organic electroluminescent devices

Abstract

The present invention relates to an organic electroluminescent device comprising a mixture of an electron-transporting host material and a hole-transporting host material, and to a formulation comprising the mixture of host materials and a mixture comprising the host materials. The electron-transporting host material corresponds to a compound of formula (1) from the class of compounds containing a bisspirofluorenyl unit.

Description

[0001] The present invention relates to an organic electroluminescent device comprising a mixture of an electron-transporting host material and a hole-transporting host material, and to a formulation comprising the mixture of host materials and a mixture comprising the host materials. The electron-transporting host material corresponds to a compound of formula (1) from the class of compounds containing a bisspirofluorenyl unit.

[0002] The structure of organic electroluminescent devices (e.g., OLEDs—organic light-emitting diodes) or OLECs—organic light-emitting electrochemical cells) using organic semiconductors as functional materials has long been known. In addition to fluorescent emitters, the emitting materials used here are increasingly organometallic complexes that exhibit phosphorescence rather than fluorescence. For quantum mechanical reasons, the use of organometallic compounds as phosphorescent emitters can increase energy and power efficiency by up to a factor of four. However, in general, OLEDs, especially those exhibiting triplet emission (phosphorescence), still require improvement, for example in terms of efficiency, operating voltage, and lifetime.

[0003] The properties of organic electroluminescent devices depend not only on the luminophore used. In particular, the other materials used, such as host and matrix materials, hole-blocking materials, electron-transporting materials, hole-transporting materials, and electron- or exciton-blocking materials, and especially the host or matrix materials, are also particularly important. Improvements in these materials can lead to significant improvements in electroluminescent devices.

[0004] Host materials used in organic electronic devices are well known to those skilled in the art. The term "host material" is also often used in the prior art to refer to the host material of a phosphorescent emitter. This use of the term also applies to the present invention. Meanwhile, a variety of host materials have been developed for use in fluorescent and phosphorescent electronic devices.

[0005] Another way to improve the performance data of electronic devices, in particular organic electroluminescent devices, is to use combinations of two or more materials, in particular host materials or matrix materials.

[0006] US Pat. No. 6,392,250 B1 discloses using a mixture of an electron-transporting material, a hole-transporting material, and a fluorescent emitter in the light-emitting layer of an OLED. With the aid of this mixture, the lifetime of the OLED can be increased compared to the prior art.

[0007] US Pat. No. 6,803,720 B1 discloses the use of a mixture comprising a phosphorescent emitter and a hole-transporting material and an electron-transporting material in the light-emitting layer of an OLED. The hole-transporting material and the electron-transporting material are both small organic molecules.

[0008] WO 2011088877 describes specific heterocyclic compounds that can be used as light-emitting compounds or host materials or hole-transporting materials in organic light-emitting devices.

[0009] According to WO 2015169412, triazine-dibenzofuran-aryl derivatives and triazine-dibenzothiophene-aryl derivatives can be used as host materials, for example, in the light-emitting layer.

[0010] KR 20170113318 describes specific heterocyclic compounds that can be used as host materials in the light-emitting layer of an organic light-emitting device.

[0011] According to US 20180337348, triazine-dibenzofuran-aryl derivatives and triazine-dibenzothiophene-aryl derivatives can be used, for example, in a mixture with a specific biscarbazole. For comparison purposes, the following compounds were used in a single host system:

[0012]

[0013] US 2019013490 describes specific dibenzofuran compounds or dibenzothiophene compounds, and their use as host materials in combination with other host materials.

[0014] US 2019047991 describes disubstituted triazine-dibenzofuran derivatives and their use as organic materials in organic light-emitting devices.

[0015] WO 19031679 describes an organic light-emitting device containing a disubstituted triazine-dibenzofuran derivative as a host material and a secondary host material in the light-emitting layer.

[0016] However, there is still a need for improvements in the use of these materials or mixtures of said materials, in particular with regard to the efficiency, the operating voltage and / or the lifetime of organic electroluminescent devices.

[0017] The problem addressed by the present invention is therefore to provide a host material combination which is suitable for organic electroluminescent devices, in particular for fluorescent or phosphorescent OLEDs, and which leads to good device performance, in particular with regard to improved lifetime, and to provide corresponding electroluminescent devices.

[0018] It has now been found that this problem is solved and the disadvantages of the prior art are eliminated by combining at least one compound of formula (1) as a first host material and at least one hole transport compound of formula (2) as a second host material in the light-emitting layer of an organic electroluminescent device. The use of this material combination to produce the light-emitting layer in an organic electroluminescent device results in very good performance of these devices, especially in terms of lifetime, especially with equal or improved efficiency and / or operating voltage. The advantages are also particularly evident in the presence of a luminescent component in the light-emitting layer, especially in a concentration between 2% by weight and 15% by weight, especially in combination with a luminophore of formula (5).

[0019] Therefore, the present invention first provides an organic electroluminescent device, which comprises an anode, a cathode and at least one organic layer, wherein the at least one organic layer contains at least one light-emitting layer, wherein the at least one light-emitting layer contains at least one compound of formula (1) as a host material 1 and at least one compound of formula (2) as a host material 2,

[0020]

[0021] The symbols and notations used are as follows:

[0022] X is the same or different in each case and is CR 0 or N, provided that at least two X groups are N;

[0023] Y is selected from O and S;

[0024] L is in each case identical or different and is a single bond or a linker L-1 to L-13,

[0025]

[0026] wherein the linking groups L-1 to L-13 may also be substituted by one or more substituents R, and the dotted lines represent the corresponding bonds to the groups of formula (1);

[0027] R is identical or different in each case and is selected from: CN, a straight-chain alkyl, alkoxy or thioalkyl radical having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl radical having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy radical having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl radical having 5 to 40 aromatic ring atoms;

[0028] Ar1, Ar2 are in each case independently of one another an aryl or heteroaryl group having 5 to 40 aromatic ring atoms and which may be substituted by one or more radicals R;

[0029] A is independently in each case a group of formula (3) or (4),

[0030]

[0031] Ar is independently at each occurrence an aryl group having 6 to 40 aromatic ring atoms which may be substituted by one or more radicals R, or a heteroaryl group having 5 to 40 aromatic ring atoms and containing O as a heteroatom, which may be substituted by one or more radicals R;

[0032] * indicates the bonding site with formula (2);

[0033] a, b, c are in each case independently of one another 0 or 1, wherein the sum of the indices a+b+c is 1 in each case;

[0034] n and m are each independently 0, 1, 2 or 3;

[0035] o is independently at each occurrence 0, 1, 2, 3, 4, 5, 6 or 7;

[0036] p is independently at each occurrence 0, 1, 2, 3, 4, 5, 6, 7 or 8;

[0037] q, r, s, t are in each case independently of one another 0 or 1;

[0038] R 0 R is independently in each case H or an unsubstituted or partially deuterated or fully deuterated aromatic ring system having 6 to 18 carbon atoms.

[0039] The present invention also provides a method for producing an organic electroluminescent device and provides a mixture comprising at least one compound of formula (1) and at least one compound of formula (2), a specific material combination, and a preparation containing such a mixture or material combination. Part of the subject matter of the present invention also relates to the corresponding preferred embodiments described below. Surprising and advantageous effects are achieved by specifically selecting the compound of formula (1) and the compound of formula (2).

[0040] The organic electroluminescent device of the present invention is, for example, an organic light-emitting transistor (OLET), an organic field quenching device (OFQD), an organic light-emitting electrochemical cell (OLEC, LEC, LEEC), an organic laser diode (O-laser), or an organic light-emitting diode (OLED). The organic electroluminescent device of the present invention is especially an organic light-emitting diode or an organic light-emitting electrochemical cell. The device of the present invention is more preferably an OLED.

[0041] The organic layer of the device of the present invention comprising an emissive layer comprising a material combination of at least one compound of formula (1) and at least one compound of formula (2) as described above or below preferably comprises, in addition to such an emissive layer (EML), a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), an electron injection layer (EIL), and / or a hole blocking layer (HBL). The device of the present invention may further comprise a plurality of layers selected from the group consisting of an EML, a HIL, a HTL, an ETL, an EIL, and an HBL.

[0042] However, the device may also comprise further layers which are formed entirely from inorganic materials or are formed entirely from inorganic materials.

[0043] Preferably, the light-emitting layer containing at least one compound of formula (1) and at least one compound of formula (2) is a phosphorescent layer, characterized in that, in addition to the host material combination of compounds of formula (1) and formula (2) as described above, it also contains at least one phosphorescent emitter. Suitable choices of emitters and preferred emitters are described below.

[0044] In the context of the present invention, the aryl group contains 6 to 40 aromatic ring atoms, preferably carbon atoms. In the context of the present invention, the heteroaryl group contains 5 to 40 aromatic ring atoms, wherein the ring atoms contain carbon atoms and at least one heteroatom, provided that the sum of carbon atoms and heteroatoms is at least 5. The heteroatoms are preferably selected from N, O and / or S. The aryl group or heteroaryl group is considered to refer to a simple aromatic ring derived from benzene, i.e., phenyl, or a simple heteroaromatic ring such as pyridine, pyrimidine or thiophene, or a fused aryl or heteroaryl group such as naphthalene, anthracene, phenanthrene, quinoline or isoquinoline. Therefore, the aryl group with 6 to 18 carbon atoms is preferably phenyl, naphthyl, phenanthryl or terphenylidene, wherein the bonding of the aryl group as a substituent is not limited. The aryl or heteroaryl group in the context of the present invention may carry one or more radicals R, wherein the substituent R is as described below.

[0045] Aromatic ring systems in the context of the present invention contain 6 to 40 carbon atoms in the ring system.Aromatic ring systems also contain aryl groups as described above.

[0046] The aromatic ring system having 6 to 18 carbon atoms is preferably selected from phenyl, biphenyl, naphthyl, phenanthrenyl and terphenylidene.

[0047] The heteroaromatic ring system in the context of the present invention contains 5 to 40 ring atoms and at least one heteroatom. Preferred heteroaromatic ring systems have 10 to 40 ring atoms and at least one heteroatom. The heteroaromatic ring system also comprises a heteroaryl group as described above. The heteroatom in the heteroaromatic ring system is preferably selected from N, O and / or S.

[0048] In the context of this invention, an aromatic or heteroaromatic ring system is understood to mean a system that does not necessarily consist exclusively of aryl or heteroaryl groups, but rather in which a plurality of aryl or heteroaryl groups may also be interrupted by non-aromatic units (preferably less than 10% of which are non-H atoms), such as carbon atoms, nitrogen atoms, oxygen atoms, or carbonyl groups. For example, systems such as 9,9'-spirobifluorene, 9,9-diarylfluorene, triarylamines, diaryl ethers, stilbenes, etc. are also considered to be aromatic or heteroaromatic ring systems in the context of this invention, as are systems in which two or more aryl groups are interrupted, for example, by linear or cyclic alkyl groups or by silyl groups. Furthermore, the definition of an aromatic or heteroaromatic ring system also encompasses systems in which two or more aryl or heteroaryl groups are directly bonded to one another, such as biphenyl, terphenyl, quaterphenyl, or bipyridine.

[0049] An aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms and which can be linked to the aromatic or heteroaromatic system via any desired position is taken to mean, for example, a radical derived from benzene, naphthalene, anthracene, benzanthracene, phenanthrene, triphenylene, pyrene, lettuce, perylene, fluoranthene, benzofluoranthene, tetracene, pentacene, benzopyrene, biphenyl, biphenylylidene, terphenyl, biphenylylidene, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene ... Monobenzoindenofluorene, cis- or trans-dibenzoindenofluorene, trimer indene, isotrimer indene, spirotrimer indene, spiroistrimer indene, 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, phenanthroline, Oxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, Azoles, benzophenones Azoles, naphtho Azoles, anthracenes azole, phenanthroline Azoles, isocyanates azole, 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, phen Oxazine, phenothiazine, fluorescent red ring, 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.

[0050] The abbreviations Ar1 and Ar2 are each independently an aryl or heteroaryl radical having 5 to 40 aromatic ring atoms, which may be substituted by one or more radicals R, where the radical R is as defined above or below. The details given for the aryl and heteroaryl radicals having 5 to 40 aromatic ring atoms apply accordingly.

[0051] The abbreviation Ar is, independently at each occurrence, an aryl radical having 6 to 40 aromatic ring atoms and which may be substituted by one or more radicals R, or a heteroaryl radical having 5 to 40 aromatic ring atoms and containing O as a heteroatom, which may be substituted by one or more radicals R, wherein the details of the aryl radical or heteroaryl radical apply correspondingly, as described above. The radical R or radicals R are defined as described above or below.

[0052] A cyclic alkyl, alkoxy or thioalkyl group in the context of the present invention is understood to mean a monocyclic, bicyclic or polycyclic group.

[0053] In the context of the present invention, a linear, branched or cyclic C1- to C 20Alkyl groups are understood as meaning, for example, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, 2-methylbutyl, n-pentyl, sec-pentyl, tert-pentyl, 2-pentyl, neopentyl, cyclopentyl, n-hexyl, sec-hexyl, tert-hexyl, 2-hexyl, 3-hexyl, neohexyl, cyclohexyl, 1-methylcyclopentyl, 2-methylpentyl, n-heptyl, 2-heptyl, 3-heptyl, 4-heptyl, cycloheptyl, 1-methylcyclohexyl, n-octyl, 2-ethylhexyl, cyclooctyl, 1-bicyclo[2.2.2]octyl, 2-bicyclo[2.2.2]octyl, 2-(2,6-dimethyl)octyl, 3-(3,7-dimethyl)octyl, adamantyl, trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, 1,1-dimethyl-n-hexan-1-yl, 1,1-dimethyl-n-heptan-1-yl, 1,1 -dimethyl-n-oct-1-yl, 1,1-dimethyl-n-dec-1-yl, 1,1-dimethyl-n-dodec-1-yl, 1,1-dimethyl-n-tetradec-1-yl, 1,1-dimethyl-n-hexadec-1-yl, 1,1-dimethyl-n-octadec-1-yl, 1,1-diethyl-n-hex-1-yl, 1,1-diethyl-n-hept-1-yl, 1,1-diethyl-n-oct-1-yl, 1,1-diethyl 1-(n-propyl)cyclohexan-1-yl, 1-(n-butyl)cyclohexan-1-yl, 1-(n-hexyl)cyclohexan-1-yl, 1-(n-octyl)cyclohexan-1-yl and 1-(n-decyl)cyclohexan-1-yl.

[0054] Straight or branched C1- to C 20 An alkoxy group is understood as meaning, for example, methoxy, trifluoromethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy or 2-methylbutoxy.

[0055] Straight chain C1- to C 20 A thioalkyl group is understood to mean, for example, an S-alkyl group, such as thiomethyl, 1-thioethyl, 1-thio-isopropyl, 1-thio-n-propyl, 1-thio-isobutyl, 1-thio-n-butyl or 1-thio-tert-butyl.

[0056] An aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms is an O-aryl or O-heteroaryl group and means that the aryl or heteroaryl group is bonded via an oxygen atom, wherein the aryl or heteroaryl group has the meaning given above.

[0057] An aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms means that an alkyl group as defined above is substituted by an aryl or heteroaryl group, wherein the aryl or heteroaryl group has the meaning defined above.

[0058] In the context of the present invention, phosphorescent emitters are understood to be compounds which emit light from an excited state with a high spin multiplicity, i.e. an excited state with a spin state >1, in particular from an excited triplet state. In the context of this application, all luminescent complexes with transition metals or lanthanides are intended to be considered as phosphorescent emitters. A more precise definition is given below.

[0059] When the host material of the emitting layer, which comprises at least one compound of the formula (1) as described above or preferably below and at least one compound of the formula (2) as described above or below, is used for a phosphorescent emitter, it is preferred that its triplet energy is not significantly less than the triplet energy of the phosphorescent emitter. With respect to the triplet energy level, it is preferred that T1(emitter)-T1(matrix)≤0.2 eV, more preferably ≤0.15 eV, most preferably ≤0.1 eV. T1(matrix) is the triplet energy level of the matrix material in the emitting layer, this condition applying to each of the two matrix materials, and T1(emitter) is the triplet energy level of the phosphorescent emitter. If the emitting layer contains more than two matrix materials, the above relationship preferably also applies to each of the other matrix materials.

[0060] The host material 1 present in the device according to the invention and its preferred embodiments are described below. The preferred embodiments of the host material 1 of formula (1) also apply to the mixtures and / or preparations according to the invention.

[0061] In the compound of formula (1), Y is selected from O and S.

[0062] In a preferred embodiment of the host material of formula (1), Y is O.

[0063] Correspondingly, the present invention further provides the organic electroluminescent device as described above, wherein Y in the host material 1 is O.

[0064] In the compounds of formula (1) or compounds of preferred embodiments of the host material of formula (1), the symbol X is N in two cases and CR in one case 0 , or N in three cases.

[0065] Therefore, the substituent

[0066]

[0067] has the following definition, wherein * represents the bonding site to dibenzofuran or dibenzothiophene, and R 0 、Ar 1 and Ar2 Having the definitions or preferably the definitions given above:

[0068]

[0069] R 0 are identical or different in each case and are preferably selected from H or an unsubstituted or partially deuterated or fully deuterated aromatic ring system having 6 to 18 carbon atoms. 0 In each case, R is preferably H or an unsubstituted aromatic ring system having 6 to 18 carbon atoms. 0 More preferred is H in each case.

[0070] Compounds of formula (1) wherein X is N in each case are represented by formula (1a),

[0071]

[0072] wherein Y, L, Ar1, Ar2, R, n, m, o and p have the meanings given above or the meanings given below.

[0073] The compound of formula (1a) is a preferred embodiment of the compound of formula (1). In the compound of formula (1a), Y is preferably O.

[0074] In the compounds of formula (1) or (1a) or the preferably described compounds of formula (1) or (1a), Ar1 and Ar2 are preferably independently of one another an aryl group having 6 to 40 carbon atoms as described above or as preferably described and which may be substituted by one or more groups R, or a dibenzofuranyl or dibenzothiophenyl group which may be substituted by one or more groups R.

[0075] The bonding of aryl groups or dibenzofuranyl groups or dibenzothienyl groups is not restricted here.

[0076] Thus, Ar1 and Ar2 may preferably be selected from the following Ar-1 to Ar-12 groups, in which R has the definition specified or preferably specified above:

[0077]

[0078]

[0079] More preferably, at least one Ar1 or Ar2 is phenyl and the other aromatic substituent is an aryl group having 6 to 40 carbon atoms and which may be substituted by one or more groups R, or is a dibenzofuranyl or dibenzothienyl group; the other aromatic substituent is preferably a group selected from Ar-1 to Ar-12. More preferably, at least one substituent Ar1 or Ar2 is phenyl and the other aromatic substituent is a phenyl group which may be substituted by one or more groups R or is a dibenzofuranyl group. Most preferably, the Ar1 and Ar2 groups are the same. Most preferably, both Ar1 and Ar2 groups are phenyl or both Ar1 and Ar2 groups are dibenzofuranyl, preferably selected from Ar-5, Ar-6, Ar-7 or Ar-11. Most preferably, the aryl or heteroaryl groups in Ar1 and Ar2 are unsubstituted.

[0080] In the compounds of formula (1) and formula (1a) or preferred compounds of formula (1) and (1a), R is in each case identical or different and is selected from: CN, a linear alkyl, alkoxy or thioalkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms. As described above, the substituent R is preferably independently in each case CN or an aryl group having 6 to 40 carbon atoms. R is more preferably independently in each case phenyl.

[0081] In the compounds of formula (1) or (1a) or the preferably described compounds of formula (1) or (1a), n is preferably 0 or 1, wherein R has the meaning given above. More preferably, n is 0.

[0082] In the compounds of formula (1) or (1a) or the preferably described compounds of formula (1) or (1a), m is preferably 0 or 1, wherein R has the meaning given above. More preferably, m is 0.

[0083] In the compounds of formula (1) or (1a) or the preferably described compounds of formula (1) or (1a), o is preferably 0, 1 or 2, wherein R has the meaning given above. More preferably, o is 0.

[0084] In the compounds of formula (1) or (1a) or the preferably described compounds of formula (1) or (1a), p is preferably 0, 1 or 2, wherein R has the meaning given above. More preferably, p is 0.

[0085] In the compounds of formula (1) or (1a) or the preferred descriptions of the compounds of formula (1) or (1a), L is a single bond or L is selected from linkers L-1 to L-13, wherein linkers L-1 to L-13 may also be substituted by one or more substituents R. Preferably, linkers L-1 to L-13 are unsubstituted or have substituents R as described above or as preferably described. More preferably, linkers L-1 to L-13 are unsubstituted.

[0086] In the compounds of formula (1) or (1a) as described above or as preferably described, L is preferably selected from a single bond or linking groups L-1, L-2 and L-3,

[0087]

[0088] Therefore, the present invention also provides an organic electroluminescent device as described above or preferably described, wherein the linker L in the host material 1 is a single bond or is selected from linkers L-1, L-2 and L-3.

[0089] A preferred embodiment of the compounds of formula (1) or (1a) are compounds of formula (1b) in which L is a single bond, n and m are 0 and Y, Ar1, Ar2, R, o and p have the definitions given or preferably given above,

[0090]

[0091] A preferred embodiment of the compounds of formula (1) or (1a) are compounds of formula (1c) in which n and m are 0 and Y, L, Ar1, Ar2, R, o and p have the definitions given above or as preferably given,

[0092]

[0093] In the compounds of the formulae (1), (1a), (1b) and (1c) or the preferably described compounds of the formulae (1), (1a), (1b) and (1c), L can be bonded to the bisspirofluorenyl group at any position.

[0094] L as described above or as preferably described is preferably attached at the 2-, 3- or 4-position of the bisspirofluorenyl group, or most preferably at the 2-position of the bisspirofluorenyl group.

[0095] Examples of suitable host materials of the formula (1) which are selected according to the invention and are preferably used in combination with at least one compound of the formula (2) in the electroluminescent device according to the invention are the structures given in Table 1 below.

[0096] Table 1:

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163] Particularly suitable compounds of the formula (1), (1a), (1b) and / or (1c) for use in the electroluminescent device according to the invention, preferably in combination with at least one compound of the formula (2), are compounds 1 to 10.

[0164] The preparation of compounds of formula (1) or preferred compounds from Table 1 and compounds 1 to 10 is known to those skilled in the art. The compounds can be prepared by synthetic steps known to those skilled in the art, such as halogenation, preferably bromination and subsequent organometallic coupling reactions, such as Suzuki coupling, Heck coupling or Hartwig-Buchwald coupling. The preparation of compounds of formula (1) or preferred compounds of formula (1a) to (1c) and compounds 1 to 10 can be obtained in particular from WO2015169412, in particular the synthesis examples on pages 63 and 77 to 114.

[0165] Compounds of formula (1) to (1c) wherein L is a single bond can be prepared according to Scheme 1 below, wherein X, Y, Ar1, Ar2 have one of the definitions given above and R in Scheme 1 is an alkyl group having 1 to 4 carbon atoms.

[0166] Option 1:

[0167]

[0168] Compounds of formulae (1) to (1c) wherein L is a linker can be prepared according to Scheme 2 below, wherein X, Y, Ar1, Ar2 have one of the definitions given above.

[0169] Option 2:

[0170]

[0171] The host material 2 present in the device according to the invention and its preferred embodiments are described below. The preferred embodiments of the host material 2 of formula (2) also apply to the mixtures and / or preparations according to the invention.

[0172] The host material 2 is at least one compound of formula (2),

[0173]

[0174] The symbols and notations used are as follows:

[0175] R is identical or different in each case and is selected from: CN, a straight-chain alkyl, alkoxy or thioalkyl radical having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl radical having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy radical having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl radical having 5 to 40 aromatic ring atoms;

[0176] A is independently in each case a group of formula (3) or (4),

[0177]

[0178] Ar is independently at each occurrence an aryl group having 6 to 40 aromatic ring atoms, which may be substituted by one or more groups R;

[0179] * indicates the bonding site with formula (2);

[0180] a, b, c are in each case independently of one another 0 or 1, wherein the sum of the indices a+b+c is in each case 1;

[0181] q, r, s, t are in each case independently of one another 0 or 1.

[0182] In one embodiment of the present invention, for the device according to the invention, a compound of formula (2) as described above is selected for use in the light-emitting layer together with a compound of formula (1) as described above or preferably described or with a compound or compounds 1 to 10 from Table 1.

[0183] The compound of formula (2) can be represented by the following formulae (2a), (2b) and (2c):

[0184]

[0185] wherein A, R, q, r, s and t have the definitions given above or below.

[0186] Therefore, the present invention also provides an organic electroluminescent device as described above or preferably described, wherein the host material 2 corresponds to the compound of formula (2a), (2b) or (2c).

[0187] In the compounds of formula (2) and formulae (2a) to (2c) or preferred compounds of formulae (2) and (2a) to (2c) as described above, R in each case is identical or different and is selected from: CN, a linear alkyl, alkoxy or thioalkyl group having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy group having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ring atoms. As described above, the substituent R in each case is preferably independently CN or an aryl group having 6 to 40 carbon atoms. R in each case is more preferably independently phenyl.

[0188] In the compounds of the formula (2) or (2a), (2b) or (2c), the sum of the indices q+r+s is preferably 0 or 1, wherein R has the definition given above.

[0189] In the compounds of formula (2) or (2a), (2b) or (2c), q, r and s are preferably 0 or 1. Preferably, q, r and s are 0.

[0190] In formula (4), the sum of the indices q+r+s is preferably 0 or 1, where R has the definition given above.

[0191] In formula (4), q, r, and s are preferably 0 or 1. Preferably, q, r, and s in formula (4) are preferably 0.

[0192] In formula (3), t is preferably independently in each case 0 or 1. In formula (3), t is preferably identical and 0.

[0193] Ar is, independently at each occurrence, an aryl radical having 6 to 40 aromatic ring atoms which may be substituted by one or more radicals R, or a heteroaryl radical having 5 to 40 aromatic ring atoms and containing O as a heteroatom which may be substituted by one or more radicals R, where the radical R has the meaning given or preferably given above for formula (2).

[0194] Ar is preferably an aryl group having 6 to 18 carbon atoms and substituted by one or more radicals R, wherein the radical has the definitions given or preferably given above for formula (2) or is dibenzofuranyl. Ar is more preferably phenyl, dibenzofuran-substituted phenyl, dibenzothiophene-substituted phenyl, 1,3-biphenyl, 1,4-biphenyl, terphenyl, quaterphenyl, naphthyl, fluorenyl, 9,9-diphenylfluorenyl, bisspirofluorenyl, terphenylidene or dibenzofuranyl.

[0195] In a preferred embodiment of the present invention, A conforms to formula (3) as described above or preferably described.

[0196] Compounds of formula (2) or (2a), (2b) or (2c) wherein A conforms to formula (3) and q, r, s and t are 0 can be represented by formula (2d) and (2e),

[0197]

[0198] in which Ar has the definition given above or preferably given above.

[0199] In a preferred embodiment of the present invention, A conforms to formula (4) as described above or preferably described.

[0200] The present invention therefore also provides an organic electroluminescent device as described above or preferably described, wherein the at least one compound of the formula (2) corresponds to a compound of the formula (2d) or (2e).

[0201] In a preferred embodiment of the compound of formula (2), (2a), (2b), (2c), (2d) or (2e), the substituents of formula (3) and (4) are each bonded to each other at the 2-position or the 5-position of indolo[3,2,1-jk]carbazole as shown below, where the dotted lines represent the bonds to the substituents of formula (3) and (4):

[0202]

[0203] Examples of suitable host materials of the formulae (2), (2a), (2b), (2c), (2d) and (2e) selected according to the invention and preferably used in combination with at least one compound of the formula (1) in the electroluminescent device according to the invention are the structures given in Table 2 below.

[0204] Table 2:

[0205]

[0206]

[0207]

[0208]

[0209]

[0210] Particularly suitable compounds of the formula (2) for use in the electroluminescent device according to the invention, preferably in combination with at least one compound of the formula (1), are compounds 11 to 22:

[0211]

[0212]

[0213] The preparation of compounds of formula (2) or preferred compounds of formula (2), (2a), (2b), (2c), (2d) and (2e) and compounds from Table 2 and compounds 11 to 22 is known to those skilled in the art. The compounds can be prepared by synthetic steps known to those skilled in the art, such as halogenation, preferably bromination and subsequent organometallic coupling reactions such as Suzuki coupling, Heck coupling or Hartwig-Buchwald coupling. The synthesis can be obtained, in particular, from the invention summary of WO2011088877 and KR 20170113318. A portion of the compounds of formula (2) is commercially available.

[0214] Scheme 3 describes the Suzuki reaction in detail:

[0215]

[0216] The host material of the aforementioned formula (1) and its preferred embodiments or compounds from Table 1 and compounds 1 to 10 can be combined in the device of the present invention as needed with the host materials of the aforementioned formulas (2), (2a), (2b), (2c), (2d) and (2e) and their preferred embodiments or compounds from Table 2 or compounds 11 to 22.

[0217] The present invention further provides mixtures comprising at least one compound of the formula (1) and at least one compound of the formula (2),

[0218]

[0219] The symbols and notations used are as follows:

[0220] X is the same or different in each case and is CR 0 or N, provided that at least two X groups are N;

[0221] Y is selected from O and S;

[0222] L is in each case identical or different and is a single bond or a linker L-1 to L-13,

[0223]

[0224]

[0225] wherein the linking groups L-1 to L-13 may also be substituted by one or more substituents R, and the dotted lines represent the corresponding bonds to the groups of formula (1);

[0226] R is identical or different in each case and is selected from: CN, a straight-chain alkyl, alkoxy or thioalkyl radical having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl radical having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy radical having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl radical having 5 to 40 aromatic ring atoms;

[0227] Ar1, Ar2 are in each case independently of one another an aryl or heteroaryl group having 5 to 40 aromatic ring atoms and which may be substituted by one or more radicals R;

[0228] A is independently in each case a group of formula (3) or (4),

[0229]

[0230] Ar is independently at each occurrence an aryl group having 6 to 40 aromatic ring atoms and which may be substituted by one or more groups R;

[0231] * indicates the bonding site with formula (2);

[0232] a, b, c are in each case independently of one another 0 or 1, wherein the sum of the indices a+b+c is 1 in each case;

[0233] n and m are each independently 0, 1, 2 or 3;

[0234] o is independently at each occurrence 0, 1, 2, 3, 4, 5, 6 or 7;

[0235] p is independently at each occurrence 0, 1, 2, 3, 4, 5, 6, 7 or 8;

[0236] q, r, s, t are in each case independently of one another 0 or 1;

[0237] R 0 R is independently in each case H or an unsubstituted or partially deuterated or fully deuterated aromatic ring system having 6 to 18 carbon atoms.

[0238] The details concerning the host materials of the formulae (1) and (2) and their preferred embodiments also apply correspondingly to the mixtures according to the invention.

[0239] Particularly preferred mixtures of host materials of the formula (1) and host materials of the formula (2) for use in the devices of the invention are obtained by combining compounds 1 to 10 with compounds from Table 2.

[0240] Very particularly preferred mixtures of host materials of the formula (1) and host materials of the formula (2) for use in the devices according to the invention are obtained by combining compounds 1 to 10 with compounds 11 to 22, as shown in Table 3 below.

[0241] Table 3:

[0242]

[0243]

[0244] The concentration of the electron-transporting host material of the formula (1) as described above or preferably as described above in the mixture according to the invention or in the light-emitting layer of the device according to the invention is in the range of 5% by weight to 90% by weight, preferably in the range of 10% by weight to 85% by weight, more preferably in the range of 20% by weight to 85% by weight, still more preferably in the range of 30% by weight to 80% by weight, very particularly preferably in the range of 20% by weight to 60% by weight and most preferably in the range of 30% by weight to 50% by weight, based on the entire mixture or based on the entire composition of the light-emitting layer.

[0245] The concentration of the hole-transport host material of formula (2) as described above or preferably as described above in the mixture of the present invention or in the light-emitting layer of the device of the present invention is in the range of 10% by weight or more to 95% by weight, preferably in the range of 15% by weight to 90% by weight, more preferably in the range of 15% by weight to 80% by weight, still more preferably in the range of 20% by weight to 70% by weight, very particularly preferably in the range of 40% by weight to 80% by weight and most preferably in the range of 50% by weight to 70% by weight, based on the entire mixture or based on the entire composition of the light-emitting layer.

[0246] The invention furthermore relates to a mixture which, in addition to the host materials 1 and 2 described above or as preferably described above, in particular mixtures M1 to M120, comprises at least one phosphorescent emitter.

[0247] The invention furthermore relates to an organic electroluminescent device as described above or preferably, wherein the emitting layer comprises, in addition to the host materials 1 and 2 as described above or preferably, in particular the material combinations M1 to M120, at least one phosphorescent emitter.

[0248] The term "phosphorescent emitter" generally includes compounds in which the emission occurs via a spin-forbidden transition from an excited state with a higher spin multiplicity (i.e. a spin state > 1), for example via a transition from a triplet state or a state with a higher spin quantum number, such as a quintet state. This is preferably understood to mean a transition from a triplet state.

[0249] Suitable phosphorescent emitters (triplet emitters) are, in particular, compounds which emit light upon appropriate excitation, preferably in the visible region, and which further contain at least one atom having an atomic number greater than 20, preferably greater than 38 and less than 84, more preferably greater than 56 and less than 80, in particular a metal having such an atomic number. Preferred phosphorescent emitters are compounds containing copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, in particular compounds containing iridium or platinum. In the context of the present invention, all emitting compounds containing the aforementioned metals are regarded as phosphorescent emitters.

[0250] In general, all phosphorescent complexes which are used according to the prior art for phosphorescent OLEDs and as are known to the person skilled in the art in the field of organic electroluminescent devices are suitable.

[0251] Examples of the above-mentioned luminophores are provided by applications WO 2016 / 015815, WO 00 / 70655, WO 2001 / 41512, WO2002 / 02714, WO 2002 / 15645, EP 1191613, EP 1191612, EP 1191614, WO 05 / 033244, WO 05 / 019373、US 2005 / 0258742、WO 2009 / 146770、WO 2010 / 015307、WO 2010 / 031485、WO 2010 / 054731、WO 2010 / 054728、WO 2010 / 086089、WO 2010 / 099852、WO 2010 / 102709, WO 2011 / 032626, WO 2011 / 066898, WO 2011 / 157339, WO 2012 / 007086, WO 2014 / 008982, WO 2014 / 023377, WO 2014 / 094961, WO 2014 / 094960、WO 2015 / 036074、WO 2015 / 104045、WO 2015 / 117718、WO 2016 / 015815、WO 2016 / 124304、WO 2017 / 032439、WO 2015 / 036074、WO 2015 / 117718 and WO Visible in 2016 / 015815.

[0252] Preferred phosphorescent emitters according to the invention conform to formula (5),

[0253]

[0254] The symbols and notations in formula (5) are defined as follows:

[0255] n+m is 3, n is 1 or 2, m is 2 or 1,

[0256] X is N or CR,

[0257] R is H, D, or a branched or straight-chain alkyl group having 1 to 10 carbon atoms, or a partially deuterated or fully deuterated branched or straight-chain alkyl group having 1 to 10 carbon atoms, or a cycloalkyl group having 4 to 7 carbon atoms which may be partially or fully substituted with deuterium.

[0258] Therefore, the present invention also provides an organic electroluminescent device as described above or preferably described, characterized in that the light-emitting layer contains, in addition to the host materials 1 and 2, at least one phosphorescent emitter that meets the above formula (5).

[0259] In the emitter of formula (5), n is preferably 1 and m is preferably 2.

[0260] In the emitter of formula (5), preferably, one X is selected from N and the other X is CR.

[0261] In the emitter of the formula (5), at least one R is preferably different from (not being) H. In the emitter of the formula (5), preferably two R are different from H and have one of the other definitions given above for the emitter of the formula (5).

[0262] Preferred examples of phosphorescent emitters are listed in Table 4 below.

[0263] Table 4:

[0264]

[0265]

[0266]

[0267]

[0268]

[0269]

[0270]

[0271]

[0272]

[0273]

[0274]

[0275]

[0276]

[0277]

[0278]

[0279]

[0280]

[0281] Preferred examples of phosphorescent multipodal emitters are listed in Table 5 below.

[0282] Table 5:

[0283]

[0284]

[0285]

[0286]

[0287]

[0288] In the mixtures according to the invention or in the light-emitting layer of the device according to the invention, it is preferred to combine any of the following mixtures with a compound of formula (5) or a compound from Table 4 or 5: M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15, M16, M17, M18, M19, M20, M21, M22, M23 3. M24, M25, M26, M27, M28, M29, M30, M31, M32, M33, M34, M35, M36, M37, M38, M39, M4 0. M41, M42, M43, M44, M45, M46, M47, M48, M49, M50, M51, M52, M53, M54, M55, M56, M57 , M58, M59, M60, M61, M62, M63, M64, M65, M66, M67, M68, M69, M70, M71, M72, M73, M74 , M75, M76, M77, M78, M79, M80, M81, M82, M83, M84, M85, M86, M87, M88, M89, M90, M91, M92, M93, M94, M95, M96, M97, M98, M99, M100, M101, M102, M103, M104, M105, M106, M 107, M108, M109, M110, M111, M112, M113, M114, M115, M116, M117, M118, M119, M120.

[0289] The light-emitting layer containing at least one phosphorescent light-emitting body in the organic electroluminescent device of the present invention is preferably an infrared light-emitting layer or a yellow, orange, red, green, blue or ultraviolet light-emitting layer, and more preferably a yellow or green light-emitting layer, most preferably a green light-emitting layer.

[0290] A yellow-emitting layer is understood here to mean a layer having a photoluminescence maximum in the range of 540 to 570 nm. An orange-emitting layer is understood to mean a layer having a photoluminescence maximum in the range of 570 to 600 nm. A red-emitting layer is understood to mean a layer having a photoluminescence maximum in the range of 600 to 750 nm. A green-emitting layer is understood to mean a layer having a photoluminescence maximum in the range of 490 to 540 nm. A blue-emitting layer is understood to mean a layer having a photoluminescence maximum in the range of 440 to 490 nm. The photoluminescence maxima of the layers are determined here by measuring the photoluminescence spectrum of a layer having a layer thickness of 50 nm at room temperature, said layer comprising the inventive combination of host materials of the formula (1) and formula (2) with a suitable emitter.

[0291] For example, the photoluminescence spectrum of the layer is recorded using a commercial photoluminescence spectrometer.

[0292] The photoluminescence spectrum of the selected luminophore is usually within 10 -5 The triplet energy T1 (in eV) is determined from the photoluminescence spectrum of the luminophore. First, the peak maximum value Plmax (in nm) of the photoluminescence spectrum is determined. Then, the peak maximum value Plmax (in nm) is converted to eV by the following formula: E(T1, in eV) = 1240 / E(T1, in nm) = 1240 / PLmax (in nm).

[0293] Preferred phosphorescent emitters are therefore infrared emitters, preferably of formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 1.9 eV to about 1.0 eV.

[0294] Preferred phosphorescent emitters are therefore red emitters, preferably of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 2.1 eV to about 1.9 eV.

[0295] Preferred phosphorescent emitters are therefore yellow emitters, preferably of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 2.3 eV to about 2.1 eV.

[0296] Preferred phosphorescent emitters are therefore green emitters, preferably of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 2.5 eV to about 2.3 eV.

[0297] Preferred phosphorescent emitters are therefore blue emitters, preferably of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 3.1 eV to about 2.5 eV.

[0298] Preferred phosphorescent emitters are therefore UV emitters of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably in the range from about 4.0 eV to about 3.1 eV.

[0299] Particularly preferred phosphorescent emitters are therefore green or yellow emitters, preferably having the formula (5) or from Table 4 or 5, as described above.

[0300] Therefore, very particularly preferred phosphorescent emitters are green emitters, preferably of the formula (5) or from Table 4 or 5, whose triplet energy T1 is preferably from about 2.5 eV to about 2.3 eV.

[0301] Most preferably, as mentioned above, a green emitter preferably having formula (5) or from Table 4 or 5 is selected for the composition according to the invention or the light-emitting layer according to the invention.

[0302] Fluorescent emitters may also be present in the light-emitting layer of the device according to the invention.

[0303] Preferred fluorescent emitters are selected from the class of arylamines. In the context of the present invention, arylamines or aromatic amines are understood to mean compounds containing three substituted or unsubstituted aromatic or heteroaromatic ring systems directly bonded to the nitrogen. Preferably, at least one of these aromatic or heteroaromatic ring systems is a fused ring system, more preferably having at least 14 aromatic ring atoms. Preferred examples of these are aromatic anthraceneamines, aromatic anthracenediamines, aromatic pyrenamines, aromatic pyrenediamines, aromatic leucamines, or aromatic leucamines. Aromatic anthraceneamines are understood to mean compounds in which the diarylamino group is directly bonded to the anthracene group, preferably in the 9-position. Aromatic anthracenediamines are understood to mean compounds in which two diarylamino groups are directly bonded to the anthracene group, preferably in the 9- and 10-positions. Aromatic pyrenamines, pyrenediamines, leucamines, and leucamines are defined in a similar manner, with the diarylamino groups preferably bonded to the pyrene group in the 1-position or the 1- and 6-positions. Further preferred fluorescent emitters are: indenofluorenamine or indenofluorenediamine, for example according to WO 2006 / 108497 or WO 2006 / 122630; benzoindenofluorenamine or benzoindenofluorenediamine, for example according to WO 2008 / 006449; and dibenzoindenofluorenamine or dibenzoindenofluorenediamine, for example according to WO 2007 / 140847; and the indenofluorene derivatives with fused aryl groups disclosed in WO 2010 / 012328.

[0304] In another preferred embodiment of the present invention, at least one light-emitting layer of the organic electroluminescent device may further comprise, in addition to the host materials 1 and 2 as described above or preferably described, another host material or matrix material, referred to as a mixed matrix system. The mixed matrix system preferably comprises three or four different matrix materials, more preferably three different matrix materials (in other words, a further matrix component in addition to the host materials 1 and 2 as described above). Particularly suitable matrix materials that can be used in combination as matrix components in a mixed matrix system are selected from wide bandgap materials, bipolar host materials, electron transport materials (ETMs) and hole transport materials (HTMs).

[0305] A wide bandgap material in this context is understood to mean a material within the disclosure of US 7,294,849, characterized by a bandgap of at least 3.5 eV, said bandgap being understood to mean the gap between the HOMO and LUMO energies of a material.

[0306] In one embodiment of the present invention, in addition to the components of the electron transport host material of formula (1) and the hole transport host material of formula (2), the mixture does not contain any other components, i.e., functional materials. These are material mixtures used directly in the manufacture of the light-emitting layer. These mixtures are also referred to as premixed systems, which are used as the only material source in the vapor deposition of the host material of the light-emitting layer and have a constant mixing ratio during vapor deposition. In this way, vapor deposition of a layer with uniformly distributed components can be achieved in a simple and rapid manner without the need for precise control of multiple material sources.

[0307] In an alternative embodiment of the present invention, in addition to the components of the electron transport host material of formula (1) and the hole transport host material of formula (2), the mixture also contains a phosphorescent emitter as described above. As described above, given the appropriate mixing ratio during vapor deposition, this mixture can also be used as the only material source.

[0308] Thus, the components or constituents of the light-emitting layer of the device of the present invention can be vapor deposited or processed from solution. Host materials 1 and 2, as described above or as preferably described, are provided, optionally in combination with materials for the phosphorescent emitter, as described above or as preferably described, in a formulation containing at least one solvent. These formulations can be, for example, solutions, dispersions, or emulsions. For this purpose, mixtures of two or more solvents can preferably be used.

[0309] The present invention therefore also provides a preparation comprising the inventive mixture of host materials 1 and 2 as described above, optionally in combination with a phosphorescent emitter as described above or as preferably described, and at least one solvent.

[0310] Suitable and preferred solvents are, for example, toluene, anisole, o-xylene, m-xylene or p-xylene, methyl benzoate, mesitylene, tetralin, veratrole, THF, methyl-THF, THP, chlorobenzene, dimethylbenzene, alkane, phenoxytoluene, in particular 3-phenoxytoluene, (-)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol, 2-pyrrolidone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, acetophenone, α-terpineol, benzothiazole, butyl benzoate, isopropylbenzene, cyclohexanol, cyclohexanone, cyclohexylbenzene, decalin, dodecahydronaphthalene, Alkylbenzenes, ethyl benzoate, indane, methyl benzoate, NMP, p-isopropyl toluene, 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, hexamethylindane, or mixtures of these solvents.

[0311] The preparations here may also comprise at least one further organic or inorganic compound which is likewise used in the emitting layer of the device according to the invention, in particular further emitting compounds and / or further matrix materials.

[0312] The emitting layer in the device according to the invention preferably contains from 99.9% to 1% by volume, preferably from 99% to 10% by volume, particularly preferably from 98% to 60% by volume, and very particularly preferably from 97% to 80% by volume of a matrix material comprising at least one compound of the formula (1) according to the preferred embodiments and at least one compound of the formula (2), based on the total composition of the emitter and matrix material. Accordingly, the emitting layer in the device according to the invention preferably contains from 0.1% to 99% by volume, preferably from 1% to 90% by volume, more preferably from 2% to 40% by volume, and most preferably from 3% to 20% by volume of emitter, based on the total composition of the emitting layer comprising emitter and matrix material. If the compounds are processed from solution, the corresponding amounts in % by weight are preferably used instead of the amounts stated in % by volume.

[0313] According to preferred embodiments and emitting compounds, the emitting layer in the device of the present invention preferably contains the matrix material of formula (1) and the matrix material of formula (2) in a volume ratio of 3:1 to 1:3, preferably 1:2.5 to 1:1, more preferably 1:2 to 1:1. If the compounds are processed from solution, the corresponding ratios in weight % are preferably used instead of the above ratios in volume %.

[0314] The sequence of layers in the organic electroluminescent device of the invention is preferably as follows:

[0315] Anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode.

[0316] The stated order of layers is a preferred order.

[0317] At the same time, it should be pointed out again that not all of the layers mentioned must be present, and / or other layers may be present in addition.

[0318] The organic electroluminescent device of the present invention may contain two or more light-emitting layers. As described above, at least one of the light-emitting layers is the following light-emitting layer of the present invention, which contains at least one compound of formula (1) as the host material 1 and at least one compound of formula (2) as the host material 2. More preferably, these light-emitting layers have a total of multiple luminescence maxima between 380nm and 750nm in this case, so that the overall result is white light-emitting; in other words, various light-emitting compounds that can emit fluorescence or emit phosphorescence and emit blue or yellow or orange or red light are used in the light-emitting layer. Particularly preferred is a three-layer system, i.e. a system with three light-emitting layers, wherein the three layers show blue, green and orange or red light emission (see, for example, WO 2005 / 011013 for the basic structure). It should be noted that in order to produce white light, it may also be appropriate to use a single light-emitting compound that emits light in a wide wavelength range instead of a plurality of light-emitting compounds that emit light in different colors.

[0319] Suitable charge transport materials that can be used in the hole injection or hole transport layer or electron blocking layer or electron transport layer of the organic electroluminescent device according to the invention are, for example, the compounds disclosed in Y. Shirota et al., Chem. Rev. 2007, 107(4), 953-1010 or other materials employed in these layers according to the prior art.

[0320] The materials that can be used for the electron transport layer are any materials that are used as electron transport materials in the electron transport layer according to the prior art. Particularly suitable are aluminum complexes such as Alq3, zirconium complexes such as Zrq4, benzimidazole derivatives, triazine derivatives, pyrimidine derivatives, pyridine derivatives, pyrazine derivatives, quinoxaline derivatives, quinoline derivatives, Oxadiazole derivatives, aromatic ketones, lactams, boranes, phosphadiazolinyl derivatives and phosphine oxide derivatives. Further suitable materials are derivatives of the above compounds, as disclosed in JP 2000 / 053957, WO 2003 / 060956, WO 2004 / 028217, WO 2004 / 080975 and WO 2010 / 072300.

[0321] Preferred hole-transport materials are, in particular, materials which can be used in hole-transport, hole-injection or electron-blocking layers, such as indenofluorenamine derivatives (for example according to WO 06 / 122630 or WO 06 / 100896), amine derivatives disclosed in EP 1661888, hexaazaterphenylidene derivatives (for example according to WO 01 / 049806), amine derivatives containing fused aromatic rings (for example according to US Pat. No. 5,061,569), amine derivatives disclosed in WO 95 / 09147, monobenzoindenofluorenamine (for example according to WO 08 / 006449), dibenzoindenofluorenamine (for example according to WO 07 / 140847), spirobifluorenamine (for example according to WO 2012 / 034627 or the as yet unpublished EP 12000929.5), fluorenamine (for example according to WO 2014 / 015937, WO 2014 / 015938 and WO 2014 / 015935), spirobibenzopyranamines (for example according to WO 2013 / 083216) and dihydroacridine derivatives (for example according to WO 2012 / 150001).

[0322] The cathode suitable for the device of the present invention is a metal, metal alloy or multilayer structure with low work function, which comprises various metals such as alkaline earth metals, alkali metals, main group metals or lanthanides (such as Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.). In addition, it is suitable to comprise an alloy of alkali metal or alkaline earth metal and silver, such as an alloy comprising magnesium and silver. In the case of a multilayer structure, in addition to the metal, other metals such as Ag or Al with relatively high work function can also be used, in which case a combination of the metals such as Ca / Ag, Mg / Ag or Ba / Ag is generally used. A thin intermediate layer of a material with a high dielectric constant can also be preferably introduced between the metal cathode and the organic semiconductor. Examples that can be used for this purpose are alkali metal fluorides or alkaline earth metal fluorides, as well as corresponding oxides or carbonates (such as LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.). In addition, lithium quinoline (LiQ) can also be used for this purpose. The layer thickness of this layer is preferably between 0.5nm and 5nm.

[0323] Preferred anodes are materials with high work function. Preferably, the anode has a work function greater than 4.5 eV relative to vacuum. Firstly, metals with high redox potentials such as Ag, Pt or Au are suitable for this purpose. Secondly, metal / metal oxide electrodes (e.g. Al / Ni / NiO x 、Al / PtO x) may also be preferred. For some applications, at least one of the electrodes must be transparent or partially transparent to ensure illumination of the organic material (organic solar cells) or luminescence (OLED, O-laser). Preferred anode materials here are conductive mixed metal oxides. Particularly preferred are indium tin oxide (ITO) or indium zinc oxide (IZO). Also preferred are conductive doped organic materials, in particular conductive doped polymers. In addition, the anode can also consist of two or more layers, for example an inner layer of ITO and an outer layer of a metal oxide, the metal oxide being preferably tungsten oxide, molybdenum oxide or vanadium oxide.

[0324] During production, the organic electroluminescent device of the invention is appropriately (depending on the application) structured, provided with contacts and finally sealed, since the lifetime of the device of the invention is shortened in the presence of water and / or air.

[0325] The production of the device according to the invention is not restricted here. The organic layer or layers including the light-emitting layer can be applied by sublimation. In this case, the organic layer or layers can be applied by sublimation. -5 mbar, preferably below 10 -6 The material is applied by vapor deposition in a vacuum sublimation system at an initial pressure of 10 mbar. However, in this case, the initial pressure can also be lower, for example less than 10 -7 millibar.

[0326] The organic electroluminescent device according to the invention is preferably characterized in that one or more layers are applied by the OVPD (Organic Vapor Phase Deposition) method or by means of carrier gas sublimation. -5 The material is applied at a pressure of mbar to 1 bar. A special example of this method is the OVJP (Organic Vapor Jet) method, in which the material is applied directly via a nozzle and thereby structured (eg MS Arnold et al., Appl. Phys. Lett. 2008, 92, 053301).

[0327] Another preferred feature of the organic electroluminescent device of the present invention is that one or more organic layers comprising the composition of the present invention are produced from solution, for example by spin coating, or by any printing method such as screen printing, flexographic printing, nozzle printing or offset printing, but more preferably LITI (light-induced thermal imaging, thermal transfer) or inkjet printing. To this end, soluble host materials 1 and 2 and a phosphorescent emitter are required. The advantage of processing from solution is that, for example, the light-emitting layer can be applied in a very simple and inexpensive manner. This technology is particularly suitable for large-scale production of organic electroluminescent devices.

[0328] Furthermore, hybrid methods are possible in which, for example, one or more layers are applied from solution and one or more further layers are applied by vapor deposition.

[0329] These methods are generally known to those skilled in the art and can be applied to organic electroluminescent devices.

[0330] The present invention therefore also provides a process for producing an organic electroluminescent device according to the invention as described above or preferably, characterized in that the emitting layer is applied by vapor deposition, in particular by sublimation and / or by the OVPD (Organic Vapor Phase Deposition) method and / or by sublimation with the aid of a carrier gas, or from solution, in particular by spin coating or by printing methods.

[0331] In the case of production by vapor deposition, there are, in principle, two ways in which the light-emitting layer according to the invention can be applied or vapor-deposited onto any substrate or previous layer. First, the materials used can each be initially charged into a material source and ultimately evaporated from different material sources ("co-evaporation"). Secondly, the various materials can be premixed (premix system), and the mixture can initially be charged into a single material source, from which it can ultimately be evaporated ("premix evaporation"). In this way, vapor deposition of a light-emitting layer with a uniform distribution of the components can be achieved in a simple and rapid manner, without the need for precise control of multiple material sources.

[0332] The present invention therefore also provides a process for producing a device according to the invention, characterized in that at least one compound of the formula (1) as described above or preferably described and at least one compound of the formula (2) as described above or preferably described are deposited from at least two material sources successively or simultaneously from the gas phase, optionally together with at least one phosphorescent emitter as described above or preferably described, and form the emitting layer.

[0333] In a preferred embodiment of the invention, the light-emitting layer is applied by vapor deposition, wherein the constituent parts of the composition are premixed and evaporated from a single material source.

[0334] The present invention therefore also provides a process for producing a device according to the invention, characterized in that at least one compound of the formula (1) and at least one compound of the formula (2) are deposited as a mixture with at least one phosphorescent emitter continuously or simultaneously from the gas phase and form the emitting layer.

[0335] The present invention also provides a process for producing a device according to the invention as described above or preferably described, characterized in that at least one compound of the formula (1) and at least one compound of the formula (2) as described above or preferably described are applied from solution together with at least one phosphorescent emitter to form the emitting layer.

[0336] The device of the present invention has the following surprising advantages compared with the prior art:

[0337] As mentioned above, the use of the material combination of host materials 1 and 2 leads in particular to an increase in the device lifetime.

[0338] As becomes clear in the examples given below, by comparing the data for OLEDs with combinations from the prior art, it can be determined that the inventive combinations of matrix materials in the EML lead to increases in the lifetime of the devices of about 20% to 240%, regardless of the emitter concentration.

[0339] It should be noted that variations of the embodiments described in this invention are within the scope of this invention. Unless expressly excluded, any feature disclosed in this invention may be replaced by an alternative feature having the same, equivalent, or similar purpose. Therefore, unless otherwise stated, any feature disclosed in this invention should be considered an example of a generic series or an equivalent or similar feature.

[0340] Unless specific features and / or steps are mutually exclusive, all features of the present invention can be combined with each other in any way. This is particularly applicable to the preferred features of the present invention. Similarly, features of non-essential combinations can be used individually (and not in combination).

[0341] The technical teachings disclosed in this invention can be refined and combined with other examples.

[0342] The present invention will be described in more detail below with reference to examples, but it is not intended to limit the invention thereby.

[0343] General approach:

[0344] In all quantum chemical calculations, the Gaussian 16 (Revision B.01) software package was used. The neutral singlet ground state was optimized to the B3LYP / 6-31G(d) level. At the B3LYP / 6-31G(d) level, the HOMO and LUMO values ​​were determined for the B3LYP / 6-31G(d) optimized ground state energy. TD-DFT singlet and triplet excitations (vertical excitations) were then calculated using the same method (B3LYP / 6-31G(d)), utilizing the optimized ground state geometry. Standard settings for SCF and gradient convergence were used.

[0345] The energy calculation gives the HOMO as the last orbital occupied by two electrons (αocc. eigenvalue) and the LUMO as the first unoccupied orbital (αvirt. eigenvalue) in Hartree, where HEh and LEh denote the HOMO energy (in Hartree) and the LUMO energy (in Hartree), respectively. The HOMO and LUMO values ​​(in electron volts) are determined from this, which are calibrated by cyclic voltammetry measurements, as follows:

[0346] HOMOcorr=0.90603*HOMO-0.84836

[0347] LUMOcorr=0.99687*LUMO-0.72445.

[0348] The triplet energy level T1 of a material is defined as the relative excitation energy (in eV) of the triplet state with the lowest energy found by quantum chemical energy calculations.

[0349] The singlet energy level S1 of a material is defined as the relative excitation energy (in eV) of the singlet state with the second lowest energy found by quantum chemical energy calculations.

[0350] The singlet state with the lowest energy is called S0.

[0351] The method described herein is independent of the software package used and always gives the same results. Examples of commonly used programs for this purpose are "Gaussian 09" (Gaussian) and Q-Chem 4.1 (Q Chem). In this case, the software package "Gaussian 16 (Revision B.01)" was used to calculate the energies.

[0352] Example 1: Production of OLED

[0353] The use of the material combinations according to the invention in OLEDs in comparison with material combinations from the prior art is presented in the following Examples V1 to Ex24 (see Tables 6 and 7).

[0354] Pretreatment of Examples V1 to Ex24: Glass panes coated with structured ITO (indium tin oxide) with a thickness of 50 nm were treated first with oxygen plasma and then with argon plasma before coating. These plasma-treated glass panes formed the substrates to which the OLEDs were applied.

[0355] OLEDs essentially have the following layer structure: substrate / hole injection layer (HIL) / hole transport layer (HTL) / electron blocking layer (EBL) / emitting 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 aluminum layer. The precise structure of the OLED is shown in Table 6. The materials required for OLED production are shown in Table 8. The device data for the OLEDs are listed in Table 7. Examples V1 and V4 are comparative examples with electron-transporting hosts according to the prior art WO2011088877.

[0356] Examples V2, V3 and V5, V6 are comparative examples with electron transport hosts according to the prior art (eg known from US 20180337348).

[0357] Examples Ex1 to Ex24 show data for OLEDs according to the invention.

[0358] All materials are applied by thermal vapor deposition in a vacuum chamber. In this case, the light-emitting layer always consists of at least two matrix materials and a luminescent dopant (emitter), which is added to the matrix materials in specific volume ratios by co-evaporation. A detailed description such as SoA1:CoH1:TEG1 (45%:45%:10%) means that the SoA1 material is present in the layer in a volume ratio of 45%, CoH1 in a volume ratio of 45%, and TEG1 in a volume ratio of 10%. Similarly, the electron-transport layer can also consist of a mixture of two materials.

[0359] The OLEDs were characterized in a standard manner. For this purpose, the electroluminescence spectrum and the current-voltage-luminous density characteristic (IUL characteristic) were measured. From this, the EQE and the current efficiency SE (in cd / A) were calculated. The SE calculation was performed based on the presence of Lambertian luminescence characteristics.

[0360] The lifetime LD is defined as the time it takes for a current to flow in a constant current density j0 at a constant current density of cd / m 2 The time it takes for the luminous density measured in the forward direction to drop from the initial luminous density to a specific proportion L1. The number L1=80% in Table 7 means that the lifetime reported in the LD column corresponds to the lifetime in cd / m 2 The time it takes for the luminous density of a unit to drop to 80% of its initial value.

[0361] Use of the mixtures according to the invention in OLEDs

[0362] The material combination of the present invention can be used in the emission layer of a phosphorescent green OLED. The combination of the compounds CoH1 and CoH3 of the present invention with compounds Eg1 to Eg6 is used as a matrix material in the emission layer in Examples Ex1 to Ex12.

[0363] The corresponding comparative examples V1 to V6 relate to the combination of the compounds CoH1 and CoH3 with the compounds SoA1 to SoA3 used as matrix material in the light-emitting layer in examples V1 to V6.

[0364] When comparing the inventive examples with the corresponding comparative examples (see above), it is clear that the inventive examples each show a clear advantage in terms of device lifetime.

[0365] Table 6: Structure of OLED

[0366]

[0367]

[0368] Table 7: OLED data

[0369] example <![CDATA[j0(mA / cm 2 )]]> L1(％) LD(h) V1 40 80 210 V2 40 80 590 V3 40 80 320 Ex1 40 80 705 Ex2 40 80 660 Ex3 40 80 715 Ex4 40 80 670 Ex5 40 80 650 Ex6 40 80 690 V4 40 80 220 V5 40 80 605 V6 40 80 325 Ex7 40 80 720 Ex8 40 80 675 Ex9 40 80 725 Ex10 40 80 680 Ex11 40 80 670 Ex12 40 80 705 Ex13 40 80 1410 Ex14 40 80 1330 Ex15 40 80 1450 Ex16 40 80 1390 Ex17 40 80 1430 Ex18 40 80 1420 Ex19 40 80 1050 Ex20 40 80 920 Ex21 40 80 1090 Ex22 40 80 940 Ex23 40 80 960 Ex24 40 80 1030

[0370] Table 8: Structural formulas of materials used in OLEDs

[0371]

[0372]

[0373]

Claims

1. An organic electroluminescent device comprising an anode, a cathode, and at least one organic layer, wherein the at least one organic layer comprises at least one light-emitting layer, wherein the at least one light-emitting layer comprises at least one compound of formula (1) as a host material 1 and at least one compound of formula (2) as a host material 2, The symbols and notations used are as follows: X is the same or different in each case and is CR 0 or N, provided that at least two X groups are N; Y is selected from O and S; L is in each case identical or different and is a single bond or a linker L-1 to L-13, wherein the linking groups L-1 to L-13 may also be substituted by one or more substituents R, and the dotted lines represent the corresponding bonds to the groups of formula (1); R is identical or different in each case and is selected from: CN, a straight-chain alkyl, alkoxy or thioalkyl radical having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl radical having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy radical having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl radical having 5 to 40 aromatic ring atoms; Ar1, Ar2 are in each case independently of one another an aryl or heteroaryl group having 5 to 40 aromatic ring atoms and which may be substituted by one or more radicals R; A is independently in each case a group of formula (3) or (4), Ar is, independently at each occurrence, an aryl group having 6 to 40 aromatic ring atoms which may be substituted by one or more radicals R, or a heteroaryl group having 5 to 40 aromatic ring atoms and containing O as a heteroatom, which may be substituted by one or more radicals R; * represents the bonding site with the formula (2); a, b, c are in each case independently of one another 0 or 1, wherein the sum of the indices a+b+c is 1 in each case; n and m are each independently 0, 1, 2 or 3; o is independently at each occurrence 0, 1, 2, 3, 4, 5, 6 or 7; p is independently at each occurrence 0, 1, 2, 3, 4, 5, 6, 7 or 8; q, r, s, t are in each case independently of one another 0 or 1; R 0 R is independently in each case H or an unsubstituted or partially deuterated or fully deuterated aromatic ring system having 6 to 18 carbon atoms.

2. The organic electroluminescent device according to claim 1, wherein Y in the host material 1 is O.

3. The organic electroluminescent device according to claim 1, wherein The compound of formula (1) corresponds to the compound of formula (1a), wherein Y, L, Ar1, Ar2, R, n, m, o and p have the meanings as defined in claim 1.

4. The organic electroluminescent device according to claim 1, wherein Ar1 and Ar2 in the host material 1 are each independently an aryl group having 6 to 40 carbon atoms which may be substituted by one or more R groups, or a dibenzofuranyl or dibenzothiophenyl group which may be substituted by one or more R groups.

5. The organic electroluminescent device according to claim 1, wherein R in Host Material 1 or Host Material 2 is CN or an aryl group having 6 to 40 carbon atoms.

6. The organic electroluminescent device according to claim 1, characterized in that The main material 2 conforms to one of the formulas (2a), (2b) or (2c), The symbols and signs A, R, q, r and s used herein are as defined in claim 1.

7. The organic electroluminescent device according to claim 1, wherein L in the host material 1 is a single bond or a linking group L-1, L-2 or L-3.

8. The organic electroluminescent device according to claim 1, wherein Ar in the host material 2 is an aryl group having 6 to 18 carbon atoms and which may be substituted with one or more groups R, or a dibenzofuranyl group.

9. The organic electroluminescent device according to claim 8, characterized in that: Ar in the host material 2 is phenyl, dibenzofuran-substituted phenyl, dibenzothiophene-substituted phenyl, 1,3-biphenyl, 1,4-biphenyl, terphenyl, quaterphenyl, naphthyl, fluorenyl, 9,9-diphenylfluorenyl, bisspirofluorenyl, terphenylidene or dibenzofuranyl.

10. The organic electroluminescent device according to claim 1, wherein the compound of formula (1) is selected from the following compounds 11. The organic electroluminescent device according to claim 1, wherein the compound of formula (2) is selected from the following compounds 12. The organic electroluminescent device according to claim 1, wherein The organic electroluminescent device is an electroluminescent device selected from the following: organic light emitting transistor (OLET), organic field quenching device (OFQD), organic light emitting electrochemical cell (OLEC, LEC, LEEC), organic laser diode (O-laser) and organic light emitting diode (OLED).

13. The organic electroluminescent device according to claim 1, wherein In addition to the emission layer (EML), the organic electroluminescent device further includes a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), an electron injection layer (EIL) and / or a hole blocking layer (HBL).

14. The organic electroluminescent device according to claim 1, characterized in that: In addition to the at least one host material 1 and the at least one host material 2, the light-emitting layer also contains at least one phosphorescent emitter.

15. The organic electroluminescent device according to claim 14, characterized in that: The phosphorescent light-emitting body conforms to formula (5), The symbols and notations in formula (5) are defined as follows: n+m is 3, n is 1 or 2, m is 2 or 1, X is N or CR, R is H, D, or a branched or straight-chain alkyl group having 1 to 10 carbon atoms; or a partially deuterated or fully deuterated branched or straight-chain alkyl group having 1 to 10 carbon atoms; or a cycloalkyl group having 4 to 7 carbon atoms which may be partially or fully substituted with deuterium.

16. A method for producing a device according to any one of claims 1 to 15, characterized in that The emitting layer is applied by vapor deposition or from solution.

17. The method according to claim 16, characterized in that The at least one compound of the formula (1) and the at least one compound of the formula (2) are deposited from at least two material sources successively or simultaneously from the gas phase, optionally together with the at least one phosphorescent emitter, and form the emitting layer.

18. The method according to claim 16, characterized in that The at least one compound of the formula (1) and the at least one compound of the formula (2) are deposited as a mixture with the at least one phosphorescent emitter successively or simultaneously from the gas phase and form the emitting layer.

19. The method according to claim 16, wherein The at least one compound of the formula (1) and the at least one compound of the formula (2) are applied together with the at least one phosphorescent emitter from solution, thereby forming the emitting layer.

20. A mixture comprising at least one compound of formula (1) and at least one compound of formula (2), The symbols and notations used are as follows: X is the same or different in each case and is CR 0 or N, provided that at least two X groups are N; Y is selected from O and S; L is in each case identical or different and is a single bond or a linker L-1 to L-13, wherein the linking groups L-1 to L-13 may also be substituted by one or more substituents R, and the dotted lines represent the corresponding bonds connected to the groups of formula (1); R is identical or different in each case and is selected from: CN, a straight-chain alkyl, alkoxy or thioalkyl radical having 1 to 20 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl radical having 3 to 20 carbon atoms, an aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, an aryloxy or heteroaryloxy radical having 5 to 40 aromatic ring atoms, or an aralkyl or heteroaralkyl radical having 5 to 40 aromatic ring atoms; Ar1, Ar2 are in each case independently of one another an aryl or heteroaryl group having 5 to 40 aromatic ring atoms and which may be substituted by one or more radicals R; A is independently in each case a group of formula (3) or (4), Ar is, independently at each occurrence, an aryl group having 6 to 40 aromatic ring atoms which may be substituted by one or more radicals R, or a heteroaryl group having 5 to 40 aromatic ring atoms and containing O as a heteroatom, which may be substituted by one or more radicals R; * represents the bonding site with the formula (2); a, b, c are in each case independently of one another 0 or 1, wherein the sum of the indices a+b+c is 1 in each case; n and m are each independently 0, 1, 2 or 3; o is independently at each occurrence 0, 1, 2, 3, 4, 5, 6 or 7; p is independently at each occurrence 0, 1, 2, 3, 4, 5, 6, 7 or 8; q, r, s, t are in each case independently of one another 0 or 1; R 0 R is independently in each case H or an unsubstituted or partially deuterated or fully deuterated aromatic ring system having 6 to 18 carbon atoms.

21. The mixture according to claim 20, characterized in that The mixture consists of at least one compound of the formula (1), at least one compound of the formula (2) and a phosphorescent emitter.

22. A formulation comprising the mixture according to claim 20 or 21 and at least one solvent.

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