Organic electroluminescent devices and nitrogen-containing compounds for use in organic electroluminescent devices

Abstract

An organic electroluminescent device exhibiting high light emission efficiency and a nitrogen-containing compound for use in the organic electroluminescent device are provided. The organic electroluminescent device includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region. The emission layer may include a nitrogen-containing compound represented by Formula 1. [Formula 1]

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2020-0017920, filed with the Korean Intellectual Property Office on February 13, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to organic electroluminescent devices and nitrogen-containing compounds for use in organic electroluminescent devices. Background Technology

[0004] Currently, there is active development on organic electroluminescent displays as image display devices. Unlike liquid crystal displays, organic electroluminescent displays are so-called self-emissive display devices, in which holes and electrons injected from the first and second electrodes recombine in the emitting layer, thus the emitting layer contains luminescent materials of organic compounds that emit light to achieve display.

[0005] When applying organic electroluminescent devices to display devices, there is a continuous demand for organic electroluminescent devices with low driving voltage, high light emission efficiency, and long lifespan. There is also a continuous demand for the development of materials for organic electroluminescent devices that can reliably achieve these characteristics.

[0006] In recent years, in order to realize efficient organic electroluminescent devices, technology has continued to develop, which is related to phosphorescence emission utilizing triplet energy or delayed fluorescence utilizing triplet-triplet annihilation (TTA) (where singlet excitons are generated through collisions of triplet excitons), and is related to thermally activated delayed fluorescence (TADF) materials that utilize the delayed fluorescence phenomenon. Summary of the Invention

[0007] This disclosure provides an organic electroluminescent device with long service life and high efficiency, and a nitrogen-containing compound used therein.

[0008] This disclosure also provides an organic electroluminescent device comprising a thermally activated delayed fluorescence emitting material and a nitrogen-containing compound used as the thermally activated delayed fluorescence emitting material.

[0009] Embodiments of the present invention provide an organic electroluminescent device, which may include a first electrode; a hole transport region disposed on the first electrode; an emission layer disposed on the hole transport region; an electron transport region disposed on the emission layer; and a second electrode disposed on the electron transport region. The first electrode and the second electrode may each include at least one material selected from the group consisting of: Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, In, Sn, Zn, their oxides, their compounds, and mixtures thereof. The emission layer may include a nitrogen-containing compound represented by Formula 1:

[0010] [Formula 1]

[0011]

[0012] In Formula 1, X1 can be NAr1Ar2, OAr3, or SAr4, Ar1 to Ar4 can each be independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring, R1 to R4 can each be independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring, and a and b can each be independently an integer selected from 0 to 3.

[0013] In one implementation, the emitting layer may emit delayed fluorescence.

[0014] In an embodiment, the emission layer may be a delayed fluorescence emission layer containing a first compound and a second compound, and the first compound may include a nitrogen-containing compound.

[0015] In one embodiment, the emitting layer may be a thermally activated delayed fluorescence emitting layer that emits blue light.

[0016] Embodiments of the present invention provide nitrogen-containing compounds represented by Formula 1.

[0017] In the implementation method, equation 1 can be represented by equation 2:

[0018] [Equation 2]

[0019]

[0020] In Formula 2, X2 may be NAr1, O, or S, R5 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted boron group, a substituted or unsubstituted thio group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring, c may be an integer selected from 0 to 4, and Ar1, R1 to R3, a, and b may be the same as those defined in Formula 1.

[0021] In the implementation method, equation 2 can be represented by equation 3:

[0022] [Formula 3]

[0023]

[0024] In Formula 3, Ar5 may be a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, c may be an integer selected from 0 to 3, and R1 to R3, R5, a and b may be the same as those defined in Formula 2.

[0025] In the implementation, equation 2 can be represented by equation 4-1 or equation 4-2:

[0026] [Equation 4-1]

[0027]

[0028] [Equation 4-2]

[0029]

[0030] In Formulas 4-1 and 4-2, R6 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring, c' may be an integer selected from 0 to 3, d may be an integer selected from 0 to 5, d' may be an integer selected from 0 to 4, and R1 to R3, R5 and a to c may be the same as those defined in Formula 2.

[0031] In the implementation, equation 2 can be represented by equation 5-1 or equation 5-2:

[0032] [Equation 5-1]

[0033]

[0034] [Equation 5-2]

[0035]

[0036] In Equations 5-1 and 5-2, R1 to R3, R5, and a to c can be the same as those defined in Equation 2.

[0037] In the implementation method, equation 2 can be represented by equation 6:

[0038] [Formula 6]

[0039]

[0040] In Formula 6 above, X3 can be NAr1, O, or S; Ar6 can be a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring; R7 can be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring; c” can be an integer selected from 0 to 2; e can be an integer selected from 0 to 4; and X2, Ar1, R1 to R3, R5, and a and b can be the same as those defined in Formula 2.

[0041] In the implementation method, equation 6 can be represented by equation 7:

[0042] [Formula 7]

[0043]

[0044] In Formula 7, R8 and R9 may each be independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring, e' and f may each be independently an integer selected from 0 to 3, and X2, X3, R1 to R3, R5, R7, a and b, and c” may be the same as those defined in Formula 6.

[0045] In the implementation, X2 and X3 can be the same.

[0046] In an embodiment, R3 may be a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted biphenyl group.

[0047] In the embodiments, R1 and R2 above can each independently be a hydrogen atom, a deuterium atom, a substituted or unsubstituted arylamine group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted carbazole group.

[0048] In an embodiment, the nitrogen-containing compound represented by Formula 1 may be selected from one of the compounds in group 1. Attached Figure Description

[0049] The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the inventive concept and, together with the description, serve to explain the principles of the inventive concept. In the drawings:

[0050] Figure 1 A schematic cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention;

[0051] Figure 2 A schematic cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention;

[0052] Figure 3 A schematic cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention; and

[0053] Figure 4 A schematic cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. Detailed Implementation

[0054] The inventive concept can be modified in various ways and can be embodied in different forms, and embodiments will be explained in detail with reference to the accompanying drawings. However, the inventive concept can be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, all modifications, equivalents, and substitutions that fall within the spirit and scope of the inventive concept should be included in the inventive concept.

[0055] In this description, it should be understood that when an element or layer is referred to as being "on" another element or layer, "connected to" or "attached to" another element or layer, it may be directly on the other element or layer, directly connected to or directly attached to the other element or layer, or there may be an intermediate element or layer.

[0056] The same reference numerals refer to the same elements throughout the drawings. In order to effectively describe the technical content, the thickness, scale, and dimensions of the elements may be enlarged in the drawings.

[0057] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated items. For example, “A and / or B” can be understood to mean “A, B, or A and B”. The terms “and” and “or” can be used to connect or separate meanings and can be understood as equivalent to “and / or”. Throughout this disclosure, the expression “at least one of A, B, and C” can indicate only A, only B, only C, both A and B, both A and C, both B and C, all A, B, and C, or variations thereof.

[0058] For the purposes of its meaning and interpretation, the term "at least one..." is intended to include the meaning of "at least one selected from the group consisting of...". For example, "at least one of A and B" can be understood to mean "A, B, or A and B". When preceding a list of components, the term "at least one..." modifies the entire list of components, not any individual component in the list.

[0059] It should be understood that although the terms "first," "second," etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of exemplary embodiments of the inventive concept, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Singular terms may include plural forms unless the context clearly indicates otherwise.

[0060] For example, terms such as "below," "under," "above," and "over" are used to describe the relationships between the configurations shown in the accompanying drawings. These terms are used as relative concepts and are described with reference to the directions indicated in the accompanying drawings.

[0061] Given the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system), the term “about” or “approximately” as used herein includes a specified value and means within an acceptable range of deviation from a particular value as determined by one of ordinary skill in the art. For example, “about” may mean within one or more standard deviations, or within ±20%, ±10%, or ±5% of the specified value.

[0062] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept pertains. It should also be understood that terms defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field, and are expressly defined herein unless they are interpreted in an ideal or overly formal sense.

[0063] It should be understood that the terms “comprises,” “comprising,” “includes,” “including,” “have,” “having,” “contains,” and / or “containing” are intended to specify the presence of the stated features, integers, steps, operations, elements, components, or combinations thereof in this disclosure, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

[0064] In the following description, an organic electroluminescent device according to an embodiment of the present invention and compounds of the embodiments therein will be described with reference to the accompanying drawings.

[0065] Figures 1 to 4 A schematic cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. See also... Figures 1 to 4 In each of the organic electroluminescent devices 10 according to the embodiments, the first electrode EL1 and the second electrode EL2 are arranged to face each other, and the emitting layer EML may be disposed between the first electrode EL1 and the second electrode EL2.

[0066] In addition to the emitter layer EML, each of the organic electroluminescent devices 10 in the embodiments may further include a functional layer between the first electrode EL1 and the second electrode EL2. This functional layer may include a hole transport region HTR and an electron transport region ETR. Each of the organic electroluminescent devices 10 according to the embodiments may be stacked sequentially, including the first electrode EL1, the hole transport region HTR, the emitter layer EML, the electron transport region ETR, and the second electrode EL2. The organic electroluminescent device 10 in the embodiments may include a capping layer CPL disposed on the second electrode EL2.

[0067] The organic electroluminescent device 10 of the embodiment may include the nitrogen-containing compound of the embodiment (described later) in the emitter layer EML disposed between the first electrode EL1 and the second electrode EL2. However, the embodiment is not limited to this, and the organic electroluminescent device 10 of the embodiment may include the compound according to the embodiment not only in the emitter layer EML, but also in the hole transport region HTR or electron transport region ETR (which may be included in the functional layer disposed between the first electrode EL1 and the second electrode EL2), or in the capping layer CPL disposed on the second electrode EL2.

[0068] and Figure 1 Compare, Figure 2A schematic cross-sectional view of the organic electroluminescent device 10 according to an embodiment is provided, wherein the hole transport region HTR includes a hole injection layer HIL and a hole transport layer HTL, and the electron transport region ETR includes an electron injection layer EIL and an electron transport layer ETL. Figure 1 Compare, Figure 3 A schematic cross-sectional view of the organic electroluminescent device 10 according to an embodiment is provided, wherein the hole transport region HTR includes a hole injection layer HIL, a hole transport layer HTL, and an electron blocking layer EBL, and the electron transport region ETR includes an electron injection layer EIL, an electron transport layer ETL, and a hole blocking layer HBL. Figure 2 Compare, Figure 4 A schematic cross-sectional view of an organic electroluminescent device 10 according to an embodiment is shown, which includes a capping layer CPL disposed on a second electrode EL2.

[0069] The first electrode EL1 is conductive. The first electrode EL1 may be formed of a metal alloy or a conductive compound. The first electrode EL1 may be a pixel electrode or a positive electrode. The first electrode EL1 may be a transmissive electrode, a transmissive-reflective electrode, or a reflective electrode. When the first electrode EL1 is a transmissive electrode, it may include a transparent metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium tin zinc oxide (ITZO). When the first electrode EL1 is a transmissive-reflective electrode or a reflective electrode, it may include at least one material selected from the group consisting of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, In, Sn, Zn, their oxides, their compounds, and mixtures thereof (e.g., a mixture of Ag and Mg). The first electrode EL1 may have a multilayer structure, including a reflective layer or a transmissive-reflective layer formed of the above materials and a transparent conductive layer formed of ITO, IZO, ZnO, ITZO, etc. For example, the first electrode EL1 may have a three-layer structure of ITO / Ag / ITO, but is not limited to this. The thickness of the first electrode EL1 can be approximately... to approximately Within a certain range. For example, the thickness of the first electrode EL1 can be approximately... to approximately Within the range.

[0070] The hole transport region HTR is provided on the first electrode EL1. The hole transport region HTR may include at least one of the following: hole injection layer HIL, hole transport layer HTL, hole buffer layer (not shown), and electron blocking layer EBL.

[0071] The hole transport region (HTR) can have a single layer formed of a single material, a single layer formed of different materials, or a multilayer structure including multiple layers formed of different materials.

[0072] For example, the hole transport region HTR may have a single-layer structure of a hole injection layer HIL or a hole transport layer HTL, and may have a single-layer structure formed of a hole injection material and a hole transport material. The hole transport region HTR may have a single-layer structure formed of different materials, or a structure in which hole injection layer HIL / hole transport layer HTL, hole injection layer HIL / hole transport layer HTL / hole buffer layer (not shown), hole injection layer HIL / hole buffer layer (not shown), hole transport layer HTL / hole buffer layer, or hole injection layer HIL / hole transport layer HTL / electron blocking layer EBL are stacked sequentially from the first electrode EL1, but the implementation is not limited to this.

[0073] Hole transport regions (HTRs) can be formed using various methods, such as vacuum deposition, spin coating, casting, Langmuir-Brookett (LB) method, inkjet printing, laser printing, and laser-induced thermal imaging (LITI).

[0074] Hole injection layer HIL may include, for example, phthalocyanine compounds (such as copper phthalocyanine), N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine (DNTPD), 4,4′,4"-[tris(3-methylphenyl)phenylamino]triphenylamine (m-MTDATA), 4,4′,4"-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4′,4"-tris{N-(2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / dodecylbenzenesulfonic acid (PANI / DBSA), polyaniline / camphor sulfonic acid (PANI / CSA), polyaniline / poly(4-styrene sulfonate) (PANI / PSS), N,N′-di(naphthyl-1-yl)-N,N′-diphenyl-benzidine (NPB), 2,2'-dimethyl-N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (α-NPD), triphenylamine-containing polyether ketone (TPAPEK), 4-isopropyl-4′-methyldiphenyliodonium [tetra(pentafluorophenyl)borate], dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexaonitrile (HAT-CN), etc.

[0075] Hole transport layer (HTL) may include materials generally known in the art. For example, HTL may further include carbazole derivatives (such as N-phenylcarbazole and polyvinylcarbazole), fluorine derivatives, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), triphenylamine derivatives (such as 4,4',4”-tris(N-carbazolyl)triphenylamine (TCTA)), N,N'-di(naphthyl-1-yl)-N,N'-diphenyl-benzidine (N PB), 2,2'-dimethyl-N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine (α-NPD), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC), 4,4'-bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl (HMTPD), 1,3-bis(N-carbazolyl)benzene (mCP), etc.

[0076] Electron blocking layers (EBLs) may include, for example, carbazole derivatives (such as N-phenylcarbazole and polyvinylcarbazole), fluorine derivatives, N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), triphenylamine derivatives (such as 4,4',4”-tris(N-carbazolyl)triphenylamine (TCTA)), N,N'-bis(naphthyl-1-yl)-N,N'-diphenyl α-NPD, 2,2'-dimethyl-N,N'-di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC), 4,4'-bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl (HMTPD), mCP, etc.

[0077] The thickness of the hole transport region (HTR) can be approximately to approximately Within a certain range. For example, the thickness of the hole transport region (HTR) can be approximately... to approximately Within a certain range. The thickness of the hole injection layer (HIL) can, for example, be approximately... to approximately Within a certain range, and the thickness of the hole transport layer (HTL) can be approximately... to approximately Within a certain range. For example, the thickness of the electron blocking layer (EBL) can be approximately... to approximately Within the specified range, if the thicknesses of the hole transport region (HTR), hole injection layer (HIL), hole transport layer (HTL), and electron blocking layer (EBL) satisfy the above range, satisfactory hole transport properties can be achieved without a significant increase in driving voltage.

[0078] In addition to the materials described above, the hole transport region (HTR) may further include a charge-generating material to increase conductivity. The charge-generating material may be uniformly or non-uniformly dispersed in the hole transport region (HTR). The charge-generating material may be, for example, a p-doper. The p-doper may be at least one of quinone derivatives, metal oxides, and cyano-containing compounds, but is not limited thereto. For example, non-limiting examples of p-dopers may include quinone derivatives (such as tetracyanoquinone dimethyl (TCNQ) and 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone dimethyl (F4-TCNQ)), metal oxides (such as tungsten oxide and molybdenum oxide), etc., but are not limited thereto.

[0079] As described above, in addition to the hole injection layer HIL and the hole transport layer HTL, the hole transport region HTR may further include at least one of a hole buffer layer (not shown) and an electron blocking layer EBL. The hole buffer layer (not shown) can compensate for the resonant distance according to the wavelength of light emitted from the emitter layer EML and can increase the light emission efficiency. Materials that may be included in the hole transport region HTR can be used as materials that may be included in the hole buffer layer (not shown). The electron blocking layer EBL is a layer that can be used to prevent electrons from being injected from the electron transport region ETR into the hole transport region HTR.

[0080] The emitter layer EML can be provided on the hole transport region (HTR). The thickness of the emitter layer EML can be approximately... to approximately Within a certain range. For example, the thickness of the emitter layer EML can be approximately... to approximately Within the range. The emitter layer (EML) can have a single layer formed of a single material, a single layer formed of different materials, or a multilayer structure with multiple layers formed of different materials.

[0081] The emitting layer (EML) can emit one of the following colors of light: red, green, blue, white, yellow, and cyan. The EML may include fluorescent or phosphorescent emitting materials.

[0082] In an embodiment, the emitting layer EML may be a fluorescent emitting layer. For example, some light emitted from the emitting layer EML may come from thermally activated delayed fluorescence (TADF). The emitting layer EML may include a light-emitting component that emits thermally activated delayed fluorescence, and in an embodiment, the emitting layer EML may be an emitting layer that emits thermally activated delayed fluorescence (emitting blue light).

[0083] The emitting layer EML of the organic electroluminescent device 10 of the embodiment may include a nitrogen-containing compound according to an embodiment of the present invention.

[0084] In this description, the term "substituted or unsubstituted" may indicate that at least one substituent selected from the group consisting of: deuterium, halogen, cyano, nitro, amino, silyl, oxy, thio, sulfinyl, sulfonyl, carbonyl, boron, phosphonyl oxide, phosphonyl sulfide, alkyl, alkenyl, cycloalkyl, aryl, and heterocyclic. Each of the above substituents may be substituted or unsubstituted. For example, biphenyl may be interpreted as aryl, or a phenyl group substituted with a phenyl group.

[0085] In this description, the term "bonded to an adjacent group to form a ring" may indicate a ring bonded to an adjacent group to form a substituted or unsubstituted hydrocarbon ring, or a substituted or unsubstituted heterocycle. Hydrocarbon rings include aliphatic hydrocarbon rings and aromatic hydrocarbon rings. Heterocycles include aliphatic heterocycles and aromatic heterocycles. Rings formed by bonding to adjacent groups may be monocyclic or polycyclic. Rings formed by bonding to each other may connect to another ring to form a spirostructure.

[0086] In this description, the term "adjacent group" may mean a substituent that replaces an atom directly bonded to the atom substituted by the corresponding substituent, another substituent that replaces the atom substituted by the corresponding substituent, or a substituent spatially located at the position closest to the corresponding substituent. For example, the two methyl groups in 1,2-dimethylbenzene may be interpreted as "adjacent groups" to each other, and the two ethyl groups in 1,1-diethylcyclopentane may be interpreted as "adjacent groups" to each other.

[0087] In this description, examples of halogen atoms may include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0088] In this description, unless otherwise specified, alkyl groups may be chain-like or cyclic. The number of carbons in an alkyl group may be 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Examples of alkyl groups may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, tert-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl, 2- Octyldecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldodecyl, 2-octyldodecyl, n-tridecyl, n-tetradecyl, n-pentadecanyl, n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl, 2-octylhexadecyl, n-heptadecyl, n-octadecyl, n-heptadecyl, n-eicosyl, 2-ethyleicosyl, 2-butyleicosyl, 2-hexyleicosyl, 2-octyleicosyl, n-monodecyl, n-eicos ... etc. Examples of cyclic alkyl groups may include, but are not limited to, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-tert-butylcyclohexyl, cyclooctyl, etc.

[0089] In this description, alkenyl means a hydrocarbon group comprising at least one carbon-carbon double bond in the middle or at the end of an alkyl group having two or more carbon atoms. Alkenyl groups can be straight-chain or branched. While there is no specific limitation on the number of carbon atoms, it is 2 to 30, 2 to 20, or 2 to 10. Examples of alkenyl groups include, but are not limited to, vinyl, 1-butenyl, 1-pentenyl, 1,3-butadienyl, styryl, styrylvinyl, etc.

[0090] In this description, alkynyl means a hydrocarbon group comprising at least one carbon-carbon triple bond in the middle or at the end of an alkyl group having two or more carbon atoms. The alkynyl group can be straight-chain or branched. While there is no specific limitation on the number of carbon atoms, it is 2 to 30, 2 to 20, or 2 to 10. Specific examples of alkynyl groups may include, but are not limited to, ethynyl, propynyl, etc.

[0091] In this description, the cycloalkyl group can be any functional group or substituent derived from an aliphatic hydrocarbon ring, or any functional group or substituent derived from an aromatic hydrocarbon ring. The number of cyclic carbon atoms in the cycloalkyl group can be 5 to 60, 5 to 30, or 5 to 20.

[0092] In this description, aryl means any functional group or substituent derived from an aromatic hydrocarbon ring. Aryl can be monocyclic or polycyclic. The number of cyclic carbon atoms in an aryl group can be 6 to 30, 6 to 20, or 6 to 15. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, fluorenyl, anthraceneyl, phenanthryl, biphenyl, terphenyl, tetraphenyl, pentaphenyl, hexaphenyl, triphenylene, pyrene, benzofluoranthracene, 1,2-benzophenanthryl, etc.

[0093] In this description, heterocyclic group means any functional group or substituent derived from a ring containing at least one of B, O, N, P, Si, and S as a heteroatom. Heterocyclic groups include aliphatic heterocyclic groups and aromatic heterocyclic groups. Aromatic heterocyclic groups may be heteroaryl. Aliphatic and aromatic heterocycles may be monocyclic or polycyclic.

[0094] In this description, the heterocyclic group may include at least one of B, O, N, P, Si, and S as a heteroatom. When the heterocyclic group contains two or more heteroatoms, the two or more heteroatoms may be the same or different from each other. The heterocyclic group may be a monocyclic or polycyclic heterocyclic group, and may include heteroaryl groups. The number of cyclic carbon atoms in the heterocyclic group may be 2 to 30, 2 to 20, or 2 to 10.

[0095] In this description, the aliphatic heterocyclic group may include at least one of B, O, N, P, Si, and S as a heteroatom. The number of cyclic carbon atoms in the aliphatic heterocyclic group may be 2 to 30, 2 to 20, or 2 to 10. Examples of aliphatic heterocyclic groups include ethylene oxide, cyclothioethylene, pyrrolidinyl, piperidinyl, tetrahydrofuranyl, tetrahydrothiophenyl, thiaalkyl, tetrahydropyranyl, 1,4-dioxane, etc., but are not limited thereto.

[0096] In this description, a heteroaryl group may include at least one of B, O, N, P, Si, and S as a heteroatom. When a heteroaryl group contains two or more heteroatoms, the two or more heteroatoms may be the same or different from each other. The heteroaryl group may be a monocyclic heteroaryl or a polycyclic heteroaryl. The number of cyclic carbon atoms in the heteroaryl group may be 2 to 30, 2 to 20, or 2 to 10. Examples of heteroaryl groups may include, but are not limited to, thienyl, furanyl, pyrrolyl, imidazolyl, thiazolyl, oxazolyl, oxadiazolyl, triazolyl, pyridyl, bipyridyl, pyrimidinyl, triazinyl, acridinel, pyridazinyl, quinolinyl, quinazolinyl, quinoxazinyl, phenothiazinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, isoquinolinyl, indolyl, carbazole, N-arylcarbazole, N-heteroarylcarbazole, N-alkylcarbazole, benzoxazolyl, benzimidazolyl, benzothiazolyl, benzocarbazole, benzothiophene, dibenzothiophene, thiophene-thiophene, benzofuranyl, phenanthrolyl, isoxazolyl, thiadiazolyl, phenothiazolyl, phenothiazinyl, dibenzothiophene, dibenzofuranyl, etc.

[0097] In this description, there is no specific limitation on the number of carbon atoms in the amino group, but it can be from 1 to 30. The amino group can include alkylamino, arylamino, or heteroarylamino. Examples of amino groups include, but are not limited to, methylamino, dimethylamino, phenylamino, diphenylamino, naphthylamino, 9-methyl-anthraylamino, etc.

[0098] In this description, the thio group may include alkylthio and arylthio.

[0099] In this description, boryl groups include alkoboryl and arylboryl groups. A boryl group can mean a boron atom bonded to an alkyl or aryl group as defined above. Examples of boryl groups may include, but are not limited to, dimethylboryl, diethylboryl, tert-butylmethylboryl, diphenylboryl, phenylboryl, etc.

[0100] In this description, the oxygen group can be an alkoxy or an aryloxy group. An oxygen group can mean an oxygen atom bonded to an alkyl or aryl group as defined above. Examples of oxygen groups include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, pentoxy, hexoxy, octoxy, nonoxy, decoxy, benzyloxy, etc.

[0101] The nitrogen-containing compound according to an embodiment of the present invention is represented by Formula 1:

[0102] [Formula 1]

[0103]

[0104] In Equation 1, X1 can be NAr1Ar2, OAr3, or SAr4.

[0105] In Formula 1, Ar1 to Ar4 may each be independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring.

[0106] In Formula 1, R1 to R4 may each be independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring.

[0107] In Equation 1, a and b can each be an integer selected from 0 to 3 independently. When a is an integer of 2 or greater, multiple R1s can be the same or different from each other, and when b is an integer of 2 or greater, multiple R2s can be the same or different from each other.

[0108] In the embodiments, R4 in Formula 1 may be a substituted or unsubstituted phenyl group.

[0109] In the implementation, equation 1 can be represented by the following equation 2:

[0110] [Equation 2]

[0111]

[0112] In Equation 2, X2 can be NAr1, O, or S.

[0113] In Formula 2, R5 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted boron group, a substituted or unsubstituted thio group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or may be bonded to an adjacent group to form a ring.

[0114] In Equation 2, c can be an integer selected from 0 to 4. When c is an integer of 2 or greater, multiple R5s can be the same or different from each other.

[0115] In Equation 2, Ar1, R1 to R3, as well as a and b, can be the same as those defined in Equation 1.

[0116] In the implementation method, equation 2 can be represented by equation 3:

[0117] [Formula 3]

[0118]

[0119] In Formula 3, Ar5 can be a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms.

[0120] In Equation 3, c can be an integer selected from 0 to 3, and R1 to R3, R5, a and b can be the same as those defined in Equation 2.

[0121] In the implementation method, equation 2 can be represented by equation 4-1:

[0122] [Equation 4-1]

[0123]

[0124] In Formula 4-1, R6 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or may be bonded to an adjacent group to form a ring.

[0125] In Equation 4-1, d can be an integer selected from 0 to 5, and when d is an integer of 2 or greater, multiple R6s can be the same or different from each other.

[0126] In Equation 4-1, R1 to R3, R5, and a to c can be the same as those defined in Equation 2.

[0127] In the implementation, equation 2 can be represented by equation 4-2:

[0128] [Equation 4-2]

[0129]

[0130] In Formula 4-2, R6 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or may be bonded to an adjacent group to form a ring.

[0131] In Equation 4-2, d' can be an integer selected from 0 to 4, and when d' is an integer of 2 or greater, multiple R6s can be the same or different from each other.

[0132] In Equation 4-2, c' can be an integer selected from 0 to 3, and when c' is an integer of 2 or greater, multiple R5s can be the same or different from each other.

[0133] In Equation 4-2, R1 to R3, R5, and a and b can be the same as those defined in Equation 2.

[0134] In the implementation, equation 2 can be represented by equation 5-1 or equation 5-2:

[0135] [Equation 5-1]

[0136]

[0137] [Equation 5-2]

[0138]

[0139] In Equations 5-1 and 5-2, R1 to R3, R5, and a to c can be the same as those defined in Equation 2.

[0140] In the implementation method, equation 2 can be represented by equation 6:

[0141] [Formula 6]

[0142]

[0143] In Equation 6, X3 can be NAr1, O, or S, and

[0144] In Formula 6, Ar6 can be a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring.

[0145] In Formula 6, R7 may be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or may be bonded to an adjacent group to form a ring.

[0146] In Equation 6, c” can be an integer selected from 0 to 2, and when c” is 2, multiple R5s can be the same or different from each other.

[0147] In Equation 6, e can be an integer selected from 0 to 4, and when e is an integer of 2 or greater, multiple R7s can be the same or different from each other.

[0148] In Equation 6, X2, Ar1, R1 to R3, R5, and a and b can be the same as those defined in Equation 2.

[0149] In the implementation method, equation 6 can be represented by equation 7:

[0150] [Formula 7]

[0151]

[0152] In Formula 7, R8 and R9 may each be independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring.

[0153] In Equation 7, e' and f can each be an integer selected from 0 to 3 independently. When e' is an integer of 2 or greater, multiple R7s can be the same or different from each other, and when f is an integer of 2 or greater, multiple R8s can be the same or different from each other.

[0154] In Equation 7, X2, X3, R1 to R3, R5, R7, a and b, and c” can be the same as those defined in Equation 6.

[0155] In the implementation, X2 and X3 in Equations 6 and 7 can be the same.

[0156] In the embodiments, R3 in Formulas 1 to 7 may be a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted biphenyl group.

[0157] In the embodiments, R1 and R2 in Formulas 1 to 7 may each be independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted arylamine group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted carbazole group.

[0158] In embodiments, the nitrogen-containing compound represented by Formula 1 may be one of the compounds selected from group 1, which includes compounds 1 to 179. However, the inventive concept is not limited thereto.

[0159] [Compound Group 1]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173] The aforementioned nitrogen-containing compounds can be used in the organic electroluminescent device 10 of the embodiments to improve the light emission efficiency and lifespan of the organic electroluminescent device. The aforementioned nitrogen-containing compounds can also be used in the emission layer (EML) of the organic electroluminescent device 10 of the embodiments to improve the light emission efficiency and lifespan of the organic electroluminescent device.

[0174] In this embodiment, the emission layer EML may be a delayed fluorescence emission layer comprising a first compound and a second compound, and the nitrogen-containing compound of the embodiment represented by Formula 1 may be included in the first compound of the emission layer EML. For example, the first compound may be a dopant, and the second compound may be the host compound.

[0175] In this embodiment, the host material may be a host material for emitting delayed fluorescence, and the dopant may be a dopant material for emitting delayed fluorescence. The nitrogen-containing compound of the embodiment represented by Formula 1 may be included as a dopant material in the emission layer EML. For example, the nitrogen-containing compound of the embodiment represented by Formula 1 may be used as a TADF dopant.

[0176] Although not shown in the accompanying drawings, the organic electroluminescent device 10 of the embodiment may include a plurality of emission layers EML. The emission layers EML may be stacked sequentially. For example, the organic electroluminescent device 10 including a plurality of emission layers EML may emit white light. The organic electroluminescent device 10 including a plurality of emission layers EML may be an organic electroluminescent device having a series structure. When the organic electroluminescent device 10 includes a plurality of emission layers EML, at least one emission layer EML may include a nitrogen-containing compound as described above according to the present invention.

[0177] The emitter layer (EML) may further include dopants, and known materials can be used as dopants. For example, styrene derivatives (e.g., 1,4-bis[2-(3-N-ethylcarbazolyl)vinyl]benzene (BCzVB), 4-(di-p-tolylamino)-4'-[(di-p-tolylamino)styrene]stilbene (DPAVB), and N-(4-((E)-2-(6-((E)-4-(diphenylamino)styrene)naphth-2-yl)vinyl)phenyl)-N-phenylaniline (N-BDAVB) At least one of Bi, perylene and its derivatives (e.g., 2,5,8,11-tetra-tert-butylperylene (TBP)), pyrene and its derivatives (e.g., 1,1'-dipyrene, 1,4-dipyrenebenzene, 1,4-bis(N,N-diphenylamino)pyrene and 1,6-bis(N,N-diphenylamino)pyrene) and 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) can be used as a dopant, but is not limited thereto.

[0178] The emitter layer EML may further include commonly known materials in the art as the host material. For example, the emitter layer EML may include, but is not limited to, tris(8-hydroxyquinoline)aluminum (Alq3), bis[2-(diphenylphosphine)phenyl]ether oxide (DPEPO), 4,4'-bis(carbazole-9-yl)biphenyl (CBP), 1,3-bis(carbazole-9-yl)benzene (mCP), 2,8-bis(diphenylphospho)dibenzo[b,d]furan (PPF), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), poly(N-vinylcarbazole) (PVK), 9,10-bis(naphthyl-2-yl)anthracene (ADN), and 3-tert-butyl At least one of 9,10-bis(naphthyl-2-yl)anthracene (TBADN), stilbene aromatic hydrocarbon (DSA), 4,4'-bis(9-carbazolyl)-2,2'-dimethylbiphenyl (CDBP), 2-methyl-9,10-bis(naphthyl-2-yl)anthracene (MADN), hexaphenylcyclotriphosphazene (CP1), 1,4-bis(triphenylsilyl)benzene (UGH-2), hexaphenylcyclotrisiloxane (DPSiO3), octaphenylcyclotetrasiloxane (DPSiO4), and 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi).

[0179] When the emitting layer EML emits red light, the emitting layer EML may further include, for example, a fluorescent material comprising, for example, tris(dibenzoylmethyl)phenanthroline europium (PBD:Eu(DBM)3(Phen)) and / or perylene. When the emitting layer EML emits red light, the dopant included in the emitting layer EML may be, for example, at least one of the following: metal complexes (such as bis(1-phenylisoquinoline) iridium acetylacetonate (PIQIr(acac)), bis(1-phenylquinoline) iridium acetylacetonate (PQIr(acac)), tris(1-phenylquinoline) iridium (PQIr) and octaethylporphyrin platinum (PtOEP)), organometallic complexes, rubrene and its derivatives, and 4-dicyanomethylene-2-(p-dimethylaminostyryl)-6-methyl-4H-pyran (DCM) and its derivatives.

[0180] When the emitting layer EML emits green light, the emitting layer EML may further include, for example, a fluorescent material comprising, tris(8-hydroxyquinoline)aluminum (Alq3). When the emitting layer EML emits green light, the dopant included in the emitting layer EML may be, for example, selected from metal complexes (such as planar-tris(2-phenylpyridine)iridium (Ir(ppy)3)), organometallic complexes, and coumarins and their derivatives.

[0181] When the emitting layer EML emits blue light, the emitting layer EML may further include, for example, a fluorescent material selected from any of the following groups: spiro-DPVBi, spiro-6P, stilbene (DSB), stilbene aromatic (DSA), polyfluorene (PFO)-based polymers, and poly(p-phenylenevinylene) (PPV)-based polymers. When the emitting layer EML emits blue light, the dopant included in the emitting layer EML may, for example, be selected from metal complexes (such as (4,6-F₂ppy)₂Irpic), organometallic complexes, and perylene and its derivatives.

[0182] exist Figures 1 to 4 In the organic electroluminescent device 10 of the embodiments described herein, the electron transport region (ETR) is disposed on the emitter layer (EML). The electron transport region (ETR) may include at least one of the hole blocking layer (HBL), the electron transport layer (ETL), and the electron injection layer (EIL), but the embodiments are not limited thereto.

[0183] The electron transport region (ETR) can have a single layer formed of a single material, a single layer formed of different materials, or a multilayer structure including multiple layers formed of different materials.

[0184] For example, the electron transport region (ETR) may have a single-layer structure of an electron injection layer (EIL) or an electron transport layer (ETL), and may have a single-layer structure formed of an electron injection material and an electron transport material. The ETR may have a single-layer structure formed of different materials, or may have a structure in which electron transport layers (ETL) / electron injection layers (EIL), or hole blocking layers (HBL) / electron transport layers (ETL) / electron injection layers (EIL) are stacked sequentially from the emitter layer (EML), but is not limited thereto. to approximately Within the range.

[0185] Electron transport regions (ETRs) can be formed using various methods, such as vacuum deposition, spin coating, casting, Langmuir-Brookett (LB) method, inkjet printing, laser printing, and laser-induced thermal imaging (LITI).

[0186] When the electron transport region (ETR) includes an electron transport layer (ETL), the ETL may include anthracene compounds. However, the inventive concept is not limited thereto, and the ETL may include, for example, tris(8-hydroxyquinoline)aluminum (Alq3), 1,3,5-tris[(3-pyridyl)-benzene-3-yl]benzene, 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, bis[2-(diphenylphosphine)phenyl]ether oxide (DPEPO), 2-(4-(N-phenylbenzimidazol-1-yl)phenyl)-9,10-dinaphthylanthracene, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). ), 4,7-diphenyl-1,10-phenanthroline (Bphen), 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthyl-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), bis(2-methyl-8-hydroxyquinoline-N1,O8)-(1,1'-biphenyl-4-hydroxy)aluminum (BAlq), bis(benzoquinoline-10-hydroxy)beryllium (Bebq2), 9,10-bis(naphthyl-2-yl)anthracene (ADN), or mixtures thereof. The thickness of the electron transport layer (ETL) can be approximately to approximately Within a certain range. For example, the thickness of the electron transport layer (ETL) can be approximately... to approximately Within the specified range. If the thickness of the electron transport layer (ETL) meets the above range, satisfactory electron transport characteristics can be obtained without a significant increase in the driving voltage.

[0187] If the electron transport region (ETR) includes an electron injection layer (EIL), the EIL can be formed using metal halides (such as LiF, NaCl, CsF, RbCl, and RbI), lanthanides (such as Yb), metal oxides (such as Li₂O and BaO), or lithium 8-hydroxyquinoline (LiQ), but the invention is not limited thereto. The EIL can also be formed from a mixture of an electron injection material and an insulating organometallic salt. The insulating organometallic salt can be a material having a band gap of about 4 eV or higher. Specifically, the insulating organometallic salt can include, for example, metal acetates, metal benzoates, metal acetoacetates, metal acetylacetonates, or metal stearates. The thickness of the EIL can be approximately... to approximately Within a certain range. For example, the thickness of the electron-injected layer (EIL) can be approximately... to approximately Within the specified range. If the thickness of the electron injection layer (EIL) meets the above range, then satisfactory electron injection properties can be obtained without a significant increase in the driving voltage.

[0188] As described above, the electron transport region (ETR) may include a hole blocking layer (HBL). The hole blocking layer (HBL) may include, but is not limited to, at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), bis[2-(diphenylphosphine)phenyl] ether oxide (DPEPO), and 4,7-diphenyl-1,10-phenanthroline (Bphen).

[0189] The second electrode EL2 is provided on the electron transport region ETR. The second electrode EL2 can be a common electrode or a negative electrode. The second electrode EL2 can be a transmission electrode, a transmission-reflection electrode, or a reflection electrode. When the second electrode EL2 is a transmission electrode, the second electrode EL2 can be formed of a transparent metal oxide (e.g., ITO, IZO, ZnO, ITZO, etc.).

[0190] When the second electrode EL2 is a transmissive or reflective electrode, the second electrode EL2 may include at least one material selected from the group consisting of: Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, In, Sn, Zn, their oxides, their compounds, and mixtures thereof (e.g., a mixture of Ag and Mg). The second electrode EL2 may have a multilayer structure, including a reflective or transmissive layer formed of the above materials and a transparent conductive layer formed of ITO, IZO, ZnO, ITZO, etc.

[0191] Although not shown, the second electrode EL2 can be connected to the auxiliary electrode. When the second electrode EL2 is connected to the auxiliary electrode, the resistance of the second electrode EL2 can be reduced.

[0192] See Figure 4 The organic electroluminescent device 10 according to the embodiment may further include a capping layer CPL on the second electrode EL2. The capping layer CPL may include, for example, α-NPD, NPB, TPD, m-MTDATA, Alq3, CuPc, N4,N4,N4',N4'-tetra(biphenyl-4-yl)biphenyl-4,4'-diamine (TPD15), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), etc.

[0193] The organic electroluminescent device 10 according to an embodiment of the present invention may include a nitrogen-containing compound represented by Formula 1 as described above, thereby exhibiting excellent light emission efficiency and long lifespan characteristics. The organic electroluminescent device 10 of the embodiment can achieve high efficiency and long lifespan characteristics in the blue wavelength region.

[0194] The compounds and organic electroluminescent devices according to embodiments of the present invention will be described in detail below with reference to examples and comparative examples. The examples shown below are illustrated for the purpose of understanding the inventive concept only, and the scope of the inventive concept is not limited thereto.

[0195] [Example]

[0196] (Synthesis of nitrogen-containing compounds)

[0197] In the following description, the method for synthesizing nitrogen-containing compounds is an example, but the method for synthesizing nitrogen-containing compounds according to embodiments of the present invention is not limited to the examples below.

[0198] 1. Synthesize compound 5

[0199]

[0200] (Synthesize compound A)

[0201] 2-Phenylacetyl-1H-benzimidazole (15.1 g, 77.7 mmol) and 1-bromo-3,5-difluorobenzene (5.0 g, 25.9 mmol) were added to 1-methyl-2-pyrrolidone (NMP, 200 ml), and 60% NaH (5.18 g, 130 mmol) was added at room temperature under argon atmosphere. When hydrogen production ceased, the mixture was stirred at approximately 130 °C for about 8 hours. The mixture was allowed to stand to cool, and liquid separation was performed by adding water and toluene. The organic layer was concentrated, purified by column chromatography (silica gel), concentrated, filtered, and washed with hexane to obtain compound A (10.8 g, 77% yield).

[0202] (Synthesize compound B)

[0203] Compound A (10.0 g, 18 mmol), diphenylamine, bis(dibenzylacetone)palladium(0) (Pd(dba)2, 0.64 g, 1.1 mmol), tri-tert-butylphosphonium tetrafluoroborate (P(tBu)3HBF4, 0.27 g, 1.48 mmol), and sodium tert-butoxide (tBuONa, 5.33 g, 55 mmol) were added to toluene (120 mL) and stirred at approximately 90 °C for approximately 6 hours. The mixture was allowed to stand to cool and then separated into liquids by adding toluene and water. The organic layer was concentrated, purified by column chromatography (silica gel), concentrated, filtered, and washed with hexane to obtain compound B (9.30 g, 80% yield).

[0204] (Synthetic compound 5)

[0205] Compound B (8.00 g, 13 mmol) was added to 1,2-dichlorobenzene (ODCB, 127 ml), and BBr3 (12.7 g) was added. The mixture was stirred at approximately 150 °C for about 20 hours. After cooling, triethylamine (TEA, 38.6 g) and toluene were added to dissolve the compound. The resulting mixture was then subjected to liquid-liquid separation by adding water to concentrate the organic layer. The concentrated organic layer was purified by column chromatography (silica gel) to obtain compound 5 (6.30 g, 78% yield). Sublimation purification was performed (320 °C, 3.7 x 10⁻⁶). -3 Pa) and perform device evaluation. FAB-MS m / z = 637 (M + +1)

[0206] 2. Synthesis of compound 6

[0207]

[0208] (Synthesis of compound C)

[0209] As a reaction scheme, compound A (10.0 g, 18 mmol) and carbazole (6.67 g, 22 mmol) were reacted in the same manner as compound B to synthesize compound C (8.34 g, 72% yield).

[0210] (Synthetic compound 6)

[0211] As a reaction scheme, compound C (10.0 g, 15.9 mmol) was reacted in the same manner as compound 5 to synthesize compound 6 (3.54 g, 35% yield). Purification was performed by sublimation (320 °C, 3.0 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 635 (M ++1)

[0212] 3. Synthetic compound 44

[0213]

[0214] (Synthesize compound D)

[0215] As a reaction scheme, 2-phenyl-1H-benzimidazole (10.0 g, 51 mmol) and 1,3-dibromo-5-fluorobenzene (15.6 g, 62 mmol) were reacted in the same manner as compound A to synthesize compound D (14.3 g, 65% yield).

[0216] (Synthesis of compound E)

[0217] As a reaction scheme, compound D (14.0 g, 33 mmol) was reacted in the same manner as compound B to synthesize compound E (17.4 g, 88% yield).

[0218] (Synthetic compound 44)

[0219] As a reaction scheme, compound E (17.0 g, 28 mmol) was reacted in the same manner as compound 5 to synthesize compound 44 (5.5 g, 32% yield). Purification was performed by sublimation (330 °C, 5.0 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 613 (M + +1)

[0220] 4. Synthetic compound 80

[0221]

[0222] (Synthesis of compound F)

[0223] As a reaction, 2-phenyl-1H-benzis[d]imidazole (10.0 g, 51 mmol) was reacted in the same manner as compound A to synthesize compound F (16.8 g, 89% yield).

[0224] (Synthetic compound G)

[0225] As a reaction scheme, compound F (16.0 g, 44 mmol) and phenol were reacted in the same manner as compound A to synthesize compound G (14.4 g, 75% yield).

[0226] (Synthesis of compound H)

[0227] As a reaction scheme, compound G (14.0 g, 32 mmol) was reacted in the same manner as compound B to synthesize compound H (14.1 g, 84% yield).

[0228] (Synthetic compound 80)

[0229] As a reaction scheme, compound H (14.0 g, 26 mmol) was reacted in the same manner as compound 5 to synthesize compound 80 (3.1 g, 22% yield). Purification was performed by sublimation (270 °C, 4.5 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 537 (M + +1)

[0230] 5. Synthetic compound 92

[0231]

[0232] (Synthesis of compound I)

[0233] As a reaction scheme, compound F (10.0 g, 27 mmol) and 3-(diphenylamino)-phenol were reacted in the same manner as compound A to synthesize compound I (13.8 g, 83% yield).

[0234] (Synthetic compound J)

[0235] As a reaction scheme, compound I (13.2 g, 22 mmol) was reacted in the same manner as compound B to synthesize compound J (13.2 g, 87% yield).

[0236] (Synthetic compound 92)

[0237] As a reaction scheme, compound J (13.0 g, 19 mmol) was reacted in the same manner as compound 5 to synthesize compound 92 (2.0 g, 15% yield). Purification was performed by sublimation (330 °C, 3.2 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 704 (M + +1)

[0238] 6. Synthesis of compound 116

[0239]

[0240] (Synthesis of compound K)

[0241] As a reaction scheme, compound F (10.0 g, 27 mmol) and 3-(diphenylamino)-benzylthiophenol were reacted in the same manner as compound A to synthesize compound K (13.6 g, 80% yield).

[0242] (Synthetic compound L)

[0243] As a reaction scheme, compound K (13.0 g, 21 mmol) was reacted in the same manner as compound B to synthesize compound L (12.7 g, 86% yield).

[0244] (Synthetic compound 116)

[0245] As a reaction scheme, compound L (12.0 g, 17 mmol) was reacted in the same manner as compound 5 to synthesize compound 116 (2.80 g, 23% yield). Purification was performed by sublimation (340 °C, 3.8 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 720 (M + +1)

[0246] 7. Synthesize compound 125

[0247]

[0248] (Synthetic compound M)

[0249] Compound D (15.0 g, 35 mmol), tris(dibenzylacetone)dipalladium(0) (Pd2(dba)3, 0.81 g, 0.88 mmol), 2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl (Ruphos, 0.69 g, 1.48 mmol), and tBuONa (4.01 g, 42 mmol) were added to toluene (80 mL) and stirred at 60 °C for 24 hours. The mixture was allowed to stand to cool and then separated by adding toluene and water. The organic layer was concentrated, purified by column chromatography (silica gel), concentrated, filtered, and washed with hexane to obtain compound M (12.3 g, 68% yield).

[0250] (Synthetic compound N)

[0251] As a reaction scheme, compound M (12.0 g, 23 mmol) and aniline were reacted in the same manner as compound B to synthesize compound N (9.3 g, 76% yield).

[0252] (Synthetic compound O)

[0253] As a reaction scheme, compound N (9.0 g, 17 mmol) and 1,3-dibromobenzene were reacted in the same manner as compound B to synthesize compound O (6.7 g, 70% yield).

[0254] (Synthetic compound 125)

[0255] As a reaction scheme, compound O (6.5 g, 12 mmol) was reacted in the same manner as compound 5 to synthesize compound 125 (3.0 g, 21% yield). Purification was performed by sublimation (400 °C, 3.6 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 1146 (M + +1)

[0256] 8. Synthesize compound 126

[0257]

[0258] (Synthesis of compound P)

[0259] As a reaction, 2-phenyl-1H-benzis[d]imidazole (15.0 g, 77 mmol) and 1-fluoro-3-bromo-5-methoxybenzene were reacted in the same manner as compound A to synthesize compound P (19.0 g, 65% yield).

[0260] (Synthetic compound Q)

[0261] As a reaction scheme, compound P (18.0 g, 47 mmol) was reacted in the same manner as compound B to synthesize compound Q (20.4 g, 92% yield).

[0262] (Synthetic compound R)

[0263] Compound Q (20.0 g, 43 mmol) was added to dichloromethane (200 mL), and BBr3 (21.5 g, 86 mmol) was added dropwise at approximately 0 °C. The mixture was stirred at room temperature for approximately 48 hours. The reaction solution was poured into ice water and subjected to liquid-liquid separation. The organic layer was concentrated, purified by column chromatography (silica gel), concentrated, filtered, and washed with hexane to obtain compound R (15.7 g, 81% yield).

[0264] (Synthetic compound S)

[0265] As a reaction scheme, compound R (15.0 g, 33 mmol) and 1,3-difluorobenzene were reacted in the same manner as compound A to synthesize compound S (13.0 g, 80% yield).

[0266] (Synthetic compound 126)

[0267] As a reaction scheme, compound S (12.5 g, 13 mmol) was reacted in the same manner as compound 5 to synthesize compound 126 (2.5 g, 20% yield). Purification was performed by sublimation (370 °C, 7.7 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 996 (M + +1)

[0268] 9. Synthesize compound 152

[0269]

[0270] (Synthetic compound T)

[0271] As a reaction, 1,3-dibromo-5-methoxybenzene (12.0 g, 45 mmol) was reacted in the same manner as compound B to synthesize compound T (16.0 g, 80% yield).

[0272] (Synthetic compound U)

[0273] As a reaction scheme, compound T (15.0 g, 34 mmol) was reacted in the same manner as compound R to synthesize compound U (10.9 g, 75% yield).

[0274] (Synthetic compound V)

[0275] As a reaction scheme, compound U (10.0 g, 23 mmol) and 1-fluoro-3-iodobenzene were reacted in the same manner as compound A to synthesize compound V (10.6 g, 72% yield).

[0276] (Synthetic compound W)

[0277] Compound V (10.0 g, 16 mmol), compound R (9.34 g, 21 mmol), CuI (0.15 g, 0.79 mmol), K₂CO₃ (8.77 g, 63 mmol), and tris(2,4-pentanedione)ferric(III) (Fe(III)(acac)₃, 0.56 g, 1.6 mmol) were added to 1-methyl-2-pyrrolidone (NMP, 36 ml), and the mixture was heated and stirred at approximately 180 °C for approximately 24 hours. The mixture was allowed to stand to cool, and then the liquid was separated by adding toluene and water and filtering through diatomaceous earth. The organic layer was concentrated, purified by column chromatography (silica gel), concentrated, filtered, and washed with hexane to obtain compound W (9.55 g, 63% yield).

[0278] (Synthetic compound 152)

[0279] As a reaction scheme, compound W (9.0 g, 9.4 mmol) was reacted in the same manner as compound 5 to synthesize compound 152 (2.9 g, 32% yield). Purification was performed by sublimation (370 °C, 3.2 x 10⁻⁶ mmol / L). -3 Pa) and perform device evaluation. FAB-MS m / z = 971 (M + +1)

[0280] (Manufacturing organic electroluminescent devices)

[0281] The organic electroluminescent devices of Examples 1 to 9 were manufactured using the above-mentioned compounds as emission layer materials.

[0282] [Example Compounds]

[0283]

[0284] Organic electroluminescent devices of Comparative Examples 1 and 2 were fabricated using the following comparative example compounds X1 and X2 as emission layer materials.

[0285] [Comparative Compounds]

[0286]

[0287] The organic electroluminescent devices of the embodiments and comparative examples were manufactured by the following methods.

[0288] Will have about Thick ITO is patterned on a glass substrate, rinsed with ultrapure water, and subjected to UV ozone treatment for approximately 10 minutes to form the first electrode. Then, HAT-CN is deposited to approximately [amount missing]. The thickness of α-NPD is deposited to approximately [amount missing]. And deposit mCP to approximately The thickness is increased to form a hole transport region.

[0289] When forming the emission layer, the nitrogen-containing compound of the examples or the comparative example compound is co-deposited with mCBP (3,3'-bis(9H-carbazole-9-yl)biphenyl) at a ratio of about 1:99 to form A thick layer.

[0290] Formed on the emitter layer using TPBi Thick layers, formed with LiF A thick layer is used to form the electron transport region. A layer of approximately [missing information] is formed using aluminum (Al). The thickness of the second electrode.

[0291] In this embodiment, a vacuum deposition apparatus is used to form a hole transport region, an emitter layer, an electron transport region, and a second electrode.

[0292] (Evaluating the characteristics of organic electroluminescent devices)

[0293] To evaluate the characteristics of the organic electroluminescent devices according to the embodiments and comparative examples, the maximum emission wavelength (nm) and maximum external quantum yield (EQE) were measured using a luminance distribution characteristic measurement device C9920-11 from Hamamatsu Photonics, Inc. max (%) and at approximately 1000 nits (1000 cd / m 2 External quantum efficiency (EQE) at brightness 1000尼特 (%), and through EQE 1000尼特 (%) divided by EQE max (%) Calculate the roll-off.

[0294] [Table 1]

[0295]

[0296]

[0297] Referring to the results in Table 1, the maximum external quantum efficiency (EQE) is confirmed when the emitter layer includes a nitrogen-containing compound according to the embodiment. max ), at approximately 1000 nits (1000 cd / m³) 2 External quantum efficiency (EQE) at brightness 1000尼特 Both the roll-off value and the value of the comparison example showed improvement.

[0298] This is because the nitrogen-containing compound conceived according to the present invention possesses improved properties as an electron acceptor by including a structure in which benzimidazole (a heterocycle) is fused. The fusion of benzimidazole resolves the structural distortion of the compound, and the improved resonance effect increases molecular stability.

[0299] By using a nitrogen-containing compound represented by Formula 1 as the emission layer material, the organic electroluminescent device of the embodiment can achieve high light emission efficiency in the blue light wavelength region.

[0300] The organic electroluminescent device according to embodiments of the present invention can achieve high efficiency and long service life.

[0301] Nitrogen-containing compounds according to embodiments of the present invention can improve the efficiency and lifespan of organic electroluminescent devices.

[0302] Although the inventive concept has been described with reference to embodiments thereof, it should be understood that the inventive concept is not limited to these embodiments, but that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the inventive concept.

[0303] Therefore, the technical scope of the present invention is not intended to be limited to what is set forth in the detailed description of the specification, but is intended to be defined by the appended claims.

Claims

1. An organic electroluminescent device, comprising: First electrode; Hole transport region arranged on the first electrode; An emission layer disposed on the hole transport region; An electron transmission region arranged on the emission layer; and The second electrode is disposed on the electron transport region, wherein The first electrode and the second electrode each comprise at least one material selected from the group consisting of: Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, In, Sn, Zn, their oxides, their compounds, and mixtures thereof. The emission layer comprises a nitrogen-containing compound represented by Formula 1: [Formula 1] In Equation 1, X1 is NAr1Ar2, OAr3, or SAr4. Ar1 to Ar4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring. R1 to R4 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring. a and b are each an independent integer selected from 0 to 3.

2. The organic electroluminescent device of claim 1, wherein the emitting layer emits delayed fluorescence.

3. The organic electroluminescent device as claimed in claim 1, wherein... The emission layer is a delayed fluorescence emission layer comprising a first compound and a second compound, and The first compound includes the nitrogen-containing compound represented by Formula 1.

4. The organic electroluminescent device of claim 1, wherein the emitting layer is a thermally activated delayed fluorescence emitting layer that emits blue light.

5. The organic electroluminescent device as claimed in claim 1, wherein formula 1 is represented by formula 2: [Equation 2] In Equation 2, X2 is NAr1, O, or S. R5 is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted boron group, a substituted or unsubstituted thio group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or is bonded to an adjacent group to form a ring. c is an integer selected from 0 to 4, and Ar1, R1 to R3, and a and b are the same as those defined in Equation 1.

6. The organic electroluminescent device as claimed in claim 5, wherein formula 2 is represented by formula 3: [Formula 3] In Equation 3, Ar5 is a hydrogen atom, a deuterium atom, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, where c is an integer selected from 0 to 3. R1 to R3, R5, and a and b are the same as those defined in Equation 2.

7. The organic electroluminescent device as claimed in claim 5, wherein formula 2 is represented by formula 4-1 or formula 4-2: [Equation 4-1] [Equation 4-2] In equations 4-1 and 4-2, R6 is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or is bonded to an adjacent group to form a ring. c' is an integer selected from 0 to 3. d is an integer selected from 0 to 5. d' is an integer selected from 0 to 4, and R1 to R3, R5, and a to c are the same as those defined in Equation 2.

8. The organic electroluminescent device as claimed in claim 5, wherein formula 2 is represented by formula 5-1 or formula 5-2: [Equation 5-1] [Equation 5-2] In Equations 5-1 and 5-2, R1 to R3, R5, and a to c are the same as those defined in Equation 2.

9. The organic electroluminescent device as claimed in claim 5, wherein formula 2 is represented by formula 6: [Formula 6] In Equation 6, X3 is NAr1, O, or S. Ar6 is a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or is bonded to an adjacent group to form a ring. R7 is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or is bonded to an adjacent group to form a ring. c” is an integer selected from 0 to 2. e is an integer selected from 0 to 4, and X2, Ar1, R1 to R3, R5, and a and b are the same as those defined in Equation 2.

10. The organic electroluminescent device as claimed in claim 9, wherein formula 6 is represented by formula 7: [Formula 7] In Equation 7, R8 and R9 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring. e' and f are each an independent integer selected from 0 to 3, and X2, X3, R1 to R3, R5, R7, a, b and c” are the same as those defined in Equation 6.

11. The organic electroluminescent device of claim 9, wherein X2 and X3 are identical.

12. The organic electroluminescent device of claim 1, wherein R3 is a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted biphenyl group.

13. The organic electroluminescent device of claim 1, wherein R1 and R2 are each independently a hydrogen atom, a deuterium atom, a substituted or unsubstituted arylamine group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted carbazole group.

14. The organic electroluminescent device of claim 1, wherein the nitrogen-containing compound represented by formula 1 is selected from one of the group 1 compounds: [Compound Group 1] 15. A nitrogen-containing compound represented by Formula 1: [Formula 1] In Equation 1, X1 is NAr1Ar2, OAr3, or SAr4. Ar1 to Ar4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring. R1 to R4 are each independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 cyclic carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 30 cyclic carbon atoms, or bonded to an adjacent group to form a ring. a and b are each an independent integer selected from 0 to 3.

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