Organic electroluminescent element

Abstract

Provided are: a material and a mixed composition for low-voltage and highly efficient organic electroluminescent elements that are practically useful and have long lifetime characteristics; and an organic electroluminescent elements using the same.　The material for organic electroluminescent elements is represented by any of general formulae (1)-(4). (Ar1 and Ar2 are each independently a substituted or unsubstituted C6-C18 aromatic hydrocarbon group or the like; R1 to R4 are each independently hydrogen, deuterium, or the like; X is selected from any of O, S, N-Ar3; and Ar3 is a substituted or unsubstituted C6-C18 aromatic heterocyclic group or the like. "a" to "d" are each the number of substitutions, with "a" and "d" each being an integer of 1 to 4 and "b" and "c" being the integer 1 or 2.)

Description

Organic electroluminescent device

[0001] The present invention relates to an organic electroluminescent device (hereinafter referred to as an organic EL device), and more particularly to an organic EL device containing a specific mixed host material.

[0002] When a voltage is applied to an organic EL element, holes are injected from the anode and electrons are injected from the cathode into the light-emitting layer. The injected holes and electrons then recombine in the light-emitting layer, generating excitons. At this time, due to the statistical law of electron spin, singlet excitons and triplet excitons are generated in a ratio of 1:3. It is said that the internal quantum efficiency of fluorescent organic EL elements that use emission from singlet excitons is limited to 25%. On the other hand, it is known that the internal quantum efficiency of phosphorescent organic EL elements that use emission from triplet excitons can be increased to 100% if intersystem crossing from singlet excitons is efficiently performed.

[0003] Recently, highly efficient organic EL devices utilizing delayed fluorescence have been developed. For example, Patent Document 1 discloses an organic EL device utilizing the TTF (Triplet-Triplet Fusion) mechanism, which is one of the mechanisms of delayed fluorescence. The TTF mechanism utilizes the phenomenon in which singlet excitons are generated by the collision of two triplet excitons, and is thought to theoretically increase the internal quantum efficiency to 40%. However, since the efficiency is lower than that of phosphorescent organic EL devices, further improvements in efficiency and low-voltage characteristics are required.

[0004] Furthermore, Patent Document 2 discloses an organic EL device utilizing the TADF (Thermally Activated Delayed Fluorescence) mechanism. The TADF mechanism utilizes the phenomenon of reverse intersystem crossing from triplet excitons to singlet excitons in a material with a small energy difference between the singlet and triplet levels, and is believed to theoretically increase the internal quantum efficiency to 100%.

[0005] However, in both mechanisms, there is room for improvement in both efficiency and lifespan, and there is also a demand for improvements in reducing the driving voltage.

[0006] WO2010 / 134350 WO2011 / 070963 Korean Patent Publication No. 2015-0095186 Korean Patent Publication No. 20110016288 WO2011 / 019173 WO2014 / 057684 WO2018 / 043435 Korean Patent No. 101959821 WO2015 / 169412 Korean Patent Publication No. 20140097044 Korean Patent Publication No. 20160146619

[0007] Patent Documents 3, 4, 5 and 6 disclose the use of specific fused ring compounds containing a chalcogen element such as oxygen or sulfur atom and a nitrogen atom as a host material for the light-emitting layer.

[0008] Patent Document 7 discloses the use of a specific fused ring compound containing a chalcogen element such as oxygen or sulfur atom and a nitrogen atom, and a biscarbazole compound as a mixed host material in a light-emitting layer.

[0009] Patent Documents 8 and 9 disclose the use of a specific azine-substituted dibenzofuran compound and a biscarbazole compound as a mixed host material in a light-emitting layer.

[0010] Patent Documents 10 and 11 disclose examples of synthesizing specific fused ring compounds containing nitrogen atoms. However, neither of these methods can be said to be satisfactory, and further improvements are desired.

[0011] Compared to liquid crystal displays, organic EL displays are characterized by their thinness and lightness, high contrast, and ability to display high-speed moving images. They are also highly valued for their design flexibility, such as their curved and flexible surfaces, and are widely used in display devices such as mobile devices and TVs. However, to reduce battery consumption when used in portable terminals, further lower voltages are required. Furthermore, as light sources, organic EL displays are inferior to inorganic LEDs in terms of brightness and lifespan, so improvements in efficiency and device lifespan are required. In view of the above-mentioned current situation, the present invention aims to provide a material for organic electroluminescent devices that can realize practically useful organic EL devices that operate at low voltages, have high efficiency, and have long lifespans.

[0012] As a result of extensive investigations, the present inventors have found that the organic electroluminescent device can solve the above-mentioned problems by using a predetermined host material, particularly a specific mixed host material, in the light-emitting layer, and have thus completed the present invention.

[0013] The present invention provides a material for an organic electroluminescent device represented by any one of the following general formulas (1) to (4).

[0014] In the general formulas (1) to (4), Ar １ and Ar 2 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic groups are linked together. １ and Ar 2 When R is an aromatic heterocyclic group, it is an aromatic group that does not contain a nitrogen-containing six-membered ring. １ ~R 4 each independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic groups are linked together. １ ~R 4 When X is an aromatic hydrocarbon group, it may be condensed with the benzene ring to which it is attached to form a ring. ３ and Ar is selected from 3 represents a substituted or unsubstituted aromatic heterocyclic group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group in which 2 or 3 of these aromatic groups are linked together. a to d represent the number of substitutions, a and d are integers of 1 to 4, and b and c are integers of 1 to 2. However, Ar 3 When is an aromatic heterocyclic group, it is an aromatic group that does not contain a nitrogen-containing six-membered ring.

[0015] In a preferred embodiment of the present invention, the general formulas (1) to (4) satisfy any one of the following conditions (i) to (iii): (i) R １ ~R 4are each independently hydrogen, deuterium, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two such aromatic groups are linked together; (ii) X is O or S; (iii) Ar １ and Ar ２ At least one of the above is a substituted or unsubstituted benzene, carbazole, dibenzofuran, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these are linked together.

[0016] The present invention also relates to an organic electroluminescent device comprising one or more light-emitting layers between opposing anode and cathode, wherein at least one of the light-emitting layers contains a material for organic electroluminescent devices represented by any one of the general formulas (1) to (4). Furthermore, the organic light-emitting device comprises one or more light-emitting layers between opposing anode and cathode, wherein at least one of the light-emitting layers contains a first host selected from the compounds represented by the general formulas (1) to (4), a second host selected from the compounds represented by the following general formula (5), and a light-emitting dopant material. The first host and the second host are different compounds. The compounds represented by the general formulas (1) to (4) are excellent hole-transporting materials and can therefore be used as first hosts (also called hole-transporting hosts).

[0017] In the general formula (5), Ar ４ , Ar ５ , and Ar ６ X each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 7 of these aromatic rings are linked together. 1 ~X 3 each independently represents N or C—H, and at least one is N.

[0018] The compound of the general formula (5) may be represented by the following formula (6) or formula (7): In formula (6) or formula (7), symbols common to general formula (5) have the same meanings.

[0019] In the general formula (6), ring A is a heterocycle represented by the formula (6a) which is fused with two adjacent rings at any position. ７ , Ar ８ , and Ar ９ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together. L is a direct bond, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. R ８ ~R １０ are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. f to h are the number of substitutions, and f and h are integers of 1 to 4, and g is an integer of 1 or 2. X 1 ~X 3 has the same meaning as the general formula (5).

[0020] In the general formula (7), Ar １０ , Ar １１ , and Ar １２ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic rings are linked together. １４ ~R １５ are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. Y is selected from O and S, and m and n are the number of substitutions and are integers of 1 to 3.

[0021] The compound of general formula (6) includes embodiments represented by the following formulas (8) to (11), and is preferably represented by formula (10) or (11). In formulas (8) to (11), symbols common to general formula (6) have the same meanings.

[0022] In the general formula (6) and the general formulas (8) to (11), Ar ９ is a substituted or unsubstituted linking aromatic group formed by linking 2 or 3 of substituted or unsubstituted benzene, pyridine, pyrimidine, triazine, carbazole, dibenzofuran, triphenylene, or any of these.

[0023] The compound of general formula (7) includes embodiments represented by the following formulas (12) to (15), with the embodiment represented by formula (15) being preferred. In formulas (12) to (15), symbols common to general formula (7) have the same meanings.

[0024] In the general formula (7) and the general formulas (12) to (15), Ar １０ is a substituted or unsubstituted linking aromatic group formed by linking 2 or 3 of substituted or unsubstituted benzene, pyridine, pyrimidine, triazine, carbazole, dibenzofuran, triphenylene, or any of these.

[0025] In the organic electroluminescent device of the present invention, the luminescent dopant is preferably an organometallic complex containing at least one metal selected from the group consisting of ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold, or a thermally activated delayed fluorescent dopant.

[0026] The present invention also relates to a mixed composition comprising a first host compound represented by any one of the general formulas (1) to (4) and a second host compound represented by either the general formula (6) or the general formula (7), preferably a mixed composition comprising a first host compound represented by any one of the general formulas (1) to (4) and a second host compound represented by either the general formula (6) or the general formula (7), and more preferably a mixed composition comprising a first host compound represented by any one of the general formulas (1) to (4) and a second host compound represented by either the general formula (11) or the general formula (15). The mixed composition may be in the form of a powder, solid, or thin film, as long as it contains a first host compound represented by any one of the general formulas (1) to (4) and a second host compound represented by either the general formula (6) or the general formula (7). The mixed composition may be prepared by mixing a powder of a host compound containing a first host compound represented by any one of the general formulae (1) to (4) and a second host compound represented by any one of the general formulae (6) and (7), or by melt-mixing the compounds by heating under reduced pressure or in an inert gas atmosphere such as nitrogen, or by sublimating the compounds together. Alternatively, the mixed composition may be prepared as a vapor-deposited film by vapor deposition or the like. The vapor-deposited film may be prepared by simultaneous vaporization from a single evaporation source, or by vaporization from separate evaporation sources. The vapor-deposited film includes a light-emitting layer containing a dopant (light-emitting dopant material).

[0027] Regarding the mixing ratio of the first host and the second host in the mixed composition, whether they are mixed in a powder state, vaporized from separate vapor deposition sources, or in a thin film state, the proportion of the compound represented by any of general formulas (1) to (4) relative to the total of the compound represented by any of general formulas (1) to (4) and the compound represented by general formula (6) or general formula (7) is preferably 10 wt % or more and less than 80 wt %, more preferably 20 wt % or more and less than 70 wt %.

[0028] The present invention also provides an organic electroluminescent device comprising one or more light-emitting layers between opposing anode and cathode electrodes, wherein at least one light-emitting layer comprises a compound represented by any one of general formulas (1) to (4) as a first host, a compound represented by general formula (6) as a first host or general formula (7) as a second host, and a light-emitting dopant material. The method for producing the organic electroluminescent device further comprises the steps of: premixing powders of a compound represented by any one of general formulas (1) to (4) as the first host and a compound represented by general formula (6) or general formula (7) as a second host to form a premixed composition; and then depositing a host material comprising the premixed composition to form a light-emitting layer. In this specification, the term "premixed composition" refers to a mixture of powders of a compound represented by any one of general formulas (1) to (4) as the first host and a compound represented by general formula (6) or general formula (7) as the second host.

[0029] In the mixed composition and the premixed composition, the difference in 50% weight loss temperature between the first host and the second host is preferably within 20°C.

[0030] According to the present invention, by using a predetermined material for an organic electroluminescent device, it is possible to realize a practically useful organic EL device that operates at a low voltage, has high efficiency, and has long life characteristics. Specifically, by using a specific fused heterocyclic compound containing a chalcogen element such as oxygen or sulfur atom and a nitrogen atom as a first host and a specific azine compound as a second host, it is possible to obtain an organic EL device that operates at a low voltage, has high efficiency, and has long life characteristics.

[0031] FIG. 1 is a schematic cross-sectional view showing an example of an organic EL element.

[0032] The material for organic electroluminescent elements of the present invention comprises a compound represented by any one of the general formulas (1) to (4). The compounds represented by the general formulas (1) to (4) can suitably form the following organic electroluminescent elements. That is, the organic electroluminescent element of the present invention is an organic electroluminescent element having multiple organic layers between an anode and a cathode. The organic layers include at least one light-emitting layer, and the light-emitting layer includes a compound represented by any one of the general formulas (1) to (4) (first host), a compound represented by the general formula (5) (second host), and a light-emitting dopant material. The first host and the second host perform different functions of charge injection and transport in the light-emitting layer, with the first host primarily performing hole injection and transport, and the second host primarily performing electron injection and transport. Here, the compound represented by any one of the general formulas (1) to (4) has excellent hole injection and transport ability and is useful as a hole injection and transport host material (also referred to as a P-type host material) for the material for organic electroluminescent elements. Hereinafter, the compounds represented by the general formulas (1) to (4) are also referred to as first hosts, and the compound represented by the general formula (5) is also referred to as second hosts.

[0033] In the general formulas (1) to (4), the common symbols have the same meaning, and the general formulas (1) to (3) are preferred, and the general formula (1) is more preferred. X each independently represents O, S, or N-Ar. ３ and is preferably O or S, and more preferably O.

[0034] Ar １ ~Ar ３ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 aromatic rings of these aromatic groups are linked together. Preferably, they are a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 aromatic hydrocarbon groups are linked together. More preferably, they are a substituted or unsubstituted phenyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted dibenzofuranyl group, or a substituted or unsubstituted linked aromatic group in which 2 or 3 aromatic rings of these aromatic groups are linked together.

[0035] The above Ar １ ~Ar ３ Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, or linked aromatic groups in which 2 or 3 of these aromatic rings are linked together include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, thiophene, isothiazole, thiazole, pyrrole, pyrazole, imidazole, triazole, thiadiazole, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazolidinyl, and the like. Benzimidazole, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, phenoxazine, phenothiazine, acridine, or a group formed by removing hydrogen from a compound formed by linking two or three of these. １ ~Ar ３ is preferably a group derived from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, carbazole, dibenzofuran, or a compound formed by linking two or three of these. More preferably, it is a group derived from benzene, biphenyl, or terphenyl. The terphenyl group may be linearly linked or branched.

[0036] R １ ~R ４are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 3 aromatic rings of an aromatic group selected from these aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together. Preferably, they are hydrogen, deuterium, or a substituted or unsubstituted phenyl group. More preferably, they are hydrogen or deuterium. Also, R １ ~R ４ is an aromatic hydrocarbon group, R １ ~R ４ may be condensed with the benzene ring or aromatic ring to which it is bonded to form a ring.

[0037] R １ ~R ４ is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or an unsubstituted linked aromatic group in which 2 or 3 aromatic rings of these aromatic groups are linked together. Specific examples of Ar include pyridine, pyrimidine, triazine, and the like, which are the same as those of Ar above except that they contain a nitrogen-containing 6-membered ring. １ ~Ar ３ This is the same as in the case of

[0038] Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl. These may be deuterated. Deuterated alkyl groups having 1 to 4 carbon atoms are preferred. Propyl and pentyl groups may be linearly linked or branched, and hexyl and heptyl groups may be linearly or cyclically linked or branched. These may be deuterated. Deuterated linear or branched propyl groups are preferred.

[0039] a to d represent the number of substitutions, a and d each independently represent an integer of 1 to 4, and b and c each represent an integer of 1 to 2. １ ~R ４When R does not contain hydrogen or deuterium, preferably a and d are integers of 1 to 2, b and c are integers of 1, and more preferably a, b, c, and d are integers of 1. When R contains hydrogen or deuterium, preferably a and d are integers of 3 to 4, b and c are integers of 2, a and d are integers of 4, and b and c are integers of 2. The sum of a to d may be 1 or more, and preferably 4 or more. １ ~R ４ It is preferred that at least one of the following is present as deuterium.

[0040] In the general formula (5), Ar ４ ~Ar ６ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 7 aromatic rings of these aromatic groups are linked together. Preferably, they are a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 3 aromatic hydrocarbon groups are linked together. More preferably, they are a substituted or unsubstituted phenyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted indolocarbazolyl group, a substituted or unsubstituted dibenzofuranyl group, or a substituted or unsubstituted linked aromatic group in which 2 to 3 aromatic rings of these aromatic groups are linked together. X 1 ~X 3 are each independently N or C—H, and at least one is N. Preferably, X 1 ~X 3 At least two of X are N, and more preferably, 1 ~X 33 All of the above are N.

[0041] The above Ar ４ ~Ar ６Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, the unsubstituted aromatic heterocyclic group having 3 to 18 carbon atoms, or the substituted or unsubstituted linked aromatic group in which 2 to 7 of these aromatic rings are linked include those having the same or similar properties as those described above for Ar except that they contain indolocarbazole, a nitrogen-containing 6-membered ring such as pyridine, pyrimidine, or triazine, and the number of links in the linked aromatic group is 2 to 7. １ ~Ar ３ This is the same as in the case of

[0042] Preferred embodiments of the compound represented by formula (5) include compounds represented by structures such as those of formulas (6) and (7).

[0043] In general formula (6), ring A is a substituted five-membered heterocycle represented by formula (6a), which is fused to two adjacent rings at any position, but is not fused to a side containing N. Therefore, the indolocarbazole ring has several isomeric structures, but the number is limited. Depending on the isomeric structure of the indolocarbazole ring, the compound represented by general formula (6) is specifically represented by structures such as those of formulas (8) to (11), preferably formulas (8), (10), and (11), and more preferably formula (10) or formula (11).

[0044]

[0045] The compound represented by general formula (7) is specifically represented by a structure such as those of the above formulas (12) to (15), preferably those of formulas (13), (14), and (15), and more preferably a structure represented by formula (15).

[0046] Ar in general formula (6) ７ ~Ar ９ Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, the unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or the linked aromatic group in which 2 to 5 of these aromatic rings are linked include those in which the number of linked aromatic groups is 2 to 5, and Ar ９ is the same as Ar in the above general formula (1), except that it includes pyridine, pyrimidine, and triazine. １ ~Ar ３The same applies to the case of Ar in the general formula (7). Preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 3 of the aromatic hydrocarbon groups are linked together. １０ ~Ar １２ is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group in which 2 or 3 of these aromatic rings are linked together, and is the same as Ar in the above general formula (1) except that it contains a nitrogen-containing 6-membered ring such as pyridine, pyrimidine, or triazine. １ ~Ar ３ Preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of the aromatic hydrocarbon groups are linked together.

[0047] R ８ ~R １０ and R １４ ~R １５ are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. Preferred are hydrogen, deuterium, or a substituted or unsubstituted phenyl group. More preferred are hydrogen and deuterium. Also, R ８ ~R １５ is an aromatic hydrocarbon group, R ８ ~R １５ may be condensed with the benzene ring or aromatic ring to which it is bonded to form a ring.

[0048] R ８ ~R １０ and R １４ ~R １５ Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms or the unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms include those having the same structure as Ar above except that they contain a nitrogen-containing 6-membered ring such as pyridine, pyrimidine, and triazine. ４ ~Ar ６ This is the same as in the case of

[0049] R ８ ~R１０ and R １４ ~R １５ Specific examples of when R is an aliphatic hydrocarbon group having 1 to 10 carbon atoms include １ ~R ４ is the same as those described in the specific examples when is an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0050] In this specification, the term "linked aromatic group" refers to an aromatic group in which the aromatic rings of two or more aromatic groups are linked by a single bond. These linking aromatic groups may be linear or branched. The linking position when the benzene rings are linked may be ortho, meta, or para, but para- or meta-linking is preferred. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and the multiple aromatic groups may be the same or different.

[0051] In this specification, the aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group may each have a substituent. When the substituent has a substituent, the substituent is preferably deuterium, halogen, cyano, triarylsilyl, aliphatic hydrocarbon group having 1 to 10 carbon atoms, alkenyl group having 2 to 5 carbon atoms, alkoxy group having 1 to 5 carbon atoms, or diarylamino group having 12 to 44 carbon atoms. When the substituent is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, it may be linear, branched, or cyclic. When the triarylsilyl group or diarylamino group serves as a substituent for the aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group, a single bond bonds silicon and carbon, or nitrogen and carbon, respectively. The number of the substituents is preferably 0 to 5, and more preferably 0 to 2. When the aromatic hydrocarbon group or aromatic heterocyclic group has a substituent, the number of carbon atoms in the substituent is not included in the calculation of the carbon number. However, it is preferable that the total carbon number, including the carbon atoms in the substituent, falls within the above range.

[0052] Specific examples of the substituent include deuterium, cyano, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, neopentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, vinyl, propenyl, butenyl, pentenyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, etc. Preferred are deuterium, cyano, methyl, ethyl, t-butyl, propyl, butyl, pentyl, neopentyl, hexyl, heptyl, or octyldiphenylamino, naphthylphenylamino, or dinaphthylamino.

[0053] f to h and m to n represent the number of substitutions, where f and h each independently represent an integer of 1 to 4, m and n each independently represent an integer of 1 to 3, and g each independently represent an integer of 1 or 2. R ８ ~R １０ and R １４ ~R １５ When R does not contain deuterium, preferably, f and h are integers of 1 or 2, and m and n are integers of 1 or 2, and more preferably, f to h and m to n are integers of 1. When R contains deuterium, preferably, f and h are integers of 2 or 4, m and n are integers of 2 or 3, and g is an integer of 1 or 2, and more preferably, f and h are integers of 4, m and n are integers of 3, and g is an integer of 2. Furthermore, the sum of f to h and m to n is preferably 1 or more, and more preferably 4 or more. ８ ~R １０ and R １４ ~R １５ It is preferred that at least one of the following is present as deuterium.

[0054] The compounds represented by general formulas (1) to (4) and general formula (5) may be deuterated to contain deuterium, or may not contain deuterium. In addition, both of the compounds represented by general formulas (1) to (4) and general formula (5) may contain deuterium, or may not contain deuterium. Furthermore, only one of the compounds may contain deuterium. When at least one of the compounds represented by general formulas (1) to (4) and general formula (5) is a compound containing deuterium, the performance (luminous efficiency and life) of the organic EL element is improved. Deuterium is a compound represented by R １ ~R ４ , and R ８ ~R １０ and R １４ ~R １５ By making at least a part of the group present as deuterium, it can be introduced into the compounds represented by general formulas (1) to (4) or general formula (5), or by making R １ ~R ４ , and R ８ ~R １０ and R １４ ~R １５ The compound may be one in which any of the above is used as a group such as an aliphatic hydrocarbon group and hydrogen contained in these groups is deuterated. Preferably, deuterium is introduced into the compound represented by general formula (1) to (4) or general formula (5).

[0055] Furthermore, some or all of the hydrogen atoms in the unsubstituted aromatic hydrocarbon group, unsubstituted aromatic heterocyclic group, unsubstituted linking aromatic group, substituents on these aromatic groups, or the aliphatic hydrocarbon group may be deuterated. That is, some or all of the hydrogen atoms in the compounds represented by general formulas (1) to (4) and the compound represented by general formula (5) may be deuterium atoms. Furthermore, the deuterated product includes both a single compound and a mixture of two or more compounds. Specifically, a deuteration ratio of 50% means that on average, half of all hydrogen atoms have been substituted with deuterium atoms. The deuterated product may be a single compound or a mixture of compounds with different deuteration ratios. In this specification, the deuteration ratio and the average deuteration ratio have the same meaning.

[0056] When part of the hydrogen atoms in the compounds represented by general formulas (1) to (4) and general formula (5) are deuterium, preferably 20% or more of all hydrogen atoms in the compounds represented by general formulas (1) to (4) and general formula (5) are deuterium, more preferably 40% or more, even more preferably 50% or more, and particularly preferably 80% or more.

[0057] The deuteration rate can be determined by mass spectrometry or proton nuclear magnetic resonance spectroscopy. For example, when determining by proton nuclear magnetic resonance spectroscopy, a measurement sample is first prepared by adding and dissolving the compound and an internal standard in a deuterated solvent, and the proton concentration [mol / g] of the compound contained in the measurement sample is calculated from the ratio of the integrated intensities derived from the internal standard and the compound. Next, the ratio of the proton concentration of the deuterated compound to the proton concentration of the corresponding non-deuterated compound is calculated, and the ratio is subtracted from 1 to calculate the deuteration rate of the deuterated compound. Furthermore, the deuteration rate of a partial structure can be calculated from the integrated intensities of the chemical shifts derived from the target partial structure using the same procedure as described above.

[0058] Specific examples of the compounds represented by the general formulas (1) to (4) are shown below, but the compounds are not limited to these exemplary compounds.

[0059]

[0060] Specific examples of the compound represented by the general formula (6) are shown below, but the present invention is not limited to these exemplary compounds.

[0061]

[0062]

[0063] Specific examples of the compound represented by the general formula (7) are shown below, but the compound is not limited to these exemplary compounds.

[0064]

[0065]

[0066]

[0067]

[0068]

[0069] The organic EL device of the present invention includes at least one emitting layer containing the first host represented by any one of general formulas (1) to (4) and the second host represented by general formula (5). The first host and the second host may be included in the emitting layer, or may be included in a mixed composition for forming the emitting layer. The mixed composition containing the first host and the second host may also contain a light-emitting dopant or other host material. The emitting layer can be formed by vaporizing and depositing two types of compounds from separate evaporation sources, or by mixing two types of compounds in advance to form a premixed composition, which is then vaporized and deposited from a single evaporation source. The latter method, also known as a premixed evaporation method, can provide an organic EL device with excellent performance and lifespan.

[0070] The proportion of the first host relative to the total of the first and second hosts is preferably 10 wt % or more and less than 80 wt %, and more preferably 20 wt % or more and less than 70 wt %. When the first host and the second host are contained in the mixed composition and the premixed composition, the proportion of the first host and the second host used is the same as above. Furthermore, it is desirable to maintain a constant evaporation rate of the two types of hosts during vapor deposition. To achieve this, it is advisable to keep the difference in evaporation temperature or 50% weight loss temperature between the two hosts within 20°C.

[0071] Next, the structure of the organic EL element of the present invention will be described with reference to the drawings, but the structure of the organic EL element of the present invention is not limited to this.

[0072] FIG. 1 is a cross-sectional view showing an example of the structure of a typical organic EL device, in which 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents an emitting layer, 6 represents an electron transport layer, and 7 represents a cathode. The organic EL device of the present invention may have an exciton blocking layer adjacent to the emitting layer, or an electron blocking layer between the emitting layer and the hole injection layer. The exciton blocking layer can be inserted on either the anode side or the cathode side of the emitting layer, or both simultaneously. The organic EL device of the present invention has an anode, an emitting layer, and a cathode as essential layers, but may also have a hole injection transport layer and an electron injection transport layer in addition to the essential layers, and may further have a hole blocking layer between the emitting layer and the electron injection transport layer. Note that the hole injection transport layer refers to either the hole injection layer or the hole transport layer, or both, and the electron injection transport layer refers to either the electron injection layer or the electron transport layer, or both.

[0073] It is also possible to have a structure opposite to that shown in FIG. 1 , that is, to stack the cathode 7, electron transport layer 6, light-emitting layer 5, hole transport layer 4, hole injection layer 3, and anode 2 on the substrate 1 in this order, and in this case too, layers can be added or omitted as necessary.

[0074] The organic EL device of the present invention is preferably supported on a substrate. There are no particular limitations on the substrate, and any substrate conventionally used in organic EL devices, such as glass, transparent plastic, or quartz, can be used.

[0075] Anode: Anode materials for organic EL devices are preferably metals, alloys, electrically conductive compounds, or mixtures thereof with a high work function (4 eV or greater). Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. Amorphous materials capable of forming transparent conductive films, such as IDIXO (In2O3-ZnO), may also be used. The anode may be formed by forming a thin film of these electrode materials by methods such as vapor deposition or sputtering, followed by photolithography to form a desired pattern. Alternatively, if pattern precision is not required (approximately 100 μm or greater), a pattern may be formed using a mask of the desired shape during vapor deposition or sputtering of the electrode material. Alternatively, when using a coatable material such as an organic conductive compound, wet film formation methods such as printing or coating can also be used. When light is emitted from this anode, a transmittance of more than 10% is desirable, and the sheet resistance of the anode is preferably less than several hundred Ω / □. The film thickness varies depending on the material, but is usually selected from the range of 10 to 1000 nm, preferably 10 to 200 nm.

[0076] - Cathode - On the other hand, as the cathode material, a metal (electron injecting metal), alloy, electrically conductive compound, or a material consisting of a mixture thereof, having a small work function (4 eV or less) is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ２ O ３) mixtures, indium, lithium / aluminum mixtures, rare earth metals, etc. Among these, from the viewpoints of electron injection ability and durability against oxidation, etc., mixtures of an electron injection metal and a second metal having a larger and more stable work function than the electron injection metal, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide mixtures, lithium / aluminum mixtures, and aluminum, are preferred. The cathode can be fabricated by forming a thin film of these cathode materials by methods such as vapor deposition or sputtering. Furthermore, the cathode preferably has a sheet resistance of several hundred Ω / □ or less, and the film thickness is typically selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. It is advantageous to make either the anode or cathode of the organic EL device transparent or semitransparent to allow the emitted light to pass through, thereby improving the luminance of the emitted light.

[0077] Furthermore, a transparent or semitransparent cathode can be fabricated by forming the above-mentioned metal as a cathode with a thickness of 1 to 20 nm and then forming the conductive transparent material mentioned in the description of the anode on top of it. This can be applied to fabricate an element in which both the anode and cathode are transparent.

[0078] -Light-emitting layer- The light-emitting layer is a layer that emits light after excitons are generated by recombination of holes and electrons injected from the anode and cathode, respectively, and preferably contains an organic light-emitting dopant material and a host material.

[0079] The host includes the first host and the second host. If necessary, one or more other host materials, such as known host materials, may be used in combination. The other host material is preferably a compound that has hole transporting ability and electron transporting ability, prevents the emission wavelength from shifting to a longer wavelength, and has a high glass transition temperature.

[0080] Other host materials are known from many patent documents and can be selected from them. Specific examples of the host material include, but are not limited to, indolocarbazole derivatives described in WO2008 / 056746A1, WO2008 / 146839A1, etc., carbazole derivatives described in WO2009 / 086028A1, WO2012 / 077520A1, etc., CBP (N,N-biscarbazolylbiphenyl) derivatives, triazine derivatives described in WO2014 / 185595A1, WO2018 / 021663A1, etc., indenocarbazole derivatives described in WO2010 / 136109A1, WO2011 / 000455A1, etc., and the like. Dibenzofuran derivatives, triazole derivatives, indole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidene compounds, porphyrin compounds, anthraquinodimethane compounds, and the like, as described in JP 2015 / 169412A1, etc. Examples of the compound include heterocyclic tetracarboxylic acid anhydrides such as phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, and metal complexes of benzoxazole and benzothiazole derivatives; polymer compounds such as polysilane compounds, poly(N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylenevinylene derivatives, and polyfluorene derivatives.

[0081] Specific examples of the other host materials are shown below, but are not limited to these.

[0082] When multiple types of hosts are used, each host can be vapor-deposited from a different vapor deposition source, or multiple types of hosts can be simultaneously vapor-deposited from one vapor deposition source by premixing them before vapor deposition to form a premixed composition.

[0083] The premixing method is preferably a method that allows mixing as uniformly as possible, and examples thereof include pulverization and mixing, heating and melting under reduced pressure or in an inert gas atmosphere such as nitrogen, and sublimation, but are not limited to these methods.

[0084] The premix composition may be in the form of a powder, stick, or granules.

[0085] The organic light-emitting dopant material is preferably a phosphorescent dopant, a fluorescent dopant, or a thermally activated delayed fluorescent dopant.

[0086] The phosphorescent dopant may be an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Specifically, the iridium complexes described in J.Am.Chem.Soc.2001,123,4304, JP2013-530515A, US2016 / 0049599A1, US2017 / 0069848A1, US2018 / 0282356A1, or US2019 / 0036043A1, or the platinum complexes described in US2018 / 0013078A1 or KR2018 / 094482A are preferably used, but are not limited to these.

[0087] The phosphorescent dopant material may be contained in the light-emitting layer alone or in combination with two or more other materials. The content of the phosphorescent dopant material is preferably 0.1 to 30 wt %, more preferably 1 to 20 wt %, based on the host material.

[0088] The phosphorescent dopant material is not particularly limited, but specific examples include the following.

[0089]

[0090] The fluorescent dopant is not particularly limited, but examples thereof include benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds, perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyrrolidine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, styrylamine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidine compounds, various metal complexes typified by metal complexes of 8-quinolinol derivatives, metal complexes of pyrromethene derivatives, rare earth complexes, and transition metal complexes; polymer compounds such as polythiophene, polyphenylene, and polyphenylenevinylene; and organic silane derivatives. Preferred examples include fused aromatic derivatives, styryl derivatives, diketopyrrolopyrrole derivatives, oxazine derivatives, pyrromethene metal complexes, transition metal complexes, and lanthanoid complexes, and more preferred examples include naphthalene, pyrene, chrysene, triphenylene, benzo[c]phenanthrene, benzo[a]anthracene, pentacene, perylene, fluoranthene, acenaphthofluoranthene, dibenzo[a,j]anthracene, dibenzo[a,h]anthracene, benzo[a]naphthalene, hexacene, naphtho[2,1-f]isoquinoline, α-naphthaphenanthridine, phenanthroxazole, quinolino[6,5-f]quinoline, and benzothiophanthrene. These may have an alkyl group, an aryl group, an aromatic heterocyclic group, or a diarylamino group as a substituent.

[0091] The light-emitting layer may contain one or more fluorescent dopant materials, and the content of the fluorescent dopant material is preferably 0.1 to 20 wt %, more preferably 1 to 10 wt %, relative to the host material.

[0092] The thermally activated delayed fluorescent dopant is not particularly limited, but examples thereof include metal complexes such as tin complexes and copper complexes, indolocarbazole derivatives described in WO2011 / 070963A1, cyanobenzene derivatives and carbazole derivatives described in Nature 2012,492,234, phenazine derivatives, oxadiazole derivatives, triazole derivatives, sulfone derivatives, phenoxazine derivatives and acridine derivatives described in Nature Photonics 2014,8,326, and the like.

[0093] The thermally activated delayed fluorescent dopant material is not particularly limited, but specific examples include the following.

[0094]

[0095] The light-emitting layer may contain only one type of thermally activated delayed fluorescent dopant material, or two or more types. The thermally activated delayed fluorescent dopant may be mixed with a phosphorescent dopant or a fluorescent dopant. The content of the thermally activated delayed fluorescent dopant material is preferably 0.1 to 50 wt %, more preferably 1 to 30 wt %, relative to the host material.

[0096] Injection layer: An injection layer is a layer provided between an electrode and an organic layer to reduce driving voltage and improve luminance, and includes a hole injection layer and an electron injection layer. An injection layer may be provided between the anode and the light-emitting layer or the hole transport layer, and between the cathode and the light-emitting layer or the electron transport layer. An injection layer can be provided as needed.

[0097] -Hole-blocking layer- In a broad sense, the hole-blocking layer functions as an electron-transporting layer, and is made of a hole-blocking material that has the function of transporting electrons but an extremely small ability to transport holes. By transporting electrons while blocking holes, the hole-blocking layer can improve the probability of recombination of electrons and holes in the light-emitting layer.

[0098] - Electron Blocking Layer - In a broad sense, the electron blocking layer functions as a hole transporting layer, and can increase the probability of recombination of electrons and holes in the light-emitting layer by blocking electrons while transporting holes.

[0099] As the material for the electron blocking layer, known electron blocking layer materials can be used, and the materials for the hole transport layer described below can also be used as needed. The thickness of the electron blocking layer is preferably 3 to 100 nm, more preferably 5 to 30 nm.

[0100] -Exciton blocking layer- An exciton blocking layer is a layer that prevents excitons generated by the recombination of holes and electrons in the light-emitting layer from diffusing into the charge transport layer. Insertion of this layer makes it possible to efficiently confine excitons within the light-emitting layer, thereby improving the luminous efficiency of the device. In a device having two or more adjacent light-emitting layers, an exciton blocking layer can be inserted between two adjacent light-emitting layers.

[0101] The exciton blocking layer may be made of known materials, such as 1,3-dicarbazolylbenzene (mCP) and bis(2-methyl-8-quinolinolato)-4-phenylphenolatoaluminum(III) (BAlq).

[0102] -Hole Transport Layer- The hole transport layer is made of a hole transport material having a function of transporting holes, and the hole transport layer may be provided as a single layer or as a plurality of layers.

[0103] The hole transport material has either hole injection or transport properties or electron barrier properties, and may be either organic or inorganic. Any conventionally known compound can be selected and used for the hole transport layer. Examples of such hole transport materials include porphyrin derivatives, arylamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, particularly thiophene oligomers. Porphyrin derivatives, arylamine derivatives, and styrylamine derivatives are preferred, and arylamine derivatives are more preferred.

[0104] - Electron Transport Layer - The electron transport layer is made of a material having a function of transporting electrons, and the electron transport layer may be a single layer or multiple layers.

[0105] The electron transport material (which may also serve as a hole blocking material) may have the function of transporting electrons injected from the cathode to the light-emitting layer. The electron transport layer may be formed from any of conventionally known compounds, including, for example, polycyclic aromatic derivatives such as naphthalene, anthracene, and phenanthroline, tris(8-quinolinolato)aluminum(III) derivatives, phosphine oxide derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane derivatives, anthrone derivatives, bipyridine derivatives, quinoline derivatives, oxadiazole derivatives, benzimidazole derivatives, benzothiazole derivatives, and indolocarbazole derivatives. Furthermore, polymeric materials in which any of these materials are incorporated into a polymer chain or in which any of these materials form the main chain of a polymer may also be used.

[0106] The method for producing an organic electroluminescent device of the present invention includes a step of mixing a compound represented by one of general formulas (1) to (4) (a first host) with a compound represented by general formulas (6) and (7) (a second host) to prepare a premixed composition, and then evaporating the premixed composition from a single evaporation source to form an emitting layer by vapor deposition. Premixing the two host materials in this manner can improve the performance of the organic EL device. Powder mixing or melt mixing can be used as the mixing method.

[0107] In the premixed composition obtained by the above premixing, the difference between the 50% weight loss temperatures of the first host material and the second host material is preferably within 20° C. Here, the 50% weight loss temperature refers to the temperature at which the weight is reduced by 50% when the temperature is raised from room temperature to 550° C. at a rate of 10° C. per minute in TG-DTA measurement under reduced pressure (1 Pa) of nitrogen gas flow. It is believed that vaporization by evaporation or sublimation occurs most actively around this temperature.

[0108] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples and can be implemented in various forms as long as they do not depart from the gist of the invention.

[0109] As representative examples, the synthesis of compounds 1-4, 1-9, 1-426, 1-413, 1-427, and 1-477 is shown. Other compounds were synthesized in a similar manner. The deuteration ratio was determined by proton nuclear magnetic resonance spectroscopy.

[0110] Synthesis Example 1 To 10.0 g of compound (a), 23.7 g of compound (b), 20.2 g of sodium carbonate, 1.4 g of tetrakistriphenylphosphine palladium, 240 mL of m-xylene, 120 mL of ethanol, and 50 mL of water were added and stirred at 90°C for 69 hours under a nitrogen atmosphere. After cooling to room temperature, 300 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 9.18 g of compound (c) as a yellow solid (yield 94%).

[0111] Synthesis Example 2 To 8.8 g of compound (c), 45.1 g of triphenylphosphine and 200 mL of o-dichlorobenzene were added, and the mixture was stirred at 150°C for 6 hours under a nitrogen atmosphere. After cooling to room temperature, the mixture was purified by silica gel column chromatography to obtain 6.11 g of compound (d) as a brown solid (yield 82%).

[0112] Synthesis Example 3 To 2.6 g of compound (d), 4.6 g of (e), 0.3 g of copper(I) iodide, 0.4 g of 8-hydroxyquinoline, 4.2 g of potassium carbonate, and 80 mL of 1,3-dimethyl-2-imidazolidinone were added and stirred at 150°C for 64 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification by silica gel column chromatography yielded 4.3 g of compound 1-9 as a white solid (88% yield). (APCI-TOFMS, m / z 651 [M+H]+)

[0113] Synthesis Example 4 To 3.5 g of compound (d), 7.3 g of (g), 0.4 g of copper(I) iodide, 0.6 g of 8-hydroxyquinoline, 5.6 g of potassium carbonate, and 100 mL of 1,3-dimethyl-2-imidazolidinone were added and stirred at 150°C for 62 hours under a nitrogen atmosphere. After cooling to room temperature, 300 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. 300 mL of acetonitrile was added to the resulting solid and stirred at room temperature for 1 hour, yielding 4.8 g of compound 1-4 as a white solid (73% yield). (APCI-TOFMS, m / z 651 [M+H]+)

[0114] Synthesis Example 5 100 g of deuterated benzene was added to 10.0 g of compound 1-9 and stirred at 50°C under a nitrogen atmosphere for 0.5 hours. 11.5 g of trifluoromethanesulfonic acid was then added, followed by stirring at 50°C for an additional 3 hours under a nitrogen atmosphere. 8.8 g of sodium carbonate was added to 200 g of deuterium oxide and stirred at 0°C for 0.5 hours. The reaction mixture was then added and stirred for an additional 1 hour. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. 300 mL of ethanol was added to the resulting solid and stirred at room temperature for 1 hour, yielding 2.0 g of compound 1-413 as a white solid (yield 20%, deuteration rate 95%). (APCI-TOFMS, m / z 681 [M+H]+)

[0115] The average deuteration ratio of compound (1-413) was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving 5.0 mg of compound (1-413) and 2.0 mg of dimethyl sulfone as an internal standard in 1.0 ml of deuterated tetrahydrofuran. The average proton concentration [mol / g] of compound (1-413) contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and compound (1-413). The average proton concentration [mol / g] of the non-deuterated form of compound (1-413) (compound (1-9)) was also calculated in the same manner. Next, the ratio of the proton concentration of compound (1-413) to the proton concentration of compound (1-9) was calculated and subtracted from 1 to calculate the average deuteration ratio of compound (1-413) as 95%.

[0116] Synthesis Example 6 To 5.0 g of compound (h), 11.9 g of compound (b), 10.1 g of sodium carbonate, 0.7 g of tetrakistriphenylphosphine palladium, 120 mL of m-xylene, 60 mL of ethanol, and 25 mL of water were added and stirred at 90°C for 41 hours under a nitrogen atmosphere. After cooling to room temperature, 150 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 4.3 g of compound (i) as a yellow solid (yield 88%).

[0117] Synthesis Example 7 To 2.2 g of compound (j), 11.3 g of triphenylphosphine and 50 mL of o-dichlorobenzene were added, and the mixture was stirred for 6 hours at 150°C under a nitrogen atmosphere. After cooling to room temperature, the mixture was purified by silica gel column chromatography to obtain 1.4 g of compound (k) as a brown solid (yield 74%).

[0118] Synthesis Example 8 To 1.2 g of compound (k), 3.7 g of (g), 0.2 g of copper(I) iodide, 0.3 g of 8-hydroxyquinoline, 2.8 g of potassium carbonate, and 50 mL of 1,3-dimethyl-2-imidazolidinone were added and stirred at 150°C for 71 hours under a nitrogen atmosphere. After cooling to room temperature, 150 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. 150 mL of acetonitrile was added to the resulting solid and stirred at room temperature for 1 hour, yielding 2.2 g of compound 1-426 as a white solid (98% yield). (APCI-TOFMS, m / z 651 [M+H]+)

[0119] Synthesis Example 9 To 8.9 g of compound (L), 220 g of iodobenzene, 7.4 g of copper powder, and 27.4 g of potassium carbonate were added, and the mixture was stirred overnight at 10°C and 150°C under a nitrogen atmosphere. After cooling to room temperature, 500 mL of m-xylene and 500 mL of water were added. The aqueous and organic phases were separated, the aqueous layer was extracted with dichloromethane, and the organic layer was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography, yielding 8.3 g of compound (1-427) as a white solid (yield 80%). (APCI-TOFMS, m / z 574 [M+H]+)

[0120] Synthesis Example 10 To 10 g of compound (N), 187 g of deuterated bromobenzene, 8.0 g of copper powder, and 29.3 g of potassium carbonate were added, and the mixture was stirred overnight at 10°C and 150°C under a nitrogen atmosphere. After cooling to room temperature, 500 mL of m-xylene and 500 mL of water were added. The aqueous and organic phases were separated, the aqueous layer was extracted with dichloromethane, and the organic layer was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography, yielding 15.4 g of compound (1-477) as a white solid (75% yield, 92% deuteration rate). (APCI-TOFMS, m / z 601 [M+H]+)

[0121] The average deuteration ratio of compound (1-477) was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving 5.0 mg of compound (1-477) and 2.0 mg of dimethyl sulfone as an internal standard in 1.0 ml of deuterated tetrahydrofuran. The average proton concentration [mol / g] of compound (1-477) contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and compound (1-477). The average proton concentration [mol / g] of the non-deuterated form of compound (1-477) (compound (1-427)) was also calculated in the same manner. Next, the ratio of the proton concentration of compound (1-477) to the proton concentration of compound (1-427) was calculated and subtracted from 1 to calculate the average deuteration ratio of compound (1-477) as 92%.

[0122] The compounds used in the examples and comparative examples are shown below.

[0123] Reactions were carried out in the same manner as in Synthesis Examples 1 to 4 and 7 to 8 to synthesize Example Compounds 1-2, 1-3, 1-91, 1-94, 1-448, 1-449, 1-460, and 1-461, and Comparative Compounds A and B. Reactions were also carried out in the same manner as in Synthesis Examples 5 and 9 to synthesize Example Compounds 1-480, 1-483, 1-501, 1-504, 1-507, 1-509, 2-512, 2-541, 2-545, and 3-70, which are deuterated compounds, and Comparative Compound C.

[0124] The deuteration rates of Example Compounds 1-480, 1-483, 1-501, 1-504, 1-507, 1-509, 2-512, 2-519, 2-541, 2-545, and 3-70, and Comparative Example Compound C are also shown in Table 1.

[0125] Example 1 Each thin film was deposited by vacuum deposition on a glass substrate on which an anode made of ITO with a film thickness of 110 nm was formed at a vacuum degree of 4.0 × 10 -5The layers were laminated at 1000 W / m². First, HAT-CN was formed as a hole-injection layer to a thickness of 25 nm on ITO, followed by Spiro-TPD as a hole-transport layer to a thickness of 30 nm. Next, HT-1 was formed as an electron-blocking layer to a thickness of 10 nm. Next, Compound 1-4 was co-deposited as the first host, Compound 2-465 as the second host, and Ir(ppy)3 as the emitting dopant from separate evaporation sources to form a 40 nm-thick emitting layer. The co-deposition conditions were a 10 wt% Ir(ppy)3 concentration and a 70:30 weight ratio of the first host to the second host. Next, ET-1 was formed as an electron-transport layer to a thickness of 20 nm. Furthermore, LiF was formed as an electron-injection layer to a thickness of 1 nm on the electron-transport layer. Finally, Al was formed as a cathode to a thickness of 70 nm on the electron-injection layer to fabricate an organic EL device.

[0126] Examples 2 to 38 and Comparative Examples 1 to 6 Organic EL devices were prepared in the same manner as in Example 1, except that the compounds shown in Tables 2-1 and 2-2 were used as the first host and the second host in the weight ratios shown in Tables 2-1 and 2-2.

[0127] Examples 39 to 48 and Comparative Examples 7 and 8 Organic EL devices were prepared in the same manner as in Example 1, except that the first host and the second host shown in Table 2-2 were weighed out so as to have the weight ratio shown in Table 2-2, and mixed while grinding in a mortar to obtain a premixed composition, and then vapor-deposited from a single vapor deposition source.

[0128] The evaluation results of the fabricated organic EL devices are shown in Tables 2-1 and 2-2. In the tables, the luminance, voltage, and power efficiency are measured at a driving current of 10 mA / cm. 2 The values ​​are those at the time of the drive current of 20mA / cm², which are the initial characteristics. 2 The time it takes for the luminance to decay to 97%, assuming the initial luminance at 100%, represents the lifespan characteristics. The numbers in the columns for first host and second host in the table correspond to the numbers assigned to the exemplified compounds, and the weight ratio is first host:second host.

[0129]

[0130] The results in Tables 2-1 and 2-2 show that, for example, Examples 1 and 2 and Examples 10 to 15 have improved luminance, efficiency, and lifetime compared to Comparative Example 2. Furthermore, Examples 3, 6, 18 to 23, 26, and Examples 37 to 44 have improved luminance, efficiency, and lifetime compared to Comparative Example 3. It can be seen that Example 45 has improved luminance, efficiency, and lifetime compared to Comparative Example 7, and Example 46 has improved luminance, efficiency, and lifetime compared to Comparative Example 8, demonstrating favorable characteristics. In addition, when the other Examples are compared among those having the same weight ratio of the first host to the second host, it can be seen that they have improved efficiency and lifetime compared to Comparative Examples 1 to 6 and Comparative Examples 7 to 8, demonstrating favorable characteristics.

[0131] Table 3 shows the 50% weight loss temperatures (T 50 ) is written.

[0132]

[0133] According to the present invention, by using a predetermined material for an organic electroluminescent device, it is possible to realize a practically useful organic EL device which operates at a low voltage, has high efficiency, and has long life characteristics.

[0134] 1 Substrate, 2 Anode, 3 Hole injection layer, 4 Hole transport layer, 5 Light-emitting layer, 6 Electron transport layer, 7 Cathode

Claims

1. A material for organic electroluminescent devices represented by any one of the following general formulas (1) to (4): (In the general formulas (1) to (4), Ar １ and Ar ２ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic groups are linked together. １ and Ar ２ When R is an aromatic heterocyclic group, it is an aromatic group that does not contain a nitrogen-containing six-membered ring. １ ~R 4 are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic groups are linked together. １ ~R 4 When X is an aromatic hydrocarbon group, it may be condensed with the benzene ring to which it is attached to form a ring. ３ and Ar is selected from ３ is a substituted or unsubstituted aromatic heterocyclic group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group in which 2 to 3 aromatic rings of these aromatic groups are linked together. ３ When is an aromatic heterocyclic group, it is an aromatic group that does not contain a nitrogen-containing six-membered ring. a to d are the number of substitutions, a and d are integers of 1 to 4, and b and c are integers of 1 to 2.

2. The above R １ ~R 4 is hydrogen, deuterium, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two such aromatic groups are linked together.

3. The material for organic electroluminescent devices according to claim 1, wherein X is O or S.

4. The Ar １ and Ar ２ 2. The material for organic electroluminescent devices according to claim 1, wherein at least one of the above is a substituted or unsubstituted benzene, carbazole, dibenzofuran, or a substituted or unsubstituted linking aromatic group in which 2 to 3 of these are linked together.

5. An organic electroluminescent device comprising one or more organic layers between opposing anode and cathode, wherein at least one of the organic layers contains a material for organic electroluminescent devices represented by any one of general formulas (1) to (4) described in claim 1.

6. An organic electroluminescent device comprising one or more emitting layers between an anode and a cathode facing each other, characterized in that at least one emitting layer contains a first host selected from the compounds represented by general formulas (1) to (4) set forth in claim 1, a second host selected from the compounds represented by the following general formula (5), and a luminescent dopant material: (In the general formula (5), Ar 4 , Ar ５ , and Ar ６ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 7 of these aromatic rings are linked together. 1 ~X 3 are each independently N or C—H, and at least one is N.

7. The organic electroluminescent device according to claim 6, wherein the general formula (5) is represented by the following formula (6): In the general formula (6), ring A is a heterocycle represented by formula (6a) which is fused with two adjacent rings at any position. ７ , Ar ８ , and Ar ９ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together. L is a direct bond, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. R ８ ~R １０ are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. f to h are the number of substitutions, and f and h are integers of 1 to 4, and g is an integer of 1 or 2. X 1 ~X 3 has the same meaning as in the general formula (5).

8. The organic electroluminescent device according to claim 6, wherein the general formula (5) is represented by the following formula (7): (In the general formula (7), Ar １０ , Ar １１ , and Ar １２ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 or 3 of these aromatic rings are linked together. １４ ~R １５ are each independently hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. Y is selected from O and S, and m and n are the number of substitutions and are integers of 1 to 3. X 1 ~X 3 has the same meaning as in the general formula (5).

9. The organic electroluminescent device according to claim 7, wherein the general formula (6) is represented by any one of the following formulas (8) to (11): (where Ar ７ , Ar ８ , Ar ９ , R ８ , R ９ , R １０ , f, g, and h have the same meanings as in the general formula (6).

10. The organic electroluminescent device according to claim 8, wherein the general formula (7) is represented by any one of the following formulas (12) to (15): (where Ar １０ , Ar １１ , Ar １２ , R １４ , R １５ , m, and n are the same as those in the general formula (7).

11. The organic electroluminescent device according to claim 9, wherein the general formula (6) is represented by the general formula (10) or (11).

12. The organic electroluminescent device according to claim 10, wherein the general formula (7) is represented by the general formula (15).

13. The Ar ９ is a substituted or unsubstituted benzene, pyridine, pyrimidine, triazine, carbazole, dibenzofuran, triphenylene, or a substituted or unsubstituted linking aromatic group in which 2 to 3 of these are linked together.

14. The Ar １０ is a substituted or unsubstituted benzene, pyridine, pyrimidine, triazine, carbazole, dibenzofuran, triphenylene, or a substituted or unsubstituted linking aromatic group in which 2 to 3 of these are linked together.

15. The organic electroluminescent device according to claim 6, wherein the luminescent dopant material is an organometallic complex containing at least one metal selected from the group consisting of ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold.

16. The organic electroluminescent device according to claim 6, wherein the luminescent dopant material is a thermally activated delayed fluorescent dopant material.

17. A mixed composition comprising a compound represented by any one of general formulas (1) to (4) described in claim 1 as a first host, and a compound represented by general formula (6) described in claim 7 or general formula (7) described in claim 8 as a second host.

18. The mixed composition according to claim 17, characterized in that it contains a compound represented by any one of general formulas (1) to (4) according to claim 1 as a first host, and a compound represented by general formula (11) according to claim 9 or general formula (15) according to claim 10 as a second host.

19. The mixed composition according to claim 17, wherein the difference between the 50% weight loss temperatures of the first host and the second host is within 20°C.

20. A method for producing an organic electroluminescent device, comprising the steps of: mixing, in advance, a compound represented by any one of general formulas (1) to (4) set forth in claim 1 as a first host; and a compound represented by any one of general formulas (6) set forth in claim 7 or general formula (7) set forth in claim 8 as a second host to prepare a premixed composition; and depositing a host material containing the premixed composition to form a light-emitting layer.

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