Organic electroluminescent device and polycyclic compound for organic electroluminescent device

Abstract

To provide an organic electroluminescent element improved in luminous efficiency.SOLUTION: The organic electroluminescent element includes a first electrode EL1 and a second electrode EL2 facing each other and a light-emitting layer EML arranged between the first electrode and the second electrode. The light-emitting layer exhibits improved luminous efficiency by containing a polycyclic compound represented by the following chemical formula 1. In the chemical formula 1, at least one of L and A contains an electron-accepting substituent, and D is a specific substituent.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 and the like, OLEDs are so-called self-emissive display devices that realize display by causing luminescent materials containing organic compounds in the luminescent layer to emit light by recombining holes and electrons injected from the first and second electrodes in the luminescent layer.

[0003] In order to apply organic electroluminescent devices to display devices, there is a demand for lower driving voltages, higher luminous efficiency, and longer lifespans of 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, which utilizes the energy of triplet states, and delayed fluorescence, which utilizes the phenomenon in which singlet excitons are generated by the collision of triplet excitons (Triplet-triplet annihilation, TTA), have been developed recently. Development is also underway on thermally activated delayed fluorescence (TADF) materials that utilize the delayed fluorescence phenomenon. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2017-0030130 [Patent Document 2] Korean Patent Registration No. 10-1305934 [Patent Document 3] U.S. Patent No. 10,211,411 [Patent Document 4] Korean Patent Publication No. 10-2015-0130797 [Patent Document 5] Korean Patent Publication No. 10-2017-0111387 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 with improved luminous efficiency.

[0007] Another object of the present invention is to provide a polycyclic compound capable of improving the luminous efficiency of an organic electroluminescent device. [Means for solving the problem]

[0008] An organic electroluminescent device according to an embodiment of the present invention includes a first electrode, a second electrode facing the first electrode, and an emitting layer disposed between the first electrode and the second electrode, the emitting layer including a polycyclic compound represented by Chemical Formula 1 below: [ka] ...(chemical formula 1) In Chemical Formula 1, L is a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms; A is 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; at least one of L and A contains an electron acceptor substituent; n is an integer of from 0 to 3; l is 1 or 2; and D is represented by Chemical Formula 2 below. [ka] ...(chemical formula 2) In Chemical Formula 2, X is O, S, NR1, or SiR2R3, and Y1 to Y 11 are each independently N or CR4, R1 to R4 are each independently a single bond, 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 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, R1 to R4 may be bonded to adjacent groups to form a ring, and any one of R1 to R4 is a site bonded to L in Chemical Formula 1. Therefore, among R1 to R4, the group bonded to L in Chemical Formula 1 is a single bond.

[0009] The light-emitting layer may emit delayed fluorescence.

[0010] The light-emitting layer may be a delayed fluorescent light-emitting layer including a host and a dopant. The dopant may include a polycyclic compound represented by Chemical Formula 1.

[0011] The light-emitting layer may include a host having a first lowest triplet excitation energy level, a first dopant having a second lowest triplet excitation energy level lower than the first lowest triplet excitation energy level, and a second dopant having a third lowest triplet excitation energy level lower than the second lowest triplet excitation energy level. The first dopant may include a polycyclic compound represented by Chemical Formula 1.

[0012] The first dopant may be a delayed fluorescent dopant, and the second dopant may be a fluorescent dopant.

[0013] The organic electroluminescent device according to one embodiment of the present invention may further include a hole transport region disposed between the first electrode and the light emitting layer, and an electron transport region disposed between the light emitting layer and the second electrode.

[0014] The A may be represented by any one of the following chemical formulas A-1 to A-3. [ka] ...(Chemical formula A-1) [ka] ...(Chemical formula A-2) [ka] ...(chemical formula A-3) In the chemical formulas A-1 to A-3, W1 to W 12 are each independently N or CR 13 Z1 is O or S, and Z2 is O, S, or NR 14 , C.R. 15 R 16 , or SiR 17 R 18 where m is 0 or 1, and R5 to R 18 are each independently a single bond, 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; 18 may bond with adjacent groups to form a ring, and R to R 12 At least one of R5 to R6 is a halogen atom or a cyano group. 18 Any one of R5 to R6 is a bonded site to L in Chemical Formula 1. 18 Among these, the group bonded to L in Chemical Formula 1 is a single bond.

[0015] The A may be represented by any one of the following chemical formulas A-1-1 to A-3-3. [ka] ...(Chemical formula A-1-1) [ka] ...(Chemical formula A-1-2) [ka] ...(Chemical formula A-2-1) [ka] ...(Chemical formula A-2-2) [ka] ...(Chemical formula A-3-1) [ka] ...(Chemical formula A-3-2) [ka] ...(Chemical formula A-3-3) In the chemical formulas A-1-1 to A-3-3, W1 to W 12 , Z1, Z2, m, R5~R 18 is as defined in Chemical Formulae A-1 to A-3 above.

[0016] The polycyclic compound represented by Chemical Formula 1 may be represented by Chemical Formula 3 below. [ka] ...(chemical formula 3) In Chemical Formula 3, L1 and L2 are each independently a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms, D1 is represented by Chemical Formula 2, and D2 is an electron donor substituent. In Chemical Formula 3, A is as defined in Chemical Formula 1.

[0017] D2 may be a substituted or unsubstituted arylamino group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

[0018] The D may be represented by the following chemical formulas 2-1 to 2-5. [ka] ...(chemical formula 2-1) [ka] ...(Chemical formula 2-2) [ka] ...(Chemical formula 2-3) [ka] ...(Chemical formula 2-4) [ka] ...(chemical formula 2-5) In the above Chemical Formula 2-1 to Chemical Formula 2-5, Y1 to Y 11 and R1 to R4 are as defined in Chemical Formula 2 above.

[0019] L may be a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridinylene group, a substituted or unsubstituted triazinylene group, a substituted or unsubstituted benzoxazolylene group, a substituted or unsubstituted benzothiazolylene group, a substituted or unsubstituted benzimidazolylene group, a substituted or unsubstituted imidazopyridinylene group, a substituted or unsubstituted oxazolopyridinylene group, a substituted or unsubstituted thiazolopyridinylene group, a substituted or unsubstituted dibenzoborinylene group, or a substituted or unsubstituted dibenzooxaborinylene group.

[0020] In an organic electroluminescent device according to an embodiment of the present invention, the first electrode and the second electrode may each independently include any one selected from the group consisting of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, In, Zn, and Sn, a compound of two or more selected from the group consisting of these elements, a mixture of two or more selected from the group consisting of these elements, or an oxide of one or more selected from the group consisting of these elements.

[0021] The polycyclic compound according to one embodiment of the present invention is represented by Chemical Formula 1.

[0022] The polycyclic compound represented by Chemical Formula 1 may have an absolute value of the difference between the lowest singlet excitation energy level (S1) and the lowest triplet excitation energy level (T1) of 0.2 eV or less. [Effects of the Invention]

[0023] The organic electroluminescent device according to one embodiment exhibits improved device characteristics, such as high luminous efficiency in the blue region.

[0024] The polycyclic compound according to one embodiment contributes to improving the efficiency of an organic electroluminescent device by being contained in the light-emitting layer of the organic electroluminescent device. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view schematically illustrating an organic electroluminescent device according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an organic electroluminescent device according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view schematically illustrating an organic electroluminescent device according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view schematically illustrating an organic electroluminescent device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The above-mentioned objects, other objects, features, and advantages of the present invention will be easily understood through the accompanying drawings and the following preferred embodiments. However, the present invention is not limited to the embodiments described herein and may be realized in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content will be thorough and complete, and so that the concept of the present invention will be fully conveyed to those skilled in the art.

[0027] Throughout the drawings, like reference numerals are used to refer to like elements. In the accompanying drawings, the dimensions of structures are exaggerated for clarity. Terms such as "first," "second," etc. are used to describe various elements, but the elements are not limited to these terms. These terms are used only to distinguish one structural element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the present invention. The singular term "a" includes the plural term unless the context clearly dictates otherwise.

[0028] As used herein, terms such as "comprise" or "have" specify the presence of a feature, numeral, step, operation, component, part, or combination thereof described above in the specification, but should be understood not to preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or combinations thereof. Furthermore, when a layer, film, region, plate, or other part is described as being "on" another part, this includes not only when it is "directly on" the other part, but also when there is another part between them. Conversely, when a layer, film, region, plate, or other part is described as being "under" the other part, this includes not only when it is "directly under" the other part, but also when there is another part between them.

[0029] JPEG0007797095000019.jpg6133

[0030] On the other hand, in this specification, "substituted or unsubstituted" means being 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, or being unsubstituted. Furthermore, 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.

[0031] In this specification, "adjacent groups bond to each other to form a ring" means that adjacent groups bond to each other to form a substituted or unsubstituted hydrocarbon ring, or a substituted or unsubstituted heterocycle. Hydrocarbon rings include aliphatic hydrocarbon rings and aromatic hydrocarbon rings. Heterocycles include aliphatic heterocycles and aromatic heterocycles. The ring formed by bonding adjacent groups to each other is a monocycle or polycycle. Furthermore, the ring formed by bonding to each other may be bonded to another ring to form a spiro structure.

[0032] As used herein, 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 sterically closest to the substituent. For example, two methyl groups in 1,2-dimethylbenzene are considered to be "adjacent groups" to each other, and two ethyl groups in 1,1-diethylcyclopentene are considered to be "adjacent groups" to each other.

[0033] In this specification, examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0034] In this specification, an alkyl group is straight-chain, branched-chain, or cyclic. The number of carbon atoms in the 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 ... Hexyl group, 2-butylhexyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-t-butylcyclohexyl group, n-heptyl group, 1-methylheptyl group, 2,2-dimethylheptyl group, 2-ethylheptyl group, 2-butylheptyl group, n-octyl group, t-octyl group, 2-ethyloctyl group, 2-butyloctyl group, 2-hexyloctyl group, 3,7-dimethyloctyl group, cyclooctyl group, n-nonyl group, n-decyl group, adamantyl group n-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.

[0035] In this specification, the hydrocarbon ring includes an aliphatic hydrocarbon ring and an aromatic hydrocarbon ring. The heterocycle includes an aliphatic heterocycle and an aromatic heterocycle. The hydrocarbon ring and the heterocycle may be monocyclic or polycyclic.

[0036] In this specification, the hydrocarbon ring group refers to any functional group or substituent derived from an aliphatic hydrocarbon ring, or any functional group or substituent derived from an aromatic hydrocarbon ring. The hydrocarbon ring group may have 5 to 60 ring carbon atoms. The hydrocarbon ring group may also be a saturated hydrocarbon ring group having 5 to 20 ring carbon atoms.

[0037] In this specification, a heterocyclic group refers to any functional group or substituent derived from a heterocycle containing at least one heteroatom as a ring-forming atom. The heterocyclic group contains one or more of B, O, N, P, Si, and S as the heteroatom. When a heterocyclic group contains two or more heteroatoms, the two or more heteroatoms may be the same or different. The heterocyclic group may be a monocyclic heterocyclic group or a polycyclic heterocyclic group, and is a concept that includes heteroaryl groups. The number of ring-forming carbon atoms of the heterocyclic group may be 2 to 60, for example, 2 to 30, 2 to 20, or 2 to 10.

[0038] As used herein, the term "aryl group" refers to any functional group or substituent derived from an aromatic hydrocarbon ring. The aryl group may be a monocyclic aryl group or a polycyclic aryl group. The number of ring carbon atoms in the aryl group may be 6 to 30, 6 to 20, or 6 to 15. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, fluorenyl, anthracenyl, phenanthryl, biphenylyl, terphenylyl, quaterphenylyl, quinquephenylyl, sexiphenylyl, triphenylenyl, pyrenyl, benzofluoranthenyl, and chrysenyl.

[0039] In this specification, the fluorenyl group may be substituted, and two substituents may be bonded to each other to form a spiro structure. Examples of fluorenyl groups that may be substituted include, but are not limited to, the following: [ka]

[0040] In this specification, the heteroaryl group contains one or more heteroatoms selected from B, O, N, P, Si, and S. When the heteroaryl group contains 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 in the heteroaryl group is 2 to 30, 2 to 20, or 2 to 10. Examples of heteroaryl groups include a thiophenyl group, a furanyl group, a pyrrolyl group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl 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 phenoxazinyl group, a phthalazinyl group, a pyridopyrimidinyl group, a pyridopyrazinyl group, a pyrazinopyrazinyl group, an isoquinolinyl group, and an indolyl group. , carbazolyl group, N-arylcarbazolyl group, N-heteroarylcarbazolyl group, N-alkylcarbazolyl group, benzoxazolyl group, benzimidazolyl group, benzothiazolyl group, benzocarbazolyl group, benzothiophenyl group, dibenzothiophenyl group, thienothiophenyl group, benzofuranyl group, phenanthrolinyl group, isoxazolyl group, thiadiazolyl group, phenothiazinyl group, dibenzosilolyl group, and dibenzofuranyl group, but are not limited to these.

[0041] As used herein, the term "silyl group" includes alkylsilyl groups and arylsilyl groups. Examples of silyl groups include, but are not limited to, trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, vinyldimethylsilyl, propyldimethylsilyl, triphenylsilyl, diphenylsilyl, and phenylsilyl groups.

[0042] As used herein, the term "boryl group" includes alkylboryl groups and arylboryl groups. Examples of boryl groups include, but are not limited to, trimethylboryl groups, triethylboryl groups, t-butyldimethylboryl groups, triphenylboryl groups, diphenylboryl groups, and phenylboryl groups.

[0043] In this specification, the number of carbon atoms in the amino group is not particularly limited, but is from 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.

[0044] Hereinafter, an organic electroluminescent device according to an embodiment of the present invention and a polycyclic compound included therein according to an embodiment will be described with reference to the accompanying drawings.

[0045] 1 to 4 are cross-sectional views schematically illustrating an organic electroluminescent device according to one embodiment of the present invention. Referring to FIGS. 1 to 4, in an organic electroluminescent device 10 according to one embodiment, a first electrode EL1 and a second electrode EL2 are disposed opposite each other, and a plurality of organic layers are disposed between the first electrode EL1 and the second electrode EL2. The plurality of organic layers includes a hole transport region HTR, an emission layer EML, and an electron transport region ETR. That is, the organic electroluminescent device 10 according to one 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. A capping layer CPL may further be disposed on the second electrode EL2.

[0046] The organic electroluminescent device 10 according to an embodiment includes a polycyclic compound according to an embodiment described below in at least one of a plurality of organic layers disposed between the first electrode EL1 and the second electrode EL2. For example, the organic electroluminescent device 10 according to an embodiment includes a polycyclic compound according to an embodiment described below in the emission layer EML disposed between the first electrode EL1 and the second electrode EL2. However, the present invention is not limited thereto. The organic electroluminescent device 10 according to an embodiment may include a polycyclic compound according to an embodiment described below in at least one of the organic layers included in the hole transport region HTR and the electron transport region ETR, which are the plurality of organic layers disposed between the first electrode EL1 and the second electrode EL2, in addition to the emission layer EML. Alternatively, the organic electroluminescent device 10 according to an embodiment may include a polycyclic compound according to an embodiment described below in the capping layer CPL disposed on the second electrode EL2.

[0047] Fig. 2, unlike Fig. 1, 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. Fig. 3, unlike Fig. 1, 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. Fig. 4, unlike Fig. 2, 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.

[0048] In the following description of an organic electroluminescent device 10 according to one embodiment, a case where the emission layer EML contains a polycyclic compound according to one embodiment described below will be described as an example, but the embodiment of the present invention is not limited thereto, and the polycyclic compound according to one embodiment described below may be contained in the hole transport region HTR, the electron transport region ETR, or the capping layer CPL.

[0049] The first electrode EL1 is conductive. The first electrode EL1 is made of a metal alloy or a conductive compound. The first electrode EL1 is an anode. The first electrode EL1 is also 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), or ITZO (indium tin zinc oxide). 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 (e.g., an alloy of Ag and Mg). The first electrode EL1 may have a multi-layer structure including a reflective film or semi-transparent film made of the above-mentioned 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 to this. 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 is, for example, about 5 nm to about 150 nm.

[0051] The hole transport region HTR may have 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.

[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 stacked in order from the first electrode EL1, such as a hole injection layer HIL / hole transport layer HTL, a hole injection layer HIL / hole transport layer HTL / hole buffer layer, a hole injection layer HIL / hole buffer layer (not shown), a hole transport layer HTL / hole buffer layer (not shown), or a hole injection layer HIL / hole transport layer HTL / hole blocking layer, but this 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 formed from, 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]triphenylamino), 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 / dodecanediol), or a phthalocyanine compound such as phthalocyanine. may include 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), 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.

[0055] The hole transport layer HTL may be formed from, 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), or a tetraphenylamine derivative such as NPB (N,N'-di(naphthalen-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 is about 10 nm to about 1000 nm, for example, about 10 nm to about 500 nm. The thickness of the hole injection layer HIL is, for example, about 3 nm to about 100 nm, and the thickness of the hole transport layer HTL is about 3 nm to about 100 nm. For example, the thickness of the electron blocking layer EBL is about 1 nm to about 100 nm. When the thicknesses of the hole transport region HTR, hole injection layer HIL, hole transport layer HTL, and 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 generation material to improve conductivity. The charge generation material may be uniformly or non-uniformly dispersed in the hole transport region HTR. The charge generation material may be, 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. Examples of p-dopants 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.

[0058] As described above, the hole transport region HTR may further include 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 depending on the wavelength of light emitted from the emitting layer EML to increase light emission efficiency. The material contained in the hole buffer layer (not shown) may be the same material as that contained in the hole transport region HTR. The electron blocking layer EBL is a layer that serves to prevent electrons from being injected from the electron transport region ETR to the hole transport region HTR.

[0059] The emitting layer EML is provided on the hole transport region HTR. The emitting layer EML has a thickness of, for example, about 10 nm to 100 nm, and may have a thickness of about 10 nm to about 30 nm. The emitting layer EML has a single layer made of a single material, a single layer made of multiple different materials, or a multilayer structure having multiple layers made of multiple different materials.

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

[0061]

[0013] The polycyclic compound according to one embodiment includes a substituted or unsubstituted indolophenazinyl group, a substituted or unsubstituted indolophenoxazinyl group, or a substituted or unsubstituted indolophenazinyl group which is substituted or unsubstituted with an electron-donating substituent.

[0062] The polycyclic compound according to one embodiment is represented by the following chemical formula 1. [ka] ...(chemical formula 1)

[0063] In Chemical Formula 1, L is a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms. In one embodiment, L may be a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridinylene group, a substituted or unsubstituted triazinylene group, a substituted or unsubstituted benzoxazolylene group, a substituted or unsubstituted benzothiazolylene group, a substituted or unsubstituted benzimidazolylene group, a substituted or unsubstituted imidazopyridinylene group, a substituted or unsubstituted oxazolopyridinylene group, a substituted or unsubstituted thiazolopyridinylene group, a substituted or unsubstituted dibenzoborinylene group, or a substituted or unsubstituted dibenzoxaborinylene group.

[0064] In Chemical Formula 1, A is 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. In one embodiment, A may be a substituted or unsubstituted phenyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted benzoxazolyl group, a substituted or unsubstituted benzothiazolyl group, a substituted or unsubstituted benzimidazolyl group, a substituted or unsubstituted imidazopyridinyl group, a substituted or unsubstituted oxazolopyridinyl group, a substituted or unsubstituted thiazolopyridinyl group, a substituted or unsubstituted dibenzoxaborinyl group, or a substituted or unsubstituted dibenzoxaborinyl group. In one embodiment, A may be a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

[0065] In Chemical Formula 1, at least one of L and A contains an electron-accepting substituent. In one embodiment, L is a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms, and A may contain an electron-accepting substituent. In one embodiment, L contains an electron-accepting substituent, and A may be a substituted or unsubstituted carbazole group, a substituted or unsubstituted arylamino group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

[0066] In Chemical Formula 1, n is an integer of 0 to 3. In Chemical Formula 1, l is 1 or 2.

[0067] In Chemical Formula 1, D is an electron-donating substituent. D is represented by Chemical Formula 2 below. [ka] ...(chemical formula 2)

[0068] In Chemical Formula 2, X is O, S, NR1, or SiR2R3. In one embodiment, X is O, S, or NR1. When X is O, the polycyclic compound represented by Chemical Formula 1 includes an indolophenazinyl group as an electron-donating substituent. When X is NR1, the polycyclic compound represented by Chemical Formula 1 includes an indolophenazinyl group as an electron-donating substituent.

[0069] In Chemical Formula 2, Y1 to Y 11 are each independently N or CR. In one embodiment, Y1 to Y 11 In one embodiment, Y1 to Y 11 Any one of them may be N, and the rest may be CR4.

[0070] In Chemical Formula 2, R1 to R4 each independently represent a single bond, 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 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. R1 to R4 may also each independently bond to adjacent groups to form a ring. In one embodiment, R1 may be a substituted or unsubstituted methyl group or a substituted or unsubstituted phenyl group. In one embodiment, R4 may be a hydrogen atom. When there are multiple R4s, the multiple R4s may be different from each other or the same.

[0071] In Chemical Formula 2, any one of R1 to R4 is a site that is bonded to L in Chemical Formula 1. Therefore, among R1 to R4, the group that is bonded to L in Chemical Formula 1 is a single bond. In one embodiment, in the substituent structure represented by Chemical Formula 2, X may be NR1, and R1 may be a site that is bonded to L. In addition, in the substituent structure represented by Chemical Formula 2, Y2 or Y 10 may be CR4, where R4 is the moiety that is bonded to L in Formula 1.

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

[0073] In chemical formulas A-1 to A-3, W1 to W 12 are each independently N or CR 13 In chemical formula A-1, W1 to W4 are all CR 13 Also, W1 may be N, and W2 to W4 may be CR. 13 In Chemical Formula A-2, W5 to W 12 are all CR 13 may be.

[0074] In formula A-1, Z1 is O or S. When Z1 is O, the substituent represented by formula A-1 contains a benzoxazole moiety. When Z1 is S, the substituent represented by formula A-1 contains a benzothiazole moiety.

[0075] In chemical formula A-2, Z2 is O, S, or NR 14 , C.R. 15 R 16 , or SiR 17 R 18 In one embodiment, Z2 is O, or CR 15 R 16 When Z2 is O, the substituent represented by formula A-2 contains a dibenzoxaborinyl moiety. 15 R 16 then the substituent represented by formula A-2 contains a dibenzoborinyl moiety.

[0076] In the chemical formula A-2, m is 0 or 1. When m is 0, Z2 does not exist in the substituent represented by the chemical formula A-2, and two 6-membered aromatic rings are substituted on the boron atom. In one embodiment, m is 0 and W5 to W 12 Both are CR 13 then the substituent represented by formula A-2 contains a diphenylborane moiety.

[0077] In Chemical Formula A-1 to Chemical Formula A-3, R5 to R 18 are each independently a single bond, 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. In one embodiment, R5 and R6 may both be a hydrogen atom.

[0078] In chemical formula A-3, R7 to R 12 At least one of R to R is a halogen atom or a cyano group. 12 One or two of R7 to R8 are cyano groups. 12 Each of R to R may be a halogen atom. 12 may each be a fluorine atom.

[0079] In Chemical Formula A-1 to Chemical Formula A-4, R5 to R 18 Any one of R5 to R6 is a bonded site to L in Chemical Formula 1. 18 Among these, the group bonded to L in Chemical Formula 1 is a single bond.

[0080] In Chemical Formula 1, A may be represented by any one of Chemical Formulas A-1-1 to A-3-3 below. [ka] ...(Chemical formula A-1-1) [ka] ...(Chemical formula A-1-2) [ka] ...(Chemical formula A-2-1) [ka] ...(Chemical formula A-2-2) [ka] ...(Chemical formula A-3-1) [ka] ...(Chemical formula A-3-2) [ka] ...(Chemical formula A-3-3)

[0081] In chemical formulas A-1-1 to A-3-3, W1 to W 12 , Z1, Z2, m, R5~R 18 The same applies to the above-described chemical formulas A-1 to A-3.

[0082] In Chemical Formula 1, D may be represented by the following Chemical Formula 2-1 or Chemical Formula 2-5. [ka] ...(chemical formula 2-1) [ka] ...(Chemical formula 2-2) [ka] ...(Chemical formula 2-3) [ka] ...(Chemical formula 2-4) [ka] ...(chemical formula 2-5)

[0083] In Chemical Formula 2-1 to Chemical Formula 2-5, Y1 to Y 11 The same applies to R1 to R4 as explained above in relation to Chemical Formula 2.

[0084] The polycyclic compound represented by Chemical Formula 1 is represented by Chemical Formula 3 below. [ka] ...(chemical formula 3)

[0085] In Chemical Formula 3, L1 and L2 are each independently a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms. In one embodiment, L1 and L2 are each independently a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridinylene group, a substituted or unsubstituted triazinylene group, a substituted or unsubstituted benzoxazolylene group, a substituted or unsubstituted benzothiazolylene group, a substituted or unsubstituted benzimidazolylene group, a substituted or unsubstituted imidazopyridinylene group, a substituted or unsubstituted oxazolopyridinylene group, a substituted or unsubstituted thiazolopyridinylene group, a substituted or unsubstituted dibenzoborinylene group, or a substituted or unsubstituted dibenzoxaborinylene group. In Chemical Formula 3, the same description as given above for L in Chemical Formula 1 applies to L1 to L2.

[0086] In Chemical Formula 3, D1 is an electron-donating substituent. D1 is represented by the above-mentioned Chemical Formula 2. In Chemical Formula 3, the same description as for D in the above-mentioned Chemical Formula 1 applies to D1.

[0087] In Chemical Formula 3, D2 is an electron-donating substituent, for example, D2 is a substituted or unsubstituted arylamino group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

[0088] In Chemical Formula 3, D1 and D2 are different from each other. In one embodiment, D1 is a substituted or unsubstituted indolophenazinyl group, and D2 may be a substituted or unsubstituted arylamino group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group. In one embodiment, D1 is a substituted or unsubstituted indolophenoxazinyl group, and D2 may be a substituted or unsubstituted arylamino group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

[0089] The polycyclic compound according to an embodiment may be any one of the compounds shown in the following first and second compound groups. The organic electroluminescent device 10 according to an embodiment includes at least one polycyclic compound selected from the compounds shown in the first and second compound groups in the emission layer EML. [First compound group] [ka] [ka] [ka] [ka]

[0090] [Second compound group] [ka] [ka] [ka] [ka]

[0091] The polycyclic compound represented by Chemical Formula 1 according to one embodiment is a thermally activated delayed fluorescent material. The polycyclic compound represented by Chemical Formula 1 according to one embodiment has a difference (ΔE ST For example, the polycyclic compound according to one embodiment represented by Chemical Formula 1 has a ΔE ST may be 0.10 eV or less.

[0092] In the organic electroluminescent device 10 according to one embodiment, the emitting layer EML emits delayed fluorescence. For example, the emitting layer EML may emit thermally activated delayed fluorescence (TADF).

[0093] The compound represented by Chemical Formula 1 according to an embodiment is a D (donor)-A (acceptor) type delayed fluorescent dopant material. In the compound represented by Chemical Formula 1 according to an embodiment, the indolophenazine or indolophenoxazine moiety corresponds to an electron donor moiety, and the substituent moiety represented by "A" corresponds to an electron acceptor moiety. That is, the compound represented by Chemical Formula 1 according to an embodiment is a DA type thermally activated delayed fluorescent dopant.

[0094] Alternatively, the compound of one embodiment represented by Chemical Formula 1 is represented by Chemical Formula 3, which is a D(donor)-A(acceptor)-D(donor) type delayed fluorescent dopant material. In the compound of one embodiment represented by Chemical Formula 3, the substituent moieties represented by D1 and D2 correspond to electron donating moieties, and the substituent moiety represented by "A" corresponds to electron accepting moieties.

[0095] The light emitting layer EML of the organic electroluminescent device 10 emits red or green light, but the embodiment of the present invention is not limited thereto, and the light emitting layer EML may emit blue light.

[0096] The compound according to one embodiment is a novel compound containing an indolophenazine or indolophenoxazine moiety as an electron donor moiety, and is used as a thermally activated delayed fluorescent light-emitting material and an emitting layer material of an organic electroluminescent device to improve luminous efficiency. In particular, the compound according to one embodiment is used as an emitting material that emits light in the green or red wavelength region and exhibits excellent luminous efficiency.

[0097] Meanwhile, although not shown, the organic electroluminescent device 10 according to an embodiment may include multiple light-emitting layers. The multiple light-emitting layers may be sequentially stacked, and for example, the organic electroluminescent device 10 including multiple light-emitting layers may emit white light. The organic electroluminescent device 10 including multiple light-emitting layers is an organic electroluminescent device with a tandem structure. When the organic electroluminescent device 10 includes multiple light-emitting layers, at least one of the light-emitting layers EML includes the polycyclic compound according to the embodiment described above.

[0098] In one embodiment, the emitting layer EML includes a host and a dopant, and includes the above-described polycyclic compound as the dopant. For example, in organic electroluminescent device 10 according to one embodiment, the emitting layer EML includes a delayed fluorescent host and a delayed fluorescent dopant, and may include the above-described polycyclic compound as the delayed fluorescent dopant. The emitting layer EML includes at least one of the polycyclic compounds shown in the first compound group and the second compound group as the thermally activated delayed fluorescent dopant.

[0099] In one embodiment, the emitting layer EML is a delayed fluorescent emitting layer, and the emitting layer MEL may include a known host material and the above-described polycyclic compound. For example, in one embodiment, the polycyclic compound according to one embodiment may be used as a TADF dopant.

[0100] The host material of the emitting layer EML may be a known material, and is not particularly limited, but may include fluoranthene derivatives, pyrene derivatives, arylacetylene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, and chrysene derivatives. Preferred host materials for the emitting layer EML include pyrene derivatives, perylene derivatives, and anthracene derivatives. For example, an anthracene derivative represented by the following chemical formula 4 may be used as the host material for the emitting layer EML. [ka] ...(chemical formula 4)

[0101] In Chemical Formula 4, R 31 ~R 40 are 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. 31 ~R 40 may combine with adjacent groups to form a ring. 31 ~R 40 may be bonded to adjacent groups to form a saturated or unsaturated hydrocarbon ring.

[0102] In Chemical Formula 4, c and d each independently represent an integer of 0 or more and 5 or less.

[0103] Chemical Formula 4 may be represented by any one of Chemical Formulas 3-1 to 3-16 below. [ka] JPEG0007797095000049.jpg40163

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[0104] In one embodiment, the emissive layer EML contains a host material selected from the group consisting of Alq3 (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(N-phenylbenzimidazol-2-yl)benzene), TBADN (3-tert-butyl-9,10-di(naphth-2-yl)anthracene), DSA (distyrylarylene), CDBP (4,4'-bis(9-carbazolyl)-2,2'-dimethyl-biphenyl), MADN (2-methyl- 9,10-bis(naphthalen-2-yl)anthracene), DPEPO (bis[2-diphenylphosphinophenyl]etheroxide), CP1 (hexaphenylcyclotriphosphazene), UGH2 (1,4-bis(triphenylsilyl)benzene), DPSiO3 (hexaphenylcyclotrisiloxane), DPSiO4 (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 host material is not limited to these, and may also include known delayed fluorescent host materials in addition to the host materials presented.

[0105] The compound according to an embodiment of the present invention may be used as a host material in the emitting layer EML. When the compound according to an embodiment is used as a host material, a known dopant material may be used in addition to the compound according to an embodiment in the emitting layer EML.

[0106] In the organic electroluminescent device 10 according to the embodiment, the emitting layer EML may further include a known dopant material. In one embodiment, the emitting layer MEL may further include, as a dopant, 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, etc.).

[0107] In one embodiment, the emitting layer EML may include two dopant materials having different lowest triplet excitation energy levels (T1 levels). In one embodiment of the organic electroluminescent device 10, the emitting layer EML may include a host having a first lowest triplet excitation energy level, a first dopant having a second lowest triplet excitation energy level lower than the first lowest triplet excitation energy level, and a second dopant having a third lowest triplet excitation energy level lower than the second lowest triplet excitation energy level. In one embodiment, the emitting layer EML includes the polycyclic compound according to one embodiment described above as the first dopant.

[0108] In an embodiment of the organic electroluminescent device 10, the emission layer EML includes a host, a first dopant, and a second dopant, the first dopant is a delayed fluorescent dopant, and the second dopant is a fluorescent dopant. In addition, in the organic electroluminescent device 10, the polycyclic compound represented by Chemical Formula 1 serves as an assistant dopant.

[0109] For example, when the emission layer EML of the organic electroluminescent device 10 according to an embodiment includes multiple dopants, the emission layer EML may include the polycyclic compound according to an embodiment described above as a first dopant and the known dopant material described above as a second dopant. For example, when the emission layer EML emits blue light, the emission layer EML may further include, as a second dopant, any one selected from the group consisting of spiro-DPVBi, spiro-6P, DSB (distyrylbenzene), DSA (distyrylarylene), PFO (polyfluorene)-based polymers, and PPV (poly(p-phenylenevinylene))-based polymers. Furthermore, the second dopant may be a metal complex or an organometallic complex such as (4,6-F2ppy)2Irpic, or perylene and its derivatives.

[0110] Meanwhile, in an embodiment of the organic electroluminescent device 10 including the polycyclic compound according to the embodiment as a first dopant in the emitting layer EML, when the emitting layer EML emits green light or red light, the second dopant material used may be the known dopant described above, or a known green fluorescent dopant or a known red fluorescent dopant.

[0111] In the organic electroluminescent device 10 according to an embodiment, the emitting layer EML may be a phosphorescent emitting layer. In this case, for example, the polycyclic compound according to an embodiment may be contained in the emitting layer EML as a phosphorescent host material.

[0112] 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 is not limited to these.

[0113] 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.

[0114] 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 a single-layer structure consisting of an electron injection material and an electron transport material. The electron transport region ETR may also have a single-layer structure consisting of multiple different materials, or a structure stacked in order from the light-emitting layer EML, such as an electron transport layer ETL / electron injection layer EIL or a hole-blocking layer HBL / electron transport layer ETL / electron injection layer EIL, but is not limited to these. The thickness of the electron transport region ETR is, for example, about 10 nm to about 150 nm.

[0115] 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).

[0116] When the electron transport region ETR includes an electron transport layer ETL, the electron transport region ETR includes an anthracene-based compound. However, the electron transport region is not limited thereto, and examples thereof include Alq3 (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-phenylbenzimidazolyl-1-ylphenyl)-9,10-dinaphthylanthracene, TPBi (1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen (4,7-diphenyl-1,10-phenanthroline), TAZ (3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazine), and the like. The electron transport layer ETL may include an organic compound such as tetrahydrofuran (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), Bebq2 (beryllium bis(benzoquinolin-10-olato), ADN (9,10-di(naphthalen-2-yl)anthracene), and a mixture 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, sufficient electron transport properties can be obtained without a substantial increase in driving voltage.

[0117] When the electron transport region ETR includes an electron injection layer EIL, the electron transport region ETR may be made of, but is not limited to, metal halides such as LiF, NaCl, CsF, RbCl, RbI, or CuI; lanthanoid metals such as Yb; metal oxides such as LiO or BaO; or lithium quinolate (LiQ). The electron injection layer EIL may also be made of a mixture of an electron transport material and an insulating organometallic salt. The organometallic salt has an energy band gap of about 4 eV or more. For example, the organometallic salt may include 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 50 nm, for example, about 0.3 nm to about 30 nm. If 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.

[0118] The electron transport region ETR may include a hole-blocking layer HBL as described above. The hole-blocking layer HBL may include, for example, but is not limited to, at least one of BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and Bphen (4,7-diphenyl-1,10-phenanthroline).

[0119] The second electrode EL2 is provided on the electron transport region ETR. The second electrode EL2 is a common electrode or a negative electrode. The second electrode EL2 may be 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, IZO, ZnO, or ITZO.

[0120] 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, an alloy of Ag and Mg). Alternatively, the second electrode EL2 may have a multi-layer structure including a reflective film or semi-transmissive film made of the above-mentioned materials and a transparent conductive film made of ITO, IZO, ZnO, ITZO, or the like.

[0121] Although not shown, the second electrode EL2 is connected to an auxiliary electrode, which can reduce the resistance of the second electrode EL2.

[0122] Meanwhile, 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, Alq, CuPc, TPD15 (N,N,N',N'-tetra(biphenyl-4-yl)biphenyl-4,4'-diamine), TCTA (4,4',4"-tris(carbazolesol-9-yl)triphenylamine), N,N'-bis(naphthalen-1-yl), or the like.

[0123] The organic electroluminescent device 10 according to an embodiment of the present invention exhibits high luminous efficiency by including the polycyclic compound according to an embodiment described above in the emitting layer EML disposed between the first electrode EL1 and the second electrode EL2. In addition, the polycyclic compound according to an embodiment is a thermally activated delayed fluorescence dopant, and the emitting layer EML includes the polycyclic compound according to an embodiment and emits thermally activated delayed fluorescence, thereby exhibiting high luminous efficiency.

[0124] Meanwhile, the polycyclic compound according to the embodiment described above may be included in an organic layer other than the emitting 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 polycyclic compound described above in at least one organic layer disposed between the first electrode EL1 and the second electrode EL2, or in the capping layer CPL disposed on the second electrode EL2.

[0125] The polycyclic compound according to the embodiment described above has a novel structure including an indolophenazine or indolophenoxazine moiety as an electron donor, which reduces the difference (ΔEst) between the lowest triplet excitation energy level (T1 level) and the lowest singlet excitation energy level (S1 level) compared to conventional compounds, thereby further improving the efficiency of organic electroluminescent devices when used as materials for the devices. [Example]

[0126] 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 more detail with reference to specific examples and comparative examples. The following examples are merely illustrative examples to aid in understanding the present invention, and the scope of the present invention is not limited thereto.

[0127] 1. Synthesis of polycyclic compounds First, the method for synthesizing polycyclic compounds according to the present embodiment will be specifically described by exemplifying the methods for synthesizing Compound 4, Compound 5, Compound 6, Compound 10, Compound 11, Compound 38, Compound 72, and Compound 77. The method for synthesizing polycyclic compounds described below is merely an example, and the method for synthesizing polycyclic compounds according to the present embodiment is not limited to the following example.

[0128] (1) Synthesis of Compound 4 Polycyclic compound 4 according to one embodiment can be synthesized, for example, according to the following reaction scheme 1. [Reaction Scheme 1] [ka]

[0129] (Synthesis of intermediate (1)) A 2000 mL single-neck flask was charged with 40.0 g (360.0 mmol) of 2-fluoroaniline, 106.9 g (378.0 mmol) of 2-bromoiodobenzene, and 1200 mL of toluene. 6.2 g (10.8 mmol) of Pd(dba)2 and NaO t After adding 69.2 g (719.9 mmol) of Bu and 11.97 g (21.6 mmol) of DPPF, the mixture was stirred at 100° C. for 3 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered through Celite using dichloromethane. The solvent was removed by vacuum distillation, and the mixture was purified using SiO column chromatography (DCM:Hexane=1:5) to obtain 81.7 g (yield: 85.3%) of an orange liquid compound (intermediate (1)).

[0130] (Synthesis of intermediate (2)) A 3000 mL two-neck flask was charged with 81.7 g (307.02 mmol) of intermediate (1) and 1535 mL of DMAc. 6.9 g (30.7 mmol) of Pd(OAc)2, 89.1 g (644.7 mmol) of K2CO3, and 22.6 g (61.4 mmol) of tricyclohexylphosphine tetrafluoroborate were added and stirred at 150 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered through Celite using dichloromethane. The solvent was removed by vacuum distillation and purified using SiO2 column chromatography (DCM:Hexane = 1:5). The resulting compound was subjected to a slurry process using dichloromethane and hexane to obtain 41.6 g (73.1% yield) of a light pink solid compound (intermediate (2)).

[0131] (Synthesis of intermediate (3)) A 2000 mL single-neck flask was charged with 25.0 g (135.0 mmol) of intermediate (2), 22.9 g (162.0 mmol) of 2-fluoronitrobenzene, and 540 mL of DMF. Then, 88.0 g (270.0 mmol) of Cs2CO3 was added and stirred at 100 °C for one day. After the reaction was completed, the mixture was cooled to room temperature and filtered through Celite using 500 mL of dichloromethane. The solvent was removed by vacuum distillation and purified using SiO2 column chromatography (DCM:Hexane = 1:2). The resulting compound was subjected to a slurry process using dichloromethane and hexane to obtain 34.6 g (83.8% yield) of a yellow solid compound (intermediate (3)).

[0132] (Synthesis of intermediate (4)) A 2000 mL single-neck flask was charged with 34.6 g (113.0 mmol) of intermediate (3) and 565 mL of ethanol, followed by the addition of 75.0 g (395.4 mmol) of SnCl2 and stirring at 85 °C for 30 minutes. After the reaction was completed, the mixture was cooled to room temperature and basified with 500 mL of 20% aqueous NaOH solution. Ethyl acetate was then added and the mixture was stirred at room temperature for 1 hour. The precipitated inorganic matter was removed by filtration through Celite. The filtered solution was extracted with ethyl acetate, and the water was removed using anhydrous magnesium sulfate. The solvent was then removed by vacuum distillation, and the mixture was purified using SiO2 column chromatography (DCM:Hexane = 1:1). The resulting compound was subjected to a slurry process using dichloromethane and hexane to obtain 25.5 g (81.6% yield) of a light orange solid compound (intermediate (4)).

[0133] (Synthesis of intermediate (5)) A 250 mL single-neck flask was charged with 2.0 g (7.2 mmol) of 2-(4-bromophenyl)benzoxazole, 2.0 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The resulting solid was subjected to a slurry process using dichloromethane and methanol to obtain 1.7 g (50.8% yield) of the ivory-colored compound (intermediate (5)).

[0134] (Synthesis of Compound 4) 3.7 g (7.9 mmol) of intermediate (5) and 78 mL of DMF were added to a 250 mL single-neck flask and stirred at room temperature. 1.3 g (11.8 mmol) of NaOtBu was added and stirred at 100 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 3.1 g (yield: 88.4%) of compound 4 as a yellow solid. FAB-MS analysis determined that the molecular weight of compound 4 was 450. Based on this result, the obtained compound was confirmed to be compound 4.

[0135] (2) Synthesis of Compound 5 Polycyclic compound 5 according to one embodiment can be synthesized, for example, according to the following reaction scheme 2. [Reaction Scheme 2] [ka]

[0136] (Synthesis of intermediate (6)) A 250 mL single-neck flask was charged with 1.97 g (7.2 mmol) of 2-(5-bromopyridin-2-yl)benzoxazole, 2.0 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 1.52 g (yield: 45.5%) of an ivory-colored solid compound (intermediate (6)).

[0137] (Synthesis of Compound 5) 3.5 g (7.4 mmol) of intermediate (6) and 78 mL of DMF were added to a 250 mL single-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO2 column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 2.5 g (yield: 76.4%) of compound 5 as a yellow solid. The molecular weight of compound 5 determined by FAB-MS analysis was 451. Based on this result, the obtained compound was confirmed to be compound 5.

[0138] (3) Synthesis of Compound 6 Polycyclic compound 6 according to one embodiment is synthesized, for example, according to the following reaction scheme 3. [Reaction Scheme 3] [ka]

[0139] (Synthesis of intermediate (7)) A 250 mL single-neck flask was charged with 1.97 g (7.2 mmol) of 2-(4-bromophenyl)benzo[d]oxazole-6-carbonitrile, 2.15 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 1.85 g (yield: 51.9%) of an ivory-colored solid compound (intermediate (7)).

[0140] (Synthesis of Compound 6) 3.3 g (7.0 mmol) of intermediate (7) and 78 mL of DMF were added to a 250 mL one-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO2 column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 2.3 g (yield: 70.2%) of compound 6 as a yellow solid. The molecular weight of compound 6 determined by FAB-MS analysis was 475. Based on this result, the obtained compound was confirmed to be compound 6.

[0141] (4) Synthesis of Compound 10 Compound 10 according to one embodiment is synthesized, for example, according to the following reaction scheme 4. [Reaction Scheme 4] [ka]

[0142] (Synthesis of intermediate (8)) 20.0 g (181.6 mmol) of 2-aminopyridin-3-ol and 45.1 g (181.6 mmol) of 4-iodobenzoic acid were thoroughly dissolved in a 500 mL single-neck flask, and then 140 mL of POCl3 was slowly added at 0°C and stirred. The mixture was heated to 90°C and reacted for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and slowly added dropwise to ice. After neutralization with sodium carbonate solution, the formed solid was filtered, washed with water and methanol, and dried to obtain 43.0 g (yield: 73.5%) of a white solid compound (intermediate (8)).

[0143] (Synthesis of intermediate (9)) A 250 mL two-neck flask was charged with 3.5 g (12.6 mmol) of intermediate (4), 4.1 g (12.6 mmol) of intermediate (8), 1.4 g (2.5 mmol) of Pd(dba)2, 2.4 g (5.1 mmol) of X-Phos, 8.3 g (25.3 mmol) of Cs2CO3, and 40 mL of xylene, and the mixture was refluxed and stirred for 26 hours. After confirming the completion of the reaction, the mixture was cooled to room temperature, filtered, and washed with ethyl acetate. The filtrate was extracted with purified water, and the organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The mixture was purified by silica gel column chromatography (Hex:EA=2:1). The resulting solid was added to dichloromethane and hexane, stirred for 1 hour, and then filtered to obtain 2.4 g (40.4% yield) of a yellow solid compound (intermediate (9)).

[0144] (Synthesis of Compound 10) A 250 mL two-neck flask was charged with 2.2 g (4.7 mmol) of intermediate (9), 0.8 g (7.1 mmol) of KOtBu, and 50 mL of DMF and stirred at 110°C for 5 hours. After confirming the completion of the reaction, the mixture was cooled to room temperature, and then 50 mL of distilled water was added and filtered. The solid was purified by silica gel column chromatography (Hex:EA:MC=1:1:2). Dichloromethane and hexane were added to the resulting solid, and the mixture was stirred for 1 hour and then filtered to obtain 0.7 g (35.6% yield) of compound 10 as a yellow solid. The molecular weight of compound 10 determined by FAB-MS analysis was 451. Based on this result, the resulting compound was confirmed to be compound 10.

[0145] (5) Synthesis of Compound 11 Compound 11 according to one embodiment can be synthesized, for example, according to the following reaction scheme 5. [Reaction Scheme 5] [ka]

[0146] (Synthesis of intermediate (10)) A 250 mL single-neck flask was charged with 1.97 g (7.2 mmol) of 2-(5-bromopyridin-2-yl)benzoxazole, 2.15 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 0.90 g (yield: 26.6%) of an ivory-colored solid compound (intermediate (10)).

[0147] (Synthesis of Compound 11) 3.3 g (7.0 mmol) of intermediate (10) and 78 mL of DMF were added to a 250 mL one-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO2 column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 1.4 g (yield: 44.7%) of compound 11 as a yellow solid. The molecular weight of compound 11 determined by FAB-MS analysis was 452. Based on this result, the obtained compound was confirmed to be compound 11.

[0148] (6) Synthesis of Compound 38 Polycyclic compound 38 according to one embodiment is synthesized, for example, according to the following reaction scheme 6. [Reaction Scheme 6] [ka]

[0149] (Synthesis of intermediate (11)) A 250 mL single-neck flask was charged with 2.6 g (7.2 mmol) of 2-(4-chlorophenyl)dimesitylborane, 2.15 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 2.68 g (yield: 61.9%) of the compound intermediate (11) as an ivory solid.

[0150] (Synthesis of Compound 38) 4.2 g (7.0 mmol) of intermediate (11) and 78 mL of DMF were added to a 250 mL one-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 0.74 g (yield: 18.3%) of compound 38 as a yellow solid. The molecular weight of compound 38 determined by FAB-MS analysis was 581. Based on this result, the obtained compound was confirmed to be compound 38.

[0151] (7) Synthesis of Compound 72 Polycyclic compound 27 according to one embodiment is synthesized, for example, according to the following reaction scheme 7. [Reaction Scheme 7] [ka]

[0152] (Synthesis of intermediate (12)) A 250 mL single-neck flask was charged with 3.3 g (7.2 mmol) of 10-(4-bromobenzo[d]oxazol-2-yl)phenyl)-10H-phenoxazine, 2.15 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 2.85 g (yield: 60.8%) of intermediate compound (12) as an ivory solid.

[0153] (Synthesis of Compound 72) 4.6 g (7.0 mmol) of intermediate (12) and 78 mL of DMF were added to a 250 mL one-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO2 column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 2.21 g (yield: 50.1%) of compound 72 as a yellow solid. The molecular weight of compound 72 determined by FAB-MS analysis was 631. Based on this result, the obtained compound was confirmed to be compound 72.

[0154] (8) Synthesis of Compound 77 Polycyclic compound 77 according to one embodiment is synthesized, for example, according to the following reaction scheme 8. [Reaction Scheme 8] [ka]

[0155] (Synthesis of intermediate (13)) A 250 mL single-neck flask was charged with 4.36 g (7.2 mmol) of 9-(4-(6-bromobenzo[d]oxazol-2-yl)phenyl)-2-diphenylaminocarbazole, 2.15 g (7.2 mmol) of intermediate (4), and 28 mL of xylene. 0.4 g (0.7 mmol) of Pd(dba)2, 7.1 g (21.7 mmol) of Cs2CO3, and 0.7 g (1.5 mmol) of XPhos were added and stirred at 140 °C for 4 h. After the reaction was completed, the mixture was cooled to room temperature, 100 mL of distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a gray solid. The resulting solid was purified by SiO2 column chromatography (EA:HEX = 1:5). The obtained solid was subjected to a slurry process using dichloromethane and methanol, to obtain 3.88 g (yield: 67.2%) of intermediate compound (13) as an ivory solid.

[0156] (Synthesis of Compound 77) 5.6 g (7.0 mmol) of intermediate (13) and 78 mL of DMF were added to a 250 mL one-neck flask and stirred at room temperature. t After adding 1.3 g (11.8 mmol) of Bu, the mixture was stirred at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, distilled water was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was filtered under reduced pressure with distilled water and methanol to obtain a yellow solid. The resulting solid was dissolved in 200 mL of dichloromethane and purified by SiO2 column chromatography (DCM:HEX = 2:1). A slurry process was performed using dichloromethane and methanol to obtain 2.8 g (yield: 51.4%) of compound 77 as a yellow solid. The molecular weight of compound 77 determined by FAB-MS analysis was 782. Based on this result, the obtained compound was confirmed to be compound 77.

[0157] 2.Evaluation of energy levels of polycyclic compounds The structures of the example compounds and comparative example compounds used in Examples 1 to 8 and Comparative Examples 1 and 2 are as follows: [ka]

[0158] Table 1 below shows the lowest singlet excitation energy level (S1 level), lowest triplet excitation energy level (T1 level), and ΔE of Example Compounds 4, 5, 6, 10, 11, 38, 72, and 77, as well as Comparative Compounds C1 and C2. ST The energy level values ​​in Table 1 were calculated using the ab initio molecular orbital method. Specifically, Gaussian09 manufactured by Gaussian was used, and the calculations were performed using 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). [Table 1]

[0159] 3. Fabrication and evaluation of organic electroluminescent devices containing polycyclic compounds (Fabrication of Organic Electroluminescent Device) Organic electroluminescent devices of one embodiment containing the polycyclic compound of one embodiment in the light-emitting layer were fabricated by the following method. The polycyclic compounds of the example compounds described above, Compound 4, Compound 5, Compound 6, Compound 10, Compound 11, Compound 38, Compound 72, and Compound 77, were used as dopant materials in the light-emitting layer to fabricate organic electroluminescent devices of Examples 1 to 8. Comparative Examples 1 and 2 correspond to organic electroluminescent devices fabricated using Comparative Example Compound C1 and Comparative Example Compound C2 as dopant materials in the light-emitting layer.

[0160] First, the ITO-patterned glass substrate was washed with ultrapure water, ultrasonically cleaned, irradiated with UV light 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 the hole transport region.

[0161] Next, when forming the light-emitting layer, the compound of one embodiment or the comparative compound and CBP 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 present invention was mixed with mCBP and deposited in the examples, and the comparative compound was mixed with mCBP and deposited in the comparative examples.

[0162] 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 using Mg:Ag (10:1).

[0163] The hole transport region, the light emitting layer, the electron transport region, and the second electrode described above were formed using a vacuum deposition apparatus.

[0164] The structures of the compounds in the layers used in the fabrication of the device are as follows: [ka]

[0165] (Evaluation of organic electroluminescent device characteristics) Table 2 shows the evaluation results of the organic electroluminescent devices of Examples 1 to 8 and Comparative Examples 1 and 2.

[0166] In the characteristic evaluation of the examples and comparative examples shown in Table 2, the luminous efficiency and device life are shown by comparing the efficiency and life of each device when the luminous efficiency and device life of the device in Comparative Example 1 are set to 100%. [Table 2]

[0167] Referring to the results in Table 2, it can be seen that the examples of organic electroluminescent devices using the polycyclic compounds according to one embodiment of the present invention as light-emitting layer materials exhibit relatively high luminous efficiency and life span compared to the comparative examples.

[0168] In the case of the example compounds, they exhibit TADF characteristics by utilizing the multiple resonance phenomenon of polycyclic aromatic rings, but also contain an indolophenazine or indolophenoxazine partial structure as an electron donor, and have a structure in which the electron donor and electron acceptor are linked via a linker, resulting in a smaller ΔE than the comparative compounds C1 and C2. ST As a result, the organic electroluminescent devices of the examples exhibit improved luminous efficiency compared to the organic electroluminescent devices of the comparative examples. In particular, the organic electroluminescent devices of the examples achieve high luminous efficiency in the red light or green light wavelength region by using the polycyclic compound according to an embodiment as a material for the light-emitting layer.

[0169] Although the present invention has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or those with ordinary knowledge in the art that various modifications and variations of the present invention can be made without departing from the spirit and technical scope of the present invention as set forth in the claims below.

[0170] Therefore, the technical scope of the present invention should be determined by the claims, not by the contents described in the detailed description of the specification. [Explanation of symbols]

[0171] 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 second electrode facing the first electrode; a light-emitting layer disposed between the first electrode and the second electrode, the light-emitting layer including a polycyclic compound represented by the following Chemical Formula 1: The first electrode and the second electrode each independently include any one selected from the group consisting of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, In, Zn, and Sn, a compound of two or more selected from the group consisting of these, a mixture of two or more selected from the group consisting of these, or an oxide of one or more selected from the group consisting of these, the light-emitting layer emits delayed fluorescence, The light-emitting layer is a host having a first lowest triplet excited energy level; a first dopant having a second lowest triplet excited energy level lower than the first lowest triplet excited energy level; a second dopant having a third lowest triplet excited energy level lower than the second lowest triplet excited energy level; The first dopant comprises a polycyclic compound represented by Chemical Formula 1. 【Chemistry 1】 ...(chemical formula 1) (In the above Chemical Formula 1, L is a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms, A is represented by any one of the following chemical formulas A-1 to A-3: 【Chemistry 2】 ...(Chemical formula A-1) 【Transformation 3】 ...(Chemical formula A-2) 【Chemistry 4】 ...(Chemical formula A-3) In the chemical formulas A-1 to A-3, W １ ~W １２ are each independently N or CR １３ and Z １ is O or S, Z ２ is O, S, NR １４ , C.R. １５ R １６ , or SiR １７ R １８ and m is 0 or 1; R ５ ~R １８ are each independently a single bond, 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 an unsubstituted heteroaryl group having from 2 to 30 ring carbon atoms; R ６ ~R １８ are bonded to adjacent groups to form a ring or are not bonded to adjacent groups, R ７ ~R １２ at least one of is a halogen atom or a cyano group, R ５ ~R １８ is a bond to L in Chemical Formula 1; R ７ ~R １２ When any of the formulas is a carbazolyl group, the 9-position of the carbazolyl group is bonded to the benzene ring, In the above Chemical Formula 1, at least one of L and A contains an electron-accepting substituent; n is an integer of 0 to 3, l is 1 or 2; D is represented by the following chemical formula 2: 【Transformation 5】 ...(chemical formula 2) In Chemical Formula 2, X is O, S, NR １ , or SiR ２ R ３ and Y １ ~Y １１ are each independently N or CR ４ and R １ ~R ４ are each independently a single bond, 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 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; R １ ~R ４ are bonded to adjacent groups to form a ring or are not bonded to adjacent groups, R １ ~R ４ Any one of these is a site that binds to L in Chemical Formula 1.

2. the first dopant is a delayed fluorescent dopant, The organic electroluminescent device according to claim 1 , wherein the second dopant is a fluorescent dopant.

3. a hole transport region disposed between the first electrode and the light-emitting layer; The organic electroluminescent device of claim 1 , further comprising an electron transport region disposed between the light-emitting layer and the second electrode.

4. The A is represented by any one of the following chemical formulas A-1-1 to A-3-3: The organic electroluminescent device according to claim 1 . 【Transformation 6】 ...(Chemical formula A-1-1) 【Transformation 7】 ...(Chemical formula A-1-2) 【Transformation 8】 ...(Chemical formula A-2-1) 【Chemistry 9】 ...(Chemical formula A-2-2) 【Chemistry 10】 ...(Chemical formula A-3-1) 【Chemistry 11】 ...(Chemical formula A-3-2) 【Chemistry 12】 ...(Chemical formula A-3-3)

5. The organic electroluminescent device according to claim 1 , wherein the polycyclic compound represented by Chemical Formula 1 is represented by Chemical Formula 3: 【Chemistry 13】 ...(chemical formula 3) (In the above Chemical Formula 3, L １ and L ２ are each independently a substituted or unsubstituted arylene group having from 6 to 30 ring carbon atoms or an unsubstituted heteroarylene group having from 2 to 30 ring carbon atoms; can be, D １ is represented by the above chemical formula 2, D ２ is an electron-donating substituent.

6. The above D ２ The organic electroluminescent device according to claim 5 , wherein is a substituted or unsubstituted arylamino group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted acridinyl group, or a substituted or unsubstituted phenoxazinyl group.

7. 2. The organic electroluminescent device according to claim 1, wherein D is represented by the following Chemical Formula 2-1 to Chemical Formula 2-5. 【Chemistry 14】 ...(Chemical formula 2-1) 【Chemistry 15】 ...(Chemical formula 2-2) 【Chemistry 16】 ...(Chemical formula 2-3) 【Chemistry 17】 ...(Chemical formula 2-4) [Chemistry 18] ...(Chemical formula 2-5)

8. 2. The organic electroluminescent device according to claim 1, wherein L is a substituted or unsubstituted phenylene group, a substituted or unsubstituted pyridinylene group, a substituted or unsubstituted triazinylene group, a substituted or unsubstituted benzoxazolylene group, a substituted or unsubstituted benzothiazolylene group, a substituted or unsubstituted benzimidazolylene group, a substituted or unsubstituted imidazopyridinylene group, a substituted or unsubstituted oxazolopyridinylene group, a substituted or unsubstituted thiazolopyridinylene group, a substituted or unsubstituted dibenzoborinylene group, or a substituted or unsubstituted dibenzoxaborinylene group.

9. A first electrode; a second electrode facing the first electrode; a light-emitting layer disposed between the first electrode and the second electrode, the light-emitting layer containing at least one polycyclic compound selected from the compounds shown in the following first compound group and second compound group, The first electrode and the second electrode each independently include any one selected from the group consisting of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, In, Zn, and Sn, a compound of two or more selected from the group consisting of these, a mixture of two or more selected from the group consisting of these, or an oxide of one or more selected from the group consisting of these, the light-emitting layer emits delayed fluorescence, The light-emitting layer is a host having a first lowest triplet excited energy level; a first dopant having a second lowest triplet excited energy level lower than the first lowest triplet excited energy level; a second dopant having a third lowest triplet excited energy level lower than the second lowest triplet excited energy level; The organic electroluminescent device, wherein the first dopant contains the polycyclic compound. [Compound Group 1] 【Chemistry 19】 【Chemistry 20】 【Chemistry 21】 【Chemistry 22】 [Group 2 of compounds] 【Chemistry 23】 【Chemistry 24】 【Chemistry 25】 【Chemistry 26】

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