Patent Application
20220416172
The present invention relates to organic electroluminescent devices comprising benzothiazine derivatives, and to specific benzothiazine derivatives for use in electronic devices, in particular in organic electroluminescent devices.
The structure of organic electroluminescent devices (OLEDs) in which organic semiconductors are employed as functional materials is described, for example in U.S. Pat. No. 4,539,507. The emitting materials employed here are very often organometallic complexes which exhibit phosphorescence. For quantum-mechanical reasons, an up to four-fold increase in efficiency is possible using phosphorescent instead of fluorescent emitters. In general, however, there is still a need for improvement in the case of OLEDs, in particular also in the case of OLEDs which exhibit triplet emission (phosphorescence), for example with respect to efficiency, operating voltage and lifetime.
The properties of phosphorescent OLEDs are not only determined by the triplet emitters but also by the other materials used together with triplet emitters in OLEDs, such as matrix materials, also called host materials. Improvements in these materials and their charge-transport properties can thus also result in significant improvements in the OLED properties.
Thus, the choice of the matrix material in an emission layer comprising a phosphorescent emitter has a great influence on OLEDs properties, especially in terms of efficiency. The matrix material limits the quenching of excited states of emitter molecules by energy transfer.
The object of the present invention is the provision of OLEDs and materials, which are suitable for use in an OLED. More particularly, the object of the present invention is the provision of compounds, which are particularly suitable as matrix material for phosphorescent emitters in an OLED, but also as hole-transport material (HTM), electron-blocking material (EBM), electron-transport material (ETM), hole-blocking material (HBM) depending on the specific structure and radicals present in the compound. A further object of the present invention is to provide further organic semiconductors for organic electroluminescent devices to provide the person skilled in the art with a greater possible choice of materials for the production of OLEDs.
Surprisingly, it has now been found that OLEDs comprising dibenzothiazine derivatives, as described in greater detail below, exhibit excellent properties, particularly when the dibenzothiazine derivatives are employed as matrix material for red phosphorescent emitters. Indeed, these compounds lead to OLEDs exhibiting very good properties in terms of lifetime and/or efficiency and/or electroluminescent emission. The present invention therefore relates to OLEDs comprising dibenzothiazine derivatives, to specific dibenzothiazine derivatives and to electronic devices, in particular organic electroluminescent devices, which comprise these specific dibenzothiazine derivatives. The present invention also relates to mixtures and formulations comprising these compounds.
Dibenzothiazine derivatives and their synthesis are known from the prior art (for example in Ma et. al, J. Org. Chem. 2019, 84, 450-457, Hanchate et al., J. Org. Chem. 2019, 84, 8248-8255, KR10-1834228 or Yongpruksa et al., Org. Biomol. Chem., 2011, 9,7979).
The present invention therefore relates to an organic electroluminescent device comprising an anode, a cathode and at least one organic layer between the cathode and the anode, characterized in that the at least one organic layer comprises a compound of the formula (1),
where the following applies to the symbols and indices used:
Y stands for CRY or N; with the proviso that at least two adjacent groups Y form a condensed aromatic or heteroaromatic ring system with the benzothiazine ring of formula (1);
RS, RY stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R)2, N(Ar)2, NO2, Si(R)3, B(OR)2, OSO2R, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R;
R stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R′)2, N(Ar)2, NO2, Si(R′)3, B(OR′)2, OSO2R′, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R′, where in each case one or more non-adjacent CH2 groups may be replaced by R′C═CR′, C≡C, Si(R′)2, Ge(R′)2, Sn(R′)2, C═O, C═S, C═Se, P(═O)(R′), SO, SO2, O, S or CONR′ and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R′, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R′; where two adjacent substituents R may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R′;
Ar is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case also be substituted by one or more radicals R′; and
R′ stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or abranched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, where in each case one or more non-adjacent CH2 groups may be replaced by SO, SO2, O, S and where one or more H atoms may be replaced by D, F, Cl, Br or I, or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms.
Furthermore, the following definitions of chemical groups apply for the purposes of the present application:
Adjacent radicals in the sense of the present invention are radicals which are bonded to atoms which are linked directly to one another or which are bonded to the same atom.
An aryl group in the sense of this invention contains 6 to 60 aromatic ring atoms; a heteroaryl group in the sense of this invention contains 5 to 60 aromatic ring atoms, at least one of which is a heteroatom. The hetero atoms are preferably selected from N, O and S. This represents the basic definition. If other preferences are indicated in the description of the present invention, for example with respect to the number of aromatic ring atoms or the heteroatoms present, these apply.
An aryl group or heteroaryl group here is taken to mean either a simple aromatic ring, i.e. benzene, or a simple heteroaromatic ring, for example pyridine, pyrimidine or thiophene, or a condensed (annellated) aromatic or heteroaromatic polycycle, for example naphthalene, phenanthrene, quinoline or carbazole. A condensed (annellated) aromatic or heteroaromatic polycycle in the sense of the present application consists of two or more simple aromatic or heteroaromatic rings condensed with one another.
An aryl or heteroaryl group, which may in each case be substituted by the above-mentioned radicals and which may be linked to the aromatic or heteroaromatic ring system via any desired positions, is taken to mean, in particular, groups derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, fluoranthene, benzanthracene, benzophenanthrene, tetracene, pentacene, benzopyrene, 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, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, pyrazine, phenazine, 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.
An aryloxy group in accordance with the definition of the present invention is taken to mean an aryl group, as defined above, which is bonded via an oxygen atom. An analogous definition applies to heteroaryloxy groups.
An aromatic ring system in the sense of this invention contains 6 to 60 C atoms in the ring system. A heteroaromatic ring system in the sense of this invention contains 5 to 60 aromatic ring atoms, at least one of which is a heteroatom. The heteroatoms are preferably selected from N, O and/or S. An aromatic or heteroaromatic ring system in the sense of this invention is intended to be taken to mean a system which does not necessarily contain only aryl or heteroaryl groups, but instead in which, in addition, a plurality of aryl or heteroaryl groups may be connected by a non-aromatic unit (preferably less than 10% of the atoms other than H), such as, for example, an sp3-hybridised C, Si, N or O atom, an sp2-hybridised C or N atom or an sp-hybridised C atom. Thus, for example, systems such as 9,9′-spirobifluorene, 9,9′-diarylfluorene, triarylamine, diaryl ether, stilbene, etc., are also intended to be taken to be aromatic ring systems in the sense of this invention, as are systems in which two or more aryl groups are connected, for example, by a linear or cyclic alkyl, alkenyl or alkynyl group or by a silyl group. Furthermore, systems in which two or more aryl or heteroaryl groups are linked to one another via single bonds are also taken to be aromatic or heteroaromatic ring systems in the sense of this invention, such as, for example, systems such as biphenyl, terphenyl or diphenyltriazine.
An aromatic or heteroaromatic ring system having 5-60 aromatic ring atoms, which may in each case also be substituted by radicals as defined above and which may be linked to the aromatic or heteroaromatic group via any desired positions, is taken to mean, in particular, groups derived from benzene, naphthalene, anthracene, benzanthracene, phenanthrene, benzophenanthrene, pyrene, chrysene, perylene, fluoranthene, naphthacene, pentacene, benzopyrene, biphenyl, biphenylene, terphenyl, terphenylene, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, indolocarbazole, indenocarbazole, 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, 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, fluorubin, 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 combinations of these groups.
For the purposes of the present invention, a straight-chain alkyl group having 1 to 40 C atoms or a branched or cyclic alkyl group having 3 to 40 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms, in which, in addition, individual H atoms or CH2 groups may be substituted by the groups mentioned above under the definition of the radicals, is preferably taken to mean the radicals methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, neohexyl, 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 or octynyl. An alkoxy or thioalkyl group having 1 to 40 C atoms is preferably taken 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, 2,2,2-trifluoroethoxy, 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.
The formulation that two radicals may form a ring with one another is, for the purposes of the present application, intended to be taken to mean, inter alia, that the two radicals are linked to one another by a chemical bond. This is illustrated by the following schemes:
Furthermore, the above-mentioned formulation is also intended to be taken to mean that, in the case where one of the two radicals represents hydrogen, the second radical is bonded at the position to which the hydrogen atom was bonded, with formation of a ring. This is illustrated by the following scheme:
In accordance with a preferred embodiment, the compound of formula (1) is selected from the compounds of formulae (2), (3) and (4);
where the rings Ar1 and Ar2 are aromatic or heteroaromatic ring systems condensed with the benzothiazine ring, which have 5 to 30 aromatic ring atoms and which may be substituted by at least one radical R; and where the symbols Y and RS have the same meaning as above.
Preferably, the rings Ar1 and Ar2 are selected from the rings of the formula (Ar-1) or (Ar-2),
where the dashed bonds between the signs “*” correspond to the common bond of the group of formula (Ar-1) or (Ar-2) with the benzothiazine ring, and where:
V stands for C(R0)2, NRN, O or S; preferably for NRN, O or S, more preferably for NRN;
X stands, identically or differently on each occurrence, for CRX or N; or two adjacent groups X stand for a group of the formula (Ar-3) or (Ar-4),
where the dashed bonds between the signs “*” correspond to the common bond of the group of formula (Ar-3) or (Ar-4) with the group of formulae (Ar-1) or (Ar-2), and furthermore:
R0, RN are on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, Si(R)3, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may be substituted by one or more radicals R, where two adjacent substituents R0 may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R.
More preferably, R0, RN are on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl or alkoxy group having 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl or alkoxy group having 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, O or S, and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where two adjacent substituents R0 may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R.
Preferably, in formula (2), the ring Ar1 corresponds to a ring of formula (Ar-1).
Preferably, in formula (3), the ring Ar2 corresponds to a ring of formula (Ar-1).
Preferably, in formula (4), one ring of the rings Ar1 and Ar2 is a ring of formula (Ar-1), and the other ring is either a ring of formula (Ar-1) or a ring of formula (Ar-2).
In accordance with a very preferred embodiment, the compound of formula (1) is selected from the compounds of formulae (2-1) to (4-5) as depicted below:
where the symbols X, RS, RY and V have the same meaning as above.
In accordance with a particularly preferred embodiment the compound of formula (1) is selected from the compounds of formulae (2-1-1) to (4-5-3) as depicted below:
where the symbols RX, RY, RS, RT and V have the same meaning as above.
More preferably, RS stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, O or S, and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. Even more preferably, RS stands on each occurrence, identically or differently, for a straight-chain alkyl group having 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl group having 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, or an aromatic or heteroaromatic ring systems having 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. Particularly preferably, RS stands on each occurrence, identically or differently, for an aromatic or heteroaromatic ring systems having 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
More preferably, RX, RY and RT stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, N(R)2, N(Ar)2, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, O or S, and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R;
Even more preferably, RX, RY and RT stand on each occurrence, identically or differently, for H, a straight-chain alkyl or alkoxy group having 1 to 20, more preferably 1 to 10 C atoms or a branched or a cyclic alkyl or alkoxy group having 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, or an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
In accordance with a preferred embodiment, the compound of formula (1) comprises at least one radical, preferably one radical RS, RY or R, more preferably one radical RY or R, which corresponds to an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, the compounds of formula (1) comprise at least one radical, preferably one radical RS, RY or R, more preferably one radical RY or R, which stands for an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms selected from the groups of formula (R-1),
where
ArS stands for a single bond or for an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R; and
Ar2 stands for phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, triphenylene, fluoranthene, indole, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, carbazole, indenocarbazole, indolocarbazole, phenanthroline, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinolone, benzopyridine, benzopyridazine, benzopyrimidine, quinazoline, benzimidazole, or a combination of two or three of these groups, each of which may be substituted by one or more radicals R; and
n is an integer equal to 1, 2, 3 or 4, preferably 1 or 2, more preferably 1.
When ArS is a single bond, the group (R-1) corresponds to (R-1sb):
where Ar2 and the index n have the same meaning as above.
More specifically, it is preferred that the compounds of formulae (2-1-1), (2-2-1), (3-1-1) and (3-2-1) comprise at least one radical RS, RX, RY or R, preferably RX, RY or R, more preferably RX or RY, which corresponds to an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, the compounds of formulae (2-1-1), (2-2-1), (3-1-1) and (3-2-1) comprise at least one radical RS, RX, RY or R, preferably RX, RY or R, more preferably RX or RY, which stands for an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms selected from the groups of formula (R-1) as defined above.
It is also preferred that the compounds of formulae (4-1-1), (4-2-1), (4-2-2), (4-3-1), (4-3-2), (4-4-1), (4-4-2), (4-5-1) and (4-5-2) comprise at least one radical RS, RX or R, preferably RX or R, more preferably RX, which corresponds to an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, the compounds of formulae (4-1-1), (4-2-1), (4-2-2), (4-3-1), (4-3-2), (4-4-1), (4-4-2), (4-5-1) and (4-5-2) comprise at least one radical RS, RX or R, preferably RX or R, more preferably RX, which stands for an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms selected from the groups of formula (R-1) as defined above.
It is also preferred that the compounds of formulae (4-2-3), (4-3-3), (4-4-3) and (4-5-3) comprise at least one radical RS, RX, RT or R, preferably RX, RT or R, more preferably RX or RT, which corresponds to an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, the compounds of formulae (4-2-3), (4-3-3), (4-4-3) and (4-5-3) comprise at least one radical RS, RX, RT or R, preferably RX, RT or R, more preferably RX or RT, which stands for an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms selected from the groups of formula (R-1) as defined above.
Preferably the group of formula (R-1) is selected from a group of formula (R-2),
where the dashed bond indicates the bond to the structure,
where n has the same meaning as above, and where:
A stands, identically or differently on each occurrence, for CRA or N; or two adjacent groups A stand for a group of the formula (Ar-5) or (Ar-6),
where the dashed bonds between the signs “*” correspond to the common bond of the group of formula (Ar-5) or (Ar-6) with the group of formula (R-2), and where:
When ArS is a single bond, the group (R-2) corresponds to the group (R-2sb),
where the symbols have the same meaning as above.
In accordance with a preferred embodiment, the group ArS is a single bond.
In accordance with another preferred embodiment, the group ArS is an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms, which may in each case also be substituted by one or more radicals R. More preferably, the group ArS stands on each occurrence, identically or differently, for phenyl, biphenyl, fluorene, spirobifluorene, naphthalene, phenanthrene, anthracene, dibenzofuran, dibenzothiophene, carbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, benzopyridine, benzopyridazine, benzopyrimidine and quinazoline, each of which may be substituted by one or more radicals R. Particularly preferably, the group ArS stands on each occurrence, identically or differently, for phenyl, biphenyl, fluorene, dibenzofuran, dibenzothiophene and carbazole, each of which may be substituted by one or more radicals R.
Examples of suitable groups ArS, when ArS is not a single bond, are the groups ArS-1) to (ArS-22) depicted in the table below:
where the dashed bonds indicate the bonds to the structure of formula (1), and where the groups (ArS-1) to (ArS-22) may be substituted at each free position by a radical R and where:
RN0, RC0 are on each occurrence, identically or differently, H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where one or more non-adjacent CH2 groups may be replaced by (R)C═C(R), C≡C, O or S and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, or an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, very more preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where optionally two adjacent radicals RC0 can form a mono- or polycyclic, aliphatic, aromatic or heteroaromatic ring system with one another.
Examples of very suitable groups ArS, when ArS is not a single bond, are the groups (ArS-23) to (ArS-67) depicted in the table below:
where the dashed bonds indicate the bonds to the structure of formula (1) and where the groups (ArS-23) to (ArS-67) may be substituted at each free position by a radical R.
Preferably, R stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, N(R′)2, N(Ar)2, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R′, where in each case one or more non-adjacent CH2 groups may be replaced by R′C═CR′, C≡C, O or S and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R′;
where two adjacent substituents R may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R′;
Preferably, Ar is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 40, preferably 4 to 30, more preferably 5 to 24, particularly preferably 5 to 18 aromatic ring atoms, which may in each case also be substituted by one or more radicals R′; and
Preferably, R′ stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl or alkoxy group having 1 to 20, preferably 1 to C atoms or a branched or cyclic alkyl or alkoxy group having 3 to 20, preferably 3 to 10 C atoms, or an aromatic or heteroaromatic ring system having 5 to 24, preferably 5 to 18 aromatic ring atoms.
Examples of suitable compounds of formula (1) are the structures shown in the table below:
The organic electroluminescent device comprises at least one emitting layer. It may also comprise further layers, for example in each case one or more hole-injection layers, hole-transport layers, hole-blocking layers, electron-transport layers, electron-injection layers, exciton-blocking layers, electron-blocking layers and/or charge-generation layers. It is likewise possible for interlayers, which have, for example, an exciton-blocking function, to be introduced between two emitting layers. However, it should be pointed out that each of these layers does not necessarily have to be present. The organic electroluminescent device here may comprise one emitting layer or a plurality of emitting layers. If a plurality of emission layers are present, these preferably have in total a plurality of emission maxima between 380 nm and 750 nm, resulting overall in white emission, i.e. various emitting compounds which are able to fluoresce or phosphoresce are used in the emitting layers. Particular preference is given to systems having three emitting layers, where the three layers exhibit blue, green and orange or red emission (for the basic structure see, for example, WO 2005/011013). These can be fluorescent or phosphorescent emission layers or hybrid systems, in which fluorescent and phosphorescent emission layers are combined with one another.
The compound according to the invention in accordance with the above-mentioned embodiments can be employed in various layers, depending on the precise structure. Preference is given to an organic electroluminescent device comprising a compound of the formula (1) or the preferred embodiments indicated above as matrix material for fluorescent or phosphorescent emitters, in particular for phosphorescent emitters, and/or in a hole-blocking layer and/or in an electron-transport layer and/or in an electron-blocking or exciton-blocking layer and/or in a hole-transport layer, depending on the precise substitution.
In a preferred embodiment of the invention, the compound of the formula (1) or the preferred embodiments indicated above is employed as matrix material for a fluorescent or phosphorescent compound, in particular for a phosphorescent compound, in an emitting layer. The organic electroluminescent device here may comprise one emitting layer or a plurality of emitting layers, where at least one emitting layer comprises at least one compound according to the invention as matrix material.
If the compound of the formula (1) or the preferred embodiments indicated above is employed as matrix material for an emitting compound in an emitting layer, it is preferably employed in combination with one or more phosphorescent materials (triplet emitters). Phosphorescence in the sense of this invention is taken to mean the luminescence from an excited state of relatively high spin multiplicity, i.e. a spin state >1, in particular from an excited triplet state. For the purposes of this application, all luminescent complexes with transition metals or lanthanides, in particular all iridium, platinum and copper complexes, are to be regarded as phosphorescent compounds.
The mixture of the compound of the formula (1) or the preferred embodiments indicated above and the emitting compound comprises between 99 and 1% by vol., preferably between 98 and 10% by vol., particularly preferably between 97 and 60% by vol., in particular between 95 and 80% by vol., of the compound of the formula (1) or the preferred embodiments indicated above, based on the entire mixture comprising emitter and matrix material. Correspondingly, the mixture comprises between 1 and 99% by vol., preferably between 2 and 90% by vol., particularly preferably between 3 and 40% by vol., in particular between 5 and 20% by vol., of the emitter, based on the entire mixture comprising emitter and matrix material.
A further preferred embodiment of the present invention is the use of the compound of the formula (1) or the preferred embodiments indicated above as matrix material for a phosphorescent emitter in combination with a further matrix material. Particularly suitable matrix materials which can be employed in combination with the compounds of the formula (1) or in accordance with the preferred embodiments are aromatic ketones, aromatic phosphine oxides or aromatic sulfoxides or sulfones, for example in accordance with WO 2004/013080, WO 2004/093207, WO 2006/005627 or WO 2010/006680, triarylamines, carbazole derivatives, for example CBP (N,N-bis-carbazolylbiphenyl) 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 in accordance with WO 2007/063754 or WO 2008/056746, indenocarbazole derivatives, for example in accordance with WO 2010/136109, WO 2011/000455, WO 2013/041176 or WO 2013/056776, azacarbazole derivatives, for example in accordance with EP 1617710, EP 1617711, EP 1731584, JP 2005/347160, bipolar matrix materials, for example in accordance with WO 2007/137725, silanes, for example in accordance with WO 005/111172, azaboroles or boronic esters, for example in accordance with WO 2006/117052, triazine derivatives, for example in accordance with WO 2007/063754, WO 2008/056746, WO 2010/015306, WO 2011/057706, WO 2011/060859 or WO 2011/060877, zinc complexes, for example in accordance with EP 652273 or WO 2009/062578, diazasilole or tetraazasilole derivatives, for example in accordance with WO 2010/054729, diazaphosphole derivatives, for example in accordance with WO 2010/054730, bridged carbazole derivatives, for example in accordance with US 2009/0136779, WO 2010/050778, WO 2011/042107, WO 2011/060867, WO 2011/088877 and WO 2012/143080, triphenylene derivatives, for example in accordance with WO 2012/048781, or debinzofuran derivatives, for example in accordance with WO 2015/169412, WO 2016/015810, WO 2016/023608, WO 2017/148564 or WO 2017/148565, or lactams, for example in accordance with WO 2011/116865 or WO 2011/137951. A further phosphorescent emitter which emits at shorter wavelength than the actual emitter may likewise be present in the mixture as co-host like, for example in WO 2010/108579.
If the compound of the formula (1) or in accordance with the preferred embodiments is employed as matrix material for an emitting compound in an emitting layer, it is preferably employed in combination with one or more phosphorescent materials (triplet emitters). Phosphorescence in the sense of this invention is taken to mean the luminescence from an excited state having spin multiplicity >1, in particular from an excited triplet state. For the purposes of this application, all luminescent transition-metal complexes and luminescent lanthanide complexes, in particular all iridium, platinum and copper complexes, are to be regarded as phosphorescent compounds.
Preferably, when the compounds of the formula (1) or in accordance with the preferred embodiments are employed as matrix materials for an emitting compound in an emitting layer, they are preferably employed in combination with one or more phosphorescent material (triplet emitters).
The mixture comprising the compound of the formula (1) or in accordance with the preferred embodiments and the emitting compound comprises between 99 and 1% by vol., preferably between 98 and 10% by vol., particularly preferably between 97 and 60% by vol., in particular between 95 and 80% by vol., of the compound of the formula (1) or in accordance with the preferred embodiments, based on the entire mixture comprising emitter and matrix material. Correspondingly, the mixture comprises between 1 and 99% by vol., preferably between 2 and 90% by vol., particularly preferably between 3 and 40% by vol., in particular between 5 and 20% by vol., of the emitter, based on the entire mixture comprising emitter and matrix material.
Suitable phosphorescent compounds (=triplet emitters) are, in particular, compounds which emit light, preferably in the visible region, on suitable excitation and in addition contain at least one atom having an atomic number greater than 20, preferably greater than 38 and less than 84, particularly preferably greater than 56 and less than 80, in particular a metal having this atomic number. The phosphorescent emitters used are preferably compounds which contain copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, in particular compounds which contain iridium or platinum. For the purposes of the present invention, all luminescent compounds which contain the above-mentioned metals are regarded as phosphorescent compounds.
Examples of the emitters described above are revealed by the 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 2014/094962, WO 2014/094961, WO 2014/094960, WO 2016/124304, WO 2016/125715, WO 2017/032439, WO 2018/011186, WO 2018/041769, WO 2019/020538, WO 2018/178001, WO 2019/115423 and W02019/158453. In general, all phosphorescent complexes as used in accordance with the prior art for phosphorescent OLEDs and as are known to the person skilled in the art in the area of organic electroluminescence are suitable, and the person skilled in the art will be able to use further phosphorescent complexes without inventive step.
Examples of suitable phosphorescent emitters are the phosphorescent emitters listed in the table below:
Suitable phosphorescent materials (=triplet emitters) that can be advantageously combined with the compounds of formula (1) are, as mentioned above, compounds which emit a red light on suitable excitation, which means phosphorescent materials having an excited triplet state level (T1) comprised between 550 and 680 nm.
In a further embodiment of the invention, the organic electroluminescent device according to the invention does not comprise a separate hole-injection layer and/or hole-transport layer and/or hole-blocking layer and/or electron-transport layer, i.e. the emitting layer is directly adjacent to the hole-injection layer or the anode, and/or the emitting layer is directly adjacent to the electron-transport layer or the electron-injection layer or the cathode, as described, for example, in WO 2005/053051. It is furthermore possible to use a metal complex which is identical or similar to the metal complex in the emitting layer as hole-transport or hole-injection material directly adjacent to the emitting layer, as described, for example, in WO 2009/030981.
It is furthermore possible to employ the compounds according to the invention in a hole-blocking or electron-transport layer. This applies, in particular, to compounds according to the invention which do not have a carbazole structure. These may preferably also be substituted by one or more further electron-transporting groups, for example benzimidazole groups.
In the further layers of the organic electroluminescent device according to the invention, it is possible to use all materials as usually employed in accordance with the prior art. The person skilled in the art will therefore be able, without inventive step, to employ all materials known for organic electroluminescent devices in combination with the compounds of the formula (1) or in accordance with the preferred embodiments.
For example, the compound according to the invention can also be used as a matrix for semiconducting light-emitting nanoparticles. In the context of the present invention, the term “nano” denotes a size in the range from 0.1 to 999 nm, preferably from 1 to 150 nm. In a preferred embodiment, the semiconducting light-emitting nano-particle is a quantum material (“Quantum sized material”). The term “quantum material” in the sense of the present invention refers to the size of the semiconductor material itself without further connections or a further surface modification, which shows the so-called quantum confinement effect, as for example in ISBN: 978-3-662-44822-9. In one embodiment of the invention, the total size of the quantum material is in the range from 1 to 100 nm, more preferably from 1 to 30 nm and particularly preferably from 5 to 15 nm. In this case, the core of the semiconducting light-emitting nano-particle can vary. Suitable examples are CdS, CdSe, CdTe, ZnS, ZnSe, ZnSeS, ZnTe, ZnO, GaAs, GaP, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InPS, InPZnS, InPZn, InPGa, InSb, AlAs , AlP, AlSb, Cu2S, Cu2Se, CuInS2, CuInSe2, Cu2(ZnSn)S4, Cu2(InGa) S4, TiO2, or a combination of said materials. In a preferred embodiment, the core of the semiconductive light-emitting particle contains one or more elements of group 13 and one or more elements of group 15 of the periodic system of the elements, for example GaAs, GaP, GaSb, InAs, InP, InPS, InPZnS, InPZn, InPGa, InSb, AlAs, AlP, AlSb, CuInS2, CuInSe2, Cu2(InGa)S4 or a combination of the mentioned materials. Particularly preferably, the core contains In- and P-atoms, z. InP, InPS, InPZnS, InPZn or InPGa. In a further embodiment of the invention, the nanoparticle contains one or more shell layers, which comprise a first element from the group 12, 13 or 14 of the periodic table and a second element from the group 15 or 16 of the periodic table. Preferably, all shell layers contain a first element from the group 12, 13 or 14 of the periodic system and a second element from the group 15 or 16 of the periodic system. In a preferred embodiment of the invention, at least one of the shell layers contains a first element from the group 12 and a second element from the group 16 of the periodic table, for example CdS, CdZnS, ZnS, ZnSe, ZnSSe, ZnSSeTe, CdS/ZnS, ZnSe/ZnS or ZnS/ZnSe. Particularly preferably, all shell layers contain a first element from the group 12 and a second element from the group 16 of the periodic table.
Preference is furthermore given to an organic electroluminescent device, characterised in that one or more layers are applied by means of a sublimation process, in which the materials are vapour-deposited in vacuum sublimation units at an initial pressure of less than 10−5 mbar, preferably less than 10−6 mbar. However, it is also possible for the initial pressure to be even lower or higher, for example less than 10−7 mbar.
Preference is furthermore given to an organic electroluminescent device, characterised in that one or more layers are applied by means of a sublimation process, in which the materials are vapour-deposited in vacuum sublimation units at an initial pressure of less than 10−5 mbar, preferably less than 10−6 mbar. However, it is also possible for the initial pressure to be even lower or higher, for example less than 10−7 mbar.
Preference is likewise given to an organic electroluminescent device, characterised in that one or more layers are applied by means of the OVPD (organic vapour phase deposition) process or with the aid of carrier-gas sublimation, in which the materials are applied at a pressure between 10−5 mbar and 1 bar. A special case of this process is the OVJP (organic vapour jet printing) process, in which the materials are applied directly through a nozzle and thus structured (for example M. S. Arnold et al., Appl. Phys. Lett. 2008, 92, 053301).
Preference is furthermore given to an organic electroluminescent device, characterised in that one or more layers are produced from solution, such as, for example, by spin coating, or by means of any desired printing process, such as, for example, ink-jet printing, LITI (light induced thermal imaging, thermal transfer printing), screen printing, flexographic printing, offset printing or nozzle printing. Soluble compounds, which are obtained, for example, by suitable substitution, are necessary for this purpose.
Also possible are hybrid processes, in which, for example, one or more layers are applied from solution and one or more further layers are applied by vapour deposition. Thus, it is possible, for example, to apply the emitting layer from solution and to apply the electron-transport layer by vapour deposition.
These processes are generally known to the person skilled in the art and can be applied by him without inventive step to organic electroluminescent devices comprising the compounds according to the invention.
The compounds according to the invention generally have very good properties on use in organic electroluminescent devices. In particular, the lifetime on use of the compounds according to the invention in organic electroluminescent devices is significantly better compared with similar compounds in accordance with the prior art. The other properties of the organic electroluminescent device, in particular the efficiency and the voltage, are likewise better or at least comparable. Furthermore, the compounds have a high glass transition temperature and high thermal stability.
The present invention furthermore relates to the compounds of the following formulae (1′),
where the following applies to the symbols and indices used:
Y stands for CRY or N; with the proviso that at least two adjacent groups Y stand for a condensed aromatic or heteroaromatic ring system with the benzothiazine ring of formula (1′);
RS, RY stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R)2, N(Ar)2, NO2, Si(R)3, B(OR)2, OSO2R, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R;
R stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R′)2, N(Ar)2, NO2, Si(R′)3, B(OR′)2, OSO2R′, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R′, where in each case one or more non-adjacent CH2 groups may be replaced by R′C═CR′, C≡C, Si(R′)2, Ge(R′)2, Sn(R′)2, C═O, C═S, C═Se, P(═O)(R′), SO, SO2, O, S or CONR′ and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R′, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R′; where two adjacent substituents R may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R′;
Ar is, on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case also be substituted by one or more radicals R′; and
R′ stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or abranched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, where in each case one or more non-adjacent CH2 groups may be replaced by SO, SO2, O, S and where one or more H atoms may be replaced by D, F, Cl, Br or I, or an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms;
characterized in that it the compounds of formulae (1′) comprise at least one radical, which stands for an aromatic or heteroaromatic ring system selected from the groups of formula (R-2),
where the dashed bond indicates the bond to the structure, and where:
ArS stands for a single bond or for an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R;
A stands, identically or differently on each occurrence, for CRA or N; or two adjacent groups A stand for a group of the formula (Ar-5) or (Ar-6),
where the dashed bonds between the signs “*” correspond to the common bond of the group of formula (Ar-5) or (Ar-6) with the group of formula (R-2), and where:
E1, E2 stands for C(R0)2, C═O, NRN, O or S;
A1 stands, identically or differently on each occurrence, for CRA1 or N;
R0, RN are on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, Si(R)3, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 24, very particularly preferably 5 to 18 aromatic ring atoms, which may be substituted by one or more radicals R, where two adjacent substituents R0 may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R;
RA, RA1 are on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R)2, N(Ar)2, NO2, Si(R)3, B(OR)2, OSO2R, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R; where two adjacent substituents RA may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two adjacent substituents RA1 may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and
n is an integer equal to 1, 2, 3 or 4.
Preferably, the compounds of formula (1′) are selected from the compound of formulae (2-1′) to (4-5′):
where the symbol RS, RY have the same meaning as above and where:
V stands for C(R0)2, NRN, O or S; preferably for NRN, O or S, more preferably for NRN;
X stands, identically or differently on each occurrence, for CRX or N; or two adjacent groups X stand for a group of the formula (Ar-3) or (Ar-4),
where the dashed bonds between the signs “*” correspond to the common bond of the group of formula (Ar-3) or (Ar-4) with the rest of the structure, and furthermore:
RX, RT stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R)2, N(Ar)2, NO2, Si(R)3, B(OR)2, OSO2R, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or a branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, Si(R)2, Ge(R)2, Sn(R)2, C═O, C═S, C═Se, P(═O)(R), SO, SO2, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R; where two adjacent substituents RT may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two adjacent substituents RX may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R;
characterized in that the compounds of formulae (2-1′) to (4-5′) comprise at least one radical RS, RX, RY, RT or R, preferably RX, RY, RT or R, which stands for a group of formula (R-2) as defined above.
More preferably, the compounds of formulae (2-1′) to (4-5′) are selected from compounds of formulae (2-1-1′) to (4-5-3′) as depicted below:
where the symbols have the same meaning as above and where the compounds of formulae (2-1-1′) to (4-5-3′) comprise at least one radical RS, RX, RY, RT or R, preferably RX, RY, RT or R, more preferably RX, RY or RT, which stands for a group of formula (R-2).
More specifically, it is preferred that the compounds of formulae (2-1-1′), (2-2-1′), (3-1-1′) and (3-2-1′) comprise at least one radical RX, RY or R, preferably one radical RX or RY, which stands for a group of formula (R-2). It is preferred that the compounds of formulae (4-1-1′), (4-2-1′), (4-2-2′), (4-3-1′), (4-3-2′), (4-4-1′), (4-4-2′), (4-5-1′) and (4-5-2′) comprise at least one radical RX or R, preferably RX, which stands for a group of formula (R-2). And it is preferred that the compounds of formulae (4-2-3′), (4-3-3′), (4-4-3′) and (4-5-3′) comprise at least one radical RX, RT or R, preferably RX or RT, which stands for a group of formula (R-2) as defined above.
The same preferences as indicated above for the compounds of the formula (1), the symbols and indices apply to the compounds of the formula (1′) according to the invention.
The compounds of the formula (1) or (1′) or the preferred embodiments can be prepared by synthetic steps known to the person skilled in the art, as depicted schematically in Scheme 1 to 8.
In schemes 1-8, the group Ar represents an aromatic or heteroaromatic ring system and the groups R and R1 represent a radical.
R and R1 may also correspond to a leaving group, preferably selected from halogens (like Cl, Br, I), boronic acid or boronic acid derivatives, triflate and tosylate. The functionalized compounds, namely the compounds substituted by a leaving group, in particular brominated compounds represent the central building block for further functionalisation. Thus, these functionalised compounds can easily be converted into compounds of the formula (1) or formula (1′) by Suzuki coupling or coupling to diarylamines by the Hartwig-Buchwald method with carbazole derivatives or triarylamine derivatives.
The brominated compounds can furthermore be lithiated and converted into ketones by reaction with electrophiles, such as benzonitrile, and subsequent acidic hydrolysis or into phosphine oxides with chlorodiphenylphosphines and subsequent oxidation.
The compounds according to the invention described above, in particular compounds which are substituted by reactive leaving groups, such as bromine, iodine, chlorine, boronic acid or boronic acid ester, or by reactive, polymerisable groups, such as olefins or oxetanes, can be used as monomers for the generation of corresponding oligomers, dendrimers or polymers. The oligomerisation or polymerisation here preferably takes place via the halogen functionality or the boronic acid functionality or via the polymerisable group. It is furthermore possible to crosslink the polymers via groups of this type. The compounds and polymers according to the invention can be employed as crosslinked or uncrosslinked layer.
Oligomers, polymers or dendrimers comprising one or more of the compounds according to the invention mentioned above, are such that one or more bonds are present from the compound according to the invention to the polymer, oligomer or dendrimer. Depending on the linking of the compound according to the invention, this therefore forms a side chain of the oligomer or polymer or is linked in the main chain. The polymers, oligomers or dendrimers may be conjugated, partially conjugated or non-conjugated. The oligomers or polymers may be linear, branched or dendritic. The same preferences as described above apply to the recurring units of the compounds according to the invention in oligomers, dendrimers and polymers.
For the preparation of the oligomers or polymers, the monomers according to the invention are homopolymerised or copolymerised with further monomers. Preference is given to homopolymers or copolymers in which the units of the formula (1), (1′) or the above-mentioned preferred embodiments are present to the extent of 0.01 to 99.9 mol %, preferably 5 to 90 mol %, particularly preferably 20 to 80 mol %. Suitable and preferred comonomers which form the polymer backbone are selected from fluorenes (for example in accordance with EP 842208 or WO 2000/22026), spirobifluorenes (for example in accordance with EP 707020, EP 894107 or WO 2006/061181), para-phenylenes (for example in accordance with WO 92/18552), carbazoles (for example in accordance with WO 2004/070772 or WO 2004/113468), thiophenes (for example in accordance with EP 1028136), dihydrophenanthrenes (for example in accordance with WO 2005/014689), cis- and trans-indenofluorenes (for example in accordance with WO 2004/041901 or WO 2004/113412), ketones (for example in accordance with WO 2005/040302), phenanthrenes (for example in accordance with WO 2005/104264 or WO 2007/017066) or also a plurality of these units. The polymers, oligomers and dendrimers may also comprise further units, for example hole-transport units, in particular those based on triarylamines, and/or electron-transport units. In addition, the polymers may comprise triplet emitters, either copolymerised or mixed in as a blend. In particular, the combination of units of the formula (1), (1′) or the above-mentioned preferred embodiments with triplet emitters results in particularly good results.
Furthermore, the compounds of the formulae (1), (1′) or the above-mentioned preferred embodiments may also be functionalised further and thus converted into extended structures. The reaction with arylboronic acids by the Suzuki method or with primary or secondary amines by the Hartwig-Buchwald method may be mentioned here as an example. Thus, the compounds of the formulae (1), (1′) or the above-mentioned preferred embodiments may also be bonded directly to phosphorescent metal complexes or also to other metal complexes.
For the processing of the compounds according to the invention from the liquid phase, for example by spin coating or by printing processes, formulations of the compounds according to the invention are necessary. These formulations can be, for example, solutions, dispersions or emulsions. It may be preferred to use mixtures of two or more solvents for this purpose. The solvents are preferably selected from organic and inorganic solvents, more preferably organic solvents. The solvents are very preferably selected from hydrocarbons, alcohols, esters, ethers, ketones and amines. 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, in particular 3-phenoxytoluene, (−)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 1-ethylnaphthalene, decylbenzene, phenyl naphthalene, menthyl isovalerate, para tolyl isobutyrate, cyclohexal hexanoate, ethyl para toluate, ethyl ortho toluate, ethyl meta toluate, decahydronaphthalene, ethyl 2-methoxybenzoate, dibutylaniline, dicyclohexylketone, isosorbide dimethyl ether, decahydronaphthalene, 2-methylbiphenyl, ethyl octanoate, octyl octanoate, diethyl sebacate, 3,3-dimethylbiphenyl, 1,4-dimethylnaphthalene, 2,2′-dimethylbiphenyl, 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 or mixtures of these solvents.
The present invention therefore furthermore relates to a formulation comprising a compound according to the invention and at least one further compound. The further compound may be, for example, a solvent, in particular one of the above-mentioned solvents or a mixture of these solvents. However, the further compound may also be at least one further organic or inorganic compound which is likewise employed in the electronic device, for example an emitting compound, in particular a phosphorescent dopant, and/or a further matrix material. Suitable emitting compounds and further matrix materials are indicated below in connection with the organic electroluminescent device. This further compound may also be polymeric.
The compounds (1′) and mixtures according to the invention are suitable for use in an electronic device. An electronic device here is taken to mean a device which comprises at least one layer which comprises at least one organic compound. However, the component here may also comprise inorganic materials or also layers built up entirely from inorganic materials.
The present invention therefore furthermore relates to the use of the compounds (1′) or mixtures according to the invention in an electronic device. Preferably, the electronic device comprising the compounds of formula (1′) is selected from the group consisting of organic electroluminescent devices, organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, dye-sensitised organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light-emitting electrochemical cells, organic laser diodes and organic plasmon emitting devices. More preferably, the electronic device comprising the compounds of formula (1′) is an organic electroluminescent device. Particularly preferably, the compound of formula (1′) is employed as a matrix material for emitters, a hole-transport-material or an electron-transport material in an organic electroluminescent device, more preferably as a matrix material for a phosphorescent emitter.
The same preferences as indicated above for an organic electroluminescent device comprising the compounds of the formula (1) apply to an organic electroluminescent device comprising the compounds of the formula (1′).
The invention will now be explained in greater detail by the following examples, without wishing to restrict it thereby.
Unless otherwise stated, the following syntheses are carried out in a protective gas atmosphere in dried solvents. The solvents and reagents can be obtained from Sigma-ALDRICH or ABCR. The CAS numbers of the compounds known from the literature are also indicated below. The compounds according to the invention can be synthesised by means of synthesis methods known to the skilled person.
a) Suzuki-Reaction
52.12 g (160 mmol) of the dibenzothiazine derivative, 50 g (172 mmol) of N-phenyl-carbazole-3-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. Afterwards, 1.8 g (1.5 mmol) of tetrakis(triphenylphosphine)-palladium(0) is added to the reaction mixture, which is then mixed for 16 h under reflux. After cooling, the organic phase is separated, filtered over silica gel, washed three times with 200 mL water and then concentrated to dryness. The yield is 51 g (96 mmol), corresponding to 60% of the theory.
The following compounds can be prepared analogously:
b) Buchwald
20.4 g (50 mmol) of 9-phenyl-3,3′-bis-9H-carbazole and 16 g (54 mmol) of 3-bromo-2-phenyl-2λ4-2,1-benzothiazine-2-oxide are dissolved in 400 ml of toluene in an argon atmosphere. Then, 1.0 g (5 mmol) of tri-tert-butyl-phosphine is added to the reaction mixture, which is stirred in an argon atmosphere. Then, 0.6 g (2 mmol) of Pd(OAc)2 is added to the reaction mixture, which is stirred in an argon atmosphere, after which 9.5 g (99 mmol) of sodium-tert-butanolate are added to the mixture. The reaction mixture is stirred under reflux for 24 hours. After cooling, the organic phase is separated, washed three times with 200 ml water, dried over MgSO4, filtered and finally, the solvent is removed under vacuum. The residue is purified by column chromatography over silica gel (eluent: DCM/Heptane (1:3)). The residue is hot extracted with toluene and recrystallized from toluene/n-heptane and finally sublimated in high vacuum. The yield is 29 g (45 mmol), corresponding to 90% of the theory.
The following compounds can be produced analogously:
c) Bromination
65 g (190 mmol) of the compound with the CAS number [2132388-80-6] are suspended in 1800 mL of DMF. Then, 34 g (190 mmol) of NBS are added portion wise to this suspension, which is stirred for 2 hours in the dark. Water/ice is then added, the solid is separated and washed with ethanol. The isomers are separated by recrystallization. The yield is 57 g (134 mmol), corresponding to 72% of the theory.
The following compounds can be produced analogously:
The use of the inventive materials in OLEDs is presented in the following examples.
Glass plates coated with structured ITO (indium tin oxide, 50 nm) are treated with an oxygen plasma followed by an argon plasma before coating. These plasma-treated glass plates form the substrates on which the OLEDs are applied.
In principle, the OLEDs have the following layer structure: substrate/optional interlayer (IL)/hole injection layer (HIL)/hole transport layer (HTL)/electron blocking layer (EBL)/emission layer (EML)/optional hole blocking layer (HBL)/electron transport layer (ETL)/optional electron injection layer (EIL) and finally a cathode. The cathode is formed by a 100 nm thick aluminium layer. The exact structure of the OLEDs is shown in Tables 1a to 1 c. The materials used for the OLED fabrication are listed in Table 2. The data of the OLEDs are listed in Tables 2a to 2c. The materials used for the fabrication of the OLEDs are listed in Table 3.
All materials are applied by thermal vapour deposition in a vacuum chamber. The emission layer here always consists of at least one matrix material (host material) and an emitting dopant (emitter), which is admixed with the matrix material or matrix materials in a certain proportion by volume by co-evaporation. An expression such as IC1:EG1:TER1 (45%:45%:10%) here means that the material IC1 is present in the layer in a proportion by volume of 45%, EG1 is present in the layer in a proportion by volume of 45% and TER1 is present in the layer in a proportion by volume of 10%. Analogously, the electron-transport layer may also consist of a mixture of two materials.
The OLEDs are characterized by standard methods. For this purpose, the electroluminescence spectra and the external quantum efficiency (EQE, measured in %) are determined as a function of luminance, calculated from current-voltage-luminance characteristics assuming a Lambertian radiation characteristic. The electroluminescence spectra are determined at a brightness of 1000 cd/m2 and the CIE 1931 x and y colour coordinates are determined. The value EQE 1000 corresponds to the external quantum efficiency at 1000 cd/m2.
In the examples E1 to E6, the inventive materials are used as matrix materials in the emission layer of green phosphorescent OLEDs.
Very good results for the external quantum efficiency are obtained for all compounds according to the invention, at operating voltages U1000 in the range of 4V.
Further inventive materials are used in the examples E7 and E9 as matrix material in the emission layer of red phosphorescent OLEDs.
Very good results for the external quantum efficiency are obtained for the three compounds in accordance with the invention, at operating voltages U1000 in the range of 4-5 V.
Further inventive materials are used in the examples E10 and E11 as ETM (Electron -transport Material) in the ETL or as HBM (Hole-Blocking Material) in the HBL of blue fluorescent OLEDs. The inventive compounds can also be used as ETM and HBM in phosphorescent OLEDs.
Very good results for the external quantum efficiency are obtained for the two compounds in accordance with the invention, at operating voltages U1000 in the range of 4-5 V.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19204493.1 | Oct 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/079444 | 10/20/2020 | WO |
