Aromatic amine compound and organic electroluminescent device containing the same

Abstract

The present invention discloses an aromatic amine compound and an organic electroluminescent device comprising the same. The structure of the aromatic amine compound is shown in the general formula (1): The compound of the present invention has excellent hole transport ability and exciton blocking ability. When the aromatic amine compound of the present invention is used to form the light-emitting layer auxiliary layer material of the organic electroluminescent device, the device efficiency can be improved and the life can be extended at the same time, especially the device efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and in particular to an aromatic amine compound and an organic electroluminescent device containing the same. Background Art

[0002] The carriers (holes and electrons) in an organic electroluminescent device (OLED) are injected into the device from the two electrodes of the device under the drive of an electric field, and meet and recombine in the organic light-emitting layer to emit light. High-performance organic electroluminescent devices require various organic functional materials to have good photoelectric properties. For example, as a charge transport material, it is required to have good carrier mobility. The injection and transport properties of the hole injection layer materials and hole transport layer materials used in existing organic electroluminescent devices are relatively weak, and the hole injection and transport rates do not match the electron injection and transport rates, resulting in a large offset in the recombination area, which is not conducive to the stability of the device. Therefore, how to adjust the balance of holes and electrons and adjust the recombination area has always been an important topic in this field.

[0003] Blue organic electroluminescent devices have always been the weak point in the development of full-color OLEDs. So far, the efficiency and life of blue light devices have been difficult to be comprehensively improved. Therefore, how to improve the performance of such devices is still a crucial issue and challenge facing this field. At present, most of the blue light host materials used in the market are electron-biased hosts. Due to the preferential injection of holes at low current density, the pressure on the hole transmission side is relieved to a certain extent. As the current density increases, the amount of electron injection will increase, resulting in the shift of the recombination area to the hole side, and the pressure on the hole side is increasing. In order to prevent the excitons from being transferred to the hole side, the luminescent auxiliary layer materials are required to effectively block the excitons and efficiently transfer the holes to the luminescent layer. At present, most of the luminescent auxiliary layer materials are traditional aromatic amine structures, and the side chains are selected as carbazole groups or dibenzofuran groups. The anti-exciton stability of this type of structure still cannot meet the demand, and the hole mobility at high current density still needs to be improved, so as to ensure the carrier balance of the luminescent layer and prevent the recombination area from shifting to the hole transmission side due to insufficient holes, resulting in reduced device efficiency and shortened life. Summary of the invention

[0004] In view of the above-mentioned problems existing in the prior art, the applicant of the present invention provides an aromatic amine compound. The organic compound of the present invention has excellent hole transport capability (especially hole mobility at high current density) and exciton blocking capability. When the aromatic amine compound of the present invention is used to form the light-emitting auxiliary layer material of an organic electroluminescent device, the device efficiency can be improved and the life can be extended at the same time, especially the device efficiency is significantly improved.

[0005] The technical solution of the present invention is as follows: an aromatic amine compound, the structure of which is shown in general formula (1):

[0006]

[0007] In the general formula (1), Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, a substituted or unsubstituted terphenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted phenanthrenyl, a substituted or unsubstituted indenyl, or a substituted or unsubstituted piperonyl;

[0008] The m and n are represented as 1, 2 or 3;

[0009] The R 1 represents phenyl, naphthyl, dibenzofuranyl, benzofuranyl or furanyl;

[0010] The R 2 It is represented by the structure shown in general formula (2) or general formula (3), and general formula (2) and general formula (3) are connected to the a and b, b and c, or c and d sites of general formula (1) through the * site in a ring;

[0011]

[0012] L 1 , L 2 Each independently represents a direct bond, a phenylene group, a naphthylene group or a biphenylene group;

[0013] In the general formula (3), X represents an oxygen atom or N(R);

[0014] The R represents phenyl, naphthyl or biphenyl;

[0015] The substituent of the "substituted or unsubstituted" group is selected from one or more of a deuterium atom, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a naphthyl group, a biphenyl group, a benzofuranyl group, a dibenzofuranyl group, and a furanyl group.

[0016] The present invention also provides an organic electroluminescent device, which comprises an anode, a hole transport region, a light emitting region, an electron transport region and a cathode in sequence, wherein the hole transport region contains the aromatic amine compound.

[0017] The beneficial technical effects of the present invention are:

[0018] (1) The aromatic amine compounds of the present invention, wherein the carbazole cyclic group and the amine group are in the meta position, and the ortho position of the carbazole cyclic group has a specific type of substituent. Since the carbazole group adopts a cyclic manner to increase the stability of the carbazole group, the ortho position has a substituent that makes the conformation of carbazole more stable. Furthermore, the amine group is connected with a specific type of group. Therefore, the compounds of the present invention have a more excellent exciton blocking ability, so that the excitons are better localized in the luminescent region, ensuring that the exciton concentration in the luminescent region is high, thereby improving the luminescent efficiency.

[0019] The difference between the present invention and CN110577511A is that the carbazole group is modified by ring-bonding, and the difference between the present invention and CN110317184A is that the connecting group on the amine group is improved. Through these improvements, the compounds of the present invention have better exciton blocking ability and hole mobility under high current density. When applied to devices, they have excellent device life while improving device efficiency.

[0020] (2) The connection mode and specific types of groups of the compounds of the present invention ensure the formation of differentiated carrier conduction energy levels within the aromatic amine molecular structure, thereby forming different carrier conduction channels, which is beneficial to the carrier injection and conduction between the combinations of materials with different energy levels, and is beneficial to obtaining the interface stability between the compounds of the present invention and the adjacent layer materials, thereby facilitating the good driving life of the application device.

[0021] (3) Since the compound of the present invention has a stable structure, when hole injection becomes stronger at high current density, holes can still be conducted to the light-emitting layer through different carrier conduction channels, thereby ensuring the hole concentration at high current density and improving the luminescence efficiency of the device.

[0022] (4) Because the structural characteristics of the organic compound of the present invention are conducive to improving the glass transition temperature of the molecule, it is also conducive to reducing the evaporation temperature of the molecule. That is to say, even if the molecular weight of the structure is relatively high, it can ensure a lower evaporation temperature. This excellent performance is not only conducive to the thermal evaporation of the material, but also controls the thermal decomposition rate of the material, thereby improving the stability of the material in device applications.

[0023] Moreover, for the molecular structure of aromatic amine characterized by the present invention, in addition to the connection mode between aromatic amine group and bridging group, the optimization of ligand connected to aromatic amine is beneficial to further improve the performance of the material. The selection of phenyl, naphthyl, dibenzofuranyl, phenanthrene and other groups is more beneficial to improve the stability and mobility of the material, and is also beneficial to the precise control of the HOMO energy level of the material, thereby obtaining a good device application effect of the material.

[0024] The organic functional materials constituting the OLED device include not only hole injection conductive materials but also electron injection conductive materials and light-emitting layer materials. Good device application effects require good carrier balance as a guarantee. Therefore, in order to obtain the best device application effects, the aromatic amine compounds matching the characteristic structure of the present invention also require specific electronic materials for matching. Based on the in-depth research of the inventors, the electronic material is preferably a material containing azabenzene structural characteristics, such as triazine materials, pyridine materials, pyrazine materials, etc. or compounds containing these characteristic groups. The aromatic amine compounds of the present invention are combined with azabenzene ring electron transport materials to make it easy for electrons and holes to obtain the best balance state, and have high efficiency and excellent lifespan. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a cross-sectional view of the organic electroluminescent device of the present invention.

[0026] In the figure, 1 represents the substrate layer; 2 represents the anode layer; 3 represents the hole injection layer; 4 represents the hole transport layer; 5 represents the luminescence auxiliary layer; 6 represents the luminescence layer; 7 represents the hole blocking layer; 8 represents the electron transport layer; 9 represents the electron injection layer; 10 represents the cathode layer; and 11 represents the covering layer.

[0027] Figure 2 This is the H NMR spectrum of compound 3;

[0028] Figure 3 This is the H NMR spectrum of compound 17. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] In the present invention, unless otherwise specified, HOMO means the highest occupied orbital of a molecule, and LUMO means the lowest unoccupied orbital of a molecule. In addition, in the present invention, HOMO and LUMO energy levels are expressed in absolute values, and the comparison between energy levels is also a comparison of the magnitude of their absolute values. Those skilled in the art know that the greater the absolute value of an energy level, the lower the energy of the energy level.

[0032] In the present invention, when a layer or element is referred to as being "on" another layer or substrate, the layer or element may be directly on the other layer or substrate, or there may be intervening layers. In addition, it will be understood that when a layer is referred to as being "between" two layers, the layer may be the only layer between the two layers, or there may be one or more intervening layers. The same reference numerals throughout the text represent the same elements.

[0033] In the present invention, when describing electrodes and organic electroluminescent devices, as well as other structures, the words "upper", "lower", "top" and "bottom" used to indicate orientation only indicate the orientation in a certain state, and do not mean that the related structure can only exist in the orientation described; on the contrary, if the structure can change its position, such as inverted, the orientation of the structure will be changed accordingly. Specifically, in the present invention, the "bottom" or "lower" side of the electrode refers to the side of the electrode close to the substrate during the preparation process, and the opposite side away from the substrate is the "top" or "upper" side.

[0034] In this specification, the term "substituted" means that one or more hydrogen atoms on a designated atom or group are replaced by a designated group, provided that the normal valency of the designated atom is not exceeded under the existing circumstances.

[0035] In this specification, the hole characteristic refers to a characteristic that can donate electrons when an electric field is applied and holes formed in the anode are easily injected into the light-emitting layer and transported in the light-emitting layer due to the conductive characteristic according to the highest occupied molecular orbital (HOMO) level.

[0036] In this specification, the electronic characteristics refer to the characteristics that electrons formed in the cathode can be easily injected into the light-emitting layer and transported in the light-emitting layer due to the conductive characteristics according to the lowest unoccupied molecular orbital (LUMO) level when an electric field is applied.

[0037] Compound represented by general formula (1)

[0038]

[0039] In the general formula (1), Ar 1 ,Ar 2Each independently represents a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, a substituted or unsubstituted terphenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted phenanthrenyl, a substituted or unsubstituted indenyl, or a substituted or unsubstituted piperonyl;

[0040] The m and n are represented as 1, 2 or 3;

[0041] The R 1 represents phenyl, naphthyl, dibenzofuranyl, benzofuranyl or furanyl;

[0042] The R 2 It is represented by the structure shown in general formula (2) or general formula (3), and general formula (2) and general formula (3) are connected to the a and b, b and c, or c and d sites of general formula (1) through the * site in a ring;

[0043]

[0044] L 1 , L 2 Each independently represents a direct bond, a phenylene group, a naphthylene group or a biphenylene group;

[0045] In the general formula (3), X represents an oxygen atom or N(R);

[0046] The R represents phenyl, naphthyl or biphenyl;

[0047] The substituent of the "substituted or unsubstituted" group is selected from one or more of a deuterium atom, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a naphthyl group, a biphenyl group, a benzofuranyl group, a dibenzofuranyl group, and a furanyl group.

[0048] In a preferred embodiment, the structure of the compound is as shown in general formula (1-1) to general formula (1-9):

[0049]

[0050] In the general formula (1-1) to the general formula (1-9), Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, a substituted or unsubstituted terphenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted phenanthrenyl, a substituted or unsubstituted indenyl, or a substituted or unsubstituted piperonyl;

[0051] The m and n are represented as 1, 2 or 3;

[0052] The R 1 represents phenyl, naphthyl, dibenzofuranyl, benzofuranyl or furanyl;

[0053] The R 2 It is represented by the structure shown in general formula (2) or general formula (3), and general formula (2) and general formula (3) are connected to the a and b, b and c, or c and d sites of general formula (1) through the * site in a ring;

[0054]

[0055]

[0056] L 1 , L 2 Each independently represents a direct bond, a phenylene group, a naphthylene group or a biphenylene group;

[0057] In the general formula (3), X represents an oxygen atom or N(R);

[0058] The R represents phenyl, naphthyl or biphenyl;

[0059] The substituent of the "substituted or unsubstituted" group is selected from one or more of a deuterium atom, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a naphthyl group, a biphenyl group, a benzofuranyl group, and a dibenzofuranyl group.

[0060] In a preferred embodiment, the structure of the compound is shown in general formula (4):

[0061]

[0062] In the general formula (4), Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, a substituted or unsubstituted terphenyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted phenanthrenyl, a substituted or unsubstituted indenyl, or a substituted or unsubstituted piperonyl;

[0063] The R 1 represents phenyl, naphthyl, dibenzofuranyl, benzofuranyl or furanyl;

[0064] The R 2 It is represented by the structure shown in general formula (2) or general formula (3), and general formula (2) and general formula (3) are connected to the a and b, b and c, or c and d sites of general formula (1) through the * site in a ring;

[0065]

[0066] L 1 , L 2 Each independently represents a direct bond, a phenylene group, a naphthylene group or a biphenylene group;

[0067] In the general formula (3), X represents an oxygen atom or N(R);

[0068] The R represents phenyl, naphthyl or biphenyl;

[0069] The substituent of the "substituted or unsubstituted" group is selected from one or more of a deuterium atom, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a naphthyl group, a biphenyl group, a benzofuranyl group, a dibenzofuranyl group, and a furanyl group.

[0070] Preferably, the R 1 Represents phenyl; the R 2 It is represented by the structure shown in general formula (2); Ar 1 ,Ar 2 At least one of them is selected from dibenzofuranyl.

[0071] Preferably, the R 1 Represents naphthyl; said R 2 It is represented by the structure shown in general formula (2); Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, or a substituted or unsubstituted dibenzofuranyl group.

[0072] Preferably, the R 1 Represents phenyl or naphthyl; the R 2 It is represented by the structure shown in general formula (3); the Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group.

[0073] Preferably, the R 1 Represents dibenzofuranyl; said R 2 It is represented by the structure shown in general formula (3) or general formula (2); Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group.

[0074] Preferably, the R 1 Represents a furanyl group; the R 2 It is represented by the structure shown in general formula (3); the Ar 1 ,Ar 2 Each independently represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group.

[0075] In a preferred embodiment, the specific structure of the compound is any one of the following structures:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] Organic electroluminescent devices

[0086] The present invention provides an organic electroluminescent device using an aromatic amine compound of general formula (1).

[0087] In an exemplary embodiment of the present invention, the organic electroluminescent device may include an anode, a hole transport region, a light emitting region, an electron transport region and a cathode, wherein the hole transport region comprises the aromatic amine compound of formula (1).

[0088] In a preferred embodiment, the hole transport region comprises a hole injection layer, a hole transport layer and a light-emitting layer auxiliary layer, and the light-emitting layer auxiliary layer comprises an aromatic amine compound of the general formula (1).

[0089] In a preferred embodiment, the electron transport region comprises a nitrogen heterocyclic compound represented by the general formula (4):

[0090]

[0091] Among them, Ar 5 ,Ar 6 ,Ar 7 are independently selected from substituted or unsubstituted C 6 -C 30 Aryl, substituted or unsubstituted C 5 -C 30 One of the heterocyclic groups;

[0092] L 3 Represents a single bond, substituted or unsubstituted C6 -C 30 Arylene, substituted or unsubstituted C containing one or more heteroatoms 5 -C 30 A heterocyclylene group;

[0093] X 1 , X 2 , X 3 independently represent N or CH, X 1 , X 2 , X 3 At least one of represents N;

[0094] The heteroatoms are each independently selected from N, O or S;

[0095] The substituent for substituting the "substituted or unsubstituted" group is one or more of a deuterium atom, a phenyl group, a naphthyl group, a biphenyl group, a dibenzofuranyl group, a dibenzothienyl group, a pyridyl group or a pyrimidyl group.

[0096] The organic electroluminescent device of the present invention may be a bottom-emitting organic electroluminescent device, a top-emitting organic electroluminescent device, or a stacked organic electroluminescent device, without any particular limitation.

[0097] In the organic electroluminescent device of the present invention, any substrate commonly used in organic electroluminescent devices can also be used. Examples thereof are transparent substrates, such as glass or transparent plastic substrates; opaque substrates, such as silicon substrates; flexible polyimide (PI) film substrates. Different substrates have different mechanical strengths, thermal stability, transparency, surface smoothness, and waterproofness. Depending on the properties of the substrate, its use direction is different. In the present invention, a transparent substrate is preferably used. The thickness of the substrate is not particularly limited.

[0098] anode

[0099] Preferably, an anode can be formed on a substrate. In the present invention, the anode and the cathode are opposite to each other. The anode can be made of a conductor with a higher work function to facilitate hole injection, and can be, for example, a metal such as nickel, platinum, copper, zinc, silver or an alloy thereof; a metal oxide such as zinc oxide, indium oxide, indium tin oxide (ITO) and indium zinc oxide (IZO); a combination of a metal and a metal oxide such as ZnO and Al or ITO and Ag; a conductive polymer such as poly(3-methylthiophene), poly(3,4-(ethylene-1,2-dioxy)thiophene) and polyaniline, but not limited thereto. The thickness of the anode depends on the material used, and is typically 50-500nm, preferably 70-300nm, and more preferably 100-200nm. In the present invention, a combination of a metal and a metal oxide, ITO and Ag, is preferably used.

[0100] cathode

[0101] The cathode can be made of a conductor with a lower work function to facilitate electron injection, such as a metal or its alloy, such as magnesium, calcium, sodium, potassium, titanium, indium, aluminum, silver, tin, and combinations thereof; a multilayer structure material, such as LiF / Al, Li 2 O / Al and BaF 2 / Ca, but not limited thereto. The thickness of the cathode depends on the material used, and is generally 10-50 nm, preferably 15-20 nm.

[0102] Emitting Area

[0103] In the present invention, the light-emitting region may be arranged between the anode and the cathode, and may include at least one host material and at least one guest material. As the host material and the guest material of the light-emitting region of the organic electroluminescent device of the present invention, the light-emitting layer materials for organic electroluminescent devices known in the prior art may be used. The host material may be, for example, a thiazole derivative, a benzimidazole derivative, a polydialkylfluorene derivative or 4,4'-bis(9-carbazolyl)biphenyl (CBP). The host material may use a compound containing an anthracene group. The guest material may be, for example, quinacridone, coumarin, rubrene, perylene and its derivatives, benzopyran derivatives, rhodamine derivatives or aminostyrene derivatives.

[0104] In a preferred embodiment of the present invention, the light emitting region comprises one or two host material compounds.

[0105] In a preferred embodiment of the present invention, the light-emitting region comprises two host material compounds, and the two host material compounds can form an exciplex.

[0106] In a preferred embodiment of the present invention, the host material of the light-emitting region is selected from one or more of the following compounds BH-1 to BH-11:

[0107]

[0108] In the present invention, the light-emitting region may contain a phosphorescent or fluorescent guest material to improve the fluorescent or phosphorescent properties of the organic electroluminescent device. Specific examples of phosphorescent guest materials include metal complexes of iridium, platinum, etc. For fluorescent guest materials, those commonly used in the art can be used. In a preferred embodiment of the present invention, the guest material of the light-emitting film layer used is selected from one of the following compounds BD-1 to BD-10:

[0109]

[0110] In the light emitting region of the present invention, the ratio of the host material to the guest material used is 99:1-70:30, preferably 99:1-85:15 and more preferably 97:3-87:13, based on mass.

[0111] The thickness of the light emitting region may be 10-50 nm, preferably 15-30 nm, but the thickness is not limited to this range.

[0112] Hole transport region

[0113] In the organic electroluminescent device of the present invention, the hole transport region is arranged between the anode and the light emitting region, and includes a hole injection layer, a hole transport layer and a light emitting auxiliary layer.

[0114] Hole injection layer

[0115] The hole injection material used in the hole injection layer (also called the anode interface buffer layer) is a material that can fully accept holes from the anode at a low voltage, and the highest occupied molecular orbital (HOMO) of the hole injection material is preferably a value between the work function of the anode material and the HOMO of the adjacent organic material layer. In a preferred embodiment of the present invention, the hole injection layer is a mixed film layer of a main organic material and a P-type doping material. In order to smoothly inject holes from the anode into the organic film layer, the HOMO energy level of the main organic material must have certain characteristics with the P-type doping material, so that it is expected to realize the occurrence of charge transfer states between the main material and the doping material, and realize the ohmic contact between the hole injection layer and the anode, thereby realizing efficient injection of holes from the electrode to the hole injection layer. This feature is summarized as: the difference between the HOMO energy level of the main material and the LUMO energy level of the P-type doping material is ≤0.4eV. Therefore, for hole-type main materials with different HOMO energy levels, different P-type doping materials need to be selected to match them in order to achieve ohmic contact at the interface and improve the hole injection effect.

[0116] Preferably, specific examples of the host organic material include: metal porphyrin, oligothiophene, aromatic amine organic material, hexanitrile hexaazatriphenylene, quinacridone organic material, perylene organic material, anthraquinone, polyaniline and polythiophene conductive polymers; but are not limited thereto. Preferably, the host organic material is an aromatic amine organic material.

[0117] Preferably, the P-type doping material is a compound having charge conductivity selected from the following: quinone derivatives or metal oxides, such as tungsten oxide and molybdenum oxide, but not limited thereto.

[0118] In a preferred embodiment of the present invention, the P-type doping material used is selected from any one of the following compounds P-1 to P-8:

[0119]

[0120]

[0121] In one embodiment of the present invention, the ratio of the host organic material to the P-type doping material used is 99:1-95:5, preferably 99:1-97:3, based on mass.

[0122] In a preferred embodiment of the present invention, the hole injection layer is a mixed film layer of an aromatic amine compound and a P-type doping material, and the aromatic amine compound is an aromatic amine compound of the general formula (1).

[0123] The thickness of the hole injection layer of the present invention may be 5-20 nm, preferably 8-15 nm, but the thickness is not limited to this range.

[0124] Hole transport layer

[0125] In the organic electroluminescent device of the present invention, a hole transport layer may be disposed above the hole injection layer. The hole transport material is a suitable material with high hole mobility, which can accept holes from the anode or the hole injection layer and transfer the holes to the light-emitting layer. Specific examples thereof include: aromatic amine organic materials, conductive polymers, block copolymers having both conjugated and non-conjugated parts, etc., but are not limited thereto. In a preferred embodiment, the hole transport layer comprises the same aromatic amine organic compound as the hole injection layer.

[0126] The thickness of the hole transport layer of the present invention may be 80, 100 or 200 nm, preferably 100-150 nm, but the thickness is not limited to this range.

[0127] Light-emitting auxiliary layer

[0128] In the organic electroluminescent device of the present invention, the luminescence auxiliary layer may be arranged between the hole transport layer and the luminescent layer, and in particular contact the luminescent layer. The luminescence auxiliary layer is arranged to contact the luminescent layer, and therefore, the hole transfer at the interface between the luminescent layer and the hole transport layer can be accurately controlled. In one embodiment of the present invention, the luminescence auxiliary layer material is selected from the aromatic amine compounds described in the general formula (1). The thickness of the luminescence auxiliary layer may be 5-20nm, preferably 8-15nm, but the thickness is not limited to this range.

[0129] Electron transport region

[0130] In the organic electroluminescent device of the present invention, the electron transport region is disposed between the light emitting region and the cathode, and includes a hole blocking layer, an electron transport layer and an electron injection layer, but is not limited thereto.

[0131] Electron injection layer

[0132] The electron injection layer may be disposed between the electron transport layer and the cathode. The electron injection layer material is generally preferably a material having a low work function so that electrons are easily injected into the organic functional material layer. Preferably, the electron injection layer material is an N-type metal material. As the electron injection layer material of the organic electroluminescent device of the present invention, the electron injection layer material for organic electroluminescent devices known in the prior art can be used, for example, lithium; lithium salts, such as 8-hydroxyquinoline lithium, lithium fluoride, lithium carbonate or lithium azide; or cesium salts, cesium fluoride, cesium carbonate or cesium azide. The thickness of the electron injection layer of the present invention can be 0.1-5nm, preferably 0.5-3nm and more preferably 0.8-1.5nm, but the thickness is not limited to this range.

[0133] Electron transport layer

[0134] The electron transport layer may be disposed on the light-emitting film layer or (if present) the hole blocking layer. The electron transport layer material is a material that easily receives electrons from the cathode and transfers the received electrons to the light-emitting layer. Preferably, the material has a high electron mobility. As the electron transport layer of the organic electroluminescent device of the present invention, the electron transport layer material known in the prior art for organic electroluminescent devices can be used, for example, Alq 3 , metal complexes of hydroxyquinoline derivatives represented by BAlq and LiQ, various rare earth metal complexes, triazole derivatives, triazine derivatives such as 2,4-bis(9,9-dimethyl-9H-fluorene-2-yl)-6-(naphthalene-2-yl)-1,3,5-triazine (CAS No.: 1459162-51-6), imidazole derivatives such as 2-(4-(9,10-di(naphthalene-2-yl)anthracene-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole (CAS No.: 561064-11-7, commonly known as LG201), oxadiazole derivatives, etc.

[0135] In a preferred organic electroluminescent device of the present invention, the electron transport layer comprises a nitrogen heterocyclic compound of the general formula (4):

[0136]

[0137] Among them, Ar 5 ,Ar 6 ,Ar 7 independently represent substituted or unsubstituted C 6 -C 30 Aryl, substituted or unsubstituted C 5 -C 30 One of the heterocyclic groups;

[0138] L 3 Represents a single bond, substituted or unsubstituted C 6 -C30 Arylene, substituted or unsubstituted C containing one or more heteroatoms 5 -C 30 A heterocyclylene group;

[0139] X 1 , X 2 , X 3 independently represent N or CH, X 1 , X 2 , X 3 At least one group in represents N;

[0140] The heteroatoms are each independently selected from N, O or S;

[0141] The substituents used for the substituent group are one or more of a deuterium atom, a phenyl group, a naphthyl group, a biphenyl group, a dibenzofuranyl group, a dibenzothienyl group, a pyridyl group, and a pyrimidyl group.

[0142] Preferably, the Ar 5 ,Ar 6 ,Ar 7 Each of the following is independently selected from the group consisting of substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted dibenzothiophene, and substituted or unsubstituted quinolyl;

[0143] The L 3 represented by a single bond, phenylene, biphenylene or naphthylene;

[0144] The substituents used for the substituent group are one or two of a deuterium atom, a phenyl group, a naphthyl group, a biphenyl group, a dibenzofuranyl group, a dibenzothienyl group, a pyridyl group, and a pyrimidyl group.

[0145] In a preferred embodiment of the present invention, the electron transport layer comprises any one of the following compounds:

[0146]

[0147]

[0148] In a more preferred embodiment of the present invention, the electron transport layer comprises any one of the compounds selected from the following:

[0149]

[0150] In a preferred embodiment of the present invention, in addition to the compound of formula (4), the electron transport layer also includes other compounds conventionally used in electron transport layers, for example, Alq3, LiQ, preferably LiQ. In a more preferred embodiment of the present invention, the electron transport layer is composed of one of the compounds of formula (4) and one of the other compounds conventionally used in electron transport layers (preferably LiQ).

[0151] The hole injection and transport rates of the hole transport region containing the aromatic amine compound of the present invention can be well matched with the electron injection and transport rates. Preferably, the hole injection and transport rates of the hole transport region containing the aromatic amine compound of the present invention can be better matched with the electron injection and transport rates of the electron transport region containing the nitrogen heterocyclic derivative of general formula (4).

[0152] Therefore, in a particular embodiment of the present invention, an electron transport region containing one or more nitrogen heterocyclic derivatives of the general formula (4) or composed thereof is used in combination with a hole transport region containing the aromatic amine compound of the present invention to achieve relatively better technical effects.

[0153] The thickness of the electron transport layer of the present invention may be 10-80 nm, preferably 20-60 nm, and more preferably 25-45 nm, but the thickness is not limited to this range.

[0154] Covering

[0155] In order to improve the light extraction efficiency of the organic electroluminescent device, a light extraction layer (i.e., CPL layer, also called covering layer) may be added to the cathode of the device. According to the principles of optical absorption and refraction, the refractive index of the CPL covering layer material should be as high as possible, and the absorption coefficient should be as small as possible. Any material known in the art can be used as the CPL layer material, such as Alq3, or N4,N4'-diphenyl-N4,N4'-di(9-phenyl-3-carbazolyl)biphenyl-4,4'-diamine. The thickness of the CPL covering layer is generally 5-300 nm, preferably 20-100 nm and more preferably 40-80 nm.

[0156] The organic electroluminescent device of the present invention may further include an encapsulation structure. The encapsulation structure may be a protective structure that prevents foreign substances such as moisture and oxygen from entering the organic layer of the organic electroluminescent device. The encapsulation structure may be, for example, a can, such as a glass can or a metal can; or a thin film covering the entire surface of the organic layer.

[0157] Hereinafter, an organic electroluminescent device according to an embodiment of the present invention is described.

[0158] In the accompanying drawings, the thickness of layers, films, substrates, regions, etc., is exaggerated for clarity. Throughout the specification, the same reference numerals represent the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "located" "on" another element, it can be directly located on the other element or there can also be intervening elements. In contrast, when an element is referred to as being "directly located" "on" another element, there are no intervening elements.

[0159] Figure 1 is a schematic cross-sectional view of an organic electroluminescent device according to an embodiment of the present invention.

[0160] See also Figure 1 According to an embodiment of the present invention, the organic electroluminescent device comprises an anode 2 and a cathode 10 facing each other, a hole transport region, a light-emitting layer 6 and an electron transport region sequentially arranged between the anode 2 and the cathode 10, and a substrate 1 under the anode 2 and a covering layer 11 arranged on the cathode, wherein the hole transport region comprises a hole injection layer 3, a hole transport layer 4 and an electron blocking layer 5, and the electron transport region comprises a hole blocking layer 7, an electron transport layer 8 and an electron injection layer 9.

[0161] The present invention also relates to a method for preparing an organic electroluminescent device, which comprises laminating an anode, a hole injection layer, a hole transport layer, an electron blocking layer, an organic film layer, an electron transport layer, an electron injection layer and a cathode successively on a substrate, and optionally a covering layer. In this regard, vacuum deposition, vacuum evaporation, spin coating, casting, LB method, inkjet printing, laser printing or LITI methods can be used, but are not limited thereto. In the present invention, it is preferred to use a vacuum evaporation method to form the various layers. Those skilled in the art can conventionally select various process conditions in the vacuum evaporation method according to actual needs.

[0162] In addition, it should be noted that the materials used to form each layer described in the present invention can be formed into a film alone and used as a single layer, or can be mixed with other materials to form a film and used as a single layer. It can also be a stacked structure between layers formed into films alone, a stacked structure between layers formed into films after mixing, or a stacked structure of layers formed into films alone and layers formed into films after mixing.

[0163] Preparation Example

[0164] Example 1: Synthesis of Compound 1

[0165]

[0166] Under nitrogen atmosphere, 0.06 mol of raw material B-1 was added to a 500 ml three-necked flask, and a mixed solvent (300 ml toluene, 90 ml H 2O) was dissolved, stirred for 1 hour under nitrogen, and then 0.05 mol of raw material A-1 and 0.1 mol of K were slowly added. 2 CO 3 、0.005molPd(PPh 3 ) 4 , heated to 90°C, reacted for 8 hours, and observed the reaction by thin layer chromatography (TLC) until the reaction was complete. After naturally cooling to room temperature, water was added to the reaction system for extraction, and the liquid was separated. The organic phase was subjected to reduced pressure rotary evaporation until there was no fraction. The obtained substance was purified by silica gel column to obtain intermediate P-1 with a purity of 99.37% and a yield of 89.2%. Elemental analysis structure (molecular formula C 12 H 8 BrCl): theoretical value: C, 53.87; H, 3.01; Br, 29.87; Cl, ​​13.25; test value: C, 53.80; H, 3.03; Br, 29.89; Cl, ​​13.28. LC-MS: measured value: 266.87 ([M+H] + ); exact mass: 265.95.

[0167] In a three-necked flask, under nitrogen protection, add 0.01 mol of intermediate P-1, 0.012 mol of raw material C-1, and 150 ml of toluene, stir and mix, then add 5×10 -5 molPd 2 (dba) 3 , 5×10 -5 mol tri-tert-butylphosphine, 0.03 mol sodium tert-butoxide, heated to 105°C, refluxed for 20 hours, sampled, no C-1 remained, reaction complete; cooled to room temperature, filtered, filtrate evaporated until no fraction, passed through neutral silica gel column, intermediate M-1 was obtained, purity 99.14%, yield 83.12%. Elemental analysis structure (molecular formula C 28 H 18 ClN): theoretical value: C, 83.26; H, 4.49; N, 3.47; Cl, ​​8.78; test value: C, 83.20; H, 4.51; N, 3.50; Cl, ​​8.80. LC-MS: measured value: 404.25 ([M+H] + ); exact mass: 403.11.

[0168] In a three-necked flask, under nitrogen protection, add 0.01 mol of raw material D-1, 0.012 mol of intermediate M-1, and 150 ml of toluene, stir and mix, and then add 5×10 -5 molPd 2 (dba) 3 , 5×10 -5mol tri-tert-butylphosphine, 0.03mol sodium tert-butoxide, heated to 105°C, refluxed for 24 hours, sampled, no intermediate M-1 remained, the reaction was complete; cooled to room temperature naturally, filtered, the filtrate was evaporated until there was no fraction, passed through a neutral silica gel column, and the target compound was obtained with a purity of 98.91% and a yield of 79.91%. Elemental analysis structure (molecular formula C 52 H 36 N 2 ): Theoretical value: C, 90.67; H, 5.27; N, 4.07; Test value: C, 90.74; H, 5.23; N, 4.05. LC-MS: Measured value: 689.37 ([M+H] + ); exact mass: 688.29.

[0169] The following compounds were prepared in the same manner as in Example 1, and the synthetic raw materials are shown in Table 1 below;

[0170] Table 1

[0171]

[0172]

[0173]

[0174] Detection Methods

[0175] Glass transition temperature Tg: measured by differential scanning calorimetry (DSC, DSC204F1 differential scanning calorimeter from NETZSCH, Germany), with a heating rate of 10°C / min.

[0176] HOMO energy level: tested by ionization energy test system (IPS3) in a vacuum environment.

[0177] Eg energy level: tested by double-beam UV-visible spectrophotometer (model: TU-1901), based on the UV spectrophotometry (UV absorption) baseline of the material single film and the rising side of the first absorption peak, the tangent is drawn and the value of the intersection of the tangent and the baseline is calculated.

[0178] Hole mobility: The material is made into a single-charge device and measured using the space charge limited current method (SCLC).

[0179] Triplet energy level T1: tested by Horiba's Fluorolog-3 series fluorescence spectrometer, the material test conditions are 2×10 -5 mol / L toluene solution.

[0180] The specific physical property test results are shown in Table 2.

[0181] Table 2

[0182]

[0183] It can be seen from the data in Table 2 above that the compounds of the present invention have suitable HOMO energy levels, higher hole mobility and wider band gap (Eg), and can realize organic electroluminescent devices with high efficiency and long life.

[0184] Preparation of organic electroluminescent devices

[0185] The molecular structures of the materials involved in the following preparation process are shown below:

[0186]

[0187] Device Comparison Example 1

[0188] The organic electroluminescent device was prepared by following the steps below:

[0189] like Figure 1 As shown, the substrate layer 1 washes the anode layer 2 (Ag (100nm)), that is, alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing are performed in sequence to remove organic residues on the surface of the anode layer. On the anode layer 2 after the above washing, a vacuum evaporation device is used to evaporate HT1 and P-1 with a film thickness of 10nm as the hole injection layer 3, and the mass ratio of HT-1 and P-1 is 97:3. Then evaporate HT-1 with a thickness of 117nm as the hole transport layer 4. Then evaporate EB-1 with a thickness of 10nm as the light-emitting auxiliary layer 5. After the evaporation of the above-mentioned light-emitting auxiliary layer material is completed, the light-emitting layer 6 of the OLED light-emitting device is prepared, and its structure includes BH-1 used as the main material of the OLED light-emitting layer 6, BD-1 as the doping material, the doping ratio of the doping material is 3% by weight, and the thickness of the light-emitting layer is 20nm. After the above-mentioned light-emitting layer 6, HB1 is continuously evaporated, and the evaporation film thickness is 8nm, as a hole blocking layer 7. On the hole blocking layer 7, ET-1 and Liq were continuously evaporated, the mass ratio of ET-1 and Liq was 1:1, and the vacuum evaporated film thickness of the material was 30nm, which was the electron transport layer 8. On the electron transport layer 8, a LiF layer with a film thickness of 1nm was made by a vacuum evaporation device, which was the electron injection layer 9. On the electron injection layer 9, a Mg:Ag electrode layer with a film thickness of 16nm was made by a vacuum evaporation device, and the mass ratio of Mg and Ag was 1:9, which was used as the cathode layer 10. On the cathode layer 10, 70nm of CP-1 was vacuum evaporated as the covering layer 11.

[0190] Device Comparison Examples 2-5

[0191] The method of device comparative example 1 is followed, except that the organic materials in the hole injection layer and the hole transport layer are replaced with organic materials shown in Table 3, respectively.

[0192] Device Examples 1-23

[0193] The method of device comparative example 1 is followed, except that the organic materials in the hole injection layer, the hole transport layer or the electron transport layer are replaced with organic materials shown in Table 3, respectively.

[0194] Table 3

[0195]

[0196] In the above table, taking Example 1 as an example, the "P-1:HT1=3:9710nm" in the second column means that the materials used for the hole injection layer are compound HT1 and P-type doping material P-1, 3:97 means that the weight ratio of P-type doping material P-1 to compound HT1 is 3:97, and 10nm means the thickness of the layer; the "110nm" in the fourth column means that the material used is compound 1, and the thickness of the layer is 10nm. The meanings in other tables can be deduced by analogy.

[0197] After the OLED light-emitting device is prepared as described above, the cathode and the anode are connected using a known driving circuit, and various properties of the device are measured.

[0198] The device performance measurement results of Examples 1-23 and Comparative Examples 1-5 are shown in Table 4.

[0199] Table 4

[0200]

[0201] Note: LT95 refers to the brightness of 50mA / cm 2 Under the condition of , the time taken for the device brightness to decay to 95% of the original brightness;

[0202] The voltage, current efficiency and color coordinates were tested using an IVL (current-voltage-luminance) test system (Suzhou Fushida Scientific Instrument Co., Ltd.); the current density was 10 mA / cm 2 ;

[0203] The life test system is the EAS-62C OLED life test system produced by Japan System Research Co., Ltd.

[0204] It can be seen from the results of Comparative Examples 1-5 and Device Examples 1-23 in Table 4 that the use of the aromatic amine compounds of the present invention as the light-emitting auxiliary layer material effectively improves the device efficiency and life due to its higher carrier transfer rate and exciton blocking ability. In particular, the efficiency of the device is unexpectedly significantly improved (while maintaining a certain life advantage).

Claims

1. An aromatic amine compound, characterized in that: The structure of the compound is shown in general formula (1): In the general formula (1), Ar1 and Ar2 are independently substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted phenanthryl; The m and n are represented as 1, 2 or 3; The R1 is phenyl, naphthyl, or dibenzofuranyl; The R2 is represented by the structure shown in the general formula (2), and the general formula (2) is connected to the a and b, b and c, or c and d sites of the general formula (1) through the * site; L1 and L2 shown in the figure are independently represented by a direct bond, a phenylene group, a naphthylene group or a biphenylene group; The substituent of the "substituted or unsubstituted" group is selected from one or more of a deuterium atom, a phenyl group, a naphthyl group, a biphenyl group, a benzofuranyl group, a furanyl group, and a dibenzofuranyl group; The following compounds are excluded from the general formula (1):

2. The aromatic amine compound according to claim 1, characterized in that The structures of the compounds are shown in general formula (1-1) to general formula (1-3): In general formula (1-1) to general formula (1-3), Ar1, Ar2, m, n, R1, L1, and L2 have the same definitions as in claim 1.

3. The aromatic amine compound according to claim 1, characterized in that The R1 is a phenyl group; the R2 is a structure represented by the general formula (2); and at least one of Ar1 and Ar2 is selected from dibenzofuranyl.

4. The aromatic amine compound according to claim 1, characterized in that The R1 represents a naphthyl group; the R2 represents a structure represented by the general formula (2); the Ar1 and Ar2 represent independently a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, or a substituted or unsubstituted dibenzofuranyl group.

5. The aromatic amine compound according to claim 1, characterized in that The R1 represents a dibenzofuranyl group; the R2 represents a structure represented by the general formula (2); the Ar1 and Ar2 independently represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted diphenyl group, or a substituted or unsubstituted terphenyl group.

6. An aromatic amine compound, characterized in that: The specific structure of the compound is any one of the following structures:

7. An organic electroluminescent device, which comprises an anode, a hole transport region, a light emitting region, an electron transport region and a cathode in sequence, characterized in that: The hole transport region comprises the aromatic amine compound according to any one of claims 1 to 6.

8. The organic electroluminescent device according to claim 7, characterized in that: The hole transport region includes a hole injection layer, a hole transport layer and a light-emitting layer auxiliary layer, and the light-emitting layer auxiliary layer includes the aromatic amine compound according to any one of claims 1 to 6.

9. The organic electroluminescent device according to claim 7, characterized in that: The electron transport region comprises a nitrogen heterocyclic compound represented by the general formula (4): wherein Ar5, Ar6, and Ar7 are independently selected from substituted or unsubstituted C6-C 30 Aryl, substituted or unsubstituted C5-C 30 One of the heterocyclic groups; L3 represents a single bond, a substituted or unsubstituted C6-C 30 Arylene, substituted or unsubstituted C5-C 30 A heterocyclylene group; X1, X2, and X3 independently represent N or CH, and at least one of X1, X2, and X3 represents N; The heteroatoms are each independently selected from N, O or S; The substituent for substituting the "substituted or unsubstituted" group is one or more of a deuterium atom, a phenyl group, a naphthyl group, a biphenyl group, a dibenzofuranyl group, a dibenzothienyl group, a pyridyl group or a pyrimidyl group.

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