Polycyclic aromatic compound

Abstract

To provide a novel compound suitable as a material for organic EL elements.SOLUTION: A polycyclic aromatic compound, represented by a formula (1), contains partial structures represented by a formula (X-a-1) and a formula (X-b-1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polycyclic aromatic compound, and to an organic device using the same, such as an organic electroluminescent element, an organic field effect transistor, and an organic thin-film solar cell, as well as a display device and a lighting device. [Background technology]

[0002] Conventionally, display devices using electroluminescent light-emitting elements have been extensively studied because they can be made to be energy-saving and thin, and organic electroluminescent elements made from organic materials have been actively studied because they can be easily made lighter and larger. In particular, there has been active research into the development of organic materials that have the luminescence properties of blue and green, which are one of the three primary colors of light, and organic materials that have the ability to transport charges such as holes and electrons (potential to become semiconductors or superconductors), regardless of whether they are polymer compounds or low molecular compounds.

[0003] An organic EL element has a structure consisting of a pair of electrodes consisting of an anode and a cathode, and one or more layers containing organic compounds that are disposed between the pair of electrodes. The layers containing organic compounds include a light-emitting layer and a charge transport / injection layer that transports or injects charges such as holes and electrons, and various organic materials suitable for these layers have been developed.

[0004] Currently, three types of luminescent materials are used for the luminescent layer: fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. For example, improved azaborine derivatives have been reported as fluorescent materials (Patent Documents 1 and 2), noble metal complexes with multidentate ligands have been developed as phosphorescent materials (Patent Document 3), and carbazonitrile compounds have been developed as thermally activated delayed fluorescence (TADF) materials (Non-Patent Document 1).

[0005] In devices using either material, a material with a high minimum excited singlet energy or minimum excited triplet energy is used in the layer adjacent to the light-emitting layer or as a host to prevent energy leakage from the light-emitting layer or surrounding layers that would lead to a decrease in efficiency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 102118 [Patent Document 2] International Publication No. 2018 / 212169 [Patent Document 3] JP 2014-239225 A [Non-patent literature]

[0007] [Non-Patent Document 1] Nature Vol.492 13 December 2012 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, various materials have been developed for use in organic EL devices, but in order to increase the options for materials for organic EL devices, it is desirable to develop materials made of compounds different from conventional ones. In addition, Patent Documents 1 and 2 report polycyclic aromatic compounds containing boron and organic EL devices using the same, but in order to further improve device characteristics, materials for light-emitting layers and materials for peripheral layers that can improve the light-emitting efficiency and device life are required. [Means for solving the problem]

[0009] As a result of intensive research to solve the above problems, the present inventors have succeeded in producing a novel polycyclic aromatic compound, and have found that this compound is effective as a material having high singlet energy and triplet energy.Then, for example, by using such a polycyclic aromatic compound as a host material or a material for a layer adjacent to an emitting layer, and disposing an emitting layer containing a compound having a smaller triplet energy as a dopant material between a pair of electrodes to construct an organic EL device, they have found that an excellent organic EL device can be obtained, and have completed the present invention.That is, the present invention provides the following polycyclic aromatic compounds, and further, materials for organic devices containing the following polycyclic aromatic compounds.

[0010] <1> A polycyclic aromatic compound represented by formula (1) and containing at least one partial structure represented by formula (Xa-1) and at least one partial structure represented by formula (Xb-1); [ka]

[0011] In formula (1), ring A, ring B, and ring C each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; In formula (Xa-1), X a represents C, Si, Ge, or Sn; the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; and the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring each may be linked to any of the other AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring via a single bond or a linking group; One or two selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 are is attached via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; It is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting a ring of an aryl ring or a heteroaryl ring of ring D, ring E, or ring AR5 in formula (Xb-1) which shares any ring with ring A, ring B, or ring C; Shares a ring with ring A, ring B, or ring C, or It is bonded to ring A, ring B, or ring C, or shares a ring with ring D, ring E, or ring AR5 in formula (Xb-1) which shares any ring with ring A, ring B, or ring C; In formula (Xb-1), ring D and ring E are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; X b is a divalent group represented by the formula (Xb-R5), >O, or >S, [ka] In formula (Xb-R5), The two #'s represent the bonding positions with the D and E rings, respectively. ring AR5 is a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and ring AR5 may be linked to ring D and / or ring E via a single bond or a linking group; One or two selected from the group consisting of D ring, E ring, and AR5 ring are is attached via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; It is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting an aryl ring or a heteroaryl ring in ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1) which shares any ring with ring A, ring B, or ring C; Shares a ring with ring A, ring B, or ring C, or It is bonded to ring A, ring B, or ring C, or shares a ring with ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1) which shares any ring with ring A, ring B, or ring C; In formula (1), at least one hydrogen may be replaced with a deuterium, and at least one nitrogen may be replaced with a nitrogen-15 ( 15 N), and at least one sulfur may be replaced by sulfur-33 ( 33 S), Sulfur-34( 34 S) or sulfur-36( 36 S), and at least one oxygen may be replaced by oxygen-17 ( 17 O) or oxygen-18( 18 O), and at least one carbon may be replaced by carbon-13 ( 13 C), and at least one boron may be replaced by boron-11 ( 11 B) may be substituted.

[0012] <2> At least one selected from the group consisting of AR1, AR2, AR3, and AR4 rings shares a ring with A, B, or C ring, or with D, E, or AR5 ring in formula (Xb-1) which is bonded to A, B, or C ring; <1> The polycyclic aromatic compound according to claim 1.

[0013] <3> Represented by formula (1a), formula (1b), or formula (1c), and including at least one partial structure represented by formula (Xa-2) and at least one partial structure represented by formula (Xb-2); <1> 4. A polycyclic aromatic compound according to claim 1 ; [ka]

[0014] In formula (1a), formula (1b), formula (1c), formula (Xa-2), and formula (Xb-2), Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4One or two selected from the group consisting of rings are is bonded to Z in ring a, ring b, or ring c through a single bond; It is bonded to ring d, ring e, or ring AR5 in the partial structure represented by formula (Xb-2) which is bonded to Z in ring a, ring b, or ring c, or Shares a ring with ring a, ring b, or ring c, or It is bonded to ring a, ring b, or ring c, or shares a ring with ring d, ring e, or ring AR5 in formula (Xb-2) which shares any ring with ring a, ring b, or ring c; One or two selected from the group consisting of d ring, e ring, and AR5 ring are is bonded to Z in ring a, ring b, or ring c through a single bond; Ar in the partial structure represented by formula (Xa-2) bonded to Z in ring a, ring b, or ring c 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 Attached to Z in the ring or Shares a ring with ring a, ring b, or ring c, or Ar in formula (Xa-2) is bonded to ring a, ring b, or ring c, or shares any ring with ring a, ring b, or ring c. 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 They share rings, Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 Each ring is another Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 may be linked to any one of the rings via a single bond or a linking group, Y 1 and Y 2 are each independently >NR NY ,>C(-R CY )2, >O, >Si(-RIY )2, >S, or >Se, and R NY , R CY , and R IY are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CY may be bonded to each other to form a ring, and two R IY may be bonded to each other to form a ring, Z is a carbon atom having a bond to another ring or -C(-R Z )= or -N=, and R Z is hydrogen or a substituent, provided that adjacent two of Z constituting the e ring in formula (Xb-2) may be carbon atoms bonded to two * in formula (Xb-2-e), and in formula (Xb-2-e), X b is a divalent group represented by the formula (Xb-R5), >O, >C(-R CX )2, >Si(-R IX )2, >S, or >Se, and R CX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CX may be bonded to each other to form a ring, R IX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; IX may be bonded to each other to form a ring, X b When is a divalent group represented by the formula (XB-R5), the AR5 ring is a six-membered ring.

[0015] <4> Represented by formula (1b) or formula (1c): <3> The polycyclic aromatic compound according to claim 1. <5> In formula (Xa-2), X ais C, Ge, or Sn, and any two of the Ar1 ring, the Ar2 ring, the Ar3 ring, and the Ar4 ring are not linked to each other; <3> The polycyclic aromatic compound according to claim 1. <6> In formula (Xa-2), X a is Si and at least one of Z is -N=; <3> The polycyclic aromatic compound according to claim 1. <7> In formula (Xa-2), X a is Si and Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 At least two of the rings are linked to each other; <3> The polycyclic aromatic compound according to claim 1. <8> In formula (Xb-2), at least one Z is -N=; <3> The polycyclic aromatic compound according to claim 1.

[0016] <9> Represented by one of the following formulas <3> The polycyclic aromatic compound according to claim 1. [ka]

[0017] [ka]

[0018] <10> Represented by one of the following formulas <3> The polycyclic aromatic compound according to claim 1. [ka]

[0019] [ka]

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] [ka]

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] <11> Represented by one of the following formulas <3> The polycyclic aromatic compound according to claim 1. [ka]

[0032] <12> The present invention has a pair of electrodes consisting of an anode and a cathode, and an organic layer disposed between the pair of electrodes, <1> ~ <11> 2. An organic electroluminescence device comprising the polycyclic aromatic compound according to claim 1. <13> The organic layer is an emitting layer. <12> The organic electroluminescent device according to claim 1. <14> the polycyclic aromatic compound is an electron transporting host material, and the light emitting layer further contains a hole transporting host material and a dopant material; <13> The organic electroluminescent device according to claim 1. <15> The light-emitting layer further comprises at least one selected from the group consisting of a thermally activated delayed fluorescent material and a phosphorescent material. <14> The organic electroluminescent device according to claim 1. <16> <11> ~ <15> A display device or a lighting device comprising the organic electroluminescent device according to any one of claims 1 to 4. Effect of the Invention

[0033] According to a preferred embodiment of the present invention, an organic EL device is produced using a novel polycyclic aromatic compound, for example, as a host material in an emitting layer, as a component of the host material, or as a component of a layer adjacent to the emitting layer, thereby providing an organic EL device having excellent quantum efficiency and device life. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an organic EL element according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment or a specific example, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "~" means a range including the numerical values ​​before and after "~" as the lower and upper limits. In this specification, "hydrogen" in the explanation of the structural formula means "hydrogen atom (H)". Similarly, when referring to an atom such as "carbon atom (C)", the "atom" may be omitted (for example, "carbon"). In this specification, the term "adjacent groups" refers to two groups bonded to two adjacent atoms (two atoms directly bonded by a covalent bond) in a structural formula.

[0036] In this specification, "Me" is methyl, "Et" is ethyl, "nBu" is n-butyl (normal butyl), "tBu" is t-butyl (tertiary butyl), "iBu" is isobutyl, "secBu" is secondary butyl, "nPr" is n-propyl (normal propyl), "iPr" is isopropyl, "tAm" is t-amyl, "2EH" is 2-ethylhexyl, "tOct" is t-octyl, "Ph" is phenyl, "Mes" is mesityl (2,4,6-trimethylphenyl), "Ad" is 1-adamantyl, "Tf" is trifluoromethanesulfonyl, "TMS" is trimethylsilyl, and "D" is deuterium. In this specification, the organic electroluminescent element may be referred to as an organic EL element.

[0037] In this specification, the chemical structure or the substituent may be expressed by the number of carbon atoms, but the number of carbon atoms in the case where a substituent is substituted on the chemical structure or where a substituent is further substituted on the substituent means the number of carbon atoms in each of the chemical structure and the substituent, and does not mean the total number of carbon atoms in the chemical structure and the substituent, or the total number of carbon atoms in the substituent and the substituent. For example, "substituent B of carbon number Y substituted with substituent A of carbon number X" means that "substituent B of carbon number Y" is substituted with "substituent A of carbon number X", and the carbon number Y is not the total number of carbon atoms in the substituent A and the substituent B. Also, for example, "substituent B of carbon number Y substituted with substituent A" means that "substituent B of carbon number Y" is substituted with "substituent A (without carbon number limit)", and the carbon number Y is not the total number of carbon atoms in the substituent A and the substituent B.

[0038] <Explanation of rings and substituents> First, the rings and substituents used in the present specification will be described in detail below. In the present specification, the "aryl ring" may, for example, be an aryl ring having 6 to 30 carbon atoms, preferably an aryl ring having 6 to 16 carbon atoms, more preferably an aryl ring having 6 to 12 carbon atoms, and particularly preferably an aryl ring having 6 to 10 carbon atoms.

[0039] Specific examples of the "aryl ring" include a monocyclic benzene ring, a bicyclic bicyclic bicyclic naphthalene ring, an indene ring, a tricyclic terphenyl ring (m-terphenyl, o-terphenyl, p-terphenyl), a condensed tricyclic acenaphthylene ring, a fluorene ring, a phenalene ring, a phenanthrene ring, an anthracene ring, a condensed tetracyclic triphenylene ring, a pyrene ring, a naphthacene ring, a chrysene ring, a condensed pentacyclic perylene ring, a pentacene ring, etc. In addition, the fluorene ring, the benzofluorene ring, and the indene ring each include a structure in which a fluorene ring, a benzofluorene ring, a cyclopentane ring, etc. are spiro-bonded. The fluorene ring, benzofluorene ring, and indene ring also include those in which two of the two hydrogen atoms of the methylene in the structure are replaced by alkyl such as methyl as the first substituent described below, resulting in a dimethylfluorene ring, dimethylbenzofluorene ring, dimethylindene ring, etc.

[0040] In the present specification, examples of the "heteroaryl ring" include heteroaryl rings having 2 to 30 carbon atoms, preferably heteroaryl rings having 2 to 25 carbon atoms, more preferably heteroaryl rings having 2 to 20 carbon atoms, further preferably heteroaryl rings having 2 to 15 carbon atoms, and particularly preferably heteroaryl rings having 2 to 10 carbon atoms. In addition, examples of the "heteroaryl ring" include heterocycles containing, as ring-constituting atoms other than carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, nitrogen, boron, selenium, phosphorus, and tellurium.

[0041] Specific examples of the "heteroaryl ring" include a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an oxadiazole ring (such as a furazan ring), a thiadiazole ring, a triazole ring, a tetrazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, an indole ring, an isoindole ring, a 1H-indazole ring, a benzimidazole ring, a benzoxazole ring, a benzothiazole ring, a 1H-benzotriazole ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, a phthalazine ring, a naphthyridine ring, a purine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenoxathiin ring, a phenoxazine ring, a phenothiazine ring, a phenazine ring, a phenazasiline ring, an indolizine ring, a furan ring, a benzofuran ring, an isobenzofuran ring, a dibenzofuran ring, and a thiophene ring. , benzothiophene ring, dibenzothiophene ring, thianthrene ring, indolocarbazole ring, benzoindolocarbazole ring, dibenzoindolocarbazole ring, naphthobenzofuran ring, dioxin ring, dihydroacridine ring, xanthene ring, thioxanthene ring, dibenzodioxin ring, dioxaboranaphthoanthracene ring (5,9-dioxa-13b-bora-13bH-naphtho[3,2,1-de]anthracene ring, etc.), benzoselenophene ring, Examples of the ring include a phenylene ring, a dibenzoselenophene ring, an azacarbazole ring, an azadibenzothiophene ring, an azadibenzofuran ring, an azadibenzoselenophene ring, an azatriphenylene ring, an imidazoimidazole ring, an indoloindole ring, a benzofurocarbazole ring, a benzothienocarbazole ring, an indenocarbazole ring, a selenophenocarbazole ring, a spiro[fluorene-9,9'-xanthene] ring, a spirobi[silafluorene] ring, etc. In addition, it is also preferable that the dihydroacridine ring, the xanthene ring, and the thioxanthene ring are such that two of the two hydrogen atoms of the methylene in the structure are replaced by alkyl such as methyl as the first substituent described later, to form a dimethyldihydroacridine ring, a dimethylxanthene ring, a dimethylthioxanthene ring, etc.In addition, bicyclic rings such as bipyridine ring, phenylpyridine ring, and pyridylphenyl ring, and tricyclic rings such as terpyridyl ring, bispyridylphenyl ring, and pyridylbiphenyl ring are also included as the "heteroaryl ring". The "heteroaryl ring" also includes a pyran ring.

[0042] In this specification, a substituent may be substituted with a further substituent. For example, a specific substituent may be described as "substituted or unsubstituted". This means that the specific substituent is substituted with at least one further substituent or is not substituted. In the same sense, the term "optionally substituted" may also be used. In this specification, the specific substituent may be referred to as a "first substituent" and the further substituent may be referred to as a "second substituent".

[0043] In this specification, the substituent group Zα consists of the substituents of the substituent group Z and the substituent represented by the formula (A30) described later.

[0044] In the present specification, the substituent group Z is an aryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen; heteroaryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen; diarylamino which may be substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two aryls may be bonded to each other via a linking group); diheteroarylamino optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two heteroaryls may be bonded to each other via a linking group); arylheteroarylamino which may be substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (aryl and heteroaryl may be bonded to each other via a linking group); diarylboryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two aryls may be bonded via a single bond or a linking group); an alkyl group optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, cycloalkyl, cyano, and halogen; cycloalkyl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen; alkoxy optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, cycloalkyl, cyano, and halogen; aryloxy optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen; Consists of substituted silyl, cyano, and halogen. The second substituent aryl in each group of the substituent group Z may be further substituted with an aryl, heteroaryl, alkyl, cycloalkyl, cyano, or halogen; similarly, the second substituent heteroaryl may be substituted with an aryl, heteroaryl, alkyl, cycloalkyl, cyano, or halogen.

[0045] In the present specification, when referring to a "substituent", the type of the substituent is not particularly limited, but unless otherwise specified, it may be any group selected from the substituent group Z. For example, when a group that is "substituted or unsubstituted" is substituted, the group may be substituted with at least one group selected from the substituent group Z.

[0046] In this specification, "aryl" is, for example, aryl having 6 to 30 carbon atoms, and preferably aryl having 6 to 20 carbon atoms, aryl having 6 to 16 carbon atoms, aryl having 6 to 12 carbon atoms, or aryl having 6 to 10 carbon atoms.

[0047] Specific examples of "aryl" include monovalent groups obtained by removing one hydrogen from the above-mentioned "aryl ring". For example, the monocyclic ring system phenyl, the bicyclic ring system biphenylyl (2-biphenylyl, 3-biphenylyl, or 4-biphenylyl), the fused bicyclic ring system naphthyl (1-naphthyl or 2-naphthyl), the tricyclic ring system terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, or p-terphenyl-4-yl), the fused tricyclic ring system acenaphthylene-(1-, 3-, 4-, or 5- -)yl, fluoren-(1-, 2-, 3-, 4-, or 9-)yl, phenalen-(1- or 2-)yl, phenanthrene-(1-, 2-, 3-, 4-, or 9-)yl, or anthracene-(1-, 2-, or 9-)yl, the tetracyclic ring system quaterphenylyl (5'-phenyl-m-terphenyl-2-yl, 5'-phenyl-m-terphenyl-3-yl, 5'-phenyl -m-terphenyl-4-yl, or m-quaterphenyl), fused tetracyclic ring systems such as triphenylene-(1- or 2-)yl, pyrene-(1-, 2-, or 4-)yl, or naphthacene-(1-, 2-, or 5-)yl, or fused pentacyclic ring systems such as perylene-(1-, 2-, or 3-)yl, or pentacene-(1-, 2-, 5-, or 6-)yl. Other examples include monovalent groups of spirofluorene.

[0048] The aryl as the second substituent also includes a structure in which the aryl is substituted with at least one group selected from the group consisting of aryl such as phenyl (specific examples are the groups described above), alkyl such as methyl (specific examples are the groups described below), and cycloalkyl such as cyclohexyl or adamantyl (specific examples are the groups described below). An example of such a group is a group in which the 9-position of fluorenyl as the second substituent is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl or adamantyl.

[0049] The "arylene" is, for example, an arylene having 6 to 30 carbon atoms, and preferably an arylene having 6 to 20 carbon atoms, an arylene having 6 to 16 carbon atoms, an arylene having 6 to 12 carbon atoms, or an arylene having 6 to 10 carbon atoms. Specific examples of "arylene" include divalent groups obtained by removing one hydrogen from the above-mentioned "aryl" (monovalent group).

[0050] The "heteroaryl" is, for example, a heteroaryl having 2 to 30 carbon atoms, and preferably a heteroaryl having 2 to 25 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, or a heteroaryl having 2 to 10 carbon atoms. The "heteroaryl" contains, as a ring-constituting atom other than carbon, one or more heteroatoms selected from oxygen, sulfur, nitrogen, etc., and preferably 1 to 5 heteroatoms.

[0051] Specific examples of the "heteroaryl" include monovalent groups obtained by removing one hydrogen atom from the above-mentioned "heteroaryl ring". For example, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, indolyl, isoindolyl, 1H-indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, 1H-benzotriazolyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, quinoxalinyl, phenanthrolinyl, phthalazinyl, naphthyridinyl, purinyl, pteridinyl, carbazolyl, acridinyl, phenoxathiinyl, phenoxazinyl, phenothiazinyl, phenazinyl, phenazasilinyl, indolizinyl, furanyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, naphthobenzofuranyl, thienyl, benzothienyl, isobenzothienyl, dibenzothienyl, naphthobenzothienyl, monovalent groups of benzophosphole oxide rings, monovalent groups of dibenzophosphole oxide rings, furazanyl, thianthrenyl, indolocarbazolyl, benzoindolocarbazolyl, dibenzoindolocarbazolyl, imidazolinyl, oxazolinyl, etc. Other examples include monovalent groups of spiro[fluorene-9,9'-xanthene], monovalent groups of spirobi[silafluorene], and monovalent groups of benzoselenophene.

[0052] The heteroaryl as the second substituent also includes a structure in which the heteroaryl is substituted with at least one group selected from the group consisting of aryl such as phenyl (specific examples are the groups described above), alkyl such as methyl (specific examples are the groups described below), and cycloalkyl such as cyclohexyl or adamantyl (specific examples are the groups described below). An example of such a group is a group in which the 9-position of the carbazolyl as the second substituent is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl or adamantyl. In addition, the heteroaryl as the second substituent also includes groups in which a nitrogen-containing heteroaryl such as pyridyl, pyrimidinyl, triazinyl, or carbazolyl is further substituted with phenyl or biphenylyl.

[0053] The "heteroarylene" is, for example, a heteroarylene having 2 to 30 carbon atoms, and preferably a heteroarylene having 2 to 25 carbon atoms, a heteroarylene having 2 to 20 carbon atoms, a heteroarylene having 2 to 15 carbon atoms, or a heteroarylene having 2 to 10 carbon atoms. In addition, the "heteroarylene" is, for example, a divalent group such as a heterocycle containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen as ring-constituting atoms. Specific examples of "heteroarylene" include divalent groups obtained by removing one hydrogen from the above-mentioned "heteroaryl" (monovalent group).

[0054] The term "diarylamino" refers to an amino substituted with two aryls, and the details of the aryls can be found in the above description of the "aryl". The term "diheteroarylamino" refers to an amino group substituted with two heteroaryls. For details of this heteroaryl, the above description of "heteroaryl" can be cited. The "arylheteroarylamino" is an amino group substituted with an aryl and a heteroaryl, and the details of the aryl and the heteroaryl can be found in the above descriptions of the "aryl" and the "heteroaryl".

[0055] The two aryls in the diarylamino as the first substituent may be bonded to each other via a linking group, the two heteroaryls in the diheteroarylamino as the first substituent may be bonded to each other via a linking group, and the aryl and heteroaryl in the arylheteroarylamino as the first substituent may be bonded to each other via a linking group. Here, the expression "bonded via a linking group" means that, for example, the two phenyls in diphenylamino form a bond with a linking group as shown below. This explanation also applies to diheteroarylamino and arylheteroarylamino formed by aryl and heteroaryl.

[0056] [ka]

[0057] Specific examples of the linking group include >O and >NR X ,>C(-R X )2, -C(-R X )=C(-R X )-, >Si(-R X )2, >S, >CO, >CS, >SO, >SO2, >SeO, >SeO2, >PO, >B(-R X ), and >Se. X are each independently an alkyl, cycloalkyl, aryl, or heteroaryl, which may be substituted with an alkyl, cycloalkyl, aryl, or heteroaryl. X )2, -C(-R X )=C(-R X )-, >Si(-R X )2 The two R X is a single bond or a linking group X Y They may be bonded to each other via X to form a ring. Y As for >O, >NR Y ,>C(-R Y )2, >Si(-R Y )2, >S, >CO, >CS, >SO, >SO2, and >Se, and R Yare each independently alkyl, cycloalkyl, aryl, or heteroaryl, which may be substituted with alkyl, cycloalkyl, aryl, or heteroaryl, provided that X Y >C(-R Y )2 and >Si(-R Y )2, two R Y does not bond to form a ring. Further examples of the linking group include alkenylene. Any hydrogen of the alkenylene is independently R 2X and R 2X are each independently an alkyl, a cycloalkyl, a substituted silyl, an aryl, or a heteroaryl, which may be substituted with an alkyl, a cycloalkyl, a substituted silyl, or an aryl. X )=C(-R X )- Two R's X may be bonded together to form an aryl ring (such as a benzene ring) or a heteroaryl ring together with the C=C to which they are attached. That is, -C(-R X )=C(-R X )- may be arylene (such as 1,2-phenylene) or heteroarylene.

[0058] In this specification, when "diarylamino", "diheteroarylamino", or "arylheteroarylamino" is simply described, unless otherwise specified, it is assumed that the following explanation is added: "the two aryls of the diarylamino may be bonded to each other via a linking group", "the two heteroaryls of the diheteroarylamino may be bonded to each other via a linking group", and "the aryl and heteroaryl of the arylheteroarylamino may be bonded to each other via a linking group", respectively.

[0059] "Diarylboryl" is a boryl substituted with two aryls, and the details of the aryls can be found in the above description of "aryl". The two aryls may be bonded via a single bond or a linking group (e.g., -CH=CH-, -CR=CR-, -C≡C-, >NR, >O, >S, >CO, >C=S, >S=O, >S(=O)2, >Se(=O), >Se(=O)2, >P(=O), >B(-R), >C(-R)2, >Si(-R)2, or >Se). Here, R of -CR=CR-, R of >NR, R of >B(-R), R of >C(-R)2, and R of >Si(-R) are aryl, heteroaryl, diarylamino, alkyl, alkenyl, alkynyl, cycloalkyl, alkoxy, or aryloxy, and at least one hydrogen in the R may be further substituted with aryl, heteroaryl, alkyl, alkenyl, alkynyl, or cycloalkyl. In addition, two adjacent R may be bonded to each other to form a ring, forming a cycloalkylene, arylene, or heteroarylene. For details of the substituents listed here, the explanations of "aryl", "arylene", "heteroaryl", "heteroarylene", and "diarylamino" above, and the explanations of "alkyl", "alkenyl", "alkynyl", "cycloalkyl", "cycloalkylene", "alkoxy", and "aryloxy" below can be cited. In addition, when the term "diarylboryl" is used simply in this specification, unless otherwise specified, it is assumed that the explanation that "the two aryls of the diarylboryl may be bonded to each other via a single bond or a linking group" is added.

[0060] The "alkyl" may be either straight chain or branched chain, for example, straight chain alkyl having 1 to 24 carbon atoms or branched chain alkyl having 3 to 24 carbon atoms, and preferably alkyl having 1 to 18 carbon atoms (branched chain alkyl having 3 to 18 carbon atoms), alkyl having 1 to 12 carbon atoms (branched chain alkyl having 3 to 12 carbon atoms), alkyl having 1 to 6 carbon atoms (branched chain alkyl having 3 to 6 carbon atoms), alkyl having 1 to 5 carbon atoms (branched chain alkyl having 3 to 5 carbon atoms), alkyl having 1 to 4 carbon atoms (branched chain alkyl having 3 to 4 carbon atoms), etc.

[0061] Specific examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl, 1,1,2,2-tetramethylpropyl, 1-ethyl-1,2,2-trimethylpropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-ethylbutyl, 1,1-dimethylbutyl, 3,3-dimethylbutyl, 1,1-diethylbutyl, 1-ethyl-1-methylbutyl, 1-propyl-1-methylbutyl, 1,1,3-trimethylbutyl, 1-ethyl-1,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, t-pentyl (t-amyl), 1-methylpentyl, 2-propylpentyl, 1,1-dimethylpentyl, 1-ethyl-1-methylpentyl, 1-propyl-1 -Methylpentyl, 1-butyl-1-methylpentyl, 1,1,4-trimethylpentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 1,1-dimethylhexyl, 1-ethyl-1-methylhexyl, 1,1,5-trimethylhexyl, 3,5,5-trimethylhexyl, n-heptyl, 1-methylheptyl, 1-hexylheptyl, 1,1-dimethylheptyl, 2,2-dimethylhexyl Examples of the alkyl groups include methylheptyl, 2,6-dimethyl-4-heptyl, n-octyl, t-octyl (1,1,3,3-tetramethylbutyl), 1,1-dimethyloctyl, n-nonyl, n-decyl, 1-methyldecyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl.

[0062] An "alkylene" is a divalent group obtained by removing any hydrogen from an "alkyl", such as methylene, ethylene, or propylene.

[0063] For "alkenyl", the explanation of "alkyl" above can be referred to, and it is a group in which a C--C single bond in the "alkyl" structure is replaced with a C=C double bond, and also includes groups in which not only one but two or more single bonds are replaced with double bonds (also called alkadiene-yl or alkatriene-yl).

[0064] "Alkenylene" is a divalent group obtained by removing any hydrogen from "alkenyl", and examples include vinylene.

[0065] For "alkynyl", the explanation of "alkyl" above can be referred to, and it is a group in which the C--C single bond in the "alkyl" structure is replaced with a C≡C triple bond, and also includes groups in which not only one but two or more single bonds are replaced with triple bonds (also called alkadiyn-yl or alkatriyn-yl).

[0066] The "cycloalkyl" is, for example, cycloalkyl having 3 to 24 carbon atoms, and preferably cycloalkyl having 3 to 20 carbon atoms, cycloalkyl having 3 to 16 carbon atoms, cycloalkyl having 3 to 14 carbon atoms, cycloalkyl having 3 to 12 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, cycloalkyl having 5 to 6 carbon atoms, or cycloalkyl having 5 carbon atoms.

[0067] Specific examples of "cycloalkyl" include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, or alkyl (particularly methyl) substituted derivatives of these having 1 to 5 or 1 to 4 carbon atoms, bicyclo[1.1.0]butyl, bicyclo[1.1.1]pentyl, bicyclo[2.1.0]pentyl, bicyclo[2.1.1]hexyl, bicyclo[3.1.0]hexyl, bicyclo[2.2.1]heptyl (norbornyl), bicyclo[2.2.2]octyl, adamantyl, diamantyl, decahydronaphthalenyl, and decahydroazulenyl.

[0068] "Cycloalkylene" is, for example, cycloalkylene having 3 to 24 carbon atoms, and preferably cycloalkylene having 3 to 20 carbon atoms, cycloalkylene having 3 to 16 carbon atoms, cycloalkylene having 3 to 14 carbon atoms, cycloalkylene having 3 to 12 carbon atoms, cycloalkylene having 5 to 10 carbon atoms, cycloalkylene having 5 to 8 carbon atoms, cycloalkylene having 5 to 6 carbon atoms, cycloalkylene having 5 carbon atoms, or the like. A specific example of the "cycloalkylene" is a structure in which one hydrogen is removed from the above-mentioned "cycloalkyl" (monovalent group) to form a divalent group.

[0069] "Cycloalkenyl" refers to a group having a structure in which at least one pair of single bonds between two carbons in the above-mentioned "cycloalkyl" is a double bond (for example, a group in which -CH2-CH2- is replaced with -CH=CH-), and does not fall under the category of aryl. Specific examples include 1-cyclohexenyl and 1-cyclopentenyl.

[0070] "Alkoxy" is a group represented by "Alk-O-(Alk is alkyl)". For details of the alkyl, the above explanation of "alkyl" can be cited.

[0071] "Aryloxy" is a group represented by "Ar-O-(Ar is aryl)", and the above explanation of "aryl" can be cited for details of the aryl.

[0072] The "substituted silyl" is, for example, a silyl substituted with at least one of an aryl, an alkyl, and a cycloalkyl, and is preferably a triarylsilyl, a trialkylsilyl, a tricycloalkylsilyl, a dialkylcycloalkylsilyl, or an alkyldicycloalkylsilyl.

[0073] The term "triarylsilyl" refers to a silyl group substituted with three aryl groups. For details of the aryl groups, see the above description of the "aryl". Specific "triarylsilyl" includes, for example, triphenylsilyl, diphenylmononaphthylsilyl, monophenyldinaphthylsilyl, trinaphthylsilyl, and the like.

[0074] The term "trialkylsilyl" refers to a silyl group substituted with three alkyl groups. For details of this alkyl, see the above description of "alkyl." Specific examples of "trialkylsilyl" include trimethylsilyl, triethylsilyl, tri-n-propylsilyl, triisopropylsilyl, tri-n-butylsilyl, triisobutylsilyl, tri-s-butylsilyl, tri-t-butylsilyl, ethyldimethylsilyl, n-propyldimethylsilyl, isopropyldimethylsilyl, n-butyldimethylsilyl, isobutyldimethylsilyl, s-butyldimethylsilyl, t-butyldimethylsilyl, methyldiethylsilyl, n-propyldiethylsilyl, isopropyldiethylsilyl, n-butyldiethylsilyl, s-butyldiethylsilyl, t-butyldiethylsilyl, methyldi-n-propylsilyl, ethyldi-n-propylsilyl, n-butyldi-n-propylsilyl, s-butyldi-n-propylsilyl, t-butyldi-n-propylsilyl, methyldiisopropylsilyl, ethyldiisopropylsilyl, n-butyldiisopropylsilyl, s-butyldiisopropylsilyl, and t-butyldiisopropylsilyl.

[0075] The term "tricycloalkylsilyl" refers to a silyl group substituted with three cycloalkyl groups. For details of this cycloalkyl, see the above description of "cycloalkyl." Specific "tricycloalkylsilyl" includes, for example, tricyclopentylsilyl or tricyclohexylsilyl.

[0076] The "dialkylcycloalkylsilyl" is a silyl group substituted with two alkyls and one cycloalkyl. For details of the alkyl and cycloalkyl, see the above descriptions of "alkyl" and "cycloalkyl".

[0077] The term "alkyldicycloalkylsilyl" refers to a silyl group substituted with one alkyl and two cycloalkyl. For details of the alkyl and cycloalkyl, see the above descriptions of "alkyl" and "cycloalkyl".

[0078] "Halogen" is fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine, more preferably fluorine or chlorine, even more preferably fluorine.

[0079] When cyano or halogen is substituted, embodiments in which all or a part of the hydrogen atoms in the aryl ring or heteroaryl ring in the structure are replaced with cyano or halogen are also preferred.

[0080] The substituent represented by formula (A30) has the following structure. [ka]

[0081] In formula (A30), Ak is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkyl, or substituted or unsubstituted cycloalkenyl, in which at least one -CH2- in the alkyl, cycloalkyl, and cycloalkenyl may be replaced by -O- or -S-; R Ak is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, or a substituted or unsubstituted cycloalkyl; R Ak may be bonded to Ak via a linking group or a single bond, and * indicates the bonding position.

[0082] In formula (A30), since Ak is the above-mentioned substituent, it does not conjugate with the unshared electron pair on N, so that the unshared electron pair can be conjugated with the π electron of the bonded destination, and a larger wavelength shift is possible compared to when an aryl or the like is present at the same position. The same applies to the influence on the multiple resonance effect, and a larger improvement in thermally activated delayed fluorescence (TADF) properties is possible.

[0083] R Ak is preferably aryl which may be substituted with alkyl or cycloalkyl, heteroaryl which may be substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, more preferably aryl which may be substituted with alkyl, heteroaryl which may be substituted with alkyl, alkyl or cycloalkyl, even more preferably aryl which may be substituted with alkyl, and particularly preferably phenyl which may be substituted with methyl.

[0084] In formula (A30), Ak is preferably an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 14 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably methyl.

[0085] R Ak and Ak may be the same or different, and are preferably different.

[0086] R Ak may be bonded to Ak via a linking group or a single bond. In this case, examples of the linking group include >O, >S, and >Si(-R)2. R in >Si(-R)2 is hydrogen, an aryl having 6 to 12 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms. R Ak Examples of the structure in which is bonded to Ak via a linking group or a single bond include the following.

[0087] [ka] In the above formulas, * indicates a bonding position.

[0088] <When two groups bonded to the same atom are bonded to each other> In the present specification, when it is stated that two groups bonded to the same atom may be bonded to each other to form a ring, they may be bonded by a single bond or a linking group (collectively also referred to as a linking group), and examples of the linking group include -CH2-CH2-, -CHR-CHR-, -CR2-CR2-, -CH=CH-, -CR=CR-, -C≡C-, -N(-R)-, -O-, -S-, -C(-R)2-, -C(=O)-, -C(=S)-, -S(=O)-, -S(=O)2-, -Se(=O)-, -Se(=O)2-, -P(=O)-, -B(-R)-, -Si(-R)2-, or -Se-, for example, the following structure. In addition, R of -CHR-CHR-, R of -CR2-CR2-, R of -CR=CR-, R of -N(-R)-, R of -C(-R)2-, R of -B(-R)-, and R of -Si(-R)2- are each independently hydrogen, aryl which may be substituted with alkyl or cycloalkyl, heteroaryl which may be substituted with alkyl or cycloalkyl, alkyl which may be substituted with cycloalkyl, alkenyl which may be substituted with alkyl or cycloalkyl, alkynyl which may be substituted with alkyl or cycloalkyl, or cycloalkyl which may be substituted with alkyl or cycloalkyl. In addition, two adjacent Rs may be bonded to each other to form a ring, forming a cycloalkylene, arylene, or heteroarylene.

[0089] [ka]

[0090] As the bonding group, a single bond and -CR=CR-, -N(-R)-, -O-, -S-, -C(-R)2-, -Si(-R)2-, and -Se- as linking groups are preferred, a single bond and -CR=CR-, -N(-R)-, -O-, -S-, and -C(-R)2- as linking groups are more preferred, a single bond and -CR=CR-, -N(-R)-, -O-, and -S- as linking groups are even more preferred, and a single bond is most preferred.

[0091] The position where two R are bonded by the bonding group is not particularly limited as long as it is a bondable position, but it is preferable that they are bonded at the most adjacent positions. For example, when the two groups are phenyl, it is preferable that they are bonded at the ortho (2nd) positions based on the bonding position (1st position) of "C" or "Si" in the phenyl (see the above structural formula).

[0092] <Stereoisomers, etc.> The polycyclic aromatic compound of the present invention may exist as an enantiomer or diastereomer depending on the type of substituents, etc., but regardless of the structural formula described, any stereoisomer in any pure form, any mixture of stereoisomers, racemates, etc. are all intended to be included within the scope of the present invention.

[0093] 1. Polycyclic aromatic compound of the present invention The polycyclic aromatic compound of the present invention is represented by formula (1) and contains at least one partial structure represented by formula (Xa-1) and at least one partial structure represented by formula (Xb-1). [ka]

[0094] In formula (1), ring A, ring B, and ring C each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; In formula (Xa-1), X arepresents C, Si, Ge, or Sn; ring AR1, ring AR2, ring AR3, and ring AR4 each independently represent a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl; and any two selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 may be linked to each other via a single bond or a linking group; One or two selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 are is attached via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; It is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting a ring of an aryl ring or a heteroaryl ring of ring D, ring E, or ring AR5 in formula (Xb-1) which shares any ring with ring A, ring B, or ring C; Shares a ring with ring A, ring B, or ring C, or It is bonded to ring A, ring B, or ring C, or shares a ring with ring D, ring E, or ring AR5 in formula (Xb-1) which shares any ring with ring A, ring B, or ring C; In formula (Xb-1), ring D and ring E are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; X b is a divalent group having an AR5 ring, >O, or >S, ring AR5 is a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl, and ring AR5 may be linked to ring D and / or ring E via a single bond or a linking group; One or two selected from the group consisting of D ring, E ring, and AR5 ring are is attached via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; It is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting an aryl ring or a heteroaryl ring in ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1) which shares any ring with ring A, ring B, or ring C; Shares a ring with ring A, ring B, or ring C, or It is bonded to ring A, ring B, or ring C, or shares a ring with ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1) which shares any ring with ring A, ring B, or ring C; At least one hydrogen in the structure may be replaced with deuterium.

[0095] The present inventors have found that the polycyclic aromatic compound of the present invention, in which aromatic rings are linked by oxygen, has a large HOMO-LUMO gap (band gap Eg in a thin film) and high triplet energy. This is believed to be because the ring containing a hetero element has low aromaticity, so that the decrease in the HOMO-LUMO gap accompanying the expansion of the conjugated system is suppressed, and a large HOMO-LUMO gap can be obtained by suppressing the expansion of the conjugated system by utilizing intramolecular distortion.

[0096] In addition, the hetero element-containing polycyclic aromatic compound according to the present invention is useful as a material having high triplet energy, as a host compound for phosphorescent organic EL devices and organic EL devices using thermally activated delayed fluorescence, as an electron blocking layer (electron blocking layer) or hole blocking layer (hole blocking layer) adjacent to the light-emitting layer, as an electron transport layer or hole transport layer. Furthermore, these polycyclic aromatic compounds can arbitrarily move the energies of HOMO and LUMO by introducing a substituent, so that the ionization potential and electron affinity can be optimized according to the surrounding materials.

[0097] <Explanation of ring structure in compound> In formula (1), "A", "B", and "C" in a circle are symbols that indicate a ring structure represented by a circle, in formula (Xa-1), "AR1", "AR2", "AR3", and "AR4" are symbols that indicate a ring structure represented by a circle, and in formula (Xb-1), "D" and "E" are symbols that indicate a ring structure represented by a circle. b In the formula, "AR5" is a code indicating a ring structure represented by a circle.

[0098] Ring A, ring B, ring C, ring D, ring E, ring AR1, ring AR2, ring AR3, ring AR4, and ring AR5 are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring.

[0099] The ring A forms a trivalent group having bonds to three consecutive atoms (preferably carbon) on the aryl or heteroaryl ring in the structure. The three bonds of the ring A bond to two O (oxygen) and B (boron). When the ring A is further bonded to the ring AR1, the ring AR2, the ring AR3, the ring AR4, the ring AR5, the ring D, or the ring E at another site as described below, or when the ring A shares an aryl or heteroaryl ring with the ring AR1, the ring AR2, the ring AR3, the ring AR4, the ring AR5, the ring D, or the ring E, the ring A may be a tetravalent or pentavalent group. In the ring A, the ring having the atom having the above bond as a ring-constituting atom is preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring. This ring may be further condensed with another ring. Examples of the 6-membered ring include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of 6-membered rings further condensed with other rings include a naphthalene ring, a quinoline ring, a dibenzofuran ring, a dibenzothiophene ring, and a carbazole ring. Examples of 5-membered rings include a furan ring, a thiophene ring, a pyrrole ring, and a thiazole ring. Examples of 5-membered rings further condensed with other rings include a benzofuran ring, a benzothiophene ring, and an indole ring. An example of a condensed ring is an indene ring. The aryl ring or heteroaryl ring in ring A is preferably a benzene ring.

[0100] Both ring B and ring C form a divalent group having bonds to two atoms (preferably carbon) adjacent to each other on the aryl or heteroaryl ring in the structure. Ring B is bonded to O (oxygen) and B (boron) with the above two bonds, and ring C is bonded to O (oxygen) and B (boron) with the above two bonds. When ring B and ring C are bonded to ring AR1, ring AR2, ring AR3, ring AR4, ring AR5, ring D, or ring E at another site as described below, or when ring B and ring C share an aryl or heteroaryl ring with ring AR1, ring AR2, ring AR3, ring AR4, ring AR5, ring D, or ring E, ring B and ring C may each be a trivalent or tetravalent group. In each of ring B and ring C, the ring having the above atoms having the two bonds as ring constituent atoms is preferably a 5-membered or 6-membered ring, more preferably a 6-membered ring. This ring may be further condensed with another ring. Examples of six-membered rings include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of six-membered rings further condensed with other rings include a naphthalene ring, a quinoline ring, a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, and a dibenzoselenophene ring. Examples of five-membered rings include a furan ring, a thiophene ring, a pyrrole ring, a thiazole ring, and a selenophene ring. Examples of five-membered rings further condensed with other rings include a benzofuran ring, a benzothiophene ring, an indole ring, and a benzoselenophene ring. An example of a condensed ring is an indene ring. The aryl ring or heteroaryl ring in ring B and ring C is preferably a benzene ring, a benzofuran ring, a benzothiophene ring, or a benzoselenophene ring, and more preferably a benzene ring, a benzofuran ring, or a benzothiophene ring.

[0101] Both ring D and ring E form a divalent group having bonds to two adjacent atoms (preferably carbon) on the aryl or heteroaryl ring in the structure. Ring D is connected to X by the above two bonds.b and E ring, and E ring is connected to X by the above two bonds. b and ring D. When ring D and ring E are each bonded to ring AR5 at a different site, ring D and ring E may each be a trivalent group. When ring D and ring E are each bonded to ring AR1, ring AR2, ring AR3, ring AR4, ring A, ring B, or ring C at a different site, as described below, or when ring D and ring E share an aryl ring or heteroaryl ring with ring AR1, ring AR2, ring AR3, ring AR4, ring A, ring B, or ring C, ring D and ring E may each be a trivalent or tetravalent group. In each of ring D and ring E, the ring having the above-mentioned two bond atoms as ring constituent atoms is preferably a 5-membered ring or a 6-membered ring, more preferably a 6-membered ring. This ring may be further condensed with another ring. Examples of the 6-membered ring include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of 6-membered rings further condensed with other rings include a naphthalene ring, a quinoline ring, a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, a dibenzoselenophene ring, etc. Examples of 5-membered rings include a furan ring, a thiophene ring, a pyrrole ring, a thiazole ring, a selenophene ring, etc. Examples of 5-membered rings further condensed with other rings include a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, etc. The aryl ring or heteroaryl ring in ring D and ring E is each independently preferably a benzene ring or a pyridine ring, more preferably a benzene ring.

[0102] Each of the AR1 ring, the AR2 ring, the AR3 ring, the AR4 ring, and the AR5 ring forms a monovalent group having a bond to one atom (preferably carbon) on the aryl ring or heteroaryl ring in the structure. The AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring each have one bond to X aThe AR5 ring is bonded to the nitrogen atom via one bond. When the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring are bonded to any of the other AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring via a single bond or a linking group as described below, the ring may be a divalent group. Furthermore, among the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring, any of the rings (1) or (2) below is a divalent, trivalent, or tetravalent group as described below. (1) bonded to a ring atom of an aryl or heteroaryl ring in ring A, ring B, ring C, ring D, ring E, or ring AR5 via a single bond or a linking group; (2) It shares a ring with the A, B, C, D, E, or AR5 ring.

[0103] When ring AR5 is further bonded to ring D or ring E at another site, ring AR5 may be a divalent or trivalent group. When ring AR5 is bonded to ring AR1, ring AR2, ring AR3, ring AR4, ring A, ring B, or ring C as described below, or shares an aryl ring or heteroaryl ring with ring AR1, ring AR2, ring AR3, ring AR4, ring A, ring B, or ring C, ring AR5 may be a divalent, trivalent, or tetravalent group.

[0104] In each of the AR1 ring, the AR2 ring, the AR3 ring, the AR4 ring, and the AR5 ring, the ring having the atom having the bond as a ring-constituting atom is preferably a 5-membered ring or a 6-membered ring, more preferably a 6-membered ring. This ring may be further condensed with another ring. Examples of the 6-membered ring include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of the 6-membered ring further condensed with another ring include a naphthalene ring, a quinoline ring, a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, and a dibenzoselenophene ring. Examples of the 5-membered ring include a furan ring, a thiophene ring, a pyrrole ring, a thiazole ring, and a selenophene ring. Examples of the 5-membered ring further condensed with another ring include a benzofuran ring, a benzothiophene ring, an indole ring, and a benzoselenophene ring.

[0105] The aryl or heteroaryl ring in each of the AR1, AR2, AR3, and AR4 rings is preferably a benzene ring, a benzofuran ring, a benzothiophene ring, or a benzoselenophene ring, more preferably a benzene ring. The aryl or heteroaryl ring in the AR5 ring is preferably a benzene ring, a benzofuran ring, a benzothiophene ring, or a benzoselenophene ring, more preferably a benzene ring.

[0106] <Description of partial and overall structure> The polycyclic aromatic compound of the present invention contains at least one partial structure represented by formula (Xa-1), and preferably contains one partial structure. In formula (Xa-1), X a is C, Si, Ge, or Sn, and X a is preferably C or Si, and more preferably Si.

[0107] In formula (Xa-1), the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring may be linked to another AR1 ring, the AR2 ring, the AR3 ring, or the AR4 ring via a single bond or a linking group. a It means that there is a connection via an additional single bond or linking group in addition to the connection via the ring. When such a connection is present, it is preferable that, among the AR1 ring, the AR2 ring, the AR3 ring, or the AR4 ring, the AR1 ring and the AR2 ring are connected, or that the AR1 ring and the AR2 ring, and the AR3 ring and the AR4 ring are connected, respectively. In this case, it is preferable that they are connected via a single bond, >O, or >S, and it is more preferable that they are connected via a single bond. From the viewpoint of producing elements with higher quantum efficiency and longer lifetime, X a When is Si, Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 It is more preferable that at least two of the rings are connected to each other. It is particularly preferable that they are connected to each other by a single bond. a When is C, Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 It is more preferred that no two of the rings are linked to each other.

[0108] The polycyclic aromatic compound of the present invention contains at least one partial structure represented by formula (Xb-1), and preferably contains one partial structure. In formula (Xb-1), X b is a divalent group represented by the formula (Xb-R5), >O, or >S.

[0109] [ka]

[0110] In formula (Xb-R5), the two #'s represent the bonding positions to the D ring and the E ring, respectively. From the viewpoint of high carrier transport and good carrier balance, X b is preferably a divalent group represented by the formula (Xb-R5). That is, the formula (Xb-1) is preferably the following formula (Xb-1-R5).

[0111] [ka]

[0112] The AR5 ring is a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and the AR5 ring may be linked to the D ring and / or the E ring via a single bond or a linking group. Specific examples of the linking group include >O, >NR de ,>C(-R de )2, >Si(-R de )2, >S, >CO, >CS, >SO, >SO2, and >Se. de are each independently an alkyl, cycloalkyl, aryl, or heteroaryl, which may be substituted with an alkyl, cycloalkyl, aryl, or heteroaryl. de )2 and >Si(-R de )2 The two R de may be bonded to each other to form a ring. When the AR5 ring is linked to the D ring and / or the E ring via a single bond or a linking group, it is preferred that the AR5 ring is linked to the D ring and / or the E ring via a single bond, >O, >C(-Me)2, >C(-Ph)2, >S, or >Se. The two Ph in >C(-Ph)2 may be bonded to each other via a single bond to form a ring.

[0113] The partial structure represented by formula (Xa-1) and the partial structure represented by formula (Xb-1) are each linked to the A ring, the B ring, or the C ring in formula (1) and other partial structures by a bond or sharing of a ring to form a partial structure of the polycyclic aromatic compound represented by formula (1).

[0114] Specifically, one or two selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 in formula (Xa-1) are: is attached via a single bond to an aryl or heteroaryl ring atom in ring A, ring B, or ring C; is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting a ring of an aryl or heteroaryl ring of ring D, ring E, or ring AR5 in formula (Xb-1) which shares any ring with ring A, ring B, or ring C; Shared ring with A, B, or C; or It is bonded to ring A, ring B, or ring C, or shares a ring with ring D, ring E, or ring AR5 in formula (Xb-1), which shares any ring with ring A, ring B, or ring C.

[0115] In addition, one or two selected from the group consisting of ring D, ring E, and ring AR5 in formula (Xb-1) are: is attached via a single bond to an aryl or heteroaryl ring atom in ring A, ring B, or ring C; is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting an aryl ring or a heteroaryl ring in ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1) which shares any ring with ring A, ring B, or ring C; Shared ring with A, B, or C; or It is bonded to ring A, ring B, or ring C, or shares a ring with ring AR1, ring AR2, ring AR3, or ring AR4 in formula (Xa-1), which shares any ring with ring A, ring B, or ring C.

[0116] When ring AR1, ring AR2, ring AR3, or ring AR4 is bonded to a ring-constituting atom of an aryl ring or heteroaryl ring in ring A, ring B, or ring C via a single bond or a partial structure represented by formula (Xb-1), it is preferable that it is bonded to a ring-constituting atom of the aryl ring or heteroaryl ring in the ring (ring AR1, ring AR2, ring AR3, or ring AR4). When ring D, ring E, or ring AR5 is bonded to a ring-constituting atom of an aryl ring or heteroaryl ring in ring A, ring B, or ring C via a single bond or a partial structure represented by formula (Xa-1), it is preferable that it is bonded to a ring-constituting atom of the aryl ring or heteroaryl ring in the ring (ring D, ring E, or ring AR5).

[0117] Examples of polycyclic aromatic compounds represented by formula (1) containing one partial structure represented by formula (Xa-1) and one partial structure represented by formula (Xb-1), in which any one of the rings in formula (Xa-1) and any one of the rings in formula (Xb-1) are bonded to ring-constituting atoms of an aryl ring or heteroaryl ring in another ring via a single bond, are shown below.

[0118] [ka]

[0119] As described above, for example, a structure in which ring B and ring AR1 are bonded to each other via a single bond and ring C and ring D are bonded to each other via a single bond is represented as B-AR1C-D, and a structure in which ring B and ring D are bonded to each other via a single bond and ring AR5 and ring AR1 are bonded to each other via a single bond is represented as B-DAR5-AR1. Other examples of structures in which each partial structure is bonded to a ring-constituting atom of an aryl or heteroaryl ring in a single-bonded A ring, B ring, or C ring, or an aryl or heteroaryl ring in a ring in another partial structure, according to this notation, include the following structures:

[0120] A-AR1B-D A-AR1B-AR5 A-DB-AR1 A-AR5B-AR1 B-AR1C-AR5 A-AR1AR2-D A-AR1AR3-D A-AR1AR2-AR5 A-AR1AR3-AR5 A-DE-AR1 A-DAR5-AR1 A-AR5D-AR1 B-AR1AR2-D B-AR1AR3-D B-AR1AR2-AR5 B-AR1AR3-AR5 B-DE-AR1 B-AR5D-AR1

[0121] When each partial structure represented by formula (Xa-1) or formula (Xb-1) is bonded via a single bond to a ring-constituting atom of an aryl ring or heteroaryl ring in another ring, the substitution position is preferably such that the conjugated system becomes cross-conjugated.

[0122] As used herein, when ring A, ring B, ring C, ring AR1, ring AR2, ring AR3, ring AR4, ring AR5, ring D, or ring E is said to be shared, it means that the subject rings are integrated. An example of such a structure is a polycyclic aromatic compound represented by formula (1) containing one partial structure represented by formula (Xa-1) and one partial structure represented by formula (Xb-1), as shown below. For example, the structure represented by the following formula (AAR5DAR1) is a structure in which the A ring and the AR5 ring share a ring, and the AR1 ring and the D ring share a ring.

[0123] [ka]

[0124] Similarly, for example, the structure represented by the following formula (AAR1CAR5) indicates a structure in which the A ring and the AR1 ring share a ring, and the AR5 ring and the C ring share a ring.

[0125] [ka]

[0126] Similarly, for example, the structure represented by the following formula (AAR1AR3AR5) indicates a structure in which the A ring and the AR1 ring share a ring, and the AR5 ring and the AR3 ring share a ring.

[0127] [ka]

[0128] As described above, for example, a structure represented by (AAR5DAR1) indicates a structure in which the A ring and the AR5 ring share a ring, and the D ring and the AR1 ring share a ring. In accordance with this notation, examples of structures in which each partial structure is bonded by sharing a ring include the following structures in addition to the three examples above.

[0129] AAR1BD AAR1BAR5 ADBAR1 AAR5BAR1 BAR1CD AAR1AR2D AAR1AR3D AAR1AR2AR5 ADEAR1 ADAR5AR1 BAR1AR2D BAR1AR3D BAR1AR2AR5 BAR1AR3AR5 BDEAR1 BDAR5AR1 BAR5DAR1

[0130] The polycyclic aromatic compound of the present invention may contain a partial structure bonded via a single bond or the like and a partial structure sharing a ring. An example of such a structure, which is a polycyclic aromatic compound represented by formula (1) containing one partial structure represented by formula (Xa-1) and one partial structure represented by formula (Xb-1), is shown below. For example, in the structure represented by the following formula (B-AR1CD), the aryl ring or heteroaryl ring in ring D in (Xb-1) is bonded to a ring-constituting atom of the aryl ring or heteroaryl ring in ring C via a single bond, and ring B and ring AR1 share a ring.

[0131] [ka]

[0132] Following the above notation, other examples of structures include the following structures. A-AR1BD A-AR1BAR5 A-DBAR1 A-AR5BAR1 B-AR1CAR5 A-AR1AR2D A-AR1AR3D A-AR1AR2AR5 A-AR1AR3AR5 A-DEAR1 A-DAR5AR1 A-AR5DAR1 B-AR1AR2D B-AR1AR3D B-AR1AR2AR5 B-AR1AR3AR5 B-DEAR1 B-DAR5AR1 B-AR5DAR1

[0133] AAR1B-D AAR1B-AR5 ADB-AR1 AAR5B-AR1 BAR1C-D BAR1C-AR5 AAR1AR2-D AAR1AR3-D AAR1AR2-AR5 AAR1AR3-AR5 ADE-AR1 ADAR5-AR1 AAR5D-AR1 BAR1AR2-D BAR1AR3-D BAR1AR2-AR5 BAR1AR3-AR5 BDE-AR1 BDAR5-AR1 BAR5D-AR1

[0134] From the viewpoint of high T1 energy, a compound having a structure in which the D ring, E ring, or AR5 ring in the (Xb-1) structure is bound to the formula (Xa-1) (the formula (Xa-1) which is bound to the A ring, B ring, or C ring, or which shares any ring with the A ring, B ring, or C ring) or shares any ring is preferred. In addition, a compound in which two sp2 carbon-sp2 carbon bonds connecting aryl or heteroaryl are at the o-position or m-position is preferred because of its high T1, long life, and high efficiency. In addition, from the viewpoint of high TADF property and high efficiency, X in (Xb-1) b is a divalent group represented by the formula (Xb-R5), and it is preferable that the AR5 ring shares a ring with the A ring, the B ring, or the C ring, and it is more preferable that the AR5 ring shares a ring with the B ring or the C ring.

[0135] <Description of Substituents in Each Ring> The substituents when referring to the substituted or unsubstituted aryl ring or the substituted or unsubstituted heteroaryl ring for the A ring, the B ring, and the C ring are exemplified by the substituents formed by the formula (Xa-1), the formula (Xb-1), or the formulas (Xa-1) and (Xb-1). The other substituents are at least one substituent selected from the substituent group Zα (excluding the substituents formed by the formula (Xa-1), the formula (Xb-1), or the formulas (Xa-1) and (Xb-1)). The other substituents are preferably phenyl, methyl, t-butyl, or cyano. From the viewpoint of improving the charge transport function, it is preferable that the A ring, the B ring, and the C ring have one other substituent or are unsubstituted, and more preferably are unsubstituted, except for the aryl ring or heteroaryl ring having the substituent formed by the formula (Xa-1), the formula (Xb-1), or the formulas (Xa-1) and (Xb-1). From the viewpoint of improving the charge transport function, it is more preferable that the ring having a substituent formed by formula (Xa-1), formula (Xb-1), or formula (Xa-1) and formula (Xb-1) does not have any other substituent.

[0136] The substituents of the substituted or unsubstituted aryl ring or the substituted or unsubstituted heteroaryl ring for the D ring, the E ring, the AR1 ring, the AR2 ring, the AR3 ring, the AR4 ring, and the AR5 ring include at least one substituent selected from the substituent group Zα. The substituents are preferably phenyl, methyl, t-butyl, or cyano. From the viewpoint of improving the charge transport function, each aromatic ring in the A ring, the B ring, the C ring, the D ring, the E ring, the AR1 ring, the AR2 ring, the AR3 ring, the AR4 ring, or the AR5 ring is preferably unsubstituted or has one substituent, and more preferably unsubstituted.

[0137] <Preferred partial structure> From the viewpoint of high carrier transport and good carrier balance, the polycyclic aromatic compound of the present invention preferably has a carbazole structure, and the compound having the carbazole structure can be preferably used as a material for a hole transport layer, an electron blocking layer, or a host. The compound having a pyridine structure or a triazine structure in addition to the carbazole structure is preferably used as a host material. The compound of the present invention having a pyridine or triazine group can be preferably used as an electron transporting host, a hole blocking layer, or an electron transporting layer.

[0138] <Polycyclic aromatic compound represented by formula (1a), formula (1b), or formula (1c)> The polycyclic aromatic compound represented by formula (1) is preferably a polycyclic aromatic compound represented by formula (1a), formula (1b), or formula (1c). In this case, formula (Xa-1) is preferably represented by formula (Xa-2), and formula (Xb-1) is preferably represented by formula (Xb-2).

[0139] [ka]

[0140] The partial structure represented by formula (Xa-2) and the partial structure represented by formula (Xb-2) are each bonded to Z (a ring-constituting atom in Z, for example, a carbon atom) in ring a, ring b, or ring c in formula (1a), formula (1b), or formula (1c) via a single bond, or bonded to Z (a ring-constituting atom in Z, for example, a carbon atom) in the other partial structure bonded to Z in ring a, ring b, or ring c, or share a ring with ring a, ring b, or ring c, or bonded to ring a, ring b, or ring c, or share a ring with the other partial structure sharing any ring with ring a, ring b, or ring c, thereby constituting a partial structure of a polycyclic aromatic compound represented by formula (1a), formula (1b), or formula (1c).

[0141] Specifically, in formula (Xa-2), Ar 1 Ring, Ar 2Ring, Ar 3 ring, and Ar 4 One or two selected from the group consisting of rings are bonded to Z in ring a, ring b, or ring c via a single bond, or bonded to d, e, or AR5 ring in the partial structure represented by formula (Xb-2) which is bonded to Z in ring a, ring b, or ring c, or share a ring with ring a, ring b, or ring c, or bonded to ring a, ring b, or ring c, or share a ring with ring d, ring e, or AR5 ring in formula (Xb-2) which is bonded to ring a, ring b, or ring c. In addition, in formula (Xb-2), one or two selected from the group consisting of ring d, ring e, and AR5 ring are bonded to Z in ring a, ring b, or ring c via a single bond, or bonded to Ar in the partial structure represented by formula (Xa-2) which is bonded to Z in ring a, ring b, or ring c. 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 Ar in formula (Xa-2) is bonded to Z in a ring, or shares a ring with ring a, ring b, or ring c, or is bonded to ring a, ring b, or ring c, or shares any ring with ring a, ring b, or ring c. 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 The rings are shared. For such a structure, the above description of how the partial structure represented by formula (Xa-1) and the partial structure represented by formula (Xb-1) are partial structures of the polycyclic aromatic compound represented by formula (1) can be referred to.

[0142] In each of the formulas (1b) and (1c), Y 1 and Y 2 are each independently >NR NY ,>C(-R CY )2, >O, >Si(-R IY )2, >S, or >Se. NY , R CY , and R IYare each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CY may be bonded to each other to form a ring, and two R IY may be bonded to each other to form a ring. L is >>NR NY R when NY is preferably a substituted or unsubstituted aryl, more preferably a phenyl which may be substituted with an alkyl. CY )2 when R CY is preferably methyl or phenyl. IY )2 when R IY Y is preferably methyl or phenyl. 1 and Y 2 are each independently >NR NY ,>C(-R CY )2, >O, or >S is preferred, and >O or >S is more preferred. 1 ,Y 2 may be the same or different, and are preferably the same.

[0143] In each of formulas (1a), (1b), (1c), (Xa-2), and (Xb-2), Z is a carbon atom having a bond to another ring, or -C(-R Z )= or -N=, and R Z is hydrogen or a substituent. However, among Z constituting the e ring in formula (Xb-2), the two adjacent ones may be carbon atoms bonded to the two * in formula (Xb-2-e), respectively. Of the two adjacent Z, either Z may be bonded to either *. In formula (Xb-2-e), X b is a divalent group represented by the formula (Xb-R5), >O, >C(-R CX )2, >Si(-R IX )2, >S, or >Se, and R CXare each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CX may be bonded to each other to form a ring. CX is preferably methyl or phenyl. IX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; IX may be bonded to each other to form a ring. IX is preferably methyl or phenyl. Z in formula (Xb-2-e) has the same meaning as Z constituting the d ring in formula (Xb-2), and is a carbon atom having a bond to another ring, or -C(-R Z )= or -N=.

[0144] In each of the formulas (1a), (1b), (1c), (Xa-2), and (Xb-2), Z other than the carbon atom having a bond to another ring is -C(-R Z )= or one or two are -N= and the others are -C(-R Z )=, and in each case, -C(-R Z )= or one is -N= and the others are -C(-R Z It is more preferable that Z other than the carbon atom in each of the formulas (1a), (1b), and (1c) is -C(-R Z )=, and one of Z in each of the formulae (Xa-2) and (Xb-2) is -N= and the others are -C(-R Z In each of formulas (1a), (1b), and (1c), R ZWhen R is a substituent, examples of the substituent include a substituent formed from formula (Xa-2), formula (Xb-2), or formula (Xa-2) and formula (Xb-2). Other substituents include at least one substituent selected from the substituent group Zα (excluding the substituent formed from formula (Xa-2), formula (Xb-2), or formula (Xa-2) and formula (Xb-2)). Other substituents are preferably phenyl, methyl, or cyano. In each of formulas (1a), (1b), and (1c), R Z is preferably hydrogen. In each of the formulas (Xa-2) and (Xb-2), R Z When R is a substituent, the substituent is at least one selected from the substituent group Zα. The substituent is preferably phenyl, methyl, t-butyl, or cyano. In each of the formulas (Xa-2) and (Xb-2), R Z is preferably hydrogen.

[0145] In formula (Xa-2), X a is X in formula (Xa-1) a and the preferred ranges are also the same. Ar in formula (Xa-2) 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 For the rings, reference can be made to the descriptions of the AR1 ring, the AR2 ring, the AR3 ring, and the AR4 ring in formula (Xa-1), respectively. For example, Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 Any two rings selected from the group consisting of rings may be linked to each other via a single bond or a linking group.

[0146] In formula (Xb-2), X b is X in formula (Xb-1) b X b When is a divalent group represented by the formula (XB-R5), the AR5 ring is preferably a six-membered ring, for example, a benzene ring or a pyridine ring.

[0147] Preferred structural examples of formula (1a), formula (1b), formula (1c), formula (Xa-2), and formula (Xa-1) are shown below. Note that formula (1a), formula (1b), and formula (1c) show structures excluding each partial structure represented by formula (Xa-2) and formula (Xa-1). [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] <Replacement with heavy stable isotopes> Unless otherwise specified, each element in the polycyclic aromatic compound represented by formula (1) contains multiple naturally occurring isotopes in the natural abundance ratio. However, all or some of the elements in each structural formula may be present in excess of the natural abundance ratio (e.g., boron-11( 11 B) may contain a heavy stable isotope (at 90 atom % or more). In this specification, this is simply referred to as "substituting" a "heavy stable isotope". More specifically, at least one hydrogen can be substituted with deuterium, and at least one nitrogen can be substituted with nitrogen-15 ( 15 N), and at least one sulfur can be replaced by sulfur-33 ( 33 S), Sulfur-34( 34 S) or sulfur-36(36 S), and at least one oxygen can be replaced by oxygen-17 ( 17 O) or oxygen-18( 18 O), and at least one carbon can be replaced by carbon-13 ( 13 C), and at least one boron can be replaced by boron-11 ( 11 B). The same applies to the structures represented by formula (1a), formula (1b), or formula (1c), and this explanation applies to the structures represented by formula (1a), formula (1b), or formula (1c). By replacing at least some elements with heavy stable isotopes, in particular at least one boron with boron-11 ( 11 By replacing it with B), it is possible to extend the life of the organic electroluminescent device using the polycyclic aromatic compound represented by formula (1).

[0153] <Replacement with deuterium> All or a part of the hydrogen in the polycyclic aromatic compound represented by formula (1) may be deuterium. The same applies to the structure represented by formula (1a), formula (1b), or formula (1c), and the following description also applies to the polycyclic aromatic compound represented by formula (1a), formula (1b), or formula (1c).

[0154] For example, hydrogen atoms in the aryl or heteroaryl rings in the A, B, and C rings, and in the substituents thereof, may be replaced with deuterium atoms, and among these, there may be mentioned embodiments in which all or a part of the hydrogen atoms in the aryl or heteroaryl rings are replaced with deuterium atoms. All or a part of the hydrogen atoms in the D and E rings in the formula (Xb-1), or in the aryl and heteroaryl rings in the AR1, AR2, AR3, AR4, or AR5 rings, may be replaced with deuterium atoms. From the viewpoint of durability, it is also preferable that all or a part of the hydrogen atoms in the polycyclic aromatic compound represented by the formula (1) are deuterated.

[0155] <Specific examples of the polycyclic aromatic compound of the present invention> Specific examples of the polycyclic aromatic compound of the present invention include compounds represented by any of the following structural formulas, but the present invention is not limited thereto. [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165]

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[0186] [ka]

[0187] 2. Method for producing polycyclic aromatic compounds Polycyclic aromatic compounds represented by formula (1) can be basically produced by first bonding ring A (ring a), ring B (ring b), and ring C (ring c) with halogens at any position with O to produce an intermediate (reaction 1), then bonding fused rings containing ring A (ring a), ring B (ring b), and ring C with boron to produce partial structure (1) with halogens (reaction 2), and then linking partial structure (Xa-1) and partial structure (Xb-1) by a cross-coupling reaction (reaction 3). In reaction 1, general reactions such as nucleophilic substitution reaction and Ullmann reaction can be used, and in reaction 2, tandem hetero Friedel-Crafts reaction (sequential aromatic electrophilic substitution reaction, same below) can be used. In reaction 3, general reactions such as Suzuki-Miyaura reaction, Buchwald reaction, and Goldberg reaction can be used. It is also possible to obtain the final product by introducing B into a precursor in which the partial structure (Xa-1) and the partial structure (Xb-1) are linked in advance, by the boro-Friedel-Crafts reaction.

[0188] The second reaction is a reaction to introduce boron to bond fused rings including ring A (ring a), ring B (ring b) and ring C (ring c), as shown in the following scheme (1). First, halogen atoms between nitrogen atoms are exchanged with n-butyllithium, sec-butyllithium or t-butyllithium. Next, boron trichloride or boron tribromide is added to perform lithium-boron metal exchange, and then a tandem boron-Friedel-Crafts reaction is carried out by adding a Bronsted base such as N,N-diisopropylethylamine to obtain the target product. In the second reaction, a Lewis acid such as aluminum trichloride may be added to promote the reaction. The halogen atom Cl in the formula may be any of Cl, Br and I, and can be appropriately selected in consideration of the reactivity of the substrate.

[0189] [ka]

[0190] By appropriately selecting the raw materials to be used, it is possible to synthesize a polycyclic aromatic compound having a substituent at a desired position.

[0191] It can also be synthesized using general coupling reactions, such as the methods described in Nature Photonics, 13, 540-546 (2019) and Advanced Functional Materials, 2021,31, 2105805.

[0192] Specific examples of solvents that can be used in the above reactions include t-butylbenzene and xylene.

[0193] In the synthesis method of the above scheme (1), a tandem hetero Friedel-Crafts reaction was performed by halogen-metal exchange of the halogen atom between the nitrogen atoms with butyllithium or the like before adding boron trichloride, boron tribromide, or the like. However, the reaction can also be carried out by adding boron trichloride, boron tribromide, or the like to a precursor in which the halogen has been converted to hydrogen.

[0194] Examples of the ortho-metallation reagent used in the above scheme (1) include alkyllithiums such as methyllithium, n-butyllithium, sec-butyllithium, and t-butyllithium, and organic alkali metal compounds such as lithium diisopropylamide, lithium tetramethylpiperidide, lithium hexamethyldisilazide, and potassium hexamethyldisilazide.

[0195] In addition, examples of the metal-boron metal exchange reagent used in the above scheme (1) include boron halides such as boron trifluoride, boron trichloride, boron tribromide, and boron triiodide, boron alkoxylates, and boron aryloxylates.

[0196] Examples of the Bronsted base used in the above scheme (1) include N,N-diisopropylethylamine, triethylamine, 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethylpiperidine, N,N-dimethylaniline, N,N-dimethyltoluidine, 2,6-lutidine, sodium tetraphenylborate, potassium tetraphenylborate, triphenylborane, tetraphenylsilane, Ar4BNa, Ar4BK, Ar3B, and Ar4Si (Ar is an aryl such as phenyl).

[0197] Examples of Lewis acids used in the above scheme (1) include AlCl3, AlBr3, AlF3, BF3·OEt2, BCl3, BBr3, BI3, GaCl3, GaBr3, InCl3, InBr3, In(OTf)3, SnCl4, SnBr4, AgOTf, ScCl3, Sc(OTf)3, ZnCl2, ZnBr2, Zn(OTf)2, MgCl2, MgBr2, Mg(OTf)2, LiOTf, NaOTf, KOTf, Me3SiOTf, Cu(OTf)2, CuCl2, YCl3, Y(OTf)3, TiCl4, TiBr4, ZrCl4, ZrBr4, FeCl3, FeBr3, CoCl3, and CoBr3.

[0198] In the above scheme (1), a Brönsted base or Lewis acid may be used to promote the tandem hetero Friedel-Crafts reaction. However, when a boron halide such as boron trifluoride, boron trichloride, boron tribromide, or boron triiodide is used, acids such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide are generated as the aromatic electrophilic substitution reaction proceeds, so it is effective to use a Brönsted base to capture the acid. On the other hand, when an amino halide of boron or an alkoxylated product of boron is used, amines and alcohols are generated as the aromatic electrophilic substitution reaction proceeds, so it is not necessary to use a Brönsted base in many cases, but since the elimination ability of amino and alkoxy is low, it is effective to use a Lewis acid to promote the elimination.

[0199] The polycyclic aromatic compounds of the present invention also include those in which at least a portion of hydrogen atoms are substituted with deuterium or with halogens such as fluorine or chlorine. Such compounds can be synthesized in the same manner as described above by using raw materials in which desired sites are deuterated, fluorinated or chlorinated.

[0200] 3. Organic electroluminescent device The polycyclic aromatic compound according to the present invention can be used as a material for an organic device. Examples of the organic device include an organic electroluminescence device, an organic field effect transistor, and an organic thin-film solar cell. The polycyclic aromatic compound according to the present invention can be used in particular as an organic electroluminescence device.

[0201] 3-1. Structure of organic electroluminescent device The organic EL element according to the present embodiment will be described in detail below with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing the organic EL element according to the present embodiment.

[0202] <Structure of organic electroluminescent device> The organic EL element 100 shown in FIG. 1 has a substrate 101, an anode 102 provided on the substrate 101, a hole injection layer 103 provided on the anode 102, a hole transport layer 104 provided on the hole injection layer 103, an emitting layer 105 provided on the hole transport layer 104, an electron transport layer 106 provided on the emitting layer 105, an electron injection layer 107 provided on the electron transport layer 106, and a cathode 108 provided on the electron injection layer 107.

[0203] The organic EL element 100 may be fabricated in the reverse order, for example, to have a substrate 101, a cathode 108 provided on the substrate 101, an electron injection layer 107 provided on the cathode 108, an electron transport layer 106 provided on the electron injection layer 107, an emitting layer 105 provided on the electron transport layer 106, a hole transport layer 104 provided on the emitting layer 105, a hole injection layer 103 provided on the hole transport layer 104, and an anode 102 provided on the hole injection layer 103.

[0204] Not all of the above layers are essential, and the minimum structural unit is a structure consisting of an anode 102, an emitting layer 105, and a cathode 108. The hole injection layer 103, the hole transport layer 104, the electron transport layer 106, and the electron injection layer 107 are layers that may be provided optionally. Each of the above layers may consist of a single layer or multiple layers.

[0205] In addition to the above-mentioned "substrate / anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode" configuration, the layers constituting the organic EL element may be configured as "substrate / anode / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode", "substrate / anode / hole injection ...hole transport layer / light-emitting layer / electron injection layer / cathode", "substrate / anode / hole injection layer / hole transport layer / light-emitting layer / electron injection layer / cathode", or "substrate / anode / hole injection layer / hole transport layer / light-emitting layer / electron transport The configuration may be, for example, "substrate / anode / light-emitting layer / electron transport layer / electron injection layer / cathode", "substrate / anode / hole transport layer / light-emitting layer / electron injection layer / cathode", "substrate / anode / hole transport layer / light-emitting layer / electron transport layer / cathode", "substrate / anode / hole transport layer / light-emitting layer / electron injection layer / cathode", "substrate / anode / hole injection layer / light-emitting layer / electron injection layer / cathode", "substrate / anode / hole injection layer / light-emitting layer / electron transport layer / cathode", "substrate / anode / hole injection layer / light-emitting layer / electron transport layer / cathode", "substrate / anode / light-emitting layer / electron transport layer / cathode", or "substrate / anode / light-emitting layer / electron injection layer / cathode".

[0206] The organic EL device may further have one or both of an electron blocking layer (electron blocking layer) and a hole blocking layer (hole blocking layer). The electron blocking layer has a LUMO shallower than that of the light emitting layer and a HOMO close to that of the light emitting layer or the hole transport layer, and is disposed between the light emitting layer and the hole transport layer. Since electrons remain in the light emitting layer and do not leak to the hole transport layer, it is possible to prevent a shortened life due to deterioration of the hole transport layer and a decrease in efficiency due to a decrease in recombination efficiency. The hole blocking layer has a HOMO deeper than that of the light emitting layer and a LUMO close to that of the light emitting layer or the hole transport layer, and is disposed between the light emitting layer and the electron transport layer. Since holes remain in the light emitting layer and do not leak to the electron transport layer, it is possible to prevent a shortened life due to deterioration of the electron transport layer and a decrease in efficiency due to a decrease in recombination efficiency. The hole injection / transport layer may also serve as the electron blocking layer. The electron injection / transport layer may also serve as the hole blocking layer.

[0207] The organic EL device may further have a high T1 layer. The high T1 layer has a higher T1 than the host compound, assisting dopant compound, or emitting dopant compound used in the light-emitting layer, and is disposed between the light-emitting layer and the hole transport layer and / or between the light-emitting layer and the electron blocking layer. The value of the T1 energy varies depending on the light-emitting mechanism of the device, but has a higher T1 than the compound used in the host. By having a high T1 layer around the light-emitting layer, triplet energy can be trapped and triplet energy that does not normally lead to light emission in fluorescent molecules can be converted to singlet energy, resulting in high efficiency. The hole injection / transport layer or the electron blocking layer may also serve as the high T1 layer. The electron injection / transport layer or the hole blocking layer may also serve as the high T1 layer.

[0208] The polycyclic aromatic compound of the present invention is preferably used as a material for an organic electroluminescent device. In general, a compound having a donor structure can be used as a hole transporting host material and a hole transport layer in the light emitting layer, a compound having an acceptor structure can be used as an electron transporting host material and an electron transport layer, and a compound having both a donor structure and an acceptor structure can be used in both the hole transport layer and the host and electron transport layer in the light emitting layer. For the donor structure and the acceptor structure, for example, Advanced Functional Materials 2020, 2008332, etc. can be referred to. More specifically, the donor structure includes a triarylamine structure and a carbazole structure, and the acceptor structure includes a triazine structure, a pyrimidine structure, and a pyridine structure. The polycyclic aromatic compound according to the present invention can be used as a host material, a hole transport layer material, an electron transport layer material, etc. in the light emitting layer depending on the partial structure it has.

[0209] 3-2. Substrate in organic electroluminescent device The substrate 101 is a support for the organic EL element 100, and is usually made of quartz, glass, metal, plastic, or the like. The substrate 101 is formed into a plate, film, or sheet shape depending on the purpose, and for example, a glass plate, a metal plate, a metal foil, a plastic film, a plastic sheet, or the like is used. Among them, a glass plate and a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone are preferred. For a glass substrate, soda lime glass or alkali-free glass is used, and the thickness is sufficient to maintain mechanical strength. In addition, in order to improve the gas barrier property, a gas barrier film such as a dense silicon oxide film may be provided on at least one side of the substrate 101, and it is preferable to provide a gas barrier film when a plate, film, or sheet made of a synthetic resin with low gas barrier property is used as the substrate 101.

[0210] 3-3. Anode in organic electroluminescent device The anode 102 serves to inject holes into the light-emitting layer 105. When at least one of the hole injection layer 103 and the hole transport layer 104 is provided between the anode 102 and the light-emitting layer 105, holes are injected into the light-emitting layer 105 via these layers.

[0211] Materials for forming the anode 102 include inorganic compounds and organic compounds. Examples of inorganic compounds include metals (aluminum, gold, silver, nickel, palladium, chromium, etc.), metal oxides (indium oxide, tin oxide, indium-tin oxide (ITO), indium-zinc oxide (IZO), etc.), metal halides (copper iodide, etc.), copper sulfide, carbon black, ITO glass, and Nesa glass. Examples of organic compounds include polythiophenes such as poly(3-methylthiophene), polypyrrole, polyaniline, and other conductive polymers. In addition, materials that are used as anodes in organic EL elements can be appropriately selected and used.

[0212] 3-4. Hole injection layer and hole transport layer in organic electroluminescent device The hole injection layer 103 plays a role of efficiently injecting holes moving from the anode 102 into the light emitting layer 105 or the hole transport layer 104. The hole transport layer 104 plays a role of efficiently transporting holes injected from the anode 102 or holes injected from the anode 102 via the hole injection layer 103 to the light emitting layer 105. The hole injection layer 103 and the hole transport layer 104 are each formed by laminating or mixing one or more types of hole injection / transport materials. Alternatively, a layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole injection / transport material.

[0213] The hole injection / transport material is required to efficiently inject / transport holes from the positive electrode between electrodes to which an electric field is applied, and it is desirable that the hole injection efficiency is high and the injected holes are efficiently transported. For this purpose, it is preferable that the material has a small ionization potential, a large hole mobility, and excellent stability, and is unlikely to generate impurities that become traps during production and use. It is also preferable to use the polycyclic aromatic compound of the present invention as a material for the hole transport layer.

[0214] As the material for forming the hole injection layer 103 and the hole transport layer 104, any compound can be selected from compounds conventionally used as charge transport materials for holes in photoconductive materials, p-type semiconductors, and known compounds used in hole injection layers and hole transport layers of organic EL elements. Specific examples of such compounds include carbazole derivatives (N-phenylcarbazole, polyvinylcarbazole, etc.), biscarbazole derivatives such as bis(N-arylcarbazole) or bis(N-alkylcarbazole), triarylamine derivatives (polymers having an aromatic tertiary amino in the main chain or side chain, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-dinaphthyl-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine, N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine, N 4 ,N 4' -Diphenyl-N 4 ,N 4' -Bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4'-diamine, N 4 ,N 4 ,N 4' ,N 4'-Tetra[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine, 4,4',4"-tris(3-methylphenyl(phenyl)amino)triphenylamine and other triphenylamine derivatives, starburst amine derivatives, etc.), stilbene derivatives, phthalocyanine derivatives (metal-free, copper phthalocyanine, etc.), pyrazoline derivatives, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, quinoxaline derivatives Conductors (e.g., 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexacarbonitrile, etc.), heterocyclic compounds such as porphyrin derivatives, polysilanes, etc. As polymers, polycarbonates and styrene derivatives having the above-mentioned monomers in their side chains, polyvinylcarbazole, polysilanes, etc. are preferred, but there are no particular limitations on the compounds as long as they can form a thin film required for fabricating a light-emitting device, can inject holes from the anode, and can transport holes.

[0215] It is also known that the electrical conductivity of organic semiconductors is strongly influenced by their doping. Such organic semiconductor matrix substances consist of compounds with good electron donating or accepting properties. For doping with electron donating substances, strong electron acceptors such as tetracyanoquinone dimethane (TCNQ) or 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinone dimethane (F4TCNQ) are known (see, for example, the references "M. Pfeiffer, A. Beyer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(22), 3202-3204 (1998)" and "J. Blochwitz, M. Pfeiffer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(6), 729-731 (1998)"). These generate so-called holes by an electron transfer process in the electron donating base substance (hole transport substance). The conductivity of the base material varies considerably depending on the number and mobility of holes. Matrix materials having hole transport properties are known, for example, benzidine derivatives (TPD, etc.) or starburst amine derivatives (TDATA, etc.), or certain metal phthalocyanines (especially zinc phthalocyanine (ZnPc) and the like) (JP 2005-167175 A).

[0216] The above-mentioned hole injection layer material and hole transport layer material can also be used as hole layer materials in the form of a polymer compound obtained by polymerizing a reactive compound substituted with a reactive substituent as a monomer, or a crosslinked polymer thereof, or a pendant polymer compound obtained by reacting a main-chain polymer with the reactive compound, or a crosslinked pendant polymer thereof.

[0217] 3-5. Light-emitting layer in organic electroluminescent device The light-emitting layer 105 is a layer that emits light by recombining holes injected from the anode 102 and electrons injected from the cathode 108 between electrodes to which an electric field is applied. The material for the light-emitting layer 105 may be a compound (light-emitting compound) that is excited and emits light by the recombination of holes and electrons, and is preferably a compound that can be formed into a stable thin film shape and exhibits strong light-emitting (fluorescence) efficiency in a solid state. The polycyclic aromatic compound of the present invention is also preferably used as a material for the light-emitting layer.

[0218] The light-emitting layer may be a single layer or multiple layers, each of which is formed from materials for the light-emitting layer (host material, dopant material). The host material and the dopant material may each be one type or a combination of multiple types. The dopant material may be entirely contained in the host material or may be partially contained in the host material. As a doping method, the dopant material may be formed by co-evaporation with the host material, but it may also be mixed with the host material in advance and then simultaneously evaporated, or mixed with the host material together with an organic solvent in advance and then formed into a film by a wet film-forming method.

[0219] The amount of the host material used varies depending on the type of the host material and may be determined according to the properties of the host material. The amount of the host material used is preferably 50 to 99.999% by mass, more preferably 80 to 99.95% by mass, and even more preferably 90 to 99.9% by mass, based on the total mass of the materials for the light-emitting layer.

[0220] The amount of the dopant material used varies depending on the type of dopant material, and may be determined according to the characteristics of the dopant material. The amount of the dopant material used is preferably 0.001 to 50% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, based on the total mass of the material for the light-emitting layer. The above range is preferable in that, for example, concentration quenching phenomenon can be prevented. In addition, from the viewpoint of durability, it is also preferable that hydrogen of the dopant material is partially or entirely deuterium-deuterized.

[0221] As the dopant material, an emitting dopant and an assisting dopant material may be used. As the assisting dopant material, it is preferable to use a thermally activated delayed fluorescent material. In an organic electroluminescent device using an assisting dopant material, it is preferable that the amount of the emitting dopant material used is low in terms of preventing concentration quenching phenomenon. It is preferable that the amount of the assisting dopant material used is high in terms of the efficiency of the thermally activated delayed fluorescent mechanism. Furthermore, in an organic electroluminescent device using a thermally activated delayed fluorescent assisting dopant material, it is preferable that the amount of the emitting dopant material used is low in terms of the efficiency of the thermally activated delayed fluorescent mechanism of the assisting dopant material.

[0222] When an assisting dopant material is used, the amounts of the host material, the assisting dopant material and the emitting dopant material used are approximately 40 to 99 mass%, 59 to 1 mass% and 20 to 0.001 mass%, preferably 60 to 95 mass%, 39 to 5 mass% and 10 to 0.01 mass%, and more preferably 70 to 90 mass%, 29 to 10 mass% and 5 to 0.05 mass%, relative to the total mass of the materials for the light-emitting layer.

[0223] <Host material> Examples of host materials include fused ring derivatives of anthracene and pyrene, which have long been known as light-emitting bodies, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives, tetraphenylbutadiene derivatives, cyclopentadiene derivatives, fluorene derivatives, benzofluorene derivatives, N-phenylcarbazole derivatives, and carbazonitrile derivatives.

[0224] From the viewpoint of promoting TADF generation in the light-emitting layer without inhibiting it, the triplet energy of the host material is preferably higher than the triplet energy of the dopant or assisting dopant having the highest triplet energy in the light-emitting layer, and specifically, the triplet energy of the host material is preferably 0.01 eV or more, more preferably 0.03 eV or more, and even more preferably 0.1 eV or more. A TADF-active compound may be used as the host material.

[0225] The host material may be one kind or a combination of two or more kinds. In the case of a combination of two or more kinds, a combination of a hole transporting host material and an electron transporting host material is preferable.

[0226] The polycyclic aromatic compound of the present invention can be preferably used as a host material. The polycyclic aromatic compound of the present invention can be used alone, or can be used as a hole transporting host material, or can be used as an electron transporting host material. The polycyclic aromatic compound of the present invention is particularly preferably used as an electron transporting host material.

[0227] [Hole-transporting host material (HH) and electron-transporting host material (EH)] The hole-transporting host material (HH) and the electron-transporting host material (EH) satisfy the following relationship with respect to the HOMO (Highest Occupied Molecular Orbital) and the LUMO (Lowest Unoccupied Molecular Orbital). The HOMO of the hole-transporting host material (HH) is shallower than the HOMO of the electron-transporting host material (EH), and the LUMO of the electron-transporting host material (EH) is deeper than the LUMO of the hole-transporting host material (HH). It is also preferable that the HOMO of the emitting dopant is shallower than the HOMO of the hole-transporting host material (HH), or the LUMO of the emitting dopant is deeper than the LUMO of the electron-transporting host material (EH).

[0228] In addition, the lowest excited triplet energy level (E T1 ) is the highest E in the emission layer from the viewpoint of promoting TADF generation in the emission layer without inhibiting it. T1 E of an emitting dopant or an assisting dopant having T1 It is preferable that the E T1 is the E of the emitting dopant or assisting dopant mentioned above. T1 It is preferably 0.01 eV or more higher than the E of the host material, more preferably 0.03 eV or more higher, and further preferably 0.1 eV or more higher. T1 is preferably 2.47 eV or more, more preferably 2.49 eV or more, and even more preferably 2.56 eV or more.

[0229] It is also preferable to use a hole-transporting host material in the hole-transporting layer adjacent to the light-emitting layer, and an electron-transporting host material in the electron-transporting layer adjacent to the light-emitting layer. This is because carrier leakage and energy leakage from the light-emitting layer to the adjacent layer are less likely to occur, and a highly efficient organic EL device can be obtained. The host material (hole-transporting host material) in the light-emitting layer and the material of the hole-transporting layer may be the same or different. Also, the host material (electron-transporting host material) in the light-emitting layer and the material of the electron-transporting layer may be the same or different.

[0230] Examples of hole-transporting host materials and electron-transporting host materials that can be used together with the polycyclic aromatic compound of the invention will be given below.

[0231] [Hole-transporting host material (HH)] A preferred example of the hole transporting host material (HH) is a compound represented by formula (HH-1) or having a partial structure represented by formula (HH-1) and a structure containing at least three rings selected from the group consisting of aryl rings and heteroaryl rings. This compound preferably does not contain any of an imine structure (-N=C-; including a partial structure of a heteroaryl ring), boron (>B-), and cyano (CN).

[0232] [ka]

[0233] In formula (HH-1), Q is >O, >S, or >NA H and In the formula (HH-1), one carbon atom adjacent to the carbon atom to which Q is bonded in each of the two phenyls may be bonded to each other via L, L is a single bond, >O, >S, or >C(-A H )2, A H is hydrogen, aryl, or heteroaryl, and >C(-A H )2 in two A H may be bonded to each other.

[0234] When the hole transporting host material contains the structure represented by formula (HH-1) as a partial structure, it may contain one of the partial structures, but it is also preferable to contain two or more of the partial structures. When it contains two or more, the two or more partial structures may be the same or different from each other. The two or more partial structures may be bonded to each other by a single bond, may be bonded so that any ring contained in the partial structure is shared, or may be bonded so that any ring contained in the partial structure is condensed. The partial structure may further have a substituent selected from aryl, heteroaryl, diarylamino, or aryloxy.

[0235] The compound represented by the above formula (HH-1) or having a partial structure represented by formula (HH-1) has a structure containing at least three rings selected from the group consisting of aryl rings and heteroaryl rings. The number of rings contained is preferably 6 or more, more preferably 8 or more. In addition, it is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. The number of rings means the number of monocyclic rings, and for condensed rings, it is the number of monocyclic rings constituting the condensed rings.

[0236] The hole transporting host material is preferably a compound containing one or more partial structures selected from the group consisting of a triarylamine structure, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a condensed polycyclic ring containing phenoxazine or phenothiazine. The hole transporting host material may contain one such partial structure, but it is also preferable to contain two or more of them. When two or more are contained, the two or more partial structures may be the same or different from each other.

[0237] Specific examples of the hole-transporting host material include the following compounds. [ka]

[0238] [ka]

[0239] [ka]

[0240] [ka]

[0241] [ka]

[0242] [ka]

[0243] [ka]

[0244] [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[0249] [ka]

[0250] Of the above, HH-1-1, HH-1-2, HH-1-4 to HH-1-12, HH-1-17, HH-1-18, HH-1-20 to HH-1-24, HH-1-82, HH-1-84 to HH-1-89, HH-1-91, HH-1-92, HH-1-106 to HH-1-108, and HH-1-109 to HH-1-115 are preferred.

[0251] [Electron-transporting host material (EH)] Examples of the electron-transporting host material (EH) include compounds represented by formulae (EH-1A) to (EH-1D) or compounds having a partial structure represented by formulae (EH-1A) to (EH-1D) and a structure including at least three rings selected from the group consisting of aryl rings and heteroaryl rings.

[0252] [ka]

[0253] In formulas (EH-1A) to (EH-1D), Ar is a heteroaryl ring containing N=C as a ring-constituting moiety; Z is a single bond, -O-, -S-, or -N(-A E )-and The carbon atom next to the carbon atom to which Z is bonded and the A to which Z is bonded E and may be bonded to each other via L, L is a single bond, >O, >S or >C(-A E )2, A E is aryl, heteroaryl, or triarylsilyl, and in formula (EH-1C), any one of A E may be diarylamino; Two A's bonded to the same atom E may be bonded to each other via L, X is C, P or S; When X is C, n=2, m=1, When X is P, n=3, m=1, When X is S, n=2 and m=1~2.

[0254] The compounds represented by the above formulae (EH-1A) to (EH-1D) or having a partial structure represented by the formulae (EH-1A) to (EH-1D) have a structure containing at least three rings selected from the group consisting of aryl rings and heteroaryl rings. The number of rings contained is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more. In addition, it is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. The number of rings means the number of monocyclic rings, and for fused rings, it is the number counting the monocyclic rings constituting the fused rings.

[0255] When the electron transporting host material contains the structures represented by formulae (EH-1A) to (EH-1D) as partial structures, it may contain one of these partial structures, but it is also preferable to contain two or more of them. When it contains two or more, the two or more partial structures may be the same or different from each other. The two or more partial structures may be bonded to each other by a single bond, may be bonded so that any ring contained in the partial structure is shared, or may be bonded so that any ring contained in the partial structure is condensed. The partial structure may further have a substituent selected from aryl, heteroaryl, diarylamino, or aryloxy.

[0256] Specific examples of the electron transporting host material include the following compounds. [ka]

[0257] [ka]

[0258] [ka]

[0259] [ka]

[0260] [ka]

[0261] [ka]

[0262] [ka]

[0263] [ka]

[0264] [ka]

[0265] Another preferred example of the electron-transporting host material (a compound having a partial structure represented by formula (EH-1)) is a polycyclic aromatic compound represented by formula (EH-1b) below, or a polymer of a polycyclic aromatic compound having a plurality of structures represented by formula (EH-1b) below. [ka]

[0266] In formula (EH-1b), R 1 , R 2 , R 3 , R 4 and R 5 (Hereinafter referred to as “R 1 Each of the radicals (also referred to as "R, etc.") is independently hydrogen or a substituent. The substituent may be any substituent selected from the group Z of substituents. In formula (EH-1b), X 1 and X 2are each independently >NR (amine nitrogen), >O, >C(-R)2, >S or >Se, and X 1 and X 2 Both are never >C(-R)2, R in the >NR and >C(-R)2 are each independently hydrogen or a substituent selected from the substituent group Z, and may be further substituted with an aryl, heteroaryl, alkyl or cycloalkyl (these are the second substituents), and R in the >NR and >C(-R)2 are each independently bonded to at least one of the ring a, ring b and ring c via a linking group or a single bond. Y 1 , Y 2 , Y 3 , Y 4 , Y 5 and Y 6 (hereinafter, "Y 1 etc." are each independently =C(-R)- or =N- (pyridine nitrogen), and at least one is =N- (pyridine nitrogen); Each R in the =C(-R)- is independently hydrogen or a substituent selected from the substituent group Z. R 1 , R 2 , R 3 , R 4 and R 5 , and the Y 1 ~Y 6 Adjacent groups among R in =C(-R)- as the formula may be bonded to each other to form an aryl ring or a heteroaryl ring together with at least one of the ring a, ring b, and ring c, and at least one hydrogen atom in the formed ring may be substituted with an aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy (all of these, first substituents), and at least one hydrogen atom in these may be further substituted with an aryl, heteroaryl, alkyl, or cycloalkyl (all of these, second substituents). At least one hydrogen in the compound and structure represented by formula (EH-1b) may be replaced with cyano, halogen or deuterium.

[0267] In formula (EH-1b), R 1 , R 2 , R 3 , R 4 and R 5 are all hydrogen or R 3 and R 4 are both hydrogen, and R 1 , R 2 and R 5 It is preferable that at least one selected from the group consisting of is a substituent other than hydrogen, and the others are hydrogen. As the substituent, an aryl which may be substituted with an alkyl, an alkyl, or a heteroaryl, a heteroaryl which may be substituted with an alkyl or an aryl, or a diarylamino which may be substituted with an alkyl or an aryl is preferable. In this case, the alkyl is preferably an alkyl having 1 to 6 carbon atoms (methyl, t-butyl, etc.), the aryl is preferably phenyl or biphenyl, and the heteroaryl is preferably triazinyl, carbazolyl (2-carbazolyl, 3-carbazolyl, 9-carbazolyl, etc.), pyrimidinyl, pyridinyl, dibenzofuranyl, or dibenzothienyl. Specific examples include phenyl, biphenyl, diphenyltriazinyl, carbazolyltriazinyl, monophenylpyrimidinyl, diphenylpyrimidinyl, carbazolyltriazinyl, pyridinyl, dibenzofuranyl, and dibenzothienyl.

[0268] Y 1 etc. are each independently =C(-R)- or =N-, and at least one is =N-. 1 ~Y 6 Any of Y may be =N-. 1 and Y 6 =N-(a ring is a pyrimidine ring), Y 1 or Y 6 =N-(a ring is a pyridine ring), Y 2 and Y5 =N- (ring b and ring c are pyridine rings), Y 3 and Y 4 =N- (ring b and ring c are pyridine rings), Y 2 ~Y 5 =N-(ring b and ring c are pyrimidine rings), Y 1 , Y 3 , Y 4 and Y 6 =N- (ring a is a pyrimidine ring, rings b and c are pyridine rings), Y 1 , Y 2 , Y 5 and Y 6 =N- (ring a is a pyrimidine ring, rings b and c are pyridine rings), Y 1 ~Y 6 =N-(ring a, ring b and ring c are pyrimidine rings), Y 2 or Y 5 is =N-(ring b or ring c is a pyridine ring).

[0269] In addition to the above =N- arrangement, X 1 and X 2 is preferably >O, and a polycyclic aromatic compound containing a partial structure represented by any one of the following formulas is preferred. [ka]

[0270] In particular, polycyclic aromatic compounds containing a partial structure represented by formula (EH-1b-N1) have a higher E S1 , high E T1 , small ΔE S1T1 has. Specific examples of the polycyclic aromatic compound represented by formula (EH-1b) are shown below.

[0271] [ka]

[0272] [ka]

[0273] [ka]

[0274] [ka]

[0275] [ka]

[0276] [ka]

[0277] Of the above, EH-1-1 to EH-1-4, EH-1-10, EH-1-21 to EH-1-25, EH-1-32, EH-1-33, EH-1-51 to EH-1-59, EH-1-61, EH-1-66, EH-1-68, EH-1-71, EH-1-72, EH-1-90, EH-1-94 to EH-1-99, EH-1-100, EH-1-101, EH-1-104, EH-1-115, EH-1-117, EH-1-120, EH-1-122, EH-1-123, and EH-1-127 to EH-1-130 are preferred.

[0278] [Combination of hole-transporting host material and electron-transporting host material] The combination of the hole-transporting host material and the electron-transporting host material is such that the HOMO, LUMO and lowest excited triplet energy levels (E T1 ) is selected. Regarding the HOMO and LUMO, a combination is selected in which the HOMO(HH) of the hole-transporting host material is shallower than the HOMO(EH) of the electron-transporting host material and the LUMO(EH) of the electron-transporting host material is deeper than the LUMO(HH) of the hole-transporting host material. More specifically, a combination in which the HOMO(HH) is shallower than the HOMO(EH) by 0.10 eV or more and the LUMO(HH) is deeper than the HOMO(EH) by 0.10 eV or more is preferred, a combination in which the HOMO(HH) is shallower than the HOMO(EH) by 0.20 eV or more and the LUMO(HH) is deeper than the HOMO(EH) by 0.20 eV or more is more preferred, and a combination in which the HOMO(HH) is shallower than the HOMO(EH) by 0.25 eV or more and the LUMO(HH) is deeper than the HOMO(EH) by 0.25 eV or more is even more preferred.

[0279] The hole transporting host material and the electron transporting host material may be a combination that forms an association called an exciplex. It is generally known that an exciplex is easily formed between a material having a relatively deep LUMO level and a material having a shallow HOMO level. The interaction between the hole transporting host material and the electron transporting host material, specifically, whether or not an exciplex is formed, can be determined by forming a single layer film consisting of only the hole transporting host material and the electron transporting host material under the same conditions as those for forming the light-emitting layer, measuring the emission spectrum (fluorescence spectrum, phosphorescence spectrum), and comparing the obtained emission spectrum with the emission spectrum shown by each of the hole transporting host material and the electron transporting host material alone. It can be determined by the spectrum of the mixed film containing the hole transporting host material and the electron transporting host material showing an emission wavelength different from both the spectrum of the film of the hole transporting host material and the spectrum of the film of the electron transporting host material. Specifically, it is sufficient to use the difference in the peak wavelength of the spectrum as an index of 10 nm or more.

[0280] Specific examples of the combination of a hole-transporting host material and an electron-transporting host material that do not form an exciplex include the following combinations. T1In order to satisfy the physical property values, the hole transporting host material is preferably a compound having carbazole, dibenzofuran, dibenzothiophene, triarylamine, indolocarbazole and benzoxazinophenoxazine as a partial structure, more preferably a compound having carbazole, dibenzofuran and dibenzothiophene as a partial structure, and even more preferably a compound having carbazole as a partial structure.Similarly, the electron transporting host material is preferably a compound having pyridine, triazine, phosphine oxide, benzofuropyridine and dibenzoxasiline as a partial structure, more preferably a compound having triazine, phosphine oxide, benzofuropyridine and dibenzoxasiline as a partial structure, and even more preferably a compound having triazine.

[0281] More specifically, the hole-transporting host material is preferably selected from the group consisting of HH-1-1, HH-1-2, HH-1-4 to HH-1-12, HH-1-17, HH-1-18, HH-1-20 to HH-1-24, HH-1-82, HH-1-84 to HH-1-89, HH-1-91, HH-1-92, and HH-1-106 to HH-1-108, and the electron-transporting host material is preferably selected from the group consisting of EH-1-1 to EH-1-4, EH It is preferable that the copolymer is selected from the group consisting of EH-1-10, EH-1-21 to EH-1-25, EH-1-32, EH-1-33, EH-1-51 to EH-1-59, EH-1-61, EH-1-71, EH-1-72, EH-1-90, EH-1-100, EH-1-101, EH-1-104, EH-1-117, EH-1-120, EH-1-122, EH-1-123, and EH-1-127 to EH-1-130. Preferred examples of combinations include compound HH-1-1 and compound EH-1-22, compound HH-1-1 and compound EH-1-23, compound HH-1-1 and compound EH-1-24, compound HH-1-2 and compound EH-1-22, compound HH-1-2 and compound EH-1-23, compound HH-1-2 and compound EH-1-24, or compound HH-1-1 and compound EH-1-128.

[0282] Specific examples of the combination of a hole-transporting host material and an electron-transporting host material that form an exciplex include the following combinations. T1 In order to satisfy the physical property values, the hole transporting host material is preferably a compound having carbazole, triarylamine, indolocarbazole and benzoxazinophenoxazine as a partial structure, more preferably a compound having triarylamine, indolocarbazole and benzoxazinophenoxazine as a partial structure, and even more preferably a compound having triarylamine as a partial structure.Similarly, the electron transporting host material is preferably a compound having pyridine, triazine, phosphine oxide and benzofuropyridine as a partial structure, more preferably a compound having triazine, phosphine oxide, benzofuropyridine and dibenzoxasiline as a partial structure, and even more preferably a compound having phosphine oxide and triazine.

[0283] More specifically, the hole-transporting host material is preferably selected from the group consisting of HH-1-1, HH-1-2, HH-1-11, HH-1-12, HH-1-17, HH-1-18, HH-1-23, HH-1-24, and HH-1-115, and the electron-transporting host material is preferably selected from the group consisting of EH-1-1 to EH-1-4, EH-1-21 to EH-1-25, and EH-1-5. It is preferable that the copolymer is selected from the group consisting of EH-1-1 to EH-1-57, EH-1-59, EH-1-66, EH-1-68, EH-1-90, EH-1-94, EH-1-99, EH-1-100, EH-1-101, EH-1-104, EH-1-117, EH-1-120, EH-1-122, EH-1-123, and EH-1-127 to EH-1-130. Preferred examples of combinations include compound HH-1-1 and compound EH-1-21, compound HH-1-2 and compound EH-1-21, compound HH-1-12 and compound EH-1-94, compound HH-1-12 and compound EH-1-117, compound HH-1-1 and compound EH-1-130, compound HH-1-33 and compound EH-1-117, compound HH-1-48 and compound EH-1-117, compound HH-1-49 and compound EH-1-117, and compound HH-1-115 and compound EH-1-99.

[0284] For other specific combinations of hole-transporting host materials and electron-transporting host materials, see Organic Electronics 66(2019)227-24, Advanced.Functional Materials 25(2015)361-366., Advanced Materials 26(2014)4730-4734., ACS Applied Materials and Interfaces 8(2016)32984-32991., ACS Applied Materials and Interfaces 2016,8,9806-9810, ACS Applied Materials and Interfaces 2016,8,32984-32991, Journal of Materials Chemistry C,2018,6,8784-8792, Angewante Chemie International Edition.2018,57,12380-12384, Advanced Functional Materials,24,2014,3970,Advanced Reference can be made to descriptions such as Materials, 26, 2014, 5684, Synthetic Metals, 201, 2015, 49, and Nature Photonics, 16, 212-218 (2022).

[0285] <Dopant materials (emitting dopant materials)> Known compounds can be used as the dopant material, and can be selected from various materials depending on the desired emission color.Specific examples of the dopant material include condensed ring derivatives such as phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopyrene, dibenzopyrene, rubrene, and chrysene, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, benzotriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, stilbene derivatives, thiophene derivatives, and tetraphenylbutadiene. derivatives, cyclopentadiene derivatives, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives (JP Patent Publication No. 245087 / 1999), bisstyrylarylene derivatives (JP Patent Publication No. 247278 / 1990), diazaindacene derivatives, furan derivatives, benzofuran derivatives, isobenzofuran derivatives such as phenylisobenzofuran, dimesitylisobenzofuran, di(2-methylphenyl)isobenzofuran, di(2-trifluoromethylphenyl)isobenzofuran, and phenylisobenzofuran coumarin derivatives such as dibenzofuran derivatives, 7-dialkylaminocoumarin derivatives, 7-piperidinocoumarin derivatives, 7-hydroxycoumarin derivatives, 7-methoxycoumarin derivatives, 7-acetoxycoumarin derivatives, 3-benzothiazolylcoumarin derivatives, 3-benzimidazolylcoumarin derivatives, and 3-benzoxazolylcoumarin derivatives, dicyanomethylenepyran derivatives, dicyanomethylenethiopyran derivatives, polymethine derivatives, cyanine derivatives, oxobenzoanthracene derivatives, xanthene derivatives, and rhodamine derivatives. conductors, fluorescein derivatives, pyrylium derivatives, carbostyril derivatives, acridine derivatives, oxazine derivatives, phenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives, 1,2,5-thiadiazolopyrene derivatives, pyrromethene derivatives, perinone derivatives, pyrrolopyrrole derivatives, squarylium derivatives, violanthrone derivatives, phenazine derivatives, acridone derivatives, deazaflavin derivatives, fluorene derivatives and benzofluorene derivatives.

[0286] As the emitting dopant material, it is also preferable to use a polycyclic aromatic compound containing boron described in International Publication No. 2015 / 102118, International Publication No. 2020 / 162600, paragraphs 0097 to 0269 of JP-A-2021-077890, etc. The polycyclic aromatic compound having a boron atom may be a phosphor or a TADF material (thermally activated delayed phosphor). The polycyclic aromatic compound having a boron atom is preferably a blue light-emitting compound.

[0287] Preferred examples of the boron-containing polycyclic aromatic compound include compounds represented by the following formula (12), formula (13) or formula (14). [ka]

[0288] ring A, ring B, ring C and ring D each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; Y is B (boron), X 1 , X 2 , X 3 and X 4 are each independently >O, >NR, >S or >Se, R of the >NR is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl or a substituted or unsubstituted alkyl, and R of the >NR may be bonded to the A ring, the B ring, the C ring and / or the D ring via a linking group or a single bond; R 1 and R 2 each independently represents hydrogen, alkyl having 1 to 6 carbon atoms, aryl having 6 to 12 carbon atoms, heteroaryl having 2 to 15 carbon atoms, or diarylamino (wherein aryl has 6 to 12 carbon atoms); Z 1 and Z 2 are each independently any substituent selected from the substituent group Z, 1may be bonded to the ring A via a linking group or a single bond; Z 2 may be bonded to the C ring via a linking group or a single bond, and At least one hydrogen in the compound represented by formula (12) may be replaced by cyano, halogen or deuterium.

[0289] Substituents when the aryl or heteroaryl rings in the rings A, B, C and D of formula (12) are substituted, and Z 1 , Z 2 Examples of the substituent include a substituent selected from the substituent group Z.

[0290] X in Equation (12) 1 , X 2 , X 3 and X 4 are each independently >O, >NR, >S or >Se, and each R in the >NR is independently an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, a cycloalkyl having 3 to 12 carbon atoms, or an alkyl having 1 to 6 carbon atoms. In the compound represented by formula (12), from the viewpoint of high TADF properties, Z 1 and Z 2 is preferably diphenylamino which may have a substituent or N-carbazolyl which may have a substituent, and more preferably diphenylamino which may have a substituent. As the diphenylamino which may have a substituent, unsubstituted diphenylamino or diphenylamino having at least one alkyl having 1 to 4 carbon atoms is preferable, and unsubstituted diphenylamino or diphenylamino having at least one methyl at the m-position or o-position relative to N is more preferable. From the viewpoint of ease of synthesis and emission wavelength, the aryl ring or heteroaryl ring in the A ring, the B ring, the C ring, and the D ring is preferably Z 1 and Z 2 It is preferable that the other substituents are not substituted or are only alkyl groups having 1 to 6 carbon atoms. 1 and Z 2 It is more preferable that no substituents are present other than the above. Examples of compounds represented by formula (12) are shown below.

[0291] [ka]

[0292] [ka]

[0293] [ka]

[0294] [ka]

[0295] In formula (13) and formula (14), A 11 Ring, A 21 Ring, A 31 Ring, B 11 Ring, B 21 Ring, C 11 Ring, and C 31 each ring is independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; Y 11 , Y 21 , Y 31 is B (boron), X 11 , X 12 , X 21 , X 22 , X 31 , and X 32 are each independently >O, >NR, >S, or >Se, and R of the >NR is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, or a substituted or unsubstituted alkyl, and R of the >NR is connected to A by a linking group or a single bond. 11 Ring, A 21 Ring, A 31 Ring, B 11 Ring, B21 Ring, C 11 Ring, and / or C 31 may be attached to a ring, At least one hydrogen in the compounds represented by formula (13) and formula (14) may be replaced by cyano, halogen or deuterium.

[0296] A in Equation (13) and Equation (14) 11 Ring, A 21 Ring, A 31 Ring, B 11 Ring, B 21 Ring, C 11 Ring, and C 31 Substituents on the aryl or heteroaryl ring when substituted and Z 1 , Z 2 Examples of the substituent include a substituent selected from the substituent group Z.

[0297] X in formula (13) and formula (14) 11 , X 12 , X 21 , X 22 , X 31 , and X 32 are each independently >O, >NR, >S or >Se, and each R in the >NR is independently an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, a cycloalkyl having 3 to 12 carbon atoms, or an alkyl having 1 to 6 carbon atoms.

[0298] Examples of the compound represented by formula (13) or formula (14) are shown below. [ka]

[0299] [ka]

[0300] <Assisting dopant (thermally activated delayed fluorescent material or phosphorescent material)> The light-emitting layer preferably contains an assisting dopant in addition to the emitting dopant and the host material. The assisting dopant is preferably a thermally activated delayed fluorescent material or a phosphorescent material. In this embodiment, it is also preferable to use a combination of a hole transporting host material and an electron transporting host material as the host, and the polycyclic aromatic compound of the present invention can be preferably used as the electron transporting host material.

[0301] The lowest excited triplet energy level E(1,T,Sh) obtained from the shoulder on the short-wavelength side of the peak of the phosphorescence spectrum of the host compound is preferably higher than the lowest excited triplet energy levels E(2,T,Sh) and E(3,T,Sh) of the emitting dopant or assisting dopant having the highest lowest excited triplet energy level in the emitting layer, from the viewpoint of promoting rather than inhibiting the generation of TADF in the emitting layer. Specifically, the lowest excited triplet energy level E(1,T,Sh) of the host compound is preferably higher by 0.01 eV or more than E(2,T,Sh) and E(3,T,Sh), more preferably higher by 0.03 eV or more, and even more preferably higher by 0.1 eV or more.

[0302] [Thermal activated delayed phosphor] "Thermally activated delayed fluorescent material" refers to a compound that absorbs thermal energy, undergoes reverse intersystem crossing from the lowest excited triplet state to the lowest excited singlet state, and then radiatively deactivates from the lowest excited singlet state to emit delayed fluorescence. However, "thermally activated delayed fluorescent material" also includes compounds that undergo higher triplets in the process of excitation from the lowest excited triplet state to the lowest excited singlet state. For example, see a paper by Monkman et al. of Durham University (NATURE COMMUNICATIONS, 7: 13680, DOI: 10.1038 / ncomms13680), a paper by Hosokai et al. of the National Institute of Advanced Industrial Science and Technology (Hosokai et al., Sci. Adv. 2017; 3: e1603282), a paper by Sato et al. of Kyoto University (Scientific Reports, 7: 4820, DOI: 10.1038 / s41598-017-05007-7), and a paper by Sato et al. of Kyoto University (Scientific Reports, 7: 4820, DOI: 10.1038 / s41598-017-05007-7). Examples of such reviews include a conference presentation by Sato et al. (98th Spring Annual Meeting of the Chemical Society of Japan, Presentation No.: 2I4-15, Mechanism of Highly Efficient Emission in Organic Electroluminescence Using DABNA as an Emitting Molecule, Graduate School of Engineering, Kyoto University), a review by Bui et al. (DOI: 10.3762 / bjoc.14.18), a review by Duan et al. (DOI: 10.1063 / 1.5143501), a review by Ding et al. (DOI: 10.1088 / 1674-4926 / 42 / 5 / 050201), and a review by Xie et al. (DOI: 10.1002 / adom.202002204). In the present invention, when a sample containing the target compound is measured for its fluorescence lifetime at 300K, if a slow fluorescent component is observed, the target compound is determined to be a "thermally activated delayed fluorescent material". Here, the term "slow fluorescent component" refers to a component whose fluorescent lifetime is 0.1 μsec or longer. The fluorescent lifetime can be measured, for example, using a fluorescent lifetime measuring device (manufactured by Hamamatsu Photonics KK, C11367-01).

[0303] In the light-emitting layer further containing "thermally activated delayed phosphor" as an assisting dopant, the above-mentioned polycyclic aromatic compound containing boron is preferably used as an emitting dopant. That is, the "thermally activated delayed phosphor" can function as an assisting dopant that assists the emission of the above-mentioned polycyclic aromatic compound containing boron. In this specification, an organic electroluminescent device that uses a thermally activated delayed fluorescent material as an assisting dopant is sometimes referred to as a "TAF device" (TADF Assisting Fluorescence device). The "host compound" in a TAF element means a compound whose lowest excited singlet energy level, determined from the shoulder on the short-wavelength side of the peak of the fluorescence spectrum, is higher than that of the thermally activated delayed phosphor serving as the assisting dopant and the emitting dopant.

[0304] The thermally activated delayed phosphor (TADF compound) used in the TAF element is preferably a donor-acceptor type thermally activated delayed phosphor (DA type TADF compound) designed to localize the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) in the molecule using an electron-donating substituent called a donor and an electron-accepting substituent called an acceptor, thereby causing efficient reverse intersystem crossing.

[0305] In this specification, the term "electron-donating substituent" (donor) refers to a substituent or partial structure in which the HOMO is localized in the thermally activated delayed fluorescent substance molecule, and the term "electron-accepting substituent" (acceptor) refers to a substituent or partial structure in which the LUMO is localized in the thermally activated delayed fluorescent substance molecule.

[0306] In general, thermally activated delayed phosphors using donors and acceptors have large spin-orbit coupling (SOC) due to their structure, and small exchange interaction between HOMO and LUMO, resulting in a low ΔE S1T1 Since the luminescence wavelength is small, a very fast reverse intersystem crossing rate can be obtained. By using the above-mentioned boron-containing polycyclic aromatic compound as an emitting dopant and a thermally activated delayed phosphor (TADF material) as an assisting dopant, an element that satisfies any one or all of high efficiency, high color purity, and long life can be obtained. The thermally activated delayed phosphor may be a compound whose emission spectrum at least partially overlaps with the absorption spectrum of the emitting dopant. The emitting dopant and the thermally activated delayed phosphor may both be included in the same layer, or may be included in adjacent layers or other adjacent layers.

[0307] As the thermally activated delayed phosphor in the TAF element, for example, a compound in which a donor and an acceptor are bonded directly or via a spacer can be used. As the electron donor group (donor structure) and electron acceptor group (acceptor structure) used in the thermally activated delayed phosphor of the present invention, for example, the structure described in Chemistry of Materials, 2017, 29, 1946-1963 can be used. Donor structures include carbazole, dimethylcarbazole, di-tert-butylcarbazole, dimethoxycarbazole, tetramethylcarbazole, benzofluorocarbazole, benzothienocarbazole, phenyldihydroindolocarbazole, phenylbicarbazole, bicarbazole, tercarbazole, diphenylcarbazolylamine, tetraphenylcarbazolyldiamine, phenoxazine, dihydrophenazine, phenothiazine, dimethyldihydroacridine, diphenylamine, bis(tert-butylphenyl)amine, N1-(4-(diphenylamino)phenyl)-N4,N4-diphenylbenzene-1,4-diamine, dimethyltetraphenyldihydroacridinediamine, tetramethyl-dihydro-indenoacridine, and diphenyl-dihydrodibenzoazasiline.Acceptor structures include sulfonyldibenzene, benzophenone, phenylenebis(phenylmethanone), benzonitrile, isonicotinonitrile, phthalonitrile, isophthalonitrile, paraphthalonitrile, benzenetricarbonitrile, triazole, oxazole, thiadiazole, benzothiazole, benzobis(thiazole), benzoxazole, benzobis(oxazole), quinoline, benzimidazole, dibenzoquinoxaline, heptaazaphenalene, thioxanthone dioxide, dimethylanthracenone, anthracenedione, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, fluorene dicarbonitrile, triphenyltriazine, pyrazinedicarbonitrile, pyrimidine, phenylpyrimidine, methylpyrimidine, pyridinedicarbonitrile, dibenzoquinoxalinedicarbonitrile, bis(phenylsulfonyl)benzene, dimethylthioxanthene dioxide, thianthrene tetraoxide, and tris(dimethylphenyl)borane. In particular, the compound having thermally activated delayed fluorescence in the TAF element is preferably a compound having at least one partial structure selected from carbazole, phenoxazine, acridine, triazine, pyrimidine, pyrazine, thioxanthene, benzonitrile, phthalonitrile, isophthalonitrile, diphenylsulfone, triazole, oxadiazole, thiadiazole, and benzophenone.

[0308] The compound used as the assisting dopant of the light-emitting layer in the TAF element is preferably a thermally activated delayed phosphor, and its emission spectrum is at least partially overlapped with the absorption peak of the emitting dopant. In the following, the compound that can be used as the second component (thermally activated delayed phosphor) of the light-emitting layer in the TAF element is exemplified. However, the compound that can be used as the thermally activated delayed phosphor in the TAF element is not limited to the following exemplified compounds.

[0309] [ka]

[0310] [ka]

[0311] [ka]

[0312] [ka]

[0313] [ka]

[0314] Furthermore, as the thermally activated delayed phosphor, a compound represented by any one of the following formulae (AD1), (AD2) and (AD3) can also be used. [ka]

[0315] In the above formulas (AD1), (AD2) and (AD3), M is each independently a single bond, -O-, >N-Ar or >CAr2, and is preferably a single bond, -O- or >N-Ar from the viewpoint of the depth of the HOMO of the partial structure to be formed and the height of the lowest excited singlet energy level and the lowest excited triplet energy level. J is a spacer structure separating the donor partial structure and the acceptor partial structure, and is each independently an arylene having 6 to 18 carbon atoms, and is preferably an arylene having 6 to 12 carbon atoms from the viewpoint of the magnitude of the conjugation exuded from the donor partial structure and the acceptor partial structure. More specifically, phenylene, methylphenylene and dimethylphenylene are exemplified. Q is each independently =C(-H)- or =N-, and is preferably =N- from the viewpoint of the shallowness of the LUMO of the partial structure to be formed and the height of the lowest excited singlet energy level and the lowest excited triplet energy level. Ar are each independently hydrogen, an aryl having 6 to 24 carbon atoms, a heteroaryl having 2 to 24 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 18 carbon atoms, and from the viewpoint of the HOMO depth and the height of the lowest excited singlet energy level and the lowest excited triplet energy level of the partial structure to be formed, preferably hydrogen, an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 14 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 6 to 10 carbon atoms, more preferably hydrogen, phenyl, tolyl, xylyl, mesityl, biphenyl, pyridyl, bipyridyl, triazinyl, carbazolyl, dimethylcarbazolyl, di-tert-butylcarbazolyl, benzimidazolyl, or phenylbenzimidazolyl, and further preferably hydrogen, phenyl, or carbazolyl. m is 1 or 2. n is an integer of (6-m) or less, and from the viewpoint of steric hindrance, preferably an integer of 4 to (6-m). Furthermore, at least one hydrogen in the compounds represented by the above formulas may be substituted with a halogen or deuterium.

[0316] More specifically, the compounds used as the second component in this embodiment are preferably 4CzBN, 4CzBN-Ph, 5CzBN, 3Cz2DPhCzBN, 4CzIPN, 2PXZ-TAZ, Cz-TRZ3, BDPCC-TPTA, MA-TA, PA-TA, FA-TA, PXZ-TRZ, DMAC-TRZ, BCzT, DCzTrz, DDCzTRz, spiroAC-TRZ, Ac-HPM, Ac-PPM, Ac-MPM, TCzTrz, TmCzTrz and DCzmCzTrz.

[0317] The compound used as the second component in this embodiment may be a donor-acceptor type TADF compound represented by DA in which one donor D and one acceptor A are bonded directly or via a linking group; however, a compound having a structure represented by the following formula (DAD1) in which multiple donors D are bonded directly or via a linking group to one acceptor A is preferred because it provides an organic electroluminescent device with better properties. (D 1 -L 1 )nA 1 (DAD1) Formula (DAD1) includes compounds represented by the following formula (DAD2). D 2 -L 2 -A 2 -L 3 -D 3 (DAD2) In the formula (DAD1) and the formula (DAD2), D 1 , D 2 and D. 3 Each independently represents a donor group. As the donor group, the above-mentioned donor structure can be used. A 1 and A 2 Each of L independently represents an acceptor group. As the acceptor group, the above-mentioned acceptor structure can be used. 1 , L 2 and L 3Each of L independently represents a single bond or a conjugated linking group. The conjugated linking group is a spacer structure that separates a donor group and an acceptor group, and is preferably an arylene having 6 to 18 carbon atoms, and more preferably an arylene having 6 to 12 carbon atoms. 1 , L 2 and L 3 More preferably, each independently represents phenylene, methylphenylene, or dimethylphenylene. 1 represents an integer equal to or less than the maximum number that can be substituted. For example, n may be selected within the range of 2 to 10, or within the range of 2 to 6. When n is 2, the compound is represented by formula (DAD2). 1 may be the same or different, and n L 1 may be the same or different. Preferred specific examples of the compounds represented by formula (DAD1) and formula (DAD2) include 2PXZ-TAZ and the following compounds, but the second component that can be used in the present invention is not limited to these compounds.

[0318] [ka]

[0319] [Phosphorescent materials (assisting dopants)] In the light-emitting layer, a phosphorescent material may be used as an assisting dopant. In this specification, an organic electroluminescent device using a phosphorescent material as an assisting dopant may be referred to as a phosphorescence-assisted element, a phosphorescence-sensitized fluorescent element, or a PSF element. Phosphorescent materials utilize the intramolecular spin-orbit interaction (heavy atom effect) of metal atoms to obtain light emission from an excited triplet state. As such phosphorescent materials, for example, luminescent metal complexes can be used. As luminescent metal complexes, for example, compounds represented by the following formula (B-1) and the following formula (B-2) can be used.

[0320] [ka]

[0321] In formula (B-1), M is at least one selected from the group consisting of Ir, Pt, Au, Eu, Ru, Re, Ag, and Cu, n is an integer of 1 to 3, and each "XY" is independently a bidentate ligand. In the formula (B-2), M is at least one selected from the group consisting of Pt, Re, and Cu, and "WXYZ" is a tetradentate ligand. In the formula (B-1), M is preferably Ir and n is preferably 3 from the viewpoints of efficiency and life. In the formula (B-2), M is preferably Pt from the viewpoints of efficiency and life. The ligand (XY) in the formula (B-1) has at least one ligand selected from the group consisting of the following: The ligand (WXYZ) in the formula (B-2) has at least one ligand selected from the group consisting of the following as a part.

[0322] [ka]

[0323] During the ceremony, --- binds to the central metal M, Y is independently BR e , N.R. e , P.R. e , O, S, Se, C=O, S=O, SO2, CR e R f , SiR e R f , or GeR e R f and Each aromatic carbon CH in the ring may be independently replaced by N; R e and R f may be optionally fused or linked to form a ring, R a , R b , R c, and R d may each independently be unsubstituted or substituted with from 1 to the maximum number of possible substitutions; R a , R b , R c , R d , R e , and R f are each independently hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, or combinations thereof; However, R a , R b , R c , and R d Any two adjacent substituents in may be fused or linked to form a ring or to form a multidentate ligand.

[0324] Examples of the compound represented by formula (B-1) include Ir(ppy)3, Ir(ppy)2(acac), Ir(mppy)3, Ir(PPy)2(m-bppy), BtpIr(acac), Ir(btp)2(acac), Ir(2-phq)3, Hex-Ir(phq), Ir(fbi)2(acac), and fac-Tris(2-(3-p-xylyl)phenyl)pyridine. iridium(III), Eu(dbm)3(Phen), Ir(piq)3, Ir(piq)2(acac), Ir(Fliq)2(acac), Ir(Flq)2(acac), Ru(dtb-bpy)3·2(PF6), Ir(2-phq)3, Ir(BT)2(acac), Ir(DMP)3 , Ir(Mphq)3IR(phq)2tpy, fac-Ir(ppy)2Pc, Ir(dp)PQ2, Ir(Dpm)(Piq)2, Hex-Ir(piq)2(acac), Hex-Ir(piq)3, Ir(dmpq)3, Ir(dmpq)2(acac), FPQIrpic, etc.

[0325] Other examples of the compound represented by formula (B-1) include the following compounds: [ka]

[0326] [ka]

[0327] [ka]

[0328] In addition, iridium complexes described in JP 2006-089398 A, JP 2006-080419 A, JP 2005-298483 A, JP 2005-097263 A, and JP 2004-111379 A, ​​U.S. Patent Application Publication No. 2019 / 0051845, etc., or Advanced Materials, 26: 7116-7121, NPG Asia Materials 13, 53 (2021), Applied Physics Letters, 117, 253301 (2020), Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements, Chapter 5, etc. may be used.

[0329] 3-6. Electron injection layer and electron transport layer in organic electroluminescent device The electron injection layer 107 plays a role of efficiently injecting electrons moving from the cathode 108 into the light-emitting layer 105 or the electron transport layer 106. The electron transport layer 106 plays a role of efficiently transporting electrons injected from the cathode 108 or electrons injected from the cathode 108 via the electron injection layer 107 to the light-emitting layer 105. The electron transport layer 106 and the electron injection layer 107 are each formed by laminating or mixing one or more types of electron transport / injection materials, or by a mixture of an electron transport / injection material and a polymer binder.

[0330] The electron injection / transport layer is a layer that is responsible for injecting electrons from the cathode and transporting the electrons. It is desirable that the electron injection efficiency is high and that the injected electrons are efficiently transported. For this purpose, it is preferable that the material has a large electron affinity, a large electron mobility, and excellent stability, and impurities that become traps are unlikely to occur during manufacture and use. However, when considering the balance of transport of holes and electrons, if the material mainly plays a role of efficiently preventing holes from flowing from the anode to the cathode without recombining, even if the electron transport ability is not so high, it has the effect of improving the luminous efficiency equivalent to a material with a high electron transport ability. Therefore, the electron injection / transport layer in this embodiment may also include the function of a layer that can efficiently block the movement of holes.

[0331] The material (electron transport material) forming the electron transport layer 106 or the electron injection layer 107 can be arbitrarily selected from compounds conventionally used as electron transport compounds in photoconductive materials and known compounds used in the electron injection layer and electron transport layer of organic EL devices. It is also preferable to use the polycyclic aromatic compound of the present invention as a material for the electron transport layer.

[0332] Materials used in the electron transport layer or electron injection layer preferably contain at least one selected from compounds consisting of aromatic rings or heteroaromatic rings composed of one or more atoms selected from carbon, hydrogen, oxygen, sulfur, silicon, and phosphorus, pyrrole derivatives and their condensed ring derivatives, and metal complexes having electron-accepting nitrogen. Specific examples include condensed ring aromatic ring derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives such as 4,4'-bis(diphenylethenyl)biphenyl, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, arylnitrile derivatives, and indole derivatives. Examples of metal complexes having electron-accepting nitrogen include hydroxyazole complexes such as hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes. These materials can be used alone or in combination with different materials.

[0333] Specific examples of other electron transport compounds include pyridine derivatives, naphthalene derivatives, anthracene derivatives, phenanthroline derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, anthraquinone derivatives, diphenoquinone derivatives, diphenylquinone derivatives, perylene derivatives, oxadiazole derivatives (e.g., 1,3-bis[(4-t-butylphenyl)1,3,4-oxadiazolyl]phenylene), thiophene derivatives, triazole derivatives (e.g., N-naphthyl-2,5-diphenyl-1,3,4-triazole), thiadiazole derivatives, metal complexes of oxine derivatives, quinolinol-based metal complexes, quinoxaline derivatives, polymers of quinoxaline derivatives, benzazole compounds, gallium complexes, pyrazole derivatives, perfluorinated phenylene derivatives, triazine derivatives, pyrazole derivatives, pyridine ... Examples of the compound include quinazine derivatives, benzoquinoline derivatives (e.g., 2,2'-bis(benzo[h]quinolin-2-yl)-9,9'-spirobifluorene), imidazopyridine derivatives, borane derivatives, benzimidazole derivatives (e.g., tris(N-phenylbenzimidazol-2-yl)benzene), benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, oligopyridine derivatives such as terpyridine, bipyridine derivatives, terpyridine derivatives (e.g., 1,3-bis(2,2':6',2"-terpyridine-4'-yl)benzene), naphthyridine derivatives (e.g., bis(1-naphthyl)-4-(1,8-naphthyridine-2-yl)phenylphosphine oxide), aldazine derivatives, carbazole derivatives, indole derivatives, phosphorus oxide derivatives, and bisstyryl derivatives.

[0334] Further, a metal complex having an electron-accepting nitrogen can also be used, and examples thereof include hydroxyazole complexes such as quinolinol metal complexes and hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes.

[0335] The above-mentioned materials may be used alone or in combination with different materials.

[0336] Among the above-mentioned materials, borane derivatives, pyridine derivatives, fluoranthene derivatives, BO-based derivatives, anthracene derivatives, benzofluorene derivatives, phosphine oxide derivatives, pyrimidine derivatives, arylnitrile derivatives, triazine derivatives, benzimidazole derivatives, phenanthroline derivatives, and quinolinol-based metal complexes are preferable.

[0337] The electron transport layer or the electron injection layer may further contain a substance capable of reducing the material forming the electron transport layer or the electron injection layer. As the reducing substance, various substances can be used as long as they have a certain degree of reducing ability, and for example, at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals, oxides of alkali metals, halides of alkali metals, oxides of alkaline earth metals, halides of alkaline earth metals, oxides of rare earth metals, halides of rare earth metals, organic complexes of alkali metals, organic complexes of alkaline earth metals, and organic complexes of rare earth metals can be suitably used.

[0338] Preferred reducing substances include alkali metals such as Na (work function 2.36 eV), K (2.28 eV), Rb (2.16 eV) or Cs (1.95 eV) and alkaline earth metals such as Ca (2.9 eV), Sr (2.0 to 2.5 eV) or Ba (2.52 eV), and substances with a work function of 2.9 eV or less are particularly preferred. Among these, more preferred reducing substances are alkali metals such as K, Rb or Cs, more preferably Rb or Cs, and most preferably Cs. These alkali metals have particularly high reducing ability, and by adding a relatively small amount to the material forming the electron transport layer or electron injection layer, the luminance of the organic EL element can be improved and the life can be extended. Furthermore, as a reducing substance having a work function of 2.9 eV or less, a combination of two or more of these alkali metals is also preferred, and in particular, a combination containing Cs is preferred, for example, a combination of Cs and Na, Cs and K, Cs and Rb, or a combination of Cs, Na and K. By containing Cs, the reducing ability can be efficiently exhibited, and by adding it to a material forming an electron transport layer or an electron injection layer, the luminance of the organic EL element can be improved and the life span can be extended.

[0339] 3-7. Cathode in organic electroluminescent device The cathode 108 serves to inject electrons into the light-emitting layer 105 through the electron injection layer 107 and the electron transport layer 106 .

[0340] The material for forming the cathode 108 is not particularly limited as long as it is a substance that can efficiently inject electrons into the organic layer, but the same material as the material for forming the anode 102 can be used. Among them, metals such as tin, indium, calcium, aluminum, silver, copper, nickel, chromium, gold, platinum, iron, zinc, lithium, sodium, potassium, cesium, and magnesium, or alloys thereof (magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy such as lithium fluoride / aluminum, etc.), etc. are preferable. In order to increase the electron injection efficiency and improve the device characteristics, lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective. However, these low work function metals are generally unstable in the air. To improve this point, for example, a method is known in which a trace amount of lithium, cesium, or magnesium is doped into the organic layer to use a highly stable electrode. As other dopants, inorganic salts such as lithium fluoride, cesium fluoride, lithium oxide, and cesium oxide can also be used. However, they are not limited to these.

[0341] Further, for electrode protection, preferred examples include lamination of metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys using these metals, inorganic substances such as silica, titania, and silicon nitride, polyvinyl alcohol, vinyl chloride, hydrocarbon polymer compounds, etc. The method of producing these electrodes is also not particularly limited as long as it can provide electrical continuity, and may be resistance heating, electron beam deposition, sputtering, ion plating, coating, or the like.

[0342] 3-8. Method for producing organic electroluminescent device Each layer constituting an organic EL element can be formed by forming the material to be formed into a thin film by a method such as vapor deposition, resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination, printing, spin coating or casting, coating, etc. The thickness of each layer thus formed is not particularly limited and can be set appropriately according to the properties of the material, but is usually in the range of 2 nm to 5000 nm. The thickness of the film can usually be measured with a quartz crystal oscillation type film thickness measuring device, etc. When forming a thin film by vapor deposition, the vapor deposition conditions vary depending on the type of material, the desired crystal structure and association structure of the film, etc. The vapor deposition conditions are generally a boat heating temperature of +50 to +400°C, a vacuum degree of 10, and a vacuum of 10. -6 ~10 -3 It is preferable to appropriately set the pressure, pressure Pa, deposition rate 0.01 to 50 nm / sec, substrate temperature -150 to +300°C, and film thickness 2 nm to 5 µm.

[0343] When applying a DC voltage to the organic EL element obtained in this way, the anode should be set to + and the cathode to -. When a voltage of about 2 to 40 V is applied, light emission can be observed from the transparent or semi-transparent electrode side (anode or cathode, or both). This organic EL element also emits light when a pulse current or an AC current is applied. The waveform of the AC current applied may be any waveform.

[0344] Next, as an example of a method for producing an organic EL element, a method for producing an organic EL element consisting of an anode, a hole injection layer, a hole transport layer, an emitting layer consisting of a host material and a dopant material, an electron transport layer, an electron injection layer, and a cathode will be described.

[0345] <Vapor deposition method> A thin film of an anode material is formed on a suitable substrate by vapor deposition or the like to prepare an anode, and then a thin film of a hole injection layer and a hole transport layer is formed on the anode. A host material and a dopant material are co-deposited on the anode to form a thin film as a light-emitting layer, an electron transport layer and an electron injection layer are formed on the light-emitting layer, and a thin film of a cathode material is further formed by vapor deposition or the like to prepare a cathode, thereby obtaining a desired organic EL device. Note that in the preparation of the above-mentioned organic EL device, the preparation order can also be reversed, and the layers can be prepared in the order of cathode, electron injection layer, electron transport layer, light-emitting layer, hole transport layer, hole injection layer, and anode.

[0346] <Wet film formation method> The wet film formation method is carried out by preparing a low molecular weight compound capable of forming each organic layer of an organic EL element as a liquid composition for forming an organic layer, and using this. If there is no suitable organic solvent for dissolving this low molecular weight compound, the composition for forming an organic layer may be prepared from a polymer compound polymerized together with other monomers having a solubility function as a reactive compound obtained by substituting a reactive substituent on the low molecular weight compound or a main chain polymer.

[0347] In the wet film formation method, a coating film is generally formed through a coating step of coating a substrate with a composition for forming an organic layer and a drying step of removing the solvent from the coated composition for forming an organic layer. When the polymer compound has a crosslinkable substituent (also called a crosslinkable polymer compound), the polymer is further crosslinked by the drying step to form a crosslinked polymer. Depending on the difference in the coating step, a method using a spin coater is called a spin coat method, a method using a slit coater is called a slit coat method, a method using a plate is called a gravure, offset, reverse offset, or flexographic printing method, a method using an inkjet printer is called an inkjet method, and a method spraying in a mist form is called a spray method. The drying step includes air drying, heating, drying under reduced pressure, and the like. The drying step may be performed only once, or may be performed multiple times using different methods or conditions. In addition, different methods may be used in combination, such as baking under reduced pressure.

[0348] The wet film formation method is a film formation method using a solution, for example, some printing methods (inkjet methods), spin coating methods or casting methods, coating methods, etc. Unlike the vacuum deposition method, the wet film formation method does not require the use of expensive vacuum deposition equipment, and can form a film under atmospheric pressure. In addition, the wet film formation method allows for large area and continuous production, which leads to reduced manufacturing costs.

[0349] On the other hand, compared to the vacuum deposition method, wet film formation can be difficult to laminate. When producing laminated films using the wet film formation method, it is necessary to prevent the dissolution of the lower layer by the composition of the upper layer, and compositions with controlled solubility, crosslinking of the lower layer, and orthogonal solvents (solvents that do not dissolve in each other) are used. However, even with these technologies, it can be difficult to use the wet film formation method to apply all films.

[0350] Therefore, a method is generally adopted in which only some layers are formed by a wet film formation method and the remaining layers are formed by a vacuum deposition method when manufacturing an organic EL element.

[0351] For example, the procedure for producing an organic EL element by partially applying a wet film formation method will be described below. (Step 1) Formation of the anode by vacuum deposition (Step 2) Forming a film by a wet film formation method using a composition for forming a hole injection layer containing a material for the hole injection layer (Step 3) Forming a film by a wet film formation method using a composition for forming a hole transport layer containing a material for the hole transport layer (Step 4) Formation of a film by a wet film formation method using a composition for forming an emitting layer containing a host material and a dopant material (Step 5) Formation of the electron transport layer by vacuum deposition (Step 6) Formation of the electron injection layer by vacuum deposition (Step 7) Cathode deposition by vacuum deposition Through this procedure, an organic EL element consisting of an anode, a hole injection layer, a hole transport layer, an emitting layer made of a host material and a dopant material, an electron transport layer, an electron injection layer, and a cathode is obtained. Of course, the electron transport layer and the electron injection layer may also be formed by a wet film formation method using a layer-forming composition containing the material for the electron transport layer and the material for the electron injection layer, respectively. In this case, it is preferable to use a means for preventing dissolution of the lower light-emitting layer, or a means for forming the film from the cathode side in the reverse order to the above procedure.

[0352] <Other film formation methods> The composition for forming an organic layer can be formed into a film by laser thermal imaging (LITI). LITI is a method in which a compound attached to a substrate is heated and evaporated by a laser, and the composition for forming an organic layer can be used as the material applied to the substrate.

[0353] <Optional process> Before and after each film-forming step, appropriate treatment steps, cleaning steps, and drying steps may be appropriately inserted. Examples of treatment steps include exposure treatment, plasma surface treatment, ultrasonic treatment, ozone treatment, cleaning treatment using an appropriate solvent, and heat treatment. Furthermore, a series of steps for preparing a bank may also be included.

[0354] Photolithography techniques can be used to fabricate the banks. Positive resist materials and negative resist materials can be used as bank materials that can be used in photolithography. In addition, patternable printing methods such as inkjet printing, gravure offset printing, reverse offset printing, and screen printing can also be used. In this case, permanent resist materials can also be used.

[0355] <Composition for forming organic layer used in wet film formation method> The composition for forming an organic layer is obtained by dissolving a low molecular weight compound capable of forming each organic layer of an organic EL device, or a polymer compound obtained by polymerizing the low molecular weight compound, in an organic solvent. For example, the composition for forming an emitting layer contains at least one polycyclic aromatic compound (or a polymer compound thereof) as a first component, which is a dopant material, at least one host material as a second component, and at least one organic solvent as a third component. The first component functions as a dopant component of the emitting layer obtained from the composition, and the second component functions as a host component of the emitting layer. The third component functions as a solvent that dissolves the first and second components in the composition, and gives a smooth and uniform surface shape due to the controlled evaporation rate of the third component itself during application.

[0356] <Organic solvent> The organic layer forming composition contains at least one organic solvent. By controlling the evaporation rate of the organic solvent during film formation, it is possible to control and improve the film forming properties, the presence or absence of defects in the coating film, the surface roughness, and the smoothness. In addition, during film formation using the inkjet method, it is possible to control the meniscus stability at the pinhole of the inkjet head, and control and improve the ejection properties. In addition, by controlling the drying rate of the film and the orientation of the derivative molecules, it is possible to improve the electrical properties, light emitting properties, efficiency, and life of an organic EL element having an organic layer obtained from the organic layer forming composition.

[0357] After the film is formed, the organic solvent is removed from the coating film by a drying process such as vacuum, reduced pressure, or heating. When heating is performed, from the viewpoint of improving the coating film-forming property, it is preferable to perform the heating at a temperature of at least one of the solutes at a glass transition temperature (Tg) +30°C or lower. From the viewpoint of reducing the residual solvent, it is preferable to heat at at least one of the solutes at a glass transition temperature (Tg) -30°C or higher. Even if the heating temperature is lower than the boiling point of the organic solvent, the organic solvent is sufficiently removed because the film is thin. Also, drying may be performed multiple times at different temperatures, and multiple drying methods may be used in combination.

[0358] (2) Specific examples of organic solvents Examples of organic solvents used in the organic layer-forming composition include, but are not limited to, alkylbenzene solvents, phenyl ether solvents, alkyl ether solvents, cyclic ketone solvents, aliphatic ketone solvents, monocyclic ketone solvents, solvents having a diester skeleton, and fluorine-containing solvents. The solvents may be used alone or in combination.

[0359] <Optional ingredients> The composition for forming the organic layer may contain optional components, such as a binder and a surfactant, to the extent that the properties of the composition are not impaired.

[0360] <Composition and Properties of the Organic Layer-Forming Composition> The content of each component in the composition for forming an organic layer is determined taking into consideration good solubility, storage stability, and film-formability of each component in the composition for forming an organic layer, as well as good film quality of a coating film obtained from the composition for forming an organic layer, good ejection properties when an inkjet method is used, and good electrical characteristics, light-emitting characteristics, efficiency, and life of an organic EL element having an organic layer produced using the composition.

[0361] The composition for forming an organic layer can be produced by appropriately selecting the above-mentioned components and subjecting them to stirring, mixing, heating, cooling, dissolving, dispersing, etc., by a known method. After preparation, filtration, degassing (also called degassing), ion exchange treatment, and inert gas replacement / filling treatment, etc. may be appropriately selected.

[0362] <Applications of organic electroluminescent devices> The present invention can also be applied to a display device having an organic EL element or a lighting device having an organic EL element. A display device or lighting device including an organic EL element can be manufactured by a known method, for example by connecting the organic EL element according to this embodiment to a known driving device, and can be driven appropriately using a known driving method such as DC driving, pulse driving, or AC driving.

[0363] Examples of the display device include panel displays such as color flat panel displays, and flexible displays such as flexible color organic electroluminescent (EL) displays (see, for example, JP-A-10-335066, JP-A-2003-321546, JP-A-2004-281086, etc.). Examples of the display method include matrix and segment methods. Note that matrix display and segment display may coexist in the same panel.

[0364] In a matrix, pixels for display are arranged two-dimensionally, such as in a grid or mosaic pattern, and a collection of pixels displays characters and images. The shape and size of the pixels are determined by the application. For example, square pixels with sides of 300 μm or less are usually used to display images and characters on computers, monitors, and televisions, and pixels with sides of mm order are used for large displays such as display panels. For monochrome display, pixels of the same color are arranged, but for color display, red, green, and blue pixels are displayed side by side. In this case, there are typically delta type and stripe type. The driving method for this matrix can be either line sequential driving method or active matrix. Line sequential driving has the advantage of being simpler in structure, but when considering the operating characteristics, active matrix may be superior, so it is necessary to use it according to the application.

[0365] In the segment type, a pattern is formed to display predetermined information, and a predetermined area is illuminated. Examples include time and temperature displays in digital clocks and thermometers, operating status displays in audio equipment and induction cookers, and panel displays in automobiles.

[0366] Examples of the lighting device include lighting devices for indoor lighting, backlights for liquid crystal display devices, etc. (see, for example, JP 2003-257621 A, JP 2003-277741 A, JP 2004-119211 A, etc.). Backlights are mainly used for the purpose of improving the visibility of non-self-luminous display devices, and are used in liquid crystal display devices, clocks, audio devices, automobile panels, display boards, signs, etc. In particular, for liquid crystal display devices, particularly backlights for personal computers, where thinning is an issue, it is difficult to make them thin because conventional methods are made of fluorescent lamps and light guide plates, so the backlight using the light-emitting element according to this embodiment is characterized by its thinness and light weight.

[0367] 4. Other organic devices The polycyclic aromatic compound according to the present invention can be used for producing the above-mentioned organic electroluminescent device, as well as an organic field effect transistor or an organic thin-film solar cell. EXAMPLES

[0368] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0369] <<Synthesis example>> Synthesis example (1): Synthesis of compound (1-1) [ka]

[0370] A 1.6M tert-butyllithium pentane solution (1.6ml) was added to a flask containing compound (S-1-1) (0.72g) and tert-butylbenzene (7.0ml) under a nitrogen atmosphere at -30°C. After the dropwise addition, the temperature was raised to 60°C and stirred for 2 hours, and then components with a boiling point lower than that of tert-butylbenzene were distilled off under reduced pressure. The mixture was cooled to -30°C, boron tribromide (0.63g) was added, the mixture was heated to room temperature and stirred for 0.5 hours. Then, the mixture was cooled again to 0°C, N,N-diisopropylethylamine (0.43ml) was added, and the mixture was stirred at room temperature until the heat generation subsided, and then the mixture was heated to 120°C and stirred for 3 hours. The reaction solution was cooled to room temperature, and an aqueous sodium acetate solution cooled in an ice bath was added, followed by heptane, and the mixture was separated. Next, the residue was purified using a silica gel short-path column (eluent: toluene), and the solvent was distilled off under reduced pressure. The resulting solid was dissolved in toluene and reprecipitated by adding heptane to obtain compound (1-1) (0.37 g).

[0371] The following compounds were synthesized according to the method of Synthesis Example (1). [ka]

[0372] [ka]

[0373] The above compounds (1-286) to (1-494) were further synthesized in a similar manner to Synthesis Example (1).

[0374] The production of the target substance was confirmed by MALDI-TOF-MS (matrix-assisted laser desorption / ionization time-of-flight mass spectrometry). [Table 1] TIFF2024178904000126.tif231170TIFF2024178904000127.tif227170TIFF2024178904000128.tif228170TIFF2024178904000129.tif212170

[0375] <<Manufacture and Evaluation of Organic EL Devices>> Using each of the synthesized compounds of the present invention and comparative compounds, each of the TAF and PSF organic EL devices was manufactured.

[0376] <TADF Configuration: Examples 1-1 to 1-19 and Comparative Example 1-1> ITO(50nm) / HAT-CN(10nm) / HT-1(60nm) / SiCzCz(5nm) / SiCzCz: Each compound described in Table 2: new-DABNA(60:39:1)(35nm) / mSiTrz(5nm) / mSiTrz:Liq(1:1)(30nm) / LiF(1nm) / Al(100nm) An ITO film formed to a thickness of 200 nm by sputtering was polished to 50 nm, and a 26 mm × 28 mm × 0.7 mm glass substrate (manufactured by Opto Science Co., Ltd.) was used as a transparent support substrate. This transparent support substrate was fixed to the substrate holder of a commercially available vapor deposition apparatus (manufactured by Showa Vacuum Co., Ltd.), and molybdenum vapor deposition boats containing HAT-CN, HT-1, SiCzCz, each compound described in Table 2, new-DABNA, mSiTrz, and Liq, and tungsten vapor deposition boats containing LiF and aluminum were mounted.

[0377] The following layers were sequentially formed on the ITO film of the transparent support substrate. The vacuum chamber was 5×10 -4The pressure was reduced to Pa. First, HAT-CN was heated and vapor-deposited to a thickness of 10 nm to form a hole injection layer. Next, HT-1 was heated and vapor-deposited to a thickness of 60 nm to form a hole transport layer 1. Further, SiCzCz was heated and vapor-deposited to a thickness of 5 nm to form a hole transport layer 2. Next, SiCzCz, each compound described in Table 2, and new-DABNA were simultaneously heated and vapor-deposited to a thickness of 35 nm to form a light-emitting layer. The deposition rate was adjusted so that the mass ratio of SiCzCz, each compound described in Table 2, and new-DABNA was approximately 60:39:1. Next, mSiTrz was heated and vapor-deposited to a thickness of 5 nm to form an electron transport layer 1. Further, mSiTrz and Liq were heated and vapor-deposited to a thickness of 30 nm to form an electron transport layer 2. The deposition rate was adjusted so that the mass ratio of SiTrz and Liq was approximately 1:1. The deposition rate of each layer was 0.01 - 1 nm / second. Thereafter, LiF was heated and vapor-deposited at a deposition rate of 0.01 - 0.1 nm / second to a thickness of 1 nm. Then, aluminum was heated and vapor-deposited to a thickness of 100 nm to form a cathode, and an organic EL element was obtained. At this time, the deposition rate of aluminum was adjusted to be 1 - 10 nm / second. Note that SiCzCz in the light-emitting layer corresponds to a hole-transporting host material, and each compound described in Table 2 corresponds to an electron-transporting host material.

[0378] <TAF Configuration: Examples 2-1 to 2-19 and Comparative Example 2-1> ITO(50 nm) / HAT-CN(10 nm) / HT-1(60 nm) / SiCzCz(5 nm) / SiCzCz: Each compound described in Table 2: TADF-1: new-DABNA(60:26:13:1)(35 nm) / mSiTrz(5 nm) / mSiTrz:Liq(1:1)(30 nm) / LiF(1 nm) / Al(100 nm) Except for the light-emitting layer, it was fabricated in the same manner as the TADF configuration. In the light-emitting layer, SiCzCz, each compound described in Table 2, (TADF-1), and new-DABNA were simultaneously heated and vapor-deposited to a thickness of 35 nm. The deposition rate was adjusted so that the mass ratio of SiCzCz, each compound described in Table 2, (TADF-1), and new-DABNA was approximately 60:26:13:1.

[0379] <PSF Structure: Examples 3-1 to 3-228 and Comparative Example 3-1> ITO (50 nm) / HAT-CN (10 nm) / HT-1 (60 nm) / SiCzCz (5 nm) / SiCzCz: Each compound described in Table 2: PtON7: new-DABNA (60:26:13:1) (35 nm) / mSiTrz (5 nm) / mSiTrz:Liq (1:1) (30 nm) / LiF (1 nm) / Al (100 nm) The (TADF-1) of the above TAF structure was replaced with PtON7, and the device was fabricated in the same manner.

[0380] The chemical structures of the compounds used in the manufacture of the above devices are shown below. [Chemical Formula]

[0381] [Evaluation] Evaluation items include driving voltage (V), emission wavelength (nm), CIE chromaticity (x, y), external quantum efficiency (%), maximum wavelength (nm) and full width at half maximum (nm) of the emission spectrum, etc. These evaluation items can use the values during emission, for example, at 1000 cd / m 2 The values during emission can be used.

[0382] The quantum efficiency of a light-emitting device includes internal quantum efficiency and external quantum efficiency. The internal quantum efficiency indicates the ratio at which the external energy injected as electrons (or holes) into the light-emitting layer of the light-emitting device is purely converted into photons. On the other hand, the external quantum efficiency is calculated based on the amount of photons emitted to the outside of the light-emitting device. Since some of the photons generated in the light-emitting layer are absorbed or continuously reflected inside the light-emitting device and are not emitted to the outside of the light-emitting device, the external quantum efficiency is lower than the internal quantum efficiency.

[0383] The measurement methods for spectral radiance (emission spectrum) and external quantum efficiency are as follows. Using a voltage / current generator R6144 manufactured by Advantest Corporation, when the luminance of the device is 1000 cd / m 2The device emits light by applying a voltage that is equal to the wavelength of the light emitted by the device. The spectral radiance of the visible light region is measured from a direction perpendicular to the light-emitting surface using a TOPCON SR-3AR spectroradiometer. Assuming that the light-emitting surface is a perfect diffusing surface, the measured spectral radiance value of each wavelength component is divided by the wavelength energy and multiplied by π to obtain the number of photons at each wavelength. The number of photons is then integrated over the entire wavelength range observed to obtain the total number of photons emitted from the device. The applied current value is divided by the elementary charge to obtain the number of carriers injected into the device, and the total number of photons emitted from the device is divided by the number of carriers injected into the device to obtain the external quantum efficiency. The half-width of the emission spectrum is calculated as the width between the wavelengths above and below where the intensity is 50% of the maximum emission wavelength.

[0384] A DC voltage of 1000 cd / m was applied to the ITO electrode as the anode and the LiF / aluminum electrode as the cathode. 2 The characteristics of the device during emission were measured. The time (lifetime) during which the device maintained 50% or more of the initial luminance was also measured. The emission peaks of the devices were all in the range of 469 to 475 nm. The results are shown in Table 2.

[0385] [Table 2] TIFF2024178904000132.tif231170TIFF2024178904000133.tif227170TIFF2024178904000134.tif23017 0TIFF2024178904000135.tif228170TIFF2024178904000136.tif228170TIFF2024178904000137.tif51170

[0386] The results show that the element of the embodiment has higher efficiency and longer life than the element of the comparative example having the corresponding skeleton. [Explanation of symbols]

[0387] 100 Organic electroluminescent device 101 Substrate 102 Anode 103 Hole injection layer 104 Hole transport layer 105 Light-emitting layer 106 Electron transport layer 107 Electron injection layer 108 Cathode

Claims

1. A polycyclic aromatic compound represented by formula (1) and containing at least one partial structure represented by formula (X-a-1) and at least one partial structure represented by formula (X-b-1); 【Chemistry 1】 In formula (1), ring A, ring B, and ring C each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; In formula (Xa-1), X a is C, Si, Ge, or Sn; ring AR1, ring AR2, ring AR3, and ring AR4 each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and ring AR1, ring AR2, ring AR3, and ring AR4 each may be linked to any other ring AR1, ring AR2, ring AR3, and ring AR4 via a single bond or a linking group; One or two selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 are is bonded via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; It is bonded to ring A, ring B, or ring C, or is bonded via a single bond to an atom constituting a ring of an aryl ring or heteroaryl ring of ring D, ring E, or ring AR5 in formula (X-b-1) which shares any ring with ring A, ring B, or ring C; Shares a ring with ring A, ring B, or ring C, or It is bonded to ring A, ring B, or ring C, or shares a ring with ring D, ring E, or ring AR5 in formula (X-b-1) which shares any ring with ring A, ring B, or ring C, In formula (X-b-1), ring D and ring E are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring; X b represents a divalent group represented by formula (Xb-R5), >O, or >S, 【Chemistry 2】 In formula (Xb-R5), The two #'s indicate the bonding positions with the D and E rings, respectively. ring AR5 is a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and ring AR5 may be linked to ring D and / or ring E via a single bond or a linking group; One or two selected from the group consisting of ring D, ring E, and ring AR5 are is bonded via a single bond to an atom of an aryl or heteroaryl ring in ring A, ring B, or ring C; is bonded to ring A, ring B or ring C, or is bonded via a single bond to a ring-constituting atom of an aryl ring or heteroaryl ring in ring AR1, ring AR2, ring AR3 or ring AR4 in formula (X-a-1) which shares any ring with ring A, ring B or ring C; Shares a ring with ring A, ring B, or ring C, or it is bonded to ring A, ring B, or ring C, or shares a ring with ring AR1, ring AR2, ring AR3, or ring AR4 in formula (X-a-1), which shares any ring with ring A, ring B, or ring C; In formula (1), at least one hydrogen may be replaced with a deuterium, and at least one nitrogen may be replaced with a nitrogen-15 ( 15 N), and at least one sulfur may be replaced by sulfur-33 ( 33 S), Sulfur-34 ( 34 S) or sulfur-36 ( 36 S), and at least one oxygen may be replaced by oxygen-17 ( 17 O) or oxygen-18 ( 18 O), and at least one carbon may be replaced by carbon-13 ( 13 C), and at least one boron may be replaced by boron-11 ( 11 B) may be substituted.

2. The polycyclic aromatic compound according to claim 1, wherein at least one selected from the group consisting of ring AR1, ring AR2, ring AR3, and ring AR4 shares a ring with ring A, ring B, or ring C, or ring D, ring E, or ring AR5 in formula (X-b-1) which is bonded to ring A, ring B, or ring C.

3. The polycyclic aromatic compound according to claim 1, which is represented by formula (1a), formula (1b), or formula (1c) and contains at least one partial structure represented by formula (X-a-2) and at least one partial structure represented by formula (X-b-2); 【Chemistry 3】 In formula (1a), formula (1b), formula (1c), formula (X-a-2), and formula (X-b-2), Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 One or two selected from the group consisting of rings are is bonded to Z in ring a, ring b, or ring c via a single bond; It is bonded to ring d, ring e, or ring AR5 in the partial structure represented by formula (X-b-2) which is bonded to Z in ring a, ring b, or ring c, or sharing a ring with ring a, ring b, or ring c; or It is bonded to ring a, ring b, or ring c, or shares a ring with ring d, ring e, or ring AR5 in formula (X-b-2) which shares any ring with ring a, ring b, or ring c, One or two selected from the group consisting of ring d, ring e, and ring AR5 are is bonded to Z in ring a, ring b, or ring c via a single bond; Ar in the partial structure represented by formula (X-a-2) bonded to Z in ring a, ring b, or ring c 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 attached to Z in the ring, sharing a ring with ring a, ring b, or ring c; or Ar in formula (X-a-2) is bonded to ring a, ring b, or ring c, or shares any ring with ring a, ring b, or ring c. 1 Ring, Ar 2 Ring, Ar 3 Ring, or Ar 4 They share rings, Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 Each ring is another Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 may be linked to any one of the rings via a single bond or a linking group, Y 1 and Y 2 are each independently >N-R NY , >C(-R CY ) 2 , >O, >Si(-R IY ) 2 , >S, or >Se; R NY , R CY , and R IY are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CY may be bonded to each other to form a ring, and two R IY may be bonded to each other to form a ring, Z is a carbon atom having a bond to another ring or -C(-R Z )= or -N=, and R Z is a hydrogen atom or a substituent, provided that adjacent two of Z constituting the e ring in formula (X-b-2) may be carbon atoms bonded to the two * in formula (X-b-2-e), and in formula (X-b-2-e), b is a divalent group represented by the formula (Xb-R5), >O, >C(-R CX ) 2 , >Si(-R IX ) 2 , >S, or >Se; R CX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; CX may be bonded to each other to form a ring, R IX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; IX may be bonded to each other to form a ring, X b When is a divalent group represented by the formula (XB-R5), the AR5 ring is a 6-membered ring.

4. The polycyclic aromatic compound according to claim 3 , which is represented by formula (1b) or formula (1c):

5. In formula (X-a-2), X a is C, Ge, or Sn, and Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 4. The polycyclic aromatic compound of claim 3, wherein no two of the rings are linked to each other.

6. In formula (X-a-2), X a is Si and at least one of Z is -N=.

7. In formula (X-a-2), X a is Si, and Ar 1 Ring, Ar 2 Ring, Ar 3 ring, and Ar 4 The polycyclic aromatic compound of claim 3 , wherein at least two of the rings are linked to each other.

8. The polycyclic aromatic compound according to claim 3, wherein in formula (X-b-2), at least one Z is -N=.

9. The polycyclic aromatic compound according to claim 3, which is represented by any one of the following formulas: 【Chemistry 4】 【Chemistry 5】

10. The polycyclic aromatic compound according to claim 3, which is represented by any one of the following formulas: 【Chemistry 6】 【Chemistry 7】 【Chemistry 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 【Chemistry 17】 【Chemistry 18】

11. The polycyclic aromatic compound according to claim 3, which is represented by any one of the following formulas: 【Chemistry 19】

12. 12. An organic electroluminescence device comprising a pair of electrodes consisting of an anode and a cathode, and an organic layer disposed between the pair of electrodes, the organic layer containing the polycyclic aromatic compound according to claim 1.

13. The organic electroluminescent device according to claim 12 , wherein the organic layer is a light-emitting layer.

14. 14. The organic electroluminescent device according to claim 13, wherein the polycyclic aromatic compound is an electron transporting host material, and the light emitting layer further comprises a hole transporting host material and a dopant material.

15. The organic electroluminescent device according to claim 14, wherein the light-emitting layer further comprises at least one selected from the group consisting of a thermally activated delayed fluorescent material and a phosphorescent material.

16. A display device or a lighting device comprising the organic electroluminescent device according to claim 12.

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