a pyrenyl group, an indolyl group, a benzothienyl group, a benzofuranyl group, a dibenzothiophenyl group;

q is 0, 1 or 2;

L_cselected from one of the following formulas:

preferably, L_aSelected from single bond or one of the following groups:

preferably, R_aAnd R_bIndependently selected from one of hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, camphanyl, norbornyl, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, fluorenyl, 9-diphenylfluorenyl and spirofluorenyl;

r is selected from hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, camphanyl, norbornyl, phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, triphenylene, perylenyl, pyrenyl, benzyl, fluorenyl, 9-dimethylfluorenyl, carbazolyl, 9-phenylcarbazolyl, acridinyl, dibenzofuranyl and dibenzothiophenyl.

Preferably, the silicon-containing triarylamine compound represented by the formula I is selected from any one of the following chemical structures:

preferably, the second cover layer contains a triarylamine compound containing spirofluorene represented by the following formula ii:

wherein R is₁、R₂、R₃Independently selected from one of hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl;

L₁、L₂、L₃independently selected from single bond, substituted or unsubstituted C6-C25 arylene, substituted or unsubstitutedOne of substituted C2-C20 heteroarylenes;

X₁selected from O, S or NR₀Wherein R is₀One selected from substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl;

R₄one selected from hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl;

x is selected from O, S, NR₀₀Or CR₁₁R₁₁Wherein R is₀₀One selected from substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl, R₁₁One selected from hydrogen, substituted or unsubstituted aryl of C6-C25, and substituted or unsubstituted heteroaryl of C2-C20;

R₅one selected from hydrogen, deuterium, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C6-C25 aryl and substituted or unsubstituted C2-C20 heteroaryl;

m is selected from 0, 1, 2, 3 or 4; n is selected from 0, 1, 2, 3 or 4; p is selected from 0, 1, 2, 3 or 4; q is selected from 0, 1, 2, 3 or 4; o is selected from 0, 1, 2, 3 or 4;

when m is greater than 1, each R₁Same or different, adjacent R₁Can form a benzene ring; when n is greater than 1, each R₂Same or different, adjacent R₂Can form a benzene ring; when p is greater than 1, each R₃Same or different, adjacent R₃Can form a benzene ring; when q is greater than 1, each R₄Same or different, adjacent R₄Can form a benzene ring or a naphthalene ring; when o is greater than 1, each R₅Same or different, adjacent R₅Can form benzene ring.

Preferably, said R is₁、R₂、R₃Independently selected from hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantineOne of alkyl, camphanyl, norbornyl, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothienyl, carbazolyl, fluorenyl, 9-diphenylfluorenyl and spirofluorenyl;

m is selected from 0, 1 or 2; n is selected from 0, 1 or 2; p is selected from 0, 1 or 2.

Preferably, X is₁Selected from O, S or NR₀Wherein R is₀One selected from methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, phenyl, tolyl, biphenyl and naphthyl; q is selected from 0, 1, 2, 3 or 4;

R₄selected from hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, cyclopentyl or one of the following substituents:

preferably, the

One selected from the following groups:

preferably, said R is₅One selected from hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl, bornyl, norbornyl or the following substituents:

x is selected from O, S, NR₀₀Or CR₁₁R₁₁Wherein R is₀₀One selected from phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothienyl and fluorenyl, R₁₁Is the same as orVariously selected from one of hydrogen, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl;

o is selected from 0, 1 or 2.

Preferably, said L₁、L₂、L₃Independently selected from a single bond or any one of the following groups:

preferably, the triarylamine compound containing spirofluorene represented by formula II is selected from any one of the following chemical structures:

the order and number of layers to be stacked and the thickness of each layer can be appropriately selected in consideration of the light emission efficiency and the lifetime of the device.

The method for forming each layer in the organic electroluminescent device is not particularly limited, and any one of vacuum evaporation, spin coating, vapor deposition, blade coating, laser thermal transfer, electrospray coating, slit coating, and dip coating may be used, and in the present invention, vacuum evaporation is preferably used.

In the organic electroluminescent device according to the present invention, the capping layer includes a first capping layer and a second capping layer, which may be formed as separate films or may be mixed with other materials to form a film. The sum of the thicknesses of the first and second cover layers is preferably 30nm to 120 nm. The first covering layer and the second covering layer can be evaporated in sequence, the first covering layer can be evaporated first, then the second covering layer can be evaporated, and then the first covering layer can be evaporated.

The organic electroluminescent device can be widely applied to the fields of panel display, lighting sources, flexible OLEDs, electronic paper, organic solar cells, organic photoreceptors or organic thin film transistors, signs, signal lamps and the like.

The invention relates to a silicon-containing triarylamine compound represented by a formula I and a spirofluorene-containing triarylamine compound represented by a formula II, wherein the corresponding compounds can be obtained by the following methods:

the silicon-containing triarylamine compound shown in the formula I can be obtained by a Buchwald reaction, namely, under the nitrogen atmosphere, adding raw materials, a catalyst, an organic base, a ligand and a solution, and reacting at a corresponding temperature to obtain a corresponding compound.

The triarylamine compound containing spirofluorene shown in formula II can be obtained by a Buchwald reaction, namely, under the nitrogen atmosphere, raw materials, a catalyst, organic base, a ligand and a solution are added, and the reaction is carried out at a corresponding temperature to obtain a corresponding compound.

The sources of the raw materials used in the above-mentioned various reactions are not particularly limited in the present invention, and the compounds represented by formula I and formula II described in the present invention can be obtained using commercially available raw materials or by preparation methods well known to those skilled in the art.

The present invention is not particularly limited to the above-mentioned reaction, and a conventional reaction known to those skilled in the art may be used.

The invention is explained in more detail by the following examples, without wishing to restrict the invention accordingly. Based on this description, one of ordinary skill in the art will be able to practice the invention and prepare other compounds and devices according to the invention within the full scope of the disclosure without undue inventive effort.

Description of raw materials, reagents and characterization equipment:

the raw materials used in the following examples are not particularly limited, and may be commercially available products or prepared by methods known to those skilled in the art.

The mass spectrum uses British Watts G2-Si quadrupole rod series time-of-flight high resolution mass spectrometer, chloroform is used as solvent;

the elemental analysis was carried out by using a Vario EL cube type organic element analyzer of Elementar, Germany, and the sample mass was 5 to 10 mg.

EXAMPLE 1 Synthesis of Compound 1-1

Step 1: synthesis of intermediate A-1

To a 1L reaction flask were added toluene (600mL), a-1(20.00g, 0.06mol), b-1(17.35g, 0.06mol), palladium acetate (0.21g, 0.95mmol), sodium tert-butoxide (11.53g, 0.12mol), and tri-tert-butylphosphine (8mL in toluene) in that order under nitrogen. And reacted under reflux for 2 hours. After the reaction was stopped, the mixture was cooled to room temperature, filtered through celite, the filtrate was concentrated, recrystallized from methanol, filtered with suction and rinsed with methanol to give a recrystallized solid, intermediate a-1(25.03g, 77% yield) with a solid purity ≧ 99.6% by HPLC.

Step 2: synthesis of Compound 1-1

Under nitrogen protection, a 1L reaction flask was charged with toluene solvent (600ml), c-1(9.32g, 40mmol), intermediate A-1(21.67g, 40mmol), and Pd in that order₂(dba)₃(366mg, 0.40mmol), BINAP (0.67g, 1.08mmol) and sodium tert-butoxide (4.81g, 50mmol), dissolved with stirring and reacted under reflux for 24 hours under nitrogen, after completion of the reaction, the reaction solution was washed with dichloromethane and distilled water and extracted by separation. The organic layer was dried over anhydrous magnesium sulfate, filtered, and then the solvent was removed, followed by washing with cyclohexane: and (3) separating, purifying and refining the ethyl acetate ═ 9:1 by column chromatography as an eluent to finally obtain the compound 1-1(18.32g, the yield is 66%), and the solid purity is ≧ 99.4% by HPLC detection.

Mass spectrum m/z: 693.2898 (theoretical value: 693.2852). Theoretical element content (%) C₅₁H₃₉NSi: c, 88.27; h, 5.66; n, 2.02 measured element content (%): c, 88.28; h, 5.63; and N, 2.06.

EXAMPLE 2 Synthesis of Compounds 1 to 13

Compound 1-13(18.97g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.5% or more by HPLC. Mass spectrum m/z: 667.2713 (theoretical value: 667.2695). Theoretical element content (%) C₄₉H₃₇NSi: c, 88.11; h, 5.58; n, 2.10 measured elemental content (%): c, 88.14; h, 5.55; and N, 2.10.

EXAMPLE 3 Synthesis of Compounds 1 to 17

Compound 1-17(18.97g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.7% or more by HPLC. Mass spectrum m/z: 707.2686 (theoretical value: 707.2644). Theoretical element content (%) C₅₁H₃₇NOSi: c, 86.53; h, 5.27; n, 1.98 measured elemental content (%): c, 86.55; h, 5.28; and N, 1.95.

EXAMPLE 4 Synthesis of Compounds 1 to 38

Compound 1-38(18.17g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.3% or more by HPLC. Mass spectrum m/z: 698.3198 (theoretical value: 698.3166). Theoretical element content (%) C₅₁H₃₄D₅NSi: c, 87.63; h, 6.34; n, 2.00 measured element content (%): c, 87.65; h, 6.32; n, 1.98.

EXAMPLE 5 Synthesis of Compounds 1 to 45

Compound 1-45(21.33g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.5% or more by HPLC. Mass spectrum m/z: 783.3359 (theoretical value: 783.3321). Theoretical element content (%) C₅₈H₄₅NSi: c, 88.85; h, 5.79; n, 1.79 measured elemental content (%): c, 88.87; h, 5.78; n, 1.72.

EXAMPLE 6 Synthesis of Compounds 1 to 50

Compound 1-50(21.63g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.4% or more by HPLC. Mass spectrum m/z: 857.3543 (theoretical value: 857.3478). Theoretical element content (%) C₆₄H₄₇NSi: c, 89.57; h, 5.52; n, 1.63 measured elemental content (%): c, 89.55; h, 5.54; n, 1.68.

EXAMPLE 7 Synthesis of Compounds 1 to 66

Compound 1-66(23.59g) was synthesized by the method described for Compound 1-1 above, and had a solid purity ≧ 98.7% by HPLC. Mass spectrum m/z: 906.3498 (theoretical value: 906.3430). Theoretical element content (%) C₆₇H₄₆N₂Si: c, 88.71; h, 5.11; n, 3.09 measured elemental content (%): c, 88.73; h, 5.16; and N, 3.07.

EXAMPLE 8 Synthesis of Compounds 1 to 81

Compound 1-81(21.23g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.8% or more by HPLC. Mass spectrum m/z: 855.3346 (theoretical value: 855.3321. theoretical element content (%) C₆₄H₄₅NSi: c, 89.79; h, 5.30; n, 1.64 measured elemental content (%): c, 89.75; h, 5.34; n, 1.63.

EXAMPLE 9 Synthesis of Compounds 1 to 118

Compound 1-118(20.50g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.5% or more by HPLC. Mass spectrum m/z: 853.3188 (theoretical value: 853.3165). Theoretical element content (%) C₆₄H₄₃NSi: c, 90.00; h, 5.07; n, 1.64 measured elemental content (%): c, 90.00; h, 5.09; n, 1.62.

EXAMPLE 10 Synthesis of Compounds 1-153

Compound 1-153(19.96g) was synthesized by the method described for Compound 1-1 above, and had a solid purity of 99.3% or more by HPLC. Mass spectrum m/z: 817.3793 (theoretical value: 817.3740). Theoretical element content (%) C₅₉H₅₁NOSi: c, 86.62; h, 6.28; n, 1.71 measured elemental content (%): c, 86.65; h, 6.25; n, 1.66.

The compounds thus obtained by example 2 to example 10 as above are as follows:

EXAMPLE 11 Synthesis of Compound 2-1

Step 1: synthesis of intermediate B-1

Toluene (600mL), M-1(12.61g, 0.06mol), n-1(23.64g, 0.06mol), palladium acetate (0.18g, 0.80mmol), sodium tert-butoxide (8.65g, 0.09mol) and tri-tert-butylphosphine (11mL of a 1.0M solution in toluene) were added sequentially to a 1L reaction flask under nitrogen protection and reacted at 100 ℃ for 2 hours. After the reaction is stopped, the mixture is cooled to room temperature, filtered by using kieselguhr, the filtrate is concentrated, recrystallized by using methanol, filtered by suction and rinsed by using methanol to obtain a recrystallized solid, and the intermediate B-1(23.90g, the yield is 76%) is obtained, and the purity of the solid is not less than 99.5% by HPLC (high performance liquid chromatography).

Step 2: synthesis of Compound 2-1

A1L reaction flask was charged with toluene solvent (600ml), p-1(7.91g, 32mmol), intermediate B-1(16.77g, 32mmol), and Pd in that order under nitrogen protection₂(dba)₃(458mg, 0.5mmol), BINAP (0.20g, 3.2mmol) and sodium tert-butoxide (7.68g, 80mmol), dissolved with stirring and reacted under reflux for 24 hours under nitrogen, after completion of the reaction, the reaction solution was washed with dichloromethane and distilled water and extracted by separation. The organic layer was dried over anhydrous magnesium sulfate, filtered, and then the solvent was removed, followed by washing with cyclohexane: separating, purifying and refining ethyl acetate 10:1 by column chromatography as eluent to obtain solid compound 2-1(19.68g, yield 80%), and purity ≧ 99.8% by HPLC.

Mass spectrum m/z: 690.2385 (theoretical value: 690.2307). Theoretical element content (%) C₅₀H₃₀N₂O₂: c, 86.94; h, 4.38; n, 4.06 measured elemental content (%): c, 86.97; h, 4.33; and N, 4.13.

EXAMPLE 12 Synthesis of Compounds 2 to 4

Compound 2-4(17.66g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.4% or more by HPLC. Mass spectrum m/z: 766.2629 (theoretical value: 766.2620). Theoretical element content (%) C₅₆H₃₄N₂O₂: c, 87.71; h, 4.47; n, 3.65 measured elemental content (%): c, 87.73; h, 4.45; and N, 3.72.

EXAMPLE 13 Synthesis of Compounds 2 to 33

Compound 2-33(16.17g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.7% or more by HPLC. Mass spectrum m/z: 664.2172 (theoretical value: 664.2151). Theoretical element content (%) C₄₈H₂₈N₂O₂: c, 86.73; h, 4.25; n, 4.21 measured elemental content (%): c, 86.78; h, 4.20; n, 4.19.

EXAMPLE 14 Synthesis of Compounds 2 to 46

Compound 2-46(17.87g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.8% or more by HPLC. Mass spectrum m/z:706.2095 (theoretical value: 706.2079). Theoretical element content (%) C₅₀H₃₀N₂And OS: c, 84.96; h, 4.28; n, 3.96 measured elemental content (%): c, 84.97; h, 4.27; and N, 3.88.

EXAMPLE 15 Synthesis of Compounds 2 to 77

Compound 2-77(18.89g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.7% or more by HPLC. Mass spectrum m/z: 802.3565 (theoretical value: 802.3559). Theoretical element content (%) C₅₈H₄₆N₂O₂: c, 86.75; h, 5.77; n, 3.49 measured elemental content (%): c, 86.77; h, 5.75; and N, 3.47.

EXAMPLE 16 Synthesis of Compounds 2 to 81

Compound 2-81(19.27g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.9% or more by HPLC. Mass spectrum m/z: 802.3573 (theoretical value: 802.3559). Theoretical element content (%) C₅₈H₄₆N₂O₂: c, 86.75; h, 5.77; n, 3.49 measured elemental content (%): c, 86.77; h, 5.71; and N, 3.53.

EXAMPLE 17 Synthesis of Compounds 2 to 87

Compound 2-87(21.79g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.4% or more by HPLC. Mass spectrum m/z: 883.4199 (theoretical value: 883.4186). Theoretical element content (%) C₆₄H₄₅D₅N₂O₂: c, 86.94; h, 6.27; n, 3.17 measured elemental content (%): c, 86.96; h, 6.33; n, 3.11.

EXAMPLE 18 Synthesis of Compounds 2 to 129

Compound 2-129(18.53g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.6% or more by HPLC. Mass spectrum m/z: 824.3436 (theoretical value: 824.3403). Theoretical element content (%) C₆₀H₄₄N₂O₂: c, 87.35; h, 5.38; n, 3.40 measured elemental content (%): c, 87.33; h, 5.35; n, 3.43.

EXAMPLE 19 Synthesis of Compounds 2 to 182

By using the compounds as described above2-1, Compound 2-182(19.39g) was synthesized with a solid purity ≧ 99.8% by HPLC. Mass spectrum m/z: 877.4086 (theoretical value: 877.4032). Theoretical element content (%) C₆₄H₅₁N₃O: c, 87.54; h, 5.85; n, 4.79 measured elemental content (%): c, 87.50; h, 5.90; n, 4.78.

EXAMPLE 20 Synthesis of Compounds 2-199

Compound 2-199(20.72g) was synthesized by the method described for Compound 2-1 above, and had a solid purity of 99.5% or more by HPLC. Mass spectrum m/z: 840.3185 (theoretical value: 840.3141). Theoretical element content (%) C₆₃H₄₀N₂O: c, 89.97; h, 4.79; n, 3.33 measured elemental content (%): c, 89.99; h, 4.74; and N, 3.36.

The compounds thus obtained by example 12 to example 20 as above were as follows:

refractive index (n) was measured by j.a.woollam, usa, model: measuring by an M-2000 spectrum ellipsometer, wherein the measurement is in an atmospheric environment, and the scanning range of the ellipsometer is 245-1000 nm; the size of the glass substrate is 200 multiplied by 200mm, and the thickness of the material film is 20-60 nm. The results of refractive index tests of the silicon-containing triarylamine compound and the spirofluorene-containing triarylamine compound of the present invention are shown in table 1 below.

TABLE 1 photophysical characteristic test of light emitting device

Comparative example 1 device preparation example:

the organic electroluminescent device is prepared by a vacuum thermal evaporation method. The experimental steps are as follows: repeatedly washing the ITO-Ag-ITO substrate with a glass cleaning agent, then washing the ITO-Ag-ITO substrate in distilled water for 2 times, ultrasonically washing for 15 minutes, after the washing with the distilled water is finished, ultrasonically washing solvents such as isopropanol, acetone and methanol in sequence, drying at 120 ℃, and conveying to an evaporation plating machine.

A hole injection layer compound HIL/40nm, a hole transport layer HT/40nm, a luminescent layer (a main body GH-1: GH-2: GD-1 (45%: 45%: 10% mixed))/30 nm, an electron transport layer ET/30nm, an electron injection layer LiF/1nm and a cathode Mg-Ag (Mg: Ag doping ratio is 9:1)/25nm are evaporated on the prepared ITO-Ag-ITO electrode in a layer-by-layer vacuum evaporation mode, and then a cover layer compound is evaporated on a cathode layer for 2-1/50 nm.

[ application examples 1 to 10]

Application example 1: the organic electroluminescent device is prepared by a vacuum thermal evaporation method. The experimental steps are as follows: repeatedly washing the ITO-Ag-ITO substrate with a glass cleaning agent, then washing the ITO-Ag-ITO substrate in distilled water for 2 times, ultrasonically washing for 15 minutes, after the washing with the distilled water is finished, ultrasonically washing solvents such as isopropanol, acetone and methanol in sequence, drying at 120 ℃, and conveying to an evaporation plating machine.

A hole injection layer compound HIL/40nm, a hole transport layer HT/40nm, a luminescent layer (a main body GH-1: GH-2: GD-1 (45%: 45%: 10% mixed))/30 nm, an electron transport layer ET/30nm, an electron injection layer LiF/1nm and a cathode Mg-Ag (Mg: Ag doping ratio is 9:1)/25nm are evaporated on an ITO-Ag-ITO electrode which is prepared in advance in a layer-by-layer vacuum evaporation mode, a second covering layer compound 2-1/20nm and a first covering layer compound 1-1/30nm are evaporated on a cathode layer.

Application example 2: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with compound 1-13 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with compound 2-4 of the present invention.

Application example 3: the first overlayer compound 1-1 in the organic electroluminescent device was replaced with compound 1-17 and the second overlayer compound 2-1 in the organic electroluminescent device was replaced with compound 2-33 of the present invention.

Application example 4: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with compound 1-38 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with compound 2-46 of the present invention.

Application example 5: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with compound 1-45 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with compound 2-77 of the present invention.

Application example 6: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with the compound 1-50 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with the compound 2-81 of the present invention.

Application example 7: the first overlayer compound 1-1 in the organic electroluminescent device was replaced with compounds 1-66 and the second overlayer compound 2-1 in the organic electroluminescent device was replaced with compounds 2-87 of the invention.

Application example 8: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with the compounds 1-81 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with the compounds 2-129 of the present invention.

Application example 9: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with compound 1-118 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with compound 2-182 of the present invention.

Application example 10: the first capping layer compound 1-1 in the organic electroluminescent device was replaced with compound 1-153 and the second capping layer compound 2-1 in the organic electroluminescent device was replaced with compound 2-199 according to the present invention.

The test software, computer, K2400 digital source meter manufactured by Keithley corporation, usa, and PR788 spectral scanning luminance meter manufactured by Photo Research corporation, usa were combined into a combined IVL test system to test the luminous efficiency and CIE color coordinates of the organic electroluminescent device.

The results of the light emission characteristic test of the obtained organic electroluminescent device are shown in table 1. Table 1 shows the results of the test of the light emitting characteristics of the light emitting devices prepared by the compounds prepared in the examples of the present invention and the comparative materials.

Table 1 test of light emitting characteristics of light emitting device

As can be seen from the results in table 1, the organic electroluminescent device of the present invention has better improved light emitting efficiency than that of comparative example 1 by selecting the double-layered cover layer formed by two materials with different refractive indexes.

It should be understood that the present invention has been particularly described with reference to particular embodiments thereof, but that various changes in form and details may be made therein by those skilled in the art without departing from the principles of the invention and, therefore, within the scope of the invention.

Claims

1. An organic electroluminescent device, which is provided with an anode electrode, an organic layer, a cathode electrode and a covering layer in sequence, and is characterized in that the covering layer comprises a first covering layer and a second covering layer, wherein the refractive index of the first covering layer at 450 nm-630 nm is 1.4-1.8, and the refractive index of the second covering layer at 450 nm-630 nm is 1.9-3.0; the first cover layer contains a silicon-containing triarylamine compound represented by the following formula I,

wherein A is selected from one of formula (1) to formula (3):

r is 0, 1, 2, 3 or 4; a is 0, 1, 2, 3 or 4; b is 0, 1, 2, 3 or 4.

2. The organic electroluminescent device according to claim 1, wherein the Ar is Ar_aOne selected from the following groups:

R_pselected from deuterium, methyl, ethyl, n-propyl, n-butyl, isopropylOne of isobutyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, bornyl, norbornyl, phenyl, tolyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, triphenylene, acridinyl, spirobifluorenyl, 9-dimethylfluorenyl, 9-diphenylfluorenyl, 9-phenylcarbazolyl, pyrenyl, indolyl, benzothienyl, benzofuranyl, dibenzothienyl, and dibenzofuranyl;

q is 0, 1 or 2;

L_cone selected from the following groups:

3. the organic electroluminescent device of claim 1, wherein L is_aSelected from single bond or one of the following groups:

4. the organic electroluminescent device of claim 1, wherein R is_aAnd R_bIndependently selected from one of hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, camphanyl, norbornyl, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, fluorenyl, 9-diphenylfluorenyl and spirofluorenyl;

5. The organic electroluminescent device as claimed in claim 1, wherein the silicon-containing triarylamine compound represented by formula i is selected from any one of the following chemical structures:

6. the organic electroluminescent device as claimed in claim 1, wherein the second capping layer contains a triarylamine-containing compound having spirofluorene represented by the following formula ii:

L₁、L₂、L₃independently selected from one of single bond, substituted or unsubstituted C6-C25 arylene, substituted or unsubstituted C2-C20 heteroarylene;

when m is greater than 1, each R₁Same or different, adjacent R₁Can form a benzene ring; when n is largeAt 1, each R₂Same or different, adjacent R₂Can form a benzene ring; when p is greater than 1, each R₃Same or different, adjacent R₃Can form a benzene ring; when q is greater than 1, each R₄Same or different, adjacent R₄Can form a benzene ring or a naphthalene ring; when o is greater than 1, each R₅Same or different, adjacent R₅Can form benzene ring.

7. The organic electroluminescent device according to claim 6, wherein R is₁、R₂、R₃Independently selected from one of hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl, adamantyl, camphanyl, norbornyl, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, fluorenyl, 9-diphenylfluorenyl and spirofluorenyl;

8. The organic electroluminescent device according to claim 6, wherein X is₁Selected from O, S or NR₀Wherein R is₀One selected from methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, phenyl, tolyl, biphenyl and naphthyl; q is selected from 0, 1, 2, 3 or 4;

9. the organic electroluminescent device according to claim 6, wherein R is₅Selected from hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl, bornyl, norbornyl or a group such asOne of the following substituents:

x is selected from O, S, NR₀₀Or CR₁₁R₁₁Wherein R is₀₀One selected from phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl, naphthyl, dibenzofuranyl, dibenzothienyl and fluorenyl, R₁₁The same or different is selected from one of hydrogen, phenyl, pentadeuterated phenyl, tolyl, biphenyl, terphenyl and naphthyl;

o is selected from 0, 1 or 2.

10. The organic electroluminescent device according to claim 6, wherein L is₁、L₂、L₃Independently selected from a single bond or any one of the following groups: