Patent Application
20220289718
The present invention relates to materials for use in electronic devices, especially in organic electroluminescent devices, and to electronic devices, especially organic electroluminescent devices comprising these materials.
Emitting materials used in organic electroluminescent devices are frequently phosphorescent organometallic complexes. For quantum-mechanical reasons, up to four times the energy efficiency and power efficiency is possible using organometallic compounds as phosphorescence emitters. In electroluminescent devices, especially also in electroluminescent devices that exhibit triplet emission (phosphorescence), there is generally still a need for improvement. The properties of phosphorescent electroluminescent devices are not just determined by the triplet emitters used. More particularly, the other materials used, such as matrix materials, are also of particular significance here. Improvements in these materials can thus also lead to distinct improvements in the properties of the electroluminescent devices.
WO 2010/136109 discloses indenocarbazole derivatives as matrix materials for phosphorescent emitters. There is no disclosure of compounds according to the present invention.
In general terms, in the case of these materials, for example for use as matrix materials, there is still a need for improvement, particularly in relation to the lifetime, but also in relation to the efficiency and operating voltage of the device.
The problem addressed by the present invention is therefore that of providing compounds which are suitable for use in an organic electronic device, especially in an organic electroluminescent device, and which lead to good device properties when used in this device, and that of providing the corresponding electronic device.
More particularly, the problem addressed by the present invention is that of providing compounds which lead to a high lifetime, good efficiency and low operating voltage. Particularly the properties of the matrix materials too have a major influence on the lifetime and efficiency of the organic electroluminescent device.
A further problem addressed by the present invention can be considered that of providing compounds suitable for use in a phosphorescent or fluorescent electroluminescent device, especially as a matrix material. A particular problem addressed by the present invention is that of providing matrix materials that are suitable for red- and yellow-phosphorescing electroluminescent devices, especially for red-phosphorescing electroluminescent devices, and if appropriate also for blue-phosphorescing electroluminescent devices.
In addition, the compounds, especially when they are used as matrix materials, as hole blocker materials or as electron transport materials in organic electroluminescent devices, were to lead to devices having excellent colour purity.
A further object can be considered that of providing electronic devices having excellent performance at minimum cost and in constant quality.
Furthermore, it should be possible to use or adapt the electronic devices for many purposes. More particularly, the performance of the electronic devices should be maintained over a broad temperature range.
It has been found that, surprisingly, particular compounds described in detail below solve this problem and are of good suitability for use in electroluminescent devices and lead to improvements in the organic electroluminescent device, especially in relation to lifetime, colour purity, efficiency and operating voltage. The present invention therefore provides these compounds and electronic devices, especially organic electroluminescent devices, comprising such compounds.
The present invention provides a compound of formula (1)
where the symbols and indices used are as follows:
An aryl group in the context of this invention contains 6 to 40 carbon atoms; a heteroaryl group in the context of this invention contains 2 to 40 carbon atoms and at least one heteroatom, with the proviso that the sum total of carbon atoms and heteroatoms is at least 5. The heteroatoms are preferably selected from N, O and/or S. Here, an aryl group or heteroaryl group is understood to mean either a simple aromatic ring, i.e. benzene, or a simple heteroaromatic ring, for example pyridine, pyrimidine, thiophene, etc., or a condensed (fused) aryl or heteroaryl group, for example naphthalene, anthracene, phenanthrene, quinoline, isoquinoline, etc.
Aromatic systems joined to one another by a single bond, for example biphenyl, by contrast, are not referred to as an aryl or heteroaryl group but as an aromatic ring system.
An electron-deficient heteroaryl group in the context of the present invention is a heteroaryl group having at least one heteroaromatic six-membered ring having at least one nitrogen atom. Further aromatic or heteroaromatic five-membered or six-membered rings may be fused onto this six-membered ring. Examples of electron-deficient heteroaryl groups are pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, quinazoline or quinoxaline.
An aromatic ring system in the context of this invention contains 6 to 60 carbon atoms in the ring system. A heteroaromatic ring system in the context of this invention contains 2 to 60 carbon atoms and at least one heteroatom in the ring system, with the proviso that the sum total of carbon atoms and heteroatoms is at least 5. The heteroatoms are preferably selected from N, O and/or S. An aromatic or heteroaromatic ring system in the context of this invention shall be understood to mean a system which does not necessarily contain only aryl or heteroaryl groups, but in which it is also possible for two or more aryl or heteroaryl groups to be joined by a nonaromatic unit, for example a carbon, nitrogen or oxygen atom. For example, systems such as fluorene, 9,9′-spirobifluorene, 9,9-diarylfluorene, triarylamine, diaryl ethers, stilbene, etc. shall also be regarded as aromatic ring systems in the context of this invention, and likewise systems in which two or more aryl groups are joined, for example, by a short alkyl group. Preferably, the aromatic ring system is selected from fluorene, 9,9′-spirobifluorene, 9,9-diarylamine or groups in which two or more aryl and/or heteroaryl groups are joined to one another by single bonds.
In the context of the present invention, an aliphatic hydrocarbyl radical or an alkyl group or an alkenyl or alkynyl group which may contain 1 to 20 carbon atoms and in which individual hydrogen atoms or CH2 groups may also be substituted by the abovementioned groups is preferably understood to mean the methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, neopentyl, cyclopentyl, n-hexyl, neohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl, trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl or octynyl radicals. An alkoxy group having 1 to 40 carbon atoms is preferably understood to mean methoxy, trifluoromethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, s-pentoxy, 2-methylbutoxy, n-hexoxy, cyclohexyloxy, n-heptoxy, cycloheptyloxy, n-octyloxy, cyclooctyloxy, 2-ethylhexyloxy, pentafluoroethoxy and 2,2,2-trifluoroethoxy. A thioalkyl group having 1 to 40 carbon atoms is understood to mean especially methylthio, ethylthio, n-propylthio, i-propylthio, n-butylthio, i-butylthio, s-butylthio, t-butylthio, n-pentylthio, s-pentylthio, n-hexylthio, cyclohexylthio, n-heptylthio, cycloheptylthio, n-octylthio, cyclooctylthio, 2-ethylhexylthio, trifluoromethylthio, pentafluoroethylthio, 2,2,2-trifluoroethylthio, ethenylthio, propenylthio, butenylthio, pentenylthio, cyclopentenylthio, hexenylthio, cyclohexenylthio, heptenylthio, cycloheptenylthio, octenylthio, cyclooctenylthio, ethynylthio, propynylthio, butynylthio, pentynylthio, hexynylthio, heptynylthio or octynylthio. In general, alkyl, alkoxy or thioalkyl groups according to the present invention may be straight-chain, branched or cyclic, where one or more nonadjacent CH2 groups may be replaced by the abovementioned groups; in addition, it is also possible for one or more hydrogen atoms to be replaced by D, F, Cl, Br, I, CN or NO2, preferably F, Cl or CN, further preferably F or CN, especially preferably CN.
An aromatic or heteroaromatic ring system which has 5-60 or 5-40 aromatic ring atoms and may also be substituted in each case by the abovementioned radicals and which may be joined to the aromatic or heteroaromatic system via any desired positions is understood to mean especially groups derived from benzene, naphthalene, anthracene, benzanthracene, phenanthrene, pyrene, chrysene, perylene, fluoranthene, naphthacene, pentacene, benzopyrene, biphenyl, biphenylene, terphenyl, triphenylene, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene, cis- or trans-indenocarbazole, cis- or trans-indolocarbazole, truxene, isotruxene, spirotruxene, spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, oxazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, hexaazatriphenylene, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, 1,5-diazaanthracene, 2,7-diazapyrene, 2,3-diazapyrene, 1,6-diazapyrene, 1,8-diazapyrene, 4,5-diazapyrene, 4,5,9,10-tetraazaperylene, pyrazine, phenazine, phenoxazine, phenothiazine, fluorubine, naphthyridine, azacarbazole, benzocarboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole, or groups derived from combinations of these systems.
The wording that two or more radicals together may form a ring, in the context of the present description, should be understood to mean, inter alia, that the two radicals are joined to one another by a chemical bond with formal elimination of two hydrogen atoms. This is illustrated by the following scheme:
In addition, however, the abovementioned wording should also be understood to mean that, if one of the two radicals is hydrogen, the second radical binds to the position to which the hydrogen atom was bonded, forming a ring. This shall be illustrated by the following scheme:
In a preferred configuration, the compounds of the invention may be selected from the compounds of the formulae (1a), (1b), (1c), (1d), (1e), (1f), (1g), (1h), (1i), (1j), (1k), (1l) and (1m)
where o, Y, X, HetAr, R, R1 and R2 have the definitions given above, especially for formula (1). Preference is given here to compounds of the formulae (1a), (1b), (1c), particular preference to compounds of the formula (1c).
It may preferably be the case that, in compounds of the formulae (1), (1a), (1b), (1c), (1d), (1e), (1f), (1g), (1h), (1i), (1j), (1k), (1l) and (1m), not more than four and preferably not more than two X groups are N; more preferably, all X groups are CR, where preferably not more than 4, more preferably not more than 3 and especially preferably not more than 2 of the CR groups that X represents are not the CH group.
It may further be the case that, in compounds of the formulae (1), (1a), (1b), (1c), (1d), (1e), (1f), (1g), (1h), (1i), (1j), (1k), (1l) and (1 m), not more than one X1 group is N; more preferably, all X1 groups are CR, where preferably not more than 3 and more preferably not more than 2 of the CR groups that X1 represents are not the CH group.
According to the position in which the group of the formula (2) is fused on, the invention encompasses the compounds of the following formulae (3), (4) and (5):
where o, HetAr, R, R1 and R2 have the definitions given above, especially for formula (1), and the index r is the same or different at each instance and is 0, 1, 2, 3, 4, 5 or 6, preferably 0 or 1 and very preferably 0, the index n is 0, 1, 2, 3 or 4, preferably 0 or 1 and very preferably 0, and the index m is 0, 1 or 2, preferably 0 or 1 and very preferably 0. Preference is given here to compounds of the formula (3).
The sum total of the indices m, n, o and r in compounds of the formulae (3), (4) and (5) is preferably not more than 6, especially preferably not more than 4 and more preferably not more than 2.
In a preferred embodiment of the invention, the compounds of the formulae (3), (4) and (5) are selected from the compounds of the following formulae (3a-1), (3a-2), (4a-1), (4a-2), (5a-1) and (5a-2):
where o, HetAr, R and R1 have the definitions given above, especially for formula (1). Preference is given here to compounds of the formulae (3a-1) and (3a-2).
More preferably, the compounds of the formulae (3), (4) and (5) are selected from the compounds of the following formulae (3b), (4b) and (5b):
where o, HetAr, R and R1 have the definitions given above, especially for formula (1). Preference is given here to compounds of the formula (3b).
It may further be the case that the substituents R, R1, R2 and R3 according to the above formulae do not form a fused aromatic or heteroaromatic ring system, preferably any fused ring system, with the ring atoms of the ring system. This includes the formation of a fused ring system with possible substituents R4, R5 which may be bonded to the R, R1, R2, R3 radicals.
When two radicals that may especially be selected from R1, R2, R3, R4, R5, R6 and/or R7 form a ring system with one another, this ring system may be mono- or polycyclic, aliphatic, heteroaliphatic, aromatic or heteroaromatic. In this case, the radicals which together form a ring system may be adjacent, meaning that these radicals are bonded to the same carbon atom or to carbon atoms directly bonded to one another, or they may be further removed from one another. In addition, the ring systems provided with the substituents R1, R2, R3, R4, R5, R6 and/or R7 may also be joined to one another via a bond, such that this can bring about a ring closure. In this case, each of the corresponding bonding sites has preferably been provided with a substituent R1, R2, R3, R4, R5, R6 and/or R7.
In addition, it is a feature of preferred compounds of the invention that they are sublimable. These compounds generally have a molar mass of less than about 1200 g/mol.
As described above, HetAr is an electron-deficient heteroaryl group which has 6 to 18 aromatic ring atoms and may be substituted by one or more R3 radicals. In a preferred embodiment of the invention, HetAr has 6 to 14 aromatic ring atoms, more preferably 6 to 10 aromatic ring atoms, where HetAr may in each case be substituted by one or more R3 radicals. In a preferred embodiment of the invention, the R3 radicals on the HetAr group do not form a ring system with one another. In a further preferred embodiment of the invention, an R3 radical together with the naphthylene group to which HetAr binds forms a ring system, more preferably a ring system having 16 to 21, preferably 16 or 17, ring atoms, where this number of ring atoms includes the naphthylene group and the HetAr radical.
In one embodiment, the HetAr radical together with the naphthylene group to which the HetAr radical binds forms an aromatic, heteroaromatic, aliphatic or heteroaliphatic ring system. If the HetAr radical together with the naphthylene group to which the HetAr radical binds forms an aromatic, heteroaromatic, aliphatic or heteroaliphatic ring system, this is a ring system having 16 to 21, preferably 16 or 17, ring atoms, where this number of ring atoms includes the naphthylene group and the HetAr radical.
Preferably, the HetAr group is selected from the structures of the following formulae (HetAr-1) to (HetAr-8):
where the dotted bond represents the bond to the naphthylene group, and the other symbols are as follows:
At the same time, preferably not more than two nitrogen atoms are bonded directly to one another. More preferably, no nitrogen atoms are bonded directly to one another.
It may further be the case that the HetAr group is selected from the structures of the following formula (HetAr-9):
where X2 has the definitions given above, especially for the (HetAr-1) group, the dotted bond represents the bond to the naphthylene group, Ar is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R4 radicals, and R4 has the definitions given above, especially for formula (1).
In a preferred embodiment of the invention, HetAr has two or three nitrogen atoms. It is preferable here for formula (HetAr-1) when it represents a pyrimidine group or a 1,3,5-triazine group. For the formulae (HetAr-2), (HetAr-3) and (HetAr-4), it is preferable when these have two nitrogen atoms. More preferably, the formulae (HetAr-2) and (HetAr-4) represent quinazoline groups.
Preference is given to the groups of the formulae (HetAr-1), (HetAr-2) and (HetAr-3), particular preference to the groups of the formulae (HetAr-1) and (HetAr-2).
Preferred embodiments of the (HetAr-1) group are the groups of the formulae (HetAr-1a) to (HetAr-1d), preferred embodiments of the (HetAr-2) group are the groups of the formulae (HetAr-2a) and (HetAr-2b), preferred embodiments of the (HetAr-3) group are the groups of the formula (HetAr-3a), preferred embodiments of the (HetAr-4) group are the groups of the formula (HetAr-4a), preferred embodiments of the (HetAr-5) group are the groups of the formula (HetAr-5a), preferred embodiments of the (HetAr-6) group are the groups of the formulae (HetAr-6a) to (HetAr-6c), preferred embodiments of the (HetAr-7) group are the groups of the formulae (HetAr-7a) to (HetAr-7c), and preferred embodiments of the (HetAr-8) group are the groups of the formulae (HetAr-8a) to (HetAr-8c),
where Ar is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R4 radicals, and the further symbols have the definitions given above.
In a preferred embodiment of the present invention, the compounds are selected from the formula (4), (4a-1), (4a-2) or (4b), where HetAr is selected from the formulae (HetAr-1) and (HetAr-2), preferably from the formulae (HetAr-1a) to (HetAr-2b), very preferably from the formulae (HetAr-1a) to (HetAr-1d) and most preferably from the formula (HetAr-1d), it being further preferable when Ar in the formulae (HetAr-1) to (HetAr-2) and (HetAr-1a) to (HetAr-1d) given represents an aromatic ring system which has 6 to 40 ring atoms and may be substituted by one or more R4 radicals, it being very preferable when Ar is a phenyl, biphenyl, terphenyl or a quaterphenyl, where the Ar groups mentioned may be substituted by one or more R4 radicals and R4 has the definition given above.
In another preferred embodiment of the present invention, the compounds are selected from the formula (5), (5a-1), (5a-2) or (5b), where HetAr is selected from the formulae (HetAr-1) and (HetAr-2), preferably from the formulae (HetAr-1a) to (HetAr-2b), very preferably from the formulae (HetAr-1a) to (HetAr-1d) and most preferably from the formula (HetAr-1d), it being further preferable when Ar in the formulae (HetAr-1) to (HetAr-2) and (HetAr-1a) to (HetAr-1d) given represents an aromatic ring system which has 6 to 40 ring atoms and may be substituted by one or more R4 radicals, it being very preferable when Ar is a phenyl, biphenyl, terphenyl or a quaterphenyl, where the Ar groups mentioned may be substituted by one or more R4 radicals and R4 has the definition given above.
In a very preferred embodiment of the present invention, the compounds are selected from the formula (3), (3a-1), (3a-2) or (3b), where HetAr is selected from the formulae (HetAr-1) and (HetAr-2), preferably from the formulae (HetAr-1a) to (HetAr-2b), very preferably from the formulae (HetAr-1a) to (HetAr-1d) and most preferably from the formula (HetAr-1d), it being further preferable when Ar in the formulae (HetAr-1) to (HetAr-2) and (HetAr-1a) to (HetAr-1d) given represents an aromatic ring system which has 6 to 40 ring atoms and may be substituted by one or more R4 radicals, it being very preferable when Ar is a phenyl, biphenyl, terphenyl or a quaterphenyl, where the Ar groups mentioned may be substituted by one or more R4 radicals and R4 has the definition given above.
Preferred aromatic or heteroaromatic ring systems Ar are selected from phenyl, biphenyl, especially ortho-, meta- or para-biphenyl, terphenyl, especially ortho-, meta- or para-terphenyl or branched terphenyl, quaterphenyl, especially ortho-, meta- or para-quaterphenyl or branched quaterphenyl, fluorene which may be joined via the 1, 2, 3 or 4 position, spirobifluorene which may be joined via the 1, 2, 3 or 4 position, naphthalene, especially 1- or 2-bonded naphthalene, indole, benzofuran, benzothiophene, carbazole which may be joined via the 1, 2, 3 or 4 position, dibenzofuran which may be joined via the 1, 2, 3 or 4 position, dibenzothiophene which may be joined via the 1, 2, 3 or 4 position, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, quinoxaline, phenanthrene or triphenylene, each of which may be substituted by one or more R4 radicals.
The Ar groups here are more preferably independently selected from the groups of the following formulae Ar-1 to Ar-75:
where R4 is as defined above, the dotted bond represents the bond to HetAr and, in addition:
Preference is given to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16), (Ar-69), (Ar-70), (Ar-75), and particular preference to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16).
When the abovementioned groups for Ar have two or more A groups, possible options for these include all combinations from the definition of A. Preferred embodiments in that case are those in which one A group is NR4 and the other A group is C(R4)2 or in which both A groups are NR4 or in which both A groups are O.
When A is NR4, the substituent R4 bonded to the nitrogen atom is preferably an aromatic or heteroaromatic ring system which has 5 to 24 aromatic ring atoms and may also be substituted by one or more R5 radicals. In a particularly preferred embodiment, this R4 substituent is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, especially 6 to 18 aromatic ring atoms, which does not have any fused aryl groups and which does not have any fused heteroaryl groups in which two or more aromatic or heteroaromatic 6-membered ring groups are fused directly to one another, and which may also be substituted in each case by one or more R5 radicals. Preference is given to phenyl, biphenyl, terphenyl and quaterphenyl having bonding patterns as listed above for Ar-1 to Ar-11, where these structures, rather than by R4, may be substituted by one or more R5 radicals, but are preferably unsubstituted. Preference is further given to triazine, pyrimidine and quinazoline as listed above for Ar-47 to Ar-50, Ar-57 and Ar-58, where these structures, rather than by R4, may be substituted by one or more R5 radicals.
When A is C(R4)2, the substituents R4 bonded to this carbon atom are preferably the same or different at each instance and are a linear alkyl group having 1 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may also be substituted by one or more R5 radicals. Most preferably, R4 is a methyl group or a phenyl group. In this case, the R4 radicals together may also form a ring system, which leads to a spiro system.
There follows a description of preferred substituents R, R1, R2 and R3.
In a preferred embodiment of the invention, R, R2 and R3 are the same or different at each instance and are selected from the group consisting of H, D, F, CN, NO2, Si(R4)3, B(OR4)2, a straight-chain alkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl group may be substituted in each case by one or more R4 radicals, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R4 radicals.
In a further preferred embodiment of the invention, R, R2 and R3 are the same or different at each instance and are selected from the group consisting of H, D, F, a straight-chain alkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl group may be substituted in each case by one or more R4 radicals, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R4 radicals.
In a further preferred embodiment of the invention, R, R2 and R3 are the same or different at each instance and are selected from the group consisting of H, D, an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R4 radicals, and an N(Ar′)2 group. More preferably, R, R2 and R3 are the same or different at each instance and are selected from the group consisting of H or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, preferably 6 to 18 aromatic ring atoms, more preferably 6 to 13 aromatic ring atoms, and may be substituted in each case by one or more R4 radicals.
Preferred aromatic or heteroaromatic ring systems R, R2, R3 or Ar′ are selected from phenyl, biphenyl, especially ortho-, meta- or para-biphenyl, terphenyl, especially ortho-, meta- or para-terphenyl or branched terphenyl, quaterphenyl, especially ortho-, meta- or para-quaterphenyl or branched quaterphenyl, fluorene which may be joined via the 1, 2, 3 or 4 position, spirobifluorene which may be joined via the 1, 2, 3 or 4 position, naphthalene, especially 1- or 2-bonded naphthalene, indole, benzofuran, benzothiophene, carbazole which may be joined via the 1, 2, 3 or 4 position, dibenzofuran which may be joined via the 1, 2, 3 or 4 position, dibenzothiophene which may be joined via the 1, 2, 3 or 4 position, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, quinoxaline, phenanthrene or triphenylene, each of which may be substituted by one or more R4 radicals. The structures Ar-1 to Ar-75 listed above are particularly preferred, preference being given to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16), (Ar-69), (Ar-70), (Ar-75), and particular preference to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16).
Further suitable R, R2 and R3 groups are groups of the formula —Ar4—N(Ar2)(Ar3), where Ar2, Ar3 and Ar4 are the same or different at each instance and are an aromatic or heteroaromatic ring system which has 5 to 24 aromatic ring atoms and may be substituted in each case by one or more R4 radicals. The total number of aromatic ring atoms in Ar2, Ar3 and Ar4 here is not more than 60 and preferably not more than 40.
Ar4 and Ar2 here may also be bonded to one another and/or Ar2 and Ar3 to one another by a group selected from C(R4)2, NR4, O and S. Preferably, Ar4 and Ar2 are joined to one another and Ar2 and Ar3 to one another in the respective ortho position to the bond to the nitrogen atom. In a further embodiment of the invention, none of the Ar2, Ar3 and Ar4 groups are bonded to one another.
Preferably, Ar4 is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, preferably 6 to 12 aromatic ring atoms, and may be substituted in each case by one or more R4 radicals. More preferably, Ar4 is selected from the group consisting of ortho-, meta- or para-phenylene or ortho-, meta- or para-biphenyl, each of which may be substituted by one or more R4 radicals, but are preferably unsubstituted. Most preferably, Ar4 is an unsubstituted phenylene group.
Preferably, Ar2 and Ar3 are the same or different at each instance and are an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted in each case by one or more R4 radicals. Particularly preferred Ar2 and Ar3 groups are the same or different at each instance and are selected from the group consisting of benzene, ortho-, meta- or para-biphenyl, ortho-, meta- or para-terphenyl or branched terphenyl, ortho-, meta- or para-quaterphenyl or branched quaterphenyl, 1-, 2-, 3- or 4-fluorenyl, 1-, 2-, 3- or 4-spirobifluorenyl, 1- or 2-naphthyl, indole, benzofuran, benzothiophene, 1-, 2-, 3- or 4-carbazole, 1-, 2-, 3- or 4-dibenzofuran, 1-, 2-, 3- or 4-dibenzothiophene, indenocarbazole, indolocarbazole, 2-, 3- or 4-pyridine, 2-, 4- or 5-pyrimidine, pyrazine, pyridazine, triazine, phenanthrene or triphenylene, each of which may be substituted by one or more R1 radicals. Most preferably, Ar2 and Ar3 are the same or different at each instance and are selected from the group consisting of benzene, biphenyl, especially ortho-, meta- or para-biphenyl, terphenyl, especially ortho-, meta- or para-terphenyl or branched terphenyl, quaterphenyl, especially ortho-, meta- or para-quaterphenyl or branched quaterphenyl, fluorene, especially 1-, 2-, 3- or 4-fluorene, or spirobifluorene, especially 1-, 2-, 3- or 4-spirobifluorene.
In a preferred embodiment of the invention, R1 is the same or different at each instance and is selected from the group consisting of a straight-chain alkyl group having 1 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms, where the alkyl group may be substituted in each case by one or more R4 radicals, or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted in each case by one or more R4 radicals; at the same time, two R1 radicals together may also form a ring system. More preferably, R1 is the same or different at each instance and is selected from the group consisting of a straight-chain alkyl group having 1, 2, 3 or 4 carbon atoms or a branched or cyclic alkyl group having 3 to 6 carbon atoms, where the alkyl group may be substituted in each case by one or more R4 radicals, but is preferably unsubstituted, or an aromatic ring system which has 6 to 12 aromatic ring atoms, especially 6 aromatic ring atoms, and may be substituted in each case by one or more preferably nonaromatic R4 radicals, but is preferably unsubstituted; at the same time, two R1 radicals together may form a ring system. Most preferably, R1 is the same or different at each instance and is selected from the group consisting of a straight-chain alkyl group having 1, 2, 3 or 4 carbon atoms, or a branched alkyl group having 3 to 6 carbon atoms. Most preferably, R1 is a methyl group or is a phenyl group, where two phenyl groups together may form a ring system, preference being given to a methyl group over a phenyl group.
In a further preferred embodiment of the invention, R4 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, a straight-chain alkyl group having 1 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms, where the alkyl group may be substituted in each case by one or more R2 radicals, or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted in each case by one or more R5 radicals. In a particularly preferred embodiment of the invention, R4 is the same or different at each instance and is selected from the group consisting of H, a straight-chain alkyl group having 1 to 6 carbon atoms, especially having 1, 2, 3 or 4 carbon atoms, or a branched or cyclic alkyl group having 3 to 6 carbon atoms, where the alkyl group may be substituted by one or more R5 radicals, but is preferably unsubstituted, or an aromatic or heteroaromatic ring system which has 6 to 13 aromatic ring atoms and may be substituted in each case by one or more R5 radicals, but is preferably unsubstituted.
In a further preferred embodiment of the invention, R5 is the same or different at each instance and is H, an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms, which may be substituted by an alkyl group having 1 to 4 carbon atoms, but is preferably unsubstituted.
At the same time, in compounds of the invention that are processed by vacuum evaporation, the alkyl groups preferably have not more than five carbon atoms, more preferably not more than 4 carbon atoms, most preferably not more than 1 carbon atom. For compounds which are processed from solution, suitable compounds are also those substituted by alkyl groups, especially branched alkyl groups, having up to 10 carbon atoms or those substituted by oligoarylene groups, for example ortho-, meta- or para-terphenyl or branched terphenyl or quaterphenyl groups.
When the compounds of the formula (1) or the preferred embodiments are used as matrix material for a phosphorescent emitter or in a layer directly adjoining a phosphorescent layer, it is further preferable when the compound does not contain any fused aryl or heteroaryl groups in which more than two six-membered rings are fused directly to one another. An exception to this is formed by phenanthrene and triphenylene which, because of their high triplet energy, may be preferable in spite of the presence of fused aromatic six-membered rings.
The abovementioned preferred embodiments may be combined with one another as desired within the restrictions defined in claim 1. In a particularly preferred embodiment of the invention, the abovementioned preferences occur simultaneously.
Examples of preferred compounds according to the embodiments detailed above are the compounds detailed in the following table:
The base structure of the compounds of the invention can be prepared by the routes outlined in the schemes which follow. The individual synthesis steps, for example C—C coupling reactions according to Suzuki, C—N coupling reactions according to Hartwig-Buchwald or cyclization reactions, are known in principle to those skilled in the art. Further information relating to the synthesis of the compounds of the invention can be found in the synthesis examples. The synthesis of the base structure is shown in Scheme 1. This can be effected by coupling a benzofluorene substituted by a reactive leaving group, for example bromine, with an optionally substituted 2-nitrobenzeneboronic acid, followed by a ring closure reaction. Alternatively, the coupling can be effected with the amino group of an optionally substituted 2-aminochlorobenzene, followed by a ring closure reaction. Schemes 2 and 3 show various options for the introduction of the naphthylene-HetAr group on the nitrogen atom in the base skeleton. It is possible here to introduce a naphthylene-HetAr group substituted by a suitable leaving group, for example bromine, in a nucleophilic aromatic substitution or a palladium-catalysed coupling reaction as shown in Scheme 2. Alternatively, first of all, in a nucleophilic aromatic substitution, the naphthylene group that still bears a suitable leaving group, for example bromine, can be introduced in the base skeleton and, in a further coupling reaction, optionally after conversion to a boronic acid derivative, the HetAr group can be introduced, as shown in Scheme 3.
The definition of the symbols used in Schemes 1 to 3 corresponds essentially to that which was specified for formula (1), dispensing with numbering and complete representation of all symbols for reasons of clarity.
The present invention therefore further provides a process for preparing a compound of the invention, wherein the base skeleton that does not as yet contain the naphthylene-HetAr group is first synthesized, and wherein the naphthylene-HetAr group is introduced by means of a nucleophilic aromatic substitution reaction or a coupling reaction.
For the processing of the compounds of the invention from a liquid phase, for example by spin-coating or by printing methods, formulations of the compounds of the invention are required. These formulations may, for example, be solutions, dispersions or emulsions. For this purpose, it may be preferable to use mixtures of two or more solvents. Suitable and preferred solvents are, for example, toluene, anisole, o-, m- or p-xylene, methyl benzoate, mesitylene, tetralin, veratrole, THF, methyl-THF, THP, chlorobenzene, dioxane, phenoxytoluene, especially 3-phenoxytoluene, (−)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol, 2-pyrrolidinone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, acetophenone, α-terpineol, benzothiazole, butyl benzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene, decalin, dodecylbenzene, ethyl benzoate, indane, NMP, p-cymene, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethylene glycol butyl methyl ether, triethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane, 2-methylbiphenyl, 3-methylbiphenyl, 1-methylnaphthalene, 1-ethylnaphthalene, ethyl octanoate, diethyl sebacate, octyl octanoate, heptylbenzene, menthyl isovalerate, cyclohexyl hexanoate or mixtures of these solvents.
The present invention therefore further provides a formulation or a composition comprising at least one compound of the invention and at least one further compound. The further compound may, for example, be a solvent, especially one of the abovementioned solvents or a mixture of these solvents. If the further compound comprises a solvent, this mixture is referred to herein as formulation. The further compound may alternatively be at least one further organic or inorganic compound which is likewise used in the electronic device, for example an emitting compound and/or a further matrix material. Suitable emitting compounds and further matrix materials are listed at the back in connection with the organic electroluminescent device. The further compound may also be polymeric.
The present invention further provides for the use of a compound of the invention in an electronic device, especially in an organic electroluminescent device.
The present invention still further provides an electronic device comprising at least one compound of the invention. An electronic device in the context of the present invention is a device comprising at least one layer comprising at least one organic compound. This component may also comprise inorganic materials or else layers formed entirely from inorganic materials.
The electronic device is preferably selected from the group consisting of organic electroluminescent devices (OLEDs, sOLEDs, PLEDs, LECs, etc.), preferably organic light-emitting diodes (OLEDs), organic light-emitting diodes based on small molecules (sOLEDs), organic light-emitting diodes based on polymers (PLEDs), light-emitting electrochemical cells (LECs), organic laser diodes (O-laser), organic plasmon-emitting devices (D. M. Koller et al., Nature Photonics 2008, 1-4), organic integrated circuits (O-ICs), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic optical detectors, organic photoreceptors, organic field-quench devices (O-FQDs) and organic electrical sensors, preferably organic electroluminescent devices (OLEDs, sOLEDs, PLEDs, LECs, etc.), more preferably organic light-emitting diodes (OLEDs), organic light-emitting diodes based on small molecules (sOLEDs), organic light-emitting diodes based on polymers (PLEDs), especially phosphorescent OLEDs.
The organic electroluminescent device comprises cathode, anode and at least one emitting layer. Apart from these layers, it may also comprise further layers, for example in each case one or more hole injection layers, hole transport layers, hole blocker layers, electron transport layers, electron injection layers, exciton blocker layers, electron blocker layers and/or charge generation layers. It is likewise possible for interlayers having an exciton-blocking function, for example, to be introduced between two emitting layers. However, it should be pointed out that not necessarily every one of these layers need be present. In this case, it is possible for the organic electroluminescent device to contain an emitting layer, or for it to contain a plurality of emitting layers. If a plurality of emission layers are present, these preferably have several emission maxima between 380 nm and 750 nm overall, such that the overall result is white emission; in other words, various emitting compounds which may fluoresce or phosphoresce are used in the emitting layers. Especially preferred are systems having three emitting layers, where the three layers show blue, green and orange or red emission. The organic electroluminescent device of the invention may also be a tandem electroluminescent device, especially for white-emitting OLEDs.
It presents no difficulties at all to the person skilled in the art to consider a multitude of materials known in the prior art in order to select suitable materials for use in the additional layers of the organic electroluminescent device. The person skilled in the art here will reflect in a customary manner on the chemical and physical properties of the materials, since he knows that the materials interact with one another in an organic electroluminescent device. This relates, for example, to the energy levels of the orbitals (HOMO, LUMO) or else the triplet and singlet energy levels, but also other material properties.
Listed by way of example hereinafter are selected electron transport materials that are particularly suitable for use in the electron blocker or electron transport layer, either in combination with the compounds of the invention or else without the compounds of the invention as electron transport or electron blocker material in an electron blocker or electron transport layer. These are preferably triazines, very preferably 1,3,5-triazines, which may most preferably have aromatic and/or heteroaromatic substitution. Explicit examples of preferred electron transport materials with 1,3,5-triazine structure and the syntheses thereof are disclosed, for example, in WO2010/072300 A1, WO2014/023388 A1 and Prior Art Journal 2017 #03, 188-260. Some selected compounds are shown below.
The compound of the invention may be used in different layers, according to the exact structure. Preference is given to an organic electroluminescent device comprising a compound of formula (1) or the above-recited preferred embodiments in an emitting layer as matrix material for phosphorescent emitters or for emitters that exhibit TADF (thermally activated delayed fluorescence), especially for phosphorescent emitters. In addition, the compound of the invention can also be used in an electron transport layer and/or in a hole transport layer and/or in an exciton blocker layer and/or in a hole blocker layer. Particular preference is given to using the compound of the invention as matrix material for red-, orange- or yellow-phosphorescing emitters, especially for red-phosphorescing emitters, in an emitting layer or as electron transport material or hole blocker material in an electron transport layer or hole blocker layer.
When the compound of the invention is used as matrix material for a phosphorescent compound in an emitting layer, it is preferably used in combination with one or more phosphorescent materials (triplet emitters). Phosphorescence in the context of this invention is understood to mean luminescence from an excited state having higher spin multiplicity, i.e. a spin state >1, especially from an excited triplet state. In the context of this application, all luminescent complexes with transition metals or lanthanides, especially all iridium, platinum and copper complexes, shall be regarded as phosphorescent compounds.
The mixture of the compound of the invention and the emitting compound contains between 99% and 1% by volume, preferably between 98% and 10% by volume, more preferably between 97% and 60% by volume and especially between 95% and 80% by volume of the compound of the invention, based on the overall mixture of emitter and matrix material. Correspondingly, the mixture contains between 1% and 99% by volume, preferably between 2% and 90% by volume, more preferably between 3% and 40% by volume and especially between 5% and 20% by volume of the emitter, based on the overall mixture of emitter and matrix material.
In one embodiment of the invention, the compound of the invention is used here as the sole matrix material (“single host”) for the phosphorescent emitter.
A further embodiment of the present invention is the use of the compound of the invention as matrix material for a phosphorescent emitter in combination with a further matrix material. Suitable matrix materials which can be used in combination with the inventive compounds are aromatic ketones, aromatic phosphine oxides or aromatic sulfoxides or sulfones, for example according to WO 2004/013080, WO 2004/093207, WO 2006/005627 or WO 2010/006680, triarylamines, carbazole derivatives, e.g. CBP (N,N-biscarbazolylbiphenyl) or the carbazole derivatives disclosed in WO 2005/039246, US 2005/0069729, JP 2004/288381, EP 1205527, WO 2008/086851 or WO 2013/041176, indolocarbazole derivatives, for example according to WO 2007/063754 or WO 2008/056746, indenocarbazole derivatives, for example according to WO 2010/136109, WO 2011/000455, WO 2013/041176 or WO 2013/056776, azacarbazole derivatives, for example according to EP 1617710, EP 1617711, EP 1731584, JP 2005/347160, bipolar matrix materials, for example according to WO 2007/137725, silanes, for example according to WO 2005/111172, azaboroles or boronic esters, for example according to WO 2006/117052, triazine derivatives, for example according to WO 2007/063754, WO 2008/056746, WO 2010/015306, WO 2011/057706, WO 2011/060859 or WO 2011/060877, zinc complexes, for example according to EP 652273 or WO 2009/062578, diazasilole or tetraazasilole derivatives, for example according to WO 2010/054729, diazaphosphole derivatives, for example according to WO 2010/054730, bridged carbazole derivatives, for example according to WO 2011/042107, WO 2011/060867, WO 2011/088877 and WO 2012/143080, triphenylene derivatives, for example according to WO 2012/048781, dibenzofuran derivatives, for example according to WO 2015/169412, WO 2016/015810, WO 2016/023608, WO 2017/148564 or WO 2017/148565, or biscarbazoles, for example according to JP 3139321 B2.
It is likewise possible for a further phosphorescent emitter which emits at a shorter wavelength than the actual emitter to be present as co-host in the mixture. Particularly good results are achieved when the emitter used is a red-phosphorescing emitter and the co-host used in combination with the compound of the invention is a yellow-phosphorescing emitter.
In addition, the co-host used may be a compound that does not take part in charge transport to a significant degree, if at all, as described, for example, in WO 2010/108579. Especially suitable in combination with the compound of the invention as co-matrix material are compounds which have a large bandgap and themselves take part at least not to a significant degree, if any at all, in the charge transport of the emitting layer. Such materials are preferably pure hydrocarbons. Examples of such materials can be found, for example, in WO 2009/124627 or in WO 2010/006680.
Particularly preferred co-host materials which can be used in combination with the compounds of the invention are compounds of one of the formulae (6), (7), (8), (9) and (10), preferably biscarbazole derivatives of one of the formulae (6), (7), (8), (9) and (10),
where the symbols and indices used are as follows:
The sum total of the indices s, t and u in compounds of the formulae (6), (7), (8), (9) and (10) is preferably not more than 6, especially preferably not more than 4 and more preferably not more than 2.
In a preferred embodiment of the invention, R6 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, NO2, Si(R7)3, B(OR7)2, a straight-chain alkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl group may be substituted in each case by one or more R7 radicals, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R7 radicals.
In a further preferred embodiment of the invention, R6 is the same or different at each instance and is selected from the group consisting of H, D, F, a straight-chain alkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl group may be substituted in each case by one or more R7 radicals, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R7 radicals.
In a further preferred embodiment of the invention, R6 is the same or different at each instance and is selected from the group consisting of H, D, an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R7 radicals, and an N(Ar″)2 group. More preferably, R6 is the same or different at each instance and is selected from the group consisting of H or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, preferably 6 to 18 aromatic ring atoms, more preferably 6 to 13 aromatic ring atoms, and may be substituted in each case by one or more R7 radicals.
Preferred aromatic or heteroaromatic ring systems R6 or Ar″ are selected from phenyl, biphenyl, especially ortho-, meta- or para-biphenyl, terphenyl, especially ortho-, meta- or para-terphenyl or branched terphenyl, quaterphenyl, especially ortho-, meta- or para-quaterphenyl or branched quaterphenyl, fluorene which may be joined via the 1, 2, 3 or 4 position, spirobifluorene which may be joined via the 1, 2, 3 or 4 position, naphthalene, especially 1- or 2-bonded naphthalene, indole, benzofuran, benzothiophene, carbazole which may be joined via the 1, 2, 3 or 4 position, dibenzofuran which may be joined via the 1, 2, 3 or 4 position, dibenzothiophene which may be joined via the 1, 2, 3 or 4 position, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, quinoxaline, phenanthrene or triphenylene, each of which may be substituted by one or more R7 radicals. The structures Ar-1 to Ar-75 listed above are particularly preferred, preference being given to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16), (Ar-69), (Ar-70), (Ar-75), and particular preference to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16). In the structures Ar-1 to Ar-75 set out above, in relation to the R6 and Ar″ radicals, the substituents R4 should be replaced by the corresponding R7 radicals. The preferences set out above for the R2 and R3 groups are correspondingly applicable to the R6 group.
Further suitable R6 groups are groups of the formula —Ar4—N(Ar2)(Ar3), where Ar2, Ar3 and Ar4 are the same or different at each instance and are an aromatic or heteroaromatic ring system which has 5 to 24 aromatic ring atoms and may be substituted in each case by one or more R4 radicals. The total number of aromatic ring atoms in Ar2, Ar3 and Ar4 here is not more than 60 and preferably not more than 40. Further preferences for the Ar2, Ar3 and Ar4 groups have been set out above and are correspondingly applicable.
It may further be the case that the substituents R6 according to the above formulae do not form a fused aromatic or heteroaromatic ring system, preferably any fused ring system, with the ring atoms of the ring system. This includes the formation of a fused ring system with possible substituents R7, R8 which may be bonded to the R6 radicals.
When A1 is NR7, the substituent R7 bonded to the nitrogen atom is preferably an aromatic or heteroaromatic ring system which has 5 to 24 aromatic ring atoms and may also be substituted by one or more R8 radicals. In a particularly preferred embodiment, this R7 substituent is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, especially 6 to 18 aromatic ring atoms, which does not have any fused aryl groups and which does not have any fused heteroaryl groups in which two or more aromatic or heteroaromatic 6-membered ring groups are fused directly to one another, and which may also be substituted in each case by one or more R8 radicals. Preference is given to phenyl, biphenyl, terphenyl and quaterphenyl having bonding patterns as listed above for Ar-1 to Ar-11, where these structures, rather than by R4, may be substituted by one or more R8 radicals, but are preferably unsubstituted. Preference is further given to triazine, pyrimidine and quinazoline as listed above for Ar-47 to Ar-50, Ar-57 and Ar-58, where these structures, rather than by R4, may be substituted by one or more R8 radicals.
When A1 is C(R7)2, the substituents R7 bonded to this carbon atom are preferably the same or different at each instance and are a linear alkyl group having 1 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may also be substituted by one or more R8 radicals. Most preferably, R7 is a methyl group or a phenyl group. In this case, the R7 radicals together may also form a ring system, which leads to a spiro system.
Preferred aromatic or heteroaromatic ring systems Ar5 are selected from phenyl, biphenyl, especially ortho-, meta- or para-biphenyl, terphenyl, especially ortho-, meta- or para-terphenyl or branched terphenyl, quaterphenyl, especially ortho-, meta- or para-quaterphenyl or branched quaterphenyl, fluorene which may be joined via the 1, 2, 3 or 4 position, spirobifluorene which may be joined via the 1, 2, 3 or 4 position, naphthalene, especially 1- or 2-bonded naphthalene, indole, benzofuran, benzothiophene, carbazole which may be joined via the 1, 2, 3 or 4 position, dibenzofuran which may be joined via the 1, 2, 3 or 4 position, dibenzothiophene which may be joined via the 1, 2, 3 or 4 position, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, quinoxaline, phenanthrene or triphenylene, each of which may be substituted by one or more R7 radicals.
The Ar5 groups here are more preferably independently selected from the groups of the formulae Ar-1 to Ar-75 set out above, preference being given to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16), (Ar-69), (Ar-70), (Ar-75), and particular preference to structures of the formulae (Ar-1), (Ar-2), (Ar-3), (Ar-12), (Ar-13), (Ar-14), (Ar-15), (Ar-16). In the structures Ar-1 to Ar-75 set out above, in relation to the Ar5 radicals, the substituents R4 should be replaced by the corresponding R7 radicals.
In a further preferred embodiment of the invention, R7 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, a straight-chain alkyl group having 1 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms, where the alkyl group may be substituted in each case by one or more R2 radicals, or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted in each case by one or more R8 radicals. In a particularly preferred embodiment of the invention, R7 is the same or different at each instance and is selected from the group consisting of H, a straight-chain alkyl group having 1 to 6 carbon atoms, especially having 1, 2, 3 or 4 carbon atoms, or a branched or cyclic alkyl group having 3 to 6 carbon atoms, where the alkyl group may be substituted by one or more R5 radicals, but is preferably unsubstituted, or an aromatic or heteroaromatic ring system which has 6 to 13 aromatic ring atoms and may be substituted in each case by one or more R8 radicals, but is preferably unsubstituted.
In a further preferred embodiment of the invention, R8 is the same or different at each instance and is H, an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms, which may be substituted by an alkyl group having 1 to 4 carbon atoms, but is preferably unsubstituted.
Preferred embodiments of the compounds of the formulae (6) and (7) are the compounds of the following formulae (6a) and (7a):
where R6, Ar5 and A1 have the definitions given above, especially for formula (6) or (7). In a preferred embodiment of the invention, A1 in formula (7a) is C(R7)2.
Preferred embodiments of the compounds of the formulae (6a) and (7a) are the compounds of the following formulae (6b) and (7b):
where R6, Ar5 and A1 have the definitions given above, especially for formula (6) or (7). In a preferred embodiment of the invention, A1 in formula (7b) is C(R7)2.
Examples of suitable compounds of formulae (6), (7), (8), (9) and (10) are the compounds depicted below:
The combination of at least one compound of formula (1) or the preferred embodiments thereof that are set out above with a compound of one of the formulae (6), (7), (8), (9) and (10) can achieve surprising advantages. The present invention therefore further provides a composition comprising at least one compound of formula (1) or the preferred embodiments thereof that are set out above and at least one further matrix material, wherein the further matrix material is selected from compounds of one of the formulae (6), (7), (8), (9) and (10).
It may preferably be the case that the composition consists of at least one compound of formula (1) or the preferred embodiments thereof that are set out above and at least one compound of one of the formulae (6), (7), (8), (9) and (10). These compositions are especially suitable as what are called pre-mixtures, which can be evaporated together.
The compound of formula (1) or the preferred embodiments thereof that are set out above preferably has a proportion by mass in the composition in the range from 10% by weight to 95% by weight, more preferably in the range from 15% by weight to 90% by weight, and very preferably in the range from 40% by weight to 70% by weight, based on the total mass of the composition.
It may further be the case that the compounds of one of the formulae (6), (7), (8), (9) and (10) have a proportion by mass in the composition in the range from 5% by weight to 90% by weight, preferably in the range from 10% by weight to 85% by weight, more preferably in the range from 20% by weight to 85% by weight, even more preferably in the range from 30% by weight to 80% by weight, very particularly preferably in the range from 20% by weight to 60% by weight and most preferably in the range from 30% by weight to 50% by weight, based on the overall composition.
It may additionally be the case that the further matrix material is a hole-transporting matrix material of at least one of the formulae (6), (7), (8), (9) and (10), and the hole-transporting matrix material has a proportion by mass in the range from 10% by weight to 95% by weight, preferably in the range from 15% by weight to 90% by weight, more preferably in the range from 15% by weight to 80% by weight, even more preferably in the range from 20% by weight to 70% by weight, very particularly preferably in the range from 40% by weight to 80% by weight and most preferably in the range from 50% by weight to 70% by weight, based on the overall composition.
It may additionally be the case that the composition consists exclusively of the formula (1) or the preferred embodiments thereof that are set out above and one of the further matrix materials mentioned, preferably compounds of at least one of the formulae (6), (7), (8), (9) and (10).
Suitable phosphorescent compounds (=triplet emitters) are especially compounds which, when suitably excited, emit light, preferably in the visible region, and also contain at least one atom of atomic number greater than 20, preferably greater than 38 and less than 84, more preferably greater than 56 and less than 80, especially a metal having this atomic number. Preferred phosphorescence emitters used are compounds containing copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, especially compounds containing iridium or platinum.
Examples of the above-described emitters can be found in applications WO 00/70655, WO 2001/41512, WO 2002/02714, WO 2002/15645, EP 1191613, EP 1191612, EP 1191614, WO 05/033244, WO 05/019373, US 2005/0258742, WO 2009/146770, WO 2010/015307, WO 2010/031485, WO 2010/054731, WO 2010/054728, WO 2010/086089, WO 2010/099852, WO 2010/102709, WO 2011/032626, WO 2011/066898, WO 2011/157339, WO 2012/007086, WO 2014/008982, WO 2014/023377, WO 2014/094961, WO 2014/094960, WO 2015/036074, WO 2015/104045, WO 2015/117718, WO 2016/015815, WO 2016/124304, WO 2017/032439 and WO 2018/011186. In general, all phosphorescent complexes as used for phosphorescent electroluminescent devices according to the prior art and as known to those skilled in the art in the field of organic electroluminescence are suitable, and the person skilled in the art will be able to use further phosphorescent complexes without exercising inventive skill.
Examples of phosphorescent dopants are listed in the following table:
The compounds of the invention are especially also suitable as matrix materials for phosphorescent emitters in organic electroluminescent devices, as described, for example, in WO 98/24271, US 2011/0248247 and US 2012/0223633. In these multicolour display components, an additional blue emission layer is applied by vapour deposition over the full area to all pixels, including those having a colour other than blue.
In a further embodiment of the invention, the organic electroluminescent device of the invention does not contain any separate hole injection layer and/or hole transport layer and/or hole blocker layer and/or electron transport layer, meaning that the emitting layer directly adjoins the hole injection layer or the anode, and/or the emitting layer directly adjoins the electron transport layer or the electron injection layer or the cathode, as described, for example, in WO 2005/053051. It is additionally possible to use a metal complex identical or similar to the metal complex in the emitting layer as hole transport or hole injection material directly adjoining the emitting layer, as described, for example, in WO 2009/030981.
In the further layers of the organic electroluminescent device of the invention, it is possible to use any materials as typically used according to the prior art. The person skilled in the art will therefore be able, without exercising inventive skill, to use any materials known for organic electroluminescent devices in combination with the inventive compounds of formula (1) or the above-recited preferred embodiments.
Additionally preferred is an organic electroluminescent device, characterized in that one or more layers are coated by a sublimation process. In this case, the materials are applied by vapour deposition in vacuum sublimation systems at an initial pressure of less than 10−5 mbar, preferably less than 10−6 mbar. However, it is also possible that the initial pressure is even lower, for example less than 10−7 mbar.
Preference is likewise given to an organic electroluminescent device, characterized in that one or more layers are coated by the OVPD (organic vapour phase deposition) method or with the aid of a carrier gas sublimation. In this case, the materials are applied at a pressure between 10−5 mbar and 1 bar. A special case of this method is the OVJP (organic vapour jet printing) method, in which the materials are applied directly by a nozzle and thus structured.
Preference is additionally given to an organic electroluminescent device, characterized in that one or more layers are produced from solution, for example by spin-coating, or by any printing method, for example screen printing, flexographic printing, offset printing, LITI (light-induced thermal imaging, thermal transfer printing), inkjet printing or nozzle printing. For this purpose, soluble compounds are needed, which are obtained, for example, through suitable substitution.
Formulations for application of a compound of formula (1) or the preferred embodiments thereof that are set out above are novel. The present invention therefore further provides a formulation comprising at least one solvent and a compound of formula (1) or the preferred embodiments thereof that are set out above. Further provided is a formulation comprising at least one solvent and a compound of formula (1) or the preferred embodiments thereof that are set out above, and a compound of at least one of the formulae (6), (7), (8), (9) and (10).
In addition, hybrid methods are possible, in which, for example, one or more layers are applied from solution and one or more further layers are applied by vapour deposition.
These methods are known in general terms to those skilled in the art and can be applied by those skilled in the art without exercising inventive skill to organic electroluminescent devices comprising the compounds of the invention.
The compounds of the invention and the organic electroluminescent devices of the invention have the particular feature of an improved lifetime over the prior art. This is particularly true compared to similar compounds that have an indenocarbazole base skeleton rather than the benzindenocarbazole base skeleton. At the same time, the further electronic properties of the electroluminescent devices, such as efficiency or operating voltage, remain at least equally good. In a further variant, the compounds of the invention and the organic electroluminescent devices of the invention especially feature improved efficiency and/or operating voltage and higher lifetime compared to the prior art. This is particularly true compared to similar compounds that have an indenocarbazole base skeleton rather than the benzindenocarbazole base skeleton.
The electronic devices of the invention, especially organic electroluminescent devices, are notable for one or more of the following surprising advantages over the prior art:
These abovementioned advantages are not accompanied by an inordinately high deterioration in the further electronic properties.
It should be pointed out that variations of the embodiments described in the present invention are covered by the scope of this invention. Any feature disclosed in the present invention may, unless this is explicitly ruled out, be exchanged for alternative features which serve the same purpose or an equivalent or similar purpose. Thus, any feature disclosed in the present invention, unless stated otherwise, should be considered as an example of a generic series or as an equivalent or similar feature.
All features of the present invention may be combined with one another in any manner, unless particular features and/or steps are mutually exclusive. This is especially true of preferred features of the present invention. Equally, features of non-essential combinations may be used separately (and not in combination).
It should also be pointed out that many of the features, and especially those of the preferred embodiments of the present invention, should themselves be regarded as inventive and not merely as some of the embodiments of the present invention. For these features, independent protection may be sought in addition to or as an alternative to any currently claimed invention.
The technical teaching disclosed with the present invention may be abstracted and combined with other examples.
The invention is illustrated in more detail by the examples which follow, without any intention of restricting it thereby. The person skilled in the art will be able to use the information given to execute the invention over the entire scope disclosed and to prepare further compounds of the invention without exercising inventive skill and to use them in electronic devices or to employ the process of the invention.
The syntheses which follow, unless stated otherwise, are conducted under a protective gas atmosphere in dried solvents. The solvents and reagents can be purchased from ALDRICH or ABCR. The numbers given for the reactants are the corresponding CAS numbers.
47 g (145 mmol) of 9-bromo-11,11-dimethyl-11H-benzo[a]fluorene, 16.8 g (159 mmol) of 2-chloroaniline, 41.9 g (436.2 mmol) of sodium tert-butoxide, 1.06 g (1.45 mmol) of Pd(dppf)Cl2 are dissolved in 500 ml of toluene and stirred under reflux for 5 h. The reaction mixture is cooled down to room temperature, extended with toluene and filtered through Celite. The filtrate is concentrated under reduced pressure and the residue is crystallized from toluene/heptane. The product is isolated as a colourless solid. Yield: 33 g (89 mmol), 70% of theory.
The following compounds can be prepared in an analogous manner:
b) Cyclization
48 g (129 mmol) of (2-chlorophenyl)(11,11-dimethyl-11H-benzo[a]fluoren-9-yl)amine, 53 g (389 mmol) of potassium carbonate, 4.5 g (12 mmol) of tricyclohexylphosphine tetrafluoroborate, 1.38 g (6 mmol) of palladium(II) acetate and 3.3 g (32 mmol) of pivalic acid are suspended in 500 ml of dimethylacetamide and stirred under reflux for 6 h. After cooling, the reaction mixture is admixed with 300 ml of water and 400 ml of CH2Cl2. The mixture is stirred for a further 30 min, the organic phase is separated off and filtered through a short Celite bed, and then the solvent is removed under reduced pressure. The crude product is subjected to hot extraction with toluene and recrystallized from toluene. The product is isolated as a beige solid. Yield: 34 g (102 mmol), 78% of theory.
The following compounds can be prepared in an analogous manner:
To a well-stirred, degassed suspension of 59 g (183.8 mmol) of 2-nitrobenzeneboronic acid, 54 g (184 mmol) of 3-bromo-11,11-dimethyl-11H-benzo[b]fluorene and 66.5 g (212.7 mmol) of potassium carbonate in a mixture of 250 ml of water and 250 ml of THE are added 1.7 g (1.49 mmol) of Pd(PPh3)4, and the mixture is heated under reflux for 17 h. After cooling, the organic phase is separated off, washed three times with 200 ml each time of water and once with 200 ml of saturated aqueous sodium chloride solution, dried over magnesium sulfate and concentrated to dryness by rotary evaporation. The grey residue is recrystallized from hexane. The precipitated crystals are filtered off with suction, washed with a little MeOH and dried under reduced pressure. Yield: 53 g (146 mmol); 80% of theory.
The following compounds can be prepared in an analogous manner:
d) Carbazole Synthesis
A mixture of 87 g (240 mmol) of 11,11-dimethyl-3-(2-nitrophenyl)-11H-benzo[b]fluorene and 290.3 ml (1669 mmol) of triethyl phosphite is heated under reflux for 12 h. Subsequently, the rest of the triethyl phosphite is distilled off (72-76° C./9 mm Hg). Water/MeOH (1:1) is added to the residue, and the solids are filtered off and recrystallized. Yield: 58 g (176 mmol); 74% of theory.
The following compounds can be prepared in an analogous manner:
e) Nucleophilic Substitution
4.2 g of NaH, 60% in mineral oil, (106 mmol) is dissolved in 300 ml of dimethylformamide under a protective atmosphere. 34 g (106 mmol) of 7,9-dihydro-7,7-dimethylbenz[6,7]indeno[2,1-b]carbazole is dissolved in 250 ml of DMF and added dropwise to the reaction mixture. After 1 hour at room temperature, a solution of 2-(4-bromo-1-naphthalenyl)-4,6-diphenyl[1,3,5]triazine (48 g, 122 mmol) in 200 ml of THE is added dropwise. The reaction mixture is then stirred at room temperature for 12 h. After this time, the reaction mixture is poured onto ice. After warming to room temperature, the solids that precipitate out are filtered and washed with ethanol and heptane. The residue is subjected to hot extraction with toluene and recrystallized from toluene/n-heptane and finally sublimed under high vacuum; purity is 99.9%. The yield is 50 g (72 mmol); 68% of theory.
The following compounds can be prepared in an analogous manner:
f) Bromination
158 g (230 mmol) of compound e is initially charged in 1000 ml of THF. Subsequently, a solution of 41.7 g (234.6 mmol) of NBS in 500 ml of THE is added dropwise in the dark at −15° C., the mixture is allowed to come to RT and stirring is continued at this temperature for 4 h. Subsequently, 150 ml of water are added to the mixture and extraction is effected with CH2Cl2. The organic phase is dried over MgSO4 and the solvents are removed under reduced pressure. The product is subjected to extractive stirring with hot hexane and filtered off with suction. Yield: 104 g (135 mmol), 59% of theory, purity by 1H NMR about 98%.
The following compounds can be prepared in an analogous manner:
g) Suzuki Reaction
33.5 g (44 mmol) of the product from Example f, 13.4 g (47 mmol) of 9-phenylcarbazole-3-boronic acid and 29.2 g of Rb2CO3 are suspended in 250 ml of p-xylene. To this suspension are added 0.95 g (4.2 mmol) of Pd(OAc)2 and 12.6 ml of a 1M tri-tert-butylphosphine solution. The reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, washed three times with 200 ml of water and then concentrated to dryness. The residue is subjected to hot extraction with toluene, recrystallized from toluene and finally sublimed under high vacuum; the purity is 99.9%. Yield: 28 g (30 mmol), 70% of theory.
The following compounds can be prepared in an analogous manner:
Production of the Electroluminescent Devices
Examples C1 to I9 which follow (see table 1) present the use of the materials of the invention in electroluminescent devices.
Pretreatment for examples C1-I9: Glass plaques coated with structured ITO (indium tin oxide) of thickness 50 nm are treated prior to coating, first with an oxygen plasma, followed by an argon plasma. These plasma-treated glass plaques form the substrates to which the electroluminescent devices are applied.
The electroluminescent devices basically have the following layer structure: substrate/hole injection layer (HIL)/hole transport layer (HTL)/electron blocker layer (EBL)/emission layer (EML)/optional hole blocker layer (HBL)/electron transport layer (ETL)/optional electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer of thickness 100 nm. The exact structure of the OLEDs can be found in table 1. The materials required for production of the electroluminescent devices are shown in table 2. The data of the electroluminescent devices are listed in table 3.
All materials are applied by thermal vapour deposition in a vacuum chamber. In this case, the emission layer always consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as 1e:IC2:TER5 (57%:40%:3%) mean here that the material 1e is present in the layer in a proportion by volume of 57%, IC2 in a proportion of 40% and TER5 in a proportion of 3%. Analogously, the electron transport layer may also consist of a mixture of two materials.
The electroluminescent devices are characterized in a standard manner. For this purpose, the electroluminescence spectra, the current efficiency (CE, measured in cd/A) and the external quantum efficiency (EQE, measured in %) are determined as a function of luminance, calculated from current-voltage-luminance characteristics assuming Lambertian emission characteristics, as is the lifetime. The electroluminescence spectra are determined at a luminance of 1000 cd/m2, and the CIE 1931 x and y colour coordinates are calculated therefrom. The parameter U1000 in table 3 refers to the voltage which is required for a luminance of 1000 cd/m2. CE1000 and EQE1000 respectively denote the current efficiency and external quantum efficiency that are attained at 1000 cd/m2.
The lifetime LT is defined as the time after which the luminance drops from the starting luminance to a certain proportion L1 in the course of operation with constant current density j0. A figure of L1=95% in table 3 means that the lifetime reported in the LT column corresponds to the time after which the luminance falls to 95% of its starting value.
Use of Mixtures of the Invention in the Emission Layer of Phosphorescent Electroluminescent Devices
The materials of the invention are used in examples I1 to I9 as matrix material in the emission layer of red-phosphorescing electroluminescent devices. By comparison with the prior art (C1 to C5), it is possible to achieve a distinct improvement in lifetime with otherwise comparable parameters.
The data set out above show that compounds having all the features of Claim 1 lead to unexpected improvements. Compounds having a naphthyl group that functions as connecting group between the nitrogen atom of a benzoindenocarbazole radical and an electron-deficient heteroaryl group have a surprisingly longer lifetime than compounds that have the same electron-deficient heteroaryl groups but do not have a naphthyl group, but rather a phenyl group, as connecting group (cf. comparative experiments C2 and C3 with inventive experiments I1, I2 and I5), or than compounds having the same electron-deficient heteroaryl groups, in which the benzo radical is fused not to the indene group but to the carbazole group, or having no benzo group fused to the indeno group (cf. comparative experiments C1, C4 and C5 with inventive experiments I1, I2, I3 and I5).
In addition, the data show that compounds in which the group of the formula (2) has been fused on according to compounds of formula (3) have surprising advantages. Accordingly, preference is given to compounds of formula (3).
In addition, compounds in which the HetAr group forms a ring closure together with the naphthylene group show high performance, as demonstrated by example I3.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19195144.1 | Sep 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/074320 | 9/1/2020 | WO |
