Materials for organic electroluminescent devices

The invention relates to compounds which are suitable for use in electronic devices, and to electronic devices, in particular organic electroluminescent devices, containing said compounds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. § 371) of PCT/EP2020/074184, filed Aug. 31, 2020, which claims benefit of European Application No. 19194922.1, filed Sep. 2, 2019, both of which are incorporated herein by reference in their entirety.

The present invention relates to electronic devices, especially organic electroluminescent devices, comprising triazinone derivatives.

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 or charge transport 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 or WO 2013/064206.

The problem addressed by the present invention is that of providing 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 is a further object of the present invention to provide further organic semiconductors for organic electroluminescent devices, in order thus to enable the person skilled in the art to have a greater possible choice of materials for the production of OLEDs.

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 low operating voltage. The present invention therefore provides these compounds and electronic devices, especially organic electroluminescent devices, comprising these compounds.

The present invention provides an electronic device comprising at least one compound of formula (1)

where the symbols used are as follows:Z is the same or different at each instance and is O or S;A is R or Z;Rbis Ar or a free electron pair;where, when A=Z, the oxygen or sulfur atom represented by Z is bonded to the carbon atom via a double bond, and Rbis Ar;in addition, Rbis a free electron pair when A=R, and there is a double bond between the carbon atom to which A is bonded and the nitrogen atom to which Rbis bonded;Rais the same or different and is R, or the two Ragroups together with the nitrogen atom and the carbon atom to which they bind form a group of one of the following formulae (2), (3) and (4):

where the dotted bond in each case indicates the linkage within formula (1);X is the same or different at each instance and is CR or N; or two adjacent X groups are a group of the following formula (5) or (6):

where the dotted bonds indicate the linkage of this group in the formula (2), formula (3) or formula (4);Y is the same or different at each instance and is CR or N;W is the same or different at each instance and is NAr, O, S or C(R)2;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 R radicals;R is the same or different at each instance and is H, D, F, Cl, Br, I, N(Ar′)2, N(R1)2, OAr′, SAr, CN, NO2, OR1, SR1, COOR1, C(═O)N(R1)2, Si(R1)3, B(OR1)2, C(═O)R1, P(═O)(R1)2, S(═O)R1, S(═O)2R1, OSO2R1, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R1radicals, where one or more nonadjacent CH2groups may be replaced by Si(R1)2, C═O, NR1, O, S or CONR1, 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 R1radicals; at the same time, two R radicals together may also form an aliphatic, heteroaliphatic, aromatic or heteroaromatic ring system;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 R1radicals;R1is the same or different at each instance and is H, D, F, Cl, Br, I, N(R2)2, CN, NO2, OR2, SR2, Si(R2)3, B(OR2)2, C(═O)R2, P(═O)(R2)2, S(═O)R2, S(═O)2R2, OSO2R2, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may each be substituted by one or more R2radicals, where one or more nonadjacent CH2groups may be replaced by Si(R2)2, C═O, NR2, O, S or CONR2and where one or more hydrogen atoms in the alkyl, alkenyl or alkynyl group may be replaced by D, F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted in each case by one or more R2radicals; at the same time, two or more R1radicals together may form an aliphatic ring system;R2is the same or different at each instance and is H, D, F, CN or an aliphatic, aromatic or heteroaromatic organic radical, especially a hydrocarbyl radical, having 1 to 20 carbon atoms, in which one or more hydrogen atoms may also be replaced by F.

If two adjacent X groups are one of the formulae (5) and (6), the remaining X groups in formulae (2) and (4) are the same or different and are CR or N. In addition, it is also possible in formula (2) or (4) that each of two adjacent pairs X are groups of the formula (5) or (6), such that the group of the formula (2) or (4) may also in each case contain two groups of the formula (5) or (6).

In a preferred embodiment of the invention, the compound of the formula (1) contains at least one substituent Ar, or it contains at least one substituent R which is an aromatic or heteroaromatic ring system.

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. 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 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.

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.

The wording that two or more radicals together may form an aliphatic ring, in the context of the present description, shall 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 shall be illustrated by the following scheme:

The choice of A and Rbgroups gives rise to the compounds of the following formulae (7) and (8):

where the symbols used have the definitions given above.

In a preferred embodiment of the compounds detailed above and hereinafter, Z is O, and so preferred compounds of the formula (7) are the compounds of the following formula (7a) and preferred compounds of the formula (8) are the compounds of the following formula (8a):

where the symbols used have the definitions given above.

In one embodiment, the two Ragroups together with the nitrogen atom and the carbon atom to which they bind form a group of formula (2), (3) or (4). It is preferable here for formula (2) that not more than one X group is N. More preferably, all X are the same or different and are CR, or two adjacent X are a group of the formula (5) or (6) and the remaining X are the same or different at each instance and are CR. It is additionally preferable for formula (3) that the two X are the same or different and are CR, or that the two X together are a group of the formula (5). It is additionally preferable for formula (4) that not more than one X group is N and the remaining X are the same or different and are CR or a group of the formula (5) or (6). When, in formula (4), an X group is N, this is preferably an X group in the five-membered ring. It is additionally preferable when, in formula (4), the two X groups in the six-membered ring together are a group of the formula (5) or (6).

In this case, in the formulae (5) and (6), preferably not more than one Y group is N. More preferably, all Y groups are the same or different at each instance and are CR.

Preferred embodiments of the formula (2) are the groups of the following formulae (2a) to (2m):

where the symbols used have the definitions given above and the dotted bond in each case indicates the linkage within formula (1).

Preferred embodiments of the formulae (2a), (2b) and (2g) are the structures of the following formulae (2a-1), (2b-1) and (2g-1):

where the symbols used have the definitions given above.

Preferred embodiments of the formula (3) are the groups of the following formulae (3a) and (3b):

where the symbols used have the definitions given above and the dotted bond in each case indicates the linkage within formula (1).

Preferred embodiments of the formula (3b) are the structures of the following formula (3b-1):

where the symbols used have the definitions given above.

Preferred embodiments of the formula (4) are the structures of the following formulae (4a) to (4k):

where the symbols used have the definitions given above and the dotted bond in each case indicates the linkage within formula (1).

Preferred embodiments of the formulae (4a), (4b), (4c), (4d) and (4e) are the structures of the following formulae (4a-1), (4b-1), (4c-1), (4d-1) and (4e-1):

where the symbols used have the definitions given above.

In a further preferred embodiment of the invention, W is the same or different at each instance and is NAr, O or S.

It is possible here for the structures of the formulae (7) and (8) to be combined as desired with the structures of the formulae (2a) to (2m), (3a), (3b) and (4a) to (4k).

In one embodiment of the invention, the two Ragroups are the same or different at each instance and are R, such that the compounds are those of the following formulae (7-1) and (8-1):

where the symbols used have the definitions given above, where Z is preferably O.

In a further embodiment of the invention, the Raradicals are a group of the formula (2), (3) or (4), and the compounds of the formula (7) are compounds of the following formulae (7-2) to (7-9):

where the symbols have the definitions given above.

Preferred embodiments of the structures of the formulae (7-1) to (7-9) are the structures of the following formulae (7-1a) to (7-9a):

where the symbols have the definitions given above.

If the Raradicals are a group of the formula (2), (3) or (4), preferred embodiments of the formula (8) are the compounds of the following formulae (8-2) to (8-11):

where the symbols have the definitions given above.

Preferred embodiments of the structures of the formulae (8-1) to (8-11) are the structures of the following formulae (8-1a) to (8-11a):

where the symbols have the definitions given above.

Particular preference is given here to the structures of the formulae (7-1a), (7-2a), (7-4a), (7-5a), (7-7a), (7-9a), (8-1a), (8-2a), (8-7a), (8-8a) and (8-9a).

There follows a description of preferred substituents Ar, R, Ar′, R1and R2in the compounds of the invention. In a particularly preferred embodiment of the invention, the preferences specified hereinafter for Ar, R, Ar′, R1and R2occur simultaneously and are applicable to the structures of the formula (1) and to all preferred embodiments detailed above.

In a preferred embodiment of the invention, in formula (1), when A=R, this R radical is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and which may be substituted by one or more R1radicals. Correspondingly, it is preferable that the R radical explicitly shown in formulae (8) and (8-1) to (8-11) which is bonded to the triazinone is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R1radicals.

In a preferred embodiment of the invention, Ar is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R radicals. More preferably, Ar 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 13 aromatic ring atoms, and may be substituted by one or more, preferably nonaromatic, R radicals. When Ar is a heteroaryl group, especially triazine, pyrimidine, quinazoline or carbazole, preference may also be given to aromatic or heteroaromatic substituents R on this heteroaryl group. It may further be preferable when Ar is substituted by an N(Ar′)2group, such that the Ar substituent constitutes a triarylamine or triheteroarylamine group overall.

Suitable aromatic or heteroaromatic ring systems Ar are the same or different at each instance and are selected from the group consisting of 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, 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, quinazoline, benzimidazole, 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. When Ar is a heteroaryl group, especially triazine, pyrimidine, quinazoline or carbazole, preference may also be given to aromatic or heteroaromatic R radicals on this heteroaryl group.

Ar here is preferably the same or different at each instance and is selected from the groups of the following formulae Ar-1 to Ar-83:

where R has the definitions given above, the dotted bond represents the bond to the nitrogen atom and, in addition:Ar1is the same or different at each instance and is a bivalent aromatic or heteroaromatic ring system which has 6 to 18 aromatic ring atoms and may be substituted in each case by one or more R radicals;A1is the same or different at each instance and is NR, O, S or C(R)2;n is 0 or 1, where n=0 means that no A1group is bonded at this position and R radicals are bonded to the corresponding carbon atoms instead;m is 0 or 1, where m=0 means that the Ar4group is absent and that the corresponding aromatic or heteroaromatic group is bonded directly to the nitrogen atom.

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, N(Ar′)2, 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 R1radicals, but is preferably unsubstituted, and where one or more nonadjacent CH2groups 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 R1radicals; at the same time, two R radicals together may also form an aliphatic, 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, N(Ar′)2, 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 R1radicals, 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 R1radicals, preferably nonaromatic R1radicals. 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 R1radicals, preferably nonaromatic R1radicals. It may additionally be preferable when R is a triaryl-or-heteroarylamine group which may be substituted by one or more R1radicals. This group is one embodiment of an aromatic or heteroaromatic ring system, in which case two or more aryl or heteroaryl groups are joined to one another by a nitrogen atom. When R is a triaryl-or-heteroarylamine group, this group preferably has 18 to 30 aromatic ring atoms and may be substituted by one or more R1radicals, preferably nonaromatic R1radicals.

In a further preferred embodiment of the invention, Ar′ is an aromatic or heteroaromatic ring system which has 6 to 30 aromatic ring atoms and may be substituted by one or more R1radicals. In a particularly preferred embodiment of the invention, Ar′ is 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 by one or more, preferably nonaromatic, R1radicals.

Suitable aromatic or heteroaromatic ring systems R 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 which may be joined via the 1 or 2 position, 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, quinazoline, benzimidazole, phenanthrene, triphenylene or a combination of two or three of these groups, each of which may be substituted by one or more R1radicals. When R or Ar′ is a heteroaryl group, especially triazine, pyrimidine, quinazoline or carbazole, preference may also be given to aromatic or heteroaromatic R1radicals on this heteroaryl group.

The R groups here, when they are an aromatic or heteroaromatic ring system, or Ar′ are preferably selected from the groups of the following formulae R-1 to R-83:

where R1has the definitions given above, the dotted bond represents the bond to a carbon atom of the base skeleton in formulae (1), (2) and (3) or in the preferred embodiments, or to the nitrogen atom in the N(Ar′)2group and, in addition:Ar1is the same or different at each instance and is a bivalent aromatic or heteroaromatic ring system which has 6 to 18 aromatic ring atoms and may be substituted in each case by one or more R1radicals;A1is the same or different at each instance and is C(R1)2, NR1, O or S;n is 0 or 1, where n=0 means that no A1group is bonded at this position and R1radicals are bonded to the corresponding carbon atoms instead;m is 0 or 1, where m=0 means that the Ar4group is absent and that the corresponding aromatic or heteroaromatic group is bonded directly to a carbon atom of the base skeleton in formula (1) or in the preferred embodiments, or to the nitrogen atom in the N(Ar′)2group; with the proviso that m=1 for the structures (R-12), (R-17), (R-21), (R-25), (R-26), (R-30), (R-34), (R-38) and (R-39) when these groups are embodiments of Ar′.

When the abovementioned Ar-1 to Ar-83 groups for Ar and R-1 to R-83 groups for R or Ar′ have two or more A1groups, possible options for these include all combinations from the definition of A1. Preferred embodiments in that case are those in which one A1group is NR or NR1and the other A1group is C(R)2or C(R1)2or in which both A1groups are NR or NR1or in which both A1groups are O. In a particularly preferred embodiment of the invention, in Ar, R or Ar′ groups having two or more A1groups, at least one A1group is C(R)2or C(R1)2or is NR or NR1.

When A1is NR or NR1, the substituent R or R1bonded 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 R1or R2radicals. In a particularly preferred embodiment, this R or R1substituent is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, preferably 6 to 12 aromatic ring atoms, and which does not have any fused aryl groups or 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 R1or R2radicals. Particular preference is given to phenyl, biphenyl, terphenyl and quaterphenyl having bonding patterns as listed above for Ar-1 to Ar-11 or R-1 to R-11, where these structures may be substituted by one or more R1or R2radicals, but are preferably unsubstituted.

When A1is C(R)2or C(R1)2, the substituents R or R1bonded 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 which has 5 to 24 aromatic ring atoms and may also be substituted by one or more R1or R2radicals. Most preferably, R or R1is a methyl group or a phenyl group. In this case, the R or R1radicals together may also form a ring system, which leads to a spiro system.

In one embodiment of the invention, at least one R radical is an electron-rich heteroaromatic ring system. This electron-rich heteroaromatic ring system is preferably selected from the above-depicted R-13 to R-42 groups, where, in the R-13 to R-16, R-18 to R-20, R-22 to R-24, R-27 to R-29, R-31 to R-33 and R-35 to R-37 groups, at least one A1group is NR1where R1is preferably an aromatic or heteroaromatic ring system, especially an aromatic ring system. Particular preference is given to the R-15 group with m=0 and A1=NR1.

In a further embodiment of the invention, at least one R radical is an electron-deficient heteroaromatic ring system. This electron-deficient heteroaromatic ring system is preferably selected from the above-depicted R-47 to R-50, R-57, R-58 and R-76 to R-83 groups.

In a further embodiment of the invention, Ar is an electron-deficient heteroaromatic ring system. This electron-deficient heteroaromatic ring system is preferably selected from the above-depicted Ar-47 to Ar-50, Ar-57, Ar-58 and Ar-76 to Ar-83 groups.

In a further preferred embodiment of the invention, R1is 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 R2radicals, and where one or more nonadjacent CH2groups 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 R2radicals; at the same time, two or more R1radicals together may form an aliphatic ring system. In a particularly preferred embodiment of the invention, R1is 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 R2radicals, 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 R2radicals, but is preferably unsubstituted.

In a further preferred embodiment of the invention, R2is 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.

Further suitable Ar, R or Ar′ groups are groups of the formula —Ar4—N(Ar2)(Ar3) where Ar2, Ar3and Ar4are 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 R or R1radicals. Ar results in such a group when the Ar group is substituted by an N(Ar′)2group. The total number of aromatic ring atoms in Ar2, Ar3and Ar4here is not more than 60 and preferably not more than 40.

In this case, Ar4and Ar2may also be bonded to one another and/or Ar2and Ar3to one another via a group selected from C(R1)2, NR1, O or S. Preferably, Ar4and Ar2are joined to one another and Ar2and Ar3to 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, Ar3and Ar4groups are bonded to one another.

Preferably, Ar4is an aromatic or heteroaromatic ring system which has 6 to 24 aromatic ring atoms, especially 6 to 12 aromatic ring atoms, and may be substituted in each case by one or more R1radicals. More preferably, Ar4is 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 R1radicals, but are preferably unsubstituted. Most preferably, Ar4is an unsubstituted phenylene group. This is especially true when Ar4is bonded to Ar2via a single bond.

Preferably, Ar2and Ar3are 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 R1radicals. Particularly preferred Ar2and Ar3groups 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, triphenylene or combinations of two, three or four of these groups, each of which may be substituted by one or more R1radicals. More preferably, Ar2and Ar3are the same or different at each instance and are an aromatic ring system which has 6 to 24 aromatic ring atoms and may be substituted by one or more R1radicals, especially selected from the groups 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.

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 that the Ar, R, Ar′, R1and R2radicals 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 and quinazoline, 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 claim1. In a particularly preferred embodiment of the invention, the abovementioned preferences occur simultaneously.

Examples of suitable compounds according to the above-detailed embodiments are the compounds detailed in the following table:

The base structure of the compounds of the invention is known in the literature. These can be prepared and functionalized by the routes outlined in the schemes that follow.

The compounds of the formula (1) or the above-detailed preferred embodiments are used in accordance with the invention in an electronic device, especially in an organic electroluminescent device.

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 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 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 formula (1) or of the preferred embodiments 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 formula (1) or of the preferred embodiments, 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 formula (1) or of the preferred embodiments 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, 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. The compounds of the formula (1) or the preferred embodiments are electron-deficient compounds. Preferred co-matrix materials are therefore selected from the group of the biscarbazoles, the bridged carbazoles, the triarylamines, the dibenzofuran-carbazole derivatives or dibenzofuran-amine derivatives, and the carbazoleamines.

Preferred biscarbazoles are the structures of the following formulae (9) and (10):

where R, Ar1and A1have the definitions given above. In a preferred embodiment of the invention, A1is CR2.

Preferred embodiments of the compounds of the formulae (9) and (10) are the compounds of the following formulae (9a) and (10a):

where the symbols used have the definitions given above.

Examples of suitable compounds of formulae (9) and (10) are the compounds depicted below:

Preferred bridged carbazoles are the structures of the following formula (11):

where A1and R have the definitions given above and A1is preferably the same or different at each instance and is selected from the group consisting of NAr1and CR2.

Preferred dibenzofuran derivatives are the compounds of the following formula (12):

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 Ar1have the definitions given above. It is also possible here for the two Ar1groups that bind to the same nitrogen atom, or for one Ar1group 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 carbazoleamines are the structures of the following formulae (13), (14) and (15):

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 Arb have the definitions given above.

Examples of suitable carbazoleamine derivatives are the compounds depicted below.

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 and WO 2018/041769, WO 2019/020538, WO 2018/178001, WO 2019/115423, and the as yet unpublished patent application EP 18156388.3. 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 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 10−5mbar, preferably less than 10−6mbar. However, it is also possible that the initial pressure is even lower, for example less than 10−7mbar.

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 10−5mbar 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.

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 formula (1).

Compounds of formula (1) containing at least one dibenzofuran, dibenzothiophene or carbazolyl group in one of the substituents are novel.

The present invention therefore further provides compounds of formula (1′)

where the symbols used have the definitions given above, characterized in that the compound contains a heteroaryl group or a heteroaromatic ring system in at least one of the substituents Ar or R. The heteroaryl group here is preferably selected from the group consisting of dibenzofuran, dibenzothiophene and carbazole.

The preferred embodiments detailed above for the compound of the formula (1) are likewise also applicable here to the formula (1′).

Preferred heteroaryl groups here are the Ar-12 to Ar-42, Ar-47 to Ar-68, Ar-76 to Ar-83, R-12 to R-42, R-47 to R-68 and R-76 to R-83 groups shown above.

The materials of the invention and the organic electroluminescent devices of the invention are notable for one or more of the following surprising advantages over the prior art:1. OLEDs containing the compounds of formula (1) or (1′) as matrix material for phosphorescent emitters lead to long lifetimes.2. OLEDs containing the compounds of formula (1) or (1′) lead to high efficiencies. This is especially true when the compounds are used as matrix material for a phosphorescent emitter.3. OLEDs containing the compounds of formula (1) or (1′) lead to low operating voltages. This is especially true when the compounds are used as matrix material for a phosphorescent emitter.

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 produce further inventive electronic devices without exercising inventive skill.

EXAMPLES

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.

Synthesis Examples

To a solution of 48.8 g (150 mmol) of 1,4,6-triphenyl-1,3,5-triazin-2-one in chloroform (900 ml) is added N-bromosuccinimide (26.6 g, 150 mmol) in portions at 0° C. with exclusion of light, and the mixture is stirred at this temperature for 2 h. The reaction is ended by addition of sodium sulfite solution and the mixture is stirred at room temperature for a further 30 min. After phase separation, the organic phase is washed with water and the aqueous phase is extracted with dichloromethane. The combined organic phases are dried over sodium sulfate and concentrated under reduced pressure. The residue is dissolved in toluene and filtered through silica gel. Subsequently, the crude product is recrystallized from toluene/heptane. Yield: 45 g (112 mmol), 75% of theory, colorless solid.

The following compounds can be obtained analogously:

62.8 g (155 mmol) of 1-(4-bromophenyl)-4,6-diphenyl-1,3,5-triazin-2-one, 41 g (172 mmol) of 9,9-dimethyl-9H-fluorene-2-boronic acid and 36 g (340 mmol) of sodium carbonate are suspended in 1000 ml of ethylene glycol dimethyl ether and 280 ml of water. 1.8 g (1.5 mmol) of tetrakis(triphenylphosphine)palladium(0) are added to this suspension, and the reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, filtered through silica gel and then concentrated to dryness. The product is purified via column chromatography on silica gel with toluene/heptane (1:2) and finally sublimed under high vacuum (p=5×10−7mbar) (99.9% purity). The yield is 57 g (112 mmol), corresponding to 72% of theory.

The following compounds are prepared in an analogous manner:

25.8 g (40 mmol) of 6-phenyl-1H-quinazoline-2,4-dione, 61.2 g (85 mmol) of 4-iodobenzene, 44.7 g (320 mmol) of potassium carbonate, 3 g (16 mmol) of copper(I) iodide and 3.6 g (16 mmol) of 1,3-di(pyridin-2-yl)propane-1,3-dione are stirred in 100 ml of DMF at 150° C. for 30 h. The solution is diluted with water and extracted twice with ethyl acetate. The combined organic phases are dried over Na2SO4and concentrated by rotary evaporation. The residue is purified by chromatography (EtOAc/hexane: ⅔). The residue is recrystallized from toluene and finally sublimed under high vacuum (p=5×10−5mbar). The purity is 99.9%. The yield is 20.8 g (28.8 mmol); 72% of theory.

The following compounds are prepared in an analogous manner:

20.4 g (50 mmol) of 9-phenyl-3,3′-bi-9H-carbazole and 17.1 g (50 mmol) of 7-bromo-2-phenylpyrido[1,2-a][1,3,5]triazin-4-one are dissolved in 400 ml of toluene under an argon atmosphere. 1.0 g (5 mmol) of tri-tert-butylphosphine is added and the mixture is stirred under an argon atmosphere. 0.6 g (2 mmol) of Pd(OAc)2is added and the mixture is stirred under an argon atmosphere, and then 9.5 g (99 mmol) of sodium tert-butoxide are added. The reaction mixture is stirred under reflux for 24 h. After cooling, the organic phase is separated, washed three times with 200 ml of water, dried over MgSO4and filtered, and the solvent is removed under reduced pressure. The residue is purified by column chromatography using silica gel (eluent: DCM/heptane (1:3)). The residue is subjected to hot extraction with toluene and recrystallized from toluene/n-heptane and finally sublimed under high vacuum. The yield is 28.4 g (42 mmol), corresponding to 85% of theory.

The following compounds can be prepared analogously:

To 20 g (50 mmol) of 3-bromo-4-(2-bromophenyl)dibenzofuran are added 500 ml of toluene, 2.3 g (2.5 mmol) of tris(dibenzylideneacetone)dipalladium(0), 10 ml of 1 M t-Bu3P in toluene and 11.5 g (120 mmol) of sodium tert-butoxide. Subsequently, 8.8 g (40 mmol) of 2-amino-[1,3,5]triazino[2,1-b][1,3]benzoxazol-4-one is added. The mixture is heated to 110° C. for 20 h, then cooled to room temperature, and 400 ml of water is added. The mixture is extracted with ethyl acetate, then the combined organic phases are dried over sodium sulfate and concentrated under reduced pressure. The residue is recrystallized from toluene and from dichloromethane/iso-propanol and finally sublimed under high vacuum. The purity is 99.9%. The yield is 10.6 g (24.5 mmol), corresponding to 49% of theory.

The following compounds can be prepared analogously:

Reactant 1Reactant 2ProductYield1f45%2f51%3f43%4f41%5f46%6f39%
Production of the OLEDs

Examples E1 to E27 which follow (see table 1) present the use of the materials of the invention in OLEDs.

Pretreatment for examples E1 to E27: 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. What is meant here by details given in such a form as EG1:IC2:TEG1 (49%:44%:7%) is that the material EG1 is present in the layer in a proportion by volume of 49%, IC2 in a proportion by volume of 44%, and TEG1 in a proportion by volume 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.

Compounds EG1 to EG11 and EG17 to EG25 are used in examples E1 to E20 as matrix material in the emission layer of phosphorescent green OLEDs. Compounds EG12 to EG16 are used in examples E21 to E25 as matrix material in the emission layer of phosphorescent red OLEDs. Compounds EG5 to EG7 are used in examples E26 to E27 as electron transporter in the ETM layer of phosphorescent green OLEDs.

TABLE 2Structural formulae of the materials for the OLEDs