Compounds for electronic devices

Abstract

The invention relates to compounds of the formula (I), to methods for producing compounds of the formula (I), to the use of compounds of the formula (I) in electronic devices, and to electronic devices containing a compound of the formula (I).

Description

[0001] Compounds for electronic devices This application relates to aromatic amines that have certain aromatic or heteroaromatic ring systems on the amine nitrogen atom. The compounds are suitable for use in electronic devices. Electronic devices within the meaning of this application are understood to mean so-called organic electronic devices (organic electronic devices) that contain organic semiconductor materials as functional materials. In particular, this includes OLEDs (organic electroluminescent devices). The term OLEDs refers to electronic devices that have one or more layers containing organic compounds and emit light when an electrical voltage is applied. The structure and general operating principle of OLEDs are known to those skilled in the art.There is great interest in improving the performance of electronic devices, particularly OLEDs. A completely satisfactory solution has not yet been found in these areas. Emission layers and layers with hole-transporting functions have a significant influence on the performance of electronic devices. New compounds are still being sought for use in these layers, particularly hole-transporting compounds and compounds that can serve as hole-transporting matrix materials, particularly for phosphorescent emitters, in an emitting layer. For this purpose, compounds are particularly sought that exhibit a high glass transition temperature, high stability, and high hole conductivity. High compound stability is a prerequisite for achieving a long service life of the electronic device.Furthermore, a sufficiently low sublimation temperature is of interest and preferred in order to be able to produce electronic devices containing the compound using vapor deposition methods. Furthermore, a sufficiently high HOMO of the compounds is of interest and preferred. Furthermore, compounds are sought whose use in electronic devices leads to improved device performance, in particular high efficiency, long lifetime, and low operating voltage. In the prior art, triarylamine compounds such as spirobifluorenamines and fluorenamines are known in particular as hole-transport materials and hole-transporting matrix materials for electronic devices. However, there is still a need for improvement with regard to the above-mentioned properties.It has now been found that aromatic amines according to the formulas below, which are characterized by having certain aromatic or heteroaromatic ring systems on the amine nitrogen atom, are outstandingly suitable for use in electronic devices. They are particularly suitable for use in OLEDs, particularly therein for use as hole-transport materials and for use as hole-transporting matrix materials, in particular for phosphorescent emitters. The compounds lead to long lifetimes, high efficiency, and low operating voltage of the devices. Furthermore, the compounds found preferably have a high glass transition temperature, high stability, a low sublimation temperature, good solubility, good synthetic accessibility, a sufficiently high HOMO, and high hole conductivity.The present application relates to an electronic device comprising an anode, a cathode, an emitting layer, and a layer comprising a compound of formula (I) arranged between the anode and the emitting layer.

[0002] where the following applies to the variables occurring: G is a group according to formula (G), which is bonded to the rest of formula (I) via one of the free positions on the benzene rings, where the other free positions on the benzene rings are each bonded to a radical R 1 are substituted; X 1 is O or S; X 2 is C(R 2 )2or Si(R 2 )2; X 3 is C(R 2 )2or Si(R 2 )2; Ar L is an aromatic ring system with 6 to 40 aromatic ring atoms, which is linked to residues R 3 substituted, or a heteroaromatic ring system with 5 to 40 aromatic ring atoms, which is substituted with residues R 3is substituted; Ar 1 , Ar 2 is, identically or differently, an aromatic ring system with 6 to 40 aromatic ring atoms, which is substituted with radicals R 4 substituted, or a heteroaromatic ring system with 5 to 25 aromatic ring atoms, which is substituted with radicals R 4 is substituted, where Ar 1 and Ar 2 can optionally be linked to each other via a bond or a group E; E is C(R 4 )2, -C(R 4 )2-C(R 4 )2-, -C(R 4 )=C(R 4 )-, C=O, Si(R 4 )2, NR 4 , O, S, S=O, or SO2; R 1 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5, straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 1 may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 2is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5 , straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 2 may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5-, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 3 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5 , straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 3may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 4 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5, straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each substituted by radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 5 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 6 , CN, Si(R 6 )3, N(R 6)2, P(=O)(R 6 )2, OR 6 , S(=O)R 6 , S(=O)2R 6 , straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each substituted by radicals R 6 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 6 C=CR 6 -, -C≡C-, Si(R 6 )2, C=O, C=NR 6 , -C(=O)O-, -C(=O)NR 6 -, NR 6 , P(=O)(R 6 ), -O-, -S-, SO or SO2; R 6is selected, identically or differently at each occurrence, from H, D, F, Cl, Br, I, CN, alkyl or alkoxy groups having 1 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; and wherein said alkyl, alkoxy, alkenyl and alkynyl groups, aromatic ring systems and heteroaromatic ring systems may be substituted by one or more radicals selected from F and CN; n is 0 or 1, where for n=0 the group G and the nitrogen atom in formula (I) are directly bonded to one another. That in formula (G) the group as nonspecifically bound to the rest of the formula

[0003] means that the two bonds marked with * below each originate from a different carbon atom of the right benzene ring in the remainder of the formula shown above, where the two carbon atoms to which the two bonds marked with * are attached are adjacent to each other in the benzene ring. X 1 becomes part of a five-membered ring. According to the application, no further restrictions are to be derived from the above definition. In particular, the fact that X 1 In formula (G) it should not be deduced that only embodiments of the type shown below according to formulas (G-1), (G-3) and (G-5) are included. On the contrary, all six geometrically possible connection variants of the group , as representatively shown below in formulas (G-1) to (G-6), are encompassed by formula (G) of the present application. This definition also applies to all sub-formulae of formula (G) and formula (I) shown below. It follows that formula (G) encompasses the following alternative embodiments:

[0004]

[0005] which are otherwise each defined as formula (G) above. Among the alternative embodiments of formula (G), formula (G-1) is preferred. The following definitions apply to the chemical groups used in the present application. They apply unless more specific definitions are given. An aryl group in the sense of this invention is understood to mean either a single aromatic cycle, i.e., benzene, or a condensed aromatic polycycle, for example, naphthalene, phenanthrene, or anthracene. A condensed aromatic polycycle in the sense of the present application consists of two or more individual aromatic cycles condensed together. Condensation between cycles is understood to mean that the cycles share at least one edge. An aryl group in the sense of this invention contains 6 to 40 aromatic ring atoms. Furthermore, an aryl group does not contain a heteroatom as an aromatic ring atom.but only carbon atoms. A heteroaryl group in the sense of this invention is understood to be either a single heteroaromatic cycle, for example pyridine, pyrimidine or thiophene, or a condensed heteroaromatic polycycle, for example quinoline or carbazole. A condensed heteroaromatic polycycle in the sense of the present application consists of two or more individual aromatic or heteroaromatic cycles condensed together, where at least one of the aromatic and heteroaromatic cycles is a heteroaromatic cycle. Condensation between cycles is understood to mean that the cycles share at least one edge. A heteroaryl group in the sense of this invention contains 5 to 40 aromatic ring atoms, of which at least one is a heteroatom. The heteroatoms of the heteroaryl group are preferably selected from N, O and S. An aryl or heteroaryl group,which may be substituted with the above-mentioned radicals are understood in particular to mean groups which are derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, triphenylene, fluoranthene, benzanthracene, benzphenanthrene, 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, benzimidazolo[1,2- a]benzimidazole, naphthimidazole, Phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, oxazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, pyrazine, Phenazine, naphthyridine, azacarbazole, benzocarboline,Phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole. An aromatic ring system within the meaning of this invention is a system that does not necessarily contain only aryl groups, but may additionally contain one or more non-aromatic rings fused with at least one aryl group. These non-aromatic rings contain exclusively carbon atoms as ring atoms. Examples of groups encompassed by this definition are tetrahydronaphthalene, fluorene, and spirobifluorene. Furthermore, the term aromatic ring system encompasses systems consisting of two or more aromatic ring systems.which are linked to one another via single bonds, for example biphenyl, terphenyl, 7-phenyl-2-fluorenyl, quaterphenyl, and 3,5-diphenyl-1-phenyl. An aromatic ring system within the meaning of this invention contains 6 to 40 C atoms and no heteroatoms in the ring system. The definition of "aromatic ring system" does not include heteroaryl groups. A heteroaromatic ring system corresponds to the above definition of an aromatic ring system, with the difference that it must contain at least one heteroatom as a ring atom. As is the case with the aromatic ring system, the heteroaromatic ring system does not have to contain exclusively aryl groups and heteroaryl groups, but can additionally contain one or more non-aromatic rings that are fused with at least one aryl or heteroaryl group. The non-aromatic rings can contain exclusively C atoms as ring atoms, or they can additionally contain one or more heteroatoms.wherein the heteroatoms are preferably selected from N, O, and S. An example of such a heteroaromatic ring system is benzopyranyl. Furthermore, the term "heteroaromatic ring system" refers to systems consisting of two or more aromatic or heteroaromatic ring systems linked to one another via single bonds, such as, for example, 4,6-diphenyl-2-triazinyl. A heteroaromatic ring system within the meaning of this invention contains 5 to 40 ring atoms selected from carbon and heteroatoms, wherein at least one of the ring atoms is a heteroatom. The heteroatoms of the heteroaromatic ring system are preferably selected from N, O, and S. The terms "heteroaromatic ring system" and "aromatic ring system" as defined in the present application thus differ from one another in that an aromatic ring system cannot have a heteroatom as a ring atom.whereas a heteroaromatic ring system must have at least one heteroatom as a ring atom. This heteroatom can be present as a ring atom of a non-aromatic heterocyclic ring or as a ring atom of an aromatic heterocyclic ring. According to the above definitions, any aryl group is encompassed by the term "aromatic ring system," and any heteroaryl group is encompassed by the term "heteroaromatic ring system." An aromatic ring system with 6 to 40 aromatic ring atoms or a heteroaromatic ring system with 5 to 40 aromatic ring atoms is understood to mean, in particular, groups derived from the groups mentioned above under aryl groups and heteroaryl groups, as well as from biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, indenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, indenocarbazole,or combinations of these groups. In the context of the present invention, a straight-chain alkyl group having 1 to 20 C atoms or a branched or cyclic alkyl group having 3 to 20 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms, in which individual H atoms or CH2 groups can also be substituted by the groups mentioned above in the definition of the radicals, preferably the radicals methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, neo-pentyl, n-hexyl, cyclohexyl, neo-hexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl, trifluoromethyl, Pentafluoroethyl, 2,2,2-trifluoroethyl, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl, butynyl, pentinyl, hexynyl or octynyl. Under an alkoxy or thioalkyl group with 1 to 20 carbon atoms,in der auch einzelne H-Atome oder CH2-Gruppen durch die oben bei der Definition der Reste genannten Gruppen substituiert sein können, werden bevorzugt Methoxy, Trifluormethoxy, Ethoxy, n-Propoxy, i-Propoxy, n- Butoxy, i-Butoxy, s-Butoxy, t-Butoxy, n-Pentoxy, s-Pentoxy, 2-Methyl- butoxy, n-Hexoxy, Cyclohexyloxy, n-Heptoxy, Cycloheptyloxy, n-Octyloxy, Cyclooctyloxy, 2-Ethylhexyloxy, Pentafluorethoxy, 2,2,2-Trifluorethoxy, Methylthio, Ethylthio, n-Propylthio, i-Propylthio, n-Butylthio, i-Butylthio, s- Butylthio, t-Butylthio, n-Pentylthio, s-Pentylthio, n-Hexylthio, Cyclohexylthio, n-Heptylthio, Cycloheptylthio, n-Octylthio, Cyclooctylthio, 2-Ethylhexylthio, Trifluormethylthio, Pentafluorethylthio, 2,2,2-Trifluorethylthio, Ethenylthio, Propenylthio, Butenylthio, Pentenylthio, Cyclopentenylthio, Hexenylthio, Cyclohexenylthio, Heptenylthio, Cycloheptenylthio, Octenylthio, Cyclooctenylthio, Ethinylthio, Propinylthio, Butinylthio, Pentinylthio, Hexinylthio,Heptynylthio or octynylthio. The phrase "two or more residues can form a ring with each other" is understood in the context of the present application to mean, among other things, that the two residues are linked to each other by a chemical bond. Furthermore, the above phrase is also understood to mean that if one of the two residues is hydrogen, the second residue binds to the position to which the hydrogen atom was bonded, forming a ring. According to a preferred embodiment, X, 1 equal to O. According to a preferred embodiment, X 2 and X 3 each equal to C(R 2 )2. According to a particularly preferred embodiment, X 1 equals O, and X 2 and X 3 are each equal to C(R 2 )2. Ar L is preferably selected from aromatic ring systems with 6 to 25 aromatic ring atoms, which are substituted by radicals R3 are substituted, and particularly preferably selected from phenyl, biphenyl, naphthyl and fluorenyl, which are substituted with radicals R 3 are substituted; and most preferably selected from phenyl which is substituted with radicals R 3 is substituted. Ar L is preferably chosen the same or different at each occurrence from 5 10 15 20 25 30 5 10 15 20 25 30

[0006] 10 15 20 25 30 5 10 15 20 25 30

[0007] where the dashed lines represent the bonds to the remainder of the formula. According to a preferred embodiment, the index n = 0. According to an alternative preferred embodiment, the index n = 1. Ar 1 and Ar 2 are selected, identically or differently at each occurrence, from aromatic ring systems having 6 to 25 aromatic ring atoms, which are substituted by radicals R 4are substituted, and heteroaromatic ring systems with 5 to 25 aromatic ring atoms, which are substituted with radicals R 4 are substituted. Ar 1 and Ar 2 are preferably selected identically or differently from the following formulas:

[0008] where the dashed line represents the bond to the nitrogen atom and where the groups at the unsubstituted positions are bonded to residues R 4 may be substituted, and preferably have only H in the unsubstituted positions shown. Some of the groups shown Ar-1 to Ar-276 also contain one or more residues R 4 . It is preferred that at least one of the groups Ar 1 and Ar 2is an aromatic ring system with at least 12 aromatic ring atoms, which is substituted by radicals R 4 is substituted. According to a preferred embodiment, Ar 1 and Ar 2 not connected to each other by a bond or a group E. R 1 is preferably selected at each occurrence, identically or differently, from H, D, F, CN, Si(R 5 )3, N(R 5 )2, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; and wherein in said alkyl groups one or more CH2 groups are substituted by -C≡C-, -R 5 C=CR 5 -, Si(R 5 )2, C=O, C=NR 5 , -NR5 -, -O-, -S-, -C(=O)O- or -C(=O)NR 5 - may be replaced. R is particularly preferred 1 at each occurrence, identically or differently selected from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where said alkyl groups, said aromatic ring systems and said heteroaromatic ring systems are each substituted by radicals R 5 are substituted. Most preferably R 1 equal to H. R 2is preferably selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 2 may be linked to one another and form a ring; wherein said alkyl groups, said aromatic ring systems and said heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein in said alkyl groups one or more CH2 groups are substituted by -C≡C-, -R 5 C=CR 5 -, Si(R 5 )2, C=O, C=NR 5 , -NR 5 -, -O-, -S-, -C(=O)O- or -C(=O)NR 5 - may be replaced. R is particularly preferred 2at each occurrence, identically or differently selected from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2. R is most preferably 2 at each occurrence, identically or differently selected from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms. Most preferably, R 2 equals methyl. R 3is preferably selected at each occurrence, identically or differently, from H, D, F, CN, Si(R 5 )3, N(R 5 )2, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; and wherein in said alkyl groups one or more CH2 groups are substituted by -C≡C-, -R 5 C=CR 5 -, Si(R 5 )2, C=O, C=NR 5 , -NR 5 -, -O-, -S-, -C(=O)O- or -C(=O)NR 5 - may be replaced. R is particularly preferred 3at each occurrence, identically or differently selected from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where said alkyl groups, said aromatic ring systems and said heteroaromatic ring systems are each substituted by radicals R 5 are substituted. R 4 is preferably selected at each occurrence, identically or differently, from H, D, F, CN, Si(R 5 )3, N(R 5)2, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; and wherein in said alkyl groups one or more CH2 groups are substituted by -C≡C-, -R 5 C=CR 5 -, Si(R 5 )2, C=O, C=NR 5 , -NR 5 -, -O-, -S-, -C(=O)O- or -C(=O)NR 5 - may be replaced. R is particularly preferred 4at each occurrence, identically or differently selected from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where said alkyl groups, said aromatic ring systems and said heteroaromatic ring systems are each substituted by radicals R 5 are substituted. R 5 is preferably selected at each occurrence, identically or differently, from H, D, F, CN, Si(R 6 )3, N(R 6)2, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 6 are substituted; and wherein in said alkyl groups one or more CH2 groups are substituted by -C≡C-, -R 6 C=CR 6 -, Si(R 6 )2, C=O, C=NR 6 , -NR 6 -, -O-, -S-, -C(=O)O- or -C(=O)NR 6 - may be replaced. R is particularly preferred 5at each occurrence, identically or differently selected from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where said alkyl groups, said aromatic ring systems and said heteroaromatic ring systems are each substituted by radicals R 6 are substituted. R 6 is preferably equal to H. Preferred embodiments of formulas (G-1) to (G-6) are shown below:

[0009] which are otherwise defined as formula (G) above. Among the formulas, formulas (G-1-1) and (G-1-2) are particularly preferred, especially formula (G-1-1). Preferred embodiments of formula (I) correspond to the following formulas:

[0010] where the groups occurring are defined as above. Particularly preferred is X 2 and X 3 each equal to C(R 2 )2. X is particularly preferred 1 equal to O. Preferred embodiments of formulas (I-1) to (I-4) correspond to the following formulas:

[0011] where the groups occurring are defined as above. Particularly preferred is X 2 and X 3 each equal to C(R 2 )2. X is particularly preferred 1 is equal to O. According to a preferred embodiment, formula (I) corresponds to one of the formulas (I-1) and (I-3), in particular formula (I-1). According to a particularly preferred embodiment, formula (I) corresponds to one of the formulas (I-1-A) and (I-3-A), in particular formula (I-1-A). Preferred embodiments of formula (I-1) correspond to the

[0012] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formula (I-1-1) is particularly preferred.

[0013] Particularly preferred embodiments of formulas (I-1-1) to (I-1-4) are the following formulas:

[0014] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formula (I-1-1-A) is particularly preferred.

[0015] Preferred embodiments of formula (I-2) correspond to the following formulas:

[0016] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formulas (I-2-1), (I-2-3), and (I-2-4) are particularly preferred. Particularly preferred embodiments of formulas (I-2-1) to (I-2-4) are the following formulas:

[0017] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formula (I-2-1-A) is particularly preferred. Preferred embodiments of formula (I-3) correspond to the following formulas:

[0018] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Particularly preferred embodiments of formulas (I-3-1) and (I-3-2) correspond to the following formulas:

[0019] ( ), where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Preferred embodiments of formula (I-4) correspond to the following formulas:

[0020] where the variables appearing are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formulas (I-4-1), (I-4-2), and (I-4-4) are particularly preferred. Formula (I-4-1) is very particularly preferred. According to an alternative preferred embodiment, formula (I) corresponds to formula (I-4-3). Preferred embodiments of formulas (I-4-1) to (I-4-4) correspond to the following formulas:

[0021] where the variables occurring are as defined above and preferably correspond to their preferred embodiments given above. Among the formulas, formulas (I-4-1-A), (I-4-2-A) and (I-4-4-A) are particularly preferred, and formula (I-4-1-A) is very particularly preferred. According to an alternative preferred embodiment, formula (I) corresponds to formula (I-4-3-A). According to a preferred embodiment, formula (I) corresponds to one of the formulas (I-1-1), (I-1-2), (I-1-3), (I-1-4), (I-3-1), (I-3-2), (I-4-1), (I-4-2) and (I-4-4). Among the formulas mentioned, the preferred embodiments according to formulas (I-1-1-A), (I-1-2-A), (I-1-3-A), (I-1-4-A), (I-3-1-A), (I-3-2-A), (I-4-1-A), (I-4-2-A) and (I-4-4-A) are each preferred. According to an alternative preferred embodiment, formula (I) corresponds to one of formulas (I-2-1) and (I-2-2), in particular formulas (I-2-1-A) and (I-2-2-A).According to a preferred embodiment, formula (I) corresponds to one of the formulas (I-1-1), (I-1-2), (I-1-3), (I-1-4), (I-3-1), (I-3-2). Among the formulas mentioned, the preferred embodiments according to formulas (I-1-1-A), (I-1-2-A), (I-1-3-A), (I-1-4-A), (I-3-1-A), (I-3-2-A) are each preferred. According to a preferred embodiment, formula (I) corresponds to one of the formulas (I-4-1), (I-4-2) and (I-4-4), with formula (I-4-1) being preferred, in particular to a formula (I-4-1-A), (I-4-2-A) and (I-4-4-A), with formula (I-4-1-A) being preferred, and wherein at least one of the conditions a) and b) applies: a) R. 2 is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; b) index n is 1. According to a preferred embodiment, both of conditions a) and b) apply. According to an alternative preferred embodiment, formula (I) corresponds to formula (I-4-3), in particular to formula (I-4-3-A), where at least one of conditions a) and b) is present: a) R 2 is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5), -O-, -S-, SO or SO2; b) index n is equal to 1. According to a preferred embodiment, both of conditions a) and b) are met. Such compounds are particularly well suited for use in a hole-transporting layer, which in the terminology of the person skilled in the art is also referred to as a "common layer", and which does not directly border the emitting layer, but which borders on the anode side on another hole-transporting layer, which in turn borders on the anode side on the emitting layer. According to a preferred embodiment of formula (I), the following definitions of the variables are present in combination with one another: G is a group according to formula (G) which is bonded to the radical of formula (I) via one of the free positions on the benzene rings, where the further free positions on the benzene rings are each bonded to a radical R 1 are substituted; X 1 is O or S; X 2 is C(R 2 )2; X3 is C(R 2 )2; Ar L is selected from phenyl, biphenyl, naphthyl and fluorenyl, each with residues R 3 are substituted; Ar 1 , Ar 2 is, identically or differently, an aromatic ring system with 6 to 40 aromatic ring atoms, which is substituted with radicals R 4 substituted, or a heteroaromatic ring system with 5 to 25 aromatic ring atoms, which is substituted with radicals R 4 is substituted; R 1 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; R 2is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; R 3 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; R 4is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; R 5 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 6are substituted, and where radicals R 6 are H; n is 0 or 1. The present application also relates to a compound of formula (I) as defined above, wherein, deviating from the above definition for R 2 applies: R 2 is selected, identically or differently, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5), -O-, -S-, SO or SO2; preferably identically or differently selected from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; particularly preferably methyl. All other substance-related definitions given above in connection with formula (I) are also preferred. The compound of formula (I) with this definition of the variable R 2 According to the application, it can be used generally in electronic devices, especially OLEDs, without the above-mentioned restriction of mandatory use in a layer between the anode and the emitting layer. The following compounds are preferred embodiments of compounds of formula (I):

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] The compounds of formula (I) can be prepared using the synthesis processes described below. The skilled person can modify these within the scope of their general technical knowledge to prepare further compounds according to the application that cannot be directly prepared by the processes shown below. The compounds of formula (I) can be prepared by various synthesis routes, which are explained in more detail below. According to a first variant (Scheme 1), a benzene derivative containing two carboxylic acid ester groups, a dibenzofuran or dibenzothiophene group, and a halogen atom as substituents is coupled with a benzene derivative containing an amino group and a boronic acid as substituents in a Suzuki reaction (a). Subsequently, an organometallic compound is added to the carbonyl group of the carboxylic ester groups, preferably an organometallic compound in a Grignard reaction (b).In this process, tertiary alcohol groups are formed on the benzene rings. These are then cyclized under acidic conditions to form the indenofluorenyl structure (c). Scheme 1. X is equal to O or S, Ar L and n, as well as Ar 1 and Ar 2 are as defined above. Hal is Cl, Br or I, preferably Cl. R is an organic residue. According to a second variant (Scheme 2), steps a) to c) are carried out as shown above in Scheme 1, except that halogen-substituted phenyl is used in step a) instead of amine-substituted phenyl. Subsequently, in step d), a Suzuki coupling reaction with a group Ar 1 Ar 2 N-Ar L -B(OR)2or a Buchwald coupling reaction with a group Ar 1 Ar 2 NH (d)). Scheme 2 X is equal to O or S, Ar L and n, as well as Ar 1 and Ar 2are as defined above. Hal is Cl, Br or I, preferably Cl. R is an organic residue. According to a third variant (Scheme 3), steps a) to c) are carried out as shown above in Scheme 1, except that unsubstituted phenyl is used in step a) instead of amine-substituted phenyl. Following step c), a borylation (d)) is carried out, followed by a Suzuki coupling with a compound Ar 1 Ar 2 N-Ar L -Hal (e)). Scheme 3

[0029] X, Ar L and n, as well as Ar 1 and Ar 2are as defined above. Hal is Cl, Br or I, preferably Cl. R is an organic radical. To prepare compounds corresponding to the preferred embodiments of formula (I), according to one of the formulas (I-3), (I-3-A), (I-3-1), (I-3-2), (I-3-1-A) and (I-3-2-A), in which the amino group is bonded to the middle benzene ring of the indenofluorene, an alternative variant 4 for the synthesis is preferably used (Scheme 4). For this purpose, a fluorenyl derivative bearing two halogen atoms on one of its benzene rings is used. This is reacted (step a)) in a Suzuki or Buchwald reaction with a compound Ar 1 Ar 2 N-Ar L -B(OR)2 or Ar 1 Ar 2NH, and then a boronic acid group is introduced. Then, in step b), a Suzuki reaction is carried out on the boronic acid group with a dibenzothiophene or dibenzofuran derivative bearing a carboxylic acid ester group. A metal organyl is added to this group as in steps b) and c) of Schemes 1 to 3, and an acid-catalyzed ring closure reaction is carried out, yielding the compound of formula (I) (steps c) and d)). Scheme 4

[0030] X, Ar L and n, as well as Ar 1 and Ar 2are as defined above. Hal is Cl, Br, or I, preferably Cl. R is an organic radical. The skilled person can use the processes described above to obtain compounds of formula (I). Alternatively, he can also adapt, modify, and optimize the processes within the scope of his general expert knowledge, as necessary, to prepare compounds of formula (I). The compounds shown above can each be substituted with organic radicals at their unsubstituted positions.The present application therefore relates to a process for preparing a compound of formula (I), characterized in that at least one sequence of process steps a) followed by b) is present, wherein process step a) comprises a reaction in which a carboxylic acid ester group which binds to a biphenyl unit in the ortho position to the bond between the two benzene rings of the biphenyl unit is converted into a tertiary alcohol group by addition of a metal organyl, preferably a Grignard reagent, and wherein process step b) comprises a reaction in which the tertiary alcohol group obtained in process step a) undergoes a ring closure reaction under acidic conditions, in particular acidic ion exchange resin, such as Amberlyst-15, so that a fluorenyl unit is formed from the biphenyl unit. The process preferably comprises further steps selected from Suzuki coupling, Buchwald coupling and borylation.The compounds of formula (I) described above, in particular compounds substituted by reactive leaving groups such as bromine, iodine, chlorine, boronic acid or boronic esters, can be used as monomers to produce corresponding oligomers, dendrimers or polymers. Suitable reactive leaving groups are, for example, bromine, iodine, chlorine, boronic acids, boronic esters, amines, alkenyl or alkynyl groups with a terminal CC double bond or CC triple bond, oxiranes, oxetanes, groups that undergo cycloaddition, for example a 1,3-dipolar cycloaddition, such as dienes or azides, carboxylic acid derivatives, alcohols and silanes. The invention therefore further provides oligomers, polymers or dendrimers comprising one or more compounds of formula (I), wherein the bond(s) to the polymer, oligomer or dendrimer are at any desired positions designated by R in formula (I). 1 , R 2 , R 3 , or R 4substituted positions. Depending on the linkage of the compound according to formula (I), the compound is part of a side chain of the oligomer or polymer or part of the main chain. Further disclosure concerning oligomers, polymers, or dendrimers can be found on page 49, line 26 - page 51, line 17 of WO 2020 / 109434 A1. The disclosure of these passages is hereby incorporated in its entirety by citation into the present application. For processing the compounds according to the invention from the liquid phase, for example by spin coating or by printing processes, formulations of the compounds according to the invention are required. These formulations can be, for example, solutions, dispersions, or emulsions. It may be preferable to use mixtures of two or more solvents for this purpose. Suitable and preferred solvents are, for example, toluene, anisole, o-, m-, or p-xylene, methyl benzoate, mesitylene, tetralin, veratrole, THF,Methyl-THF, THP, chlorobenzene, dioxane, phenoxytoluene, in particular 3-phenoxytoluene, (-)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol, 2-pyrrolidinone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, acetophenone, alpha-terpineol, benzothiazole, butyl benzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene, decalin, dodecylbenzene, ethyl benzoate, indane, methyl benzoate, NMP, p-cymene, phenetol, 1,4-diisopropylbenzene, dibenzyl ether, Diethylene glycol butylmethyl ether, triethylene glycol butylmethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane or mixtures of these solvents. The invention therefore further relates to a formulation, in particular a solution,A dispersion or emulsion comprising at least one compound of formula (I) or at least one polymer, oligomer, or dendrimer comprising at least one unit of formula (I), and at least one solvent, preferably an organic solvent. The preparation of such solutions is known to the person skilled in the art. The use of the compound of formula (I) according to the application is described below: The compound of formula (I) is suitable for use in an electronic device, in particular an organic electroluminescent device (OLED). Depending on the substitution, the compound of formula (I) can be used in different functions and layers. Preference is given to use as a hole-transporting material in a hole-transporting layer and / or as a matrix material in an emitting layer.particularly preferably in combination with a phosphorescent emitter. The invention therefore further relates to the use of a compound according to formula (I) in an electronic device. The electronic device is preferably selected from the group consisting of 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 particularly preferably organic electroluminescent devices (OLEDs). The invention further relates to an electronic device,containing at least one compound according to formula (I). The electronic device is preferably selected from the above-mentioned devices. Particular preference is given to an organic electroluminescent device containing an anode, a cathode, and at least one emitting layer, characterized in that at least one organic layer is contained in the device which contains at least one compound according to formula (I). Preferred is an organic electroluminescent device containing an anode, a cathode, and at least one emitting layer, characterized in that at least one organic layer in the device, selected from hole-transporting and emitting layers, contains at least one compound according to formula (I). A hole-transporting layer is understood to mean all layers that are arranged between the anode and the emitting layer, preferably a hole injection layer, a hole transport layer,and electron blocking layer. A hole injection layer is understood to be a layer that directly borders the anode. A hole transport layer is understood to be a layer that is present between the anode and the emitting layer, but not directly borders the anode, and preferably not directly borders the emitting layer either. An electron blocking layer is understood to be a layer that is present between the anode and the emitting layer and directly borders the emitting layer. An electron blocking layer preferably has a high-energy LUMO and thus prevents electrons from escaping from the emitting layer. In addition to the cathode, anode, and emitting layer, the electronic device can contain further layers. These are selected, for example, from one or more hole injection layers, hole transport layers, hole blocking layers, electron transport layers,Electron injection layers, electron blocking layers, exciton blocking layers, interlayers, charge generation layers, and / or organic or inorganic p / n junctions. It should be noted, however, that not all of these layers necessarily need to be present, and the choice of layers always depends on the compounds used and, in particular, on whether the device is fluorescent or phosphorescent. The sequence of layers of the electronic device is preferably as follows: -anode- -hole injection layer- -hole transport layer- -optional further hole transport layers- -emitting layer- -optional hole blocking layer- -electron transport layer- -electron injection layer- -cathode-. It should be noted again that not all of the aforementioned layers need to be present.and / or that additional layers may be present. The organic electroluminescent device according to the invention can contain a plurality of emitting layers. Particularly preferably, these emitting layers have a total of several emission maxima between 380 nm and 750 nm, resulting in overall white emission, i.e., various emitting compounds that can fluoresce or phosphoresce and that emit blue, green, yellow, orange, or red light are used in the emitting layers. Particular preference is given to three-layer systems, i.e., systems with three emitting layers, wherein one of the three layers exhibits blue emission, one of the three layers exhibits green emission, and one of the three layers exhibits orange or red emission. The compounds according to the invention are preferably present in a hole-transporting layer or in the emitting layer. It should be noted thatthat for the generation of white light, instead of several color-emitting emitter compounds, a single emitter compound which emits in a broad wavelength range can also be suitable. It is preferred that the compound of formula (I) is used as the hole-transport material. The emitting layer can be a fluorescent emitting layer or it can be a phosphorescent emitting layer. The emitting layer is preferably a blue fluorescent layer or a green phosphorescent layer. If the device comprising the compound of formula (I) contains a phosphorescent emitting layer, it is preferred that this layer has two or more, preferably exactly two,contains various matrix materials (mixed matrix system). Preferred embodiments of mixed matrix systems are described in more detail below. If the compound according to formula (I) is used as a hole-transport material in a hole-transport layer, a hole-injection layer, or an electron-blocking layer, the compound can be used as a pure material, i.e., in a proportion of 100%, in the hole-transport layer, or it can be used in combination with one or more further compounds. According to a preferred embodiment, a hole-transporting layer comprising the compound of formula (I) additionally contains one or more further hole-transporting compounds. These further hole-transporting compounds are preferably selected from triarylamine compounds,particularly preferably from mono-triarylamine compounds. They are most preferably selected from the preferred embodiments of hole-transporting materials specified below. In the preferred embodiment described, the compound of formula (I) and the one or more further hole-transporting compounds are preferably each present in a proportion of at least 10%, particularly preferably each present in a proportion of at least 20%. According to a preferred embodiment, a hole-transporting layer comprising the compound of formula (I) additionally contains one or more p-dopants. According to the present invention, p-dopants are preferably those organic electron acceptor compounds which can oxidize one or more of the other compounds of the mixture. Particularly preferred p-dopants are quinodimethane compounds, azaindenofluorenediones, azaphenalenes, azatriphenylenes, I2, metal halides,Preferably, transition metal halides, metal oxides, preferably metal oxides containing at least one transition metal or a metal of main group 3, and transition metal complexes, preferably complexes of Cu, Co, Ni, Pd, and Pt with ligands containing at least one oxygen atom as a bonding site. Also preferred are transition metal oxides as dopants, preferably oxides of rhenium, molybdenum, and tungsten, particularly preferably Re2O7, MoO3, WO3, and ReO3. Even more preferred are complexes of bismuth in the oxidation state (III), in particular bismuth(III) complexes with electron-deficient ligands.in particular carboxylate ligands. The p-dopants are preferably largely uniformly distributed in the p-doped layers. This can be achieved, for example, by co-evaporation of the p-dopant and the hole-transport material matrix. The p-dopant is preferably present in a proportion of 1 to 10% in the p-doped layer. Furthermore, preferred p-dopants are the compounds explicitly depicted on pages 86-87 of published patent application WO2021 / 156323A1. According to a preferred embodiment, a hole-injection layer is present in the device, which corresponds to one of the following embodiments: a) it contains a triarylamine and a p-dopant; or b) it contains a single electron-deficient material (electron acceptor). According to a preferred embodiment of embodiment a), the triarylamine is a mono-triarylamine,in particular one of the preferred triarylamine derivatives mentioned below. According to a preferred embodiment of embodiment b), the electron-poor material is a hexaazatriphenylene derivative, as described in US 2007 / 0092755. The compound of formula (I) can be present in a hole-injection layer, in a hole-transport layer, and / or in an electron-blocking layer of the device. If the compound is present in a hole-injection layer or in a hole-transport layer, it is preferably p-doped, i.e., it is present in the layer mixed with a p-dopant, as described above. The compound of formula (I) is preferably present in an electron-blocking layer. In this case, it is preferably not p-doped. Furthermore, in this case, it is preferably present as a single compound in the layer.without admixture of another compound. According to an alternative preferred embodiment, the compound of formula (I) is used in an emitting layer as a matrix material in combination with one or more emitting compounds, preferably phosphorescent emitting compounds. The phosphorescent emitting compounds are preferably selected from red phosphorescent and green phosphorescent compounds. The proportion of matrix material in the emitting layer in this case is between 50.0 and 99.9 vol.%, preferably between 80.0 and 99.5 vol.%, and particularly preferably between 85.0 and 97.0 vol.%. Accordingly, the proportion of the emitting compound is between 0.1 and 50.0 vol.%.preferably between 0.5 and 20.0 vol.% and particularly preferably between 3.0 and 15.0 vol.%. An emitting layer of an organic electroluminescent device can also contain systems comprising several matrix materials (mixed-matrix systems) and / or several emitting compounds. In this case, too, the emitting compounds are generally those compounds whose proportion in the system is the smaller, and the matrix materials are those compounds whose proportion in the system is the larger. In individual cases, however, the proportion of an individual matrix material in the system can be smaller than the proportion of an individual emitting compound. It is preferred that the compounds according to formula (I) are used as a component of mixed-matrix systems, preferably for phosphorescent emitters. The mixed-matrix systems preferably comprise two or three different matrix materials,Particularly preferably, two different matrix materials are used. One of the two materials is preferably a material with hole-transporting properties and the other material is a material with electron-transporting properties. It is further preferred if one of the materials is selected from compounds with a large energy difference between HOMO and LUMO (wide-bandgap materials). The compound of formula (I) in a mixed-matrix system preferably represents the matrix material with hole-transporting properties. Accordingly, if the compound of formula (I) is used as a matrix material for a phosphorescent emitter in the emitting layer of an OLED, a second matrix compound is present in the emitting layer which has electron-transporting properties. The two different matrix materials can be used 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. According to a preferred embodiment, in the case of mixed-matrix systems, the two or more matrix materials contained in the mixed-matrix system, at least one of which preferably corresponds to formula (I), are used as a mixture and applied by evaporation. However, the desired electron-transporting and hole-transporting properties of the mixed-matrix components can also be combined mainly or completely in a single mixed-matrix component, with the additional mixed-matrix component(s) fulfilling other functions. The following material classes are preferably used in the above-mentioned layers of the device: Phosphorescent emitters: The term phosphorescent emitters typically encompasses compounds in which light emission occurs through a spin-forbidden transition.for example, a transition from an excited triplet state or a state with a higher spin quantum number, for example, a quintet state. Particularly suitable phosphorescent emitters are compounds that, upon suitable excitation, emit light, preferably in the visible range, and also contain at least one atom with an atomic number greater than 20, preferably greater than 38 and less than 84, particularly preferably greater than 56 and less than 80. Preferably, compounds containing copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold, or europium are used as phosphorescent emitters, in particular compounds containing iridium, platinum, or copper. For the purposes of the present invention, all luminescent iridium, platinum, or copper complexes are considered phosphorescent compounds. In general, all phosphorescent complexes are suitable.as used in the prior art for phosphorescent OLEDs and as known to those skilled in the art in the field of organic electroluminescent devices, for use in the devices according to the invention. Further examples of suitable phosphorescent emitters are shown in the following table:

[0031] Fluorescent emitters: Preferred fluorescent emitting compounds are selected from the class of arylamines. An arylamine or an aromatic amine within the meaning of this invention is understood to be a compound 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, particularly preferably with at least 14 aromatic ring atoms. Preferred examples are aromatic anthraceneamines, aromatic anthracenediamines, aromatic pyreneamines, aromatic pyrenediamines, aromatic chryseneamines, or aromatic chrysenediamines. An aromatic anthraceneamine is understood to be a compound in which a diarylamino group is bonded directly to an anthracene group, preferably in the 9-position.An aromatic anthracenediamine is understood to be 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, with the diarylamino groups on the pyrene preferably being bonded in the 1-position or 1,6-position, respectively. Further preferred emitting compounds are indenofluorenamines and diamines, benzoindenofluorenamines and diamines, and dibenzoindenofluorenamines and diamines, as well as indenofluorene derivatives with fused aryl groups. Pyrene-arylamines are also preferred. Also preferred are benzoindenofluoreneamines, benzofluoreneamines, extended benzoindenofluorenes, phenoxazines, and fluorene derivatives bonded to furan units or thiophene units.Matrix materials for fluorescent emitters: Preferred matrix materials for fluorescent emitters are selected from the classes of oligoarylenes (e.g., 2,2',7,7'-tetraphenylspirobifluorene), in particular oligoarylenes containing condensed aromatic groups, oligoarylenevinylenes, polypodal metal complexes, hole-conducting compounds, electron-conducting compounds, in particular ketones, phosphine oxides, and sulfoxides; atropisomers, boronic acid derivatives, or benzanthracenes. Particularly preferred matrix materials are selected from the classes of oligoarylenes containing naphthalene, anthracene, benzanthracene, and / or pyrene or atropisomers of these compounds, oligoarylenevinylenes, ketones, phosphine oxides, and sulfoxides. Very particularly preferred matrix materials are selected from the classes of oligoarylenes containing anthracene, benzanthracene, benzphenanthrene and / or pyrene or atropisomers of these compounds.An oligoarylene, within the meaning of this invention, is understood to mean a compound in which at least three aryl or arylene groups are bonded to one another. Matrix materials for phosphorescent emitters: In addition to the compounds of formula (I), preferred matrix materials for phosphorescent emitters are aromatic ketones, aromatic phosphine oxides or aromatic sulfoxides or sulfones, triarylamines, carbazole derivatives, e.g., CBP (N,N-biscarbazolylbiphenyl) or carbazole derivatives, indolocarbazole derivatives, indenocarbazole derivatives, azacarbazole derivatives, bipolar matrix materials, silanes, azaboroles or boronic esters, triazine derivatives, zinc complexes, diazasilole or tetraazasilole derivatives, diazaphosphole derivatives, bridged carbazole derivatives, triphenylene derivatives, or lactams. Electron-transporting materials: Suitable electron-transporting materials include those described in Y. Shirota et al., Chem. Rev.2007, 107(4), 953-1010, or other materials as used in these layers according to the prior art. All materials that are used in the prior art as electron-transport materials in the electron-transport layer can be used as materials for the electron-transport layer. Particularly suitable are aluminum complexes, for example Alq3; zirconium complexes, for example Zrq4; lithium complexes, for example Liq; benzimidazole derivatives, triazine derivatives, pyrimidine derivatives, pyridine derivatives, pyrazine derivatives, quinoxaline derivatives, quinoline derivatives, oxadiazole derivatives, aromatic ketones, lactams, boranes, diazaphosphole derivatives, and phosphine oxide derivatives. Preferred electron-transport and electron-injection materials are also the compounds explicitly shown on pages 73-75 of WO2020 / 109434A1.Hole-transporting materials: Further compounds which, in addition to the compounds of formula (I), are preferably used in hole-transporting layers of the OLEDs according to the invention are indenofluorenamine derivatives, amine derivatives, hexaazatriphenylene derivatives, amine derivatives with condensed aromatics, monobenzoindenofluorenamines, dibenzoindenofluorenamines, spirobifluorene amines, fluorene amines, spiro-dibenzopyran amines, dihydroacridine derivatives, spirodibenzofurans and spirodibenzothiophenes, phenanthrene diarylamines, spiro-tribenzotropolones, spirobifluorenes with meta-phenyldiamine groups, spiro-bisacridines, xanthene diarylamines, and 9,10-dihydroanthracene spiro compounds with diarylamino groups. Preferred hole-transporting compounds are also those explicitly depicted on pages 76-80 of WO2020 / 109434A1. The following compounds HT-1 to HT-21 are particularly well suited for use in a layer with a hole-transport function in an OLED.This applies not only to OLEDs according to the definitions and claims of the present application, but to OLEDs in general:.

[0032] The compounds HT-1 to HT-21 can generally be used in any hole-transport layer of OLEDs. The term "hole-transport layer" here refers to any layer of an OLED located between the anode and the emitting layer. The term "OLED" is not specifically restricted and applies to all OLEDs, in particular to the OLED structures common at the time of filing this application. The compounds HT-1 to HT-21 can be prepared by processes disclosed in the application texts listed in the table above under the respective compounds HT-1 to HT-21. The teachings regarding the use of the compounds and the processes for preparing the compounds contained in the above-mentioned application texts are hereby expressly incorporated into the present disclosure by reference.The compounds HT-1 to HT-21 exhibit excellent properties when used in OLEDs, particularly excellent lifetime and efficiency. This is especially the case when used in a hole-transport layer of the OLED. Metals with low work functions, metal alloys, or multilayer structures composed of different metals are preferred as the cathode of the electronic device, such as alkaline earth metals, alkali metals, main group metals, or lanthanides (e.g., Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.). Alloys composed of an alkali or alkaline earth metal and silver, for example, an alloy of magnesium and silver, are also suitable. In multilayer structures, other metals with a relatively high work function, such as Ag or Al, can also be used in addition to the metals mentioned. Combinations of these metals, such as Ca / Ag, Mg / Ag, or Ba / Ag, are then generally used.It may also be preferable to introduce a thin intermediate layer of a material with a high dielectric constant between a metallic cathode and the organic semiconductor. Examples of suitable materials include alkali metal or alkaline earth metal fluorides, but also the corresponding oxides or carbonates (e.g., LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.). Lithium quinolinate (LiQ) can also be used for this purpose. The thickness of this layer is preferably between 0.5 and 5 nm. Materials with a high work function are preferred as the anode. The anode preferably has a work function greater than 4.5 eV vs. vacuum. Metals with a high redox potential, such as Ag, Pt, or Au, are suitable for this purpose. Metal / metal oxide electrodes (e.g., Al / Ni / NiOx, Al / PtOx) may also be preferred.For some applications, at least one of the electrodes must be transparent or partially transparent to enable either the irradiation of the organic material (organic solar cell) or the coupling out of light (OLED, O-LASER). Preferred anode materials here are conductive mixed metal oxides. Indium tin oxide (ITO) or indium zinc oxide (IZO) are particularly preferred. Also preferred are conductive, doped organic materials, in particular conductive doped polymers. Furthermore, the anode can also consist of several layers, for example an inner layer of ITO and an outer layer of a metal oxide, preferably tungsten oxide, molybdenum oxide, or vanadium oxide. In a preferred embodiment, the electronic device is characterized in that one or more layers are coated using a sublimation process. The materials are sublimated in vacuum sublimation systems at an initial pressure of less than 10.-5 mbar, preferably less than 10 -6 mbar. However, it is also possible that the initial pressure is even lower, for example less than 10 -7 mbar. Also preferred is an electronic device characterized in that one or more layers are coated using the OVPD (Organic Vapour Phase Deposition) process or by means of carrier gas sublimation. The materials are deposited at a pressure between 10 -5mbar and 1 bar. A special case of this process is the OVJP (Organic Vapour Jet Printing) process, in which the materials are applied directly through a nozzle and thus structured (e.g. BMS Arnold et al., Appl. Phys. Lett. 2008, 92, 053301). Also preferred is an electronic device characterized in that one or more layers are produced from solution, for example by spin coating, or using any printing process, such as screen printing, flexographic printing, nozzle printing or offset printing, but particularly preferably LITI (Light Induced Thermal Imaging, thermal transfer printing) or inkjet printing. For this purpose, soluble compounds according to formula (I) are required. High solubility can be achieved by suitable substitution of the compounds.It is further preferred that, to produce an electronic device according to the invention, one or more layers are applied from a solution and one or more layers are applied by a sublimation process. After application of the layers, the device is structured, contacted, and finally sealed, depending on the application, to exclude the damaging effects of water and air. According to the invention, the electronic devices comprising one or more compounds according to formula (I) can be used in displays, as light sources in lighting applications, and as light sources in medical and / or cosmetic applications.The electronic device according to the application, comprising an anode, a cathode, an emitting layer, and a layer comprising a compound of formula (I) arranged between the anode and the emitting layer, preferably has one or more of the above-mentioned preferred features relating to electronic devices comprising a compound of formula (I). In particular, with regard to the electronic device according to the application comprising a compound of formula (I), it is preferred that it is an OLED. Furthermore, in particular, with regard to the device, it is preferred that it has a blue-fluorescent emitting layer, and that the compound of formula (I) is present in a hole-transporting layer which, on the anode side, borders another layer which, on the anode side, borders the emitting layer.Alternatively, the device preferably has a blue fluorescent or green phosphorescent emitting layer, and the compound of formula (I) is present in a hole-transporting layer adjacent to the emitting layer on the anode side. Examples A) Synthesis Examples Synthesis of Int-1a.

[0033] 15.4 g (35 mmol) of SM-1, 19.3 g (37 mmol) of BE-1, and 16.0 g (70 mmol) of potassium phosphate monohydrate were initially dissolved in 450 ml of THF / water (2:1). Then, 883 mg (1.0 mmol) of XPhos palladacyle Gen.3 were added, and the mixture was stirred at 60 °C. After complete conversion, the reaction mixture was cooled to room temperature and extracted twice with THF, dried over sodium sulfate, filtered, and concentrated on a rotary evaporator. The residue was filtered through AlOx (heptane / toluene) and then concentrated. The product was obtained as a solid with an HPLC purity of >96% after crystallization from ethyl acetate and isopropanol. Yield: 20.9 g (27 mmol; 77%). The following compounds could be prepared analogously: *The borrelation in the reactions given above proceeds analogously to that of compound EG1 from WO2019 / 170572. Synthesis of Int-2a 13.5 g (55 mmol) of cerium(III) chloride are initially charged, and 20.2 g (27 mmol) of Int-1a dissolved in 300 mL of THF are added and stirred at room temperature for one hour. The reaction mixture is cooled to 0°C, and at this temperature, 51.4 mL (154 mmol) of methylmagnesium chloride (3M in THF) is slowly added dropwise. The reaction mixture is then stirred at room temperature for two hours. After the reaction is complete, saturated aqueous ammonium chloride solution is carefully added. The suspension is diluted with 200 mL of water and extracted three times with 200 mL of THF. The combined organic phases are dried over sodium sulfate, filtered, and concentrated, and the product is obtained as a solid. Yield: 20.4 g (27 mmol; 100%)

[0034] The following connections can be represented in an analogous manner:

[0035] Synthesis of compound 1a 20.2 g (27 mmol) of Int-2a are dissolved in 500 mL of THF and treated with 3.7 g (38 mmol) of Amberlyst-15. The reaction mixture is stirred at 100°C overnight until complete conversion is complete, then filtered and concentrated on a rotary evaporator. The residue is extracted twice with toluene over AlOx and subsequently crystallized several times from toluene / heptane to an HPLC purity of >99.9%. The product is purified after zone sublimation (10 -6 bar, 340°C) as a solid. Yield: 10.1 g (14 mmol; 53%). The following compounds can be prepared analogously:

[0036] *Int-3b-a and Int-3b-b are formed as a mixture of isomers, which can be separated chromatographically. Synthesis of 2a 11.1 g (26 mmol) of Int-3a, 8.85 g (25 mmol) of 9,9-dimethylfluorenyl-2-(4-biphenyl)amine, 3.5 g (37 mmol) of sodium tert-butoxide, and 616 mg (0.73 mmol) of XPhos Pd Gen3 are suspended in 400 ml of toluene and stirred at 100°C for 16 hours. After complete conversion, the reaction mixture is allowed to cool to room temperature, filtered through aluminum oxide, and rinsed with toluene. After removal of the solvents, the crude product is dissolved in toluene / heptane 1:1 and filtered through silica gel. Further purification is carried out by repeated crystallization from heptane / toluene to an HPLC purity of >99.9%. Finally, the product is subjected to two sublimation cycles (310 °C, 10 -6 bar) as a solid. Yield: 7.5 g (10 mmol; 39%). The following compounds can be prepared analogously:

[0037] Synthesis of Int-4 16.2 g (40 mmol) of Int-3d were suspended in 600 mL of THF and cooled to -45°C. 31 mL (43 mmol) of sec-BuLi (1.4M in cyclohexane) were slowly added dropwise. After the addition was complete, the mixture was stirred at -20°C for one hour. The reaction mixture was then cooled to -35°C, and 17.8 mL (80 mmol) of 2-isoproxy-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane were added dropwise. The mixture was stirred at -20°C for 30 minutes. The reaction mixture was allowed to warm to room temperature overnight. 50 mL of saturated aqueous ammonium chloride solution was slowly added to the reaction mixture, and the organic phase was diluted with ethyl acetate. The organic phase was washed twice with 200 mL of water, filtered, and dried over sodium sulfate. The solvents were removed on a rotary evaporator, and the product was obtained as a solid. Yield: 17.5 g (33.4 mmol; 84%). Synthesis of 3a 12.1 g (23 mmol) of Int-4, 11.0 g (23 mmol) of bis-biphenyl-4-yl(4-bromophenyl)amine (CAS 499128-71-1), and 8.8 g (23 mmol) of potassium phosphate monohydrate were suspended in 250 ml of THF / water (4:1). After addition of 483 mg (0.57 mmol) of XPhos Palladacycle Gen3, the reaction mixture was stirred at 60°C overnight until complete conversion. The reaction mixture was allowed to cool to room temperature, and the precipitated solid was filtered and washed with water, isopropanol, and finally with heptane. The residue was extracted four times with toluene over AlOx and crystallized to an HPLC purity of >99.9%. The product was isolated after zone sublimation (10 -6 bar , 360°C) as a solid. The following compounds can be prepared in an analogous manner:

[0038] B) Device examples 1) General manufacturing process for the OLEDs and characterization of the OLEDs Glass plates coated with structured ITO (indium tin oxide) with a thickness of 50 nm form the substrates onto which the OLEDs are applied. The OLEDs basically have the following layer structure: substrate / hole injection layer (HIL) / hole transport layer (HTL1) / optional second hole transport layer (HTL2) / electron blocking layer (EBL) / emission layer (EML) / optional hole blocking layer (HBL) / electron transport layer (ETL1) / optional second electron transport layer (ETL2) / electron injection layer (EIL) and finally a cathode. The cathode is formed by a 100 nm thick aluminum layer. The exact structure of the OLEDs can be found in the following tables. The materials required to manufacture the OLEDs are shown in the following table. All materials are thermally vapor deposited in a vacuum chamber.The emission layer consists of at least one matrix material (host material) and an emitting dopant (emitter), which is mixed into the matrix material(s) by co-evaporation in a specific volume fraction. A specification such as H:SEB (95%:5%) means that the H material is present in a volume fraction of 95% and SEB in a volume fraction of 5% in the layer. Similarly, the electron-transport layer and the hole-injection layer also consist of a mixture of two materials. The structures of the materials used in the OLEDs are shown in the table below. ETM-2, used as the electron-transport material in OLED Example 11, is a spirobifluorenyl triazine derivative. EBM-2, used as the electron-blocking layer material in OLED Example 11, is a triarylamino-substituted spirobifluorene. The OLEDs are characterized according to standard procedures.For this purpose, the electroluminescence spectra, the external quantum efficiency (EQE, measured in %) as a function of luminance, calculated from current-voltage-luminance curves assuming a Lambertian radiation pattern, and the lifetime are determined. The specification EQE @ 10 mA / cm² refers to the external quantum efficiency achieved at 10 mA / cm². The lifetime LT is defined as the time after which the luminance drops from the starting luminance to a certain percentage when operated at a constant current density. A specification LT90 means that the specified lifetime corresponds to the time after which the luminance has dropped to 90% of its initial value. The specification @60 mA / cm. 2 means that the lifetime in question is 60 mA / cm 2 is measured. 2) Use in the electron-blocking layer of a blue fluorescent OLED: OLEDs with the following structure are manufactured: OLEDs 1-3 demonstrate that the compounds of the invention are excellent materials for OLEDs. The OLEDs exhibit excellent properties as hole-transport materials in this configuration, achieving very high external quantum efficiencies, low operating voltage, and very good lifetimes: 3) Use in the hole transport and electron blocking layer of a green phosphorescent OLED: OLEDs with the following structure are manufactured: OLEDs 4-7 demonstrate that the compounds of the invention are excellently suited as electron-blocking layer materials for green phosphorescent OLEDs. The OLEDs exhibit excellent properties as hole-transport and electron-blocking materials, achieving low operating voltages with good external quantum efficiencies and outstanding lifetimes: 3) Use in the hole transport layer of blue fluorescent OLEDs OLEDs with the following structure are manufactured: OLEDs 8-10 demonstrate that the compounds of the invention are excellently suited as hole-transport materials for blue-fluorescent OLEDs. The OLEDs exhibit very good properties as hole-transport materials, achieving low operating voltages with good external quantum efficiencies and outstanding lifetimes: Furthermore, the following blue fluorescent OLED is produced: OLED 11 demonstrates that the compounds of the invention are excellently suited as hole-transport materials for blue-fluorescent OLEDs. The OLED exhibits excellent hole-transport properties and achieves a low operating voltage with good external quantum efficiency and outstanding lifetime:

Claims

Claims 1. Electronic device comprising an anode, a cathode, an emitting layer, and a layer containing a compound of formula (I) arranged between the anode and the emitting layer, Formula (I), where the following applies to the variables occurring: G is a group according to formula (G), which is bonded to the rest of formula (I) via one of the free positions on the benzene rings, where the other free positions on the benzene rings are each bonded to a radical R 1 X 1 is O or S; X 2 is C(R 2 )2or Si(R 2 )2; X 3 is C(R 2 )2or Si(R 2 )2; Ar L is an aromatic ring system with 6 to 40 aromatic ring atoms, which is linked to residues R 3 substituted, or a heteroaromatic ring system with 5 to 40 aromatic ring atoms, which is substituted with residues R 3 is substituted; Ar 1 , Ar2 is, identically or differently, an aromatic ring system with 6 to 40 aromatic ring atoms, which is substituted with radicals R 4 substituted, or a heteroaromatic ring system with 5 to 25 aromatic ring atoms, which is substituted with radicals R 4 is substituted, where Ar 1 and Ar 2 can optionally be linked to each other via a bond or a group E; E is C(R 4 )2, -C(R 4 )2-C(R 4 )2-, -C(R 4 )=C(R 4 )-, C=O, Si(R 4 )2, NR 4 , O, S, S=O, or SO2; R 1 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5, straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 1 may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 2is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5 , straight-chain alkyl or alkoxy groups with 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups with 3 to 20 C atoms, alkenyl or alkynyl groups with 2 to 20 C atoms, aromatic ring systems with 6 to 40 aromatic ring atoms, and hetero- aromatic ring systems with 5 to 40 aromatic ring atoms; where two or more radicals R 2 may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 3 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5 , straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where two or more radicals R 3may be linked to one another and form a ring; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 4 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 5 , CN, Si(R 5 )3, N(R 5 )2, P(=O)(R 5 )2, OR 5 , S(=O)R 5 , S(=O)2R 5, straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each substituted by radicals R 5 are substituted; and wherein one or several CH2 groups in the above-mentioned alkyl, alkoxy, alkenyl and alkynyl groups are replaced by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; R 5 is selected at each occurrence, the same or different, from H, D, F, Cl, Br, I, C(=O)R 6 , CN, Si(R 6 )3, N(R6 )2, P(=O)(R 6 )2, OR 6 , S(=O)R 6 , S(=O)2R 6 , straight-chain alkyl or alkoxy groups having 1 to 20 C atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherein the said alkyl, alkoxy, alkenyl and alkynyl groups and the said aromatic ring systems and heteroaromatic ring systems are each substituted by radicals R 6 are substituted; and wherein one or more CH2 groups in said alkyl, alkoxy, alkenyl and alkynyl groups are substituted by -R 6 C=CR 6 -, -C≡C-, Si(R 6 )2, C=O, C=NR 6 , -C(=O)O-, -C(=O)NR 6 -, NR 6 , P(=O)(R 6 ), -O-, -S-, SO or SO2; R 6is selected, identically or differently at each occurrence, from H, D, F, Cl, Br, I, CN, alkyl or alkoxy groups having 1 to 20 C atoms, alkenyl or alkynyl groups having 2 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; and wherein the said alkyl, alkoxy, alkenyl and alkynyl groups, aromatic ring systems and heteroaromatic ring systems may be substituted by one or more radicals selected from F and CN; n is 0 or 1, where for n=0 the group G and the nitrogen atom in formula (I) are directly bonded to one another.

2. Electronic device according to claim 1, characterized in that formula (I) corresponds to one of the formulas (I-1-1), (I-1-2), (I-1-3), (I-1-4), (I-3-1), (I-3-2) wherein the variables occurring are defined as in claim 1, and wherein the further free positions on the benzene rings are each assigned a radical R 1 which in this case is preferably H.

3. Electronic device according to claim 1, characterized in that formula (I) corresponds to one of the formulas (I-4-1), (I-4-2) and (I-4-4), in particular formula (I-4-1) wherein the variables occurring are defined as in claim 1, and wherein the further free positions on the benzene rings are each assigned a radical R 1 which in this case is preferably H.

4. Electronic device according to claim 1, characterized in that formula (I) corresponds to formula (I-4-3), wherein the variables occurring are defined as in claim 1, and wherein the further free positions on the benzene rings are each assigned a radical R1 which in this case is preferably H, and wherein at least one of the conditions a) and b) is present: a) R 2 is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5 ), -O-, -S-, SO or SO2; b) index n is equal to 1.

5. Electronic device according to one of claims 1 to 4, characterized in that Ar Lis selected from phenyl, biphenyl, naphthyl and fluorenyl, each of which is substituted with residues R 3 are substituted; and is preferably selected from phenyl, which is substituted with radicals R 3 6. Electronic device according to one or more of claims 1 to 5, characterized in that at least one of the groups Ar 1 and Ar 2 is an aromatic ring system with at least 12 aromatic ring atoms, which is substituted by radicals R 4 is substituted.

7. Electronic device according to one or more of claims 1 to 6, characterized in that R 2is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms.

8. Electronic device according to one or more of claims 1 to 7, characterized in that the following definitions of the variables are present in combination with one another: G is a group according to formula (G) which is bonded to the radical of formula (I) via one of the free positions on the benzene rings, where the further free positions on the benzene rings are each linked to a radical R 1 are substituted; X 1 is O or S; X 2 is C(R 2 )2; X 3 is C(R 2 )2; Ar L is selected from phenyl, biphenyl, naphthyl and fluorenyl, each of which is substituted with radicals R 3 are substituted; Ar 1 , Ar 2 is, identically or differently, an aromatic ring system with 6 to 40 aromatic ring atoms, which is substituted with radicals R 4substituted, or a heteroaromatic ring system with 5 to 25 aromatic ring atoms, which is substituted with radicals R 4 is substituted; R 1 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic Ring systems and the above-mentioned heteroaromatic ring systems each with residues R 5 are substituted; R 2 is selected, identically or differently at each occurrence, from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; R 3is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; R 4 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 5 are substituted; R5 is selected, identically or differently at each occurrence, from H, D, straight-chain alkyl groups having 1 to 20 C atoms, branched or cyclic alkyl groups having 3 to 20 C atoms, aromatic ring systems having 6 to 40 aromatic ring atoms, and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the said alkyl groups, the said aromatic ring systems and the said heteroaromatic ring systems are each substituted by radicals R 6 are substituted, and where radicals R 6 are equal to H; n is equal to 0 or 1.

9. Electronic device according to one or more of claims 1 to 8, characterized in that in the compound of formula (I) the group G is selected from one of the following formulas: wherein the group G is bonded to the radical of formula (I) via one of the free positions on the benzene rings, wherein the further free positions on the benzene rings are each bonded to a radical R 1 are substituted, and wherein, among formulas (G-1) to (G-6), formulas (G-1) and (G-2) are preferred, and formula (G-1) is particularly preferred.

10. The electronic device according to one or more of claims 1 to 9, characterized in that the layer containing a compound of formula (I) is selected from a hole-injection layer, a hole-transport layer, and an electron-blocking layer.

11. A compound according to a formula (I) Formula (I), where the variables G, X 1 , X 2 , X 3 , Ar L , Ar 1 , Ar 2 , E, R 1 , R 3 , R 4 , R 5 , R 6and n are defined as in one or more of claims 1, 5, 6, 7, 8 and 9, and furthermore: R 2 is the same or different and is selected from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; where two or more radicals R 2 can be linked together to form a ring; wherein the alkyl groups mentioned are each linked to radicals R 5 are substituted; and wherein one or more CH2 groups in said alkyl groups are substituted by -R 5 C=CR 5 -, -C≡C-, Si(R 5 )2, C=O, C=NR 5 , -C(=O)O-, -C(=O)NR 5 -, NR 5 , P(=O)(R 5), -O-, -S-, SO or SO2; preferably identically or differently selected from straight-chain alkyl groups having 1 to 20 C atoms and branched or cyclic alkyl groups having 3 to 20 C atoms; particularly preferably methyl. 12.A process for preparing a compound according to claim 11, characterized in that at least one sequence of process steps a) followed by b) is present, wherein process step a) comprises a reaction in which a carboxylic acid ester group bonding to a biphenyl unit in the ortho position to the bond between the two benzene rings of the biphenyl unit is converted into a tertiary alcohol group by addition of a metal organyl, preferably a Grignard reagent, and wherein process step b) comprises a reaction in which the tertiary alcohol group obtained in process step a) undergoes a ring closure reaction under acidic conditions, in particular acidic ion exchange resin, such as Amberlyst-15, so that a fluorenyl unit is formed from the biphenyl unit.Oligomers, polymers or dendrimers containing one or more compounds according to claim 11, wherein the bond(s) to the polymer, oligomer or dendrimer are at any desired bond(s) identified in formula (I) with R. 1 , R 2 , R 3 , or R 4 substituted positions.

14. A formulation comprising at least one compound according to claim 11 or at least one polymer, oligomer, or dendrimer according to claim 13, and at least one solvent.

15. An electronic device, in particular an organic electroluminescent device, comprising at least one compound according to claim 11 or at least one polymer, oligomer, or dendrimer according to claim 13.

16. Use of a compound according to claim 11 in an electronic device, in particular an organic electroluminescent device.

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