Patent Application
20230413662
The present application relates to spirobifluoreneamines having, as well the amino group, at least one further substituent on the spirobifluorene base skeleton. The compounds are suitable for use in electronic devices.
Electronic devices in the context of this application are understood to mean what are called organic electronic devices, which comprise organic semiconductor materials as functional materials. More particularly, these are understood to mean OLEDs (organic electroluminescent devices). The term OLEDs is understood to mean electronic devices which have one or more layers comprising organic compounds and emit light on application of electrical voltage. The construction and general principle of function of OLEDs are known to those skilled in the art.
In electronic devices, especially OLEDs, there is great interest in an improvement in the performance data. In these aspects, it has not yet been possible to find any entirely satisfactory solution.
A great influence on the performance data of electronic devices is possessed by emission layers and layers having a hole-transporting function. Novel compounds are also being sought for use in these layers, especially hole-transporting compounds and compounds that can serve as hole-transporting matrix material, especially for phosphorescent emitters, in an emitting layer. For this purpose, there is a search especially for compounds that have a high glass transition temperature, high stability, and high conductivity for holes. A high stability of the compound is a prerequisite for achieving a long lifetime of the electronic device. There is moreover a need to find compounds whose use in electronic devices results in improvement of the performance data of the devices, especially in high efficiency, long lifetime and low operating voltage.
In the prior art, triarylamine compounds such as spirobifluoreneamines and fluoreneamines in particular are known as hole transport materials and hole-transporting matrix materials for electronic devices. However, there remains room for improvement in respect of the abovementioned properties.
It has now been found that spirobifluoreneamines of formula (I) or (II) below that are characterized in that they have, as well as the amino group, at least one further substituent on the spirobifluorene base skeleton are of excellent suitability for use in electronic devices. They are especially suitable for use in OLEDs, and even more particularly therein for use as hole transport materials and for use as hole-transporting matrix materials, especially for phosphorescent emitters. The compounds lead to high lifetime, high efficiency and low operating voltage of the devices. Further preferably, the compounds found have a high glass transition temperature, high stability and high conductivity for holes.
The present application thus provides a compound of a formula (I) or (II)
When a, b, c, d, e, f, g, and h are greater than 1, this means that two or more R1 groups that are the same or different are bonded to the corresponding ring, and each is bonded to a different position on the ring.
The definitions which follow are applicable to the chemical groups that are used in the present application. They are applicable unless any more specific definitions are given.
An aryl group in the context of this invention is understood to mean either a single aromatic cycle, i.e. benzene, or a fused aromatic polycycle, for example naphthalene, phenanthrene or anthracene. A fused aromatic polycycle in the context of the present application consists of two or more single aromatic cycles fused to one another. Fusion between cycles is understood here to mean that the cycles share at least one edge with one another. An aryl group in the context of this invention contains 6 to 40 aromatic ring atoms. In addition, an aryl group does not contain any heteroatom as aromatic ring atom, but only carbon atoms.
A heteroaryl group in the context of this invention is understood to mean either a single heteroaromatic cycle, for example pyridine, pyrimidine or thiophene, or a fused heteroaromatic polycycle, for example quinoline or carbazole. A fused heteroaromatic polycycle in the context of the present application consists of two or more single aromatic or heteroaromatic cycles that are fused to one another, where at least one of the aromatic and heteroaromatic cycles is a heteroaromatic cycle. Fusion between cycles is understood here to mean that the cycles share at least one edge with one another. A heteroaryl group in the context 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, each of which may be substituted by the abovementioned radicals, is especially understood to mean groups derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, triphenylene, fluoranthene, benzanthracene, benzophenanthrene, tetracene, pentacene, benzopyrene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, 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 in the context of this invention is a system which does not necessarily contain solely aryl groups, but which may additionally contain one or more nonaromatic rings fused to at least one aryl group. These nonaromatic rings contain exclusively carbon atoms as ring atoms. Examples of groups covered by this definition are tetrahydronaphthalene, fluorene and spirobifluorene. In addition, the term “aromatic ring system” includes systems that consist of two or more aromatic ring systems joined 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 in the context of this invention contains 6 to 40 carbon atoms and no heteroatoms in the ring system. The definition of “aromatic ring system” does not include heteroaryl groups.
A heteroaromatic ring system conforms to the abovementioned definition of an aromatic ring system, except that it must contain at least one heteroatom as ring atom. As is the case for the aromatic ring system, the heteroaromatic ring system need not contain exclusively aryl groups and heteroaryl groups, but may additionally contain one or more nonaromatic rings fused to at least one aryl or heteroaryl group. The nonaromatic rings may contain exclusively carbon atoms as ring atoms, or they may additionally contain one or more heteroatoms, where the heteroatoms are preferably selected from N, O and S. One example of such a heteroaromatic ring system is benzopyranyl. In addition, the term “heteroaromatic ring system” is understood to mean systems that consist of two or more aromatic or heteroaromatic ring systems that are bonded to one another via single bonds, for example 4,6-diphenyl-2-triazinyl. A heteroaromatic ring system in the context of this invention contains 5 to 40 ring atoms selected from carbon and heteroatoms, where 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 ring atom, whereas a heteroaromatic ring system must have at least one heteroatom as ring atom. This heteroatom may be present as a ring atom of a nonaromatic heterocyclic ring or as a ring atom of an aromatic heterocyclic ring.
In accordance with the above definitions, any aryl group is covered by the term “aromatic ring system”, and any heteroaryl group is covered by the term “heteroaromatic ring system”.
An aromatic ring system having 6 to 40 aromatic ring atoms or a heteroaromatic ring system having 5 to 40 aromatic ring atoms is especially understood to mean groups derived from the groups mentioned above under aryl groups and heteroaryl groups, and from biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, indenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, indenocarbazole, or from combinations of these groups.
In the context of the present invention, a straight-chain alkyl group having 1 to 20 carbon atoms and a branched or cyclic alkyl group having 3 to 20 carbon atoms and an alkenyl or alkynyl group having 2 to 40 carbon atoms in which individual hydrogen atoms or CH2 groups may also be substituted by the groups mentioned above in the definition of the radicals are preferably understood to mean the methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, neohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl, trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl or octynyl radicals.
An alkoxy or thioalkyl group having 1 to 20 carbon atoms in which individual hydrogen atoms or CH2 groups may also be substituted by the groups mentioned above in the definition of the radicals is preferably understood to mean methoxy, trifluoromethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, s-pentoxy, 2-methylbutoxy, n-hexoxy, cyclohexyloxy, n-heptoxy, cycloheptyloxy, n-octyloxy, cyclooctyloxy, 2-ethylhexyloxy, pentafluoroethoxy, 2,2,2-trifluoroethoxy, methylthio, ethylthio, n-propylthio, i-propylthio, n-butylthio, i-butylthio, s-butylthio, t-butylthio, n-pentylthio, s-pentylthio, n-hexylthio, cyclohexylthio, n-heptylthio, cycloheptylthio, n-octylthio, cyclooctylthio, 2-ethylhexylthio, trifluoromethylthio, pentafluoroethylthio, 2,2,2-trifluoroethylthio, ethenylthio, propenylthio, butenylthio, pentenylthio, cyclopentenylthio, hexenylthio, cyclohexenylthio, heptenylthio, cycloheptenylthio, octenylthio, cyclooctenylthio, ethynylthio, propynylthio, butynylthio, pentynylthio, hexynylthio, heptynylthio or octynylthio.
The wording that two or more radicals together may form a ring, in the context of the present application, shall be understood to mean, inter alia, that the two radicals are joined to one another by a chemical bond. In addition, however, the abovementioned wording shall also be understood to mean that, if one of the two radicals is hydrogen, the second radical binds to the position to which the hydrogen atom was bonded, forming a ring.
The compound according to the application preferably conforms to the formula (I).
Preferred Ar1 groups are the same or different at each instance and are selected from monovalent groups derived from benzene, biphenyl, terphenyl, quaterphenyl, naphthalene, fluorene, especially 9,9′-dimethylfluorene and 9,9′-diphenylfluorene, benzofluorene, spirobifluorene, indenofluorene, indenocarbazole, dibenzofuran, dibenzothiophene, benzocarbazole, carbazole, benzofuran, benzothiophene, indole, quinoline, pyridine, pyrimidine, pyrazine, pyridazine and triazine, where each of the monovalent groups is substituted by R2 radicals. Preference is given to Ar1 groups that are the same or different at each instance and are selected from combinations of 2 to 4 groups derived from benzene, biphenyl, terphenyl, quaterphenyl, naphthalene, fluorene, especially 9,9′-dimethylfluorene and 9,9′-diphenylfluorene, benzofluorene, spirobifluorene, indenofluorene, indenocarbazole, dibenzofuran, dibenzothiophene, benzocarbazole, carbazole, benzofuran, benzothiophene, indole, quinoline, pyridine, pyrimidine, pyrazine, pyridazine and triazine, where each of the monovalent groups is substituted by R2 radicals.
Particularly preferred Ar1 groups are the same or different at each instance and selected from benzene, biphenyl, terphenyl, quaterphenyl, naphthyl, fluorenyl, especially 9,9′-dimethylfluorenyl and 9,9′-diphenylfluorenyl, benzofluorenyl, spirobifluorenyl, indenofluorenyl, indenocarbazolyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzofuranyl, benzothiophenyl, benzofused dibenzofuranyl, benzofused dibenzothiophenyl, and phenyl substituted by a group selected from naphthyl, fluorenyl, spirobifluorenyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, pyridyl, pyrimidyl and triazinyl, where the groups are each substituted by R2 radicals.
Ar1 is preferably the same or different at each instance and is selected from groups of the following formulae:
Among these groups, particular preference is given to Ar1-1, Ar1-2, Ar1-3, Ar1-4, Ar1-5, Ar1-50, Ar1-56, Ar1-66, Ar1-78, Ar1-82, Ar1-108, Ar1-111, Ar1-114, Ar1-140, Ar1-141, Ar1-142, Ar1-149, Ar1-154, Ar1-257, Ar1-262 and Ar1-263.
In a preferred embodiment, m=0.
In an alternative preferred embodiment, m=1, such that the two Ar1 groups bonded to a nitrogen atom are bonded to an E group.
The E group is preferably selected from single bond, —C(R0)2, —NR0—, O, and S.
ArL is preferably the same or different at each instance and is selected from aromatic or heteroaromatic rings having 6 aromatic ring atoms and aromatic or heteroaromatic ring systems having 10 to 14 aromatic ring atoms, more preferably selected from phenyl, biphenyl, naphthyl, phenanthrenyl, fluorenyl, carbazolyl, dibenzofuranyl and dibenzothiophenyl, each of which are substituted by R3 radicals; most preferably selected from phenyl substituted by R3 radicals.
Preferably, ArL is the same or different at each instance and is selected from groups of the following formulae:
In a preferred embodiment, n=0, such that the amino group and the spirobifluorene are bonded directly to one another.
In an alternative, likewise preferred embodiment, n=1, such that an ArL group is present between the amino group and the spirobifluorene.
R0 is preferably the same or different at each instance, preferably the same, and is selected from H, D, F, CN, Si(R4)3, N(R4)2, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl and alkoxy groups mentioned, the aromatic ring systems mentioned and the heteroaromatic ring systems mentioned are each substituted by R4 radicals; and where one or more CH2 groups in the alkyl or alkoxy groups mentioned may be replaced by —C≡C—, —R4C═CR4—, Si(R4)2, C═O, C═NR4, —NR4—, —O—, —S—, —C(═O)O— or —C(═O)NR4—. When R0 is part of a group E=—C(R0)2—, —C(R0)2—C(R0)2—, —CR0═CR0—, or —NR0—, R0 is preferably not H or D.
R1 is preferably the same at each instance.
R1 is preferably the same or different at each instance and is selected from CN, Si(R4)3, straight-chain alkyl groups having 1 to 20 carbon atoms, branched or cyclic alkyl groups having 3 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl groups mentioned and the aromatic ring systems and heteroaromatic ring systems mentioned are each substituted by R4 radicals, where R4 in these cases is preferably H. More preferably, R1 is the same or different at each instance and is selected from straight-chain alkyl groups having 1 to 20 carbon atoms; branched or cyclic alkyl groups having 3 to 20 carbon atoms; aromatic ring systems, preferably aryl groups, having 6 to 40 aromatic ring atoms; and heteroaromatic ring systems, preferably heteroaryl groups, having 5 to 40 aromatic ring atoms; where the alkyl groups mentioned, the aromatic ring systems mentioned, the heteroaromatic ring systems mentioned, the aryl groups mentioned and the heteroaryl groups mentioned are each substituted by R4 radicals, where R4 in these cases is preferably H. Even more preferably, R1 is the same or different at each instance and is selected from methyl, —CD3, tert-butyl, —C(CD3)3, phenyl, naphthyl, and carbazolyl. Most preferably, R1 is methyl or tert-butyl.
For all the abovementioned preferred embodiments of R1, it is preferable that, in combination with this embodiment, in the compound, an H is bonded to all positions in the six-membered ring of the spirobifluorene, where no R1 is bonded.
It is generally preferable that the compounds bear an H in all positions in the six-membered ring of the spirobifluorene where no R1 radical is bonded.
The preferences applicable to Ar2 are the same as specified above for Ar1.
Preferably, R2 is the same or different at each instance and is selected from H, D, F, CN, Si(R4)3, N(R4)2, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl and alkoxy groups mentioned, the aromatic ring systems mentioned and the heteroaromatic ring systems mentioned are each substituted by R4 radicals; and where one or more CH2 groups in the alkyl or alkoxy groups mentioned may be replaced by —C═C—, —R4C═CR4—, Si(R4)2, C═O, C═NR4, —NR4—, —O—, —S—, —C(═O)O— or —C(═O)NR4—.
Preferably, R3 is the same or different at each instance and is selected from H, D, F, CN, Si(R4)3, N(R4)2, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl and alkoxy groups mentioned, the aromatic ring systems mentioned and the heteroaromatic ring systems mentioned are each substituted by R4 radicals; and where one or more CH2 groups in the alkyl or alkoxy groups mentioned may be replaced by —C═C—, —R4C═CR4—, Si(R4)2, C═O, C═NR4, —NR4—, —O—, —S—, —C(═O)O— or —C(═O)NR4—.
Preferably, R4 is the same or different at each instance and is selected from H, D, F, CN, Si(R5)3, N(R5)2, straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms, aromatic ring systems having 6 to 40 aromatic ring atoms and heteroaromatic ring systems having 5 to 40 aromatic ring atoms; where the alkyl and alkoxy groups mentioned, the aromatic ring systems mentioned and the heteroaromatic ring systems mentioned are each substituted by R5 radicals; and where one or more CH2 groups in the alkyl or alkoxy groups mentioned may be replaced by —C≡C—, —R5C═CR5—, Si(R5)2, C═O, C═NR5, —NR5—, —O—, —S—, —C(═O)O— or —C(═O)NR5—.
Preferably, the abovementioned preferred embodiments of R2, R3 and R4 occur in combination.
In a preferred embodiment, a is 1 or 2, more preferably 1.
In a preferred embodiment, b is 0, 1 or 2, more preferably 1 or 2.
In a preferred embodiment, a is 1 or 2, and b is 1 or 2.
In a preferred embodiment, c is 0.
In a preferred embodiment, d is 0.
In a preferred embodiment, c and d are both 0.
Preferably, e is 0.
Preferably, f is 1 or 2, more preferably 2.
Preferably, g is 0 or 1, more preferably 0.
Preferably, h is 0 or 1, more preferably 0.
Preferably, g is 0 and h is 0.
In a preferred embodiment, formula (I) conforms to the following formula:
In a particularly preferred embodiment, formula (1-1) conforms to one of the following formulae:
Preferably, in formula (I-1-1), a′, b′, c and d are 0.
Preferably, in formula (I-1-2), a″, b″, c and d are 0.
Further preferred formulae are the following formulae:
In a preferred embodiment, formula (II) conforms to one of the following formulae:
Further preferred formulae are the following formulae:
In a further preferred embodiment, in formula (I) and (II), there is an R1 group that is N(Ar2)2 in each case. Preferred embodiments of the compounds conform to the following formulae in this case:
More preferably, a is at least 1 and b″′ is at least 1.
It is further preferable that e is at least 1. It is further preferable that f′ is at least 1. More preferably, e is at least 1 and f′ is at least 1.
In a preferred embodiment, the unit
Preferred compounds conform to the following formulae:
Preference is further given to a compound of formula (I), especially formula (I-1-1), for which the following definitions are applicable:
The following compounds are preferred as well as the compounds from the synthesis examples and device examples:
The compounds of formula (I) and (II) can be prepared as follows:
The synthesis of compounds of the formula (I) proceeds from biphenyl derivatives having halogen groups in the two ortho positions to the bond between the phenyl groups. These can be prepared by Suzuki reaction. The biphenyl derivatives are additionally substituted by at least one organic radical, preferably at least one radical selected from aromatic or heteroaromatic ring systems and alkyl groups. In a subsequent step, in an addition reaction and subsequent cyclization reaction, they are reacted with a fluorenone derivative to give a spirobifluorene having a halogen atom in the 4 position (Scheme 1).
R in the abovementioned scheme is any organic radical, preferably H, aromatic or heteroaromatic ring system or alkyl, and X is a halogen atom, preferably Cl, Br or I.
In a subsequent step, the intermediates obtained in Scheme 1) can be reacted a) with a secondary amine in a Buchwald coupling, or b) with a triarylamine in a Suzuki coupling, or c) in a two-step process, firstly with an aromatic or heteroaromatic in a Suzuki coupling and then with a secondary amine in a Buchwald coupling (Scheme 2):
R in the abovementioned scheme is any organic radical, preferably H, aromatic ring system, heteroaromatic ring system or alkyl, and X is a halogen atom, preferably Cl, Br or I, and ArL is aromatic ring system or heteroaromatic ring system, and G1 and G2 are selected from aromatic or heteroaromatic ring systems.
The synthesis of compounds of the formula (II) proceeds from biphenyl derivatives having, on one of the two six-membered rings, halogen groups both in the ortho position and in the para position to the bond between the six-membered rings. These can be prepared by Suzuki reaction. The biphenyl derivatives are additionally substituted by at least one organic radical, preferably at least one radical selected from aromatic or heteroaromatic ring systems and alkyl groups. In a subsequent step, in an addition reaction and subsequent cyclization reaction, they are reacted with a fluorenone derivative to give a spirobifluorene having a halogen atom in the 2 position (Scheme 3).
R in the abovementioned scheme is any organic radical, preferably H, aromatic or heteroaromatic ring system or alkyl, and X is a halogen atom, preferably Cl, Br or I.
In a subsequent step, the intermediates obtained in Scheme 3) can be reacted a) with a secondary amine in a Buchwald coupling, or b) with a triarylamine in a Suzuki coupling, or c) in a two-step process, firstly with an aromatic or heteroaromatic in a Suzuki coupling and then with a secondary amine in a Buchwald coupling (Scheme 4):
R in scheme 4 is any organic radical, preferably H, aromatic ring system, heteroaromatic ring system or alkyl, and X is a halogen atom, preferably Cl, Br or I, and ArL is aromatic ring system or heteroaromatic ring system, and G1 and G2 are selected from aromatic or heteroaromatic ring systems.
The present application thus provides a process for preparing a compound of formula (I) or (II), characterized in that a biphenyl derivative substituted by two halogen atoms and substituted by at least one organic radical preferably selected from aromatic or heteroaromatic ring systems and alkyl groups is reacted with a fluorenone derivative.
The reaction here is preferably an addition reaction followed by a cyclization reaction, forming a spirobifluorene derivative, which is converted further to a compound of the formula (I) or (II).
The above-described compounds of the invention, especially compounds substituted by reactive leaving groups, such as bromine, iodine, chlorine, boronic acid or boronic ester, may find use as monomers for production of corresponding oligomers, dendrimers or polymers. Suitable reactive leaving groups are, for example, bromine, iodine, chlorine, boronic acids, boronic esters, amines, alkenyl or alkynyl groups having a terminal C═C double bond or C—C triple bond, oxiranes, oxetanes, groups which enter into a cycloaddition, for example a 1,3-dipolar cycloaddition, for example dienes or azides, carboxylic acid derivatives, alcohols and silanes.
The invention therefore further provides oligomers, polymers or dendrimers containing one or more compounds of formula (I) or (II), wherein the bond(s) to the polymer, oligomer or dendrimer may be localized at any desired positions substituted by R0, R1, R2 or R3 in formula (I) or (II). According to the linkage of the compound of formula (I) or (II), the compound is part of a side chain of the oligomer or polymer or part of the main chain. An oligomer in the context of this invention is understood to mean a compound formed from at least three monomer units. A polymer in the context of the invention is understood to mean a compound formed from at least ten monomer units. The polymers, oligomers or dendrimers of the invention may be conjugated, partly conjugated or nonconjugated. The oligomers or polymers of the invention may be linear, branched or dendritic. In the structures having linear linkage, the units of formula (I) or (II) may be joined directly to one another, or they may be joined to one another via a bivalent group, for example via a substituted or unsubstituted alkylene group, via a heteroatom or via a bivalent aromatic or heteroaromatic group. In branched and dendritic structures, it is possible, for example, for three or more units of formula (I) or (II) to be joined via a trivalent or higher-valency group, for example via a trivalent or higher-valency aromatic or heteroaromatic group, to give a branched or dendritic oligomer or polymer.
For the repeat units of formula (I) or (II) in oligomers, dendrimers and polymers, the same preferences apply as described above for compounds of formula (I) or (II).
For preparation of the oligomers or polymers, the monomers of the invention are homopolymerized or copolymerized with further monomers. Suitable and preferred comonomers are selected from fluorenes, spirobifluorenes, paraphenylenes, carbazoles, thiophenes, dihydrophenanthrenes, cis- and trans-indenofluorenes, ketones, phenanthrenes or else two or more of these units. The polymers, oligomers and dendrimers typically contain still further units, for example emitting (fluorescent or phosphorescent) units, for example vinyltriarylamines or phosphorescent metal complexes, and/or charge transport units, especially those based on triarylamines.
The polymers, oligomers and dendrimers of the invention have advantageous properties, especially high lifetimes, high efficiencies and good colour coordinates.
The polymers and oligomers of the invention are generally prepared by polymerization of one or more monomer types, of which at least one monomer leads to repeat units of the formula (I) or (II) in the polymer. Suitable polymerization reactions are known to those skilled in the art and are described in the literature. Particularly suitable and preferred polymerization reactions which lead to C—C and C—N couplings are as follows:
How the polymerization can be conducted by these methods and how the polymers can then be separated from the reaction medium and purified is known to those skilled in the art and is described in detail in the literature.
For the processing of the compounds of the invention from a liquid phase, for example by spin-coating or by printing methods, formulations of the compounds of the invention are required. These formulations may, for example, be solutions, dispersions or emulsions. For this purpose, it may be preferable to use mixtures of two or more solvents. 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, especially 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, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethylene glycol butyl methyl ether, triethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane, or mixtures of these solvents.
The invention therefore further provides a formulation, especially a solution, dispersion or emulsion, comprising at least one compound of formula (I) or (II) or at least one polymer, oligomer or dendrimer containing at least one unit of formula (I) or (II) and at least one solvent, preferably an organic solvent. The way in which such solutions can be prepared is known to those skilled in the art.
The compound of formula (I) or (II) is suitable for use in an electronic device, especially an organic electroluminescent device (OLED).
Depending on the substitution, the compound of the formula (I) or (II) 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 matrix material in an emitting layer, more preferably in combination with a phosphorescent emitter.
The invention therefore further provides for the use of a compound of formula (I) or (II) in an electronic device. This 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 more preferably organic electroluminescent devices (OLEDs).
The invention further provides an electronic device comprising at least one compound of formula (I) or (II). This electronic device is preferably selected from the abovementioned devices.
Particular preference is given to an organic electroluminescent device comprising anode, cathode and at least one emitting layer, characterized in that at least one organic layer comprising at least one compound of formula (I) or (II) is present in the device. Preference is given to an organic electroluminescent device comprising anode, 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, comprises at least one compound of formula (I) or (II).
A hole-transporting layer is understood here to mean all layers disposed between anode and emitting layer, preferably hole injection layer, hole transport layer and electron blocker layer. A hole injection layer is understood here to mean a layer that directly adjoins the anode. A hole transport layer is understood here to mean a layer which is between the anode and emitting layer but does not directly adjoin the anode, and preferably does not directly adjoin the emitting layer either. An electron blocker layer is understood here to mean a layer which is between the anode and emitting layer and directly adjoins the emitting layer. An electron blocker layer preferably has a high-energy LUMO and hence prevents electrons from exiting from the emitting layer.
Apart from the cathode, anode and emitting layer, the electronic device may comprise further layers. These are selected, for example, from in each case one or more hole injection layers, hole transport layers, hole blocker layers, electron transport layers, electron injection layers, electron blocker layers, exciton blocker layers, interlayers, charge generation layers and/or organic or inorganic p/n junctions. However, it should be pointed out that not every one of these layers need necessarily be present and the choice of layers always depends on the compounds used and especially also on whether the device is a fluorescent or phosphorescent electroluminescent device.
The sequence of layers in the electronic device is preferably as follows:
At the same time, it should be pointed out again that not all the layers mentioned need be present and/or that further layers may additionally be present.
The organic electroluminescent device of the invention may contain two or more emitting layers. More preferably, these emission layers have several emission maxima between 380 nm and 750 nm overall, such that the overall result is white emission; in other words, various emitting compounds which may fluoresce or phosphoresce and which emit blue, green, yellow, orange or red light are used in the emitting layers. Especially preferred are three-layer systems, i.e. systems having three emitting layers, wherein one of the three layers in each case shows blue emission, one of the three layers in each case shows green emission, and one of the three layers in each case shows orange or red emission. The compounds of the invention here are preferably present in a hole-transporting layer or in the emitting layer. It should be noted that, for the production of white light, rather than a plurality of colour-emitting emitter compounds, an emitter compound used individually which emits over a broad wavelength range may also be suitable.
It is preferable that the compound of the formula (I) or (II) is used as hole transport material. The emitting layer here may be a fluorescent emitting layer, or it may be a phosphorescent emitting layer. The emitting layer is preferably a blue-fluorescing layer or a green-phosphorescing layer.
When the device containing the compound of the formula (I) or (II) contains a phosphorescent emitting layer, it is preferable that this layer contains two or more, preferably exactly two, different matrix materials (mixed matrix system). Preferred embodiments of mixed matrix systems are described in detail further down.
If the compound of formula (I) or (II) is used as hole transport material in a hole transport layer, a hole injection layer or an electron blocker layer, the compound can be used as 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.
In a preferred embodiment, a hole-transporting layer comprising the compound of the formula (I) or (II) additionally comprises one or more further hole-transporting compounds. These further hole-transporting compounds are preferably selected from triarylamine compounds, more preferably from monotriarylamine compounds. They are most preferably selected from the preferred embodiments of hole transport materials that are specified further down. In the preferred embodiment described, the compound of the formula (I) or (II) and the one or more further hole-transporting compounds are preferably each present in a proportion of at least 10%, more preferably each in a proportion of at least 20%.
In a preferred embodiment, a hole-transporting layer comprising the compound of the formula (I) or (II) additionally contains one or more p-dopants. p-Dopants used according to the present invention are preferably those organic electron acceptor compounds capable of oxidizing one or more of the other compounds in the mixture.
Particularly preferred as p-dopants are quinodimethane compounds, azaindenofluorenediones, azaphenalenes, azatriphenylenes, 12, metal halides, preferably transition metal halides, metal oxides, preferably metal oxides comprising at least one transition metal or a metal from 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 binding site. Preference is further given to transition metal oxides as dopants, preferably oxides of rhenium, molybdenum and tungsten, more preferably Re2O7, MoO3, WOs and ReO3. Still further preference is given to complexes of bismuth in the (III) oxidation state, more particularly bismuth(III) complexes with electron-deficient ligands, more particularly carboxylate ligands.
The p-dopants are preferably in substantially homogeneous distribution 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.
Preferred p-dopants are especially the following compounds:
In a preferred embodiment, a hole injection layer that conforms to one of the following embodiments is present in the device: a) it contains a triarylamine and a p-dopant; or b) it contains a single electron-deficient material (electron acceptor). In a preferred embodiment of embodiment a), the triarylamine is a monotriarylamine, especially one of the preferred triarylamine derivatives mentioned further down. In a preferred embodiment of embodiment b), the electron-deficient material is a hexaazatriphenylene derivative as described in US 2007/0092755.
The compound of the formula (I) or (II) may be present in a hole injection layer, in a hole transport layer and/or in an electron blocker layer of the device. When the compound is present in a hole injection layer or in a hole transport layer, it has preferably been p-doped, meaning that it is in mixed form with a p-dopant, as described above, in the layer.
The compound of the formula (I) or (II) is preferably present in an electron blocker layer. In this case, it is preferably not p-doped. Further preferably, in this case, it is preferably in the form of a single compound in the layer without addition of a further compound.
In an alternative preferred embodiment, the compound of the formula (I) or (II) is used in an emitting layer as matrix material in combination with one or more emitting compounds, preferably phosphorescent emitting compounds.
The phosphorescent emitting compounds here are preferably selected from red-phosphorescing and green-phosphorescing compounds.
The proportion of the matrix material in the emitting layer in this case is between 50.0% and 99.9% by volume, preferably between 80.0% and 99.5% by volume, and more preferably between 85.0% and 97.0% by volume.
Correspondingly, the proportion of the emitting compound is between 0.1% and 50.0% by volume, preferably between 0.5% and 20.0% by volume, and more preferably between 3.0% and 15.0% by volume.
An emitting layer of an organic electroluminescent device may also contain systems comprising a plurality of matrix materials (mixed matrix systems) and/or a plurality of emitting compounds. In this case too, the emitting compounds are generally those compounds having the smaller proportion in the system and the matrix materials are those compounds having the greater proportion in the system. In individual cases, however, the proportion of a single matrix material in the system may be less than the proportion of a single emitting compound.
It is preferable that the compounds of formula (I) or (II) 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, more preferably two different matrix materials. Preferably, in this case, one of the two materials is a material having hole-transporting properties and the other material is a material having electron-transporting properties. It is further preferable when one of the materials is selected from compounds having a large energy differential between HOMO and LUMO (wide-bandgap materials). The compound of the formula (I) or (II) in a mixed matrix system is preferably the matrix material having hole-transporting properties. Correspondingly, when the compound of the formula (I) or (II) is used as matrix material for a phosphorescent emitter in the emitting layer of an OLED, a second matrix compound having electron-transporting properties is present in the emitting layer. The two different matrix materials may be present here in a ratio of 1:50 to 1:1, preferably 1:20 to 1:1, more preferably 1:10 to 1:1 and most preferably 1:4 to 1:1.
The desired electron-transporting and hole-transporting properties of the mixed matrix components may, however, also be combined mainly or entirely in a single mixed matrix component, in which case the further mixed matrix component(s) fulfil(s) other functions.
Preference is given to using the following material classes in the abovementioned layers of the device:
The term “phosphorescent emitters” typically encompasses compounds where the emission of light is effected through a spin-forbidden transition, for example a transition from an excited triplet state or a state having a higher spin quantum number, for example a quintet state.
Suitable phosphorescent emitters are especially compounds which, when suitably excited, emit light, preferably in the visible region, and also contain at least one atom of atomic number greater than 20, preferably greater than 38, and less than 84, more preferably greater than 56 and less than 80. Preference is given to using, as phosphorescent emitters, compounds containing copper, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold or europium, especially compounds containing iridium, platinum or copper.
In the context of the present invention, all luminescent iridium, platinum or copper complexes are considered to be phosphorescent compounds.
In general, all phosphorescent complexes as used for phosphorescent OLEDs according to the prior art and as known to those skilled in the art in the field of organic electroluminescent devices are suitable for use in the devices of the invention. Further examples of suitable phosphorescent emitters are shown in the following table:
Preferred fluorescent emitting compounds are selected from the class of the arylamines. An arylamine or an aromatic amine in the context of this invention is understood to mean a compound containing three substituted or unsubstituted aromatic or heteroaromatic ring systems bonded directly to the nitrogen. Preferably, at least one of these aromatic or heteroaromatic ring systems is a fused ring system, more preferably having at least 14 aromatic ring atoms. Preferred examples of these are aromatic anthraceneamines, aromatic anthracenediamines, aromatic pyreneamines, aromatic pyrenediamines, aromatic chryseneamines or aromatic chrysenediamines. An aromatic anthraceneamine is understood to mean 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 mean a compound in which two diarylamino groups are bonded directly to an anthracene group, preferably in the 9,10 position. Aromatic pyreneamines, pyrenediamines, chryseneamines and chrysenediamines are defined analogously, where the diarylamino groups are bonded to the pyrene preferably in the 1 position or 1,6 position. Further preferred emitting compounds are indenofluoreneamines or -diamines, benzoindenofluoreneamines or -diamines, and dibenzoindenofluoreneamines or -diamines, and indenofluorene derivatives having fused aryl groups. Likewise preferred are pyrenearylamines. Likewise preferred are benzoindenofluoreneamines, benzofluoreneamines, extended benzoindenofluorenes, phenoxazines, and fluorene derivatives joined to furan units or to thiophene units.
Preferred matrix materials for fluorescent emitters are selected from the classes of the oligoarylenes (e.g. 2,2′,7,7′-tetraphenylspirobifluorene), especially the oligoarylenes containing fused aromatic groups, the oligoarylenevinylenes, the polypodal metal complexes, the hole-conducting compounds, the electron-conducting compounds, especially ketones, phosphine oxides and sulfoxides; the atropisomers, the boronic acid derivatives or the benzanthracenes. Particularly preferred matrix materials are selected from the classes of the oligoarylenes comprising naphthalene, anthracene, benzanthracene and/or pyrene or atropisomers of these compounds, the oligoarylenevinylenes, the ketones, the phosphine oxides and the sulfoxides. Very particularly preferred matrix materials are selected from the classes of the oligoarylenes comprising anthracene, benzanthracene, benzophenanthrene and/or pyrene or atropisomers of these compounds. An oligoarylene in the context of this invention shall be understood to mean a compound in which at least three aryl or arylene groups are bonded to one another.
Preferred matrix materials for phosphorescent emitters are, as well as the compounds of the formula (I) or (II), 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.
Suitable electron-transporting materials are, for example, the compounds disclosed in Y. Shirota et al., Chem. Rev. 2007, 107(4), 953-1010, or other materials used in these layers according to the prior art.
Materials used for the electron transport layer may be any materials that are used as electron transport materials in the electron transport layer according to the prior art. Especially suitable are aluminium 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 shown in the following table:
Further compounds which, in addition to the compounds of the formula (I) and (II), are preferably used in hole-transporting layers of the OLEDs of the invention are indenofluoreneamine derivatives, amine derivatives, hexaazatriphenylene derivatives, amine derivatives with fused aromatic systems, monobenzoindenofluoreneamines, dibenzoindenofluoreneamines, spirobifluoreneamines, fluoreneamines, spirodibenzopyranamines, dihydroacridine derivatives, spirodibenzofurans and spirodibenzothiophenes, phenanthrenediarylamines, spirotribenzotropolones, spirobifluorenes having meta-phenyldiamine groups, spirobisacridines, xanthenediarylamines, and 9,10-dihydroanthracene spiro compounds having diarylamino groups. Preferred hole-transporting compounds are shown in the following table:
Preferred cathodes of the electronic device are metals having a low work function, metal alloys or multilayer structures composed of various metals, for example alkaline earth metals, alkali metals, main group metals or lanthanoids (e.g. Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.). Additionally suitable are alloys composed of an alkali metal or alkaline earth metal and silver, for example an alloy composed of magnesium and silver. In the case of multilayer structures, in addition to the metals mentioned, it is also possible to use further metals having a relatively high work function, for example Ag or Al, in which case combinations of the metals such as Ca/Ag, Mg/Ag or Ba/Ag, for example, are generally used. It may also be preferable to introduce a thin interlayer of a material having a high dielectric constant between a metallic cathode and the organic semiconductor. Examples of useful materials for this purpose are alkali metal or alkaline earth metal fluorides, but also the corresponding oxides or carbonates (e.g. LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.). It is also possible to use lithium quinolinate (LiQ) for this purpose. The layer thickness of this layer is preferably between 0.5 and 5 nm.
Preferred anodes are materials having a high work function. Preferably, the anode has a work function of greater than 4.5 eV versus vacuum. Firstly, metals having a high redox potential are suitable for this purpose, for example Ag, Pt or Au. Secondly, metal/metal oxide electrodes (e.g. Al/Ni/NiOx, Al/PtOx) may also be preferred. For some applications, at least one of the electrodes has to be transparent or partly transparent in order to enable either the irradiation of the organic material (organic solar cell) or the emission of light (OLED, O-LASER). Preferred anode materials here are conductive mixed metal oxides. Particular preference is given to indium tin oxide (ITO) or indium zinc oxide (IZO). Preference is further given to conductive doped organic materials, especially conductive doped polymers. In addition, the anode may also consist of two or more layers, for example of 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 by a sublimation process. In this case, the materials are applied by vapour deposition in vacuum sublimation systems at an initial pressure of less than 10−5 mbar, preferably less than 10−6 mbar. In this case, however, it is also possible that the initial pressure is even lower, for example less than 10−7 mbar.
Preference is likewise given to an electronic device, characterized in that one or more layers are coated by the OVPD (organic vapour phase deposition) method or with the aid of a carrier gas sublimation. In this case, the materials are applied at a pressure between 10−5 mbar and 1 bar. A special case of this method is the OVJP (organic vapourjet printing) method, in which the materials are applied directly by a nozzle and thus structured (for example M. S. Arnold et al., Appl. Phys. Lett. 2008, 92, 053301).
Preference is additionally given to an electronic device, characterized in that one or more layers are produced from solution, for example by spin-coating, or by any printing method, for example screen printing, flexographic printing, nozzle printing or offset printing, but more preferably LITI (light-induced thermal imaging, thermal transfer printing) or inkjet printing. For this purpose, soluble compounds of formula (I) or (II) are needed. High solubility can be achieved by suitable substitution of the compounds.
It is further preferable that an electronic device of the invention is produced by applying one or more layers from solution and one or more layers by a sublimation method.
After application of the layers, according to the use, the device is structured, contact-connected and finally sealed, in order to rule out damaging effects of water and air.
According to the invention, the electronic devices comprising one or more compounds of formula (I) or (II) can be used in displays, as light sources in lighting applications and as light sources in medical and/or cosmetic applications.
44.6 g (105.2 mmol) of 2,2′-dibromo-4,4′-di-tert-butyl-1,1′-biphenyl is dissolved in 300 ml of dried THE in a baked-out flask. The reaction mixture is cooled to −78° C. At this temperature, 39.3 ml of a 2.5 M solution of n-BuLi in hexane (98.2 mmol) is slowly added dropwise. The mixture is stirred at −70° C. for a further 1 hour. Subsequently, 12.6 g of 9H-fluoren-9-one (70.1 mmol) is dissolved in 300 ml of THE and added dropwise at −70° C. After the addition has ended, the reaction mixture is left to warm up gradually to room temperature, the reaction is stopped with NH4Cl, and then the mixture is concentrated on a rotary evaporator. The solid matter is dissolved in 500 ml of toluene, and then 720 mg (3.8 mmol) of p-toluenesulfonic acid is added. The mixture is heated under reflux for 6 hours, then allowed to cool down to room temperature and admixed with water. The precipitated solids are filtered off with suction and washed with heptane (40.10 g, 68% yield).
The remaining residue is recrystallized from heptane/toluene. The substance is finally sublimed under high vacuum; purity is 99.9% determined by HPLC.
The yield is 19.2 g (54% of theory).
The following compounds are prepared in an analogous manner:
14.6 g of N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-9H-fluorene-2-amine (36.4 mmol) and 4-bromo-2,7-di-tert-butyl-9,9′-spirobi(fluorene) (17.6 g, 34.7 mol) are dissolved in 250 ml of toluene. The solution is degassed and saturated with N2. It is subsequently admixed with 1 g (5.1 mmol) of S-Phos and 1.6 g (1.7 mmol) of Pd2(dba)3 and then 5 g of sodium tert-butoxide (52.05 mmol) is added. The reaction mixture is heated to boiling under a protective atmosphere overnight. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na2SO4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene. The substance is finally sublimed under high vacuum, purity is 99.9% determined by HPLC.
The yield is 7.1 g (25% of theory).
The following compounds are prepared in an analogous manner:
23.5 g (39 mmol) of N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-N-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-9H-fluorene-2-amine and 21.3 g (42 mmol) of 4-bromo-2,7-di-tert-butyl-9,9′-spirobi(fluorene) are suspended in 400 ml of dioxane and 13.7 g of caesium fluoride (90 mmol). 4.0 g (5.4 mmol) of bis(tricyclohexylphosphine)palladium dichloride is added to this suspension, and the reaction mixture is heated under reflux for 18 h. After cooling, the organic phase is removed, filtered through silica gel, washed three times with 80 ml of water and then concentrated to dryness. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene and finally sublimed under high vacuum, purity is 99.9% determined by HPLC.
The yield is 11 g (31% of theory).
The following compounds are prepared in an analogous manner:
10.7 g (69 mmol) of 4-chlorophenylboronic acid, 35 g (69 mmol) of 4-bromo-2,7-di-tert-butyl-9,9′-spirobi(fluorene) and 5.4 g (5 mmol) of Pd(Ph3P)4 are dissolved in 600 ml of THF. The solution is degassed and saturated with N2, and 155 ml of 2 M of potassium carbonate solution is added gradually to this suspension. The reaction mixture is heated to boiling under a protective atmosphere overnight. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na2SO4 and concentrated by rotary evaporation. The residue is purified by crystallization with MeOH. Yield: 25 g (67% of theory). Purity by HPLC>98%.
The following compounds are prepared in an analogous manner:
11.2 g (28 mmol) of N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-9H-fluorene-2-amine and 14.6 g (27 mmol) of the 2,7-di-tert-butyl-5-(4-chlorophenyl)-9,9′-spirobi[fluorene] are dissolved in 225 ml of toluene. The solution is degassed and saturated with N2. It is subsequently admixed with 2.1 ml (2.1 mmol) of tri-tert-butylphosphine solution (1 M in toluene) and 0.98 g (1 mmol) of Pd2(dba)3 and then 5.1 g of sodium tert-butoxide (53 mmol) is added. The reaction mixture is heated to boiling under a protective atmosphere overnight. The mixture is subsequently partitioned between toluene and water, and the organic phase is washed three times with water and dried over Na2SO4 and concentrated by rotary evaporation. After the crude product has been filtered through silica gel with toluene, the remaining residue is recrystallized from heptane/toluene. The substance is finally sublimed under high vacuum; purity is 99.9% determined by HPLC. The yield is 6 g (26% of theory).
The following compounds are prepared in an analogous manner:
Glass plates which have been coated with structured ITO (indium tin oxide) in a thickness of 50 nm form the substrates to which the OLEDs are applied.
The OLEDs basically have the following layer structure: substrate/hole injection layer (HIL)/hole transport layer (HTL1)/optional second hole transport layer (HTL2)/electron blocker layer (EBL)/emission layer (EML)/electron transport layer (ETL1)/optional second electron transport layer (ETL2)/electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminium layer of thickness 100 nm. The exact structure of the OLEDs can be found in the tables which follow. The materials required for production of the OLEDs are shown in a table below.
All materials are applied by thermal vapour deposition in a vacuum chamber. In this case, the emission layer consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as H:SEB (95%:5%) mean here that the material H is present in the layer in a proportion by volume of 95% and SEB in a proportion of 5%.
In an analogous manner, the electron transport layer and the hole injection layer also consist of a mixture of two materials. The structures of the materials that are used in the OLEDs are shown in Table 3.
The OLEDs are characterized in a standard manner. For this purpose, the electroluminescence spectra, the external quantum efficiency (EQE, measured in %) as a function of the luminance, calculated from current-voltage-luminance characteristics assuming Lambertian radiation characteristics, and the lifetime are determined. The parameter EQE @ 10 mA/cm2 refers to the external quantum efficiency which is attained at 10 mA/cm2. The lifetime LT is defined as the time after which the luminance drops from the starting luminance to a certain proportion in the course of operation with constant current density. An LT90 figure means here that the lifetime reported corresponds to the time after which the luminance has dropped to 90% of its starting value. The figure @60 mA/cm2 means here that the lifetime in question is measured at 60 mA/cm2.
OLEDs are produced with the following structure:
OLEDs E1, E2 and E3 show the use of compounds HTM-1, HTM-2 and HTM-3 according to the application in the EBL of blue-fluorescing OLEDs.
The OLEDs show the following values for external quantum efficiency:
OLEDs are produced with the following structure:
OLEDs E4, E5 and E6 show the use of compounds HTM-1, HTM-2 and HTM-3 according to the application in the EBL of green-phophorescing OLEDs.
The OLEDs show the following values for external quantum efficiency:
3) Comparison Between Compound of the Invention and Comparative Compound when Used as HTM in Blue-Fluorescing OLEDs
OLEDs are produced with the following structure:
E7 shows the use of the inventive compound HTM-1 in the HIL and HTL of a blue-fluorescing OLED. E8-comp shows the use of the comparative compound HTM-comp in an otherwise identical construction.
The following results are obtained:
The results show that compound HTM-1 results in distinctly better performance data of the OLED than compound HTM-comp.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20205399.7 | Nov 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/073322 | 8/24/2021 | WO |
