Patent Application
20230225195
The present invention relates to a composition comprising a compound of formula (H1) and a compound of formula (H2). The present invention furthermore relates to a formulation comprising a composition comprising a compound of formula (H1) and a formula (H2) and a solvent. Finally, the present invention relates to an electronic device comprising such a composition.
The development of functional compounds for use in electronic devices is currently the subject of intensive research. The aim is, in particular, the development of compounds with which improved properties of electronic devices in one or more relevant points can be achieved, such as, for example, power efficiency and lifetime of the device as well as colour coordinates of the emitted light.
In accordance with the present invention, the term electronic device is taken to mean, inter alia, organic integrated circuits (OICs), organic field-effect transistors (OFETs), organic thin-film transistors (OTFTs), organic light-emitting transistors (OLETs), organic solar cells (OSCs), organic optical detectors, organic photoreceptors, organic field-quench devices (OFQDs), organic light-emitting electrochemical cells (OLECs), organic laser diodes (O-lasers) and organic electroluminescent devices (OLEDs).
Of particular interest is the provision of compounds for use in the lastmentioned electronic devices called OLEDs. The general structure and the functional principle of OLEDs are known to the person skilled in the art and are described, for example, in U.S. Pat. No. 4,539,507.
Further improvements are still necessary with respect to the performance data of OLEDs, in particular with a view to broad commercial use, for example in display devices or as light sources. Of particular importance in this connection are the lifetime, the efficiency and the operating voltage of the OLEDs and as well as the colour values achieved. In particular, in case of blue-emitting OLEDs, there is potential for improvement with respect to the efficiency, lifetime and operating voltage of the devices.
An important starting point for achieving the said improvements is the choice of the emitter compound and of the host compound. Indeed, the emitter compound is generally employed in the emitting layer in combination with a second compound, which serves as matrix compound or host compound. An emitter compound here is taken to mean a compound which emits light during operation of the electronic device. A host compound in this case is taken to mean a compound which is present in the mixture in a greater proportion than the emitter compound. The term matrix compound and the term host compound can be used synonymously. The host compound preferably does not emit light. Even if a plurality of different host compounds are present in the mixture of the emitting layer, their individual proportions are typically greater than the proportion of the emitter compounds, or the proportions of the individual emitter compounds if a plurality of emitter compounds are present in the mixture of the emitting layer.
Such embodiments have been described for fluorescent emitting layers for example in U.S. Pat. No. 4,769,292.
If a mixture of a plurality of compounds is present in the emitting layer, the emitter compound is typically the component present in smaller amount, i.e.
In a smaller proportion than the other compounds present in the mixture of the emitting layer. In this case, the emitter compound is also referred to as dopant.
Hosts compounds for fluorescent emitters that are known from the prior art are a multiplicity of compounds. The emitting layer may comprise one host compounds or more.
Host compounds comprising phenanthrene groups have been disclosed in the prior art (for example in WO 2009/100925). Host compounds comprising benzanthracene groups have also been disclosed in the prior art (for example in WO 2015/158409).
However, there is still a need for further host materials for fluorescent emitters, which may be employed in OLEDs and lead to OLEDs having very good properties in terms of lifetime, color emission and efficiency. More particularly, there is a need for host materials for fluorescent emitters combining very high efficiencies, very good lifetime and very good thermal stability.
Furthermore, it is known that an OLED may comprise different layers, which may be applied either by vapour deposition in a vacuum chamber or by processing from a solution. The processes based on vapour deposition lead to very good results, but they might be complex and expensive. Therefore, there is also a need for compositions comprising OLED materials that can be easily and reliably processed from a solution. More particularly, there is a need for compositions comprising OLED materials that can be deposited as homogeneous films during the fabrication of OLEDs when processed from a formulation, more particularly from a solution like an ink. In this case, the materials should have good solubility properties in the solution that comprises them and the deposited films comprising OLED materials should be as smooth as possible after the drying step leading to the removing of the solvent. It is important that the deposited layer form a smooth and homogenous film as layer thickness inhomogeneities cause uneven luminance distributions with areas of thinner film thickness showing increased luminance and thicker areas with reduced luminance, which leads to a decrease of the OLED's quality. At the same time, the OLEDs comprising the films processed form a solution should exhibit good performances, for example in terms of lifetime, operating voltage and efficiency.
There is furthermore still a need for processes, which lead to stable OLED materials, which are easily purified and easily processed. There is a need for processes, which are economically and qualitatively interesting by providing OLED materials in acceptable purity and with a high yield.
The present invention is thus based on the technical object of providing compositions comprising OLED materials, which are suitable for use in electronic devices, such as OLEDs, more particularly as a matrix component for fluorescent emitters. The present invention is also based on the technical object of providing compositions comprising OLED materials, which are particularly suitable for solution processing. The present invention is also based on the technical object of providing processes.
In investigations on novel compositions for use in electronic devices, it has now been found, that the compositions comprising a compound of formula (H1) and a compound of formula (H2) as defined below are eminently suitable for use in electronic devices. In particular, they achieve one or more, preferably all, of the above-mentioned technical objects.
The present application thus relates to a composition comprising a compound of formula (H1) and a compound of formula (H2),
Adjacent substituents in the sense of the present invention are substituents which are bonded to atoms which are linked directly to one another or which are bonded to the same atom.
Furthermore, the following definitions of chemical groups apply for the purposes of the present application:
An aryl group in the sense of this invention contains 6 to 60 aromatic ring atoms, preferably 6 to 40 aromatic ring atoms, more preferably 6 to 20 aromatic ring atoms; a heteroaryl group in the sense of this invention contains 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, more preferably 5 to 20 aromatic ring atoms, at least one of which is a heteroatom. The heteroatoms are preferably selected from N, O and S. This represents the basic definition. If other preferences are indicated in the description of the present invention, for example with respect to the number of aromatic ring atoms or the heteroatoms present, these apply.
An aryl group or heteroaryl group here is taken to mean either a simple aromatic ring, i.e. benzene, or a simple heteroaromatic ring, for example pyridine, pyrimidine or thiophene, or a condensed (annellated) aromatic or heteroaromatic polycycle, for example naphthalene, phenanthrene, quinoline or carbazole. A condensed (annellated) aromatic or heteroaromatic polycycle in the sense of the present application consists of two or more simple aromatic or heteroaromatic rings condensed with one another.
An aryl or heteroaryl group, which may in each case be substituted by the above-mentioned radicals and which may be linked to the aromatic or heteroaromatic ring system via any desired positions, is taken to mean, in particular, groups derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, fluoranthene, benzanthracene, benzophenanthrene, tetracene, pentacene, benzopyrene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalininidazole, oxazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, pyrazine, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole.
An aryloxy group in accordance with the definition of the present invention is taken to mean an aryl group, as defined above, which is bonded via an oxygen atom. An analogous definition applies to heteroaryloxy groups.
An aromatic ring system in the sense of this invention contains 6 to 60 C atoms in the ring system, preferably 6 to 40 C atoms, more preferably 6 to 20 C atoms. A heteroaromatic ring system in the sense of this invention contains 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, more preferably 5 to 20 aromatic ring atoms, at least one of which is a heteroatom. The heteroatoms are preferably selected from N, O and/or S. An aromatic or heteroaromatic ring system in the sense of this invention is intended to be taken to mean a system which does not necessarily contain only aryl or heteroaryl groups, but instead in which, in addition, a plurality of aryl or heteroaryl groups may be connected by a non-aromatic unit (preferably less than 10% of the atoms other than H), such as, for example, an sp3-hybridised C, Si, N or O atom, an sp2-hybridised C or N atom or an sp-hybridised C atom. Thus, for example, systems such as 9,9′-spirobifluorene, 9,9′-diarylfluorene, triarylamine, diaryl ether, stilbene, etc., are also intended to be taken to be aromatic ring systems in the sense of this invention, as are systems in which two or more aryl groups are connected, for example, by a linear or cyclic alkyl, alkenyl or alkynyl group or by a silyl group. Furthermore, systems in which two or more aryl or heteroaryl groups are linked to one another via single bonds are also taken to be aromatic or heteroaromatic ring systems in the sense of this invention, such as, for example, systems such as biphenyl, terphenyl or diphenyltriazine.
An aromatic or heteroaromatic ring system having 5-60 aromatic ring atoms, which may in each case also be substituted by radicals as defined above and which may be linked to the aromatic or heteroaromatic group via any desired positions, is taken to mean, in particular, groups derived from benzene, naphthalene, anthracene, benzanthracene, phenanthrene, benzophenanthrene, pyrene, chrysene, perylene, fluoranthene, naphthacene, pentacene, benzopyrene, biphenyl, biphenylene, terphenyl, terphenylene, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene, truxene, isotruxene, spirotruxene, spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, indolocarbazole, indenocarbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, oxazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, 1,5-diazaanthracene, 2,7-diazapyrene, 2,3-diazapyrene, 1,6-diazapyrene, 1,8-diazapyrene, 4,5-diazapyrene, 4,5,9,10-tetraazaperylene, pyrazine, phenazine, phenoxazine, phenothiazine, fluorubin, naphthyridine, azacarbazole, benzocarboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole, or combinations of these groups.
For the purposes of the present invention, a straight-chain alkyl group having 1 to 40 C atoms or a branched or cyclic alkyl group having 3 to 40 C atoms or an alkenyl or alkynyl group having 2 to 40 C atoms, in which, in addition, individual H atoms or CH2 groups may be substituted by the groups mentioned above under the definition of the radicals, is preferably taken to mean the radicals methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, neohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexy, trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl or octynyl. An alkoxy or thioalkyl group having 1 to 40 C atoms is preferably taken to mean methoxy, trifluoromethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, s-pentoxy, 2-methylbutoxy, n-hexoxy, cyclohexyloxy, n-heptoxy, cycloheptyloxy, n-octyloxy, cyclooctyloxy, 2-ethylhexyloxy, pentafluoroethoxy, 2,2,2-trifluoroethoxy, methylthio, ethylthio, n-propylthio, i-propylthio, n-butylthio, i-butylthio, s-butylthio, t-butylthio, n-pentylthio, s-pentylthio, n-hexylthio, cyclohexylthio, n-heptylthio, cycoheptylthio, n-octylthio, cyclooctylthio, 2-ethylhexylthio, trifluoromethylthio, pentafluoroethylthio, 2,2,2-trifluoroethylthio, ethenylthio, propenylthio, butenylthio, pentenylthio, cyclopentenylthio, hexenylthio, cyclohexenylthio, heptenylthio, cycloheptenylthio, octenylthio, cyclooctenylthio, ethynylthio, propynylthio, butynylthio, pentynylthio, hexynylthio, heptynylthio or octynylthio.
The formulation that two or more radicals may form a ring with one another is, for the purposes of the present application, intended to be taken to mean, inter alia, that the two radicals are linked to one another by a chemical bond. This is illustrated by the following schemes:
Furthermore, however, the above-mentioned formulation is also intended to be taken to mean that, in the case where one of the two radicals represents hydrogen, the second radical is bonded at the position to which the hydrogen atom was bonded, with formation of a ring. This is illustrated by the following scheme:
Preferably, the groups Ar1 and Ar3 stand on each occurrence, identically or differently, for an anthracene, phenanthrene, pyrene, chrysene, perylene, fluoranthene, benzanthracene, benzophenanthrene, tetracene or pentacene, each of which may in each case be substituted by one or more radicals RV at any free positions for Ar1 or by one or more radicals RY at any free positions for Ar3
Preferably, the groups Ar1, Ar3 stand on each occurrence, identically or differently, for a condensed aryl group having 10 to 18 aromatic ring atoms. More preferably, the groups Ar1, Ar3 stand on each occurrence, identically or differently, for an anthracene, naphthalene, phenanthrene, tetracene, chrysene, benzanthracene, benzophenanthracene, pyrene, perylene, triphenylene, benzopyrene or fluoranthene, each of which may be substituted by one or more radicals RV in the case of Ar1 or RY in the case of Ar3 at any free positions. Very preferably, the groups Ar1, Ar3 stand for an anthracene group, which may be substituted by one or more radicals RV at any free positions for Ar1 or by one or more radicals RY at any free positions for Ar3.
Examples of suitable groups Ar1 and Ar3 are the groups of formulae (Ar1-1) to (Ar1-11) as represented in the table below:
where
the dashed bonds indicate the bonding to the adjacent groups; and where the groups of formulae (Ar1-1) to (Ar1-11) may be substituted at each free position by a group RV in the case of Ar1 or by a group RY in the case of Ar3, where RV and RY have the same meaning as above.
Among the groups of formulae (Ar1-1) to (Ar1-11), the group of formula (Ar1-1) is preferred.
Examples of very suitable groups Ar1 and Ar3 are the groups of formulae (Ar1-1-1) to (Ar1-12-1) as represented in the table below:
where
the dashed bonds indicate the bonding to the adjacent groups; and where the groups of formulae (Ar1-1-1) to (Ar1-12-1) may be substituted at each free position by a group RV in the case of Ar1 or by a group RY in the case of Ar3, where RV and RY have the same meaning as above.
Among the groups of formulae (Ar1-1-1) to (Ar1-12-1), the group of formula (Ar1-1-1) is preferred.
Preferably, the compound of formula (H2) is selected from the compounds of formula (H2-1),
where the symbol Ar2 and Z have the same meaning as above; and where
Y is CRY or N; or Y is C if bonded to Ar2 or a group Z; where RY has the same meaning as above.
More preferably, the compound of formula (H2) is selected from the compounds of formula (H2-2),
where Ar2, Y, Z have the same meaning as above.
Even more preferably, the compound of formula (H2) is selected from the compounds of formula (H2-3),
where the symbols have the same meaning as above and with the proviso that the group CRZ correspond to a group C at the bonding position of the adjacent anthracene.
Particularly preferably, the compound of formula (H2) is selected from the compounds of formula (H2-4),
where the symbols have the same meaning as above.
Very particularly preferably, the compound of formula (H2) is selected from the compounds of formula (H2-5),
where the symbols have the same meaning as above.
Examples of very suitable compounds of formula (H2-5) are the compounds ((H2-5-1) to (H2-5-4),
where the symbols have the same meaning as above.
Preferably, RY, RZ stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, O or S and where one or more H atoms may be replaced by D or F, an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, RY, RZ stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 6 C atoms or branched or a cyclic alkyl group having 3 to 20, preferably 3 to 10, more preferably 3 to 6 C atoms, each of which may be substituted by one or more radicals R, an aromatic or heteroaromatic ring system having 5 to 40, preferably 5 to 30, more preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
Particularly preferably, RY stands for H.
Particularly preferably, RZ stands on each occurrence, identically or differently, for a straight-chain alkyl group having 1 to 10, more preferably 1 to 6 C atoms or branched or a cyclic alkyl group having 3 to 10, more preferably 3 to 6 C atoms, each of which may be substituted by one or more radicals R, an aromatic or heteroaromatic ring system having 5 to 40, preferably 5 to 30, more preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
Preferably, the compound of formula (H1) is selected from the compounds of formula (H1-1),
where the symbols X, ArS, Ar4 and the indices a and b have the same meaning as above; and
V is CRV or N; or V is C if bonded to Ar4, ArS or a group X; where RV has the same meaning as above.
Preferably, the indices a and b are equal to 0, so that the group ArS is absent and the anthracene moiety is directly bonded to the phenanthrene moiety.
Preferably, the group ArS stands on each occurrence, identically or differently, for phenyl, biphenyl, fluorene, spirobifluorene, naphthalene, phenanthrene, anthracene, dibenzofuran, dibenzothiophene, carbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, benzopyridine, benzopyridazine, benzopyrimidine and quinazoline, each of which may be substituted by one or more radicals R.
Examples of suitable groups ArS are the groups of formulae (ArS-1) to (ArS28) as represented in the table below:
where the dashed bonds indicate the bonding to the adjacent groups in formula (1);
where the groups of formulae (ArS-1) to (ArS-26) may be substituted at each free position by a group R, which has the same meaning as defined above; and
where the group E is on each occurrence, identically or differently, selected from —BR0—, —C(R0)2—, —Si(R0)2—, —C(═O)—, —O—, —S—, —S(═O)—, —SO2—, —N(R0)—, and —P(R0)—,
where R0 stands on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 20, preferably 1 to 10 C atoms or branched or a cyclic alkyl group having 3 to 20, preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by 0 or S and where one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring systems having 5 to 40, preferably 5 to 30, more preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R, where two adjacent radicals R0, may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R.
Among the groups of formulae (ArS-1) to (ArS-26), the groups of formulae (ArS-1), (ArS-2), (ArS-3), (ArS-11) and (ArS-12) are preferred. The groups of formula (ArS-1), (ArS-2), (ArS-3) are very preferred.
More preferably, the compound of formula (H1) is selected from the compounds of formula (H1-2),
where X, Ar4 and V have the same meaning as above.
Even more preferably, the compound of formula (H1) is selected from the compounds of formula (H1-3),
where the symbols have the same meaning as above.
Particularly preferably, the compound of formula (H1) is selected from the compounds of formula (H1-4),
where the symbols have the same meaning as above.
Very particularly preferably, the compound of formula (H1) is selected from the compound of formula (H1-5),
where the symbols have the same meaning as in claim 1.
Examples of very suitable compounds of formula (H1-5) are the compounds (H1-5-1) to (H1-5-4),
where the symbols have the same meaning as above.
Preferably, RX, RV stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by RC═CR, C≡C, O or S and where one or more H atoms may be replaced by D or F, an aromatic or heteroaromatic ring system having 5 to 60, preferably 5 to 40, more preferably 5 to 30, particularly preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, RX, RV stand on each occurrence, identically or differently, for H, D, F, a straight-chain alkyl group having 1 to 20, preferably 1 to 10, more preferably 1 to 6 C atoms or branched or a cyclic alkyl group having 3 to 20, preferably 3 to 10, more preferably 3 to 6 C atoms, each of which may be substituted by one or more radicals R, an aromatic or heteroaromatic ring system having 5 to 40, preferably 5 to 30, more preferably 5 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
More preferably, RX, RV stand on each occurrence, identically or differently, for H, a straight-chain alkyl group having 1 to 10, more preferably 1 to 6 C atoms or branched or a cyclic alkyl group having 3 to 10, more preferably 3 to 6 C atoms, each of which may be substituted by one or more radicals R, an aromatic or heteroaromatic ring system having 5 to 40, preferably 5 to 30, more preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R.
Preferably, the groups Ar2, Ar4 are on each occurrence, identically or differently, selected from aromatic or heteroaromatic ring systems having 5 to 30, preferably 5 to 25 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, the group Ar2, Ar4 are selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, phenanthrene, anthracene, triphenylene, fluoranthene, tetracene, chrysene, benzanthracene, benzophenanthracene, pyrene, perylene, indole, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, carbazole, indenocarbazole, indolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, quinolone, benzopyridine, benzopyridazine, benzopyrimidine, benzimidazole and quinazoline, each of which may be substituted by one or more radicals R; where Ar2, Ar4 might also be a combination of two or more of the previously cited groups. Particularly preferably, the groups Ar2, Ar4 are selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, triphenylene, fluoranthene, tetracene, chrysene, benzanthracene, benzophenanthracene, pyrene or perylene, dibenzofuran, carbazole and dibenzothiophene, each of which may be substituted by one or more radicals R at any free positions; and where Ar2, Ar4 might also be a combination of two or more of the previously cited groups. Very particularly preferably, the groups Ar2, Ar4 are selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, triphenylene, fluoranthene, dibenzofuran, carbazole and dibenzothiophene, each of which may be substituted by one or more radicals R at any free positions; and where Ar2, Ar4 might also be a combination of two or more of the previously cited groups.
Examples of suitable groups Ar2 and Ar4 are the groups of formulae (Ar2-1) to (Ar2-27) as depicted in the table below:
where the dashed bond indicates the bonding to the adjacent group and where the group R0 has the same meaning as above; and where the groups of formulae (Ar2-1) to (Ar2-27) may be substituted at each free position by a group R, which has the same meaning as above.
Among the groups of formulae (Ar2-1) to (Ar2-27), the groups of formulae (Ar2-1), (Ar2-2), (Ar2-3), (Ar2-4), (Ar2-5), (Ar2-8), (Ar2-18), (Ar2-19) are preferred. The groups of formula (Ar2-1), (Ar2-2), (Ar2-3), (Ar2-4), (Ar2-5) are very preferred.
Preferably, R stands on each occurrence, identically or differently, for H, D, F, CN, N(Ar)2, a straight-chain alkyl, alkoxy or thioalkyl groups having 1 to 40, preferably 1 to 20, more preferably 1 to 10 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl groups having 3 to 40, preferably 3 to 20, more preferably 3 to 10 C atoms, each of which may be substituted by one or more radicals R′, where in each case one or more non-adjacent CH2 groups may be replaced by R′C═CR′, C≡C, O or S and where one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring systems having 5 to 80, preferably 5 to 40, more preferably 5 to 30, particularly preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R′.
Preferably, R′ stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CN, a straight-chain alkyl group having 1 to 10 C atoms or branched or cyclic alkyl group having 3 to 10 C atoms, where in each case one or more H atoms may be replaced by D or F, or an aromatic or heteroaromatic ring system having 5 to 18 C atoms.
The following compounds are examples of compounds of formula (H11):
The following compounds are examples of compounds of formula (H2):
In accordance with a preferred embodiment, the composition comprises a compound of formula (H1), a compound of formula (H2) and at least one fluorescent emitter. The expression “at least one fluorescent emitter” means “one, two, three or more fluorescent emitters”.
Preferably, the composition comprises at least one fluorescent emitter, which comprises at least one of the following group:
More preferably, the composition comprises at least one fluorescent emitter of formula (E-1),
Preferably, the fluorescent emitter of formula (E-1) comprises at least one group Ar10, Ar11 or Ar12, preferably Ar10, which is selected from the groups of formulae (Ar10-1) to (Ar10-24):
In accordance with a preferred embodiment, the emitters of formula (E-1) comprise a group Ar10 selected from the groups of formulae (Ar10-15) to (Ar10-22), wherein d is preferably equal to 1 and wherein preferably at least one group Ar11, Ar12 is selected from the groups of formulae (Ar10-15) to (Ar10-22).
In accordance with a very preferred embodiment, the fluorescent emitter of formula (E-1) is selected from the emitters of formulae (E-1-1) to (E-1-6),
where the symbols have the same meaning as above and where:
f is 0, 1 or 2; and
the benzene rings represented above in the compounds of formulae (E-1-1) to (E-1-6) may be substituted at all free positions by one or more radicals R,
Particularly preferably, the fluorescent emitter of formula (E-1) is selected from the compounds of formulae (E-1-1-A) to (E-1-6-A),
where the symbols and indices have the same meaning as above and where the benzene rings represented above in the compounds of formulae (E-1-1-A) to (E-1-85-A) may be substituted at all free positions by one or more radicals R.
Preferably, the fluorescent emitter of formula (E-2) is selected from fluorescent emitters of formula (E-2-1) to (E-2-43),
where the groups of formulae (E-2-1) to (E-2-43) may be substituted at all free positions by one or more radicals R; and where E20 has the same definition as above. Preferably, E20 is C(R0)2.
The fluorescent emitters of formula (E-2) are preferably selected from the compounds of formulae (E-2-32) to (E-2-43). More preferably, the compounds of formula (E-2) are selected from the compounds (E-2-32-A) to (E-2-43-A):
where the symbols have the same meaning as above and where the benzene and naphthalene rings represented above in the compounds of formulae (E-2-32-A) to (E-2-43-A) may be substituted at all free positions by one or more radicals R.
Preferably, the fluorescent emitter of formula (E-3) is selected from fluorescent emitters of formula (E-3-1),
where the symbols and indices have the same meaning as above.
More preferably, the fluorescent emitter of formula (E-3) is selected from fluorescent emitters of formula (E-3-2),
where the symbols E30 to E33 have the same meaning as above; where t is 0 or 1, wherein when t is 0, the group E32 is absent and radicals R30 are present, which replace the bonds to E32; and where
R10 stands on each occurrence, identically or differently, for H, D, F, Cl, Br, I, CHO, CN, C(═O)Ar, P(═O)(Ar)2, S(═O)Ar, S(═O)2Ar, N(R′)2, N(Ar)2, NO2, Si(R′)3, B(OR′)2, OSO2R′, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 C atoms or branched or a cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 C atoms, each of which may be substituted by one or more radicals R, where in each case one or more non-adjacent CH2 groups may be replaced by R′C═CR′, C≡C, Si(R′)2, Ge(R′)2, Sn(R′)2, C═O, C═S, C═Se, P(═O)(R′), SO, SO2, O, S or CONR′ and where one or more H atoms may be replaced by D, F, Cl, Br, I, CN or NO2, an aromatic or heteroaromatic ring system having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R′, or an aryloxy group having 5 to 60 aromatic ring atoms, which may be substituted by one or more radicals R′; where two adjacent substituents R10 may form an aliphatic or aromatic ring system together, which may be substituted by one or more radicals R′; where R′ has the same definition as above.
Even more preferably, the fluorescent emitter of formula (E-3) is selected from fluorescent emitters of formula (E-3-3) and (E-3-4),
where the symbols and indices have the same meaning as above.
In accordance with a preferred embodiment, the fluorescent emitter of formula (E-1), (E-2) or (E-3), comprises a group RS, wherein the group RS is selected:
where the dashed bond in formula (RS-e) indicates the bonding to the fluorescent emitter, where Ar50, Ar51 stand on each occurrence, identically or differently, for an aromatic or heteroaromatic ring systems having 5 to 60 aromatic ring atoms, which may in each case be substituted by one or more radicals R; and where m is an integer selected from 1 to 10.
Preferably, the index m in the group of formula (RS-e) is an integer selected from 1 to 6, very preferably from 1 to 4.
Preferably, where Ar50, Ar51 stand on each occurrence, identically or differently, for an aromatic or heteroaromatic ring systems having 5 to 40, preferably 5 to 30, more preferably 6 to 18 aromatic ring atoms, which may in each case be substituted by one or more radicals R. More preferably, Ar50, Ar51 are selected from phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, anthracene, phenanthrene, triphenylene, fluoranthene, dibenzofuran, carbazole and dibenzothiophene, which may in each case be substituted by one or more radicals R. Very preferably, at least one group Ar50 or Ar51 is a fluorene, which may be substituted by one or more radicals R.
More particularly, it is preferred that at least one group Ar50 stands for a group of formula (Ar50-2) and/or at least one group Ar51 stands for a group of formula (Ar51-2),
where
the dashed bonds in formula (Ar50-2) indicate the bonding to the fluorescent emitter and to a group Ar50 or Ar51; and the dashed bond in formula (Ar51-2) indicates the bonding to Ar50;
The group RS is preferably located at a position, where it replaces R, R0 or R′.
Examples of fluorescent emitters which may be employed in the composition comprising the compounds of formulae (H1) and (H2) are aromatic anthracenamines, aromatic anthracenediamines, aromatic pyrenamines, aromatic pyrenediamines, aromatic chrysenamines or aromatic chrysenediamines. An aromatic anthracenamine is taken to mean a compound in which one diarylamino group is bonded directly to an anthracene group, preferably in the 9-position. An aromatic anthracenediamine is taken to mean a compound in which two diarylamino groups are bonded directly to an anthracene group, preferably in the 9,10-position. Aromatic pyrenamines, pyrenediamines, chrysenamines and chrysenediamines are defined analogously thereto, where the diarylamino groups are preferably bonded to the pyrene in the 1-position or in the 1,6-position. Further preferred emitters are indenofluorenamines or indenofluorenediamines, for example in accordance with WO 2006/108497 or WO 2006/122630, benzoindenofluorenamines or benzoindenofluorenediamines, for example in accordance with WO 2008/006449, and dibenzoindenofluorenamines or dibenzoindenofluorenediamines, for example in accordance with WO 2007/140847, and the indenofluorene derivatives containing condensed aryl groups which are disclosed in WO 2010/012328. Still further preferred emitters are benzanthracene derivatives as disclosed in WO 2015/158409, anthracene derivatives as disclosed in WO 2017/036573, fluorene dimers connected via heteroaryl groups like in WO 2016/150544 or phenoxazine derivatives as disclosed in WO 2017/028940 and WO 2017/028941. Preference is likewise given to the pyrenarylamines disclosed in WO 2012/048780 and WO 2013/185871. Preference is likewise given to the benzoindenofluorenamines disclosed in WO 2014/037077, the benzofluorenamines disclosed in WO 2014/106522 and the indenofluorenes disclosed in WO 2014/111269 or WO 2017/036574, WO 2018/007421. Also preferred are the emitters comprising dibenzofuran or indenodibenzofuran moieties as disclosed in WO 2018/095888, WO 2018/095940, WO 2019/076789, WO 2019/170572 as well as in the unpublished applications PCT/EP2019/072697, PCT/EP2019/072670 and PCT/EP2019/072662. Preference is likewise given to boron derivatives as disclosed, for example, in WO 2015/102118, CN108409769, CN107266484, WO2017195669, US2018069182 as well as in the unpublished applications EP 19168728.4, EP 19199326.0 and EP 19208643.7.
In the case of the present invention, very suitable fluorescent emitters are the indenofluorene derivatives disclosed in WO 2018/007421 and the dibenzofuran derivatives disclosed in WO 2019/076789.
Examples of preferred fluorescent emitting compounds, which may be employed in the composition comprising the compounds of formulae (H1) and (H2) are depicted in the following table:
In accordance with the invention, the compound of formula (H1) and the compound of formula (H2) are present together in the composition, preferably in a homogeneous mixture.
Preferably, the compound of formula (H1) is present in the composition according to the invention in a proportion of 1-60%, preferably 5-50%, more preferably 10-50%, particularly preferably 5-40%, more particularly preferably 10-40%, and very more particularly preferably 20-40%.
Preferably, the compound of formula (H2) is present in the composition in a proportion of 30-99%, preferably 50-95%, more preferably 50-90%, particularly preferably 60-95%, more particularly preferably 60-90% and very more particularly preferably 60-80%.
According to a preferred embodiment, the composition according to the invention further comprises at least one fluorescent emitter. In this case, it is preferred that the fluorescent emitter is present in the composition in a proportion of 0.1 and 50.0%, preferably between 0.5 and 20.0%, particularly preferably between 1.0 and 10.0%.
The specifications of the proportions in % are, for the purposes of the present application, taken to mean % by vol. if the compounds are applied from the gas phase and % by weight if the compounds are applied from solution.
For the processing of the compounds according to the invention from the liquid phase, for example by coating processes like spin coating or by printing processes, formulations of the compositions according to the invention are necessary. These formulations can be, for example, solutions, dispersions or emulsions. It may be preferred to use mixtures of two or more solvents for this purpose. The solvents are preferably selected from organic and inorganic solvents, more preferably organic solvents. The solvents are very preferably selected from hydrocarbons, alcohols, esters, ethers, ketones and amines. Suitable and preferred solvents are, for example, toluene, anisole, o-, m- or p-xylene, methyl benzoate, mesitylene, tetralin, veratrole, THF, methyl-THF, THP, chlorobenzene, dioxane, phenoxytoluene, in particular 3-phenoxytoluene, (−)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 1-ethylnaphthalene, decylbenzene, phenyl naphthalene, menthyl isovalerate, para tolyl isobutyrate, cyclohexal hexanoate, ethyl para toluate, ethyl ortho toluate, ethyl meta toluate, decahydronaphthalene, ethyl 2-methoxybenzoate, dibutylaniline, dicyclohexylketone, isosorbide dimethyl ether, decahydronaphthalene, 2-methylbiphenyl, ethyl octanoate, octyl octanoate, diethyl sebacate, 3,3-dimethylbiphenyl, 1,4-dimethylnaphthalene, 2,2′-dimethylbiphenyl, 2-methylbenzothiazole, 2-phenoxyethanol, 2-pyrrolidinone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, acetophenone, α-terpineol, benzothiazole, butyl benzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene, decalin, dodecylbenzene, ethyl benzoate, indane, NMP, p-cymene, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethylene glycol butyl methyl ether, triethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, diethylene-glycol monobutyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane or mixtures of these solvents.
The present invention therefore furthermore relates to a formulation comprising a compound formula (H1) and a compound of formula (H2) according to the invention and at least one solvent. The solvent may be one of the above-mentioned solvents or a mixture of these solvents.
The proportion of the organic solvent in the formulation according to the invention is preferably at least 60% by weight, preferably at least 70% by weight and more preferably at least 80% by weight, based on the total weight of the formulation.
A formulation in accordance with the present invention can be employed for the production of a layer or multilayered structure in which the organofunctional materials are present in layers, as are required for the production of preferred electronic or opto-electronic components, such as OLEDs.
The formulation of the present invention can preferably be employed for the formation of a functional layer comprising a composition according to the present invention on a substrate or on one of the layers applied to the substrate.
Still further object of the invention is a process for the production of an electronic device, wherein at least one layer is obtained from the application of a formulation of the present invention. Preferably, a formulation according to the invention is applied to a substrate or to another layer and then dried.
The functional layer obtained from the formulation according to the invention can be produced, for example, by flood coating, dip coating, spray coating, spin coating, screen printing, relief printing, gravure printing, rotary printing, roller coating, flexographic printing, offset printing or nozzle printing, preferably ink-jet printing on a substrate or one of the layers applied to the substrate.
After the application of a formulation according to the invention to a substrate or a functional layer already applied, a drying step can be carried out in order to remove the solvent. The drying can preferably be carried out at relatively low temperature and over a relatively long period in order to avoid bubble formation and to obtain a uniform coating. The drying can preferably be carried out at a temperature in the range from 80 to 300° C., particularly preferably 150 to 250° C. and especially preferably 180 to 200° C. The drying here can preferably be carried out at a pressure in the range from 10−8 mbar to 2 bar, particularly preferably in the range from 10−2 mbar to 1 bar and especially preferably in the range from 10−1 mbar to 100 mbar. The duration of the drying depends on the degree of drying to be achieved, where small amounts of water can optionally be removed at relatively high temperature and in combination with sintering, which is preferably to be carried out.
Therefore, the present invention relates to a process for the production of an electronic device comprising at least one layer comprising a composition according to the present invention, wherein the process comprises the following steps:
a) Preparation of a formulation according to the invention;
b) Application of the formulation prepared in step a) on a substrate or on another layer in order to form a layer comprising a composition according to the present invention;
c) Drying of the layer in order to remove the solvent.
Preferably, in step b), the formulation is applied by processing from a liquid phase, more preferably via a coating method or a printing method, very more preferably by a printing method, particularly preferably by an inkjet printing method.
Another object of the invention is an electronic device, which comprises anode, cathode and at least one functional layer in between, where this functional layer comprises a composition according to the invention. Preferably, the at least one functional layer comprising a composition according to the invention is an emitting layer.
The electronic device is preferably selected from organic electroluminescent device (OLEDs), organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, dye-sensitised organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light-emitting electrochemical cells, organic laser diodes and organic plasmon emitting devices. More preferably, the electronic device is an organic electroluminescent device (OLED).
The organic electroluminescent device comprises a cathode, an anode and at least one emitting layer, which comprises a composition according to the invention. Apart from these layers, it may also comprise further layers, for example in each case one or more hole-injection layers, hole-transport layers, hole-blocking layers, electron-transport layers, electron-injection layers, exciton-blocking layers, electron-blocking layers and/or charge-generation layers. It is likewise possible for interlayers, which have, for example, an exciton-blocking function, to be introduced between two emitting layers. However, it should be pointed out that each of these layers does not necessarily have to be present. The organic electroluminescent device here may comprise one emitting layer or a plurality of emitting layers. If a plurality of emission layers are present, these preferably have in total a plurality of emission maxima between 380 nm and 750 nm, resulting overall in white emission, i.e. various emitting compounds which are able to fluoresce or phosphoresce are used in the emitting layers. Particular preference is given to systems having three emitting layers, where the three layers exhibit blue, green and orange or red emission (for the basic structure see, for example, WO 2005/011013). These can be fluorescent or phosphorescent emission layers or hybrid systems, in which fluorescent and phosphorescent emission layers are combined with one another.
The electronic device concerned may comprise a single emitting layer comprising the composition according to the invention or it may comprise two or more emitting layers.
The composition according to the present invention may comprise one or more further matrix materials.
Preferred further matrix materials are selected from the classes of the oligoarylenes (for example 2,2′,7,7′-tetraphenylspirobifluorene in accordance with EP 676461 or dinaphthylanthracene), in particular the oligoarylenes containing condensed aromatic groups, the oligoarylenevinylenes (for example DPVBi or spiro-DPVBi in accordance with EP 676461), the polypodal metal complexes (for example in accordance with WO 2004/081017), the hole-conducting compounds (for example in accordance with WO 2004/058911), the electron-conducting compounds, in particular ketones, phosphine oxides, sulfoxides, etc. (for example in accordance with WO 2005/084081 and WO 2005/084082), the atropisomers (for example in accordance with WO 2006/048268), the boronic acid derivatives (for example in accordance with WO 2006/117052) or the benzanthracenes (for example in accordance with WO 2008/145239). 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 sense of this invention is intended to be taken to mean a compound in which at least three aryl or arylene groups are bonded to one another.
Generally preferred classes of material for use as corresponding functional materials in the organic electroluminescent devices according to the invention are indicated below.
Suitable charge-transport materials, as can be used in the hole-injection or hole-transport layer or electron-blocking layer or in the electron-transport layer of the electronic device according to the invention, are, for example, the compounds disclosed in Y. Shirota et al., Chem. Rev. 2007, 107(4), 953-1010, or other materials as are employed in these layers in accordance with the prior art.
Materials which can be used for the electron-transport layer are all materials as are used in accordance with the prior art as electron-transport materials in the electron-transport layer. Particularly suitable are aluminium complexes, for example Alq3, zirconium complexes, for example Zrq4, 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. Furthermore, suitable materials are derivatives of the above-mentioned compounds, as disclosed in JP 2000/053957, WO 2003/060956, WO 2004/028217, WO 2004/080975 and WO 2010/072300.
Preferred hole-transport materials which can be used in a hole-transport, hole-injection or electron-blocking layer in the electroluminescent device according to the invention are indenofluorenamine derivatives (for example in accordance with WO 06/122630 or WO 06/100896), the amine derivatives disclosed in EP 1661888, hexaazatriphenylene derivatives (for example in accordance with WO 01/049806), amine derivatives containing condensed aromatic rings (for example in accordance with U.S. Pat. No. 5,061,569), the amine derivatives disclosed in WO 95/09147, monobenzoindenofluorenamines (for example in accordance with WO 08/006449), dibenzolndenofluorenamines (for example in accordance with WO 07/140847), spirobifluorenamines (for example in accordance with WO 2012/034627 or WO 2013/120577), fluorenamines (for example in accordance with the as applications EP 2875092, EP 2875699 and EP 2875004), spirodibenzopyranamines (for example in accordance with WO 2013/083216) and dihydroacridine derivatives (for example in accordance with WO 2012/150001). The compounds according to the invention can also be used as hole-transport materials.
The cathode of the organic electroluminescent device preferably comprises metals having a low work function, metal alloys or multilayered structures comprising various metals, such as, for example, alkaline-earth metals, alkali metals, main-group metals or lanthanoids (for example Ca, Ba, Mg, Al, in, Mg, Yb, Sm, etc.). Also suitable are alloys comprising an alkali metal or alkaline-earth metal and silver, for example an alloy comprising magnesium and silver. In the case of multilayered structures, further metals which have a relatively high work function, such as, for example, Ag or Al, can also be used in addition to the said metals, in which case combinations of the metals, such as, for example, Ca/Ag, Mg/Ag or Ag/Ag, are generally used. It may also be preferred to introduce a thin interlayer of a material having a high dielectric constant between a metallic cathode and the organic semiconductor. Suitable for this purpose are, for example, alkali metal fluorides or alkaline-earth metal fluorides, but also the corresponding oxides or carbonates (for example LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.). Furthermore, lithium quinolinate (LiQ) can be used for this purpose. The layer thickness of this layer is preferably between 0.5 and 5 nm.
The anode preferably comprises materials having a high work function. The anode preferably has a work function of greater than 4.5 eV vs. vacuum. Suitable for this purpose are on the one hand metals having a high redox potential, such as, for example, Ag, Pt or Au. On the other hand, metal/metal oxide electrodes (for example Al/Ni/NiOx, Al/PtOx) may also be preferred. For some applications, at least one of the electrodes must be transparent or partially transparent in order to facilitate either irradiation of the organic material (organic solar cells) or the coupling-out of light (OLEDs, 0-lasers). Preferred anode materials here are conductive mixed metal oxides. Particular preference is given to indium tin oxide (ITO) or indium zinc oxide (IZO). Preference is furthermore given to conductive, doped organic materials, in particular conductive doped polymers.
The device is appropriately (depending on the application) structured, provided with contacts and finally sealed, since the lifetime of the devices according to the invention is shortened in the presence of water and/or air.
In a preferred embodiment, the organic electroluminescent device according to the invention is characterised in that one or more layers are coated by means of a sublimation process, in which the materials are applied by vapour deposition in vacuum sublimation units at an initial pressure of less than 10−5 mbar, preferably less than 10−6 mbar. However, it is also possible here for the initial pressure to be even lower, for example less than 10−7 mbar.
Preference is likewise given to an organic electroluminescent device, characterised in that one or more layers are coated by means of the OVPD (organic vapour phase deposition) process or with the aid of carrier-gas sublimation, in which the materials are applied at a pressure of between 10−5 mbar and 1 bar. A special case of this process is the OVJP (organic vapour jet printing) process, in which the materials are applied directly through a nozzle and are thus structured (for example M. S. Arnold et al., Appl. Phys. Lett. 2008, 92, 053301).
Preference is furthermore given to an organic electroluminescent device, characterised in that one or more layers are produced from solution, such as, for example, by spin coating, or by means of any desired printing process, such as, for example, screen printing, flexographic printing, nozzle printing or offset printing, but particularly preferably LITI (light induced thermal imaging, thermal transfer printing) or ink-jet printing. Soluble compounds of the formula (I) are necessary for this purpose. High solubility can be achieved through suitable substitution of the compounds.
Also possible are hybrid processes, in which, for example, one or more layers are applied from solution and one or more further layers are applied by vapour deposition. Thus, it is possible, for example, to apply the emitting layer from solution and to apply the electron-transport layer by vapour deposition.
These processes are generally known to the person skilled in the art and can be applied by him without inventive step to organic electroluminescent devices comprising the compounds according to the invention.
In accordance with the invention, the electronic devices comprising one or more compounds according to the invention can be employed in displays, as light sources in lighting applications and as light sources in medical and/or cosmetic applications (for example light therapy).
The invention will now be explained in greater detail by the following examples, without wishing to restrict it thereby.
a) Host H1
Synthesis of Compound A1:
7.9 g (32 mmol) 3,6-Dichloro-phenanthrene (20851-90-5), 30.4 g (80 mmol) 4,4,5,5-tetramethyl-2-(10-phenyl-9-anthracenyl)-1,3,2-dioxaborolane (460347-59-5), 29.5 g (128 mmol) potassium phosphate monohydrate are dissolved in 750 ml THF/water (2:1). 813 mg (0.96 mmol)) XPhos Palladacycle Gen. 3 are added and the mixture is stirred at 65° C. After 16 hours the reaction mixture is allowed to come to room temperature. The reaction mixture is filtered and washed with cold THF. The precipitate is purified by hot extraction over aluminum oxide (toluene) and further purified by crystallization out of toluene/ethanol and toluene/heptane up to a purity of >99.9 by HPLC. The remaining solvents are removed by tempering at 300° C. at 10−5 bar for 2 hours.
Yield: 4.9 g (7.2 mmol, 23%) of a pale yellow solid
Following compounds can be synthesized in analogous manner:
Synthesis of Compound 11:
9.3 g (32 mmol) 3-Bromo-6-chloro-phenanthrene (892550-44-6), 13.3 g (35 mmol) 4,4,5,5-tetramethyl-2-(10-phenyl-9-anthracenyl)-1,3,2-dioxaborolane (460347-59-5), 11.5 g (50 mmol) potassium phosphate monohydrate are dissolved in 750 ml THF/water (2:1). 813 mg (0.96 mmol)) XPhos Palladacycle Gen. 3 are added and the mixture is stirred at 65° C. After 16 hours the reaction mixture is allowed to come to room temperature. The mixture is diluted with 300 ml toluene. The aqueous phase is extracted with toluene (2×200 ml) and the combined organic phases are washed with water (2×200 ml) dried over magnesium sulfate, filtered and reduced under reduced pressure. The remaining solid is filtered over silica (toluene) and crystalized out of toluene/ethanol up to a purity of 98% by HPLC.
Yield 10.7 g (23 mmol, 72%)
Following compounds can be synthesized in analogous manner:
Synthesis of Compound B1:
9.3 g (20 mmol) 11, 16.0 g (30 mmol) 4,4,5,5-tetramethyl-2-(10-{5-phenyl[1,1′-biphenyl]-3-yl}anthracen-9-yl)-1,3,2-dioxaborolane (1016653-38-5), 11.5 g (50 mmol) potassium phosphate monohydrate are dissolved in 750 ml THF/water (2:1). 813 mg (0.96 mmol)) XPhos Palladacycle Gen. 3 are added and the mixture is stirred at 65° C. After 16 hours the reaction mixture is allowed to come to room temperature. The mixture is diluted with 300 ml toluene. The aqueous phase is extracted with toluene (2×200 ml) and the combined organic phases are washed with water (2×200 ml) dried over magnesium sulfate, filtered and reduced under reduced pressure. The remaining solid purified by hot extraction over aluminum oxide (toluene) and crystalized out of toluene/ethanol and toluene/heptane up to a purity of >99.9% by HPLC. The remaining solvents are removed by tempering at 300° C. and 10−5 bar for 2 hours.
Yield: 7.5 g (9 mmol, 45%)
Following compounds can be synthesized in analogous manner:
b) Host H2
The syntheses of the hosts of formula (H2) are known to the person skilled in the art and are described, for example, in WO 2008/145239 and WO 2015/158409. Further syntheses examples are described below:
Synthesis of C-1
In an autoclave C-I1 (1818872-84-2; 10 g, 19.5 mmol) is dissolved in a mixture of 700 ml toluene-d8 and D20 (5:2) and degassed and flushed with nitrogen, 20 g Pt—C 5% is added and the mixture is stirred at 165° C. After 11 days the mixture was cooled down to room temperature and the catalyst was filtered of and the two phases are separated. The organic phase is reduced under reduced pressure. The remaining solid is purified by filtration over silica (3 times, toluene as eluent) and several crystallizations out of dichloromethane:cyclohexane and toluene:n-heptane up to a HPLC purity of 99.9%. The remaining solid was dried by tempering at 250° C. at 10−5 bar. The deuterated product (D22-28) is obtained as colorless powder. The grade of deuteration is obtained by ASAP-MS, 1H-NMR, 13C-NMR and 2D-NMR. Yield: 5.4 g (10.5 mmol; 54%).
Synthesis of D1
10 g (19.7 mmol) 7-ethyl-4-(10-phenylanthracen-9-yl)tetraphene are dissolved in 230 mL toluene-D8. 10.4 ml (0.12 mol)Trifluoromethanesulfunic acid are added dropwise and the mixture is stirred at room temperature. After two hours 47 ml D20 are added and the mixture is stirred for 10 minutes until it was added to an aqueous potassium phosphate solution. The mixture is extracted with toluene and the combined organic phases are dried over sodium sulfate. The organic phase is reduced under reduced pressure. The remaining solid is purified by column chromatography and several crystallizations out of dichloromethane:cyclohexane and toluene:n-heptane up to a HPLC purity of 99.9%. Yield 5.7 g (10.8 mmol, 55%)
a) Preparation of Films and Devices
Glass substrates covered with pre-structured ITO (50 nm) and bank material are cleaned using ultrasonication in de-ionized water. In the following, the substrates are dried using an air-gun and subsequently annealed on a hotplate at 230° C. for 2 hours.
All following process steps are carried out in yellow light.
The following layer sequence is shown in
A hole-injection layer (HIL) is inkjet-printed onto the substrate with a thickness of 20 nm and dried in vacuum. For this the HIL ink has a solid concentration of 6 g/l. The HIL is then annealed at 200° C. for 30 minutes. Inkjet-printing and annealing of the HIL is carried out in air. As the HIL material, a holetransporting, cross-linkable polymer and a p-doped salt are dissolved in 3-phenoxy toluene. The materials are described i.e. in WO2016/107668, WO2013/081052 and EP2325190.
On top of the HIL, a hole-transport layer is inkjet-printed under ambient conditions, dried in vacuum and annealed at 210° C. for 30 minutes in argon atmosphere. The hole-transport layer is either the polymer of the structure shown in Table 1 (HTM1), which is synthesized in accordance with WO2013156130 or the polymer HTM2 (Table 1), which is synthesized in accordance with WO2018/114882.
The polymer is dissolved in 3-phenoxy toluene, so that the solution typically has a solid content of approx. 5 g/l if, as here, the layer thickness of 20 nm which is typical for a device, is to be achieved by means of inkjet printing. The layers are applied by inkjet printing in ambient atmosphere, dried in vacuum and annealed by heating at 210° C. for 30 min in argon atmosphere.
The emission layer comprises a matrix material (one host compound or two host compounds) and a dopant as described in Table 2 below. The mixture for the emission layer is dissolved in 3-phenoxy toluene. The solid content of such solutions is about 10 mg/ml if, as here, the layer thickness of 30 nm which is typical for a device is to be achieved by means of inkjet-printing. The blue emissive layer (B-EML) is also inkjet-printed, then vacuum dried and annealed at 150° C. for 10 minutes. Inkjet-printing is done in ambient atmosphere, whereas the annealing is done in argon atmosphere.
The devices, that are prepared according to
For the preparation of devices according to
After evaporation, the devices are encapsulated in a glovebox in argon atmosphere.
b) Evaluation of Emissive Film Homogeneity
For the production of displays, it is very important to get a very good pixel homogeneity while having good device performance at the same time. Layer thickness inhomogeneities cause uneven luminance distributions with areas of thinner film thickness showing increased luminance and thicker areas with reduced luminance. Such inhomogeneities vary from pixel to pixel thereby prohibiting a reproduceable appearance among the pixels. In combination, this will lead to a negative perception of such a display's quality. Therefore, the present invention addresses the topic of EML film homogeneity and device performance. The first step for the evaluation is thereby the examination of the film homogeneity. For this the stack shown in
In order to assess the homogeneity of the printed films, their topography is characterized along an 8 μm profile by a profilometer and the Rp-v (peak-to-valley) value as well as the root mean square deviation of the roughness are calculated. A profile-meter Alpha-step D120 from KLA-Tencor Corporation with a 2 μm stylus is used to measure the film profiles. The Rp-v values correspond to the height differences of the measured maximum (Rp) and minimum peaks (Rv) within the measured profiles. For ease of visibility, the baseline of the film profiles is subtracted such that the minimum peak corresponds to a height of 0 nm and the axis scales are the same for all diagrams.
The following two Formulas are used to determine the film homogeneity: The peak-to-valley Rp-v, which indicates the maximum height difference within the layer (Formula 1) and the root-mean-squared roughness RMS, which uses the root-mean-squared values of the height differences to the mean line zi (Formula 2).
The example PE1, which comprise a host mixture according to the invention, shows a significantly reduced Rp-v and RMS compared to PR2 and corresponds to a much smoother film (
Furthermore, the example PE1 also shows a similar Rp-v and RMS compared to PR1, while leading to better OLED performance as shown below (see Table 5f, Reference 11 and Example 14).
Further film homogeneities of additional emitting layers (EMLs) are shown in Table 2-3 below and the performances of the OLEDs comprising the corresponding EMLs are shown in Tables 5a to 5k.
For the emitting layers having the profiles PE1, PE2, PE3, PE4, PE5, PE8, PE7, PE8, PE9, PE11 and PE12, the same discussion as for PE1 above is valid.
The performances of devices employing the mixed host EMLs having the profiles PE1 to PE12 can be compared to other devices (see Tables 5a to 5k).
c) Device Results
The devices like shown in
After the encapsulation in a glovebox, the OLEDs are characterized by standard methods. For this purpose, the electroluminescence spectra, current/voltage/luminance characteristic curves (IUL characteristic curves) assuming Lambert emission characteristics and the (operating) lifetimes are determined. The IUL characteristic curves are used to determine characteristic figures of merit such as external quantum efficiency (in %) at a certain luminance. The device is driven with constant voltages, at each step of an applied voltage ramp. The device lifetime is measured under a given current with an initial luminance. The luminance is then measured over time by a calibrated photodiode.
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All shown examples of a mixed host system show an improved device performance compared to single host type H1, whereas similar performances as with the hosts type H2 can be reached.
This is independent of the used emitter and the used emitter concentration.
As discussed above, the profiles are shown for References 11 and 12 and Example 14 and Example 15 from Table 5f (see
The same discussion is valid for devices according to the present invention represented in Tables 5a to 5k.
With the help of the content of the invention, it is possible to achieve a good OLED device performance while at the same time ensuring homogeneous film quality.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20163090.2 | Mar 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/056390 | 3/12/2021 | WO |
