Organic electroluminescent device and compound for organic electroluminescent device

Abstract

To provide: a compound being an organic electroluminescence device material having high efficiency and long-life properties; and an organic electroluminescence device comprising the compound.SOLUTION: The present invention provides a compound represented by the chemical formula 1 in the figure, where L is a substituted or unsubstituted arylene group having 6-30 ring-forming carbon atoms, or a substituted or unsubstituted heteroarylene group having 2-30 ring-forming carbon atoms.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an organic electroluminescent device and a compound used therein, and more particularly to a compound used as a light-emitting material and an organic electroluminescent device containing the same. [Background technology]

[0002] Recently, organic electroluminescence displays (OLEDs) have been actively developed as image display devices. Unlike liquid crystal displays, OLEDs are so-called self-luminous displays that realize display by recombining holes and electrons injected from a first electrode and a second electrode in a light-emitting layer to cause a light-emitting material containing an organic compound in the light-emitting layer to emit light.

[0003] In order to apply organic electroluminescent devices to display devices, there is a demand for lower driving voltages, higher luminous efficiency, and longer life for the organic electroluminescent devices, and there is a continuous demand for the development of materials for organic electroluminescent devices that can stably achieve these demands.

[0004] In particular, in recent years, technologies related to phosphorescence that utilizes the energy of triplet states and delayed fluorescence that utilizes the phenomenon in which singlet excitons are generated by the collision of triplet excitons (triplet-triplet annihilation (TTA)) have been developed to realize highly efficient organic electroluminescent devices, and thermally activated delayed fluorescence (TADF) materials that utilize the delayed fluorescence phenomenon are being developed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 2019-0026796 [Patent Document 2] Korean Patent Publication No. 2009-0039598 [Patent Document 3] Korean Patent Publication No. 2015-0050570 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an organic electroluminescent device that exhibits excellent luminous efficiency and long life characteristics.

[0007] Another object of the present invention is to provide a compound which is a material for organic electroluminescent devices having high efficiency and long life characteristics. [Means for solving the problem]

[0008] One embodiment provides a compound represented by the following formula 1: [ka] In the above Chemical Formula 1, X 1 ~X 4 At least one of them is N and the rest are CR a where Y is O or S, and n is 1 or 2. L is a substituted or unsubstituted arylene group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 30 ring carbon atoms. R a is a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or is bonded to an adjacent group to form a ring, and Ar is represented by the following chemical formula 2. [ka] In the above Chemical Formula 2, W 1 ~W 8 are each independently N or CRb and Z is a single bond, O, or CR C R d and R b ~R d are each independently a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or are bonded to each other with adjacent groups to form a ring.

[0009] The above-mentioned Chemical Formula 1 is represented by the following Chemical Formula 1-1 or 1-2. [ka] [ka] In the above Chemical Formula 1-1 and Chemical Formula 1-2, X 1 ~X 4 , L, n, Z, W 1 ~W 8 is as defined in Chemical Formula 1 and Chemical Formula 2.

[0010] X 1 ~X 4 One of them is N and the rest is CR a or X 1 and X 4 are N and the rest are CR a and R a In the case of hydrogen atom, or R a -1~R a It is represented by one of the following values: [ka]

[0011] The above Chemical Formula 2 is represented by any one of the following Chemical Formulas 2-1 to 2-4. [ka] [ka] [ka] [ka] In the above Chemical Formula 2-4, R e is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms. 9 ~W 12 are each independently N or CR f and R f is a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, 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 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 30 ring carbon atoms, or is bonded to adjacent groups to form a ring. 1 ~W 8 is as defined in Chemical Formula 2 above.

[0012] The Ar is represented by any one of the following Ar-1 to Ar-6. [ka] [ka] In the above Ar-3, m1 and m2 are each independently 0 or 1; R b1 and Rb2 each independently represents a hydrogen atom, a deuterium atom, an arylamino group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms. L is represented by any one of the following L-1 to L-5. [ka] . The compound represented by Chemical Formula 1 is a green dopant that emits green light having a central wavelength of 500 nm to 550 nm.

[0013] The compound represented by Chemical Formula 1 is a blue dopant that emits blue light having a central wavelength of 450 nm or more and less than 500 nm.

[0014] The compound represented by Chemical Formula 1 is a host material.

[0015] The compound represented by the formula 1 has an absolute value of the difference between the lowest excited singlet energy level (S1) and the lowest excited triplet energy level (T1) (ΔE ST ) is less than 0.2 eV.

[0016] Another embodiment provides an organic electroluminescent device comprising a first electrode, a second electrode disposed on the first electrode, and an emissive layer disposed between the first electrode and the second electrode, the emissive layer comprising the compound of any one of the above-described embodiments.

[0017] The light-emitting layer includes a host and a dopant, and the host includes the compound.

[0018] The light-emitting layer emits delayed fluorescence, and the compound is a delayed fluorescence dopant.

[0019] The light emitting layer emits light having a central wavelength of 500 nm or more and 550 nm or less, or light having a central wavelength of 450 nm or more and less than 500 nm. Effect of the Invention

[0020] The organic electroluminescent device of the embodiment exhibits improved device characteristics of high efficiency and long life in the green or blue wavelength region.

[0021] The compound of one embodiment is contained in the light-emitting layer of an organic electroluminescent device to improve the life characteristics of the organic electroluminescent device and contribute to high efficiency. [Brief description of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view illustrating an organic electroluminescent device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Since the present invention can be modified in various ways and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text, but it is not intended to limit the present invention to the specific disclosed forms, but it should be understood that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0024] As used herein, when a component (or region, layer, portion, etc.) is referred to as being "on" or "coupled" to another component, it means that it may be directly disposed, coupled, or joined to the other component, or that a third component may be disposed therebetween.

[0025] The same reference numerals in the drawings refer to the same components, and in the drawings, thicknesses, proportions, and dimensions of the components are exaggerated for the purpose of effectively explaining the technical contents.

[0026] "And / or" includes all combinations of one or more of the associated construct.

[0027] Terms such as first, second, etc. are used to describe various components, but these components are not limited to the terms. The terms are used only for the purpose of distinguishing one component from another component. For example, the first component may be named the second component, and similarly, the second component may be named the first component, without departing from the scope of the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0028] In addition, terms such as "under", "below", "up" and "above" are used to describe the positional relationship of the components shown in the drawings. These terms are relative concepts and are described based on the directions shown in the drawings.

[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with the meaning in the context of the relevant art, and are expressly defined herein, unless interpreted in an idealized or overly formal sense.

[0030] It should be understood that the terms "comprise" or "have" specify the presence of a stated feature, number, step, operation, component, part, or combination thereof, but do not preclude the presence or additional possibility of one or more other features, number, steps, operations, components, parts, or combinations thereof.

[0031] Hereinafter, an organic electroluminescent device according to an embodiment of the present invention and an embodiment of a compound included therein will be described with reference to the drawings.

[0032] 1 to 4 are cross-sectional views each showing a schematic configuration of an organic electroluminescent device according to an embodiment of the present invention. Referring to Fig. 1 to Fig. 4, in an organic electroluminescent device 10 according to an embodiment, a first electrode EL1 and a second electrode EL2 are disposed facing each other, and an emission layer EML is disposed between the first electrode EL1 and the second electrode EL2.

[0033] In addition, the organic electroluminescent device 10 according to an embodiment further includes a plurality of functional layers between the first electrode EL1 and the second electrode EL2 in addition to the emission layer EML. The plurality of functional layers include a hole transport region HTR and an electron transport region ETR. That is, the organic electroluminescent device 10 according to an embodiment of the present invention includes a first electrode EL1, a hole transport region HTR, an emission layer EML, an electron transport region ETR, and a second electrode EL2, which are stacked in sequence. In addition, the organic electroluminescent device 10 according to an embodiment further includes a capping layer CPL disposed on the second electrode EL2.

[0034] The organic electroluminescent device 10 of one embodiment includes a compound according to one embodiment described below in the emitting layer EML disposed between the first electrode EL1 and the second electrode EL2. However, the embodiment is not limited thereto, and the organic electroluminescent device 10 of one embodiment may include a compound according to one embodiment described below included in the hole transport region HTR or the electron transport region ETR, which are multiple functional layers disposed between the first electrode EL1 and the second electrode EL2, in addition to the emitting layer EML.

[0035] Meanwhile, Fig. 2 shows a cross-sectional view of an organic electroluminescent device 10 according to an embodiment in which 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, in comparison with Fig. 1. Fig. 3 shows a cross-sectional view of an organic electroluminescent device 10 according to an embodiment in which 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, in comparison with Fig. 1. Fig. 4 shows a cross-sectional view of an organic electroluminescent device 10 according to an embodiment in which a capping layer CPL is disposed on the second electrode EL2, in comparison with Fig. 2.

[0036] The first electrode EL1 has conductivity. The first electrode EL1 is made of a metal, an alloy, or a conductive compound. The first electrode EL1 is an anode. The first electrode EL1 is a pixel electrode. The first electrode EL1 is a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. If the first electrode EL1 is a transmissive electrode, the first electrode EL1 includes a transparent metal oxide, such as ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), ITZO (indium tin zinc oxide), etc. If the first electrode EL1 is a semi-transmissive electrode or a reflective electrode, the first electrode EL1 includes Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, CR, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, or a compound or mixture thereof (for example, a mixture of Ag and Mg). Also, it has a multi-layer structure including a reflective film or semi-transparent film made of these materials, and a transparent conductive film made of ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), ITZO (indium tin zinc oxide), etc. For example, the first electrode EL1 may have a triple-layer structure of ITO / Ag / ITO, but is not limited thereto. The thickness of the first electrode EL1 is about 100 nm to about 1000 nm, for example, about 100 nm to about 300 nm.

[0037] The hole transport region HTR is disposed on the first electrode EL1. The hole transport region HTR includes at least one of a hole injection layer HIL, a hole transport layer HTL, a hole buffer layer (not shown), and an electron blocking layer EBL. The thickness of the hole transport region HTR may be, for example, about 5 nm to about 1,500 nm.

[0038] The hole transport region HTR may have a multi-layer structure having a layer of a single material, a layer of multiple different materials, or multiple layers of multiple different materials.

[0039] For example, the hole transport region HTR may have a structure of one layer of a hole injection layer HIL or a hole transport layer HTL, or may have a structure of one layer made of a hole injection material and a hole transport material. The hole transport region HTR may have a structure of one layer made of a plurality of different materials, or may have a structure of a hole injection layer HIL / hole transport layer HTL, a hole injection layer HIL / hole transport layer HTL / hole buffer layer (not shown), a hole injection layer HIL / hole buffer layer (not shown), a hole transport layer HTL / hole buffer layer, or a hole injection layer HIL / hole transport layer HTL / electron blocking layer EBL, which are stacked in order from the first electrode EL1, but the embodiment is not limited thereto.

[0040] The hole transport region HTR can be formed using various methods such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and Laser Induced Thermal Imaging (LITI).

[0041] The hole injection layer HIL may be, for example, a phthalocyanine compound such as copper phthalocyanine, DNTPD (N,N'-diphenyl-N,N'-bis-[4-phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4'-diamine), m-MTDATA (4,4',4"-[tris(3-methylphenyl)phenylamino]triphenylamine), TDATA (4,4',4"-tris(N,N-diphenylamino)triphenylamine), 2-TNATA (4,4',4"-tris{N,-(2-naphthyl)-N-phenylamino}-triphenylamine), PEDOT / PSS (poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonyl)sulfonyl) polyaniline / dodecylbenzenesulfonate), PANI / DBSA (polyaniline / dodecylbenzenesulfonic acid), PANI / CSA (polyaniline / camphorsulfonic acid), PANI / PSS ((polyaniline) / poly(4-styrenesulfonate)), NPB (N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine), triphenylamine-containing polyether ketone (TPAPEK), 4-isopropyl-4'-methyldiphenyliodonium [tetrakis(pentafluorophenyl)borate], HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile), and the like.

[0042] The hole transport layer HTL may include, for example, a carbazole derivative such as N-phenylcarbazole or polyvinylcarbazole, a fluorene derivative, a triphenylamine derivative such as TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1-biphenyl]-4,4'-diamine) or TCTA (4,4',4"-tris(N-carbazolyl)triphenylamine), NPB (N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine), TAPC (4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine]), or HMTPD (4,4'-bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl).

[0043] The thickness of the hole transport region HTR may be about 5 nm to about 10,000 nm, for example, about 10 nm to about 500 nm. The thickness of the hole injection layer HIL may be, for example, about 3 nm to about 100 nm, and the thickness of the hole transport layer HTL may be about 3 nm to about 100 nm. For example, the thickness of the electron blocking layer EBL may be about 1 nm to about 100 nm. If the thicknesses of the hole transport region HTR, the hole injection layer HIL, the hole transport layer HTL, and the electron blocking layer EBL satisfy the above-mentioned ranges, a satisfactory degree of hole transport characteristics can be obtained without a substantial increase in driving voltage.

[0044] In addition to the above-mentioned materials, the hole transport region HTR further includes a charge generating material to improve conductivity. The charge generating material is uniformly or non-uniformly dispersed in the hole transport region HTR. The charge generating material is, for example, a p-dopant. The p-dopant may be one of, but is not limited to, a quinone derivative, a metal oxide, and a cyano group-containing compound. For example, non-limiting examples of the p-dopant include, but are not limited to, quinone derivatives such as TCNQ (tetracyanoquinodimethane) and F4-TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), and metal oxides such as tungsten oxide and molybdenum oxide.

[0045] As described above, the hole transport region HTR includes at least one of a hole buffer layer (not shown) and an electron blocking layer EBL in addition to the hole injection layer HIL and the hole transport layer HTL. The hole buffer layer (not shown) compensates for the resonance distance according to the wavelength of light emitted from the emission layer EML to increase light emission efficiency. The material included in the hole buffer layer (not shown) is a material that can be included in the hole transport region HTR. The electron blocking layer EBL is a layer that serves to prevent the injection of electrons from the electron transport region ETR to the hole transport region HTR.

[0046] The light-emitting layer EML is disposed on the hole-transporting region HTR. The light-emitting layer EML has a thickness of, for example, about 10 nm to about 100 nm, or about 10 nm to about 40 nm. The light-emitting layer EML has a multilayer structure having one layer made of a single material, one layer made of multiple different materials, or multiple layers made of multiple different materials.

[0047] In the organic electroluminescent device 10 of one embodiment, the light-emitting layer EML includes the compound of one embodiment.

[0048] On the other hand, in this specification, "substituted or unsubstituted" means that it is substituted or not substituted with one or more substituents selected from the group consisting of a deuterium atom, a halogen atom, a cyano group, a nitro group, an amino group, a silyl group, an oxy group, a thio group, a sulfinyl group, a sulfonyl group, a carbonyl group, a boron group, a phosphine oxide group, a phosphine sulfide group, an alkyl group, an alkenyl group, an alkoxy group, a hydrocarbon ring group, an aryl group, and a heterocyclic group. In addition, each of these exemplified substituents may be substituted or unsubstituted. For example, a biphenylyl group may be interpreted as an aryl group, or as a phenyl group substituted with a phenyl group.

[0049] In this specification, "adjacent groups bond together to form a ring" means that adjacent groups bond together to form a substituted or unsubstituted hydrocarbon ring or a substituted or unsubstituted hetero ring. The hydrocarbon ring includes an aliphatic hydrocarbon ring and an aromatic hydrocarbon ring. The hetero ring includes an aliphatic hetero ring and an aromatic hetero ring. The ring formed by bonding adjacent groups together is a monocyclic or polycyclic ring. In addition, the ring formed by bonding together may be linked to another ring to form a spiro structure.

[0050] In this specification, the term "adjacent groups" refers to a substituent substituted on an atom directly bonded to the atom on which the substituent is substituted, another substituent substituted on an atom on which the substituent is substituted, or a substituent that is sterically most adjacent to the substituent. For example, two methyl groups in 1,2-dimethylbenzene are interpreted as "adjacent groups" to each other, and two ethyl groups in 1,1-diethylcyclopentene are interpreted as "adjacent groups" to each other.

[0051] In this specification, examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0052] In this specification, an alkyl group is linear, branched, or cyclic. The number of carbon atoms in an alkyl group is 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, i-butyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl ...3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, cyclopentyl, 3,3-dimethylbutyl, n-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, i-pentyl, Hexyl, 2-butylhexyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, t-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, cyclooctyl, n-nonyl, n-decyl, adamantyl n-butyldecyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl, 2-octyldecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldodecyl, 2-octyldecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl, 2-octylhexadecyl , n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, 2-ethylicosyl group, 2-butylicosyl group, 2-hexylicosyl group, 2-octylicosyl group, n-henicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, n-pentacosyl group, n-hexacosyl group, n-heptacosyl group, n-octacosyl group, n-nonacosyl group, and n-triacontyl group, but are not limited to these.

[0053] In the present specification, the hydrocarbon ring is an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring having 5 to 60, 5 to 30, or 5 to 20 ring carbon atoms. The hydrocarbon ring group is 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 ring carbon atoms of the hydrocarbon ring group is 5 to 60, 5 to 30, or 5 to 20.

[0054] In this specification, the aryl group means any functional group or substituent derived from an aromatic hydrocarbon ring. The aryl group is a monocyclic aryl group or a polycyclic aryl group. The number of ring carbon atoms of the aryl group is 6 to 30, 6 to 20, or 6 to 15. Examples of the aryl group include, but are not limited to, a phenyl group, a naphthyl group, a fluorenyl group, an anthracenyl group, a phenanthryl group, a biphenylyl group, a terphenylyl group, a quaterphenylyl group, a quinquephenylyl group, a sexiphenylyl group, a triphenylenyl group, a pyrenyl group, a benzofluoranthenyl group, and a chrysenyl group.

[0055] In this specification, a heterocyclic group refers to any functional group or substituent derived from a ring containing one or more of B, O, N, P, Si, and S as heteroatoms. Heterocyclic groups include aliphatic heterocyclic groups and aromatic heterocyclic groups. Aromatic heterocyclic groups are heteroaryl groups. The aliphatic heterocycles and aromatic heterocycles are monocyclic or polycyclic.

[0056] In this specification, the heterocycle includes one or more of B, O, N, P, Si, and S as a heteroatom. If the heterocycle includes two or more heteroatoms, the two or more heteroatoms may be the same or different. The heterocycle may be a monocyclic heterocycle or a polycyclic heterocycle, and includes heteroaryl. The number of ring carbon atoms of the heterocycle is 2 to 30, 2 to 20, or 2 to 10.

[0057] In this specification, an aliphatic heterocyclic group contains one or more heteroatoms selected from B, O, N, P, Si, and S. The number of ring carbon atoms in the aliphatic heterocyclic group is 2 to 30, 2 to 20, or 2 to 10. Examples of the aliphatic heterocyclic group include, but are not limited to, an oxiranyl group, a thiiranyl group, a pyrrolidinyl group, a piperidinyl group, a tetrahydrofuranyl group, a tetrahydrothiophenyl group, a thianyl group, a tetrahydropyranyl group, and a 1,4-dioxanyl group.

[0058] In this specification, the heteroaryl group includes one or more of B, O, N, P, Si, and S as heteroatoms. If the heteroaryl group includes two or more heteroatoms, the two or more heteroatoms may be the same or different. The heteroaryl group is a monocyclic heterocyclic group or a polycyclic heterocyclic group. The number of ring carbon atoms of the heteroaryl group is 2 to 30, 2 to 20, or 2 to 10. Examples of the heteroaryl group include a thiophenyl group, a furanyl group, a pyrrolyl group, an imidazolyl group, a triazolyl group, a pyridinyl group, a bipyridinyl group, a pyrimidinyl group, a triazinyl group, a triazolyl group, an acridinyl group, a pyridazinyl group, a quinolinyl group, a quinazolinyl group, a quinoxalinyl group, a phenoxanyl group, a phthalazinyl group, a pyridopyrimidinyl group, a pyridopyrazinyl group, a pyrazinopyrazinyl group, an isoquinolinyl group, an indolyl group, a carbazolyl group, an N-arylcarbazolyl group, an N- Examples of such groups include, but are not limited to, heteroarylcarbazolyl groups, N-alkylcarbazolyl groups, benzoxazolyl groups, benzimidazolyl groups, benzothiazolyl groups, benzocarbazolyl groups, benzothiophenyl groups, dibenzothiophenyl groups, thienothiophenyl groups, benzofuranyl groups, phenanthrolinyl groups, thiazolyl groups, isoxazolyl groups, oxazolyl groups, oxadiazolyl groups, thiadiazolyl groups, phenothiazinyl groups, dibenzosilolyl groups, and dibenzofuranyl groups.

[0059] In this specification, the number of carbon atoms of the amino group is not particularly limited, but is 1 to 30. The amino group includes an alkylamino group and an arylamino group. Examples of the amino group include, but are not limited to, a methylamino group, a dimethylamino group, a phenylamino group, a diphenylamino group, a naphthylamino group, a 9-methyl-anthracenylamino group, and a triphenylamino group. For example, the alkyl group in the alkylamino group is the same as the above-mentioned alkyl group, and the aryl group in the arylamino group is the same as the above-mentioned aryl group.

[0060] JPEG0007652381000013.jpg11154

[0061] The light emitting layer EML of the organic electroluminescent device 10 of one embodiment includes a compound represented by Chemical Formula 1 below. [ka] In Chemical Formula 1, X 1 ~X 4 At least one of them is N and the rest are CR a and Y is O or S. For example, X 1 ~X 4 One of the selected ones is N, and the rest are CR a or X 1 ~X 4 Two of the selected ones are N, and the rest are CR a may be also possible.

[0062] That is, the compound of one embodiment represented by Formula 1 includes an aza-type benzoxazole moiety or an aza-type benzothiazole moiety.

[0063] X 1 ~X 4 In this case, the rest that is not N is CR a and R ais a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or is bonded to adjacent groups to form a ring. For example, CR a In R a may be a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 20 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 20 ring carbon atoms, but the embodiment is not limited to these.

[0064] In one embodiment of the compound represented by formula 1, X 1 ~X 4 One of them is N and the rest is CR a or X 1 and X 4 are N, and the rest are CR a In these cases, R a is a hydrogen atom, or the following R a -1~R a It is represented by one of the following values: [ka]

[0065] On the other hand, X 1 ~X 4 At least one of the selected is N, and the rest is CR a When expressed as a are the same or at least one is different from each other.

[0066] In Chemical Formula 1, n is 1 or 2. Alternatively, L is a substituted or unsubstituted arylene group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 30 ring carbon atoms.

[0067] In Chemical Formula 1, L is represented by any one of the following formulae L-1 to L-5. [ka]

[0068] Specifically, in one embodiment of the compound represented by Formula 1, the linker L is a phenylene group or a pyridylene group.

[0069] In one embodiment of the compound represented by Chemical Formula 1, Ar is represented by Chemical Formula 2 below. [ka]

[0070] In Chemical Formula 2, W 1 ~W 8 are each independently N or CR b and Z is a single bond, O, or CR C R d R b ~R d are each independently a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or are bonded to each other with adjacent groups to form a ring.

[0071] For example, multiple adjacent R b are bonded to each other to form a hydrocarbon ring or a heterocycle. b are linked together to form a ring containing an indole moiety, or an aza-indole moiety.

[0072] In one embodiment, Chemical Formula 2 is represented by any one of Chemical Formulas 2-1 to 2-4 below. [ka] [ka] [ka] [ka]

[0073] In Chemical Formula 2-4, R e is a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms. For example, in Chemical Formula 2-4, R e may be a substituted or unsubstituted phenyl group.

[0074] In formula 2-4, W 9 ~W 12 are each independently N or CR f and R f is a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or is bonded to adjacent groups to form a ring.

[0075] For example, Chemical Formula 1 is represented by Chemical Formula 1-1 or Chemical Formula 1-2 below. [ka] [ka]

[0076] In Chemical Formula 1-1 and Chemical Formula 1-2, X 1 ~X 4 The same applies to the above-mentioned Chemical Formula 1 for n and L, and W 1 ~W 8 The same applies to the above-mentioned Chemical Formula 2 for Z.

[0077] Meanwhile, in Chemical Formula 1, Ar is represented by any one of the following Chemical Formulae Ar-1 to Ar-6. However, the embodiment is not limited thereto, and various examples of Ar may be provided, including heterocycles containing N as a ring-forming atom and in which the N atom is directly bonded to the linker L. [ka] [ka]

[0078] On the other hand, in Ar-3, m1 and m2 are each independently 0 or 1; R b1 and R b2 are each independently a hydrogen atom, a deuterium atom, an arylamino group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms. For example, R b1 and R b2 may each independently be a diphenylamino group or a phenyl group.

[0079] The compound of one embodiment is any one of the compounds shown in the following first compound group and second compound group. The organic electroluminescent device 10 of one embodiment contains at least one compound of the compounds shown in the first compound group and the second compound group in the emission layer EML.

[0080] [First compound group] [ka] [ka]

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[0081] [Second compound group]

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[0082] The compound according to one embodiment has a central emission wavelength (λ ) in the wavelength region of 450 nm or more. max For example, the compound of one embodiment represented by Chemical Formula 1 is a light-emitting material having a central emission wavelength in the wavelength range of 500 nm to 550 nm, or a light-emitting material having a central emission wavelength in the wavelength range of 450 nm to less than 500 nm. The compound of one embodiment represented by Chemical Formula 1 is a green dopant or a blue dopant.

[0083] In an embodiment of the organic electroluminescent device 10, the emission layer EML includes a host and a dopant, and includes the compound of the embodiment described above as the dopant. For example, in an embodiment of the organic electroluminescent device 10, the emission layer EML includes a delayed fluorescence host and a delayed fluorescence dopant, and may include the compound of the embodiment described above as the delayed fluorescence dopant. In particular, the emission layer EML includes at least one of the compounds described above as a thermally activated delayed fluorescence (TADF) dopant.

[0084] The compound of one embodiment represented by Chemical Formula 1 is a D(donor)-A(acceptor) type delayed fluorescent dopant material. In the compound of one embodiment represented by Chemical Formula 1, the aza-type benzoxazole partial structure or the aza-type benzothiazole partial structure corresponds to the electron acceptor, and the heterocyclic moiety represented by "Ar" corresponds to the electron donor. That is, the compound of one embodiment represented by Chemical Formula 1 is a DA-type thermally activated delayed fluorescent dopant.

[0085] In one embodiment, the compound represented by Formula 1 has an absolute value of the difference between the lowest excited singlet energy level (S1) and the lowest excited triplet energy level (T1) (ΔE ST ) is 0.2 eV or less and is used as a thermally activated delayed fluorescent dopant.

[0086] That is, the emissive layer EML of the organic electroluminescent device 10 according to an embodiment, which includes the compound according to an embodiment as an emissive layer EML material, emits delayed fluorescence. For example, the emissive layer EML may emit thermally activated delayed fluorescence.

[0087] The compound according to one embodiment has a novel compound structure including an aza-type benzoxazole partial structure or an aza-type benzothiazole partial structure as an electron acceptor, and is used as a thermally activated delayed fluorescent light-emitting material and is used as an emitting layer material of an organic electroluminescent device to improve the luminous efficiency of the organic electroluminescent device and increase its lifespan. In particular, the compound according to one embodiment is used as an emitting material that emits light in the green or blue wavelength region and shows excellent luminous efficiency.

[0088] In one embodiment, the emitting layer EML is a delayed fluorescent emitting layer, and the emitting layer EML includes a known host material and the compound of one embodiment described above. For example, in one embodiment, the emitting layer EML includes the compound of one embodiment as a dopant material, and Alq 3 (tris(8-hydroxyquinolino)aluminum), CBP (4,4'-bis(N-carbazolyl)-1,1'-biphenyl), PVK (poly(n-vinylcarbazole), ADN (9,10-di(naphthalen-2-yl)anthracene), TCTA (4,4',4"-tris(carbazol-9-yl)-triphenylamine), TPBi (1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene), TBADN (3-tert-butyl 4,4'-bis(9-carbazolyl)-2,2'-dimethyl-biphenyl), MADN (2-methyl-9,10-bis(naphthalen-2-yl)anthracene), DPEPO (bis[2-(diphenylphosphino)phenyl]ether oxide), CP1 (hexaphenylcyclotriphosphazene), UGH2 (1,4-bis(triphenylsilyl)benzene), DPSiO 3 (Hexaphenylcyclotrisiloxane), DPSiO 4(octaphenylcyclotetrasiloxane), or PPF (2,8-bis(diphenylphosphoryl)dibenzofuran), mCBP (3,3'-bis(N-carbazolyl)-1,1'-biphenyl), mCP (1,3-bis(N-carbazolyl)benzene), etc. However, the embodiment is not limited thereto, and may include a known delayed fluorescent host material in addition to the presented host material.

[0089] However, the embodiment is not limited thereto, and the compound of the embodiment may be used as a host material of the emitting layer EML. When the compound of the embodiment is used as a host material, a known dopant material may be used in addition to the compound of the embodiment in the emitting layer EML.

[0090] In the organic electroluminescent device 10 according to one embodiment, the emission layer EML further includes, as a known dopant material, a styryl derivative (e.g., 1,4-bis[2-(3-N-ethylcarbazolyl)vinyl]benzene (BCzVB), 4-(di-p-tolylamino)-4′-[(di-p-tolylamino)styryl]stilbene (DPAVB), N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalen-2-yl)vinyl)phenyl)-N-phenylbenzenamine (N-BDAVBi), perylene and its derivatives (e.g., 2,5,8,11-tetra-t-butylperylene (TBP)), pyrene and its derivatives (e.g., 1,1-dipyrene, 1,4-dipyrenylbenzene, 1,4-bis(N,N-diphenylamino)pyrene), and the like.

[0091] If the emitting layer EML emits green light, the emitting layer EML may be, for example, Alq 3 If the emitting layer EML emits green light, for example, the emitting layer EML includes the compound of one embodiment as a host material and Ir(ppy) as a known dopant material. 3These include metal complexes or organometallic complexes such as (fac-tris(2-phenylpyridine)iridium), coumarin and its derivatives, etc.

[0092] If the emitting layer EML emits blue light, the emitting layer EML further includes a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, DSB (distyryl-benzene), DSA (distyryl-arylene), PFO (polyfluorene)-based polymers, and PPV (poly(p-phenylenevinylene)-based polymers. If the emitting layer EML emits blue light, the emitting layer EML includes the compound of one embodiment as a host material and (4,6-F2ppy) as a known dopant material. 2 These include metal complex compounds such as Irpic, or organometallic complexes, and perylene and its derivatives.

[0093] Meanwhile, although not shown, the organic electroluminescent device 10 of an embodiment may include a plurality of light-emitting layers. The plurality of light-emitting layers are provided by being sequentially stacked, and for example, the organic electroluminescent device 10 including the plurality of light-emitting layers may emit white light. The organic electroluminescent device 10 including the plurality of light-emitting layers is an organic electroluminescent device having a tandem structure. When the organic electroluminescent device 10 includes a plurality of light-emitting layers, at least one of the light-emitting layers EML includes the compound according to the embodiment described above.

[0094] 1 to 4, an electron transport region ETR is provided on the light emitting layer EML. The electron transport region ETR includes at least one of a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL, but the embodiment is not limited thereto.

[0095] The electron transport region ETR may have a layer of a single material, a layer of multiple different materials, or a multi-layer structure having multiple layers of multiple different materials.

[0096] 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, or may have a single-layer structure consisting of an electron injection material and an electron transport material. The electron transport region ETR may have a single layer structure consisting of a plurality of different materials, or may have a structure of an electron transport layer ETL / electron injection layer EIL or a hole blocking layer HBL / electron transport layer ETL / electron injection layer EIL stacked in order from the light emitting layer EML, but is not limited thereto. The thickness of the electron transport region ETR may be, for example, about 30 nm to about 150 nm.

[0097] The electron transport region ETR can be formed using various methods such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0098] When the electron transport region ETR includes the electron transport layer ETL, the electron transport region ETR includes an anthracene-based compound. However, the electron transport region is not limited to these, and may include, for example, Alq 3(Tris(8-hydroxyquinolinato)aluminum), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 2,4,6-tris(3'-pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, 2-(4-(N-phenylbenzimidazol-1-yl)phenyl)-9,10-dinaphthylanthracene, TPBi(1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene), BCP(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bph en (4,7-diphenyl-1,10-phenanthroline), TAZ (3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), NTAZ (4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole), tBu-PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), BAlq (bis(2-methyl-8-quinolinolato-N1,O8)-(1,1'-biphenyl-4-olato)aluminum), Bebq 2 (beryllium bis(benzoquinoline-10-olate), ADN (9,10-di(naphthalen-2-yl)anthracene), BmPyPhB (1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene), and mixtures thereof. The thickness of the electron transport layer ETL is about 10 nm to about 100 nm, for example, about 15 nm to about 50 nm. When the thickness of the electron transport layer ETL satisfies the above-mentioned range, a satisfactory level of electron transport properties can be obtained without a substantial increase in driving voltage.

[0099] If the electron transport region ETR includes an electron injection layer EIL, the electron transport region ETR may be a metal halide such as LiF, NaCl, CsF, RbCl, or RbI, a lanthanum group metal such as Yb, or Li 2Metal oxides such as O, BaO, or Liq (lithium quinolate) may be used, but are not limited thereto. The electron injection layer EIL may also be made of a material in which an electron transport material and an insulating organo metal salt are mixed. The organo metal salt is a material having an energy band gap of about 4 eV or more. In detail, for example, the organo metal salt includes a metal acetate, a metal benzoate, a metal acetoacetate, a metal acetylacetonate, or a metal stearate. The thickness of the electron injection layer EIL is about 0.1 nm to about 10 nm, or about 0.3 nm to about 9 nm. If the thickness of the electron injection layer EIL satisfies the above-mentioned range, a satisfactory level of electron injection characteristics can be obtained without a substantial increase in driving voltage.

[0100] The electron transport region ETR includes the hole blocking layer HBL as described above. The hole blocking layer HBL may include, for example, at least one of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and Bphen (4,7-diphenyl-1,10-phenanthroline), but is not limited thereto.

[0101] The second electrode EL2 is disposed on the electron transport region ETR. The second electrode EL2 is a common electrode or a cathode. The second electrode EL2 is a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. If the second electrode EL2 is a transmissive electrode, the second electrode EL2 is made of a transparent metal oxide, such as ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), ITZO (indium tin zinc oxide), etc.

[0102] If the second electrode EL2 is a semi-transmissive electrode or a reflective electrode, the second electrode EL2 contains Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, CR, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, or a compound or mixture containing these (for example, a mixture of Ag and Mg).Also, the second electrode EL2 has a multi-layer structure including a reflective film or semi-transmissive film made of these materials, and a transparent conductive film made of ITO, IZO, ZnO, ITZO, or the like.

[0103] Although not shown, the second electrode EL2 is connected to an auxiliary electrode, and if the second electrode EL2 is connected to the auxiliary electrode, the resistance of the second electrode EL2 can be reduced.

[0104] On the other hand, a capping layer CPL is further disposed on the second electrode EL2 of the organic electroluminescent device 10 according to an embodiment. The capping layer CPL may be, for example, α-NPD, NPB, TPD, m-MTDATA, Alq 3 , CuPc, TPD15 (N4,N4,N4',N4'-tetra(biphenyl-4-yl)biphenyl-4,4'-diamine), TCTA (4,4',4"-tris(carbazol-9-yl)triphenylamine), N,N'-bis(naphthalen-1-yl), and the like.

[0105] The organic electroluminescent device 10 according to an embodiment of the present invention exhibits improved luminous efficiency by including the compound according to the embodiment in the emission layer EML disposed between the first electrode EL1 and the second electrode EL2. The compound according to the embodiment is a thermally activated delayed fluorescent dopant, and the emission layer EML includes the compound according to the embodiment and emits thermally activated delayed fluorescent light, thereby exhibiting good luminous efficiency characteristics. The compound according to the embodiment is included as a host material in the emission layer EML and is used together with a known fluorescent dopant material or a known phosphorescent dopant material to improve the luminous efficiency and lifetime of the organic electroluminescent device. In particular, the compound according to the embodiment is used as a dopant material in the emission layer EML to realize an organic electroluminescent device having excellent luminous efficiency and long lifetime characteristics even in the green or blue emission region.

[0106] Meanwhile, the compound according to the embodiment described above may be included in an organic layer other than the emission layer EML as a material for the organic electroluminescent device 10. For example, the organic electroluminescent device 10 according to the embodiment of the present invention may include the compound described above in at least one functional layer disposed between the first electrode EL1 and the second electrode EL2, or in a capping layer CPL disposed on the second electrode EL2.

[0107] The compound according to the embodiment has a novel compound structure including an aza-type benzoxazole partial structure or an aza-type benzothiazole partial structure as an electron acceptor, and is used as an emission layer material to contribute to high efficiency characteristics of an organic electroluminescent device. In addition, an organic electroluminescent device according to the embodiment including the compound according to the embodiment in the emission layer exhibits high efficiency characteristics in the green emission wavelength region or the blue emission wavelength region. EXAMPLES

[0108] Hereinafter, a compound according to an embodiment of the present invention and an organic electroluminescent device according to an embodiment of the present invention will be described in detail with reference to examples and comparative examples. The following examples are merely illustrative for the purpose of helping to understand the present invention, and the scope of the present invention is not limited thereto.

[0109] [Example] 1. Synthesis of Example Compounds First, the synthesis method of the compound according to the present embodiment will be specifically described by taking as an example the synthesis methods of compounds 1-1, 1-5, 1-43, 1-51, 1-53, 1-79, and 1-80. The synthesis method of the compound described below is an example, and the synthesis method of the compound according to the embodiment of the present invention is not limited to the following example.

[0110] (1) Synthesis of Compound 1-1 Compound 1-1 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 1 below. [Reaction Scheme 1] [ka]

[0111] <Synthesis of intermediate 1> 20.0 g (181.6 mmol) of 2-aminopyridin-3-ol and 45.1 g (181.6 mmol) of 4-iodobenzoic acid were mixed thoroughly in a 500 mL one-neck flask, and then POCl was added at 0 °C. 3 140mL was gradually added and stirred. The temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 43.0g (yield: 73.5%) of a white solid compound (intermediate 1).

[0112] <Synthesis of Compound 1-1> In a 500 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 1, 2.1 g (11.4 mmol) of phenoxazine, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 3 0.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 797.0 mg (yield: 19.4%) of compound 1-1 as a yellow solid.

[0113] (2) Synthesis of Compounds 1-5 Compound 1-5 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 2 below. [Reaction Scheme 2] [ka]

[0114] In a 500 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 1, 1.5 g (9.0 mmol) of 9H-carbazole, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 30.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.2 mg (yield: 35.1%) of compound 1-5 as a yellow solid.

[0115] (3) Synthesis of Compound 1-43 Compound 1-43 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 3 below. [Reaction Scheme 3] [ka]

[0116] <Synthesis of intermediate 2> 5.0 g (45.4 mmol) of 4-aminopyridin-5-ol and 11.3 g (45.4 mmol) of 4-iodobenzoic acid were mixed thoroughly in a 250 mL one-neck flask, and then POCl was added at 0 °C. 3 40mL was gradually added and stirred. The temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 7.2g (yield: 49.2%) of a white solid compound (intermediate 2).

[0117] <Synthesis of Compound 1-43> In a 240 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 2, 2.1 g (11.4 mmol) of phenoxazine, and Pd(dba). 2 0.31g (0.54mmol), Pd(dba) 2 0.31g (0.54mmol), P(tBu) 30.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.0 g (yield: 24.4%) of compound 1-43 as a yellow solid.

[0118] (4) Synthesis of Compound 1-47 Compound 1-47 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 4 below. [Reaction Scheme 4] [ka]

[0119] In a 250 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 2, 1.5 g (9.0 mmol) of 9H-carbazole, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 3 0.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 925 mg (yield: 28.5%) of compound 1-47 as a yellow solid.

[0120] (5) Synthesis of Compound 1-51 Compound 1-51 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 5 below. [Reaction Scheme 5] [ka]

[0121] In a 250 mL single-neck flask, add 1.5 g (4.5 mmol) of intermediate 2, 2.8 g (9.0 mmol) of 3,6-diphenyl-9H-carbazole, and Pd(dba). 2 0.3g (0.5mmol), P(t-Bu) 3 0.26g (0.5mmol, 50wt% toluene solution), 1.5g (15.8mmol) of NaOtBu, and 45mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by celite filtration. After completely removing the solvent, the mixture was purified by silica gel column chromatography (MC:HEX=1:8→1:1). The product thus obtained was solidified with (acetone:MeOH=2:1) ​​and then filtered to obtain 1.7g (yield: 73.4%) of compound 1-51 as an ocher solid.

[0122] (6) Synthesis of Compound 1-53 Compound 1-53 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 6 below. [Reaction Scheme 6] [ka]

[0123] In a 250 mL single-neck flask, add 1.5 g (4.5 mmol) of intermediate 2, 3.0 g (9.0 mmol) of N,N-diphenyl-9H-carbazol-2-amine, and Pd(dba). 2 0.3g (0.5mmol), P(t-Bu) 3 0.26g (0.5mmol, 50wt% toluene solution), 1.5g (15.8mmol) of NaOtBu, and 45mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by celite filtration. After completely removing the solvent, the mixture was purified by silica gel column chromatography (MC:HEX=1:8→1:1). The product thus obtained was solidified with (acetone:MeOH=2:1) ​​and then filtered to obtain 1.7g (yield: 71.2%) of compound 1-53 as an ocher solid.

[0124] (7) Synthesis of Compound 1-79 Compound 1-79 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 7 below. [Reaction Scheme 7] [ka]

[0125] <Synthesis of intermediate 3> 10.0 g (90.8 mmol) of 2-aminopyridin-3-ol and 22.5 g (90.8 mmol) of 3-iodobenzoic acid were mixed thoroughly in a 250 mL one-neck flask, and then POCl was added at 0 °C. 3 70mL was gradually added and stirred. Then, the temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 15.3g (yield: 52.3%) of a white solid compound (intermediate 3).

[0126] <Synthesis of Compound 1-79> In a 250 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 3, 2.1 g (11.4 mmol) of phenoxazine, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 3 0.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.2 g (yield: 29.3%) of compound 1-79 as a yellow solid.

[0127] (8) Synthesis of Compound 1-80 Compound 1-80 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 8 below. [Reaction Scheme 8] [ka]

[0128] In a 250 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 3, 1.5 g (9.0 mmol) of 9H-carbazole, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 3 0.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by celite filtration. After the solvent was completely removed, silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.4 g (yield: 42.6%) of compound 1-80 as a yellow solid.

[0129] (9) Synthesis of Compound 2-5 Compound 2-5 according to one embodiment can be synthesized, for example, by the steps of reaction scheme 9 below. [Reaction Scheme 9] [ka]

[0130] <Synthesis of intermediate 4> 22.9 g (181.6 mmol) of 2-aminopyridine-3-thiol and 45.1 g (181.6 mmol) of 4-iodobenzoic acid were mixed thoroughly in a 500 mL one-neck flask, and then POCl was added at 0 °C. 3 140mL was gradually added and stirred. The temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 43.8g (yield: 71.3%) of a white solid compound (intermediate 4).

[0131] <Synthesis of Compound 2-5> In a 250 mL one-neck flask, add 3.7 g (10.9 mmol) of intermediate 4, 1.5 g (9.0 mmol) of 9H-carbazole, and Pd(dba).2 0.31g (0.54mmol), P(tBu) 3 0.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.2 g (yield: 40.7%) of compound 2-5 as a yellow solid.

[0132] (10) Synthesis of Compound 2-53 Compound 2-53 according to one embodiment can be synthesized, for example, by the steps of Reaction Scheme 10 below. [Reaction Scheme 10] [ka]

[0133] <Synthesis of intermediate 5> 5.7 g (45.4 mmol) of 4-aminopyridine-3-thiol and 11.3 g (45.4 mmol) of 4-iodobenzoic acid were mixed thoroughly in a 250 mL one-neck flask, and then POCl was added at 0 °C. 3 40mL was gradually added and stirred. The temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 5.7g (yield: 37.7%) of a white solid compound (intermediate 5).

[0134] <Synthesis of compound 2-53> In a 250 mL one-neck flask, add 1.5 g (4.5 mmol) of intermediate 5, 3.0 g (9.0 mmol) of N,N-diphenyl-9H-carbazol-3-amine, and Pd(dba). 2 0.3g (0.5mmol), P(t-Bu) 30.26g (0.5mmol, 50wt% toluene solution), 1.5g (15.8mmol) of NaOtBu, and 45mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by celite filtration. After completely removing the solvent, the mixture was purified by silica gel column chromatography (MC:HEX=1:8→1:1). The product thus obtained was solidified with (acetone:MeOH=2:1) ​​and then filtered to obtain 1.5g (yield: 61.5%) of compound 2-53 as an ocher solid.

[0135] (11) Synthesis of Compound 2-79 Compound 2-79 according to one embodiment can be synthesized, for example, by the steps of reaction scheme 11 below. [Reaction Scheme 11] [ka]

[0136] <Synthesis of intermediate 6> 10.0 g (90.8 mmol) of 2-aminopyridine-3-thiol and 22.5 g (90.8 mmol) of 3-iodobenzoic acid were mixed thoroughly in a 250 mL one-neck flask, and then POCl was added at 0 °C. 3 70mL was gradually added and stirred. Then, the temperature was raised to 90℃ and the reaction was allowed to proceed for 12 hours. After the reaction was completed, the reaction mixture was cooled to room temperature and gradually added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 18.2g (yield: 62.2%) of a white solid compound (intermediate 6).

[0137] <Synthesis of Compound 2-79> In a 250 mL single-neck flask, add 3.5 g (10.9 mmol) of intermediate 6, 2.1 g (11.4 mmol) of phenoxazine, and Pd(dba). 2 0.31g (0.54mmol), P(tBu) 30.53mL (1.1mmol, 50wt% toluene solution), 2.1g (21.7mmol) of NaOtBu, and 54mL of xylene were refluxed and stirred for a whole day. After cooling to room temperature, impurities were removed by filtration through Celite. After the solvent was completely removed, the residue was purified by silica gel column chromatography (EA: CHCl 3 =1:20) The resulting solid was treated with acetone and filtered to obtain 1.4 g (yield: 33.8%) of compound 2-79 as a yellow solid.

[0138] 2. Compound Evaluation The fluorescent emission characteristics of the compound of the example were evaluated. The emission characteristics of the comparative example compounds were also evaluated together with the compound of the example. The compounds used for the evaluation are shown below.

[0139] (Compounds used in evaluating luminescence properties) [ka] [ka] (Comparative Example Compound Used for Evaluating Light Emitting Properties) [ka]

[0140] Table 1 shows the ΔE ST The characteristic evaluation results are shown in Table 1. ST is the difference between the lowest singlet excitation energy level (S1 level) and the lowest triplet excitation energy level (T1 level), and was calculated using Gaussian calculation (basis set B3LYP / 6-31G*). The emission wavelengths of the example compounds and the comparative compounds were confirmed using emission spectra. [Table 1]

[0141] Referring to the results in Table 1, the compound of one embodiment is used as a light-emitting material that emits blue or green light. In addition, the compound of one embodiment has a small ΔE of less than 0.20 eV. ST It is believed that the compound has a value and can be used as a delayed fluorescent material.

[0142] 3. Preparation and evaluation of organic electroluminescence devices 3-1. Example A of an organic electroluminescent device containing the compound of one embodiment An organic electroluminescent device of an example containing the compound of an example as a host material of the light-emitting layer was produced by the following method.

[0143] (Fabrication of organic electroluminescent devices) The ITO-patterned glass substrate was washed with ultrapure water and ultrasonically cleaned, then irradiated with UV for 30 minutes and then treated with ozone. Next, HT1 was evaporated to a thickness of 120 nm, and HT2 was evaporated to a thickness of 10 nm to form a hole transport region.

[0144] Next, when forming the light-emitting layer, the compound of one embodiment or the compound of the comparative example and 4CzIPN were co-deposited in a ratio of 80:20 to form a layer with a thickness of 40 nm. That is, in the light-emitting layer formed by co-deposition, the compound of the present invention was mixed with 4CzIPN and deposited in each embodiment, and the comparative example was mixed with 4CzIPN and deposited in each comparative example.

[0145] Next, a 30 nm thick layer was formed on the emissive layer by vapor deposition of a 5:5 mixture of ET and Liq, and a 1 nm thick layer of LiQ was formed on the emissive layer to form the electron transport region. A 10 nm thick second electrode was then formed with Mg:Ag (10:1).

[0146] In the examples, the hole transport region, the light emitting layer, the electron transport region, and the second electrode were formed using a vacuum deposition apparatus.

[0147] The materials for the hole transport region, the electron transport region, and the dopant materials used in the fabrication of the organic electroluminescent device are shown below. [ka] [ka]

[0148] The compounds used in Examples 1-1 and 1-2 are shown below. [ka]

[0149] (Evaluation of the characteristics of organic electroluminescent devices) Table 2 shows a comparison of the efficiency, lifespan, and luminescent color of the fabricated organic electroluminescent devices. In the characteristic evaluation results for the examples and comparative examples shown in Table 2, the efficiency was 2 In the evaluation of the characteristics of the organic electroluminescent device, the efficiency and lifetime of the examples are shown as relative values ​​when the efficiency and lifetime of Comparative Example 1-1 are set to 100%.

[0150] In Example 1-1 and Comparative Example 1-2, Compound 1-51 and Compound 1-58 were used as the host material of the light-emitting layer, respectively. In Comparative Example 1-1, mCBP, a known host material, was used as the host material of the light-emitting layer. [Table 2]

[0151] Referring to the results in Table 2, it can be seen that Examples 1-1, 1-2, and Comparative Example 1-1 all emit light in the green wavelength region. It can be seen that Examples 1-1 and 1-2 have improved efficiency and life characteristics compared to Comparative Example 1-1.

[0152] Therefore, the compound according to one embodiment can be used as a host material for an emission layer that emits light in the green wavelength region, and shows improved luminous efficiency and excellent life characteristics compared to the case of using a conventional host material.

[0153] 3-2. Example B of an organic electroluminescent device containing the compound of one embodiment An organic electroluminescent device of an example containing the compound of an example as a dopant material in the light-emitting layer was produced by the following method.

[0154] (Fabrication of organic electroluminescent devices) The ITO-patterned glass substrate was washed with ultrapure water and ultrasonically cleaned, then irradiated with UV for 30 minutes and then treated with ozone. Next, mHT1 was evaporated to a thickness of 120 nm, and HT2 was evaporated to a thickness of 10 nm to form the hole transport region.

[0155] Next, when forming the light-emitting layer, the compound of one embodiment or the compound of the comparative example and mCBP were co-deposited in a ratio of 20:80 to form a layer with a thickness of 40 nm. That is, in the light-emitting layer formed by co-deposition, the compound of the embodiment and mCBP were mixed and deposited in the examples, and the compound of the comparative example was mixed and deposited in the comparative example.

[0156] Next, a 30 nm thick layer was formed on the emissive layer by vapor deposition of a 5:5 mixture of ET and Liq, and a 1 nm thick layer of Liq was formed on the emissive layer to form the electron transport region. A 10 nm thick second electrode was then formed with Mg:Ag (10:1).

[0157] In the examples, the hole transport region, the light emitting layer, the electron transport region, and the second electrode were formed using a vacuum deposition apparatus.

[0158] (Evaluation of the characteristics of organic electroluminescent devices) Table 3 shows the efficiency, lifetime, and luminous color of the fabricated organic electroluminescent devices. In the characteristic evaluation results for the examples and comparative examples shown in Table 3, the efficiency was 2 In addition, in the evaluation of the characteristics of the organic electroluminescent device, the efficiency and lifetime of the examples are shown as relative values ​​when the efficiency and lifetime of Comparative Example 2-1 or Comparative Example 3-1 are set to 100%.

[0159] In the evaluations shown in Table 3 below, Examples 2-1 to 2-4 and Comparative Examples 2-1 and 2-2 show the evaluation results of organic electroluminescent devices that emit light in the green wavelength region, and Examples 3-1 to 3-5 and Comparative Example 3-1 show the evaluation results of organic electroluminescent devices that emit light in the blue wavelength region. In Examples 2-1 to 2-4, Comparative Examples 2-1 and 2-2, Examples 3-1 to 3-5, and Comparative Example 3-1, mCBP, a known host material, was used as the host material of the light-emitting layer. [Table 3]

[0160] Referring to the results in Table 3, it can be seen that the examples are organic electroluminescent devices that emit green or blue light, and the compounds according to one embodiment can be used as green dopants that emit green light, or blue dopants that emit blue light.

[0161] Furthermore, referring to the results in Table 3, it can be seen that Examples 2-1 to 2-4 show improved and superior efficiency characteristics and long life characteristics compared to Comparative Examples 2-1 and 2-2, and Examples 3-1 to 3-5 show improved and superior efficiency characteristics and long life characteristics compared to Comparative Example 3-1.

[0162] Therefore, referring to the evaluation results in Table 3, it can be seen that the compound according to one embodiment is used as an emission layer dopant of an organic electroluminescent device and emits green or blue light. In addition, compared to the comparative example compound, the compound according to one embodiment contains an aza-type benzoxazole partial structure, and therefore, when used as an emission layer dopant material, it has the effect of improving the efficiency and life characteristics of the organic electroluminescent device.

[0163] The compound of the embodiment has a novel compound structure including an aza-type benzoxazole partial structure or an aza-type benzothiazole partial structure as an electron acceptor, and is used as an emission layer material to contribute to high efficiency and long life characteristics of an organic electroluminescent device. In addition, an organic electroluminescent device of the embodiment including the compound of the embodiment in the emission layer exhibits high efficiency characteristics and improved life characteristics in the green emission wavelength region or the blue emission wavelength region.

[0164] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or those having ordinary knowledge in the art that various modifications and variations of the present invention may be made without departing from the spirit and technical scope of the present invention as set forth in the claims below.

[0165] Therefore, the technical scope of the present invention should be determined not by the contents described in the detailed description of the specification, but by the claims. [Explanation of symbols]

[0166] 10: Organic electroluminescent element EL1: First electrode EL2: second electrode HTR: hole transport region EML: Light-emitting layer ETR: Electron transport region

Claims

1. A compound represented by the following chemical formula 1: 【Chemistry 1】 In the above Chemical Formula 1, X １ ~X ４ One of them is N and the rest is CR ａ and Y is O or S; n is 1 or 2; L is a phenylene group; R ａ is a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, or is bonded to an adjacent group to form a ring, Ar is represented by the following chemical formula 2: 【Chemistry 2】 In the above Chemical Formula 2, W １ ~W ８ is CR ｂ and Z is a single bond or O; R ｂ ~R ｄ each independently represents a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms, The compound represented by Chemical Formula 1 is any one of the compounds of the following first compound group or second compound group: [First compound group] 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 【Chemistry 17】 【Chemistry 18】 【Chemistry 19】 【Chemistry 20】 【Chemistry 23】 【Chemistry 24】 【Chemistry 25】 [Second compound group] 【Chemistry 26】 【Chemical 27】 【Chemistry 28】 【Chemical Formula 29】 【Chemistry 30】 【Chemistry 31】 【Chemistry 32】 【Chemical 33】 【Chemical 36】 【Chemical 37】 【Chemical 38】 。

2. The compound according to claim 1, wherein the formula 1 is represented by the following formula 1-1 or 1-2: 【Chemistry 3】 【Chemistry 4】 In the formula 1-1 and the formula 1-2, X １ ~X ４ , L, n, Z, W １ ~W ８ is as defined in Formula 1 and Formula 2.

3. X １ ~X ４ One of them is N and the rest is CR ａ and R ａ is a hydrogen atom, or the following R ａ -1 to R ａ The compound according to claim 1, which is represented by any one of the following formulas: 【Chemistry 5】 。

4. The compound according to claim 1, wherein the formula 2 is represented by the following formula 2-1 or 2-3: 【Chemistry 6】 【Chemistry 8】 In the formula 2-1 and the formula 2-3, W １ ~W ８ is as defined in Chemical Formula 2 above.

5. The compound according to claim 1, wherein Ar is represented by the following Ar-1 or Ar-3: 【Chemistry 10】 In Ar-3, m1 and m2 each independently represent 0 or 1. R ｂ１ and R ｂ２ each independently represents a hydrogen atom, a deuterium atom, an arylamino group having 6 to 30 ring carbon atoms, or a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms.

6. The compound according to claim 1, wherein L is represented by the following L-1: 【Chemistry 12】 。

7. The compound according to claim 1 , wherein the compound represented by Chemical Formula 1 is a green dopant that emits green light having a center wavelength of 500 nm to 550 nm.

8. The compound according to claim 1 , wherein the compound represented by Chemical Formula 1 is a blue dopant that emits blue light having a central wavelength of 450 nm or more and less than 500 nm.

9. The compound according to claim 1 , wherein the compound represented by Chemical Formula 1 is a host material.

10. The compound represented by the formula 1 has an absolute value of the difference between the lowest excited singlet energy level (S1) and the lowest excited triplet energy level (T1) (ΔE ＳＴ 2. The compound according to claim 1, wherein the electron transport coefficient is 0.2 eV or less.

11. A first electrode; A second electrode disposed on the first electrode; An organic electroluminescent device comprising: a light-emitting layer disposed between the first electrode and the second electrode, the light-emitting layer comprising the compound according to claim 1 .

12. The light-emitting layer comprises a host and a dopant, The organic electroluminescent device according to claim 11 , wherein the host comprises the compound.

13. The light-emitting layer emits delayed fluorescence, The organic electroluminescent device according to claim 11, wherein the compound is a delayed fluorescent dopant.

14. The organic electroluminescent device according to claim 11, wherein the light emitting layer emits light having a central wavelength of 500 nm or more and 550 nm or less, or light having a central wavelength of 450 nm or more and less than 500 nm.

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