Organic electroluminescent element

Abstract

Provided are a practically useful material and pre-mix composition for an organic electroluminescent element having low voltage, high efficiency and long lifetime characteristics, and an organic electroluminescent element comprising the same.　A material for this organic electroluminescent element is represented by any one of general formulae (1)-(7). In the formulae, Y is O or the like, Ar7 to Ar9 are each independently a substituted or unsubstituted C3-17 aromatic heterocyclic group or the like, at least one of which is represented by formula (1a). Ar1 and Ar2 are each independently a substituted or unsubstituted C6-18 aromatic hydrocarbon group or the like, and * represents the binding position with general formulae (1)-(7). R1 to R4 are each independently a hydrogen, deuterium or the like, X1 to X3 are each independently N or the like, and R is deuterium or the like. a to d each represent the number of substitutions, a and c are each an integer of 1-4, and b and d are each an integer of 1-2.

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 (7).

[0014] In the general formulas (1) to (7), Y is O, S, N—Ar. ９ and Ar is selected from 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 7 of these aromatic groups are linked together, and Ar ７ ~Ar ９ At least one of Ar represents the formula (1a). 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, and * represents the bonding position with the general formulae (1) to (7). 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. １ ~X ３are each independently N, C—H, or C—R, and at least one is N. R is deuterium, 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. a to d are the number of substitutions, a and c are integers of 1 to 4, and b and d are integers of 1 or 2.

[0015] In the general formulas (1) to (7), 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; Y is O or S; Ar １ and Ar ２ or at least one of the above is either a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two of these aromatic rings are linked together, and it is a preferred embodiment of the present invention that any of the above is satisfied.

[0016] The present invention also relates to 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 an organic electroluminescent device represented by any one of the general formulas (1) to (7). Furthermore, the organic electroluminescent device also 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 any one of the general formulas (1) to (7), a second host selected from the compounds represented by the following general formula (8), 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 (7) have excellent electron injection and transport capabilities and can therefore be used as first hosts (also referred to as electron-transporting hosts or N-type hosts).

[0017] In the general formula (8), Ar ５ , and Ar ６are each independently hydrogen, deuterium, 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 groups are linked together. L are each independently a single bond, 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, R ５ ~R ６ are each independently hydrogen, deuterium, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms; g to j represent the number of substitutions; g and h are integers of 1 to 4; and i and j are integers of 1 to 3.

[0018] The compound of the general formula (8) may be represented by the following formula (9): In formula (9), the symbols common to general formula (8) have the same meanings.

[0019] In the general formula (8) or (9), g to j are g+h+i+j=14; R ５ , and R ６ At least one of the following is deuterium, or Ar ５ and Ar ６ is a substituted or unsubstituted phenyl group, biphenyl group, or terphenyl group, and satisfying any one of the above is a preferred embodiment of the present invention.

[0020] The luminescent dopant material is preferably an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold, or a thermally activated delayed fluorescent dopant material.

[0021] The present invention also provides a mixed composition comprising a compound represented by any one of the general formulas (1) to (7) as a first host and a compound represented by any one of the general formulas (8) or (9) as a second host. Among these, a mixed composition comprising a compound represented by any one of the general formulas (1) to (7) as a first host and a compound represented by the general formula (9) as a second host is preferred. The mixed composition may be in the form of a powder, solid, or thin film, as long as it contains a compound represented by any one of the general formulas (1) to (7) as a first host and a compound represented by any one of the general formulas (8) or (9) as a second host. The mixed composition may be prepared by mixing host compounds comprising a compound represented by any one of the general formulas (1) to (7) as a first host and a compound represented by any one of the general formulas (8) or (9) as a second host in powder form, 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 material may be formed as a vapor-deposited film by vapor deposition or the like. The vapor-deposited film may be formed by simultaneous vaporization from a single evaporation source, or by vaporization from separate evaporation sources. The vapor-deposited film includes a light-emitting layer having a dopant (light-emitting dopant material).

[0022] The mixing ratio of the mixed composition is preferably 10 wt % or more and less than 80 wt %, more preferably 20 wt % or more and less than 70 wt %, relative to the total of the compounds represented by the general formulas (1) to (7) and the compounds represented by the general formula (8) or the general formula (9), regardless of whether the mixed composition is in a powder state, whether the compounds are vaporized from separate vapor deposition sources, or whether the mixed composition is in a thin film state.

[0023] The present invention also provides a method for producing the organic electroluminescent device, comprising the steps of: premixing a compound represented by any one of general formulas (1) to (7) as a first host with a powder of a compound represented by general formula (8) or (9) as a second host to form a premixed composition; and then depositing a host material containing the premixed composition to form an emissive layer. In this specification, the premixed composition refers to a mixture of the compound represented by any one of general formulas (1) to (7) as a first host and a powder of a compound represented by general formula (8) or (9) as a second host.

[0024] In the above mixed composition and premixed composition, the difference in 50% weight loss temperature between the first host and the second host is preferably within 20°C.

[0025] According to the present invention, by using a predetermined material for organic electroluminescence devices, 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 biscarbazole 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.

[0026] FIG. 1 is a schematic cross-sectional view showing an example of an organic EL element.

[0027] The material for organic electroluminescent elements of the present invention comprises a compound represented by any one of the general formulas (1) to (7). The compounds represented by the general formulas (1) to (7) 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 (7) (first host), a compound represented by the general formula (8) or (9) (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. In the present application, the first host mainly performs electron injection and transport, and the second host mainly performs hole injection and transport. Here, the compound represented by any one of the general formulas (1) to (7) has excellent electron injection and transport ability and is useful as the electron injection and transport host material (also referred to as an N-type host material) for the material for organic electroluminescent elements. Hereinafter, the compounds represented by the general formulas (1) to (7) are also referred to as first hosts, and the compounds represented by the general formula (8) or (9) are also referred to as second hosts.

[0028] In the general formulae (1) to (7), the common symbols have the same meaning, and X in the general formulae (1) to (6) is preferable, and X in the general formulae (1) to (2) is more preferable. １ ~X ３ are each independently N, C—H, or C—R, and at least one is N. Preferably, X １ ~X ３ More preferably, two or more of X are N. １ ~X ３ All of the above are N. Each Y is independently O, S, or N-Ar. ９ and is preferably O or S, and more preferably O.

[0029] Ar ７ ~Ar ９are 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 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. 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 At least one of the above is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which two of these aromatic rings are linked together.

[0030] The above Ar ７ ~Ar ９Specific 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 7 of these aromatic rings are linked together include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, and isoxazole. , quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or a compound formed by linking 2 to 7 of these. Preferred are groups formed by removing hydrogen from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, carbazole, dibenzofuran, dibenzothiophene, or a compound formed by linking 2 to 5 of these. More preferred are groups formed from benzene, biphenyl, or terphenyl. The terphenyl group may be linearly linked or branched.

[0031] Ar １ , and Ar ２ 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 or 3 of these aromatic rings are linked include the same as those of the above Ar except that the number of links in the linked aromatic group is 2 or 3. ７ ~Ar ９ This is the same as the case described above.

[0032] 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. Preferred are 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 of these aromatic groups are linked together. More preferred are hydrogen, deuterium, and a phenyl group. 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.

[0033] Each R is independently deuterium, 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. Preferred are 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 of these aromatic groups are linked together. More preferred are hydrogen, deuterium, and a phenyl group. Furthermore, when R is an aromatic hydrocarbon group, it may be fused with the benzene ring or aromatic ring to which R is bonded to form a ring.

[0034] R １ ~R ４ Specific examples of when R 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 are the same as those of Ar above except that 2 or 3 aromatic rings of the aromatic hydrocarbon group or aromatic heterocyclic group are linked together. ７ ~Ar ９ This is similar to the specific example given above.

[0035] R １ ~R ４Specific examples of when is an 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. Preferably, it is a deuterated alkyl group having 1 to 4 carbon atoms. Propyl groups and pentyl groups may be linked in a linear or branched chain, and hexyl groups and heptyl groups may be linked in a linear or cyclic chain, or branched. These may also be deuterated. Preferably, it is a deuterated linear or branched propyl group.

[0036] a to d represent the number of substitutions, a and c each independently represent an integer of 1 to 4, and b and d each independently represent an integer of 1 to 2. １ ~R ４ When R does not contain hydrogen or deuterium, preferably a and c are integers of 1 or 2, and b and d 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 c are integers of 3 or 4, and b and d are integers of 2, and more preferably a and c are integers of 4, and b and d 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.

[0037] In the general formula (8), the two carbazole rings can be bonded at the 2-, 3-, or 4-positions, respectively, but are preferably bonded at the 3-position as shown in the general formula (9). In the general formulas (8) and (9), the same symbols have the same meanings.

[0038] In the general formula (8) or the general formula (9), Ar ５ ~Ar ６are each independently hydrogen, deuterium, 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 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 biphenyl group, or a substituted or unsubstituted terphenyl group.

[0039] Ar ５ ~Ar ６ 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 to 5 of these aromatic groups are linked, and specific examples thereof are the same as Ar except that the number of linked aromatic groups is 2 to 5. ７ ~Ar ９ This is the same as in the case of

[0040] In general formula (8) or general formula (9), each L is independently a single bond, 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. A single bond or a substituted or unsubstituted phenylene group is preferred. The linking mode may be ortho-, meta-, or para-linking.

[0041] A preferred embodiment of the compound represented by the general formula (8) is a compound represented by a structure such as the general formula (9).

[0042] R ５ and R ６ each independently represents hydrogen, deuterium, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. Deuterium is preferred. Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include R １ ~R ４ This is the same as in the case of

[0043] g to j and i to h represent the number of substitutions, where g and h represent integers of 1 to 4, and i and j represent integers of 1 to 3. R ５ ~R ６ When R does not contain hydrogen or deuterium, preferably, g and h are integers of 1 or 2, and i and j are integers of 1, and more preferably, g, h, i, and j are integers of 1. When R contains hydrogen or deuterium, preferably, g and h are integers of 3 or 4, and i and j are integers of 2 or 3, and more preferably, g and h are integers of 4, and i and j are integers of 3. The sum of g to j and i to h may be 1 or more, and preferably 4 or more. ５ ~R ６ It is preferred that at least one of the following is present as deuterium.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The compounds represented by the general formulas (1) to (7) and the compounds represented by the general formula (8) or (9) may be deuterated to contain deuterium, or may not contain deuterium. Furthermore, both the compounds represented by the general formulas (1) to (7) and the compounds represented by the general formula (8) or (9) may contain deuterium, or may not contain deuterium. Furthermore, only one of the compounds represented by the general formulas (1) to (7) or the compounds represented by the general formulas (8) or (9) may contain deuterium. When at least one of the compounds represented by the general formulas (1) to (7) and the compounds represented by the general formulas (8) or (9) is a compound containing deuterium, the performance (luminous efficiency and life) of the organic EL device is improved. Deuterium is a compound represented by R １ ~R ４ , and R ５ and R ６ By replacing at least a part of the group with deuterium, it can be introduced into the compounds represented by the general formulas (1) to (7) or the general formulas (8) and (9), or by introducing R １ ~R ４ , and R ５ and R ６The compound may be one in which hydrogen contained in any of the above groups is deuterated, using any of the above as the aliphatic hydrocarbon group, the aromatic hydrocarbon group, the aromatic heterocyclic group, or the linking aromatic group. Preferably, deuterium is introduced into a compound represented by any of general formulas (1) to (7), or a compound represented by general formula (8) or (9).

[0048] Furthermore, some or all of the hydrogen atoms in the unsubstituted aromatic hydrocarbon groups, unsubstituted aromatic heterocyclic groups, unsubstituted linking aromatic groups, substituents on these aromatic groups, and the aliphatic hydrocarbon groups specifically exemplified above may be deuterated. That is, some or all of the hydrogen atoms in the compounds represented by general formulas (1) to (7) and the compounds represented by general formulas (8) or (9) 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 terms "deuteration ratio" and "average deuteration ratio" have the same meaning.

[0049] When part of the hydrogen atoms in the compounds represented by general formulas (1) to (7), and general formula (8) or (9) are deuterium, preferably 20% or more of all hydrogen atoms in the compounds represented by general formulas (1) to (7), and general formula (8) or (9) are deuterium, more preferably 40% or more, even more preferably 50% or more, and most preferably 70% or more.

[0050] 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.

[0051] Specific examples of the compounds represented by the general formulas (1) to (7) are shown below, but the compounds are not limited to these exemplary compounds.

[0052]

[0053]

[0054] Specific examples of the compounds represented by the general formulas (8) and (9) are shown below, but the compounds are not limited to these exemplary compounds.

[0055]

[0056]

[0057]

[0058] The organic EL device of the present invention includes one or more emissive layers between opposing anode and cathode electrodes, wherein at least one of the emissive layers contains a first host represented by any one of the general formulas (1) to (7) and a second host represented by the general formula (8) or (9). The first host and second host may be contained in the emissive layer, or may be a mixed composition for forming the emissive layer. This mixed composition may contain a luminescent dopant or other host materials. The emissive layer can be formed by vaporizing two compounds from separate evaporation sources and depositing them, or by premixing two compounds to form a premixed composition, which is then vaporized from a single evaporation source and deposited. The latter method, also known as the premixed evaporation method, can produce organic EL devices with excellent performance and lifespan.

[0059] 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 and second hosts are contained in a mixed composition or a premixed composition, the proportions of the first and second hosts used are the same as above. In the case of a mixed composition or a premixed composition, it is desirable to maintain a constant evaporation rate of the two hosts. To this end, it is advisable to keep the difference in evaporation temperature or 50% weight loss temperature between the two hosts within 20°C.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] - 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.

[0066] 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.

[0067] -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.

[0068] 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.

[0069] 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.

[0070] Specific examples of the other host materials are shown below, but are not limited to these.

[0071] 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.

[0072] 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.

[0073] The premix composition may be in the form of a powder, stick, film or granules.

[0074] The organic light-emitting dopant material is preferably a phosphorescent dopant, a fluorescent dopant, or a thermally activated delayed fluorescent dopant.

[0075] 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.

[0076] 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.

[0077] The phosphorescent dopant material is not particularly limited, but specific examples include the following.

[0078]

[0079] 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 condensed aromatic derivatives, styryl derivatives, diketopyrrolopyrrole derivatives, oxazine derivatives, pyrromethene metal complexes, transition metal complexes, and lanthanoid complexes, and 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.

[0080] 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.

[0081] 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.

[0082] The thermally activated delayed fluorescent dopant material is not particularly limited, but specific examples include the following.

[0083]

[0084] 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.

[0085] 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.

[0086] -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.

[0087] - 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.

[0088] 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.

[0089] -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.

[0090] 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).

[0091] -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.

[0092] 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.

[0093] - 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.

[0094] 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.

[0095] 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 (7) (first host) with a compound represented by general formulas (8) and (9) (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.

[0096] 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.

[0097] 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.

[0098] As representative examples, the synthesis of compounds 1-3, 1-9, 1-89, 1-90, 1-131, and 2-117 is shown below. Other compounds were synthesized using similar methods. The deuteration ratio of the deuterated compounds was calculated by subtracting the ratio of the proton concentration of the corresponding deuterated compound obtained by proton nuclear magnetic resonance analysis from the proton concentration of the corresponding undeuterated compound.

[0099] Synthesis Example 1 0.11 g of 60 wt% sodium hydride was added to 30 ml of N,N'-dimethylacetamide (DMAc), and 1.0 g (2.37 mmol) of compound (a) dissolved in DMAc was added thereto and stirred for 30 minutes. 1.06 g (3.08 mmol) of compound (b) was then added thereto and stirred for 4 hours. The reaction product was separated and purified to obtain 0.69 g (0.95 mmol, 40% yield) of compound (1-3) as a yellow solid. (APCI-TOFMS, m / z 730 [M+H] + ).

[0100] Synthesis Example 2 0.11 g of 60 wt% sodium hydride was added to 30 ml of N,N'-dimethylacetamide (DMAc), and 1.0 g (2.37 mmol) of compound (c) dissolved in DMAc was added and stirred for 30 minutes. 1.06 g (3.08 mmol) of compound (b) was added to the mixture, and the mixture was stirred for 3 hours. The reaction product was separated and purified to obtain 0.65 g (0.89 mmol, 38% yield) of compound (1-9) as a yellow solid. (APCI-TOFMS, m / z 730 [M+H] + ).

[0101] Synthesis Example 3 To 0.5 g (0.69 mmol) of compound (1-3), 10 mL of deuterated benzene (CD6) and 3.0 g (20 mmol) of trifluoromethanesulfonic acid (TfOH) were added, and the mixture was heated and stirred at 50°C for 3 hours under a nitrogen atmosphere. The reaction mixture was added to a heavy water solution (20 mL) of sodium carbonate (2.3 g) and quenched. After separation and purification, 0.26 g (0.35 mmol, 50% yield, 89% deuteration) of the deuterated product, compound (1-89), was obtained. (APCI-TOFMS, m / z 761 [M+H] + ).

[0102] The average deuteration ratio of Compound 1-89 was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving Compound 1-89 (5.0 mg) and dimethyl sulfone (2.0 mg) as an internal standard in deuterated tetrahydrofuran (1.0 ml). The average proton concentration [mol / g] of Compound 1-89 contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and Compound 1-89. The average proton concentration [mol / g] of the non-deuterated form of Compound 1-89 (Compound 1-3) was also calculated in the same manner. Next, the ratio of the proton concentration of Compound 1-89 to the proton concentration of Compound 1-3 was calculated and subtracted from 1 to calculate the average deuteration ratio of Compound 1-89 as 89%.

[0103] Synthesis Example 4 To 0.5 g (0.69 mmol) of compound (1-9), 10 mL of deuterated benzene (CD6) and 3.0 g (20 mmol) of trifluoromethanesulfonic acid (TfOH) were added, and the mixture was heated and stirred at 50°C for 3 hours under a nitrogen atmosphere. The reaction mixture was added to a heavy water solution (20 mL) of sodium carbonate (2.3 g) and quenched. After separation and purification, 0.21 g (0.28 mmol, 40% yield, 87% deuteration) of the deuterated product, compound (1-90), was obtained. (APCI-TOFMS, m / z 761 [M+H] + ).

[0104] The average deuteration ratio of Compound 1-90 was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving Compound 1-90 (5.0 mg) and dimethyl sulfone (2.0 mg) as an internal standard in deuterated tetrahydrofuran (1.0 ml). The average proton concentration [mol / g] of Compound 1-90 contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and Compound 1-90. The average proton concentration [mol / g] of the non-deuterated form of Compound 1-90 (Compound 1-9) was also calculated in the same manner. Next, the ratio of the proton concentration of Compound 1-90 to the proton concentration of Compound 1-9 was calculated and subtracted from 1 to calculate the average deuteration ratio of Compound 1-90 as 87%.

[0105] Synthesis Example 5 To 8.3 g (14.8 mmol) of compound (2-2), 160 mL of deuterated benzene (CD6) and 10.0 g of deuterated trifluoromethanesulfonic acid (TfOD) were added, and the mixture was heated and stirred at 50°C for 6.5 hours under a nitrogen atmosphere. The reaction mixture was added to a deuterated solution (200 mL) of sodium carbonate (7.4 g) in water and quenched. After separation and purification, 2.0 g (3.40 mmol, 23% yield, 84% deuteration) of compound (2-117) was obtained as a white solid. (APCI-TOFMS, m / z 589 [M+H] + ).

[0106] The average deuteration ratio of compound 2-117 was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving compound 2-117 (5.0 mg) and dimethyl sulfone (2.0 mg) as an internal standard in deuterated tetrahydrofuran (1.0 ml). The average proton concentration [mol / g] of compound 2-117 contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and compound 2-117. The average proton concentration [mol / g] of the non-deuterated form of compound 2-117 (compound 2-2) was also calculated in the same manner. Next, the ratio of the proton concentration of compound 2-117 to the proton concentration of compound 2-2 was calculated and subtracted from 1 to calculate the average deuteration ratio of compound 2-117 as 84%.

[0107] Synthesis Example 6 0.11 g of 60 wt% sodium hydride was added to 30 ml of N,N'-dimethylacetamide (DMAc), and 1.2 g (2.37 mmol) of compound (d) dissolved in DMAc was added and stirred for 30 minutes. 0.86 g (3.08 mmol) of compound (e) was added, and the mixture was stirred for 3 hours. The reaction product was separated and purified to obtain 1.08 g (1.42 mmol, 60% yield, 90% deuteration) of compound (1-131) as a yellow solid. (APCI-TOFMS, m / z 762 [M+H] + ).

[0108] The average deuteration ratio of Compound 1-131 was determined by proton nuclear magnetic resonance spectroscopy. A measurement sample was prepared by dissolving Compound 1-131 (5.0 mg) and dimethyl sulfone (2.0 mg) as an internal standard in deuterated tetrahydrofuran (1.0 ml). The average proton concentration [mol / g] of Compound 1-131 contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and Compound 1-131. The average proton concentration [mol / g] of the non-deuterated form of Compound 1-131 (Compound 1-126) was also calculated in the same manner. Next, the ratio of the proton concentration of Compound 1-131 to the proton concentration of Compound 1-126 was calculated and subtracted from 1 to calculate the average deuteration ratio of Compound 1-131 as 90%.

[0109] The compounds used in the examples and comparative examples are shown below.

[0110] The remaining Example compounds and Comparative Example compounds were synthesized by carrying out reactions similar to those in Synthesis Examples 1 and 2. The remaining Example compounds and Comparative Example compounds, which are deuterated compounds, were synthesized by carrying out reactions similar to those in Synthesis Examples 3 to 6. The deuteration ratios were determined for Example Compounds 1-94, 1-95, 2-220, 2-233, and 2-235 by the same method as described above. The results are shown in Table 1.

[0111]

[0112] 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 70 nm was formed at a vacuum degree of 4.0 × 10 -5The layers were laminated using a Pa process. First, HAT-CN was formed to a thickness of 25 nm as a hole injection layer on ITO, and then Spiro-TPD was formed to a thickness of 30 nm as a hole transport layer. Next, HT-1 was formed to a thickness of 10 nm as an electron blocking layer. Next, Compound 1-3 was co-deposited from separate evaporation sources as a host and Ir(ppy)3 as an emitting dopant to form a 40 nm thick emitting layer. This was done under evaporation conditions that resulted in an Ir(ppy)3 concentration of 10 wt%. Next, ET-1 was formed to a thickness of 20 nm as an electron transport layer. Furthermore, LiF was formed to a thickness of 1 nm as an electron injection layer on the electron transport layer. Finally, Al was formed to a thickness of 70 nm as a cathode on the electron injection layer to fabricate an organic EL device.

[0113] Examples 2 to 11 and Comparative Examples 1 to 3 Organic EL devices were prepared in the same manner as in Example 1, except that the compounds shown in Table 2 were used as hosts.

[0114] The evaluation results of the fabricated organic EL devices are shown in Table 2. In the table, 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 of the host compounds are the same as those assigned to the above example compounds.

[0115]

[0116] Example 12 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 deposited to a thickness of 25 nm as a hole-injection layer on ITO, followed by Spiro-TPD to a thickness of 30 nm as a hole-transport layer. Next, HT-1 was deposited to a thickness of 5 nm as an electron-blocking layer. Next, Compound 1-3 was deposited as a first host, Compound 2-2 as a second host, and Ir(ppy)3 as an emitting dopant from separate deposition sources to form a 35 nm-thick emitting layer. The deposition conditions were a 10 wt% Ir(ppy)3 concentration and a 30:70 weight ratio of the first host to the second host. Next, ET-1 was deposited to a thickness of 20 nm as an electron-transport layer. LiF was then deposited to a thickness of 1 nm as an electron-injection layer on the electron-transport layer. Finally, Al was deposited to a thickness of 70 nm as a cathode on the electron-injection layer to fabricate an organic EL device.

[0117] Examples 13 to 42 and Comparative Examples 4 to 12 Organic EL devices were prepared in the same manner as in Example 12, except that the compounds shown in Tables 3-1 and 3-2 were used as the first host and the second host in the weight ratios shown in Tables 3-1 and 3-2.

[0118] Examples 43 to 46, Comparative Examples 13 and 14 Organic EL devices were prepared in the same manner as in Example 12, except that the first host and the second host shown in Tables 3-1 and 3-2 were weighed out so as to have the weight ratios shown in Tables 3-1 and 3-2, and mixed while grinding in a mortar to obtain premixed compositions, and then vapor-deposited the premixed compositions from a single vapor deposition source.

[0119] The evaluation results of the fabricated organic EL devices are shown in Tables 3-1 and 3-2. 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 of the host compound, first host, and second host are the numbers assigned to the above example compounds, and the weight ratio is first host:second host.

[0120]

[0121] From the results of Tables 3-1 and 3-2, it can be seen that Examples 12, 14, and 16 to 24 have improved efficiency and lifespan compared to Comparative Examples 4 to 6. In addition, Examples 34, 37, and 39 to 42 have improved efficiency and lifespan compared to Comparative Examples 7, 9 to 10, and Examples 43 to 46 also exhibit good characteristics compared to Comparative Examples 13 and 14, similar to the above examples, and the other Examples also exhibit good device characteristics compared to the Comparative Examples.

[0122] Table 4 shows the 50% weight loss temperature (T 50 ) is written.

[0123]

[0124] 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.

[0125] 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 (7): (In the general formulas (1) to (7), Y is O, S, N-Ar ９ and Ar is selected from 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 7 of these aromatic groups are linked together, and Ar ７ ~Ar ９ At least one of Ar represents the formula (1a). 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, and * represents the bonding position with the general formulae (1) to (7). 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. １ ~X ３ are each independently N, C-H, or C-R, and at least one is N. R is deuterium, 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. a to d are the number of substitutions, a and c are integers of 1 to 4, and b and d are integers of 1 or 2.

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

3. The above X １ ~X ３ 2. The material for an organic electroluminescent device according to claim 1, wherein all of the above are N.

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

5. The Ar １ , and Ar ２ 2. The material for organic electroluminescent elements according to claim 1, wherein at least one of the above is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linking aromatic group in which two of these aromatic rings are linked together.

6. An organic electroluminescent device comprising one or more organic layers between opposing anode and cathode, wherein at least one of the organic layers contains the material for organic electroluminescent devices according to claim 1.

7. An organic electroluminescent device comprising one or more emitting layers between opposing anode and cathode, wherein at least one emitting layer contains a first host material selected from the materials for organic electroluminescent devices described in any one of claims 1 to 5, a second host material selected from compounds represented by the following general formula (8), and a luminescent dopant material: (where Ar ５ , and Ar ６ each independently represents hydrogen, deuterium, 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 groups are linked together; each L independently represents a single bond, 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; R ５ ~R ６ each independently represents hydrogen, deuterium, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms; g to j represent the number of substitutions; g and h represent integers of 1 to 4; and i and j represent integers of 1 to 3.

8. The organic electroluminescent device according to claim 7, wherein the general formula (8) is represented by the following formula (9): (where Ar ５ , Ar ６ , L, R ５ , R ６ , g to j have the same meanings as in general formula (8).

9. The Ar ５ , and Ar ６ 8. The organic electroluminescent device according to claim 7, wherein each of the groups independently represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group.

10. The above R ５ , and R ６ 8. The organic electroluminescent device according to claim 7, wherein at least one of the above is deuterium.

11. The organic electroluminescent device according to claim 10, wherein g to j satisfy g+h+i+j=14.

12. The organic electroluminescent device according to claim 7, 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.

13. The organic electroluminescent device according to claim 7, wherein the luminescent dopant material is a thermally activated delayed fluorescent dopant material.

14. A mixed composition comprising a compound represented by any one of general formulas (1) to (7) according to claim 1 as a first host, and a compound represented by general formula (8) according to claim 6 or general formula (9) according to claim 8 as a second host.

15. The mixed composition according to claim 14, wherein the difference between the 50% weight loss temperatures of the first host and the second host is within 20°C.

16. A method for producing an organic electroluminescent device according to claim 7, comprising the steps of: premixing the first host and the second host to form a premixed composition; and then depositing a host material containing the premixed composition to form a light-emitting layer.

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