Organic electroluminescent element

Abstract

Provided is a practically useful organic electroluminescent element having low voltage, high efficiency, and long service life characteristics. Specifically, the organic electroluminescent element is provided with a luminous layer containing: a first host of an indolocarbazole derivative represented by general formula (1); a second host of an indolocarbazole derivative represented by general formula (2); and a luminous dopant material. (Ring G is represented by formula (1a), ring H is represented by formula (1b), L1 is a single bond etc., X is N etc., Ar1 and Ar2 are aromatic hydrocarbon groups, aromatic hetero groups, etc., with at least one being a phenyl dibenzofuran group etc. and R1 and R2 represent deuterium etc.) (Ar3 and Ar4 are aromatic hydrocarbon groups etc., L is a single bond etc., and R3, R6, and R7 are deuterium etc.)

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 laws 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 that utilizes 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 level and the triplet level, and is thought to theoretically be able to 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 WO2008 / 056746 WO2018 / 198844 US10333077B2 CN Patent Publication 111 No. 233847 KR Patent Publication No. 2019-0009211 No. KR Patent Publication No. 2019-0001357 No. WO2013 / 122402 No. KR Patent Publication No. 2021-0062771

[0007] Patent Document 3 discloses the use of an indolocarbazole compound as a host material in a light-emitting layer.

[0008] Patent Documents 4 and 5 disclose the use of an indolocarbazole compound and a biscarbazole compound as a mixed host material in a light-emitting layer.

[0009] Patent Documents 6, 7 and 8 disclose the use of an indolocarbazole compound substituted with a phenyldibenzofuran group as a host material in a light-emitting layer.

[0010] Patent Documents 9 and 10 disclose the use of an indolocarbazole compound substituted with a phenyldibenzofuran group and a biscarbazole compound as a mixed host material in a light-emitting layer.

[0011] However, none of these methods are satisfactory, and further improvements are desired.

[0012] 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 regarded 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 a light source, 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, an object of the present invention is to provide a practically useful organic EL element that operates at a low voltage, has high efficiency, and has a long lifespan.

[0013] As a result of extensive investigations, the present inventors have found that an organic electroluminescent device using a specific mixed host material in the light-emitting layer can solve the above problems, and have thus completed the present invention.

[0014] The present invention relates to an organic electroluminescent device comprising one or more emitting layers between an anode and a cathode facing each other, wherein at least one emitting layer contains a first host selected from compounds represented by the following general formula (1), a second host selected from compounds represented by the following general formula (2), and a luminescent dopant material:

[0015] In general formula (1), ring G is an aromatic ring represented by formula (1a) and is fused with two adjacent rings. Ring H is a heterocyclic ring represented by formula (1b) and is fused with two adjacent rings at any position, but is not fused at a side containing N. X is each independently N, C-H, or C-R, and at least one is N. Y is O or S. Ar １ 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 linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon group and the aromatic heterocyclic group are linked together. ２ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon group and the aromatic heterocyclic group are linked together. 1 and two Ar ２ At least one of the groups represented by formula (1c) is a group represented by formula (1c). * indicates the bonding position. 1 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; 1each independently represents 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 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together. １ is an aromatic hydrocarbon group, R １ may be condensed with the benzene ring to which R is bonded to form a ring. ２ each independently represent deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a to f represent the number of substitutions, a and b each independently represent an integer of 0 to 4, c each independently represent an integer of 0 to 2, d each independently represent an integer of 0 to 13, e each independently represent an integer of 0 to 3, and f each independently represent an integer of 0 to 4. n represents the number of repetitions and is an integer of 1 to 4.

[0016]

[0017] In formula (2), Ar ３ , and Ar ４ 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 to 5 aromatic rings 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 ３ , R ６ , and R ７ each independently represent deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. g to j and p to q represent the number of substitutions, g and h each independently represent an integer of 0 to 4, i and j each independently represent an integer of 0 to 3, and p and q each independently represent an integer of 0 to 12.

[0018] In the general formula (1), all of X are N, R １ is deuterium, R ２ In a preferred embodiment of the present invention, either one of the following is satisfied: is deuterium; or Y is O.

[0019] In the general formula (1), Ar２ At least one of the above may be represented by any one of formulas (3) to (5), and the formula (3) is more preferred.

[0020] The compound represented by the general formula (1) may be represented by any one of the following formulas (6) to (9).

[0021] In the compound represented by the general formula (2), Ar ３ , and Ar ４ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 3 aromatic rings of these aromatic groups are linked together, and more preferably a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group. ３ In the compound represented by the general formula (2), Ar is preferably deuterium. ３ , and Ar ４ is a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group, or R ３ is deuterium.

[0022] The compound of the general formula (2) may be represented by the following formula (10).

[0023] The organic electroluminescent device of the present invention has a mixed host containing two types of compounds and an emitting layer containing a dopant (light-emitting dopant material). In the mixed host, the proportion of the compound represented by general formula (1) relative to the total of the compound represented by general formula (1) and the compound represented by general formula (2) is preferably 10 wt% or more but less than 80 wt%, more preferably 20 wt% or more but less than 70 wt%. Furthermore, it is more preferable that the light-emitting dopant 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, or a thermally activated delayed fluorescent dopant.

[0024] The present invention relates to an organic electroluminescent device including an emitting layer containing a host and a luminescent dopant material between an opposing anode and cathode, the emitting layer being a premix containing a first host and a second host, the premix being used to form the emitting layer, the first host being selected from the compounds represented by general formula (1) and the second host being selected from the compounds represented by general formula (2). Furthermore, in manufacturing the organic electroluminescent device, it is preferable to include a step of mixing the first host represented by general formula (1) and the second host represented by general formula (2) to prepare a premix, and then depositing a host material containing the premix to form the emitting layer.

[0025] In the method for producing an organic electroluminescent device, the difference between the 50% weight loss temperatures of the first host and the second host is preferably within 20°C.

[0026] According to the present invention, a first host having an indolocarbazole with a nitrogen-containing six-membered ring and a phenyldibenzofuran group or a phenyldibenzothiophene group is mixed with a biscarbazole compound as a second host, thereby providing an organic EL device that operates at a low voltage, yet has high efficiency and a long lifetime.

[0027] FIG. 1 is a schematic cross-sectional view showing an example of an organic EL element.

[0028] The organic electroluminescent device of the present invention is an organic electroluminescent device having a plurality of organic layers between an anode and a cathode, wherein the organic layers include at least one light-emitting layer, and the light-emitting layer includes a first host represented by the general formula (1), a second host represented by the general formula (2), and a light-emitting dopant material.

[0029] In general formula (1), ring G is an aromatic ring represented by formula (1a) and is fused with two adjacent rings. Ring H is a five-membered heterocycle represented by formula (1b) and is fused with two adjacent rings at any position, but is not fused at 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 (1) is specifically represented by structures such as those of formulas (6) to (9), preferably formulas (7) to (9), and more preferably formula (9).

[0030] In general formula (1) and formulas (6) to (9), common symbols have the same meaning. X's are each independently N, C-H, or C-R, and at least one is N. Preferably, at least two X's are N, and more preferably, all of X's are N.

[0031] In formula (1c) and formulas (3) to (5), the common symbols have the same meaning. Formula (1c) can be represented by formulas (3) to (5), and Ar ２ At least one of the above is preferably represented by any one of formulas (3) to (5), and more preferably represented by formula (3). Each Y is independently O or S, and preferably O.

[0032] a to f represent the number of substitutions, and a, b, and f each independently represent an integer of 0 to 4, c represents an integer of 0 to 2, d represents an integer of 0 to 13, and e represents an integer of 0 to 3. n represents the number of repetitions and is an integer of 1 to 4. Preferably, a and b each independently represent an integer of 1 to 4, c represents an integer of 1 or 2, f each independently represent an integer of 0 or 4, and n represents an integer of 1 or 2, and more preferably, a and b each independently represent an integer of 4, and c represents an integer of 2.

[0033] Ar１ 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, a substituted or unsubstituted linked aromatic group in which 2 to 5 aromatic rings of these aromatic groups are linked together, or a group represented by formula (1c). Preferably, they are substituted or unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, substituted or unsubstituted linked aromatic groups in which 2 to 5 aromatic hydrocarbon groups are linked together, or a group represented by formula (1c). More preferably, they are substituted or unsubstituted phenyl groups or substituted or unsubstituted linked aromatic groups in which 2 to 3 phenyl groups are linked together. The phenyl groups are linked together in a meta- or para-linkage.

[0034] Ar ２ are each independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, a substituted or unsubstituted linked aromatic group in which 2 to 5 aromatic rings of these aromatic groups are linked together, or a group represented by formula (1c). Preferably, they are a substituted or unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, a substituted or unsubstituted linked aromatic group in which 2 to 5 aromatic hydrocarbon groups are linked together, or a group represented by formula (1c). More preferably, they are a substituted or unsubstituted phenyl group, a substituted or unsubstituted linked aromatic group in which 2 to 3 phenyl groups are linked together, or a group represented by formula (1c).

[0035] Ar １ and two Ar ２ At least one of them is a group represented by formula (1c).

[0036] L １ is 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. It is preferably a single bond or a substituted or unsubstituted phenylene group, and the linking mode of the phenylene group may be either meta- or para-linking.

[0037] The above Ar １Specific 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 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, isoxazole, chrys ... Examples of the terphenyl group include groups derived by removing one hydrogen atom from benzoline, 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 5 of these. Preferred examples include groups derived from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, or a compound formed by linking 2 to 5 of these. More preferred are phenyl, biphenyl, and terphenyl groups. The terphenyl group may be linear or branched.

[0038] The above Ar ２Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, the unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or the linked aromatic group in which 2 to 5 aromatic rings of these aromatic groups are linked together include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, pyrene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, Examples of the group include groups derived by removing one hydrogen atom from 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 5 of these. Preferred examples include groups derived from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, pyrene, phenanthrene, fluorene, or a compound formed by linking 2 to 5 of these. More preferred are phenyl, biphenyl, and terphenyl groups. The terphenyl group may be linear or branched.

[0039] L １ When Ar is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, the same applies to the above Ar except that it is a group formed by removing two hydrogen atoms. １ is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. A substituted or unsubstituted phenylene group is preferred.

[0040] R １are each independently 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 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together. Deuterium is preferred, or a substituted or unsubstituted phenyl group. Deuterium is more preferred. Also, R １ is an aromatic hydrocarbon group, R １ may be condensed with the benzene ring to which it is bonded to form a ring.

[0041] R １ 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 linking aromatic group in which 2 to 5 aromatic rings of these aromatic groups are linked together, and specific examples thereof include the above Ar １ This is the same as in the case of

[0042] R ２ are each independently deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, preferably deuterium.

[0043] Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc. Preferred are alkyl groups having 1 to 4 carbon atoms.

[0044] In the general formula (2), 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 formula (10). In general formula (2) and formula (10), the same symbols have the same meanings.

[0045] Ar ３ , and Ar ４each 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 to 5 aromatic rings of these aromatic groups are linked together. Preferred are substituted or unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or linked aromatic groups in which 2 to 3 aromatic rings of the aromatic hydrocarbon groups are linked together, and more preferred are substituted or unsubstituted phenyl groups, substituted or unsubstituted biphenyl groups, and substituted or unsubstituted terphenyl groups. The terphenyl groups may be linked in a linear chain or branched. Note that Ar ３ , and Ar ４ Specific examples of when 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 to 5 of these aromatic rings are linked together are the same as those described above for Ar1.

[0046] 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. Specific examples of when L is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms or an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms are the same as those described above for Ar1, except that L is a group formed by removing two hydrogen atoms.

[0047] R ３ , R ６ and R ７ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, preferably deuterium. Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms are the same as those described above for R2.

[0048] g to j and p to q represent the number of substitutions, and g and h each independently represent an integer of 0 to 4, i and j each independently represent an integer of 0 to 3, and p and q each independently represent an integer of 0 to 12. Preferably, g and h each independently represent an integer of 1 to 4, i and j each independently represent an integer of 1 to 3, and p and q each independently represent an integer of 1 to 12, and more preferably, g and h each independently represent an integer of 4, and i and j each independently represent an integer of 3.

[0049] 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.

[0050] 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 substitutes 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.

[0051] 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.

[0052] 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 (2) and formulas (6) to (10) may be deuterium atoms. Furthermore, the deuterated compound may be a single compound or a mixture of two or more compounds. Specifically, a deuteration rate of 50% means that on average, half of all hydrogen atoms have been substituted with deuterium atoms, and the deuterated compound may be a single compound or a mixture of compounds with different deuteration rates.

[0053] When part of the hydrogen atoms in the compounds represented by the general formulas (1) to (2) and formulas (6) to (10) are deuterium, preferably 20% or more of the hydrogen atoms are deuterium, more preferably 40% or more, and even more preferably 50% or more.

[0054] 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.

[0055] Specific examples of the compound represented by the general formula (1) are shown below, but the compound is not limited to these exemplary compounds.

[0056]

[0057] Specific examples of the compound represented by the general formula (2) are shown below, but the compound is not limited to these exemplary compounds.

[0058]

[0059]

[0060] The host material for the organic EL device of the present invention is suitably used as a host material for the light-emitting layer.

[0061] 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.

[0062] FIG. 1 is a cross-sectional view showing an example of the structure of a typical organic EL device used in the present invention, 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] - 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.

[0067] 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.

[0068] -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.

[0069] The host material used is a host material represented by any one of the general formulae (1), (6) to (9) (also referred to as the host material of the present invention). The host material of the present invention may be one type, or two or more different compounds, or may be a combination of one or more other host materials, such as known host materials. The other host material is preferably a compound that has hole-transporting and electron-transporting capabilities, prevents the emission wavelength from shifting to longer wavelengths, and has a high glass transition temperature.

[0070] When the host material of the present invention is contained as the first host material, it is particularly preferable to use a compound represented by any one of the general formulas (2) and (10) as the second host material, but other host materials shown below may also be used as the second host. Furthermore, when the host material of the present invention is used as the first host material and a compound represented by any one of the general formulas (2) and (10) is used as the second host material, other host materials may also be used as the third host material.

[0071] 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.

[0072] Specific examples of the other host materials are shown below, but are not limited to these.

[0073] The organic light-emitting dopant material is preferably a phosphorescent dopant, a fluorescent dopant, or a thermally activated delayed fluorescent dopant.

[0074] 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.

[0075] The phosphorescent dopant material may be contained in the light-emitting layer alone or in combination of two or more kinds. 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.

[0076] The phosphorescent dopant material is not particularly limited, but specific examples include the following.

[0077]

[0078] 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.

[0079] 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.

[0080] 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.

[0081] The thermally activated delayed fluorescent dopant material is not particularly limited, but specific examples include the following.

[0082]

[0083] 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.

[0084] 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.

[0085] -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.

[0086] - 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.

[0087] 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.

[0088] -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.

[0089] 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).

[0090] -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.

[0091] 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.

[0092] - 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.

[0093] 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.

[0094] The method for manufacturing an organic electroluminescent device of the present invention includes a step of premixing the first host material and the second host material, and a step of depositing the resulting mixture from a single deposition source to form an emitting layer. By premixing the two host materials in this manner, the performance of the organic EL device can be improved. Powder mixing or melt mixing can be used as the mixing method.

[0095] In the composition obtained by the above pre-mixing, 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.

[0096] 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.

[0097] As representative examples, the synthesis of Compounds 1-1, 1-3, 1-8, 1-13, 1-29, 1-44, 1-55, and 1-57 is shown below. Other compounds were synthesized using similar methods. The deuteration ratio was determined by proton nuclear magnetic resonance spectroscopy.

[0098] Synthesis Example 1 To 7.0 g (13.4 mmol) of compound (a), 5.0 g (13.5 mmol) of compound (b), 0.12 g (0.21 mmol) of CX21, 3.2 g (30.2 mmol) of sodium carbonate, 250 mL of toluene, 100 mL of ethanol, and 20 mL of water were added and stirred at 75 °C for 2 hours under a nitrogen atmosphere. After cooling to room temperature, 50 mL of water was added, and the organic phase was extracted with toluene. The organic phase was dried over MgSO4 and concentrated to dryness, yielding 10.7 g of a yellow solid. The resulting solid was purified by silica gel column chromatography and crystallization to yield 3.5 g (4.80 mmol, 36% yield) of compound (1-1) as a yellow solid (APCI-TOFMS, m / z 730 [M+H] + ).

[0099] Synthesis Example 2 To 5.9 g (9.86 mmol) of compound (c), 3.6 g (9.72 mmol) of compound (b), 2.3 g (21.7 mmol) of sodium carbonate, 80 mg (0.14 mmol) of CX21, 80 g of m-xylene, 40 g of ethanol, and 8.0 g of water were added and stirred at 110 °C under a nitrogen atmosphere for 2.5 hours. After cooling to room temperature, 50 mL of water was added, and the organic phase was extracted with toluene, dried over MgSO4, and concentrated to dryness to obtain 7.7 g of a yellow solid. Purification by silica gel column chromatography yielded 5.4 g (6.70 mmol, 68% yield) of compound (1-3) as a yellow solid (APCI-TOFMS, m / z 806 [M+H] + ).

[0100] Synthesis Example 3 To 39.0 g (75 mmol) of compound (a), 15 g (75 mmol) of compound (e), 4.3 g (3.75 mmol) of tetrakistriphenylphosphinepalladium(0), 48.8 g (150 mmol) of cesium carbonate, and 500 mL of 1,4-dioxane were added and stirred at 110 °C under a nitrogen atmosphere for 4 hours. After cooling to room temperature, the reaction mixture was added to 1 L of water, and the resulting yellow solid was purified by silica gel column chromatography to give 15.2 g (24 mmol, 32% yield) of intermediate (f) as a yellow solid. Next, to 4.3 g (6.75 mmol) of the resulting intermediate (f), 2.5 g (6.75 mmol) of compound (b), 57.9 mg (0.10 mmol) of Cx21, 1.8 g (13.5 mmol) of potassium carbonate, 18.7 g of water, and 145 g of m-xylene were added and stirred overnight at 110 °C under a nitrogen atmosphere. After cooling to room temperature, 50 mL of water was added, and the organic phase was extracted with toluene, dried over MgSO4, and concentrated to dryness to obtain 2.7 g of a yellow solid. Purification was carried out by silica gel column chromatography to obtain 1.2 g (1.49 mmol, 22% yield) of compound (1-13) as a yellow solid (APCI-TOFMS, m / z 806 [M+H] + ).

[0101] Synthesis Example 4 To 10.0 g (29.6 mmol) of compound (g), 100 mL of deuterated benzene (CD6) and 30.0 g (200 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 (200 mL) of sodium carbonate (23.0 g) and quenched. After separation and purification, 8.7 g (25.0 mmol, 84% yield, 93% deuteration rate) of the deuterated product, compound (h), was obtained.

[0102] Synthesis Example 5 Under a nitrogen atmosphere, 0.8 g of 60 wt% sodium hydride was added to 100 mL of N,N'-dimethylacetamide to prepare a suspension. 5.0 g (14.4 mmol) of intermediate (h) dissolved in 160 mL of N,N'-dimethylacetamide was added and stirred for 30 minutes. 4.1 g (18.1 mmol) of compound (i) was added and stirred for 1 hour. The reaction solution was added to a mixture of distilled water (500 mL) with stirring, and the resulting precipitate was collected by filtration. The resulting solid was purified by silica gel column chromatography and crystallization to obtain 3.9 g (7.26 mmol, 50% yield) of compound (j) as a yellow solid. Next, 2.0 g (3.72 mmol) of the resulting intermediate (j) was mixed with 1.5 g (4.09 mmol) of compound (b), 31.9 mg (0.056 mmol) of Cx21, 1.0 g (7.44 mmol) of potassium carbonate, 10.3 g of water, and 80.0 g of m-xylene, and the mixture was stirred overnight at 110 °C under a nitrogen atmosphere. After cooling to room temperature, 50 mL of water was added, and the organic phase was extracted with toluene, dried over MgSO4, and concentrated to dryness, yielding 3.1 g of a yellow solid. Purification by silica gel column chromatography yielded 1.6 g (2.15 mmol, 58% yield, 43% deuteration) of compound (1-29) as a yellow solid (APCI-TOFMS, m / z 745 [M+H] + ).

[0103] Synthesis Example 6 To 2.8 g (5.36 mmol) of compound (a), 2.0 g (5.40 mmol) of compound (k), 50 mg (0.087 mmol) of CX21, 1.3 g (12.3 mmol) of sodium carbonate, 100 mL of toluene, 40 mL of ethanol, and 10 mL of water were added and stirred at 75 °C for 2 hours under a nitrogen atmosphere. After cooling to room temperature, 20 mL of water was added, and the organic phase was extracted with toluene. The organic phase was dried over MgSO4 and concentrated to dryness, yielding 3.4 g of a yellow solid. The resulting solid was purified by silica gel column chromatography and crystallization to yield 1.0 g (1.37 mmol, 26% yield) of compound (1-55) as a yellow solid (APCI-TOFMS, m / z 730 [M+H]+ ).

[0104] Synthesis Example 7 To 4.3 g (16.9 mmol) of compound (n), 6.0 g (18.6 mmol) of compound (o), 0.32 g (1.68 mmol) of copper(I) iodide, 0.49 g (3.38 mmol) of 8-hydroxyquinoline, 4.7 g (34.0 mmol) of potassium carbonate, and 300 mL of 1,3-dimethyl-2-imidazolidinone were added and stirred overnight at 140 °C under a nitrogen atmosphere. After cooling to room temperature, the reaction solution was added to a mixture of distilled water (500 mL) with stirring, and the resulting solid was collected by filtration. The resulting solid was purified by silica gel column chromatography and crystallization to obtain 3.38 g (6.78 mmol, 40% yield) of intermediate (p) as a white solid. Next, under a nitrogen atmosphere, 0.24 g of 60 wt% sodium hydride was added to 40 mL of N,N'-dimethylacetamide to prepare a suspension. To this was added 2.0 g (4.01 mmol) of intermediate (p) dissolved in 100 mL of N,N'-dimethylacetamide, and the mixture was stirred for 30 minutes. To this was added 1.7 g (4.81 mmol) of compound (q), and the mixture was stirred for 1 hour. The reaction solution was added to a mixture of methanol (100 mL) and distilled water (25 mL) with stirring, and the resulting precipitate was collected by filtration. The resulting solid was purified by silica gel column chromatography and crystallized to give 0.97 g (1.20 mmol, 30% yield) of compound 1-57 as a yellow solid (APCI-TOFMS, m / z 806 [M+H] + ).

[0105] Synthesis Example 8 To 12.0 g (23.0 mmol) of compound (a), 7.9 g (27.4 mmol) of compound (r), 0.20 g (0.34 mmol) of CX21, 5.5 g (51.7 mmol) of sodium carbonate, 500 g of toluene, 300 g of ethanol, and 50 g of water were added and stirred at 75 °C for 16 hours under a nitrogen atmosphere. After cooling to room temperature, 100 mL of water was added, and the organic phase was extracted with toluene. The organic phase was dried over MgSO4 and concentrated to dryness, yielding 17.0 g of a pale yellow solid. The resulting solid was purified by silica gel column chromatography and crystallization to yield 7.1 g (9.74 mmol, 42% yield) of compound (1-44) as a yellow solid (APCI-TOFMS, m / z 730 [M+H]+).

[0106] Synthesis Example 9 Under a nitrogen atmosphere, 1.1 g of 60 wt% sodium hydride was added to 30 mL of N,N'-dimethylacetamide to prepare a suspension. 9.9 g (19.9 mmol) of intermediate (p) dissolved in 170 mL of N,N'-dimethylacetamide was added and stirred for 30 minutes. 6.4 g (23.9 mmol) of compound (s) was added and stirred for 1 hour. The reaction solution was poured into a mixture of methanol (500 mL) and distilled water (500 mL) with stirring, and the resulting precipitate was collected by filtration. 13.6 g of the resulting solid was purified by silica gel column chromatography and crystallized to give 11.3 g (15.5 mmol, 78% yield) of compound 1-8 as a yellow solid (APCI-TOFMS, m / z 730 [M+H]+).

[0107] Synthesis Example 10 To 3.0 g (7.10 mmol) of compound (t), 2.0 g (8.58 mmol) of compound (u), 100 mL of m-xylene, 0.2 g (0.39 mmol) of bis(tri-tert-butylphosphine)palladium, and 4.9 g (35.5 mmol) of potassium carbonate were added and stirred under nitrogen atmosphere and reflux for 5 hours. After cooling, the reaction mixture was separated and purified to obtain 1.5 g (2.61 mmol, 37% yield, 46% deuteration) of compound (2-109) as a white solid. (APCI-TOFMS, m / z 575 [M+H]+)

[0108] Synthesis Example 11 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, 2.5 g (4.25 mmol, 29% yield, 79% deuteration) of compound (2-116) was obtained as a white solid (APCI-TOFMS, m / z 589 [M+H]+).

[0109] Compound 1-32, a deuterated product, was synthesized by carrying out the reaction in the same manner as in Synthesis Example 4. The deuteration rate of Compound 1-32 was calculated in the same manner as in Compound 1-29, and was found to be 90%.

[0110] Compound 2-118, a deuterated product, was synthesized by carrying out the reaction in the same manner as in Synthesis Example 11. The deuteration rate of compound 2-118 was calculated in the same manner as for compounds 2-109 and 2-116, and was found to be 71%.

[0111] The compounds used in the examples and comparative examples are shown below.

[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 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 1-1 as the first host, compound 2-2 as the second host, and Ir(ppy)3 as the emitting dopant were co-deposited from different evaporation sources to form a 40 nm-thick emitting layer. The co-deposition conditions were an Ir(ppy)3 concentration of 10 wt% and a weight ratio of the first host to the second host of 30:70. 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.

[0113] Examples 2 to 21 Organic EL devices were prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used as the first host and the second host in the weight ratio shown in Table 1.

[0114] Examples 22 to 26 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 1 were weighed out so as to have the weight ratio shown in Table 1, and mixed while grinding in a mortar to obtain a preliminary mixture, and then vapor-deposited from a single vapor deposition source.

[0115] Comparative Examples 1 to 6 Organic EL devices were prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used as the first host and the second host in the weight ratios shown in Table 1.

[0116] Comparative Examples 7 to 12 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 1 were weighed out so as to have the weight ratio shown in Table 1, and mixed while being ground in a mortar to obtain a preliminary mixture, and the resulting mixture was evaporated from a single evaporation source.

[0117] The evaluation results of the fabricated organic EL devices are shown in Table 1. 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. 2The 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.

[0118]

[0119] The results in Table 1 show that Examples 1 to 26 have improved power efficiency or life span compared to the comparative example, and exhibit favorable characteristics.

[0120] Table 2 shows the 50% weight loss temperature (T 50 ) is written.

[0121]

[0122] According to the present invention, a first host having an indolocarbazole with a nitrogen-containing six-membered ring and a phenyldibenzofuran group or a phenyldibenzothiophene group is mixed with a biscarbazole compound as a second host, thereby providing an organic EL device that operates at a low voltage, yet has high efficiency and a long lifetime.

[0123] 1 Substrate, 2 Anode, 3 Hole injection layer, 4 Hole transport layer, 5 Light-emitting layer, 6 Electron transport layer, 7 Cathode

Claims

1. The organic electroluminescent device includes one or more light-emitting layers between an anode and a cathode facing each other, and is characterized in that at least one of the light-emitting layers contains a first host selected from compounds represented by the following general formula (1), a second host selected from compounds represented by the following general formula (2), and a light-emitting dopant material: 【Chemistry 1】 (Here, ring G is an aromatic ring represented by formula (1a) and is fused to two adjacent rings. Ring H is a heterocycle represented by formula (1b) and is fused to two adjacent rings at any position, but is not fused at a side containing N. Each X is independently N, C-H, or C-R, and at least one is N. Y is O or S. Ar １ 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 linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups are linked together. Ar ２ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or an unsubstituted linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon group and the aromatic heterocyclic group are linked in a linear chain, provided that Ar １ and two Ar ２ At least one of these represents a group represented by formula (1c), and * represents the bonding position. L １ 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 １ each independently represents 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 linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups are linked together. １ is an aromatic hydrocarbon group, R １ may be condensed with the benzene ring to which it is bonded to form a ring. R ２ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a to f represent the number of substitutions, a and b each independently represent an integer of 0 to 4, c each independently represent an integer of 0 to 2, d each independently represent an integer of 0 to 13, e each independently represent an integer of 0 to 3, and f each independently represent an integer of 0 to 4. n represents the number of repetitions and is an integer of 1 to 4. 【Chemistry 2】 (wherein, Ar ３ , and Ar ４ 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 to 5 aromatic rings 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 ３ , R ６ , and R ７ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms; g to j and p to q each independently represent the number of substitutions; g and h each independently represent an integer of 0 to 4; i and j each independently represent an integer of 0 to 3; and p and q each independently represent an integer of 0 to 12.

2. The organic electroluminescent device according to claim 1 , wherein all of the X's are N.

3. The Ar ２ 2. The organic electroluminescent device according to claim 1, wherein at least one of the above is represented by any one of formulas (3) to (5). 【Chemistry 3】 (Here, *, Y, R ２ , e, f and n are the same as those in formula (1c).

4. The Ar ２ The organic electroluminescent device according to claim 3 , wherein at least one of the above is a group represented by formula (3).

5. The organic electroluminescent device according to claim 1 , wherein the Y is O.

6. 2. The organic electroluminescent device according to claim 1, wherein the compound represented by the general formula (1) is represented by any one of the following formulas (6) to (9): 【Chemistry 4】 (Here, Ar １ , Ar ２ , L １ , R １ , R ２ , a, b, c and d are the same as those in formula (1).

7. The above-mentioned R １ The organic electroluminescent device according to claim 1, wherein R is deuterium.

8. The R ２ 2. The organic electroluminescent device according to claim 1, wherein is deuterium.

9. 2. The organic electroluminescent device according to claim 1, wherein the general formula (2) is represented by the following formula (10): 【Chemistry 5】 (wherein, Ar ３ , Ar ４ , L, R ３ , R ６ , R ７ , g to j, and p to q are the same as in formula (2).

10. The Ar ３ and Ar ４ 2. The organic electroluminescent device according to claim 1, 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.

11. The R ３ 2. The organic electroluminescent device according to claim 1, wherein is deuterium.

12. 12. The organic electroluminescent device according to claim 1, wherein the light-emitting 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. 12. The organic electroluminescent device according to claim 1, wherein the light-emitting dopant material is a thermally activated delayed fluorescent dopant material.

14. In an organic electroluminescent device comprising an emitting layer containing a host and a luminescent dopant material between an anode and a cathode facing each other, a pre-mixture containing a first host and a second host is used to form the emitting layer, the pre-mixture being characterized in that the first host is selected from compounds represented by the following general formula (1), and the second host is selected from compounds represented by the following general formula (2): 【Chemistry 6】 (Here, ring G is an aromatic ring represented by formula (1a), and ring H is a heterocyclic ring represented by formula (1b). Each X is independently N, C--H, or C--R, and at least one is N. Y is 0 or S. Ar １ 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 linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups are linked together. Ar ２ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 17 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or an unsubstituted linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon group and the aromatic heterocyclic group are linked in a linear chain, provided that Ar １ and two Ar ２ At least one of these is a group represented by formula (1c). 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 １ each independently represents 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 linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups are linked together. １ is an aromatic hydrocarbon group, R １ may be condensed with the benzene ring to which R is bonded to form a ring. ２ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a to f represent the number of substitutions, a and b each independently represent an integer of 0 to 4, c each independently represent an integer of 0 to 2, d each independently represent an integer of 0 to 13, e each independently represent an integer of 0 to 3, and f each independently represent an integer of 0 to 4. n represents the number of repetitions and is an integer of 1 to 4. 【Chemistry 7】 (wherein, Ar ３ , and Ar ４ each independently represents an aromatic hydrocarbon group having 6 to 18 carbon atoms, an 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 ３ , R ６ and R ７ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms; g to j and p to q each independently represent the number of substitutions; g and h each independently represent an integer of 0 to 4; i and j each independently represent an integer of 0 to 3; and p and q each independently represent an integer of 0 to 12.

15. 15. The premix 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. In producing the organic electroluminescent device according to any one of claims 1 to 13, a method for producing an organic electroluminescent device, comprising the steps of: mixing the first host and the second host to prepare a preliminary mixture; and then depositing a host material containing the preliminary mixture to form a light-emitting layer.

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