Patent Application
20230292596
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 (OLEDs) are frequently phosphorescent organometallic complexes. In general terms, there is still a need for improvement in OLEDs, especially also in OLEDs which exhibit triplet emission (phosphorescence), for example with regard to efficiency, operating voltage and lifetime. The properties of phosphorescent OLEDs 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 to these materials can thus also lead to improvements in the OLED properties. Suitable matrix materials for OLEDs are, for example, aromatic lactams as disclosed, for example, in WO 2011/116865, WO 2011/137951, WO 2013/064206 or KR 2015-037703.
It is an object of the present invention to provide compounds which are suitable for use in an OLED, especially as matrix material for phosphorescent emitters or as electron transport material, and which lead to improved properties therein.
It has been found that, surprisingly, this object is achieved by particular compounds described in detail hereinafter that are of good suitability for use in OLEDs. These OLEDs especially have a long lifetime, high efficiency and relatively low operating voltage. The present invention therefore provides these compounds and electronic devices, especially organic electroluminescent devices, comprising these compounds.
The present invention provides a compound of formula (1)
where the symbols 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. An aryl group or heteroaryl group is understood here to mean either a simple aromatic cycle, i.e. benzene, or a simple heteroaromatic cycle, for example pyridine, pyrimidine, thiophene, etc., or a fused (annelated) aryl or heteroaryl group, for example naphthalene, anthracene, phenanthrene, quinoline, isoquinoline, etc. Aromatics 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 aromatic ring system in the context of this invention contains 6 to 60 carbon atoms, preferably 6 to 40 carbon atoms, in the ring system. A heteroaromatic ring system in the context of this invention contains 2 to 60 carbon atoms, preferably 2 to 40 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 non-aromatic unit, for example a carbon, nitrogen or oxygen atom. These shall likewise be understood to mean systems in which two or more aryl or heteroaryl groups are joined directly to one another, for example biphenyl, terphenyl, bipyridine or phenylpyridine. 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. Preferred aromatic or heteroaromatic ring systems are simple aryl or heteroaryl groups and groups in which two or more aryl or heteroaryl groups are joined directly to one another, for example biphenyl or bipyridine, and also fluorene or spirobifluorene.
An electron-rich heteroaromatic ring system is characterized in that it is a heteroaromatic ring system containing no electron-deficient heteroaryl groups. An electron-deficient heteroaryl group is a six-membered heteroaryl group having at least one having at least one nitrogen atom or a five-membered heteroaryl group having at least two heteroatoms, one of which is a nitrogen atom and the other is oxygen, sulfur or a substituted nitrogen atom, where further aryl or heteroaryl groups may also be fused onto these groups in each case. By contrast, electron-rich heteroaryl groups our five-membered heteroaryl groups having exactly one heteroatom selected from oxygen, sulfur and substituted nitrogen, to which may be fused further aryl groups and/or further electron-rich five-membered heteroaryl groups. Thus, examples of electron-rich heteroaryl groups are pyrrole, furan, thiophene, indole, benzofuran, benzothiophene, carbazole, dibenzofuran, dibenzothiophene or indenocarbazole. An electron-rich heteroaryl group is also referred to as an electron-rich heteroaromatic radical.
According to the invention, in the case of an electron-rich heteroaromatic ring system R, the bond of the electron-rich heteroaryl group to the base skeleton is via a carbon atom. When the electron-rich heteroaromatic ring system is a carbazole group, for example, this is bonded to the base skeleton of the compound of the formula (1) via a carbon atom and not via the nitrogen atom. By contrast, a linkage of the carbazole group to the base skeleton via the nitrogen atom of the carbazole group is not in accordance with the invention. The same is true, for example, when R is an N-phenylcarbazole group. In this case, a compound in which the N-phenylcarbazole group is bonded to the base skeleton via the phenyl group is not encompassed by the invention because, in this case, the electron-rich heteroaryl group, i.e. the carbazole group, would be bonded to the base skeleton via the nitrogen atom (via the phenylene linker). In a preferred embodiment of the invention, the R radical does not contain a carbazole group.
An electron-deficient heteroaromatic ring system is characterized in that it contains at least one electron-deficient heteroaryl group and preferably no electron-rich heteroaryl groups.
In the context of the present invention, the term “alkyl group” is used as an umbrella term both for linear and branched alkyl groups and for cyclic alkyl groups. Analogously, the terms “alkenyl group” and “alkynyl group” are used as umbrella terms both for linear or branched alkenyl or alkynyl groups and for cyclic alkenyl or alkynyl groups.
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 40 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 OR1 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 SR1 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, more preferably F or CN.
An aromatic or heteroaromatic ring system which has 5-60 aromatic ring atoms and may also be substituted in each case by the abovementioned R2 radicals or a hydrocarbyl radical 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 a combination of these systems.
The wording that two or more radicals together may form a ring system, 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 shall 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 will be illustrated by the following scheme:
Further preferred embodiments are shown by the following formulae (2) and (3):
where the symbols used have the definitions given above and the aromatic systems may be substituted identically or differently by one or more R groups as shown.
In a preferred embodiment of the invention, in at least one of the lateral aromatic six-membered rings of the compound of the formula (1), identically or differently, in up to two instances in each case, an X group is CR where R is 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 R1 radicals.
In a preferred embodiment of the invention, not more than two symbols X per cycle are N, more preferably not more than one symbol X.
In a preferred embodiment of the invention, X is CR.
In a preferred embodiment, in the case of two adjacent X with X═CR, the R radicals are not bonded to one another via at least one covalent bond; preferably, no R radical in the case of X═CR is bonded to another R radical via at least one covalent bond. More preferably, two or more R radicals in the case of X═CR do not form a ring. This is preferably also true of all other R1 and R2 radicals in these R radicals.
Further preferred embodiments are shown by the following formulae (4) and (5):
where the symbols used have the definitions given above and the aromatic systems may be substituted identically or differently by one or more R groups are shown.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (4) and (5) are not H or D, preferably not more than 2 R groups.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (4) and (5) are not H or D, preferably not more than 2 R groups, in which case R is then 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 R1 radicals.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (4) and (5) are not H or D, preferably not more than 2 R groups, in which case R is then an aromatic or an electron-deficient 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 R1 radicals.
In a further preferred embodiment of the compounds detailed above and hereinafter, Y is CR2, O or S.
In a further preferred embodiment of the invention, the compound is selected from compounds of the formulae (6) to (8):
where the symbols used have the definitions given above.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (6) to (8) are not H or D, preferably not more than 2 R groups, in which case R is then 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 R1 radicals.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (6) to (8) are not H or D, preferably not more than 2 R groups, in which case R is then an aromatic or electron-deficient 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 R1 radicals.
In a further preferred embodiment of the invention, the compound is selected from compounds of the formulae (9) to (16):
where the symbols used have the definitions given above.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (9) to (16) are not H or D, preferably not more than 2 R groups, in which case R is an aromatic 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 R1 radicals.
In a preferred embodiment of the invention, not more than 3 R groups in the formulae (9) to (16) are not H or D, preferably not more than 2 R groups, in which case R is an aromatic or electron-deficient 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 R1 radicals.
There follows a description of preferred substituents R, Ar, R1 and R2. In a particularly preferred embodiment of the invention, the preferences specified hereinafter for R, Ar, R1 and R2 occur simultaneously and are applicable to the structures of the formula (1) and to all preferred embodiments detailed above.
In a preferred embodiment, Ar is an aromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R radicals, or a heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R radicals. In a particularly preferred embodiment of the invention, Ar is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, even more preferably 6 to 13 aromatic ring atoms, and may be substituted by one or more, preferably nonaromatic, R radicals.
Suitable aromatic or heteroaromatic ring systems Ar are the same or different at each instance and 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 which may be joined via the 1 or 2 position, indole, benzofuran, benzothiophene, 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, phenanthrene, triphenylene or a combination of two or three of these groups, each of which may be substituted by one or more R radicals, preferably nonaromatic R radicals.
Further preferred embodiments of Ar, when these represent a heteroaromatic ring system, are selected from the group consisting of pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinoline, quinazoline, quinoxaline and benzimidazole or a combination of these groups with one of the abovementioned groups, each of which may be substituted by one or more R radicals. When Ar is a heteroaryl group, especially triazine, pyrimidine, quinazoline or quinoxaline, preference may also be given to aromatic or heteroaromatic R radicals on this heteroaryl group.
In a preferred embodiment of the invention, R is the same or different at each instance and is selected from the group consisting of H, D, F, CN, OR1, a straight-chain alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms, where the alkyl or alkenyl group may each be substituted by one or more R1 radicals, but is preferably unsubstituted, and where one or more nonadjacent CH2 groups may be replaced by O, or an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted in each case by one or more R1 radicals; at the same time, two R radicals together may also form an aliphatic ring system or else, when they are bonded to the same carbon atom, an aromatic or heteroaromatic ring system. More preferably, R 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 in each case may be substituted by one or more R1 radicals, but is preferably unsubstituted, or an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, especially 6 to 13 aromatic ring atoms, and may be substituted in each case by one or more R1 radicals, preferably nonaromatic R1 radicals. Most preferably, R 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 and may be substituted in each case by one or more R1 radicals, preferably nonaromatic R1 radicals. R here, in the case of an electron-rich heteroaromatic ring system, binds to the base skeleton via a carbon atom of the electron-rich heteroaryl group, as described above. In a preferred embodiment of the invention, neither R nor any of the substituents R1 or R2 that are bonded to R contains a carbazole group.
Suitable aromatic or heteroaromatic ring systems R 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 which may be joined via the 1 or 2 position, indole, benzofuran, benzothiophene which may be joined via the 1, 2, 3 or 4 position, dibenzofuran, carbazole 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, quinazoline, benzimidazole, phenanthrene, triphenylene or a combination of two or three of these groups, each of which may be substituted by one or more R1 radicals. When R is a heteroaryl group, especially triazine, pyrimidine or quinazoline, preference may also be given to aromatic or heteroaromatic R1 radicals on this heteroaryl group.
The R groups here, when they are an aromatic or heteroaromatic ring system, are preferably selected from the groups of the following formulae R-1 to R-70:
where R1 has the definitions given above, the dotted bond represents the bond to a carbon atom in the base skeleton in formula (1) or in the preferred embodiments, and in addition:
In a preferred embodiment, Ar3 encompasses bivalent aromatic or heteroaromatic ring systems based on the groups of the R-1 to R-70, where m=0.
When the abovementioned R-1 to R-70 groups for R have two or more A1 groups, possible options for these include all combinations from the definition of A1. Preferred embodiments in that case are those in which one A1 group is O or S and the other A1 group is C(R)2 or C(R1)2 or in which both A1 groups are S or O or in which both A1 groups are O or S.
When A1 is C(R1)2, the substituents R1 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 R2 radicals. Most preferably, R1 is a methyl group or a phenyl group. In this case, the R1 radicals together may also form a ring system, which leads to a spiro system.
When Y is CR2, the substituents R 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 electron-deficient heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may also be substituted by one or more R1 radicals. Most preferably, these substituents R are a methyl group or a phenyl group. In this case, the R radicals together may also form a ring system, which leads to a spiro system.
In a further embodiment of the invention, at least one R radical in the compound of the formula (1) or the embodiments that are cited as preferred is an electron-deficient heteroaromatic ring system. This electron-deficient heteroaromatic ring system is preferably selected from the above-depicted R-35 to R-38, R-45, R-46, R-64 and R-66 to R-70 groups.
In a further preferred embodiment of the invention, R1 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, OR2, a straight-chain alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms, where the alkyl or alkenyl group may in each case be substituted by one or more R2 radicals, and where one or more nonadjacent CH2 groups may be replaced by O, or an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted in each case by one or more R2 radicals; at the same time, two or more R1 radicals together may form an aliphatic ring system.
In a particularly preferred embodiment of the invention, R1 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 R2 radicals, but is preferably unsubstituted, 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 R2 radicals, but is preferably unsubstituted. R1 here, in the case of an electron-rich heteroaromatic ring system, binds to the base skeleton via a carbon atom, as described above.
In a further preferred embodiment of the invention, R2 is the same or different at each instance and is H, F, 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.
In a further preferred embodiment of the invention, all R1 radicals, if they are an aromatic or heteroaromatic ring system, or R2 radicals, if they are aromatic or heteroaromatic groups, are selected from the R-1 to R-70 groups, in which case these, however, are each correspondingly substituted by R2, or by the groups mentioned for R2.
In addition, the R groups do not form aromatic or heteroaromatic groups fused onto the base skeleton of the formula (1).
In a preferred embodiment of the invention, R in the case of an aromatic or heteroaromatic ring system is selected from the groups comprising aromatic ring systems, electron-deficient heteroaromatic ring systems, and dibenzofuran or derivatives thereof or dibenzothiophene or derivatives thereof, each of which may be substituted by one or more R1 radicals.
At the same time, the alkyl groups in compounds of the invention which are processed by vacuum evaporation 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 that 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. It is especially preferable when the Ar, R, R1 and R2 radicals do not contain any fused aryl or heteroaryl groups in which two or more six-membered rings are fused directly to one another. An exception to this is formed by phenanthrene, triphenylene, quinazoline and quinoxaline, 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 schemes 1 and 2. Schemes 1 and 2 show the synthesis of the compounds proceeding from reactants in which corresponding coupling groups such as Br or Cl are present on one of the aromatic six-membered rings in each case.
First of all, the base skeleton of the formula (1) is constructed, having reactive leaving groups, for example chlorine or bromine. These can be replaced by other substituents in a subsequent reaction, for example by aromatic or heteroaromatic substituents R in a Suzuki coupling reaction.
The present invention therefore further provides a process for preparing the compounds of the invention, characterized by the following steps:
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 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. 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. This further compound may also be polymeric.
The compounds of the invention are suitable for use in an electronic device, especially in an organic electroluminescent device.
The present invention therefore 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), 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), dye-sensitized organic solar cells (DSSCs), organic optical detectors, organic photoreceptors, organic field-quench devices (O-FQDs), light-emitting electrochemical cells (LECs), organic laser diodes (O-lasers) and organic plasmon emitting devices, but preferably organic electroluminescent devices (OLEDs), more preferably 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 OLED, especially for white-emitting OLEDs.
The compound of the invention according to the above-detailed embodiments 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 this case, the organic electroluminescent device may contain an emitting layer, or it may contain a plurality of emitting layers, where at least one emitting layer contains at least one compound of the invention as matrix material. In addition, the compound of the invention can also be used in an electron transport layer and/or in a hole blocker layer and/or in a hole transport layer and/or in an exciton 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.
A further preferred 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 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, or dibenzofuran derivatives, for example according to WO 2015/169412, WO 2016/015810, WO 2016/023608, WO 2017/148564 or WO 2017/148565. It is likewise possible for a further phosphorescent emitter having shorter-wavelength emission than the actual emitter to be present as co-host in the mixture, or a compound not involved in charge transport to a significant extent, if at all, as described, for example, in WO 2010/108579.
In a preferred embodiment of the invention, the materials are used in combination with a further matrix material. Preferred co-matrix materials, especially when the compound of the invention is substituted by an electron-deficient heteroaromatic ring system, are selected from the group of the biscarbazoles, the bridged carbazoles, the triarylamines, the dibenzofuranyl-carbazole derivatives or dibenzofuranyl-amine derivatives and the carbazolamines.
Preferred biscarbazoles are the structures of the following formulae (17) and (18):
where Ar, R and A1 are as follows:
In a preferred embodiment of the invention, A1 is CR2.
Ar in the case of the formulae (17) and (18) is preferably an aromatic or heteroaromatic ring system, preferably the same or different at each instance and selected from the groups of the following formulae Ar-1 to Ar-82:
where the dotted line represents the bond to the base skeleton, and in addition:
Preferred embodiments of the compounds of the formulae (17) and (18) are the compounds of the following formulae (17a) and (18a):
where the symbols used have the above-specified definitions according to formula (17) and formula (18).
Examples of suitable compounds of formulae (17) and (18) are the compounds depicted below:
Preferred bridged carbazoles are the structures of the following formula (19):
where A1 and R have the above-specified definitions according to the formulae (17) and (18), and A1 is preferably the same or different at each instance and is selected from the group consisting of NAr and CR2.
Preferred dibenzofuran derivatives are the compounds of the following formula (20):
where the oxygen may also be replaced by sulfur so as to form a dibenzothiophene, L is a single bond or an aromatic or heteroaromatic ring system which has 5 to 30 aromatic ring atoms and may also be substituted by one or more R radicals, and R and Ar have the definitions given above. It is also possible here for the two Ar groups that bind to the same nitrogen atom, or for one Ar group and one L group that bind to the same nitrogen atom, to be bonded to one another, for example to give a carbazole.
Examples of suitable dibenzofuran derivatives are the compounds depicted below.
Preferred carbazolamines are the structures of the following formulae (21), (22) and (23):
where L is an aromatic or heteroaromatic ring system which has 5 to 30 aromatic ring atoms and may be substituted by one or more R radicals, and R and Ar have the above-specified definitions according to formula (17) and formula (18).
Examples of suitable carbazolamine derivatives are the compounds depicted below.
Preferred co-matrix materials, especially when the compound of the invention is substituted by an electron-rich heteroaromatic ring system, for example a carbazole group, are also selected from the group consisting of triazine derivatives, pyrimidine derivatives, quinazoline derivatives and quinoxaline derivatives. Preferred triazine, pyrimidine, quinazoline or quinoxaline derivatives that can be used as a mixture together with the compounds of the invention are the compounds of the following formulae (24), (25), (26) and (27):
where Ar and R have the above-specified definitions according to the formulae (17) and (18).
Particular preference is given to the triazine derivatives of the formula (24) and the quinazoline derivatives of the formula (26), especially the triazine derivatives of the formula (24).
In a preferred embodiment of the invention, Ar in the formulae (24), (25), (26) and (27) is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms, especially 6 to 24 aromatic ring atoms, and may be substituted by one or more R radicals. Suitable aromatic or heteroaromatic ring systems Ar here are the same as set out above as embodiments for Ar, especially the structures Ar-1 to Ar-82, as described above as radicals for the compounds of the formulae (17) and (18).
Examples of suitable triazine compounds that may be used as matrix materials together with the compounds of the invention are the compounds depicted in the following table:
Examples of suitable quinazoline compounds are the compounds depicted in the following table:
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 emitters described above 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, WO 2018/011186, WO 2018/041769, WO 2019/020538, WO 2018/178001, WO 2019/115423 and WO 2019/158453. In general, all phosphorescent complexes as used for phosphorescent OLEDs 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 adduced below.
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 vapor 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 vapor 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 vapor 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.
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 vapor deposition.
Those skilled in the art are generally aware of these methods and are able to apply them 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 are notable for one or more of the following surprising properties:
The invention is illustrated in 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, for example, from Sigma-ALDRICH or ABCR. For the compounds known from the literature, the corresponding CAS numbers are also reported in each case.
7.6 g (23 mmol) of 3-phenylbenzimidazolo[2,1-b][1,3]benzothiazin-12-one is initially charged in 150 ml of DMF. Subsequently, a solution of 4 g (22.5 mmol) of NBS in 100 ml of DMF is added dropwise in the dark at room temperature, the mixture is allowed to come to room temperature and stirring is continued at this temperature for 4 h. Subsequently, 150 ml of water is 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: 7.9 g (19 mmol), 85% of theory, purity by H NMR about 98%.
The following compounds are obtained in an analogous manner:
[2089317-48-4]
In a four-neck flask, 20.9 g (73.0 mmol, 1.00 eq) of 8-chlorobenzimidazolo[2,1-b][1,3]benzothiazin-12-one is dissolved together with 22.2 g (87.6 mmol, 1.20 eq) of bis(pinacolato)diborane and 21.5 g (219 mmol, 3.00 eq) of potassium acetate in 800 ml of dioxane, and the mixture is inertized with argon. Subsequently, 1.79 g (2.19 mmol, 0.03 eq) of 1,1-bis(diphenylphosphino)ferrocene-dichloropalladium(II) complex [95464-05-4] is added and the reaction mixture is stirred at bath temperature 115° C. overnight. After the reaction has ended, the mixture is cooled down to room temperature and the solvent is removed by rotary evaporator. The residue is taken up in 250 ml of dichloromethane and extracted by shaking with 250 ml of water. The aqueous phase is extracted three times with 250 ml of dichloromethane, the combined organic phases are dried over sodium sulfate and the solvent is removed on a rotary evaporator. The resulting solids are washed with ethanol at 60° C. After drying, 22 g (58.0 mmol, 80%) of the desired product is obtained.
The following compounds are obtained in an analogous manner:
[2225171-32-2]
[2225171-21-9]
[2225171-22-0]
[1359997-50-4]
[2055279-89-3 ]
[1807716-96-6]
38.8 g (110.0 mmol) of [3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]boronic acid, 44.7 g (110.0 mmol) of 8-bromo-3-phenylbenzimidazolo[2,1-b][1,3]benzothiazin-12-one and 44.7 g (210.0 mmol) of tripotassium phosphate are suspended in 500 ml of toluene, 500 ml of dioxane and 500 ml of water. To this suspension are added 914 mg (3.0 mmol) of tri-o-tolylphosphine and then 112 mg (0.5 mmol) of palladium(II) acetate, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 200 ml of water and then concentrated to dryness. The residue is recrystallized from toluene and from dichloromethane/iso-propanol and finally sublimed under high vacuum, purity is 99.9%. The yield is 53 g (84 mmol), corresponding to 77% of theory.
The following compounds are obtained in an analogous manner:
[2225171-32-2]
[1251825-65-6]
[2225171-21-9]
[1612243-82-9]
[2225171-22-0]
[1235876-72-8]
[2102200-16-6]
[1251825-65-6]
[2102200-14-4]
[1612243-82-9]
[2102200-15-5]
[1235876-72-8]
[502137-21-5]
[162607-19-4 ]
[56346-55-5]
[1235876-72-8]
[1359997-50-4]
[2138490-96-5]
[2251105-15-2]
[2142681-84-1]
[13599997-44-6]
[654664-63-8]
[13599997-46-8]
[1822311-40-9]
[1822311-40-9]
[2142681-84-1]
[1807716-96-6]
[2138490-96-5]
[1356003-05-8]
[1822311-40-9]
[1356003-05-8]
[1214723-25-7]
[1356003-05-8]
[162607-19-4 ]
[1356003-05-8]
[1235876-72-8]
[2055279-88-2]
1558757-90-6
[2225171-32-2]
[2379459-92-2]
[2055279-89-3]
[867044-33-5]
[1807716-96-6]
[2055279-89-3]
[2173554-94-2]
[2055279-89-3]
[2055279-89-3]
[1214723-25-7]
[2102200-20-2]
[1251825-65-6]
[162607-19-4]
[1251825-65-6]
[2089317-40-6]
[1235876-72-8]
[2089317-43-9]
[2138490-96-5]
[1356003-05-8]
[56346-55-5]
[162607-19-4]
[2055279-89-3]
[1266389-18-7]
[2225171-22-0]
Production of the OLEDs
Examples E1 to E20 which follow (see table 1) present the use of the materials of the invention in OLEDs.
Pretreatment for examples E1 to E20: Glass plates coated with structured ITO (indium tin oxide) of thickness 50 nm are treated prior to coating with an oxygen plasma, followed by an argon plasma. These plasma-treated glass plates form the substrates to which the OLEDs are applied.
The OLEDs 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 aluminum layer of thickness 100 nm. The exact structure of the OLEDs can be found in table 1. The materials required for production of the OLEDs are shown in table 2.
All materials are applied by thermal vapor 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 EG1:IC2:TEG1 (49%:44%:7%) mean here that the material EG1 is present in the layer in a proportion by volume of 49%, IC2 in a proportion of 44% and TEG1 in a proportion of 7%. Analogously, the electron transport layer may also consist of a mixture of two materials.
The OLEDs are characterized in a standard manner. For this purpose, electroluminescence spectra, current efficiency (CE, measured in cd/A) and external quantum efficiency (EQE, measured in %) are determined as a function of luminance, calculated from current-voltage-luminance characteristics assuming Lambertian emission characteristics. Electroluminescence spectra are determined at a luminance of 1000 cd/m2, and these are used to calculate the CIE 1931 x and y color coordinates. The results thus obtained can be found in table 3.
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=80% in table 3 means that the lifetime reported in the LT column corresponds to the time after which the luminance falls to 80% of its starting value.
Use of the Materials of the Invention in OLEDs
The inventive compounds EG1 to EG18 can be used in examples E1 to E18 as matrix material in the emission layer of phosphorescent green OLEDs. The inventive compounds EG5 and EG8 can be used in examples E19 to E20 as electron transporter in the ETM layer of phosphorescent green OLEDs.
It can be seen here that a compound containing a carbazole substituent bonded to the base skeleton via a carbon atom, when used as hole-transporting host material, leads to a higher efficiency than a corresponding compound in which the carbazole substituent is bonded to the base skeleton via the nitrogen atom (comparison of V4 with E18).
| Number | Date | Country | Kind |
|---|---|---|---|
| 20189856.6 | Aug 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/071610 | 8/3/2021 | WO |
