Organic electroluminescent device

Abstract

To provide an organic electroluminescent element with the excellent luminous efficiency characteristic, and a polycyclic compound that is a material for an organic electroluminescent element with an excellent life characteristic and a high efficiency characteristic.SOLUTION: An organic electroluminescent element includes a first electrode EL1, a second electrode EL2, and a light-emitting layer EML disposed between the first electrode and the second electrode. The light-emitting layer has high luminous efficiency and a long life characteristic by containing a polycyclic compound expressed by a following formula. In the formula below, X1 to X4 independently represent O, S, or NRa.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an organic electroluminescent device and a polycyclic compound used therein, and more particularly to a polycyclic 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 order to realize highly efficient organic electroluminescent devices, technologies related to phosphorescence emission that utilizes the energy of triplet states and delayed fluorescence emission that utilizes the phenomenon in which singlet excitons are generated by the collision of triplet excitons (TTA) have been developed recently, and development of thermally activated delayed fluorescence (TADF) materials that utilize the delayed fluorescence phenomenon is also underway. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 2019-0042791 [Patent Document 2] Korean Patent Publication No. 2017-0121345 [Patent Document 3] JP 2018-043984 A 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 characteristics.

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

[0008] According to one embodiment, there is provided a polycyclic compound represented by the following Chemical Formula 1: [ka] ...(chemical formula 1) In Chemical Formula 1, X 1 ~X 4 each independently represents O, S, or NR a where a and b are each independently an integer of 0 to 3, and c and d are each independently an integer of 0 to 4. 1 ~R 4 , and R a are each independently a hydrogen atom, a deuterium atom, a halogen atom, 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 alkenyl group having from 2 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. 1 ~R 4 , and R a can each be linked to an adjacent group to form a ring.

[0009] R1 ~R 4 may each independently be a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted arylamino group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl group having from 2 to 20 carbon atoms.

[0010] R a may be a substituted or unsubstituted phenyl group.

[0011] Each of a to d may be independently 0 or 1.

[0012] R 1 ~R 4 , and R a Adjacent groups selected from among the above may be bonded to each other to form a heterocycle having 2 to 10 ring carbon atoms.

[0013] X 3 and X 3 Adjacent to R 3 , or X 4 and X 4 Adjacent to R 4 may contain an indole group formed by bonding together.

[0014] The formula 1 may be represented by any one of the following formulas 1-1 to 1-5. [ka] ...(chemical formula 1-1) [ka] ...(chemical formula 1-2) [ka] ...(chemical formula 1-3) [ka] ...(chemical formula 1-4) [ka] ...(chemical formula 1-5) In the above Chemical Formulae 1-2 to 1-5, a1, b1, and c1 may each independently be 0 or 1. In the above Chemical Formulae 1-1 to 1-5, X 1 ~X 4 , R 1 , R 2 , and R 3 is as defined in Chemical Formula 1 above.

[0015] The polycyclic compound represented by Chemical Formula 1 may be a blue dopant.

[0016] The polycyclic compound represented by Chemical Formula 1 may be a thermally activated delayed fluorescent material.

[0017] According to another embodiment, there is provided an organic electroluminescent device including a first electrode, a second electrode disposed on the first electrode, and a light-emitting layer disposed between the first electrode and the second electrode and including the polycyclic compound according to the embodiment described above. The first electrode and the second electrode each independently include at least one selected from Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, In, Sn, and Zn, a compound of two or more selected from these elements, a mixture of two or more selected from these elements, or an oxide thereof.

[0018] The light-emitting layer may include a host and a dopant, and the host may include the polycyclic compound.

[0019] The light-emitting layer may emit delayed fluorescence.

[0020] The light emitting layer may emit light having a central wavelength of 420 nm or more and 470 nm or less. Effect of the Invention

[0021] An organic electroluminescent device according to an embodiment of the present invention exhibits improved device characteristics with high efficiency in the blue emission wavelength region.

[0022] The polycyclic compound according to one embodiment has a plate-like skeleton structure containing a pyridine core, and is included in the light-emitting layer of an organic electroluminescent device, thereby contributing to improving the efficiency of the organic electroluminescent device. [Brief description of the drawings]

[0023] [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

[0024] Since the present invention can be modified in various ways and can have various forms, specific embodiments are shown 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, and 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.

[0025] 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 connected to the other component, or that a third component may be disposed therebetween.

[0026] The same reference numerals refer to the same components. Also, in the drawings, thicknesses, proportions and dimensions of the components are exaggerated for the purpose of effectively explaining the technical contents.

[0027] "And / or" includes all combinations of one or more of the associated construct.

[0028] Terms such as first and second are used to describe various components, but the components are not limited to the terms. The terms are used only to distinguish one structural element from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the scope of the present invention. A singular expression includes a plural expression, unless the context clearly indicates otherwise.

[0029] In addition, terms such as "under", "below", "up" and "above" are used to describe the relationship between components shown in the drawings. The terms are relative concepts and are described based on the directions shown in the drawings.

[0030] 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.

[0031] It should be understood that the terms "comprise" or "have" imply the presence of any feature, numeral, step, operation, component, part, or combination thereof set forth in the specification above, but do not preclude the presence or additional possibility of one or more other features, numerals, steps, operations, components, parts, or combinations thereof.

[0032] In the present specification, "substituted or unsubstituted" means that the group is substituted or unsubstituted 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 boryl 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 the substituents exemplified above 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.

[0033] In this specification, "adjacent groups bond together to form a ring" means 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 bonded to another ring to form a spiro structure or a condensed ring.

[0034] 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.

[0035] In this specification, examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In this specification, a heterocyclic group means any functional group or substituent derived from a ring containing one or more of B, O, N, P, Si, and S as heteroatoms. The heterocyclic group includes an aliphatic heterocyclic group and an aromatic heterocyclic group. The aromatic heterocyclic group is a heteroaryl group. The aliphatic heterocycle and the aromatic heterocycle are monocyclic or polycyclic. When the heterocycle contains two or more heteroatoms, the two or more heteroatoms may be the same or different from each other. The heterocycle may be a monocyclic or polycyclic heterocycle, and is a concept including a heteroaryl. The number of ring carbon atoms of the heterocycle is 2 to 30, 2 to 20, or 2 to 10.

[0040] 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.

[0041] In this specification, the heteroaryl group includes one or more of B, O, N, P, Si, and S as a heteroatom. When the heteroaryl group includes two or more heteroatoms, the two or more heteroatoms may be the same or different. The heteroaryl group may be 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 alkyl 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.

[0042] 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.

[0043] JPEG0007659383000007.jpg9150

[0044] 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.

[0045] 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 of the present invention, 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.

[0046] 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. The organic electroluminescent device 10 according to an embodiment may also include a capping layer CPL disposed on the second electrode EL2.

[0047] The organic electroluminescent device 10 according to an embodiment includes a polycyclic compound according to an embodiment described later in the emission layer EML disposed between the first electrode EL1 and the second electrode EL2. However, the embodiment of the present disclosure is not limited thereto, and the organic electroluminescent device 10 according to an embodiment may include a compound according to an embodiment described later 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 emission layer EML.

[0048] Fig. 2 is 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, unlike Fig. 1. Fig. 3 is 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, unlike Fig. 1. Fig. 4 is 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, unlike Fig. 2.

[0049] The first electrode EL1 has conductivity. The first electrode EL1 is made of a metal alloy or a conductive compound. The first electrode EL1 is an anode. Also, 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, for example, 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, an alloy of Ag and Mg). The first electrode EL1 may have a multi-layer structure including a reflective film or semi-transmissive film made of the above-mentioned material, 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.

[0050] The hole transport region HTR is provided 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 1500 nm.

[0051] The hole transport region HTR may have a single layer of a single material, a single layer of a plurality of different materials, or a multi-layer structure having a plurality of layers of a plurality of different materials.

[0052] 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, or a single layer structure of a hole injection material and a hole transport material. The hole transport region HTR may have a single layer structure of a plurality of different materials, or 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 present embodiment is not limited thereto.

[0053] 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).

[0054] The hole injection layer HTL 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-styrenesulfonate), PANI / DBSA (polyaniline / dodecyl dodecyl ether), benzenesulfonic acid), PANI / CSA (polyaniline / camphorsulfonic acid), PANI / PSS ((polyaniline) / poly(4-styrenesulfonate)), NPB (N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine), NPD (N,N'-di(-1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl-4,4'-diamine), polyether ketone with triphenylamine (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.

[0055] The hole transport layer HTL may be, for example, a carbazole derivative such as N-phenylcarbazole or polyphenylcarbazole, 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), or a tetraphenylamine derivative such as NPB (N,N'-di(naphthalene-1-yl)-N ,N'-diphenyl-benzidine), TAPC (4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine]), HMTPD (4,4'-bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl), mCP (1,3-bis(N-carbazolyl)benzene), CzSi (9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), and the like.

[0056] The thickness of the hole transport region HTR may be about 5 nm to about 1000 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. When 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, sufficient hole transport properties can be obtained without a substantial increase in driving voltage.

[0057] In addition to the above-mentioned materials, the hole transport region HTR may further include 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 quinone derivatives, metal oxides, and cyano group-containing compounds, but is not limited thereto. For example, the p-dopant may be, but is not limited to, quinone derivatives such as TCNQ (tetracyanoquinodimethane) and F4-TCNQ (2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane), metal oxides such as tungsten oxide and molybdenum oxide, and the like.

[0058] 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 transport layer HTL and the hole injection layer HIL. 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.

[0059] The light-emitting layer EML is provided on the hole transport 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 30 nm. The light-emitting layer EML has a multilayer structure having a single layer made of a single material, a single layer made of a plurality of different materials, or a plurality of layers made of a plurality of different materials.

[0060] In the organic electroluminescent device 10 according to an embodiment, the emission layer EML includes the polycyclic-containing compound according to an embodiment.

[0061] The emission layer EML of the organic electroluminescent device 10 according to an embodiment includes a polycyclic compound represented by Chemical Formula 1 below according to an embodiment. [ka] ...(chemical formula 1)

[0062] In Chemical Formula 1, X 1 No~ 4 each independently represents O, S, or NR a In one embodiment of the polycyclic compound, X 1 ~X 4 may all be the same, or at least one may be different from the rest.

[0063] In addition, in Chemical Formula 1, R 1 ~R 4 , and R a are each independently a hydrogen atom, a deuterium atom, a halogen atom, 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 alkenyl group having from 2 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. 1 ~R 4 , and R a may each be bonded to an adjacent group to form a ring.

[0064] In Chemical Formula 1, a and b are each independently an integer of 0 or 3 or less, and c and d are each independently an integer of 0 to 4. On the other hand, in Chemical Formula 1, if a to d are each an integer of 2 or more, then multiple R 1 ~R 4 may each be the same, or at least one may be different from the rest.

[0065] The polycyclic compound according to an embodiment represented by Chemical Formula 1 has a planar structure containing pyridine. That is, the polycyclic compound according to an embodiment has a plurality of hexagonal rings bonded to each other, and in particular has a fused ring structure in which rings on both sides of pyridine are bonded to each other.

[0066] In addition, the polycyclic compound according to one embodiment includes a B (boron) atom in each of the rings adjacent to the pyridine ring. The polycyclic compound according to one embodiment includes a ring-forming atom N (nitrogen) of the pyridine ring, ring-forming atoms B and X of the rings bonded to both sides of the pyridine ring. 1 ~X 4 As a result, when the polycyclic compound according to the embodiment is used as an emission layer material of an organic electroluminescent device, it exhibits good life characteristics and contributes to increasing the efficiency of the device.

[0067] In one embodiment of the polycyclic compound, R 1 ~R 4 may each independently be a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted arylamino group, or a substituted or unsubstituted heteroaryl group having from 2 to 20 carbon atoms. For example, R 1 ~R 4 may each independently be a t-butyl group, a diphenylamino group, or a substituted or unsubstituted carbazolyl group, although the present embodiment is not limited thereto.

[0068] In the polycyclic compound according to one embodiment represented by Chemical Formula 1, a to d may each independently be 0 or 1. When a to d are 0, the polycyclic compound according to one embodiment is not substituted. That is, when a to d are 0, R 1 ~R 4 means that all of a to d are hydrogen atoms. In one embodiment, any one of a to d may be 1, and the rest may be 0.

[0069] In Chemical Formula 1, R 1 ~R 4 , and R a Adjacent groups selected from may be bonded to each other to form a heterocycle having 2 to 10 ring carbon atoms. For example, R 1~ R 4 , and R aAdjacent groups selected from may be bonded to each other to form a ring, or may be fused to the ring represented by Chemical Formula 1 to form a fused ring.

[0070] In the polycyclic compound according to one embodiment of the present invention represented by Chemical Formula 1, X 3 and X 3 Adjacent to R 3 may be bonded to each other to form a ring. 4 and X 4 Adjacent to R 4 may be bonded to each other to form a ring. 3 and X 3 Adjacent to R 3 A ring formed by bonding together, and X 4 and X 4 Adjacent to R 4 may include any ring formed by bonding together X 3 and X 3 Adjacent to R 3 A ring formed by bonding together, and X 4 and X 4 Adjacent to R 4 The ring formed by bonding together may contain an indolyl group. 3 and X 3 Adjacent to R 3 A ring formed by bonding together, and X 4 and X 4 Adjacent to R 4 The ring formed by bonding to each other is fused to the ring represented by Chemical Formula 1 to form a fused ring.

[0071] In the polycyclic compound represented by chemical formula 1, X 1 ~X 4 At least one of the following is NR a If expressed as R a is a substituted or unsubstituted phenyl group.

[0072] In one embodiment, Chemical Formula 1 may be represented by any one of Chemical Formulas 1-1 to 1-5 below. [ka] ...(chemical formula 1-1) [ka] ...(chemical formula 1-2) [ka] ...(chemical formula 1-3) [ka] ...(chemical formula 1-4) [ka] ...(chemical formula 1-5)

[0073] In Chemical Formula 1-2 to Chemical Formula 1-5, a1, b1, and c1 are each independently 0 or 1. In Chemical Formula 1-1 to Chemical Formula 1-5, X 1 ~X 4 , R 1 , and R 2 The same applies as described above for Chemical Formula 1.

[0074] In Chemical Formula 1-2 to Chemical Formula 1-5, if a1, b1, and c1 are 1, R 1 ~R 3 may be independently represented by any one of the following S-1 to S-3, but the present embodiment is not limited thereto. [ka]

[0075] The polycyclic compound according to an embodiment may be any one of the compounds shown in the following first compound group. The organic electroluminescent device 10 according to an embodiment includes at least one polycyclic compound among the polycyclic compounds shown in the first compound group in the emission layer EML. [First compound group]

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[0076] The polycyclic compound according to one embodiment is a light-emitting material having a central emission wavelength in the wavelength region of 420 nm to 470 nm. The polycyclic compound represented by Chemical Formula 1 is a blue dopant.

[0077] In the organic electroluminescent device 10 according to an embodiment, the emission layer EML includes a host and a dopant, and includes the polycyclic compound according to the embodiment described above as a dopant. For example, in the organic electroluminescent device 10 according to an embodiment, the emission layer EML includes a delayed fluorescent host and a delayed fluorescent dopant, and may include the polycyclic compound according to the embodiment described above as a delayed fluorescent dopant. In particular, the emission layer EML includes at least one of the polycyclic compounds according to the embodiment described above as a thermally activated delayed fluorescence (TADF) dopant.

[0078] That is, the emitting layer EML of the organic electroluminescent device 10 according to an embodiment, which includes the polycyclic compound according to an embodiment as an emitting layer EML material, emits delayed fluorescence. For example, the emitting EML may emit thermally activated delayed fluorescence.

[0079] However, the present embodiment is not limited thereto, and the polycyclic compound according to an embodiment may be used as a host material in the organic electroluminescent device 10 according to an embodiment.

[0080] The polycyclic compound according to an embodiment has a plate-like compound structure formed by condensing a plurality of rings, and in particular, contains pyridine at the center of the composite ring. The polycyclic compound according to an embodiment has a robust molecular structure with the polycyclic structure fixed by the pyridine ring, and thus exhibits highly reliable compound properties. In addition, the polycyclic compound according to an embodiment includes both an electron withdrawing group (EWG) atom and an electron donating group (EDG) atom as ring-forming atoms, and thus multiple resonance is further activated within a molecule of one compound, and thus has a high f value (oscillation strength). As a result, the polycyclic compound according to an embodiment accelerates the light emission speed, and when used as a light-emitting layer material, contributes to improving the life of an organic electroluminescent device. In addition, the polycyclic compound according to an embodiment exhibits a low ΔEst value and can be used as a thermally activated delayed fluorescent light-emitting material, thereby contributing to improving the light-emitting efficiency of an organic electroluminescent device.

[0081] In the organic electroluminescent device 10 according to an embodiment, the emission layer EML contains a known host material and the polycyclic compound according to the embodiment described above. For example, in an embodiment, the emission layer EML contains 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), 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 present embodiment is not limited to these, and may contain a known delayed fluorescent host material in addition to the above-mentioned host materials.

[0082] The organic electroluminescent device 10 according to an embodiment may include an anthracene derivative represented by the following chemical formula A in the emission layer EML. [ka] ...(Chemical formula A)

[0083] In the chemical formula A, R 31 ~R 40are each independently a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkyl group having from 1 to 10 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, and may be bonded to an adjacent group to form a ring. 31 ~R 40 When linked to adjacent groups, they form a saturated or unsaturated hydrocarbon ring.

[0084] In Chemical Formula A, c and d each independently represent an integer of 0 or more and 5 or less.

[0085] Chemical formula A is represented by any one of the following chemical formulas 3-1 to 3-16. [ka] JPEG0007659383000032.jpg42167 [ka] [ka] [ka] [ka]

[0086] The organic electroluminescent device 10 according to an embodiment may further include a known dopant material in the emission layer EML in addition to the polycyclic compound according to an embodiment. Known dopant materials include styryl derivatives (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, etc.).

[0087] Meanwhile, although not shown, the organic electroluminescent device 10 according to an embodiment may include a plurality of light-emitting layers. The plurality of light-emitting layers may be 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 polycyclic compound according to the embodiment described above.

[0088] 1 to 4, the electron transport region ETR is provided on the emission 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 present embodiment is not limited thereto.

[0089] The electron transport region ETR has a single layer made of a single material, a single layer made of a plurality of different materials, or a multilayer structure having a plurality of layers made of a plurality of different materials.

[0090] 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 made of an electron injection material and an electron transport material. The electron transport region ETR may have a single layer structure made 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 100 nm to about 150 nm.

[0091] 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).

[0092] 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 thereto, 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), Bphen (4,7-diphenyl-1,10-phenanthroline), TSPO1 (diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide), 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 electron transport layer ETL has a thickness of about 10 nm to about 100 nm, for example, about 15 nm to about 50 nm. When the thickness of the electron transport layer HTL satisfies the above-mentioned range, sufficient electron transport properties can be obtained without a substantial increase in driving voltage.

[0093] When 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 lanthanide metal such as Yb, or Li 2 Metal oxides such as O, BaO, or LiQ (lithium quinolate) may be used, but are not limited thereto. The electron injection layer EIL may also include 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 metal acetate, metal benzoate, metal acetoacetate, metal acetylacetonate, or 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. When the thickness of the electron injection layer EIL satisfies the above-mentioned range, sufficient electron injection characteristics can be obtained without a substantial increase in driving voltage.

[0094] 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.

[0095] The second electrode EL2 is provided 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), or ITZO (indium tin zinc oxide).

[0096] 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). The second electrode EL2 may have a multi-layer structure including a reflective film or semi-transmissive film made of the above material, and a transparent conductive film made of ITO, IZO, ZnO, ITZO, or the like.

[0097] Although not shown, the second electrode EL2 may be electrically connected to an auxiliary electrode, If the second electrode EL2 is connected to the auxiliary electrode, the resistance of the second electrode EL2 can be reduced.

[0098] A capping layer CPL may be further disposed on the second electrode EL2 of the organic electroluminescent device 10 according to the embodiment. The capping layer CPL may include, for example, α-NPD, NPB, TPD, m-MTDATA, Alq3, 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), or the like.

[0099] The organic electroluminescent device 10 according to an embodiment of the present invention exhibits improved luminous efficiency by including the polycyclic compound according to an embodiment described above in the emission layer EML disposed between the first electrode EL1 and the second electrode EL2. The polycyclic compound according to an embodiment is a thermally activated delayed fluorescence dopant, and the emission layer EML includes the polycyclic compound according to an embodiment and emits thermally activated delayed fluorescence, thereby exhibiting good luminous efficiency characteristics. In particular, the polycyclic compound according to an embodiment is used as a blue dopant material in the emission layer EML, thereby realizing an organic electroluminescent device having excellent luminous efficiency in the blue emission region.

[0100] Meanwhile, the polycyclic 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 an embodiment of the present invention may include the polycyclic 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.

[0101] The polycyclic compound according to the embodiment includes a pyridine ring and has a plate-like structure in which a plurality of rings are bonded to the pyridine ring and fixed. The polycyclic compound according to the embodiment includes pyridine having acceptor properties in the core, and when used as an emission layer material, contributes to high efficiency characteristics of an organic electroluminescent device. In addition, an organic electroluminescent device according to the embodiment including the polycyclic compound according to the embodiment in an emission layer exhibits high efficiency characteristics in the blue emission wavelength region. EXAMPLES

[0102] Hereinafter, a polycyclic compound according to an embodiment of the present invention and an organic electroluminescent device according to an embodiment will be described in detail with reference to examples and comparative examples. The following examples are merely illustrative for aiding in understanding the present invention, and the scope of the present invention is not limited thereto.

[0103] 1. Synthesis of polycyclic compounds according to one embodiment First, the synthesis method of the polycyclic compound according to the present embodiment will be specifically described by taking as examples the synthesis methods of compounds 7, 10, 13, 15, and 16. The synthesis method of the polycyclic compound described below is merely an example, and the synthesis method of the polycyclic compound according to the embodiment of the present invention is not limited to the following examples.

[0104] (1) Synthesis of compound 7 Compound 7 according to one embodiment can be synthesized, for example, according to the scheme shown in Reaction Scheme 1 below. [Reaction Scheme 1] [ka]

[0105] <Synthesis of intermediate 7-1> 2,6-Difluoropyridine (1 eq), 3,5-dibromophenol (3 eq), and cesium carbonate (3 eq) were dissolved in NMP, and then stirred at 190°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was dried under reduced pressure to remove the NMP. The organic layer was then washed three times with ethyl acetate and water, and the resulting organic layer was dissolved in MgSO 4 The mixture was dried at 40° C. and then dried under reduced pressure, and purified by column chromatography to obtain intermediate 7-1 (yield: 60%).

[0106] <Synthesis of intermediate 7-2> Intermediate 7-1 (1 eq), aniline (3 eq), tris(dibenzylideneacetone)dipalladium(0) (0.1 eq), tri-tert-butylphosphine (0.2 eq), and sodium t-butoxide (4 eq) were dissolved in toluene and stirred at 110°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was washed three times with ethyl acetate and water, and the resulting organic layer was extracted with MgSO4 The mixture was dried at 40° C. and then dried under reduced pressure. The mixture was purified by column chromatography and recrystallized (dichloromethane:n-hexane) to obtain intermediate 7-2 (yield: 51%).

[0107] <Synthesis of intermediate 7-3> Intermediate 7-2 (1 eq), iodobenzene (5 eq), tris(dibenzylideneacetone)dipalladium(0) (0.2 eq), tri-tert-butylphosphine (0.4 eq), and sodium t-butoxide (4 eq) were dissolved in toluene and stirred at 110°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was washed three times with ethyl acetate and water, and the resulting organic layer was extracted with MgSO 4 The mixture was dried at 40° C. and then dried under reduced pressure, and purified by column chromatography to obtain intermediate 7-3 (yield: 72%).

[0108] <Synthesis of compound 7> After dissolving intermediate 7-3 (1 eq) in o-dichlorobenzene, the flask was cooled to 0°C under a nitrogen atmosphere and then cooled with BBr 3 (4eq) was gradually added. After the dropwise addition was completed, the temperature was raised to 190 degrees Celsius and stirred for 24 hours. After cooling to 0 degrees, triethylamine was gradually added dropwise to the flask until the heat generation ceased. After the reaction was terminated, hexane was added to precipitate and the solid matter was filtered. The obtained solid matter was purified by silica filtration and further purified by MC / Hex recrystallization to obtain compound 7. Next, final purification was performed by sublimation purification. (Yield after sublimation: 5%)

[0109] (2) Synthesis of compound 10 Compound 10 according to one embodiment can be synthesized, for example, according to the scheme shown in Reaction Scheme 2 below. [Reaction Scheme 2] [ka]

[0110] <Synthesis of intermediate 10-1> 2-Bromo-6-fluoropyridine (1 eq), N1,N1,N3,N3,N5-pentaphenylbenzene-1,3,5-triamine (1 eq), tris(dibenzylideneacetone)dipalladium(0) (0.1 eq), tri-tert-butylphosphine (0.2 eq), and sodium t-butoxide (3 eq) were dissolved in toluene, and the mixture was stirred at 110°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was washed three times with dichloromethane and water, and the resulting organic layer was diluted with MgSO 4 After drying at 40° C., the mixture was dried under reduced pressure and purified by column chromatography to obtain intermediate 10-1 (yield: 81%).

[0111] <Synthesis of intermediate 10-2> Intermediate 10-1 (1 eq), 3,5-dibromophenol (2 eq), and cesium carbonate (2 eq) were dissolved in NMP, and then stirred at 190°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was dried under reduced pressure to remove the NMP. Next, the mixture was washed three times with ethyl acetate and water, and the resulting organic layer was dissolved in MgSO 4 After drying at 40° C., the mixture was dried under reduced pressure. The mixture was purified by column chromatography to obtain intermediate 10-2 (yield: 68%).

[0112] <Synthesis of intermediate 10-3> Intermediate 10-2 (1 eq), aniline (3 eq), tris(dibenzylideneacetone)dipalladium(0) (0.1 eq), tri-tert-butylphosphine (0.2 eq), and sodium t-butoxide (4 eq) were dissolved in toluene and stirred at 110°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was washed three times with ethyl acetate and water, and the resulting organic layer was extracted with MgSO 4 After drying at 40° C., the mixture was dried under reduced pressure. The mixture was purified by column chromatography and recrystallized (dichloromethane:n-hexane) to obtain intermediate 10-3 (yield: 61%).

[0113] <Synthesis of intermediate 10-4> Intermediate 10-4 was obtained in the same manner as intermediate 7-3, except that intermediate 10-3 and iodobenzene (3 eq) were used. (Yield: 82%)

[0114] <Synthesis of compound 10> Compound 10 was obtained in the same manner as compound 7, except that intermediate 10-4 was used. (Yield after sublimation: 6%)

[0115] (3) Synthesis of compound 13 Compound 13 according to one embodiment can be synthesized, for example, according to the scheme shown in Reaction Scheme 3 below. [Reaction Scheme 3] [ka]

[0116] <Synthesis of intermediate 13-1> Intermediate 13-1 was obtained in the same manner as intermediate 7-2, except that 2,6-dibromopyridine (1 eq) and aniline (3 eq) were used (yield: 71%).

[0117] <Synthesis of intermediate 13-2> Intermediate 13-2 was obtained in the same manner as intermediate 10-4, except that intermediate 13-1 (1 eq) and 5-bromo-N1,N1,N3,N3-tetraphenylbenzene-1,3-diamine (2 eq) were used (yield: 63%).

[0118] <Synthesis of compound 13> Compound 13 was obtained in the same manner as compound 7, except that intermediate 13-2 was used. (Yield after sublimation: 8%)

[0119] (4) Synthesis of compound 15 Compound 15 according to one embodiment can be synthesized, for example, according to the scheme shown in Reaction Scheme 4 below. [Reaction Scheme 4] [ka]

[0120] <Synthesis of intermediate 15-1> Intermediate 13-1 (1 eq), 1,3-dibromo-5-(tert-butyl)benzene (2 eq), tris(dibenzylideneacetone)dipalladium(0) (0.1 eq), tri-tert-butylphosphine (0.2 eq), and sodium t-butoxide (3 eq) were dissolved in toluene, and the mixture was stirred at 90°C for 12 hours under a nitrogen atmosphere. After cooling, the mixture was washed three times with ethyl acetate and water, and the resulting organic layer was extracted with MgSO 4 After drying at 40°C, the mixture was dried under reduced pressure. The mixture was purified by column chromatography to obtain intermediate 15-1 (yield: 66%).

[0121] <Synthesis of intermediate 15-2> Intermediate 15-2 was obtained in the same manner as intermediate 7-2, except that intermediate 15-1 (1 eq) and diphenylamine (2.5 eq) were used. (Yield: 74%)

[0122] <Synthesis of compound 15> Compound 15 was obtained in the same manner as compound 7, except that intermediate 15-2 was used. (Yield after sublimation: 4%)

[0123] (5) Synthesis of compound 16 Compound 16 according to one embodiment can be synthesized, for example, according to the scheme of Reaction Scheme 5 below. [Reaction Scheme 5] [ka]

[0124] <Synthesis of intermediate 16-1> Intermediate 16-1 was obtained in the same manner as intermediate 10-4, except that intermediate 13-1 (1 eq) and 5-bromo-N1,N1,N3,N3-tetraphenylbenzene-1,3-diamine (1 eq) were used (yield: 60%).

[0125] <Synthesis of intermediate 16-2> Intermediate 16-2 was obtained in the same manner as intermediate 10-4, except that intermediate 16-1 (1 eq) and 3-bromo-5-phenoxy-N,N-diphenylaniline (1 eq) were used (yield: 71%).

[0126] <Synthesis of compound 16> Compound 16 was obtained in the same manner as compound 7, except that intermediate 16-2 was used. (Yield after sublimation: 2%)

[0127] (6) Identification of the synthesized compounds The molecular weights and NMR analysis results of the synthesized compounds are shown in Table 1 below. [Table 1]

[0128] 2. Evaluation of polycyclic compounds The following Table 2 shows the ΔE st The values ​​and emission wavelengths are shown.

[0129] ΔE in Table 2 st The values ​​were calculated by the ab initio molecular orbital method. In detail, the calculations were performed using Gaussian09 manufactured by Gaussian Corporation with B3LYP / 6-31G(d). ΔE st indicates the difference between the lowest singlet excited energy level (S1 level) and the lowest triplet excited energy level (T1 level).

[0130] The comparative compounds used as comparative examples are as follows. [ka] [Table 2]

[0131] Referring to the results in Table 2, the compounds used in the examples have smaller ΔE st That is, the example compounds have small ΔE st It is believed that the above-mentioned materials can be used as TADF materials by having such a value.

[0132] It was also confirmed that the example compounds emit light in the wavelength region of 450 nm or less and can therefore be used as blue dopants.

[0133] 3. Creation and evaluation of organic electroluminescent devices An organic electroluminescent device according to an embodiment, which includes a polycyclic compound according to an embodiment in a light-emitting layer, was produced by the following method.

[0134] (Fabrication of organic electroluminescent devices) The ITO-patterned glass substrate was washed with ultrapure water and ultrasonically, then irradiated with UV for 30 minutes and then treated with ozone. Next, NPD was deposited to a thickness of 30 nm, TCTA was deposited to a thickness of 20 nm, and CzSi was deposited to a thickness of 10 nm to form a hole transport region.

[0135] Next, when forming the light-emitting layer, the polycyclic compound according to one embodiment or the comparative compound and mCP were co-deposited at a ratio of 1:99 to form a layer having a thickness of 20 nm. That is, in the light-emitting layer formed by co-deposition, the polycyclic compounds 7, 10, 13, 15, and 16 were mixed with mCP and deposited in the examples, and the comparative compounds C1 and C3 were mixed with mCP and deposited in the comparative examples.

[0136] Next, a 20 nm thick layer of TSPO1 was formed on the light-emitting layer, followed by a 30 nm thick layer of TPBi and a 1 nm thick layer of LiF to form an electron transport region, and then a 300 nm thick second electrode was formed from aluminum (Al).

[0137] 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.

[0138] The hole transport region materials and electron transport region materials used in the fabrication of the organic electroluminescent devices are listed below. [ka] [ka]

[0139] (Evaluation of the characteristics of organic electroluminescent devices) The efficiency and luminescence color of the fabricated organic electroluminescent devices are compared in Table 3 below. To evaluate the characteristics of the fabricated organic electroluminescent devices, 2 The driving voltage, current efficiency, and maximum quantum efficiency were measured. The driving voltage and current efficiency of the organic electroluminescent device were measured using a source meter (Keithley Instrument, 2400 series), and the maximum quantum efficiency was measured using an external quantum efficiency measurement device C9920-2-12 manufactured by Hamamatsu Photonics. In evaluating the maximum quantum efficiency, the luminance / current density was measured using a luminance meter with calibrated wavelength sensitivity, and the maximum quantum efficiency was converted by assuming an angular luminance distribution (Lambertian) assuming a perfect diffuse reflection surface. The characteristic evaluation results of the organic electroluminescent device are shown in Table 3 below. [Table 3]

[0140] Referring to the results in Table 3, it can be seen that the Examples have lower driving voltages and higher current efficiencies than the Comparative Examples. It can also be seen that the Examples emit light in the blue wavelength region, and both the current efficiency and external quantum efficiency are generally improved compared to the Comparative Examples.

[0141] The polycyclic compound according to an embodiment has a plate-like structure capable of multiple resonance, includes a robust structure bonded and fixed by pyridine rings, 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 according to an embodiment, which includes the polycyclic compound according to an embodiment in an emission layer, exhibits high efficiency characteristics in a blue emission wavelength region.

[0142] Although the present invention has been described above with reference to embodiments thereof, it should be understood that a person skilled in the art or having ordinary knowledge in the art can make various modifications and variations to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims below.

[0143] 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]

[0144] 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 first electrode; a hole injection layer disposed on the first electrode; a hole transport layer disposed on the hole injection layer; an electron blocking layer disposed on the hole transport layer; a light-emitting layer disposed on the electron blocking layer and including at least one polycyclic compound selected from the following first compound group; an electron transport region disposed over the light emitting layer; a second electrode disposed on the electron transport region; a capping layer disposed on the second electrode; Including, The organic electroluminescent device, wherein the first electrode and the second electrode each independently contain at least one selected from Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, In, Sn, and Zn, a compound of two or more selected from these, a mixture of two or more selected from these, or an oxide of these. [First compound group] 【Chemistry 1】 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】

2. The light-emitting layer comprises a host and a dopant, The organic electroluminescent device according to claim 1 , wherein the dopant comprises the polycyclic compound.

3. The organic electroluminescent device according to claim 1 , wherein the light-emitting layer emits delayed fluorescence.

4. The organic electroluminescent device according to claim 1 , wherein the light emitting layer emits light having a central wavelength of 420 nm or more and 470 nm or less.

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