EP4185574A1

EP4185574A1 - Materials for organic electroluminescent devices

Info

Publication number: EP4185574A1
Application number: EP21743519.7A
Authority: EP
Inventors: Rouven LINGE; Miriam ENGEL; Sebastian Meyer; Sebastian Stolz
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2020-07-22
Filing date: 2021-07-19
Publication date: 2023-05-31
Also published as: TW202216952A; KR20230043106A; CN115776981A; WO2022017997A1

Abstract

The present invention relates to compounds of the formula (1) which are suitable for use in electronic devices, in particular organic electroluminescent devices, and to electronic devices which comprise these compounds.

Description

Materials for organic electroluminescent devices

The present invention relates to a compound of the formula (1 ), to the use of the compound in an electronic device, and to an electronic device com prising a compound of the formula (1). The present invention furthermore relates to a composition and to a formulation comprising one or more com pounds of the formula (1 ).

The development of functional compounds for use in electronic devices is currently the subject of intensive research. The aim is, in particular, the development of compounds with which improved properties of electronic devices in one or more relevant points can be achieved, such as, for example, power efficiency and lifetime of the device as well as colour coordinates of the emitted light.

In accordance with the present invention, the term electronic device is taken to mean, inter alia, organic integrated circuits (OICs), organic field-effect transistors (OFETs), organic thin-film transistors (OTFTs), organic light- emitting transistors (OLETs), organic solar cells (OSCs), organic optical detectors, organic photoreceptors, organic field-quench devices (OFQDs), organic light-emitting electrochemical cells (OLECs), organic laser diodes (O-lasers) and organic electroluminescent devices (OLEDs).

Of particular interest is the provision of compounds for use in the last- mentioned electronic devices called OLEDs. The general structure and the functional principle of OLEDs are known to the person skilled in the art and are described, for example, in US 4539507.

Further improvements are still necessary with respect to the performance data of OLEDs, in particular with a view to broad commercial use, for example in display devices or as light sources. Of particular importance in this connection are the lifetime, the efficiency and the operating voltage of the OLEDs and as well as the colour values achieved. In particular, in case of blue-emitting OLEDs, there is potential for improvement with respect to the efficiency, lifetime and operating voltage of the devices.

An important starting point for achieving the said improvements is the choice of the emitter compound, but also of the host material for the emitter (also called matrix material) employed in the electronic device.

Host materials for fluorescent emitters that are known from the prior art are a multiplicity of compounds. Compounds comprising at least one anthracene group and at least one dibenzofuran or dibenzothiophene group are known from the prior art (for example in KR 20170096860 and CN 109867646).

However, there is still a need for further fluorescent emitters and further host materials for fluorescent emitters, which may be employed in OLEDs and lead to OLEDs having very good properties in terms of lifetime, color emission and efficiency. More particularly, there is a need for host materials for fluorescent emitters combining very high efficiencies, very good lifetime and very good thermal stability.

Furthermore, it is known that an OLED may comprise different layers, which may be applied either by vapour deposition in a vacuum chamber or by processing from a solution. The processes based on vapour deposition lead to very good results, but they might be complex and expensive. Therefore, there is also a need for OLED materials that can be easily and reliably processed from solution. In this case, the materials should have good solubility properties in the solution that comprises them.

There is furthermore still a need for processes, which lead to stable OLED materials, which are easily purified and easily processed. There is a need for processes, which are economically and qualitatively interesting by providing OLED materials in acceptable purity and with a high yield.

The present invention is thus based on the technical object of providing compounds which are suitable for use in electronic devices, such as OLEDs, more particularly as host materials for fluorescent emitters or as fluorescent emitters, which are suitable for vacuum processing or for solution processing. The present invention is also based on the technical object of providing processes and intermediate compounds for the manufacturing of OLED materials.

In investigations on novel compounds for use in electronic devices, it has now been found, that compounds of formula (1) as defined below are eminently suitable for use in electronic devices. In particular, they achieve one or more, preferably all, of the above-mentioned technical objects.

The invention thus relates to compounds of formula (1), where the following applies to the symbols and indices used: E stands for 0 or S, preferably 0;

X stands on each occurrence, identically or differently, for CR^X or N;

Y stands on each occurrence, identically or differently, for CR^Y or N; or Y is C if Y is bonded to Ar^s, Ar¹ or Ar² or the heterocycle represented in formula (1 ) when Ar^s is absent;

Ar¹, Ar² stand on each occurrence, identically or differently, for 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;

Ar^s is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R;

R^x, R^Y stand on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(=0)Ar, P(=0)(Ar)₂, S(=0)Ar, S(=0) Ar, N(R)₂, N(Ar)₂, N0₂, Si(R)3, B(OR)₂, OS0₂R, a straight-chain alkyl, alkoxy orthioalkyl group having 1 to 40 C atoms or 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, CºC, Si(R)₂, Ge(R)₂, Sn(R)₂, C=0, C=S, C=Se, P(=0)(R), SO, S0₂, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or N0₂, 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, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R; where two radicals R^x may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two radicals R^Y may form an aliphatic, aromatic or heteroaromatic ring system together, 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(=0)Ar, P(=0)(Ar)₂, S(=0)Ar, S(=0) Ar, N(R^')₂, N(Ar)₂, N0₂, Si(R )3, B(OR^')₂, OS0₂R , a straight-chain alkyl, alkoxy orthioalkyl group having 1 to 40 C atoms or 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 , CºC, Si(R )₂, and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or N0₂, 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^', or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R^'; where two radicals 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^';

R^' stands on each occurrence, identically or differently, for FI, D, F,

Cl, Br, I, CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, where in each case one or more non-adjacent CFH₂ groups may be replaced by SO, S0₂, O, S and where one or more FI 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. n, m stand for an integer selected from 0, 1 and 2; with the proviso that n = m; p, q stand, identically or differently, for 1 , 2 or 3, preferably for 1.

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.

Furthermore, the following definitions of chemical groups apply for the purposes of the present application:

An aryl group in the sense of this invention contains 6 to 60 aromatic ring atoms, preferably 6 to 40 aromatic ring atoms, more preferably 6 to 20 aromatic ring atoms; a heteroaryl group in the sense of this invention contains 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, more preferably 5 to 20 aromatic ring atoms, at least one of which is a heteroatom. The heteroatoms 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, quino line 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, phen- anthrene, pyrene, dihydropyrene, chrysene, perylene, fluoranthene, benz anthracene, 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, naphthimi- dazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimi- dazole, oxazole, benzoxazole, naphthoxazole, anthroxazole, phenan- throxazole, 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-oxa- diazole, 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, preferably 6 to 40 C atoms, more preferably 6 to 20 C atoms. A heteroaromatic ring system in the sense of this invention contains 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, more preferably 5 to 20 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’-spirobifluo- rene, 9,9’-diarylfluorene, triarylamine, diaryl ether, stilbene, etc., are also intended to be taken to be aromatic ring systems in the sense of this inven tion, 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, naphtha- cene, pentacene, benzopyrene, biphenyl, biphenylene, terphenyl, terphenyl- ene, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene, dihydro pyrene, tetrahydropyrene, cis- or trans-indenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzo- furan, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, indolocarbazole, indenocarbazole, pyri dine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5, 6-quinoline, benzo-6, 7-quinoline, benzo-7, 8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthri- midazole, 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-diaza- pyrene, 2,3-diazapyrene, 1 ,6-diazapyrene, 1 ,8-diazapyrene, 4,5-diaza- pyrene, 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-oxadia- zole, 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 CFte 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, cyclo- heptenyl, 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, cyclooctyl- oxy, 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-heptyl- thio, cycloheptylthio, n-octylthio, cyclooctylthio, 2-ethylhexylthio, trifluoro- methylthio, pentafluoroethylthio, 2,2,2-trifluoroethylthio, ethenylthio, propenylthio, butenylthio, pentenylthio, cyclopentenylthio, hexenylthio, cyclohexenylthio, heptenylthio, cycloheptenylthio, octenylthio, cyclooctenyl- thio, ethynylthio, propynylthio, butynylthio, pentynylthio, hexynylthio, heptynylthio or octynylthio.

The formulation that two or more 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, however, 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:

When two radicals form a ring with one another, then it is preferred that the two radicals are adjacent radicals. As mentioned above, 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. In accordance with a preferred embodiment, the compounds of formula (1) are selected from the compounds of formula (2), (3), (4) or (5), formula (4) formula (5) where the symbols and indices have the same meaning as above.

In accordance with a more preferred embodiment, the compounds of formula (1) are selected from the compounds of formula (2-1), (3-1), (4-1) or (5-1 ), where the symbols and indices have the same meaning as above.

In accordance with a very more preferred embodiment, the compounds of formula (1) are selected from the compounds of formula (2-1-1) to (2-1-5), formula (2-1-1) formula (2-1-4) where the symbols and indices have the same meaning as above.

In accordance with a preferred embodiment, n = m = 0.

In accordance with another preferred embodiment, n = m = 1.

In accordance with a preferred embodiment, Ar¹ and Ar² stand on each occurrence, identically or differently, for an aromatic or heteroaromatic ring system having 5 to 40, more preferably 5 to 30, very preferably 5 to 25, particularly preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. In accordance with a very preferred embodiment, Ar¹ and Ar² stand on each occurrence, identically or differently, for phenyl, biphenyl, terphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, benzophenanthrene, benzanthracene, pyrene, perylene, triphenylene, benzopyrene, fluoranthene, dibenzofuran, dibenzothiophene, carbazole or a combination of two or three of these groups, each of which may be substituted by one or more radicals R. In accordance with a particularly preferred embodiment, Ar¹ and Ar² stand on each occurrence, identically or differently, for phenyl, biphenyl, terphenyl, fluorene, spirobifluorene, dibenzofuran, dibenzothiophene, carbazole or a combination of two or three of these groups, each of which may be substituted by one or more radicals R.

Examples of suitable groups Ar¹ and Ar² are the groups of formulae (Ar-1 ) to (Ar-9): where

- E¹ stands on each occurrence, identically or differently, for C(R°)2, NR^N, 0 or S,

- R°, R^N 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, CºC,

Si(R)₂, Ge(R)₂, Sn(R)₂, C=0, C=S, C=Se, P(=0)(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 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, 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 radicals R° may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R;

- the dashed line represents the bonding to the adjacent anthracene moiety; and

- the groups of formulae (Ar-1 ) to (Ar-9) may be substituted at each free position by a group R, where R has the same meaning as above.

The groups of formulae (Ar-1 ) to (Ar-3) are particularly preferred.

Very suitable examples of the groups Ar¹ and Ar² are the groups of formulae (Ar1 -1 ) to (Ar1 -27): where

- E¹, R°, R^N have the same meaning as above;

- the dashed line represents the bonding to the adjacent anthracene moiety; and

- the groups of formulae (Ar-1 ) to (Ar-27) may be substituted at each free position by a group R, where R has the same meaning as above. Preferably, the group Ar^s stands on each occurrence, identically or differently, for an aromatic or heteroaromatic ring system having 5 to 25, preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.

More preferably, the group Ar^s 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.

Examples of suitable groups Ar^s are the groups of formulae (ArS-1) to (ArS- 27) as represented in the table below: where the dashed bonds indicate the bonding to the adjacent groups in formula (1); where the groups of formulae (ArS-1) to (ArS-27) may be substituted at each free position by a group R, which has the same meaning as defined above; and where the group E³ is on each occurrence, identically or differently, selected from and -P(R⁰)-, where R° is as defined above. Preferably, the group E³ is identically or differently, selected from -C(R°)₂-, -0-, -S- and -N(R°)-, where R° is as defined above.

Among the groups of formulae (ArS-1) to (ArS-27), the groups of formulae (ArS-1), (ArS-2), (ArS-3), (ArS-11), (ArS-12) and (ArS-27) are preferred. The groups of formula (ArS-1), (ArS-2), (ArS-3) are very preferred. The group of formula (ArS-1) is particularly preferred. Preferably, R^x, R^Y stand on each occurrence, identically or differently, for H, D, F, CN, 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 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, CºC, O or S and where one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 6 to 18 aromatic ring atoms, which may in each case be sub stituted by one or more radicals R, where two adjacent radicals R^x may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two adjacent radicals R^Y may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R. More preferably, R^x,

R^Y stand on each occurrence, identically or differently, for H, D, F, a straight- chain alkyl group having 1 to 10 C atoms or branched or a cyclic alkyl group having 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more FI atoms may be replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 30, preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where two adjacent radicals R^x may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two adjacent radicals R^Y may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R.

Preferably, R stands on each occurrence, identically or differently, for FI, D,

F, CN, 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 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^', CºC, O or S and where one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 6 to 18 aromatic ring atoms, which may in each case be sub stituted 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 5 to 30, more preferably 6 to 18 aromatic ring atoms, which may in each case be sub stituted by one or more radicals R^'.

Preferably, R^’ stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 10 C atoms, where in each case one or more FI atoms may be replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 18 C atoms.

The following compounds are examples of compounds of formula (1 ):

The compounds according to the invention can be prepared by synthesis steps known to the person skilled in the art, such as, for example, bromina- tion, Suzuki coupling, Ullmann coupling, Hartwig-Buchwald coupling, etc. An example of a suitable synthesis process is depicted in general terms in schemes 1 and 6 below.

Scheme 1 Where, in Scheme 1 :

X¹ and X², identical or different, leaving groups, preferably selected from the group consisting of halogen atoms, triflates and boronic acid derivatives. Anth corresponds to an anthracene group;

Ar¹ and Ar² have the same definition as above.

Scheme 2

Where, in Scheme 2:

X¹ and X² are different leaving groups, preferably selected from the group consisting of halogen atoms, triflates and boronic acid derivative. More preferably, X¹ is a triflate and X² is a halogen;

Anth corresponds to an anthracene group;

Ar¹ and Ar² have the same definition as above.

The structures depicted in Schemes 1 and 2 may be further substituted at any free positions.

A further subject of the present application is thus a process for preparation of a compound according to formula (1 ), characterized in that it comprises a coupling reaction, preferably Suzuki coupling reaction, of a dibenzofuran carrying two reactive groups with an anthracene derivative.

For the processing of the compounds according to the invention from the liquid phase, for example by spin coating or by printing processes, formu lations 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-tetra- methylbenzene, 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, a-terpineol, benzothiazole, butyl benzoate, cumene, cyclohexanol, cyclo hexanone, 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, di ethylene glycol monobutyl ether, tripropylene glycol dimethyl ether, tetra- ethylene 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 com prising a compound according to the invention and at least one further compound. The further compound may be, for example, a solvent, in parti cular one of the above-mentioned solvents or a mixture of these solvents. Flowever, the further compound may also be at least one further organic or inorganic compound which is likewise employed in the electronic device, for example a phosphorescent dopant, a fluorescent dopant, a TADF dopant and/or a host material. Suitable compounds are indicated below in connection with the organic electroluminescent device. This further compound may also be polymeric. Preferably, the formulation comprises a compound of formula (1) and at least one solvent. More preferably, the formulation comprises a compound of formula (1), an emitting material selected from fluorescent emitters, TADF emitters and phosphorescent emitters and at least one solvent. Even more preferably, the formulation comprises a compound of formula (1), an emitting material selected from fluorescent emitters, TADF emitters and phosphorescent emitters, a further host material and at least one solvent.

The compounds 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. Flowever, 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 com pounds or mixtures according to the invention in an electronic device, in particular in an organic electroluminescent device.

The present invention again furthermore relates to an electronic device comprising at least one of the compounds or mixtures according to the invention mentioned above. The preferences stated above for the com pound also apply to the electronic devices.

The electronic device is preferably selected from the group consisting of organic electroluminescent devices (OLEDs, PLEDs), organic integrated circuits (O-ICs), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic dye-sensitised solar cells, 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" (D. M. Koller etal., Nature Photonics 2008, 1-4), preferably organic electroluminescent devices (OLEDs, PLEDs), in particular phosphorescent OLEDs.

The organic electroluminescent device comprises a cathode, an 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-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 plu rality of emitting layers. If a plurality of emission layers is 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 embodi ments indicated above can be employed in various layers, depending on the precise structure and on the substitution. Preference is given to an organic electroluminescent device comprising a compound of the formula (1) or in accordance with the preferred embodiments as fluorescent emitters, as emitters showing TADF (Thermally Activated Delayed Fluorescence), or as a host material for a dopant selected from emitting materials.

Particularly preferred is an organic electroluminescent device comprising a compound of the formula (1 ) or in accordance with the preferred embodiments as a host material for fluorescent emitters, more particularly for blue-emitting fluorescent emitters. The compounds of formula (1) can also be employed 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. The preferred embodiments indicated above also apply to the use of the materials in organic electronic devices.

The compound according to the invention is particularly suitable for use as a host material for a fluorescent emitting compound. The terms host materials and matrix materials can be used synonymously.

A host material here is taken to mean a material which is present in the emitting layer, preferably as the principal component, and which does not emit light on operation of the device.

The proportion of the emitting compound in the mixture of the emitting layer is between 0.1 and 50.0%, preferably between 0.5 and 20.0%, particularly preferably between 1.0 and 10.0%. Correspondingly, the proportion of the host material or host materials is between 50.0 and 99.9%, preferably between 80.0 and 99.5%, particularly preferably between 90.0 and 99.0%.

The specifications of the proportions in % are, for the purposes of the pre sent application, taken to mean % by vol. if the compounds are applied from the gas phase and % by weight if the compounds are applied from solution.

If the compound according to the invention is employed as a host material for a fluorescent emitting compound in an emitting layer, it may be employed in combination with one or more fluorescent emitting compounds. Preferred fluorescent emitters are aromatic anthracenamines, aromatic anthracenediamines, aromatic pyrenamines, aromatic pyrenediamines, aromatic chrysenamines or aromatic chrysenediamines. An aromatic anthracenamine is taken to mean a compound in which one diarylamino group is bonded directly to an anthracene group, preferably in the 9-position. An aromatic anthracenediamine is taken to mean a compound in which two diarylamino groups are bonded directly to an anthracene group, preferably in the 9,10-position. Aromatic pyrenamines, pyrenediamines, chrysenamines and chrysenediamines are defined analogously thereto, where the diarylamino groups are preferably bonded to the pyrene in the 1 -position or in the 1,6-position. Further preferred emitters are indenofluorenamines or indenofluorenediamines, for example in accordance with WO 2006/108497 or WO 2006/122630, benzoindenofluorenamines or benzoindenofluorene- diamines, for example in accordance with WO 2008/006449, and dibenzo- indenofluorenamines or dibenzoindenofluorenediamines, for example in accordance with WO 2007/140847, and the indenofluorene derivatives containing condensed aryl groups which are disclosed in WO 2010/012328. Still further preferred emitters are benzanthracene derivatives as disclosed in WO 2015/158409, anthracene derivatives as disclosed in WO 2017/036573, fluorene dimers connected via heteroaryl groups like in WO 2016/150544 or phenoxazine derivatives as disclosed in WO 2017/028940 and WO 2017/028941. Preference is likewise given to the pyrenarylamines disclosed in WO 2012/048780 and WO 2013/185871. Preference is likewise given to the benzoindenofluorenamines disclosed in WO 2014/037077, the benzofluorenamines disclosed in WO 2014/106522 and the indenofluorenes disclosed in WO 2014/111269 or WO 2017/036574, WO 2018/007421. Also preferred are the emitters comprising dibenzofuran or indenodibenzofuran moieties as disclosed in WO 2018/095888, WO 2018/095940, WO 2019/076789, WO 2019/170572 as well as in the unpublished applications PCT/EP2019/072697, PCT/EP2019/072670 and PCT/EP2019/072662. Preference is likewise given to boron derivatives as disclosed, for example, in WO 2015/102118, CN 108409769, CN 107266484, WO2017195669, US2018069182 as well as in the unpublished applications EP 19168728.4, EP 19199326.0 and EP 19208643.7.

Examples of suitable fluorescent emitting compounds to be used in combination for the compound of formula (1) are depicted in the following

The electronic device concerned may comprise a single emitting layer comprising the compound according to the invention or it may comprise two or more emitting layers. The further emitting layers here may comprise one or more compounds according to the invention or alternatively other compounds.

If the compound according to the invention is employed as a host material for a fluorescent emitting compound in an emitting layer, it may be employed in combination with one or more further host materials.

Preferred host materials for use in combination with the compound of formula (1) or its preferred embodiments are selected from the classes of the oligoarylenes (for example 2,2‘,7,7‘-tetraphenylspirobifluorene in accor dance with EP 676461 or dinaphthylanthracene), in particular the oligo arylenes containing condensed aromatic groups, the oligoarylenevinylenes (for example DPVBi or spiro-DPVBi in accordance with EP 676461), the polypodal metal complexes (for example in accordance with WO 2004/ 081017), the hole-conducting compounds (for example in accordance with WO 2004/058911), the electron-conducting compounds, in particular ketones, phosphine oxides, sulfoxides, etc. (for example in accordance with WO 2005/084081 and WO 2005/084082), the atropisomers (for example in accordance with WO 2006/048268), the boronic acid derivatives (for example in accordance with WO 2006/117052), the benzanthracenes (for example in accordance with WO 2008/145239) or the phenanthrenes (for example in accordance with W02009/100925). Particularly preferred host materials are selected from the classes of the oligoarylenes, comprising naphthalene, anthracene, benzanthracene and/or pyrene or atropisomers of these compounds, the oligoarylenevinylenes, the ketones, the phosphine oxides and the sulfoxides. Very particularly preferred host materials are selected from the classes of the oligoarylenes, comprising anthracene, benzanthracene, benzophenanthrene and/or pyrene or atropisomers of these compounds. An oligoarylene in the sense of this invention is intended to be taken to mean a compound in which at least three aryl or arylene groups are bonded to one another.

Particularly preferred host materials for use in combination with the com pounds of the formula (1 ) in the emitting layer are depicted in the following table.

On the other hand, the compounds according to the invention can also be employed as fluorescent emitting compounds. In this case, the suitable host materials for the compound of formula (1) used as a fluorescent emitting compound correspond to further compounds of formula (1 ) or to the preferred host materials described above.

The compounds according to the invention can also be employed in other layers, for example as hole-transport materials in a hole-injection or hole- transport layer or electron-blocking layer or as host materials in an emitting layer, preferably as host materials for phosphorescent emitters. If the compound of the formula (1 ) is employed as hole-transport material in a hole-transport layer, a hole-injection layer or an electron-blocking layer, the compound can be employed as pure material, i.e. in a proportion of 100%, in the hole-transport layer, or it can be employed in combination with one or more further compounds. According to a preferred embodiment, the organic layer comprising the compound of the formula (I) then additionally comprises one or more p-dopants. The p-dopants employed in accordance with the present invention are preferably organic electron-acceptor compounds which are able to oxidise one or more of the other compounds of the mixture.

Particularly preferred embodiments of p-dopants are the compounds dis closed in WO 2011/073149, EP 1968131, EP 2276085, EP 2213662,

EP 1722602, EP 2045848, DE 102007031220, US 8044390, US 8057712, WO 2009/003455, WO 2010/094378, WO 2011/120709, US 2010/0096600 and WO 2012/095143.

The compounds of formula (1) is preferably employed as host material in combination with a fluorescent material. However, the compounds of formula (1) may also be employed as host material in combination with a phosphorescent emitter in an emitting layer. In this case, the phosphores cent emitter is preferably selected from the classes and embodiments of phosphorescent emitters indicated below. Furthermore, one or more further host materials are preferably present in the emitting layer in this case. So- called mixed-matrix systems or mixed-host systems of this type preferably comprise two or three different host materials, particularly preferably two different host materials. It is preferred here for one of the two materials to be a material having hole-transporting properties and for the other material to be a material having electron-transporting properties. The compound of the formula (1) is preferably the material having hole-transporting properties. However, the desired electron-transporting and hole-transporting properties of the mixed-host components may also be combined mainly or completely in a single mixed-host component, where the further mixed-host component or components satisfy other functions. The two different host materials may be present here in a ratio of 1 : 50 to 1 :1 , preferably 1 :20 to 1 :1 , particularly preferably 1 : 10 to 1 :1 and very particularly preferably 1 :4 to 1 :1. Further details on mixed-host systems are contained, inter alia, in the application WO 2010/108579.

Particularly suitable host materials which can be used as host components of a mixed-host system in combination with the compounds according to the invention are selected from the preferred host materials for phosphorescent emitters indicated below or the preferred host materials for fluorescent emitters, depending on what type of emitter compound is employed in the mixed-host system.

Suitable phosphorescent 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, pref erably greater than 38 and less than 84, particularly preferably greater than 56 and less than 80. The phosphorescent emitters used are preferably com pounds which contain copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, in particular compounds which contain iridium, platinum or copper.

For the purposes of the present invention, all luminescent iridium, platinum or copper complexes are regarded as phosphorescent compounds.

Examples of the phosphorescent emitters described above are revealed by the applications WO 2000/70655, WO 2001/41512, WO 2002/02714,

WO 2002/15645, EP 1191613, EP 1191612, EP 1191614, WO 2005/ 033244, WO 2005/019373 and US 2005/0258742. In general, all phospho rescent complexes as used in accordance with the prior art for phosphores cent OLEDs and as are known to the person skilled in the art in the area of organic electroluminescent devices are suitable for use in the devices according to the invention. The person skilled in the art will also be able to employ further phosphorescent complexes without inventive step in combi nation with the compounds according to the invention in OLEDs.

Preferred matrix materials for phosphorescent emitters 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-biscarbazolylbiphenyl) or the carbazole derivatives disclosed in WO 2005/039246, US 2005/0069729, JP 2004/288381, EP 1205527 or WO 2008/086851, 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 or WO 2013/041176, 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 2005/111172, azaboroles or boronic esters, for example in accordance with WO 2006/117052, triazine derivatives, for example in accordance with WO 2010/015306, WO 2007/063754 or WO 2008/056746, zinc complexes, for example in accor dance with EP 652273 or WO 2009/062578, diazasilole or tetraazasilole derivatives, for example in accordance with WO 2010/054729, diazaphos- phole 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 2011/088877 or WO 2012/ 143080, triphenylene derivatives, for example in accordance with WO 2012/048781, or lactams, for example in accordance with WO 2011/116865 or WO 2011/137951.

Besides the compounds according to the invention, suitable charge-trans- port materials, as can be used in the hole-injection or hole-transport layer or electron-blocking layer or in the electron-transport layer of the electronic device according to the invention, are, for example, the compounds dis closed in Y. Shirota et al. , Chem. Rev. 2007, 107(4), 953-1010, or other materials as are employed in these layers in accordance with the prior art.

Materials which can be used for the electron-transport layer are all materials as are used in accordance with the prior art as electron-transport materials in the electron-transport layer. Particularly suitable are aluminium complexes, for example Alq3, zirconium complexes, for example Zrq4, lith ium complexes, for example LiQ, benzimidazole derivatives, triazine deriva tives, pyrimidine derivatives, pyridine derivatives, pyrazine derivatives, quin- oxaline derivatives, quinoline derivatives, oxadiazole derivatives, aromatic ketones, lactams, boranes, diazaphosphole derivatives and phosphine oxide derivatives. Furthermore, suitable materials are derivatives of the above- mentioned compounds, as disclosed in JP 2000/053957, WO 2003/060956, WO 2004/028217, WO 2004/080975 and WO 2010/072300.

Preferred hole-transport materials which can be used in a hole-transport, hole-injection or electron-blocking layer in the electroluminescent device according to the invention are indenofluorenamine derivatives (for example in accordance with WO 06/122630 or WO 06/100896), the amine derivatives disclosed in EP 1661888, hexaazatriphenylene derivatives (for example in accordance with WO 01/049806), amine derivatives containing condensed aromatic rings (for example in accordance with US 5,061 ,569), the amine derivatives disclosed in WO 95/09147, monobenzoindenofluorenamines (for example in accordance with WO 08/006449), dibenzoindenofluorenamines (for example in accordance with WO 07/140847), spirobifluorenamines (for example in accordance with WO 2012/034627 or WO 2013/120577), fluorenamines (for example in accordance with the as applications EP 2875092, EP 2875699 and EP 2875004), spirodibenzopyranamines (for example in accordance with WO 2013/083216) and dihydroacridine derivatives (for example in accordance with WO 2012/150001). The compounds according to the invention can also be used as hole-transport materials.

The cathode of the organic electroluminescent device preferably comprises metals having a low work function, metal alloys or multilayered structures comprising various metals, such as, for example, alkaline-earth metals, alkali metals, main-group metals or lanthanoids (for example Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.). Also suitable are alloys comprising an alkali metal or alkaline-earth metal and silver, for example an alloy comprising magnesium and silver. In the case of multilayered structures, further metals which have a relatively high work function, such as, for example, Ag or Al, can also be used in addition to the said metals, in which case combinations of the metals, such as, for example, Ca/Ag, Mg/Ag or Ag/Ag, are generally used. It may also be preferred to introduce a thin interlayer of a material having a high dielectric constant between a metallic cathode and the organic semiconductor. Suitable for this purpose are, for example, alkali metal fluorides or alkaline-earth metal fluorides, but also the corresponding oxides or carbonates (for example LiF, U2O, BaF2, MgO, NaF, CsF, CS2CO3, etc.). Furthermore, lithium quinolinate (LiQ) can be used for this purpose. The layer thickness of this layer is preferably between 0.5 and 5 nm.

The anode preferably comprises materials having a high work function. The anode preferably has a work function of greater than 4.5 eV vs. vacuum. Suitable for this purpose are on the one hand metals having a high redox potential, such as, for example, Ag, Pt or Au. On the other hand, metal/metal oxide electrodes (for example AI/Ni/NiOx, Al/PtOx) may also be preferred.

For some applications, at least one of the electrodes must be transparent or partially transparent in order to facilitate either irradiation of the organic material (organic solar cells) or the coupling-out of light (OLEDs, O-lasers). Preferred anode materials here are conductive mixed metal oxides.

Particular preference is given to indium tin oxide (ITO) or indium zinc oxide (IZO). Preference is furthermore given to conductive, doped organic materials, in particular conductive doped polymers.

The device is appropriately (depending on the application) structured, pro vided with contacts and finally sealed, since the lifetime of the devices according to the invention is shortened in the presence of water and/or air.

In a preferred embodiment, the organic electroluminescent device according to the invention is characterised in that one or more layers are coated by means of a sublimation process, in which the materials are applied by vapour deposition in vacuum sublimation units at an initial pressure of less than 10⁵ mbar, preferably less than 10⁶ mbar. However, it is also possible here for the initial pressure to be even lower, for example less than 10⁷ mbar.

Preference is likewise given to an organic electroluminescent device, char acterised in that one or more layers are coated 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 of between 10⁵ 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 are thus structured (for example M. S. Arnold etal., 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 proc ess, such as, for example, screen printing, flexographic printing, nozzle printing or offset printing, but particularly preferably LITI (light induced thermal imaging, thermal transfer printing) or ink-jet printing. Soluble com pounds of the formula (I) are necessary for this purpose. High solubility can be achieved through suitable substitution of the compounds. 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.

In accordance with the invention, the electronic devices comprising one or more compounds according to the invention can be employed in displays, as light sources in lighting applications and as light sources in medical and/or cosmetic applications (for example light therapy).

The invention will now be explained in greater detail by the following examples, without wishing to restrict it thereby.

A) Syntheses examples

Synthesis of compound A1 :

15 g (38 mmol) Trifluoro-methanesulfonic acid 8-bromo-dibenzofuran-1-yl ester, 43.3 g (114 mmol) 4,4,5,5-Tetramethyl-2-(10-phenyl-anthracen-9-yl)- [1 ,3,2]dioxaborolane, 35.5 g ( 167 mmol) potassium phosphate and 1.6 g (1 ,9 mmol) XPhos Palladacycle Gen. 3 are dissolved in 450 ml THF/water (2:1). The mixture is stirred at 90°C for 16 hours. After cooling down to room temperature 300 ml ethanol is added and the mixture is stirred for one hour. The precipitate is filtered off and washed with ethanol. The raw material is dissolved in toluene and filtered through a filter plug (silica, toluene) to give a yellow solid, which is further purified by several crystallizations out of toluene/heptane to give a pale yellow solid (HPLC >99.9). The remaining solvents are removed by sublimation (10^_5 bar at 330°C).

Yield: 15.2 g (22.6 mmol; 60%)

Following compounds can be synthesized in analogous manner:

Synthesis of compound B1 :

First step - Synthesis of the intermediate

10 g (25.3 mmol) Trifluoro-methanesulfonic acid 8-bromo-dibenzofuran-1-yl ester, 11.5 g (25.31 mmol) 4,4,5,5-tetramethyl-2-[3-(10-phenylanthracen-9- yl)phenyl]-1 ,3,2-dioxaborolane, 7.7 g (55.7 mmol) potassium carbonate,

1.16 g (1.3 mmol) tris(dibenzyliden-aceton)dipalladium and 324 mg (0.76 mmol) 1 ,4-bis(diphenylphosphino)butane are dissolved in 250 ml THF/water (4:1). The mixture is stirred at 100°C for 16 hours. After cooling down to room temperature 100 ml toluene and 100 ml water added and the two phases are separated. The organic phase is washed two times with water and the combined aqueous phases are extracted 2 times with toluene. The combined organic phases are filtered through a silica plug using toluene as eluent and reduced under reduced pressure. The residue is purified by several recrystalisations from toluene/heptane to give a pale yellow solid (HPLC >98).

Yield: 6.3 g (11 mmol; 43%)

Following compounds can be synthesized in analogous manner:

Second step - Synthesis of the product

10 g (17.4 mmol) compound 11 , 8.3 g (18.5 mmol) 952604-31-8, 8.1 g (38.3 mmol) potassium phosphate and 0.8 g (1 mmol) XPhos Palladacycle Gen. 3 are dissolved in 450 ml THF/water (2:1). The mixture is stirred at 90°C for 16 hours. After cooling down to room temperature 300 ml ethanol is added and the mixture is stirred for one hour. The precipitate is filtered off and washed with ethanol. The raw material is dissolved in toluene and filtered through a filter plug (silica, toluene) to give a yellow solid, which is further purified by several crystallizations out of toluene/heptane to give a pale yellow solid (HPLC >99.9). The remaining solvents are removed by sublimation (10^_5 bar at 330°C).

Yield: 8.2 g (9.1 mmol, 52%)

Following compounds can be synthesized in analogous manner: B) Fabrication of OLEDs

The production of solution-based OLEDs has already been described many times in the literature, for example in WO 2004/037887 and WO 2010/097155. The process is adapted to the circumstances described below (layer-thickness variation, materials).

The inventive material combinations are used in the following layer sequence:

- substrate,

- ITO (50 nm),

- Hole injection layer (20 nm),

- hole transport layer (25 nm),

- emission layer (EML) (30 nm),

- electron-blocking layer (HBL) (10 nm),

- electron-transport layer (ETL) (40 nm),

- cathode (Al) (100 nm).

Glass plates coated with structured ITO (indium tin oxide) in a thickness of 50 nm serve as substrate. These are coated with the buffer (PEDOT:PSS) Clevios P VP Al 4083 (Heraeus Clevios GmbH, Leverkusen). The spin coating of the buffer is carried out from water in air. The layer is subse quently dried by heating at 180°C for 10 minutes. The hole transport layers and the emission layers are applied to the glass plates coated in this way.

The hole-transport layer is either the polymer of the structure shown in table 1 (HTM1), which is synthesized in accordance with W02013156130 or the polymer HTM2 (table 1), which is synthesized in accordance with WO201 8/114882. The polymer is dissolved in toluene, so that the solution typically has a solid content of approx. 6 g/l if, as here, the layer thickness of 25 nm which is typical for a device is to be achieved by means of spin coating. The layers are applied by spin coating in an inert-gas atmosphere, in the present case argon, and dried by heating at 225°C for 30 min.

The emission layer is composed of the matrix material (host material) H and the emitting dopant (emitter) D. Both materials are present in the emission layer in a proportion of 98 % by weight H and 2 % by weight D. The mixture for the emission layer is dissolved in toluene. The solids content of such solutions is about 10 mg/ml if, as here, the layer thickness of 30 nm which is typical for a device is to be achieved by means of spin coating. The layers are applied by spin coating in an inert-gas atmosphere, and dried by heating at 145°C for 15 minutes. The materials used in the present case are shown in table 1.

The materials for the electron-blocking layer and the electron-transporting layer are likewise applied by thermal vapour deposition in a vacuum chamber and are shown in table 2. The electron-blocking layer consists of the material ETM1 and the electron-transporting layer consists of the two materials ETM1 and ETM2, which are mixed with one another in a proportion by volume of 55% of ETM1 and 45% of ETM2 by co-evaporation. The cathode is formed by the thermal evaporation of an aluminium layer with a thickness of 100 nm. The OLEDs are characterised by standard methods. For this purpose, the electroluminescence spectra are recorded, the current efficiency (measured in cd/A) and the external quantum efficiency (EQE, measured in percent) as a function of the luminous density assuming Lambert emission characteristics are calculated from current/voltage/luminous density characteristic lines (IUL characteristic lines). The electroluminescence spectra are recorded at a luminous density of 500 cd/m², and the CIE 1931 x and y colour coordinates are calculated from this data. The lifetime LT80 @ 500 cd/m² is defined as the time after which the initial luminous density of 500 cd/m² has dropped by 20%.

Use of inventive compounds as emitting material in fluorescent OLEDs

The inventive compounds are especially suitable as host when blended with a fluorescent blue dopant to form the emissive layer of a fluorescent blue OLED device. The representative examples are H1, H2, H3 and H4. The properties of the various OLEDs are summarised in table 3. Examples V1 and V2 represent the prior art, whereas examples E1 , E2, E3, E4 and E5 show properties of OLEDs containing materials of the present invention.

Table 3 shows that the use of the host materials H 1 , H2, H3 and H4 according to the present invention give rise in lifetime while keeping the efficiency and color similar over the prior art (HR) when used as matrix materials in fluorescent blue OLEDs.

Claims

Patent Claims

1. Compound of the formula (1 ), where the following applies to the symbols and indices used:

E stands for O or S;

X stands on each occurrence, identically or differently, for CR^X or N;

Ar¹, Ar² stand on each occurrence, identically or differently, for 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; Ar^s is on each occurrence, identically or differently, an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R;

R^x, R^Y stand on each occurrence, identically or differently, for H, D, F, Cl,

Br, I, CHO, CN, C(=0)Ar, P(=0)(Ar)₂, S(=0)Ar, S(=0) Ar, N(R)₂, N(Ar)₂,

N0₂, Si(R)3, B(OR)₂, 0S0₂R, a straight-chain alkyl, alkoxy orthioalkyl group having 1 to 40 C atoms or 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, CºC, Si(R)₂, Ge(R)₂, Sn(R)₂,

C=0, C=S, C=Se, P(=0)(R), SO, S0₂, O, S or CONR and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or N0₂, 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, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R; where two radicals R^x may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R; and where two radicals R^Y may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R;

R stands on each occurrence, identically or differently, for FI, D, F, Cl, Br, I, CHO, CN, C(=0)Ar, P(=0)(Ar)₂, S(=0)Ar, S(=0)₂Ar, N(R^')₂, N(Ar)₂, N0₂,

Si(R )3, B(OR^')₂, OS0₂R , a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or 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 group may be replaced by R C=CR , CºC, Si(R^')₂, Ge(R^')₂, Sn(R^')₂, C=0, C=S, C=Se, P(=0)(R ), SO, S0₂, 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 system having 5 to 60 aromatic ring atoms, which may in each case be sub stituted 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 radicals R may form an aliphatic or aromatic ring system together, 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, CN, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atoms or branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms, where in each case one or more non-adjacent CFI2 groups may be replaced by SO, SO2, O, S and where one or more FI 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. n, m stand for an integer selected from 0, 1 and 2; with the proviso that n = m; p, q stand, identically or differently, for an integer selected from 1 , 2 or 3.

2. Compound according to claim 1 , characterized in that it is selected from compounds of formula (2), (3), (4) or (5), where the symbols and indices have the same meaning as in claim 1.

3. Compound according to claim 1 or 2, characterized in that it is selected from compounds of formula (2-1 ), (3-1 ), (4-1 ) or (5-1 ), where the symbols and indices have the same meaning as in claim 1.

4. Compound according to one or more of the preceding claims, characterized in that n = m = 0 or n = m = 1.

5. Compound according to one or more of the preceding claims, characterized in that Ar¹ and Ar² stand on each occurrence, identically or differently, for phenyl, biphenyl, terphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, benzophenanthrene, benzanthracene, pyrene, perylene, triphenylene, benzopyrene, fluoranthene, dibenzofuran, dibenzothiophene, carbazole or a combination of two or three of these groups, each of which may be substituted by one or more radicals R.

6. Compound according to one or more of the preceding claims, characterized in that Ar¹ and Ar² stand on each occurrence, identically or differently, for a group of one of the formulae (Ar-1 ) to (Ar-9): where

- E¹ stands on each occurrence, identically or differently, for C(R°)2, NR^N, O or S,

- R°, R^N 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, CºC, Si(R)₂, Ge(R)₂, Sn(R)₂, C=0, C=S, C=Se, P(=0)(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 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, 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 radicals R° may form an aliphatic, aromatic or heteroaromatic ring system together, which may be substituted by one or more radicals R;

- the dashed line represents the bonding to the adjacent anthracene moiety; and

- the groups of formulae (Ar-1 ) to (Ar-9) may be substituted at each free position by a group R, which has the same meaning as in claim 1.

7. Composition comprising a compound according to one or more of the claims 1 to 6 as a host material and a dopant selected from emitting materials.

8. Composition according to claim 7, characterized in that it comprises a second host material.

9. Formulation comprising a compound according to one or more of the claims 1 to 6 and at least one solvent.

10. Formulation according to claim 9, characterized in that it comprises a further compound, which is selected from emitting materials.

11. Formulation according to claim 9 or 10, characterized in that it comprises a further compound, which is selected from host materials.

12. Electronic device comprising at least one compound according to one or more of claims 1 to 6, 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.

13. Electronic device according to claim 12, which is an organic electrolumi nescent device, characterised in that the compound according to one or more of claims 1 to 6 is employed as a host material in an emitting layer, wherein the emitting layer comprises at least one fluorescent emitter.

14. Organic electroluminescent device according to claim 13, characterised in that the emitting layer further comprises at least one further component selected from host materials.